Sample records for adsorption time initial

  1. Enhanced initial protein adsorption on engineered nanostructured cubic zirconia.

    PubMed

    Sabirianov, R F; Rubinstein, A; Namavar, F

    2011-04-14

    Motivated by experimentally-observed biocompatibility enhancement of nanoengineered cubic zirconia (ZrO(2)) coatings to mesenchymal stromal cells, we have carried out computational analysis of the initial immobilization of one known structural fragment of the adhesive protein (fibronectin) on the corresponding surface. We constructed an atomistic model of the ZrO(2) nano-hillock of 3-fold symmetry based on Atom Force Microscopy and Transmission Electron Microscopy images. First principle quantum mechanical calculations show a substantial variation of electrostatic potential at the hillock due to the presence of surface features such as edges and vertexes. Using an implemented Monte Carlo simulated annealing method, we found the orientation of the immobilized protein on the ZrO(2) surface and the contribution of the amino acid residues from the protein sequence to the adsorption energy. Accounting for the variation of the dielectric permittivity at the protein-implant interface, we used a model distance-dependent dielectric function to describe the inter-atom electrostatic interactions in the adsorption potential. We found that the initial immobilization of the rigid protein fragment on the nanostructured pyramidal ZrO(2) surface is achieved with a magnitude of adsorption energy larger than that of the protein on the smooth (atomically flat) surface. The strong attractive electrostatic interactions are a major contributing factor in the enhanced adsorption at the nanostructured surface. In the case of adsorption on the flat, uncharged surface this factor is negligible. We show that the best electrostatic and steric fit of the protein to the inorganic surface corresponds to a minimum of the adsorption energy determined by the non-covalent interactions.

  2. Periodic protein adsorption at the gold/biotin aqueous solution interface: evidence of kinetics with time delay

    NASA Astrophysics Data System (ADS)

    Neff, H.; Laborde, H. M.; Lima, A. M. N.

    2016-11-01

    An oscillatory molecular adsorption pattern of the protein neutravidin from aqueous solution onto gold, in presence of a pre-deposited self assembled mono-molecular biotin film, is reported. Real time surface Plasmon resonance sensing was utilized for evaluation of the adsorption kinetics. Two different fractions were identified: in the initial phase, protein molecules attach irreversibly onto the Biotin ligands beneath towards the jamming limit, forming a neutravidin-biotin fraction. Afterwards, the growth rate exhibits distinct, albeit damped adsorption-desorption oscillations over an extended time span, assigned to a quasi reversibly bound fraction. These findings agree with, and firstly confirm a previously published model, proposing macro-molecular adsorption with time delay. The non-linear dynamic model is applicable to and also resembles non-damped oscillatory binding features of the hetero-catalytic oxidation of carbon monoxide molecules on platinum in the gas phase. An associated surface residence time can be linked to the dynamics and time scale required for self-organization.

  3. The effect of tubing dwell time on insulin adsorption during intravenous insulin infusions.

    PubMed

    Thompson, Cecilia D; Vital-Carona, Jessica; Faustino, E Vincent S

    2012-10-01

    Insulin adsorbs to plastic tubing, which decreases the concentration of an insulin solution delivered from an intravenous infusion set. Dwelling insulin within tubing before starting the infusion decreases adsorption but delays treatment initiation and wastes time in infusion preparation. The lack of data on dwell time effects results in wide variability in practice. We aim to determine the effect of dwell time on insulin concentration from intravenous infusion tubing. In this in vitro study, we used insulin solutions with concentrations of 0.1 unit/mL, 1 unit/mL, and 10 units/mL. Each solution dwelled in intravenous infusion sets for 0, 15, 30, or 60 min. After the dwell, we measured insulin concentrations from the solution bags and tubing. We repeated each insulin concentration-dwell time combination five times. Comparisons were performed using analyses of variance. For each of the three insulin concentrations, the mean insulin concentrations from the tubing were not significantly different between dwell times. Duration of dwell time did not affect insulin adsorption in polypropylene intravenous infusion sets. We recommend that following a 20-mL flush, insulin infusions can be started without any dwell time. Removal of dwell times may improve clinical practice by minimizing preparation time and will allow faster initiation of insulin infusion therapy.

  4. Time scale of random sequential adsorption.

    PubMed

    Erban, Radek; Chapman, S Jonathan

    2007-04-01

    A simple multiscale approach to the diffusion-driven adsorption from a solution to a solid surface is presented. The model combines two important features of the adsorption process: (i) The kinetics of the chemical reaction between adsorbing molecules and the surface and (ii) geometrical constraints on the surface made by molecules which are already adsorbed. The process (i) is modeled in a diffusion-driven context, i.e., the conditional probability of adsorbing a molecule provided that the molecule hits the surface is related to the macroscopic surface reaction rate. The geometrical constraint (ii) is modeled using random sequential adsorption (RSA), which is the sequential addition of molecules at random positions on a surface; one attempt to attach a molecule is made per one RSA simulation time step. By coupling RSA with the diffusion of molecules in the solution above the surface the RSA simulation time step is related to the real physical time. The method is illustrated on a model of chemisorption of reactive polymers to a virus surface.

  5. The Effect of Tubing Dwell Time on Insulin Adsorption During Intravenous Insulin Infusions

    PubMed Central

    Vital-Carona, Jessica; Faustino, E. Vincent S.

    2012-01-01

    Abstract Background Insulin adsorbs to plastic tubing, which decreases the concentration of an insulin solution delivered from an intravenous infusion set. Dwelling insulin within tubing before starting the infusion decreases adsorption but delays treatment initiation and wastes time in infusion preparation. The lack of data on dwell time effects results in wide variability in practice. We aim to determine the effect of dwell time on insulin concentration from intravenous infusion tubing. Materials and Methods In this in vitro study, we used insulin solutions with concentrations of 0.1 unit/mL, 1 unit/mL, and 10 units/mL. Each solution dwelled in intravenous infusion sets for 0, 15, 30, or 60 min. After the dwell, we measured insulin concentrations from the solution bags and tubing. We repeated each insulin concentration–dwell time combination five times. Comparisons were performed using analyses of variance. Results For each of the three insulin concentrations, the mean insulin concentrations from the tubing were not significantly different between dwell times. Duration of dwell time did not affect insulin adsorption in polypropylene intravenous infusion sets. Conclusions We recommend that following a 20-mL flush, insulin infusions can be started without any dwell time. Removal of dwell times may improve clinical practice by minimizing preparation time and will allow faster initiation of insulin infusion therapy. PMID:22746979

  6. Adsorption of arsenic from aqueous solution using magnetic graphene oxide

    NASA Astrophysics Data System (ADS)

    Sherlala, A. I. A.; Raman, A. A.; Bello, M. M.

    2017-06-01

    A binary of graphene oxide (GO) and iron oxide (IO) was prepared and used for the removal of arsenic from aqueous solution. The synthesized compound was characterized using XRD analysis. The prepared composite was used for the adsorption of arsenic from aqueous solution. Central Composite Design was used to design the adsorption experiments and to investigate the effects of operational parameters (initial concentration of arsenic, adsorbent dosage, pH and time) on the adsorption capacity and efficiency. The adsorbent shows a high adsorption capacity for the arsenic. The adsorption efficiency ranges between 33.2 % and 99.95 %. The most significant factors affecting the adsorption capacity were found to be the initial concentration of arsenic and the adsorbent dosage. The initial pH of the solution slightly affects the adsorption capacity, with the maximum adsorption capacity occurring around pH 6 - 7. Thus, the developed adsorbent has a potential for effective removal of arsenic from aqueous solution.

  7. Adsorption of Crystal Violet Dye Using Zeolite A Synthesized From Coal Fly Ash

    NASA Astrophysics Data System (ADS)

    Jumaeri; Kusumastuti, E.; Santosa, S. J.; Sutarno

    2017-02-01

    Adsorption of Crystal Violet (CV) dye using zeolite A synthesized from coal fly ash (ZA) has been done. Effect of pH, contact time, and the initial concentration of dye adsorption was studied in this adsorption. Model experimental of adsorption isotherms and adsorption kinetics were also studied. The adsorption is done in a batch reactor at room temperature. A total of 0.01 g of zeolite A was added to the Erlenmeyer flask 50 mL containing 20 mL of the dye solution of Crystal Violet in a variety of conditions of pH, contact time and initial concentration. Furthermore, Erlenmeyer flask and its contents were shaken using an orbital shaker at a speed of 200 rpm. After a specified period of adsorption, the solution was centrifuged for 2 minutes so that the solids separated from the solution. The concentration of the dye after adsorption determined using Genesis-20 Spectrophotometer. The results showed that the Zeolite A synthesized from coal fly ash could be used as an effective adsorbent for Crystal Violet dye. The optimum adsorption occurs at pH 6, and contact time 45 minutes. At the initial concentration of 2 to 6 mg/L, adsorption is reduced from 79 to 62.8%. Crystal Violet dye adsorption in zeolite A fulfilled kinetic model of pseudo-order 2 and model of Freundlich adsorption isotherm.

  8. Comparative evaluation of cyanide removal by adsorption, biodegradation, and simultaneous adsorption and biodegradation (SAB) process using Bacillus cereus and almond shell.

    PubMed

    Dwivedi, Naveen; Balomajumder, Chandrajit; Mondal, Prasenji

    2016-07-01

    The present study aimed to investigate the removal efficiency of cyanide from contaminated water by adsorption, biodegradation and simultaneous adsorption and biodegradation (SAB) process individually in a batch reactor. Adsorption was achieved by using almond shell granules and biodegradation was conducted with suspended cultures of Bacillus cereus, whereas SAB process was carried out using Bacillus cereus and almond shell in a batch reactor. The effect of agitation time, pH, and initial cyanide concentration on the % removal of cyanide has been discussed. Under experimental conditions, optimum removal was obtained at pH 7 with agitation time of 48 hrs and temperature of 35 degrees C. Cyanide was utilized by bacteria as sole source of nitrogen for growth. The removal efficiencies of cyanide by adsorption, biodegradation, and SAB were found to be 91.38%, 95.87%, and 99.63%, respectively, at initial cyanide concentration of 100 mg l(-1). The removal efficiency of SAB was found to be better as compared to that of biodegradation and adsorption alone.

  9. Nickel adsorption onto polyurethane ethylene and vinyl acetate sorbents.

    PubMed

    Iqbal, Munawar; Ali, Zahid; Qamar, M Afzal; Ali, Abid; Hussain, Fida; Abbas, Mazhar; Nisar, Jan

    2017-07-01

    The present study was conducted to appraise the efficiencies of polyurethane ethylene sorbent (PES) and vinyl acetate sorbent (VAS) for nickel (Ni) adsorption. Process variables, i.e. Ni(II) ions initial concentration, pH, contact time and adsorbent dosage were optimized by response surface methodology (RSM) approach. The Ni(II) adsorption was fitted to the kinetic models (pseudo-first-order and pseudo-second-order) and adsorption isotherms (Freundlich and Langmuir). At optimum conditions of process variables, 171.99 mg/g (64.7%) and 388.08 mg/g (92.7%) Ni(II) was adsorbed onto PES and VAS, respectively. The RSM analysis revealed that maximum Ni(II) adsorption can be achieved at 299 mg/L Ni(II) ions initial concentration, 4.5 pH, 934 min contact time and 1.3 g adsorbent dosage levels for PES, whereas the optimum values for VAS were found to be 402 mg/L Ni(II) ions initial concentration, 4.6 pH, 881 min contact time and 1.2 g adsorbent dosage, respectively. The -OH and -C = O- were involved in the Ni(II) adsorption onto PES and VAS adsorbents. At optimum levels, up to 53.67% and 80.0% Ni(II) was removed from chemical industry wastewater using PES and VAS, respectively, which suggest that PES and VAS could possibly be used for Ni(II) adsorption from industrial wastewater.

  10. Precursor state of oxygen molecules on the Si(001) surface during the initial room-temperature adsorption

    NASA Astrophysics Data System (ADS)

    Hwang, Eunkyung; Chang, Yun Hee; Kim, Yong-Sung; Koo, Ja-Yong; Kim, Hanchul

    2012-10-01

    The initial adsorption of oxygen molecules on Si(001) is investigated at room temperature. The scanning tunneling microscopy images reveal a unique bright O2-induced feature. The very initial sticking coefficient of O2 below 0.04 Langmuir is measured to be ˜0.16. Upon thermal annealing at 250-600 °C, the bright O2-induced feature is destroyed, and the Si(001) surface is covered with dark depressions that seem to be oxidized structures with -Si-O-Si- bonds. This suggests that the observed bright O2-induced feature is an intermediate precursor state that may be either a silanone species or a molecular adsorption structure.

  11. Study on Adsorption of Chromium (VI) by Activated Carbon from Cassava Sludge

    NASA Astrophysics Data System (ADS)

    Yang, Jinhui; Li, Chuanshu; Yang, Bin; Kang, Sijun; Zhang, Zhen

    2018-03-01

    In this paper, a new type of adsorbent prepared by waste sludge from alcohol production industry was used to adsorb Cr (VI) in activated carbon from cassava sludge. A series of static adsorption experiments were carried out on the initial concentration of solution Cr (VI), pH value of solution, adsorption time and dosage of adsorbent. The results of single factor experiments show that the removal rate of Cr (VI) increases with the initial concentration of Cr(VI), while the adsorption amount is opposite. When the pH value of the solution is low, the adsorption effect of activated carbon is better.The adsorption time should be controlled within 40-60min. When the activated carbon dosage is increased, the removal rate increases but the adsorption capacity decreases.

  12. Malachite Green Adsorption by Spent Coffee Grounds

    NASA Astrophysics Data System (ADS)

    Syamimie Atirah Mat, Siti; Zati Hanani Syed Zuber, Sharifah; Rahim, Siti Kartini Enche Ab; Sohaimi, Khairunissa Syairah Ahmad; Halim, Noor Amirah Abdul; Fauziah Zainudin, Nor; Aida Yusoff, Nor; Munirah Rohaizad, Nor; Hidayah Ishak, Noor; Anuar, Adilah; Sarip, Mohd Sharizan Md

    2018-03-01

    In this work, the ability of spent coffee grounds (SCG) as a low-cost adsorbent to remove malachite green (MG) from aqueous solutions was studied. Batch adsorption tests were carried out to observe the effect of various experimental parameters such as contact time, initial concentration of malachite green and adsorbent dosage on the removal of dye. The results obtained show that the percentage of dye removal will decreased with the increased of initial concentration of dye in the range of 50 mg/L to 250 mg/L. Besides, percentage removal of dye was also found to be increased as the contact time increased until it reached equilibrium condition. The results also showed that the adsorbent dosage in range of 0.2 g to 1.0 g is proportional to the percentage removal of malachite green dye. Study on the kinetic adsorption and isotherm adsorption has also been investigated. The adsorption isotherm data were described by Langmuir isotherm with high-correlation coefficients while the experimental data showed the pseudo-second-order kinetics model was the best model for the adsorption of MG by SCG with the coefficients of correlation R2 > 0.9978.

  13. Driving force behind adsorption-induced protein unfolding: a time-resolved X-ray reflectivity study on lysozyme adsorbed at an air/water interface.

    PubMed

    Yano, Yohko F; Uruga, Tomoya; Tanida, Hajime; Toyokawa, Hidenori; Terada, Yasuko; Takagaki, Masafumi; Yamada, Hironari

    2009-01-06

    Time-resolved X-ray reflectivity measurements for lysozyme (LSZ) adsorbed at an air/water interface were performed to study the mechanism of adsorption-induced protein unfolding. The time dependence of the density profile at the air/water interface revealed that the molecular conformation changed significantly during adsorption. Taking into account previous work using Fourier transform infrared (FTIR) spectroscopy, we propose that the LSZ molecules initially adsorbed on the air/water interface have a flat unfolded structure, forming antiparallel beta-sheets as a result of hydrophobic interactions with the gas phase. In contrast, as adsorption continues, a second layer forms in which the molecules have a very loose structure having random coils as a result of hydrophilic interactions with the hydrophilic groups that protrude from the first layer.

  14. Optical luminescence studies of diffusion times at the potassium ethyl xanthate adsorption layer on the surface of sphalerite minerals

    NASA Astrophysics Data System (ADS)

    Todoran, R.; Todoran, D.; Anitas, E. M.; Szakács, Zs

    2016-08-01

    We propose reflectance measurements as a method for the evaluation of the kinetics of adsorption processes, to compute the diffusion times of the adsorption products at the thin layers formed at the sphalerite natural mineral-potassium ethyl xanthate solution interface. The method is based on the intensity measurement of the reflected monochromatic radiation obtained from the mineral-xanthate thin layer as a function of time. These determinations were made at the thin layer formed between the sphalerite or activated sphalerite natural minerals with potassium ethyl xanthate, for different solutions concentrations and pH values at constant temperature. Diffusion times of desorbed molecular species into the liquid bring important information about the global kinetics of the ions in this phase during adsorption processes at interfaces. Analysing the time dependence of this parameter one concluded on the diffusion properties of the xanthate molecule in the solution depending on its concentration and pH, knowing that at the initial time these molecules had a uniform spread. This method enabled us to determine that, in time interval of approximately 35 minutes to achieve dynamic equilibrium in the formation of the interface layer, one had three different kinetic behaviours of our systems. In the first 5-8 min one had highly adsorbent character, the state of equilibrium is followed by low adsorbent properties. Gaining information on the adsorption kinetics in the case of xanthate on mineral surface leads to the optimization of the industrial froth flotation process.

  15. Adsorption of heavy metal ions by sawdust of deciduous trees.

    PubMed

    Bozić, D; Stanković, V; Gorgievski, M; Bogdanović, G; Kovacević, R

    2009-11-15

    The adsorption of heavy metal ions from synthetic solutions was performed using sawdust of beech, linden and poplar trees. The adsorption depends on the process time, pH of the solution, type of ions, initial concentration of metals and the sawdust concentration in suspension. The kinetics of adsorption was relatively fast, reaching equilibrium for less than 20 min. The adsorption equilibrium follows Langmuir adsorption model. The ion exchange mechanism was confirmed assuming that the alkali-earth metals from the adsorbent are substituted by heavy metal ions and protons. On lowering the initial pH, the adsorption capacity decreased, achieving a zero value at a pH close to unity. The maximum adsorption capacity (7-8 mg g(-1) of sawdust) was achieved at a pH between 3.5 and 5 for all the studied kinds of sawdust. The initial concentration of the adsorbate and the concentration of sawdust strongly affect the process. No influence of particles size was evidenced. A degree of adsorption higher than 80% can be achieved for Cu(2+) ions but it is very low for Fe(2+) ions, not exceeding 10%.

  16. Adsorption of sunset yellow FCF from aqueous solution by chitosan-modified diatomite.

    PubMed

    Zhang, Y Z; Li, J; Li, W J; Li, Y

    2015-01-01

    Sunset yellow (SY) FCF is a hazardous azo dye pollutant found in food processing effluent. This study investigates the use of diatomaceous earth with chitosan (DE@C) as a modified adsorbent for the removal of SY from wastewater. Fourier transform infrared spectroscopy results indicate the importance of functional groups during the adsorption of SY. The obtained N2 adsorption-desorption isotherm values accord well with IUPAC type II. Our calculations determined a surface area of 69.68 m2 g(-1) for DE@C and an average pore diameter of 4.85 nm. Using response surface methodology, optimized conditions of process variables for dye adsorption were achieved. For the adsorption of SY onto DE@C, this study establishes mathematical models for the optimization of pH, contact time and initial dye concentration. Contact time plays a greater role in the adsorption process than either pH or initial dye concentration. According to the adjusted correlation coefficient (adj-R2>0.97), the models used here are suitable for illustration of the adsorption process. Theoretical experimental conditions included a pH of 2.40, initial dye concentration of 113 mg L(-1) and 30.37 minutes of contact time. Experimental values for the adsorption rate (92.54%) were close to the values predicted by the models (95.29%).

  17. Improvement of pesticide adsorption capacity of cellulose fibre by high-energy irradiation-initiated grafting of glycidyl methacrylate

    NASA Astrophysics Data System (ADS)

    Takács, Erzsébet; Wojnárovits, László; Koczog Horváth, Éva; Fekete, Tamás; Borsa, Judit

    2012-09-01

    Cellulose as a renewable raw material was used for preparation of adsorbent of organic impurities in wastewater treatment. Hydrophobic surface of cellulose substrate was developed by grafting glycidyl methacrylate in simultaneous grafting using gamma irradiation initiation. Water uptake of cellulose significantly decreased while adsorption of phenol and a pesticide molecule (2,4-dichlorophenoxyacetic acid: 2,4-D) increased upon grafting. Adsorption equilibrium data fitted the Freundlich isotherm for both solutes.

  18. Off-Gas Adsorption Model Capabilities and Recommendations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lyon, Kevin L.; Welty, Amy K.; Law, Jack

    2016-03-01

    Off-gas treatment is required to reduce emissions from aqueous fuel reprocessing. Evaluating the products of innovative gas adsorption research requires increased computational simulation capability to more effectively transition from fundamental research to operational design. Early modeling efforts produced the Off-Gas SeParation and REcoverY (OSPREY) model that, while efficient in terms of computation time, was of limited value for complex systems. However, the computational and programming lessons learned in development of the initial model were used to develop Discontinuous Galerkin OSPREY (DGOSPREY), a more effective model. Initial comparisons between OSPREY and DGOSPREY show that, while OSPREY does reasonably well to capturemore » the initial breakthrough time, it displays far too much numerical dispersion to accurately capture the real shape of the breakthrough curves. DGOSPREY is a much better tool as it utilizes a more stable set of numerical methods. In addition, DGOSPREY has shown the capability to capture complex, multispecies adsorption behavior, while OSPREY currently only works for a single adsorbing species. This capability makes DGOSPREY ultimately a more practical tool for real world simulations involving many different gas species. While DGOSPREY has initially performed very well, there is still need for improvement. The current state of DGOSPREY does not include any micro-scale adsorption kinetics and therefore assumes instantaneous adsorption. This is a major source of error in predicting water vapor breakthrough because the kinetics of that adsorption mechanism is particularly slow. However, this deficiency can be remedied by building kinetic kernels into DGOSPREY. Another source of error in DGOSPREY stems from data gaps in single species, such as Kr and Xe, isotherms. Since isotherm data for each gas is currently available at a single temperature, the model is unable to predict adsorption at temperatures outside of the set of data

  19. Rapid Adsorption of Copper(II) and Lead(II) by Rice Straw/Fe3O4 Nanocomposite: Optimization, Equilibrium Isotherms, and Adsorption Kinetics Study

    PubMed Central

    Khandanlou, Roshanak; Ahmad, Mansor B.; Fard Masoumi, Hamid Reza; Shameli, Kamyar; Basri, Mahiran; Kalantari, Katayoon

    2015-01-01

    Rice straw/magnetic nanocomposites (RS/Fe3O4-NCs) were prepared via co-precipitation method for removal of Pb(II) and Cu(II) from aqueous solutions. Response surface methodology (RSM) was utilized to find the optimum conditions for removal of ions. The effects of three independent variables including initial ion concentration, removal time, and adsorbent dosage were investigated on the maximum adsorption of Pb (II) and Cu (II). The optimum conditions for the adsorption of Pb(II) and Cu(II) were obtained (100 and 60 mg/L) of initial ion concentration, (41.96 and 59.35 s) of removal time and 0.13 g of adsorbent for both ions, respectively. The maximum removal efficiencies of Pb(II) and Cu(II) were obtained 96.25% and 75.54%, respectively. In the equilibrium isotherm study, the adsorption data fitted well with the Langmuir isotherm model. The adsorption kinetics was best depicted by the pseudo-second order model. Desorption experiments showed adsorbent can be reused successfully for three adsorption-desorption cycles. PMID:25815470

  20. Surface Complexation Modeling of Fluoride Adsorption by Soil and the Role of Dissolved Aluminum on Adsorption

    NASA Astrophysics Data System (ADS)

    Padhi, S.; Tokunaga, T.

    2017-12-01

    Adsorption of fluoride (F) on soil can control the mobility of F and subsequent contamination of groundwater. Hence, accurate evaluation of adsorption equilibrium is a prerequisite for understanding transport and fate of F in the subsurface. While there have been studies for the adsorption behavior of F with respect to single mineral constituents based on surface complexation models (SCM), F adsorption to natural soil in the presence of complexing agents needs much investigation. We evaluated the adsorption processes of F on a natural granitic soil from Tsukuba, Japan, as a function of initial F concentration, ionic strength, and initial pH. A SCM was developed to model F adsorption behavior. Four possible surface complexation reactions were postulated with and without including dissolved aluminum (Al) and Al-F complex sorption. Decrease in F adsorption with the increase in initial pH was observed in between the initial pH range of 4 to 9, and a decrease in the rate of the reduction of adsorbed F with respect to the increase in the initial pH was observed in the initial pH range of 5 to 7. Ionic strength variation in the range of 0 to 100mM had insignificant effect on F removal. Changes in solution pH were observed by comparing the solution before and after F adsorption experiments. At acidic pH, the solution pH increased, whereas at alkaline pH, the solution pH decreased after equilibrium. The SCM including dissolved Al and the adsorption of Al-F complex can simulate the experimental results quite successfully. Also, including dissolved Al and the adsorption of Al-F complex to the model explained the change in solution pH after F adsorption.

  1. Degree of time dependency of kinetic coefficient as a function of adsorbate concentration; new insights from adsorption of tetracycline onto monodispersed starch-stabilized magnetic nanocomposite.

    PubMed

    Okoli, Chukwunonso P; Ofomaja, Augustine E

    2018-07-15

    The realization that the observed kinetic coefficient (k obs ) varies with time in most real-time adsorption system, as against the constant value conceived in the most widely-applied adsorption kinetic models, have attracted much attention in recent time. Understanding the factors that control the extent/degree of time dependency (otherwise known as fractal-like kinetics), is therefore central in taking manipulative advantage of this phenomenon in critical adsorption applications. This study therefore deployed non-fractal-like and fractal-like kinetic approach to study the adsorption of tetracycline on monodispersed starch-stabilized magnetite nanocomposite (MSM). MSM was synthesized by in-situ coprecipitation of magnetite in the presence of starch, and successfully characterized with classical solid-state techniques. Isotherm studies indicated that MSM has heterogenous surface adsorption sites. Equilibrium and kinetic data indicated the existence of π-cation interaction as the underlying mechanism, while pH study revealed that tetracycline was adsorbed in its zwitterion form. Though the non-fractal kinetic models exhibited some level of relevance in explaining the tetracycline adsorption interactions, the best fitting of the fractal-like pseudo second order model to the adsorption kinetic data, indicated that the real-time adsorption kinetics occurred in fractal-like manner. The study also revealed that the degree of time dependency of k obs had negative correlation with the initial tetracycline concentration. Apart from developing a low-cost strategy for addressing tetracycline water pollution, the result of this study serves a positive step towards gaining manipulative control of adsorption mechanism in potential application of MSM for targeted drug delivery and controlled release of tetracycline antibiotics. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Arsenic Adsorption Equilibrium Concentration and Adsorption Rate of Activated Carbon Coated with Ferric-Aluminum Hydroxides

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Sugita, H.; Oguma, T.; Hara, J.; Takahashi, S.

    2015-12-01

    In some areas of developing countries, ground or well water contaminated with arsenic has been reluctantly used as drinking water. It is highly desirable that effective and inexpensive arsenic removal agents should be developed and provided to reduce the potential health risk. Previous studies demonstrated that activated carbon coated with ferric-aluminum hydroxides (Fe-Al-C) has high adsorptive potential for removal of arsenic. In this study, a series of experiments using Fe-Al-C were carried to discuss adsorption equilibrium time, adsorption equilibrium concentration and adsorption rate of arsenic for Fe-Al-C. Fe-Al-C used in this study was provided by Astec Co., Ltd. Powder reagent of disodium hydrogen arsenate heptahydrate was dissolved into ion-exchanged water. The solution was then further diluted with ion-exchanged water to be 1 and 10 mg/L as arsenic concentration. The pH of the solution was adjusted to be around 7 by adding HCl and/or NaOH. The solution was used as artificial arsenic contaminated water in two types of experiments (arsenic adsorption equilibrium and arsenic adsorption rate tests). The results of the arsenic equilibrium tests were showed that a time period of about 3 days to reach apparent adsorption equilibrium for arsenic. The apparent adsorption equilibrium concentration and adsorbed amount of arsenic on Fe-Al-C adsorbent could be estimated by application of various adsorption isotherms, but the distribution coefficient of arsenic between solid and liquid varies with experimental conditions such as initial concentration of arsenic and addition concentration of adsorbent. An adsorption rate equation that takes into account the reduction in the number of effective adsorption sites on the adsorbent caused by the arsenic adsorption reaction was derived based on the data obtained from the arsenic adsorption rate tests.

  3. Adsorption of octylamine on titanium dioxide

    NASA Astrophysics Data System (ADS)

    Siwińska, Daria; Kołodziejczak-Radzimska, Agnieszka; Krysztafkiewicz, Andrzej; Jesionowski, Teofil

    2009-05-01

    Processes of adsorption and desorption of a model active substance (octylamine) on the surface of unmodified titanium dioxide (E 171) have been performed. The effects of concentration of octylamine and time of the process on the character of adsorption have been studied and the efficiency of the adsorption/desorption has been determined. The samples obtained have been studied by X-ray diffraction. The nitrogen adsorption/desorption isotherms, particle size distribution and absorption capacities of water, dibutyl phthalate and paraffin oil have been determined. The efficiency of octylamine adsorption on the surface of the titanium dioxide has been found positively correlated with the concentration of octylamine in the initial solution. The desorption of octylamine has decreased with increasing concentration of this compound adsorbed. For octylamine in low concentrations the physical adsorption has been found to dominate, which is desirable when using TiO 2 in the production of pharmaceuticals.

  4. [Adsorption characteristics of acetone and butanone onto honeycomb ZSM-5 molecular sieve].

    PubMed

    Du, Juan; Luan, Zhi-Qiang; Xie, Qiang; Ye, Ping-Wei; Li, Kai; Wang, Xi-Qin

    2013-12-01

    Adsorption capacity of acetone and acetone-butanone mixture onto honeycomb ZSM-5 molecular sieve was measured in this paper, and the influences of relative humidity, initial adsorbate concentration and airflow velocity on the adsorption process were investigated. Besides, adsorption performance parameters were calculated by Wheeler's equation. The results showed that relative humidity had no obvious influence on the acetone adsorption performance, which suggests that this material has good hydrophobic ability; in the low concentration range, the dynamic saturated adsorption capacity of acetone increased with the increase of initial concentration, but in the occasion of high concentration of acetone gas (more than 9 mg x L(-1)), the dynamic saturated adsorption capacity maintained at a certain level and did not vary with the increase of initial concentration; the increase of air flow velocity resulted in significant increase of acetone adsorption rate constant, at the same time the critical layer thickness of the adsorbent bed also increased significantly. In the cases of acetone-butanone mixture, the adsorption capacity of butanone onto ZSM-5 was clearly higher than that of acetone.

  5. Microcolumn studies of dye adsorption onto manganese oxides modified diatomite.

    PubMed

    Al-Ghouti, M A; Khraisheh, M A M; Ahmad, M N; Allen, S J

    2007-07-19

    The method described here cannot fully replace the analysis of large columns by small test columns (microcolumns). The procedure, however, is suitable for speeding up the determination of adsorption parameters of dye onto the adsorbent and for speeding up the initial screening of a large adsorbent collection that can be tedious if a several adsorbents and adsorption conditions must be tested. The performance of methylene blue (MB), a basic dye, Cibacron reactive black (RB) and Cibacron reactive yellow (RY) was predicted in this way and the influence of initial dye concentration and other adsorption conditions on the adsorption behaviour were demonstrated. On the basis of the experimental results, it can be concluded that the adsorption of RY onto manganese oxides modified diatomite (MOMD) exhibited a characteristic "S" shape and can be simulated effectively by the Thomas model. It is shown that the adsorption capacity increased as the initial dye concentration increased. The increase in the dye uptake capacity with the increase of the adsorbent mass in the column was due to the increase in the surface area of adsorbent, which provided more binding sites for the adsorption. It is shown that the use of high flow rates reduced the time that RY in the solution is in contact with the MOMD, thus allowing less time for adsorption to occur, leading to an early breakthrough of RY. A rapid decrease in the column adsorption capacity with an increase in particle size with an average 56% reduction in capacity resulting from an increase in the particle size from 106-250 microm to 250-500 microm. The experimental data correlated well with calculated data using the Thomas equation and the bed depth-service time (BDST) equation. Therefore, it might be concluded that the Thomas equation and the BDST equations can produce accurate predication for variation of dye concentration, mass of the adsorbent, flow rate and particle size. In general, the values of adsorption isotherm capacity

  6. Adsorption of ferrous ions onto montmorillonites

    NASA Astrophysics Data System (ADS)

    Qin, Dawei; Niu, Xia; Qiao, Min; Liu, Gang; Li, Hongxin; Meng, Zhenxiao

    2015-04-01

    The adsorption of Fe (II) onto montmorillonites was investigated through initial concentration, contact time, pH and temperature. During the whole adsorption process, the ascorbic acid (Vitamin C) was added as a kind of antioxidant, at the same time, deionized water (after boiling) and nitrogen protection were also used to avoid oxidation. The Fe2+/Fetotal ratio of the iron exists in the Fe-montmorillonites was found more than 95%. Two kinetic models, including pseudo-first-order and pseudo-second-order model, were used to analyze the adsorption process of Fe (II) on montmorillonites. The results of our study showed that adsorption process fitted with pseudo-second-order well. Adsorption isotherms showed that Langmuir model was better than Freundlich model. The thermodynamic parameters ΔG0 and ΔH0 were 3.696 kJ/mol and 6.689 kJ/mol (we just gave the values at 298 K), respectively. The positive values at different temperatures showed that the adsorption process was non-spontaneous and endothermic. The characteristics of materials were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Surface area and porosity analyzer, Thermogravimetric analysis (TGA), Differential scanning calorimeter (DSC) and Zeta potential distribution.

  7. Time and temperature dependent adsorption-desorption behaviour of pretilachlor in soil.

    PubMed

    Kaur, Paawan; Kaur, Pervinder

    2018-06-04

    Understanding and quantifying the adsorption-desorption behaviour of herbicide in soil is imperative for predicting their fate and transport in the environment. In the present study, the effect of time and temperature on the adsorption-desorption behaviour of pretilachlor in soils was investigated using batch equilibration technique. The adsorption-desorption kinetics of pretilachlor in soils was two step process and was well described by pseudo-second-order kinetic model. Freundlich model accurately predicted the sorption behaviour of pretilachlor. The adsorption-desorption of pretilachlor varied significantly with the concentration, temperature and properties of soil viz. organic matter and clay content. All the studied soils had non-linear slopes (n < 1) and degree of nonlinearity increased with increase in clay, organic matter content and temperature (p < 0.05). Desorption of pretilachlor was hysteretic in studied soils and hysteresis coefficient varied from 0.023 to 0.275. Thermodynamic analysis showed that pretilachlor adsorption onto soils was a feasible, spontaneous and endothermic process which becomes more favourable at high temperature. It could be inferred that the adsorption of pretilachlor on soils was physical in nature. Copyright © 2018 Elsevier Inc. All rights reserved.

  8. The effect of anatase TiO2 surface structure on the behavior of ethanol adsorption and its initial dissociation step: A DFT study

    NASA Astrophysics Data System (ADS)

    Zhang, Riguang; Liu, Zhixue; Ling, Lixia; Wang, Baojun

    2015-10-01

    The perfect and defective surfaces of anatase TiO2 including (1 0 1) and (0 0 1) surfaces have been chosen to probe into the effect of anatase TiO2 surface structure on the behavior of ethanol adsorption and initial dissociation step. Here, the results are obtained by density functional theory (DFT) calculation together with the periodic slab model. Our results show that the surface structure of anatase TiO2 can obviously affect the behavior of ethanol adsorption and the catalytic activity of its initial dissociation step; firstly, on the perfect and defective surfaces of anatase (1 0 1), ethanol dominantly exists in the form of molecule adsorption; however, ethanol is the dissociative adsorption on the hydroxylated anatase (0 0 1), and the coexistences of molecular and dissociation adsorption modes on the perfect anatase (0 0 1). On the other hand, the initial dissociation step of ethanol with molecule adsorption prefers to begin with its O-H bond cleavage leading to CH3CH2O and H species rather than the cleavage of its α-C-H, β-C-H, C-C and C-O bonds, namely, the preferable O-H bond cleavage for the initial dissociation step of ethanol is independent of the surface structure of anatase TiO2; however, the corresponding catalytic activity of ethanol initial dissociation step with the O-H bond cleavage on different anatase TiO2 surfaces is in the following order: hydroxylated (0 0 1) > perfect (0 0 1) > defective (1 0 1) > perfect (1 0 1), suggesting that the catalytic activity for the initial dissociation step of ethanol is sensitive to the surface structure of anatase TiO2, and the hydroxylated (0 0 1) is the most favorable surface. Among these surfaces, the most favorable product for the initial dissociation step of ethanol is CH3CH2O species.

  9. Adsorption of Cd(II) Metal Ion on Adsorbent beads from Biomass Saccharomycess cereviceae - Chitosan

    NASA Astrophysics Data System (ADS)

    Hasri; Mudasir

    2018-01-01

    The adsorbent beads that was preparation from Saccharomycess cereviceae culture strain FN CC 3012 and shrimp shells waste and its application for adsorption of Cd (II) metal ion has been studied. The study start with combination of Saccharomycess cereviceae biomass to chitosan (Sc-Chi), contact time, pH of solution and initial concentration of cations. Total Cd(II) metal ion adsorbed was calculated from the difference of metal ion concentration before and after adsorption by AAS. The results showed that optimum condition for adsorption of Cd(II) ions by Sc-Chi beads was achieved with solution pH of 4, contact time of 60 minutes and initial concentration adsorption 100mg/L. The hydroxyl (-OH) and amino (-NH2) functional groups were believed to be responsible for the adsorption of Cd(II) ions.

  10. Response surface modeling of boron adsorption from aqueous solution by vermiculite using different adsorption agents: Box-Behnken experimental design.

    PubMed

    Demirçivi, Pelin; Saygılı, Gülhayat Nasün

    2017-07-01

    In this study, a different method was applied for boron removal by using vermiculite as the adsorbent. Vermiculite, which was used in the experiments, was not modified with adsorption agents before boron adsorption using a separate process. Hexadecyltrimethylammonium bromide (HDTMA) and Gallic acid (GA) were used as adsorption agents for vermiculite by maintaining the solid/liquid ratio at 12.5 g/L. HDTMA/GA concentration, contact time, pH, initial boron concentration, inert electrolyte and temperature effects on boron adsorption were analyzed. A three-factor, three-level Box-Behnken design model combined with response surface method (RSM) was employed to examine and optimize process variables for boron adsorption from aqueous solution by vermiculite using HDTMA and GA. Solution pH (2-12), temperature (25-60 °C) and initial boron concentration (50-8,000 mg/L) were chosen as independent variables and coded x 1 , x 2 and x 3 at three levels (-1, 0 and 1). Analysis of variance was used to test the significance of variables and their interactions with 95% confidence limit (α = 0.05). According to the regression coefficients, a second-order empirical equation was evaluated between the adsorption capacity (q i ) and the coded variables tested (x i ). Optimum values of the variables were also evaluated for maximum boron adsorption by vermiculite-HDTMA (HDTMA-Verm) and vermiculite-GA (GA-Verm).

  11. Improving lead adsorption through chemical modification of wheat straw by lactic acid

    NASA Astrophysics Data System (ADS)

    Mu, Ruimin; Wang, Minxiang; Bu, Qingwei; Liu, Dong; Zhao, Yanli

    2018-01-01

    This work describes the creation of a new cellulosic material derived from wheat straw modified by lactic acid for adsorption of lead in aqueous solution, called 0.3LANS (the concentration of the lactic acid were 0.3mol/L). Batch experiments were conducted to study the effects of initial pH value, contact time, adsorbent dose, initial concentration and temperature. Fourier transform infrared (FTIR), Elemental analysis, BET surface area and Scanning electron micrographs (SEM) analysis were used to investigate the chemical modification. Adsorption isotherm models namely, Langmuir, Freundlich were used to analyse the equilibrium data, and the Langmuir isotherm model provided the best correlation, means that the adsorption was chemical monolayer adsorption and the adsorption capacity qm was increased with increasing temperature, and reached 51.49mg/g for 0.3LANS at 35°C, showing adsorption was exothermic.

  12. Adsorption of malachite green dye from aqueous solution on the bamboo leaf ash

    NASA Astrophysics Data System (ADS)

    Kuntari, Priwidyanjati, Dessyntha Anggiani

    2017-12-01

    Bamboo leaf ash has been developed as an adsorbent material for removal malachite green from aqueous solution. Adsorption parameters have studied are contact time and initial pH. The effect of contact time and pH were examined in the batch adsorption processes. The physicochemical characters of bamboo leaf ash were investigated by using X-Ray Diffraction (XRD) and FT-IR spectroscopy. Malachite green concentration was determined by UV-Vis spectrophotometer. FT-IR spectrogram of bamboo leaf ash shows that typical fingerprint of adsorbent material with Si-O-Si or Al-O-Al group. The X-ray diffractograms of bamboo leaf ash show that adsorbent material has a highly amorphous nature. The percentage of adsorption was showed raised with increasing contact time. The optimum removal of malachite green when the initial dye concentration, initial pH, weight of adsorbent and contact time was 20 mg/L, 7, 0.25 g and 75 minutes respectively.

  13. Adsorptive removal of Auramine-O: kinetic and equilibrium study.

    PubMed

    Mall, Indra Deo; Srivastava, Vimal Chandra; Agarwal, Nitin Kumar

    2007-05-08

    Present study deals with the adsorption of Auramine-O (AO) dye by bagasse fly ash (BFA) and activated carbon-commercial grade (ACC) and laboratory grade (ACL). BFA is a solid waste obtained from the particulate collection equipment attached to the flue gas line of the bagasse fired boilers of cane sugar mills. Batch studies were performed to evaluate the influences of various experimental parameters like initial pH (pH(0)), contact time, adsorbent dose and initial concentration (C(0)) for the removal of AO. Optimum conditions for AO removal were found to be pH(0) approximately 7.0 and equilibrium time approximately 30 min for BFA and approximately 120 min for activated carbons. Optimum BFA, ACC and ACL dosages were found to be 1, 20 and 2g/l, respectively. Adsorption of AO followed pseudo-second order kinetics with the initial sorption rate for adsorption on BFA being the highest followed by those on ACL and ACC. The sorption process was found to be controlled by both film and pore diffusion with film diffusion at the earlier stages followed by pore diffusion at the later stages. Equilibrium isotherms for the adsorption of AO on BFA, ACC and ACL were analyzed by Freundlich, Langmuir, Dubinin-Radushkevich, and Temkin isotherm equations using linear correlation coefficient. Langmuir isotherm gave the best correlation of adsorption for all the adsorbents studied. Thermodynamic study showed that adsorption of AO on ACC (with a more negative Gibbs free energy value) is more favoured. BFA which was used without any pretreatment showed high surface area, pore volume and pore size exhibiting its potential to be used as an adsorbent for the removal of AO.

  14. Effect of hydrophobicity of pharmaceuticals and personal care products for adsorption on activated carbon: Adsorption isotherms, kinetics and mechanism.

    PubMed

    Kaur, Harkirat; Bansiwal, Amit; Hippargi, Girivyankatesh; Pophali, Girish R

    2017-09-11

    Adsorption of three pharmaceuticals and personal care products (PPCPs), namely caffeine, ibuprofen and triclosan on commercial powdered activated carbon was examined in aqueous medium. The contaminants were chosen based on their diverse log K ow (octanol-water partition coefficient) viz. - 0.07 for caffeine, 3.97 for ibuprofen and 4.76 for triclosan to examine the role of hydrophobicity on adsorption process. The adsorbent characterisation was achieved using BET surface area, SEM, pore size distribution studies and FTIR. Influence of mass of PAC, contact time, solution pH and initial concentration on adsorption capacity of PAC was studied. Adsorption isotherms and kinetics were applied to establish the mechanism of adsorption. The kinetics followed pseudo-second order with physisorption occurring through particle diffusion. The Freundlich model fitted best among the isotherm models. The adsorption capacity increased in the order CFN < IBU < TCS which correlates with increasing hydrophobicity (log K ow ), molecular weight and decreasing water solubility, respectively. We conclude that micro-pollutant hydrophobicity contributes towards adsorption on activated carbon.

  15. Role of organic matter on boron adsorption-desorption hysteresis of soils

    USDA-ARS?s Scientific Manuscript database

    In this study we evaluated the boron (B) adsorption/desorption reaction in six soils and examined the extent to which organic matter content, as well as incubation time affected B release. Six soils varying in initial pH, clay content, and were selected for the study. Adsorption experiments were c...

  16. Simultaneous adsorption of Cd²⁺ and BPA on amphoteric surfactant activated montmorillonite.

    PubMed

    Liu, Chongmin; Wu, Pingxiao; Zhu, Yajie; Tran, Lytuong

    2016-02-01

    The study mainly investigated the simultaneous adsorption of bisphenol A (BPA) and Cd(2+) from aqueous solution on octadecane-betaine modified montmorillonite (BS-Mt). The characteristics of the obtained materials were analyzed by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), Specific surface area (BET) and Scanning electron microscopy/Energy disperse spectroscopy (SEM/EDS), confirming that BS-18 was successfully introduced into Mt. Also, factors including initial solution pH, initial Cd(2+)/BPA concentration, contact time and adsorbent dosage on the adsorption processes were shown to be crucial for Cd(2+) adsorption, whereas had negligible effects on BPA adsorption. In this study, we found that pseudo-second-order model fitted well with the adsorption kinetic studies for both Cd(2+) and BPA with an equilibrium time of 24 h. The Cd(2+) and BPA adsorption isotherm could be well described by Freundlich model and Langmuir model, respectively. On the basis of kinetic models, the maximum adsorption capacity of Cd(2+) in aqueous solution was slightly enhanced after modification, indicating that Cd(2+) adsorption on BS-Mt was mainly attributed to direct electrostatic attraction and the chelate reaction, while the dramatic enhancement of maximum adsorption capacity for BPA was due to the hydrophobic interaction. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Fixed-bed adsorption study of methylene blue onto pyrolytic tire char

    NASA Astrophysics Data System (ADS)

    Makrigianni, Vassiliki; Giannakas, Aris; Papadaki, Maria; Albanis, Triantafyllos; Konstantinou, Ioannis

    2016-04-01

    In this work, the adsorption efficiency of acid treated pyrolytic tire char to cationic methylene blue (MB) dye adsorption from aqueous solutions was investigated by fixed-bed adsorption column experiments. The effects of the initial dye concentration (10 - 40 mg L-1) and feed flow rate (50 - 150 mL min -1) with a fixed bed height (15 cm) were studied in order to determine the breakthrough characteristics of the adsorption system. The Adams-Bohart, Yoon-Nelson and Thomas model were applied to the adsorption of MB onto char at different operational conditions to predict the breakthrough curves and to determine the characteristic parameters of the column. The results showed that the maximum adsorbed quantities decreased with increasing flow rate and increased with increasing initial MB concentration. Breakthrough time and exhaustion time increased with decreasing inlet dye concentration and flow rate. In contrast with Adams-Bohart model, Yoon-Nelson model followed by Thomas model were found more suitable to describe the fixed-bed adsorption of methylene blue by char. The correlation coefficient values R2 for both models at different operating conditions are higher than 0.9 and the low average relative error values provided very good fittings of experimental data at different operating conditions. Higher adsorption capacity of 3.85 mg g -1 was obtained at 15 cm of adsorbent bed height, flow rate of 100 mL min -1and initial MB concentration of 40 mg L-1. Although that activated carbons exhibited higher adsorption capacities in the literature, acid-treated pyrolytic tire char was found to be considerably efficient adsorbent for the removal of MB dye column taking into account the advantages of the simpler production process compared to activated carbons, as well as, the availability of waste tire feedstock and concurrent waste tire management.

  18. Adsorption of dimethyl trisulfide from aqueous solution on a low-cost adsorbent: thermally activated pinecone

    NASA Astrophysics Data System (ADS)

    Shang, Jingge; He, Wei; Fan, Chengxin

    2015-01-01

    Thermally activated pinecone (TAP) was used for the adsorption of dimethyl trisulfide (DMTS) from aqueous solutions, which was proved to be the main odorous in algae-caused black bloom. The effects of adsorbent dosage, adsorbate concentration and contact time on DMTS biosorption were studied. The TAP produced at 600°C exhibited a relatively high surface area (519.69 m2/g) and excellent adsorption capacity. The results show that the adsorption of DMTS was initially fast and that the equilibrium time was 6 h. Higher initial DMTS concentrations led to lower removal percentages but higher adsorption capacity. The removal percentage of DMTS increased and the adsorption capacity of TAP decreased with an increase in adsorbent dosage. The adsorption process conforms well to a pseudo-second-order kinetics model. The adsorption of DMTS is more appropriately described by the Freundlich isotherm ( R 2 =0.996 1) than by the Langmuir isotherm ( R 2 =0.916 9). The results demonstrate that TAP could be an attractive low-cost adsorbent for removing DMTS from water.

  19. Isotherm and thermodynamic studies of Zn (II) adsorption on lignite and coconut shell-based activated carbon fiber.

    PubMed

    Shrestha, Sohan; Son, Guntae; Lee, Seung Hwan; Lee, Tae Gwan

    2013-08-01

    The Zn (II) adsorption capacity of lignite and coconut shell-based activated carbon fiber (ACF) was evaluated as a function of initial Zn (II) concentration, temperature and contact time in batch adsorption process in this study. Adsorption uptake increased with initial Zn (II) concentration and temperature. Optimal contact time for the adsorption of Zn (II) ions onto lignite and coconut shell-based ACF was found to be 50 min. Removal percentage decreased from 88.0% to 78.54% with the increment in initial Zn (II) concentration from 5 to 50 mg L(-1). Equilibrium data fit well with Langmuir-I isotherm indicating homogeneous monolayer coverage of Zn (II) ions on the adsorbent surface. Maximum monolayer adsorption capacity of Zn (II) ions on ACF was found to be 9.43 mg g(-1). Surface morphology and functionality of ACF prior to and after adsorption were characterized by electron microscopy and infrared spectroscopy. Various thermodynamic parameters such as standard Gibbs free energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°) were evaluated. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Adsorption laboratory experiment for undergraduate chemical engineering: Introducing kinetic, equilibrium and thermodynamic concepts

    NASA Astrophysics Data System (ADS)

    Muryanto, S.; Djatmiko Hadi, S.

    2016-11-01

    Adsorption laboratory experiment for undergraduate chemical engineering program is discussed. The experiment demonstrated adsorption of copper ions commonly found in wastewater using bio-sorbent, i.e. agricultural wastes. The adsorption was performed in a batch mode under various parameters: adsorption time (up to 120 min), initial pH (2 to 6), adsorbent dose (2.0 to 12.0 g L-1), adsorbent size (50 to 170 mesh), initial Cu2+ concentration (25 to 100 ppm) and temperatures (room temp to 40°C). The equilibrium and kinetic data of the experiments were calculated using the two commonly used isotherms: Langmuir and Lagergren pseudo-first-order kinetics. The maximum adsorption capacity for Cu2+ was found as 94.34 mg g-1. Thermodynamically, the adsorption process was spontaneous and endothermic. The calculated activation energy for the adsorption was observed as high as 127.94 kJ mol-1. Pedagogically, the experiment was assumed to be important in increasing student understanding of kinetic, equilibrium and thermodynamic concepts.

  1. Selective adsorption of bovine hemoglobin on functional TiO2 nano-adsorbents: surface physic-chemical properties determined adsorption activity

    NASA Astrophysics Data System (ADS)

    Guo, Shiguang; Zhang, Jianghua; Shao, Mingxue; Zhang, Xia; Liu, Yufeng; Xu, Junli; Meng, Hao; Han, Yide

    2015-04-01

    Surface functionalized nanoparticles are efficient adsorbents which have shown good potential for protein separation. In this work, we chose two different types of organic molecules, oleic acid (OA) and 3-glycidoxypropyltrimethoxy silane (GPTMS), to functionalize the surface of TiO2 nanoparticles, and we studied the effects of this modification on their surface physicochemical properties in correlation with their selective adsorption of proteins. The results showed that the surface zeta potential and the surface water wettability of the modified TiO2 were significantly changed in comparison with the original TiO2 nanoparticles. The adsorption activities of bovine hemoglobin (BHb) and bovine serum albumin (BSA) on these functionalized TiO2 samples were investigated under different conditions, including pH values, contact time, ion strength, and initial protein concentration. In comparison with the non-specific adsorption of original TiO2, however, both the OA-TiO2 and GPTMS-TiO2 exhibited increased BHb adsorption and decreased BSA adsorption at the same time. Using a binary protein mixture as the adsorption object, a higher separation factor (SF) was obtained for OA-TiO2 under optimum conditions. The different adsorption activities of BHb and BSA on the modified TiO2 were correlated with different interactions at the protein/solid interface, and the chemical force as well as the electrostatic force played an important role in the selective adsorption process.

  2. Carbon composite lignin-based adsorbents for the adsorption of dyes.

    PubMed

    Wang, Xiaohong; Jiang, Chenglong; Hou, Bingxia; Wang, Yingying; Hao, Chen; Wu, Jingbo

    2018-05-10

    Carbon composite lignin-based adsorbent were prepared through hydrothermal method with glucose as carbon source, calcium lignosulfonate and triethylene tetramine as raw materials, respectively. The optimum synthesis conditions were determined by investigating the addition of carbon and triethylene tetramine. The adsorbent was used for the adsorption of azo dyes Congo red and Eriochrome blue black R, and the five factors affecting the adsorption were discussed, including pH of dyes, initial concentration, adsorption time, adsorption temperature and adsorbent dosage. The corresponding adsorption mechanism such as pseudo first order kinetics, pseudo second order kinetics, intraparticle diffusion, Langmuir adsorption isotherm, Freundlich isotherm, Temkin isotherm, Dubinin-Radushkevich adsorption isotherm, thermodynamics were also studied. When the dye concentration is 40 mg L -1 , Congo red and Eriochrome blue black R dye removal rates reach 99%. Moreover, the adsorption process of two kinds of dyes follow the pseudo second order kinetics and the Langmuir adsorption isotherm. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Time dependent wettability of graphite upon ambient exposure: The role of water adsorption

    NASA Astrophysics Data System (ADS)

    Amadei, Carlo A.; Lai, Chia-Yun; Heskes, Daan; Chiesa, Matteo

    2014-08-01

    We report the temporal evolution of the wettability of highly ordered pyrolytic graphite (HOPG) exposed to environmental conditions. Macroscopic wettability is investigated by static and dynamic contact angles (SCA and DCA) obtaining values comparable to the ones presented in the literature. SCA increases from ˜68° to ˜90° during the first hour of exposure after cleaving, whereas DCA is characterized by longer-scale (24 h) time evolution. We interpret these results in light of Fourier transform infrared spectroscopy, which indicates that the evolution of the HOPG wettability is due to adsorption of molecules from the surrounding atmosphere. This hypothesis is further confirmed by nanoscopic observations obtained by atomic force microscope (AFM)-based force spectroscopy, which monitor the evolution of surface properties with a spatial resolution superior to macroscopic experiments. Moreover, we observe that the results of macro- and nanoscale measurements evolve in similar fashion with time and we propose a quantitative correlation between SCA and AFM measurements. Our results suggest that the cause of the transition in the wettability of HOPG is due to the adsorption of hydrocarbon contaminations and water molecules from the environment. This is corroborated by annealing the HOPG is vacuum conditions at 150°, allowing the desorption of molecules on the surface, and thus re-establishing the initial macro and nano surface properties. Our findings can be used in the interpretation of the wettability of more complicated systems derived from HOPG (i.e., graphene).

  4. Time dependent wettability of graphite upon ambient exposure: The role of water adsorption

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Amadei, Carlo A.; Lai, Chia-Yun; Heskes, Daan

    We report the temporal evolution of the wettability of highly ordered pyrolytic graphite (HOPG) exposed to environmental conditions. Macroscopic wettability is investigated by static and dynamic contact angles (SCA and DCA) obtaining values comparable to the ones presented in the literature. SCA increases from ∼68° to ∼90° during the first hour of exposure after cleaving, whereas DCA is characterized by longer-scale (24 h) time evolution. We interpret these results in light of Fourier transform infrared spectroscopy, which indicates that the evolution of the HOPG wettability is due to adsorption of molecules from the surrounding atmosphere. This hypothesis is further confirmedmore » by nanoscopic observations obtained by atomic force microscope (AFM)-based force spectroscopy, which monitor the evolution of surface properties with a spatial resolution superior to macroscopic experiments. Moreover, we observe that the results of macro- and nanoscale measurements evolve in similar fashion with time and we propose a quantitative correlation between SCA and AFM measurements. Our results suggest that the cause of the transition in the wettability of HOPG is due to the adsorption of hydrocarbon contaminations and water molecules from the environment. This is corroborated by annealing the HOPG is vacuum conditions at 150°, allowing the desorption of molecules on the surface, and thus re-establishing the initial macro and nano surface properties. Our findings can be used in the interpretation of the wettability of more complicated systems derived from HOPG (i.e., graphene)« less

  5. Adsorption of malachite green by magnetic litchi pericarps: A response surface methodology investigation.

    PubMed

    Zheng, Hao; Qi, Jinqiu; Jiang, Ruixue; Gao, Yan; Li, Xiaochen

    2015-10-01

    In this work, we synthesized a novel magnetic adsorbent containing litchi pericarps, denoted as MLP, for the removal of malachite green (MG) from solution. The factors influencing MG adsorption, such as contact time, adsorbent dosage, and initial dye concentration, were optimized using the Box-Behnken response surface methodology (RSM). The adsorption isotherms as well as the kinetics and thermodynamics of the adsorption of MG onto MLP are discussed. The results showed that MLP has a maximum adsorption efficiency of 99.5% when the temperature, pH, contact time, adsorbent dosage, and initial MG concentration were optimally set as 25 °C, 6.0, 66.69 min, 5.14 g/L, and 150 mg/L, respectively. The best model to describe this process is the Langmuir isotherm, with the maximum adsorption capacity being 70.42 mg/g. In addition, the kinetics of MG adsorption onto MLP followed a pseudo-second-order model; moreover, thermodynamic analysis suggested that MG adsorption onto MLP is spontaneous and endothermic. Finally, it was found that the new magnetic adsorbent can be separated easily and rapidly from mixed solutions in the presence of an external magnetic field. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Removal of cesium from simulated liquid waste with countercurrent two-stage adsorption followed by microfiltration.

    PubMed

    Han, Fei; Zhang, Guang-Hui; Gu, Ping

    2012-07-30

    Copper ferrocyanide (CuFC) was used as an adsorbent to remove cesium. Jar test results showed that the adsorption capacity of CuFC was better than that of potassium zinc hexacyanoferrate. Lab-scale tests were performed by an adsorption-microfiltration process, and the mean decontamination factor (DF) was 463 when the initial cesium concentration was 101.3μg/L, the dosage of CuFC was 40mg/L and the adsorption time was 20min. The cesium concentration in the effluent continuously decreased with the operation time, which indicated that the used adsorbent retained its adsorption capacity. To use this capacity, experiments on a countercurrent two-stage adsorption (CTA)-microfiltration (MF) process were carried out with CuFC adsorption combined with membrane separation. A calculation method for determining the cesium concentration in the effluent was given, and batch tests in a pressure cup were performed to verify the calculated method. The results showed that the experimental values fitted well with the calculated values in the CTA-MF process. The mean DF was 1123 when the dilution factor was 0.4, the initial cesium concentration was 98.75μg/L and the dosage of CuFC and adsorption time were the same as those used in the lab-scale test. The DF obtained by CTA-MF process was more than three times higher than the single-stage adsorption in the jar test. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Time-resolved chromatographic analysis and mechanisms in adsorption and catalysis.

    PubMed

    Roubani-Kalantzopoulou, Fani

    2009-03-06

    The main object of this review is the study of fundamentals of adsorption and heterogeneous catalysis, a benefit for the understanding of adsorptive and catalytic properties. This work aims to define and record, with the utmost accuracy, the phenomena and the possible reactions. A new methodology for the study of the adsorption is presented, which is a version of the well-known inverse gas chromatography. This reversed-flow inverse gas chromatography (RF-IGC) is technically very simple, and it is combined with a mathematical analysis that gives the possibility for the estimation of various physicochemical parameters related to adsorbent or catalyst characterization, under conditions compatible with the operation of real adsorbents and catalysts. On this base, this methodology has been successfully applied to the study of the impact of air pollutants, volatile organic and/or inorganic, on many solids such as marbles, ceramics, oxide-pigments of works of art, building materials, authentic statues of the Greek Archaeological Museums. Moreover, this methodology proved to be a powerful tool for studying the topography of active sites of heterogeneous surfaces in the nano-scale domain. Thus, some very important local quantities for the surface chemistry have been determined experimentally for many solids including thin films. These physicochemical local quantities (among which adsorption energy and entropy, surface diffusion coefficient, probability density function) have been determined from the experimental pairs of height of extra chromatographic peaks and time by a nonlinear least-squares method, through personal computer programs written in GW BASIC and lately in FORTRAN. Through the time-resolved analysis the surface characterization of the examined materials took place. In addition, the kinetic constants responsible for adsorption/desorption and surface chemical reactions have also been calculated. Thus, important answers have been provided to the following

  8. Binary gaseous mixture and single component adsorption of methane and argon on exfoliated graphite

    NASA Astrophysics Data System (ADS)

    Russell, Brice Adam

    Exfoliated graphite was used as a substrate for adsorption of argon and methane. Adsorption experiments were conducted for both equal parts mixtures of argon and methane and for each gas species independently. The purpose of this was to compare mixture adsorption to single component adsorption and to investigate theoretical predictions concerning the kinetics of adsorption made by Burde and Calbi.6 In particular, time to reach pressure equilibrium of a single dose at a constant temperature for the equal parts mixture was compared to time of adsorption for each species by itself. It was shown that mixture adsorption is a much more complex and time consuming process than single component adsorption and requires a much longer amount of time to reach equilibrium. Information about the composition evolution of the mixture during the times when pressure was going toward equilibrium was obtained using a quadrupole mass spectrometer. Evidence for initial higher rate of adsorption for the weaker binding energy species (argon) was found as well as overall composition change which clearly indicated a higher coverage of methane on the graphite sample by the time equilibration was reached. Effective specific surface area of graphite for both argon and methane was also determined using the Point-B method.2

  9. Adsorption of Acid Blue 25 dye by bentonite and surfactant modified bentonite

    NASA Astrophysics Data System (ADS)

    Jeeva, Mark; Wan Zuhairi, W. Y.

    2018-04-01

    Adsorption of Acid Blue (AB 25) from water via batch adsorption experiments onto Na-Bentonite (NB) and CTAB-modified bentonite (CTAB-Ben) was investigated. Studies concerning the factors influencing the adsorption capacities of NB and CTAB-Ben, such as initial dye concentration, adsorbent dosage, pH, contact time and temperature were investigated and discussed. The results revealed that CTAB-modified bentonite demonstrated high adsorption capacities toward acid dyes, while NB exhibited sorption capacities lower than CTAB-Ben. The maximum adsorption efficiency was found to be 50% at an AB 25 concentration of 50 mg/L, adsorbent dosage of 1.8 g/L, reaction time of 90 min and equilibrium pH of 11. The results of isotherm study fit the Langmuir and Freundlich models (R2 > 0.93) and (R2 > 0.9) respectively.

  10. Heavy metal adsorption changes of EAF steel slag after phosphorus adsorption.

    PubMed

    Song, Guanling; Cao, Lijing; Chen, Xiao; Hou, Wenhua; Wang, Qunhui

    2012-01-01

    A kind of electric arc furnace (EAF) steel slag was phosphated, and its isothermal and dynamic adsorptions of copper, cadmium, and lead ions were measured to determine if heavy metal adsorption changes after phosphorus adsorption. The surface area increased greatly after the slag was phosphated. Isothermal adsorption experiments showed that the theoretical Q(max) of the EAF steel slag on Cu(2+), Cd(2+), and Pb(2+) improved 59, 50, and 89% respectively after it was phosphated. Dynamic adsorption results showed that the greatest adsorption capacities of unit volume of Cu(2+), Cd(2+), and Pb(2+) were 2.2, 1.8, and 1.8 times that of the column packed with original EAF steel slag when the column was packed with phosphate EAF steel slag at the same heavy metal ion concentration. The breakthrough time, the exhaustion time and elution efficiency of the column also increased when the column was packed with phosphated EAF steel slag compared with that packed with original EAF steel slag. Phosphorus adsorption could further improve the heavy metal ion adsorption of the EAF steel slag.

  11. Adsorption characteristics of hexavalent chromium on HCB/TiO2

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Zhang, Yonggang

    2014-10-01

    Sol-gel method was adopted to prepare HCB/TiO2 and its adsorption ability of hexavalent chromium, Cr(VI), and removal from aqueous solution were investigated. The samples were characterized by Power X-ray diffraction (XRD) and a transmission electron microscope (TEM) which showed that the TiO2 was deposited on the surface of HCB. FTIR was used to identify the changes of the surface functional groups before and after adsorption. Potentiometric titration method was used to characterize the zero charge (pHpzc) characteristics of the surface of HCB/TiO2 which showed more acidic functional groups containing. Batch experiments showed that initial pH, absorbent dosage, contact time and initial concentration of Cr(VI) were important parameters for the Cr(VI) adsorption studies. The Freundlich isotherm model better reflected the experimental data better. Cr(VI) adsorption process followed the pseudo-second order kinetic model, which illustrated chemical adsorption. The thermodynamic parameters, such as Gibbs free energy (ΔG), changes in enthalpy change (ΔH) and changes in entropy change (ΔS) were also evaluated. Negative value of free energy occurred at temperature range of 25-45 °C, so Cr(VI) adsorption by HCB/TiO2 is spontaneous. Desorption results showed that the adsorption capacity could maintain 80% after five cycles. The maximum adsorption capacity for Cr(VI) was at 27.33 mg g-1 in an acidic medium, of which the value is worth comparable with other low-cost adsorbents.

  12. Batch and fixed-bed adsorption of tartrazine azo-dye onto activated carbon prepared from apricot stones

    NASA Astrophysics Data System (ADS)

    Albroomi, H. I.; Elsayed, M. A.; Baraka, A.; Abdelmaged, M. A.

    2017-07-01

    This work describes the potential of utilizing prepared activated carbon from apricot stones as an efficient adsorbent material for tartrazine (TZ) azo-dye removal in a batch and dynamic adsorption system. The results revealed that activated carbons with well-developed surface area (774 m2/g) and pore volume (1.26 cm3/g) can be manufactured from apricot stones by H3PO4 activation. In batch experiments, effects of the parameters such as initial dye concentration and temperature on the removal of the dye were studied. Equilibrium was achieved in 120 min. Adsorption capacity was found to be dependent on the initial concentration of dye solution, and maximum adsorption was found to be 76 mg/g at 100 mg/L of TZ. The adsorption capacity at equilibrium ( q e) increased from 22.6 to 76 mg/g with an increase in the initial dye concentrations from 25 to 100 mg/L. The thermodynamic parameters such as change in free energy (Δ G 0), enthalpy (Δ H 0) and entropy (Δ S 0) were determined and the positive value of (Δ H) 78.1 (K J mol-1) revealed that adsorption efficiency increased with an increase in the process temperature. In fixed-bed column experiments, the effect of selected operating parameters such as bed depth, flow rate and initial dye concentration on the adsorption capacity was evaluated. Increase in bed height of adsorption columns leads to an extension of breakthrough point as well as the exhaustion time of adsorbent. However, the maximum adsorption capacities decrease with increases of flow rate. The breakthrough data fitted well to bed depth service time and Thomas models with high coefficient of determination, R 2 ≥ 94.

  13. Native, acidic pre-treated and composite clay efficiency for the adsorption of dicationic dye in aqueous medium.

    PubMed

    Ehsan, Asma; Bhatti, Haq Nawaz; Iqbal, Munawar; Noreen, Saima

    2017-02-01

    Environmental applications of composites have attracted the interests of researchers due to their excellent adsorption efficiency for pollutants. Native, HCl pre-treated clay and MnFe 2 O 4 /clay composite were investigated as an adsorbent for removal of methyl green from aqueous solution. The adsorption behaviors of dye onto native, HCl pre-treated and composite clays were studied as a function of contact time, adsorbent dose, pH, initial dye concentration and temperature. Maximum dye adsorption of 44 mg/g was achieved at pH of 8, contact time 40 min, adsorbent dose 0.20 g/L and initial dye concentration of 125 mg/L using clay composite. The Langmuir isotherm and pseudo-second-order kinetic model best explained the methyl green dye adsorption onto clay adsorbents. Thermodynamic parameters revealed the endothermic and spontaneous adsorption nature of dye. From results, it is concluded that clay has potential for adsorbing methyl green and can be used for the removal of dyes from industrial effluents.

  14. Enhanced fluoride adsorption by nano crystalline γ-alumina: adsorption kinetics, isotherm modeling and thermodynamic studies

    NASA Astrophysics Data System (ADS)

    Chinnakoti, Prathibha; Chunduri, Avinash L. A.; Vankayala, Ranganayakulu K.; Patnaik, Sandeep; Kamisetti, Venkataramaniah

    2017-09-01

    Nano materials in particular nano oxides with enhanced surface area and an excellent catalytic surface serve as potential adsorbents for defluoridation of water. In the present study nano γ-alumina was synthesized through a simple and low cost, surfactant assisted solution combustion method. As synthesized material was characterized by XRD and FESEM for its phase, size and morphological characteristics. Surface properties have been investigated by BET method. Nano γ-alumina was further used for a detailed adsorption study to remove fluoride from water. Batches of experiments were performed at various experimental conditions such as solution pH, adsorbent dose, initial fluoride concentration and contact time to test the defluoridation ability of γ-alumina. Fluoride Adsorption by nano sized γ-alumina was rapid and reached equilibrium within two hours. The adsorption worked well at pH 4.0, where ˜96 % of fluoride was found to be adsorbed on adsorbent. It was possible to reduce fluoride levels to as low as 0.3 mg/L (within the safe limit of WHO: ≤1.5 mg/L) from an initial fluoride levels of 10 mg/L. This could be achieved using a very small quantity, 1 g/L of γ-alumina at pH 4 within 1 h of contact time. Defluoridation capacity of nano γ-alumina was further investigated by fitting the equilibrium data to various isotherm as well as kinetic models. The present study revealed that γ-alumina could be an efficient adsorbent for treating fluoride contaminated water.

  15. Apparatus for thermal swing adsorption and thermally-enhanced pressure swing adsorption

    DOEpatents

    Wegeng, Robert S.; Rassat, Scot D.; Stenkamp, Victoria S.; TeGrotenhuis, Ward E.; Matson, Dean W.; Drost, M. Kevin; Viswanathan, Vilayanur V.

    2005-12-13

    The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

  16. Method for thermal swing adsorption and thermally-enhanced pressure swing adsorption

    DOEpatents

    Wegeng, Robert S.; Rassat, Scot D.; Stenkamp, Victoria S.; TeGrotenhuis, Ward E.; Matson, Dean W.; Drost, M. Kevin; Viswanathan, Vilayanur V.

    2003-10-07

    The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

  17. Adsorption of Cu(II) Ions in Aqueous Solutions by HCl Activated Carbon of Oil Palm

    NASA Astrophysics Data System (ADS)

    Muslim, A.; Syamsuddin, Y.; Salamun, A.; Abubakar; Ramadhan, D.; Peiono, D.

    2017-06-01

    Activated carbon was prepared from oil palm empty fruit bunch (OPEFB) by pyrolysis at 873.15 K in a furnace and chemical activation using 0.01 M HCl. Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy and BET (Brunauer, Emmett and Teller) surface area analyses were taken into account to investigate the chemical functional group, to characterise the surface morphology and to determine total surface area the OPEFB AC, respectively. Experiments in batch mode were conducted to investigate Cu(II) adsorption capacity by the OPEFB AC whereas the system consisted of 1 g the OPEFB AC in 100 mL Cu(II) aqueous solution with initial concentration in the range of 10-70 mg/L, magnetic stirring at 75 rpm, room temperature of 300.15 K (± 2 K), at 1 atm and neutral pH over contact time in the range of 0-150 min. As the result, Cu(II) adsorption capacity increased exponentially over contact time and initial concentration. The Cu(II) adsorption kinetics followed the pseudo second order kinetics with the correlation coefficients (R 2), kinetics rate constant and equilibrium adsorption capacity being 0.98, 4.81 mg/g and 0.15/min, respectively for initial Cu(II) concentration being 58.71 mg/L. In addition, Cu(II) adsorption isotherm followed the Langmuir equation with the R2 value, the mono-layer and over-all adsorption capacity being 0.99, 5.92 mg/g and 0.17 L/mg, respectively.

  18. Adsorption kinetics of c-Fos and c-Jun to air-water interfaces.

    PubMed

    Del Boca, Maximiliano; Nobre, Thatyane Morimoto; Zaniquelli, Maria Elisabete Darbello; Maggio, Bruno; Borioli, Graciela A

    2007-11-01

    The kinetics of adsorption to air-water interfaces of the biomembrane active transcription factors c-Fos, c-Jun and their mixtures is investigated. The adsorption process shows three distinct stages: a lag time, a fast pseudo zero-order stage, and a halting stage. The initial stage determines the course of the process, which is concentration dependent until the end of the fast stage. We show that c-Fos has faster adsorption kinetics than c-Jun over all three stages and that the interaction between both proteins is apparent in the adsorption profiles of the mixtures. Protein molecular reorganization at the interface determines the transition to the final adsorption stage of the pure proteins as well as that of the mixtures.

  19. Post-combustion CO2 capture with activated carbons using fixed bed adsorption

    NASA Astrophysics Data System (ADS)

    Al Mesfer, Mohammed K.; Danish, Mohd; Fahmy, Yasser M.; Rashid, Md. Mamoon

    2018-03-01

    In the current work, the capturing of carbon dioxide from flue gases of post combustion emission using fixed bed adsorption has been carried out. Two grades of commercial activated carbon (sorbent-1 and sorbent-2) were used as adsorbent. Feed consisting of CO2 and N2 mixture was used for carrying out the adsorption. The influence of bed temperature, feed rate, equilibrium partial pressure and initial % CO2 in feed were considered for analyzing adsorption-desorption process. It was found that the total adsorption-desorption cycle time decreases with increased column temperature and feed rates. The time required to achieve the condition of bed saturation decreases with increased bed temperature and feed rates. The amount of CO2 adsorbed/Kg of the adsorbent declines with increased bed temperature with in studied range for sorbent-1 and sorbent-2. It was suggested that the adsorption capacity of the both the sorbents increases with increased partial pressure of the gas.

  20. The adsorption and reaction of adenine nucleotides on montmorillonite

    NASA Technical Reports Server (NTRS)

    Ferris, James P.; Hagan, William J., Jr.

    1986-01-01

    The binding of AMP to Zn(2+)-montmorillonite is investigated in the presence of salts and Good's zwitterion buffers, PIPES and MES. The initial concentrations of nucleotide and the percent adsorbtion are used to calculate the adsorption isotherms, and the Langmuir adsorption equation is used for the analysis of data. The adsorption coefficient was found to be three times greater in the presence of 0.2 M PIPES than in its absence. In addition, basal spacings measured by X-ray diffraction were increased by the buffer. These results are interpreted in terms of a model in which the adsorption of AMP is mediated by a Zn(2+) complex of PIPES in different orientations in the interlamellar region of the montmorillonite. Mixed ligand complexes of this type are reminiscent of the complexes observed between metal ions and biological molecules in living systems.

  1. Cadmium-109 Radioisotope Adsorption onto Polypyrrole Coated Sawdust of Dryobalanops aromatic: Kinetics and Adsorption Isotherms Modelling

    PubMed Central

    Olatunji, Michael Adekunle; Khandaker, Mayeen Uddin; Amin, Yusoff Mohd; Mahmud, Habibun Nabi Muhammad Ekramul

    2016-01-01

    A radiotracer study was conducted to investigate the removal characteristics of cadmium (109Cd) from aqueous solution by polypyrrole/ sawdust composite. Several factors such as solution pH, sorbent dosage, initial concentration, contact time, temperature and interfering metal ions were found to have influence on the adsorption process. The kinetics of adsorption was relatively fast, reaching equilibrium within 3 hours. A lowering of the solution pH reduced the removal efficiency from 99.3 to ~ 46.7% and an ambient temperature of 25°C was found to be optimum for maximum adsorption. The presence of sodium and potassium ions inhibited 109Cd removal from its aqueous solution. The experimental data for 109Cd adsorption showed a very good agreement with the Langmuir isotherm and a pseudo-first order kinetic model. The surface condition of the adsorbent before and after cadmium loading was investigated using BET, FESEM and FTIR. Considering the low cost of the precursor’s materials and the toxicity of 109Cd radioactive metal, polypyrrole synthesized on the sawdust of Dryobalanops aromatic could be used as an efficient adsorbent for the removal of 109Cd radioisotope from radionuclide-containing effluents. PMID:27706232

  2. Kinetics of Cd(ii) adsorption and desorption on ferrihydrite: experiments and modeling.

    PubMed

    Liang, Yuzhen; Tian, Lei; Lu, Yang; Peng, Lanfang; Wang, Pei; Lin, Jingyi; Cheng, Tao; Dang, Zhi; Shi, Zhenqing

    2018-05-15

    The kinetics of Cd(ii) adsorption/desorption on ferrihydrite is an important process affecting the fate, transport, and bioavailability of Cd(ii) in the environment, which was rarely systematically studied and understood at quantitative levels. In this work, a combination of stirred-flow kinetic experiments, batch adsorption equilibrium experiments, high-resolution transmission electron microscopy (HR-TEM), and mechanistic kinetic modeling were used to study the kinetic behaviors of Cd(ii) adsorption/desorption on ferrihydrite. HR-TEM images showed the open, loose, and sponge-like structure of ferrihydrite. The batch adsorption equilibrium experiments revealed that higher pH and initial metal concentration increased Cd(ii) adsorption on ferrihydrite. The stirred-flow kinetic results demonstrated the increased adsorption rate and capacity as a result of the increased pH, influent concentration, and ferrihydrite concentration. The mechanistic kinetic model successfully described the kinetic behaviors of Cd(ii) during the adsorption and desorption stages under various chemistry conditions. The model calculations showed that the adsorption rate coefficients varied as a function of solution chemistry, and the relative contributions of the weak and strong ferrihydrite sites for Cd(ii) binding varied with time at different pH and initial metal concentrations. Our model is able to quantitatively assess the contributions of each individual ferrihydrite binding site to the overall Cd(ii) adsorption/desorption kinetics. This study provided insights into the dynamic behavior of Cd(ii) and a predictive modeling tool for Cd(ii) adsorption/desorption kinetics when ferrihydrite is present, which may be helpful for the risk assessment and management of Cd contaminated sites.

  3. Adsorption affinity and selectivity of 3-ureidopropyltriethoxysilane grafted oil palm empty fruit bunches towards mercury ions.

    PubMed

    Kunjirama, Magendran; Saman, Norasikin; Johari, Khairiraihanna; Song, Shiow-Tien; Kong, Helen; Cheu, Siew-Chin; Lye, Jimmy Wei Ping; Mat, Hanapi

    2017-06-01

    This study was conducted to investigate the potential application of oil palm empty fruit branches (OPEFB) as adsorbents to remove organic methylmercurry, MeHg(II), and inorganic Hg(II) from aqueous solution. The OPEFB was functionalized with amine containing ligand namely 3-ureidopropyltriethoxysilane (UPTES) aiming for better adsorption performance towards both mercury ions. The adsorption was found to be dependent on initial pH, initial concentraton, temperatures, and contact time. The maximum adsorption capacities (Q m.exp ) of Hg(II) adsorption onto OPEFB and UPTES-OPEFB were 0.226 and 0.773 mmol/g, respectively. The Q m.exp of MeHg(II) onto OPEFB, however, was higher than UPTES-OPEFB. The adsorption kinetic data obeyed the Elovich model and the adsorption was controlled by the film-diffusion step. The calculated thermodynamic parameters indicate an endothermic adsorption process. Adsorption data analysis indicates that the adsorption mechanism may include ion-exchange, complexation, and physisorption interactions. The potential applications of adsorbents were demonstrated using oilfield produced water and natural gas condensate. The UPTES-OPEFB offered higher selectivity towards both mercury ions than OPEFB. The regenerability studies indicated that the adsorbent could be reused for multiple cycles.

  4. Synthesis of Magnesium Ferrites for the Adsorption of Congo Red from Aqueous Solution Using Batch Studies

    NASA Astrophysics Data System (ADS)

    Erdawati, E.; Darsef, D.

    2018-04-01

    A sol gel method with citric acid as an anionic surfactant was used to fabricate nano magnesium ferrites (MgFe2O4) under different calcination temperatures for 2h, respectively. The microstructure and surface morphology of magnesium ferrite powder were characterized by FTIR, XRD, SEM, and BET. The results of this study are useful for adsorption Congo red. The results showed that increasing solution pH and extending contact time are favorable for improving adsorption efficiency. with initial Congo red concentration of 50 mg/L and 100 mg/L. Adsorption data fits well with the Langmuir isotherm models with a maximum adsorption capacity (qm) and a Langmuir adsorption equilibrium constant (K) of 65.1 mg/g and 0.090 L/mg, respectively. The adsorption kinetic agrees well with pseudo second order model with the pseudo second rate constants (K2) of 0.0468 and0.00189 g/mg/min for solutions with initial congo red of 50 and 100 mg/L, respectively

  5. Investigation of copper (Cu2+) adsorption performances and gamma radiation dose effect of polymeric hydrogel

    NASA Astrophysics Data System (ADS)

    Hassan, Safia; Yasin, Tariq; Imran, Zahid; Batool, Syeda Sitwat

    2018-02-01

    In present study, series of gamma irradiated poly(acrylic acid)/Penytriethoxytrisilane (PTES) based hydrogels were synthesized. The hydrogels were used for the adsorption of Cu2+ from the aqueous solution. Batch adsorption experiments were performed by varying contact time (0-10 hours), pH value (2-6), hydrogels weight (15-155 mg) and initial Cu2+ concentration (0.003-90 mg/L). The results indicated that lowering the gamma irradiation dose (30-15 kGy) and PTES amount (1.65-0.83 μmol) into hydrogel polymeric networks, improved the initial rate of adsorption and final adsorption capacity of hydrogel for Cu2+. AA40/15 had 143.4mg/g Cu2+ adsorption capacity higher than AA80/30 which is 106.0mg/g. Hydrogels exhibited maximum o adsorption capacity for Cu2+ within a wide pH range. All adsorption data was described by the pseudo—first order and second order kinetic model equations and isotherm data by Langmuir model. FTIR spectra analysis before and after adsorption of Cu2+ on the AA hydrogels gave detail analysis of adsorption mechanism. The behavior of adsorption expressed that the enhanced adsorption capacity was due to the porous structure and e presence of functional groups onto surface of adsorbate. It is expected this polymeric hydrogel has potential to work as alternative biomedical sorbents and environmental use as pH altered.

  6. Kinetics of Molybdenum Adsorption and Desorption in Soils.

    PubMed

    Sun, Wenguang; Selim, H Magdi

    2018-05-01

    Much uncertainty exists in mechanisms and kinetics controlling the adsorption and desorption of molybdenum (Mo) in the soil environment. To investigate the characteristics of Mo adsorption and desorption and predict Mo behavior in the vadose zone, kinetic batch experiments were performed using three soils: Webster loam, Windsor sand and Mahan sand. Adsorption isotherms for Mo were strongly nonlinear for all three soils. Strong kinetic adsorption of Mo by all soils was also observed, where the rate of retention was rapid initially and was followed by slow retention behavior with time. The time-dependent Mo sorption rate was not influenced when constant pH was maintained. Desorption or release results indicated that there were significant fractions of Mo that appeared to be irreversible or slowly reversibly sorbed by Windsor and Mahan. X-ray absorption near edge structure (XANES) analysis for Windsor and Mahan soils indicated that most of Mo had been bound to kaolinite, whereas Webster had similar XANES features to those of Mo sorbed to montmorillonite. A sequential extraction procedure provided evidence that a significant amount of Mo was irreversibly sorbed. A multireaction model (MRM) with nonlinear equilibrium and kinetic sorption parameters was used to describe the adsorption-desorption kinetics of Mo on soils. Our results demonstrated that a formulation of MRM with two sorption sites (equilibrium and reversible) successfully described Mo adsorption-desorption data for Webster loam, and an additional irreversible reaction phase was recommended to describe Mo desorption or release with time for Windsor and Mahan soils. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  7. Adsorption and removal of clofibric acid and diclofenac from water with MIEX resin.

    PubMed

    Lu, Xian; Shao, Yisheng; Gao, Naiyun; Chen, Juxiang; Zhang, Yansen; Wang, Qiongfang; Lu, Yuqi

    2016-10-01

    This study demonstrates the use of MIEX resin as an efficient adsorbent for the removal of clofibric acid (CA) and diclofenac (DCF). The adsorption performance of CA and DCF are investigated by a batch mode in single-component or bi-component adsorption system. Various factors influencing the adsorption of CA and DCF, including initial concentration, contact time, adsorbent dosage, initial solution pH, agitation speed, natural organic matter and coexistent anions are studied. The Langmuir model can well describe CA adsorption in single-component system, while the Freundlich model gives better fitting in bi-component system. The DCF adsorption can be well fitted by the Freundlich model in both systems. Thermodynamic analyses show that the adsorption of CA and DCF is an endothermic (ΔH(o) > 0), entropy driven (ΔS(o) > 0) process and more randomness exists in the DCF adsorption process. The values of Gibbs free energy (ΔG(o) < 0) indicate the adsorption of DCF is spontaneous but nonspontaneous (ΔG(o) > 0) for CA adsorption. The kinetic data suggest the adsorption of CA and DCF follow the pseudo-first-order model in both systems and the intra-particle is not the unique rate-limiting step. The adsorption process is controlled simultaneously by external mass transfer and surface diffusion according to the surface diffusion modified Biot number (Bis) ranging from 1.06 to 26.15. Moreover, the possible removal mechanism for CA and DCF is respectively proposed based on the ion exchange stoichiometry. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Removal of zinc (II) ion from aqueous solution by adsorption onto activated palm midrib bio-sorbent

    NASA Astrophysics Data System (ADS)

    Mulana, F.; Mariana; Muslim, A.; Mohibah, M.; Halim, K. H. Ku

    2018-03-01

    In this paper, palm midrib that was activated with mixed citric acid and tartaric acid as biosorbent was used to remove Zn (II) ion from aqueous solution. The aim of this research is to activate palm midrib by using a mixed citric acid and tartaric acid and to determine adsorption capacity of activated palm midrib biosorbent on Zn (II) ion uptake from aqueous solution. The effect of several parameters such as contact time, initial Zn (II) ion concentration and activator concentration on the degree of Zn (II) ion removal was examined. Atomic Absorption Spectroscopy method was performed to determine adsorbed amount of Zn (II) ion into activated biosorbent. The result showed that the adsorption process was relatively not so fast and equilibrium was reached after contact time of 120 min. The adsorption capacity of biosorbent reached a maximum when the concentration of mixed citric acid and tartaric acid was 1.6 M. The optimum adsorption capacity was 5.72 mg/g. The result was obtained on initial Zn (II) ion concentration of 80 ppm for 120-min contact time. Langmuir isotherm was found as the best fit for the equilibrium data indicating homogeneous adsorption of metal ions onto the biosorbent surface.

  9. Adsorption of Congo red dye onto antimicrobial terephthaloyl thiourea cross-linked chitosan hydrogels.

    PubMed

    El-Harby, Nouf F; Ibrahim, Shaimaa M A; Mohamed, Nadia A

    2017-11-01

    Adsorption capacity of three antimicrobial terephthaloyl thiourea cross-linked chitosan hydrogels for Congo red dye removal from its aqueous solution has been investigated for the first time in this work. These hydrogels were prepared by reacting chitosan with various amounts of terephthaloyl diisothiocyanate cross-linker. The effect of the hydrogel structural variations and several dye adsorption processing parameters to achieve the best adsorption capacity were investigated. The hydrogels' structural variations were obtained by varying their terephthaloyl thiourea moieties content. The processing variables included initial concentration of the dye solution, temperature and time of exposure to the dye. The adsorption kinetics and isotherms showed that the sorption processes were better fitted by the pseudo-second-order equation and the Langmuir equation, respectively. On the basis of the Langmuir analysis Congo red dye gave the maximum sorption capacity of 44.248 mg/g. The results obtained confirmed that the sorption phenomena are most likely to be controlled by chemisorption process. The adsorption reaction was endothermic and spontaneous according to the calculated results of adsorption thermodynamics.

  10. Terahertz time-domain spectroscopy of submonolayer water adsorption in hydrophilic silica aerogel.

    PubMed

    Zhang, Jiangquan; Grischkowsky, Daniel

    2004-05-01

    We report a terahertz time-domain spectroscopy study of the adsorption of water in hydrophilic silica aerogel. The adsorbed water is in submonolayer form and shows properties of index of refraction similar to those of bulk water but different absorption properties.

  11. Adsorption and Desorption of Nickel(II) Ions from Aqueous Solution by a Lignocellulose/Montmorillonite Nanocomposite

    PubMed Central

    Zhang, Xiaotao; Wang, Ximing

    2015-01-01

    A new and inexpensive lignocellulose/montmorillonite (LNC/MMT) nanocomposite was prepared by a chemical intercalation of LNC into MMT and was subsequently investigated as an adsorbent in batch systems for the adsorption-desorption of Ni(II) ions in an aqueous solution. The optimum conditions for the Ni(II) ion adsorption capacity of the LNC/MMT nanocomposite were studied in detail by varying parameters such as the initial Ni(II) concentration, the solution pH value, the adsorption temperature and time. The results indicated that the maximum adsorption capacity of Ni(II) reached 94.86 mg/g at an initial Ni(II) concentration of 0.0032 mol/L, a solution pH of 6.8, an adsorption temperature of 70°C, and adsorption time of 40 min. The represented adsorption kinetics model exhibited good agreement between the experimental data and the pseudo-second-order kinetic model. The Langmuir isotherm equation best fit the experimental data. The structure of the LNC/MMT nanocomposite was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), whereas the adsorption mechanism was discussed in combination with the results obtained from scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectroscopy analyses (FTIR). The desorption capacity of the LNC/MMT nanocomposite depended on parameters such as HNO3 concentration, desorption temperature, and desorption time. The satisfactory desorption capacity of 81.34 mg/g was obtained at a HNO3 concentration, desorption temperature, and desorption time of 0.2 mol/L, 60 ºC, and 30 min, respectively. The regeneration studies showed that the adsorption capacity of the LNC/MMT nanocomposite was consistent for five cycles without any appreciable loss in the batch process and confirmed that the LNC/MMT nanocomposite was reusable. The overall study revealed that the LNC/MMT nanocomposite functioned as an effective adsorbent in the detoxification of Ni

  12. A comprehensive adsorption study and modeling of antibiotics as a pharmaceutical waste by graphene oxide nanosheets.

    PubMed

    Rostamian, Rahele; Behnejad, Hassan

    2018-01-01

    The adsorption behavior of tetracycline (TCN), doxycycline (DCN) as the most common antibiotics in veterinary and ciprofloxacin (CPN) onto graphene oxide nanosheets (GOS) in aqueous solution was evaluated. The four factors influencing the adsorption of antibiotics (initial concentration, pH, temperature and contact time) were studied. The results showed that initial pH ∼ 6 to 7 and contact time ∼ 100 - 200min are optimum for each drug. The monolayer adsorption capacity was reduced with the increasing temperature from 25°C to 45°C. Non-linear regressions were carried out in order to define the best fit model for every system. To do this, eight error functions were applied to predict the optimum model. Among various models, Hill and Toth isotherm models represented the equilibrium adsorption data of antibiotics while the kinetic data were well fitted by pseudo second-order (PSO) kinetic model (DCN and TCN) and Elovich (CPN) models. The maximum adsorption capacity (q max ) is found to be in the following order: CPN > DCN > TCN, obtained from sips equation at the same temperature. The GOS shows highest adsorption capacity towards CPN up to 173.4mgg -1 . The study showed that GOS can be removed more efficiently from water solution. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Adsorption of intrinsically disordered barnacle adhesive proteins on silica surface

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoqiang; Wang, Chao; Xu, Baomei; Wei, Junting; Xiao, Yang; Huang, Fang

    2018-01-01

    The adsorption of recombinant barnacle proteins Bacp19k and Mrcp19k on hydrophilic silica surface was characterized by spectroscopic ellipsometry in artificial seawater (pH = 8.2). They are homologous adhesive proteins destined for underwater adhesion but bear opposite net charges in seawater. As assessed with their primary and secondary structures, both proteins are intrinsically disordered and thus distinct from globular proteins that have dominated research in the field. Different from Mrcp19k, higher initial rate and adsorbed amount were obtained via curve fitting for Bacp19k in kinetic studies, due to favorable charge interactions with silica surface. The good fitting with the same dynamic model also indicates the formation of monolayer coverage in both cases. The two adsorption isotherms of Bacp19k and Mrcp19k are different in the initial change and maximum adsorption level, indicating different protein-surface affinities and charge interactions. Each isotherm fits the Langmuir model well, which is commonly used to describe monolayer adsorption, thus consistent with the predication from kinetic fitting. To further examine the effect of electrostatic interaction on the adsorption, the isotherm of the 1:1 mixture of Bacp19k and Mrcp19k was also constructed, which showed a higher correlation fit for Jovanovic than for Langmuir model. The presence of electrostatic attraction between Bacp19k and Mrcp19k deviated from one of the required conditions for Langmuir behavior, which may also result in the highest coadsorption level but slowest initial change among the three isotherms. The surface state of the adhesive proteins and the change with adsorption time were also examined by atomic force microscopy. The results thus obtained are in good agreement with the corresponding ellipsometric measurement.

  14. Adsorption of methyl orange from aqueous solution using chitosan/diatomite composite.

    PubMed

    Zhao, Peng; Zhang, Runhu; Wang, Jianglin

    2017-04-01

    A novel chitosan/diatomite composite was prepared by a simple mixture in the mass ratio to remove methyl orange (MO) from aqueous media in this study. The composite adsorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy analysis. The parameters to influence the adsorption of MO were studied under such conditions as kinetics, adsorption isotherm, pH effect, and thermodynamics. The results revealed that adsorption of MO was initially rapid and the equilibrium time was reached after 40 min. The optimal value of the pH was 5.0 for better adsorption. The equilibrium data were well fitted to the Langmuir isotherm compared to the Freundlich isotherm, and exhibited the highest capacity and a removal rate of 88.37% under an initial dye concentration of 50 mg/L. The kinetic data were well described by the pseudo-second order model. The thermodynamic calculations revealed that the sorption was viable, spontaneous, and exothermic under the conditions studied. In addition, the chitosan/diatomite composite had good adsorption and desorption performance with respect to reusability after six cycles. These results showed that the chitosan/diatomite could be considered as a potential adsorbent for the removal of MO in aqueous solution.

  15. Batch versus column modes for the adsorption of radioactive metal onto rice husk waste: conditions optimization through response surface methodology.

    PubMed

    Kausar, Abida; Bhatti, Haq Nawaz; Iqbal, Munawar; Ashraf, Aisha

    2017-09-01

    Batch and column adsorption modes were compared for the adsorption of U(VI) ions using rice husk waste biomass (RHWB). Response surface methodology was employed for the optimization of process variables, i.e., (pH (A), adsorbent dose (B), initial ion concentration (C)) in batch mode. The B, C and C 2 affected the U(VI) adsorption significantly in batch mode. The developed quadratic model was found to be validated on the basis of regression coefficient as well as analysis of variance. The predicted and actual values were found to be correlated well, with negligible residual value, and B, C and C 2 were significant terms. The column study was performed considering bed height, flow rate and initial metal ion concentration, and adsorption efficiency was evaluated through breakthrough curves and bed depth service time and Thomas models. Adsorption was found to be dependent on bed height and initial U(VI) ion concentration, and flow rate decreased the adsorption capacity. Thomas models fitted well to the U(VI) adsorption onto RHWB. Results revealed that RHWB has potential to remove U(VI) ions and batch adsorption was found to be efficient versus column mode.

  16. Simultaneous adsorption of Cu2+ and Acid fuchsin (AF) from aqueous solutions by CMC/bentonite composite.

    PubMed

    Gong, Ning; Liu, Yanping; Huang, Ruihua

    2018-04-21

    Carboxymethyl-chitosan (CMC)/bentonite composite was prepared by the method of membrane-forming, and characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. The simultaneous adsorption of Cu 2+ and Acid fuchsin (AF) applying CMC/bentonite composite as an adsorbent in single or binary systems was investigated. The adsorption study was conducted systematically by varying the ratio of CMC to bentonite, adsorbent dosage, initial pH value, initial Cu 2+ (or AF) concentration, contact time and the interaction of two components in binary solutions. The results showed that the presence of Cu 2+ hindered the adsorption of AF, while the presence of AF almost had no influence on the adsorption of Cu 2+ in binary systems. The adsorption data of Cu 2+ and AF were both suitable for Langmuir isotherm model, and the maximum adsorption capacities of CMC/bentonite composite, according to the Langmuir isotherm model were 81.4 mg/g for Cu 2+ and 253.2 mg/g for AF at 298 K. The pseudo-second-order model could better describe the adsorption process of Cu 2+ and AF. Thermodynamic constant values illustrated that the adsorption of Cu 2+ was endothermic, while the adsorption process of AF was exothermic. Copyright © 2018. Published by Elsevier B.V.

  17. Synthesis of graphene aerogel for adsorption of bisphenol A

    NASA Astrophysics Data System (ADS)

    Trinh, Truong Thi Phuong Nguyet Xuan; Long, Nguyen Huynh Bach Son; Quang, Dong Thanh; Hieu, Nguyen Huu

    2018-04-01

    In this research, graphene aerogel (GA) was synthesized by chemical reduction method using ethylene diamine as a reducing agent. The morphology and properties of GA were characterized by calculating apparent density, Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, and Brunauer-Emmett-Teller (BET) specific surface area. High-performance liquid chromatography (HPLC) was used to quantify the amount of the residual bisphenol A (BPA) concentration. The analysis results showed that GA exhibited low density ranging from 4-8 mg/cm3, hydrophobicity, high porosity, and specific surface area of 1883 m2/g according to BET. The obtained GA was used as an adsorbent for BPA. The effects of pH, contact time, and initial BPA concentration on the adsorption were investigated. The adsorption equilibrium time could be reached within 240 minutes. The adsorption data were well-fitted to pseudo-second-order kinetic equation and Langmuir isotherm model. The maximum adsorption capacity of GA for BPA calculated by the Langmuir model was 185.185 mg/g at pH 7. Accordingly, GA could be considered as promising adsorbents for BPA in water.

  18. Adsorption of crystal violet onto functionalised multi-walled carbon nanotubes: Equilibrium and kinetic studies.

    PubMed

    Sabna, V; Thampi, Santosh G; Chandrakaran, S

    2016-12-01

    Synthetic dyes present in effluent from textile, paper and paint industries contain crystal violet (CV), a known carcinogenic agent. This study investigates the modification of multiwalled carbon nanotubes by acid reflux method and equilibrium and kinetic behaviour of adsorption of CV onto functionalized multi-walled carbon nanotubes (fMWNTs) in batch system. High stability of the fMWNTs suspension in water indicates the hydrophilicity of fMWNTs induced due to the formation of functional groups that make hydrogen bonds with water molecules. fMWNTs were characterized by Fourier Transform Infra Red (FTIR) spectroscopy and the functional groups present on the fMWNTs were confirmed. Characteristic variation was observed in the FTIR spectra of fMWNTs after adsorption of crystal violet onto it. Adsorption characteristics were evaluated as a function of system variables such as contact time, dosage of fMWNTs and initial concentration and pH of the crystal violet solution. Adsorption capacity of fMWNTs and percentage removal of the dye increased with increase in contact time, adsorbent dosage and pH but declined with increase in initial concentration of the dye. fMWNTs showed higher adsorption capacity compared to that of pristine MWNTs. Data showed good fit with the Langmuir and Freundlich isotherm models and the pseudo-second order kinetic model; the maximum adsorption capacity was 90.52mg/g. Kinetic parameters such as rate constants, equilibrium adsorption capacities and regression coefficients were estimated. Results indicate that fMWNTs are an effective adsorbent for the removal of crystal violet from aqueous solution. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Adsorption kinetic and desorption studies of Cd2+ on Multi-Carboxylic-Functionalized Silica Gel

    NASA Astrophysics Data System (ADS)

    Li, Min; Wei, Jian; Meng, Xiaojing; Wu, Zhuqiang; Liang, Xiuke

    2018-01-01

    In the present study, the adsorption behavior of cadmium (II) ion from aqueous solution onto multi-carboxylic-functionalized silica gel (SG-MCF) has been investigated in detail by means of batch and column experiments. Batch experiments were performed to evaluate the effects of contact time on adsorption capacity of cadmium (II) ion. The kinetic data were analyzed on the basis of the pseudo-first-order kinetic and the pseudo-second-order kinetic models and consequently, the pseudo-second-order kinetic can better describe the adsorption process than the pseudo-first-order kinetic model. And the adsorption mechanism of the process was studied by intra-particle and film diffusion, it was found out that the adsorption rate was governed primarily by film diffusion to the adsorption onto the SG-MCF. In addition, column experiments were conducted to assess the effects initial inlet concentration and the flow rate on breakthrough time and adsorption capacity ascertaining the practical applicability of the adsorbent. The results suggest that the total amount of adsorbed cadmium (II) ion increased with declined flow rate and increased the inlet concentration. The adsorption-desorption experiment confirmed that adsorption capacity of cadmium (II) ion didn’t present an obvious decrease after five cycles.

  20. Adsorption kinetic and desorption studies of Cu2+ on Multi-Carboxylic-Functionalized Silica Gel

    NASA Astrophysics Data System (ADS)

    Li, Min; Meng, Xiaojing; Liu, Yushuang; Hu, Xinju; Liang, Xiuke

    2018-01-01

    In the present study, the adsorption behavior of copper (II) ion from aqueous solution onto multi-carboxylic-functionalized silica gel (SG-MCF) has been investigated in detail by means of batch and column experiments. Batch experiments were performed to evaluate the effects of contact time on adsorption capacity of copper (II) ion. The kinetic data were analyzed on the basis of the pseudo-first-order kinetic and the pseudo-second-order kinetic models and consequently, the pseudo-second-order kinetic can better describe the adsorption process than the pseudo-first-order kinetic model. And the adsorption mechanism of the process was studied by intra-particle and film diffusion, it was found out that the adsorption rate was governed primarily by film diffusion to the adsorption onto the SG-MCF. In addition, column experiments were conducted to assess the effects initial inlet concentration and the flow rate on breakthrough time and adsorption capacity ascertaining the practical applicability of the adsorbent. The results suggest that the total amount of adsorbed copper (II) ion increased with declined flow rate and increased the inlet concentration. The adsorption-desorption experiment confirmed that adsorption capacity of copper (II) ion didn’t present an obvious decrease after five cycles.

  1. Adsorption of Benzoic Acid in Aqueous Solution by Bagasse Fly Ash

    NASA Astrophysics Data System (ADS)

    Suresh, S.

    2012-09-01

    This paper reports the studies on the benzoic acid (BA) onto bagasse fly ash (BFA) was studied in aqueous solution in a batch system. Physico-chemical properties including surface area, surface texture of the GAC before and after BA adsorption onto BFA were analysed using X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The optimum initial pH for the adsorption of BA was found to be 5.56. The adsorbent dose was 10 g/l for BFA and the equilibrium time 8 h of reaction. Pseudo first and second order models were used to find the adsorption kinetics. It was found that intraparticle diffusion played important role in the adsorption mechanisms of BA and the adsorption kinetics followed pseudo-second order kinetic model rather than the pseudo first order kinetic model. Isotherm data were generated for BA solution having initial concentrations of BA in the range of 10-200 mg/l for the BFA dosage of 10 g/l at temperatures of 288, 303, and 318 K. The adsorption of BA onto BFA was favorably influenced by an increase in temperature. Equilibrium data were well represented by the Redlich-Peterson isotherm model. Values of the change in entropy ( ΔS 0), heat of adsorption ( ΔH 0) for adsorption of BA on BFA was found to be 120.10 and 19.61 kJ/mol respectively. The adsorption of BA onto BFA was an endothermic reaction. Desorption of BA from BFA was studied by various solvents method. Acetic acid was found to be a better eluant for desorption of BA with a maximum desorption efficiency of 55.2 %. Owing to its heating value, spent BFA can be used as a co-fuel for the production of heat in boiler furnaces.

  2. A Novel Nanocomposite as an Efficient Adsorbent for the Rapid Adsorption of Ni(II) from Aqueous Solution

    PubMed Central

    Wang, Ximing; Chen, Zhangjing

    2017-01-01

    A sulfhydryl-lignocellulose/montmorillonite (SLT) nanocomposite was prepared using a chemical intercalation reaction. The SLT nanocomposite was characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Transmission Electron Microscopy (TEM), the results demonstrated that an intercalated-exfoliated nanostructure was formed in the SLT nanocomposite. Batch experiments were conducted to optimize parameters such as SLT nanocomposite dosage, the initial concentration of Ni(II), solution pH, temperature, and time. The results indicated that the attractive adsorption capacity reached 1134.08 mg/g with 0.05 g of SLT at an initial concentration of Ni(II) of 700 mg/L, solution pH of 5.5, adsorption temperature of 50 °C, and adsorption time of 40 min, meanwhile, the Ni(II) adsorption capacity significantly decreased with the increase in ionic strength. The pseudo-second order kinetic model could describe the whole adsorption process well, and the isotherm adsorption equilibrium conformed to the Freundlich model. The adsorption mechanism of SLT was also discussed by means of FTIR and Energy-Dispersive X-Ray (EDX). Dramatically, the introduction of sulfhydryl achieves the increased activated functional groups content of SLT nanocomposite, leading to remarkably higher adsorption amount on Ni(II). The desorption capacity of SLT was dependent on parameters such as HNO3 concentration, desorption temperature, and ultrasonic desorption time. The satisfactory desorption capacity and desorption efficiency of 458.21 mg/g and 40.40% were obtained at an HNO3 concentration, desorption temperature, and ultrasonic desorption time of 0.4 mol/L, 40 °C, and 30 min, respectively. The regeneration studies showed that the adsorption capacity of SLT was consistent for four cycles without any appreciable loss and confirmed that the SLT was reusable. Owing to such outstanding features, the novel SLT nanocomposite proved the

  3. Acoustic cavitation induced synthesis of zirconium impregnated activated carbon for effective fluoride scavenging from water by adsorption.

    PubMed

    Mullick, Aditi; Neogi, Sudarsan

    2018-07-01

    Environmental concern associated with the side effects of high fluoride content in ground water and surface water has prompted the researchers to look for an efficient, convenient and easy method. Considering the potential of a good adsorbent, present study reports the synthesis of a composite by impregnating zirconium on powdered activated carbon (AC) using ultrasound as the tool for synthesis and applying it for fluoride adsorption from water. The nature of the composite was determined through characterization by scanning electron microscopy (SEM), energy dispersive Xray (EDX), Xray diffraction (XRD), N 2 adsorption analysis (BET) and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The pH pzc (point of zero charge) of the adsorbent was found to be 5.03; with the optimum pH obtained at 4 for adsorption of strong electronegative fluoride ions. The initial fluoride concentration was varied from 2.5 up to 20 mg.L -1 and the maximum adsorption capacity of 5 mg.g -1 was obtained. A maximum fluoride removal of 94.4% was obtained for an initial concentration of 2.5 mg.L -1 within an equilibrium time of 180 min. The adsorption isotherm followed the Langmuir isotherm model indicating a monolayer adsorption process and the adsorption kinetics followed pseudo second order model. The effects of various coexisting ions (HCO 3 - , NO 3 - , SO 4 2- , Cl - ) commonly present in the water were found to have negligible impact on the process performance. Conducting the adsorption-desorption studies for five consecutive cycles for an initial fluoride concentration of 10 mg.L -1 , the removal efficiency reduced from 86.2 to 32.6%. The ultrasonic method provided an easy route to synthesize the composite in less time and significantly reduced energy consumption by more than 96% compared to the conventional method. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Removal of Hexavalent Chromium by Adsorption on Microwave Assisted Activated Carbon Prepared from Stems of Leucas Aspera

    NASA Astrophysics Data System (ADS)

    Shanmugalingam, A.; Murugesan, A.

    2018-05-01

    This study reports adsorption of Cr(VI) ions from aqueous solution using activated carbon that was prepared from stems of Leucas aspera. Eight hundred and fifty watts power of microwave radiation, 12 min of radiation time, 60% of ZnCl2 solution and 24 h of impregnation time are the optimal parameters to prepare efficient carbon effective activated carbon. It was designated as MWLAC (Microwave assisted Zinc chloride activated Leucas aspera carbon). Various adsorption characteristics such as dose of the adsorbent, agitation time, initial Cr(VI) ion concentration, pH of the solution and temperature on adsorption were studied for removal of Cr(VI) ions from aqueous solution by batch mode. Also the equilibrium adsorption was analyzed by the Langmuir, Freundlich, Tempkin and D-R isotherm models. The order of best describing isotherms was given based on R2 value. The pseudo-second-order kinetic model best fitted with the Cr(VI) adsorption data. Thermodynamic parameters were also determined and results suggest that the adsorption process is a spontaneous, endothermic and proceeded with increased randomness.

  5. Equilibrium, Kinetic, and Thermodynamic Studies on the Adsorption of Cadmium from Aqueous Solution by Modified Biomass Ash

    PubMed Central

    Zheng, Xuebo; Cui, Hongbiao; Zhu, Zhenqiu; Liang, Jiani

    2017-01-01

    Natural biomass ash of agricultural residuals was collected from a power plant and modified with hexagonal mesoporous silica and functionalized with 3-aminopropyltriethoxysilane. The physicochemical and morphological properties of the biomass ash were analyzed by ICP-OES, SEM, TEM-EDS, FTIR, and BET analysis. The adsorption behavior of the modified product for Cd2+ in aqueous solution was studied as a function of pH, initial metal concentration, equilibrium time, and temperature. Results showed that the specific surface area of the modified product was 9 times that of the natural biomass ash. The modified biomass ash exhibited high affinity for Cd2+ and its adsorption capacity increased sharply with increasing pH from 4.0 to 6.0. The maximum adsorption capacity was 23.95 mg/g in a pH 5 solution with an initial metal concentration of 50 mg/L and a contact time of 90 min. The adsorption of Cd2+ onto the modified biomass ash was well fitted to the Langmuir model and it followed pseudo-second-order kinetics. Thermodynamic analysis results showed that the adsorption of Cd2+ was spontaneous and endothermic in nature. The results suggest that the modified biomass ash is promising for use as an inexpensive and effective adsorbent for Cd2+ removal from aqueous solution. PMID:28348509

  6. Measurement of surface stay times for physical adsorption of gases. Ph.D. Thesis - Va. Univ.; [using molecular beam time of flight technique

    NASA Technical Reports Server (NTRS)

    Wilmoth, R. G.

    1973-01-01

    A molecular beam time-of-flight technique is studied as a means of determining surface stay times for physical adsorption. The experimental approach consists of pulsing a molecular beam, allowing the pulse to strike an adsorbing surface and detecting the molecular pulse after it has subsequently desorbed. The technique is also found to be useful for general studies of adsorption under nonequilibrium conditions including the study of adsorbate-adsorbate interactions. The shape of the detected pulse is analyzed in detail for a first-order desorption process. For mean stay times, tau, less than the mean molecular transit times involved, the peak of the detected pulse is delayed by an amount approximately equal to tau. For tau much greater than these transit times, the detected pulse should decay as exp(-t/tau). However, for stay times of the order of the transit times, both the molecular speed distributions and the incident pulse duration time must be taken into account.

  7. Aminopyridine modified Spirulina platensis biomass for chromium(VI) adsorption in aqueous solution.

    PubMed

    Bayramoglu, Gulay; Akbulut, Aydin; Arica, M Yakup

    Chemical modification of Spirulina platensis biomass was realized by sequential treatment of algal surface with epichlorohydrin and aminopyridine. Adsorptive properties of Cr(VI) ions on native and aminopyridine modified algal biomass were investigated by varying pH, contact time, ionic strength, initial Cr(VI) concentration, and temperature. FTIR and analytical analysis indicated that carboxyl and amino groups were the major functional groups for Cr(VI) ions adsorption. The optimum adsorption was observed at pH 3.0 for native and modified algal biomasses. The adsorption capacity was found to be 79.6 and 158.7 mg g(-1), for native and modified algal biomasses, respectively. For continuous system studies, the experiments were conducted to study the effect of important design parameters such as flow rate and initial concentration of metal ions, and the maximum sorption capacity was observed at a flow rate of 50 mL h(-1), and Cr(VI) ions concentration 200 mg L(-1) with modified biomass. Experimental data fitted a pseudo-second-order equation. The regeneration performance was observed to be 89.6% and 94.3% for native and modified algal biomass, respectively.

  8. Adsorption of organic stormwater pollutants onto activated carbon from sewage sludge.

    PubMed

    Björklund, Karin; Li, Loretta Y

    2017-07-15

    Adsorption filters have the potential to retain suspended pollutants physically, as well as attracting and chemically attaching dissolved compounds onto the adsorbent. This study investigated the adsorption of eight hydrophobic organic compounds (HOCs) frequently detected in stormwater - including four polycyclic aromatic hydrocarbons (PAHs), two phthalates and two alkylphenols - onto activated carbon produced from domestic sewage sludge. Adsorption was studied using batch tests. Kinetic studies indicated that bulk adsorption of HOCs occurred within 10 min. Sludge-based activated carbon (SBAC) was as efficient as tested commercial carbons for adsorbing HOCs; adsorption capacities ranged from 70 to 2800 μg/g (C initial  = 10-300 μg/L; 15 mg SBAC in 150 mL solution; 24 h contact time) for each HOC. In the batch tests, the adsorption capacity was generally negatively correlated to the compounds' hydrophobicity (log K ow ) and positively associated with decreasing molecule size, suggesting that molecular sieving limited adsorption. However, in repeated adsorption tests, where competition between HOCs was more likely to occur, adsorbed pollutant loads exhibited strong positive correlation with log K ow . Sewage sludge as a carbon source for activated carbon has great potential as a sustainable alternative for sludge waste management practices and production of a high-capacity adsorption material. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Surface chemistry of ferrihydrite: Part 2. Kinetics of arsenate adsorption and coprecipitation

    USGS Publications Warehouse

    Fuller, C.C.; Dadis, J.A.; Waychunas, G.A.

    1993-01-01

    The kinetics of As(V) adsorption by ferrihydrite was investigated in coprecipitation and postsynthesis adsorption experiments conducted in the pH range 7.5-9.0. In coprecipitation experiments, As(V) was present in solution during the hydrolysis and precipitation of iron. In adsorption experiments, a period of rapid (<5 min) As(V) uptake from solution was followed by continued uptake for at least eight days, as As(V) diffused to adsorption sites on ferrihydrite surfaces within aggregates of colloidal particles. The time dependence of As(V) adsorption is well described by a general model for diffusion into a sphere if a subset of surface sites located near the exterior of aggregates is assumed to attain adsorptive equilibrium rapidly. The kinetics of As(V) desorption after an increase in pH were also consistent with diffusion as a rate-limiting process. Aging of pure ferrihydrite prior to As(V) adsorption caused a decrease in adsorption sites on the precipitate owing to crystallite growth. In coprecipitation experiments, the initial As(V) uptake was significantly greater than in post-synthesis adsorption experiments, and the rate of uptake was not diffusion limited because As(V) was coordinated by surface sites before crystallite growth and coagulation processes could proceed. After the initial adsorption, As(V) was slowly released from coprecipitates for at least one month, as crystallite growth caused desorption of As(V). Adsorption densities as high as 0.7 mole As(V) per mole of Fe were measured in coprecipitates, in comparison to 0.25 mole As(V) per mole of Fe in post-synthesis adsorption experiments. Despite the high Concentration of As(V) in the precipitates, EXAFS spectroscopy (Waychunas et al., 1993) showed that neither ferric arsenate nor any other As-bearing surface precipitate or solid solution was formed. The high adsorption densities are possible because the ferrihydrite particles are extremely small, approaching the size of small dioctahedral chains at

  10. Rapid adsorption of 2,4-dichlorophenoxyacetic acid by iron oxide nanoparticles-doped carboxylic ordered mesoporous carbon.

    PubMed

    Tang, Lin; Zhang, Sheng; Zeng, Guang-Ming; Zhang, Yi; Yang, Gui-De; Chen, Jun; Wang, Jing-Jing; Wang, Jia-Jia; Zhou, Yao-Yu; Deng, Yao-Cheng

    2015-05-01

    The ordered mesoporous carbon composite functionalized with carboxylate groups and iron oxide nanoparticles (Fe/OMC) was successfully prepared and used to adsorb 2,4-dichlorophenoxyacetic acid (2,4-D) from wastewater. The resultant adsorbent possessed high degree of order, large specific surface area and pore volume, and good magnetic properties. The increase in initial pollutant concentration and contact time would make the adsorption capacity increase, but the pH and temperature are inversely proportional to 2,4-D uptake. The equilibrium of adsorption was reached within 120 min, and the equilibrated adsorption capacity increased from 99.38 to 310.78 mg/g with the increase of initial concentration of 2,4-D from 100 to 500 mg/L. Notablely, the adsorption capacity reached 97% of the maximum within the first 5 min. The kinetics and isotherm study showed that the pseudo-second-order kinetic and Langmuir isotherm models could well fit the adsorption data. These results indicate that Fe/OMC has a good potential for the rapid adsorption of 2,4-D and prevention of its further diffusion. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Adsorption of Cu2+ to biomass ash and its modified product.

    PubMed

    Xu, Lei; Cui, Hongbiao; Zheng, Xuebo; Liang, Jiani; Xing, Xiangyu; Yao, Lunguang; Chen, Zhaojin; Zhou, Jing

    2017-04-01

    Ash produced by biomass power plants has great potential for the removal of heavy metal ions from aqueous solution. The pollution of toxic heavy metals to water is a worldwide environmental problem. Discharges containing copper, in particular, are strictly controlled because the excessive copper can cause serious harm to the environment and human health. This work aims to investigate the adsorption characteristics of copper ions in aqueous solution by biomass ash and the modified products, and to evaluate their potential application in water pollution control. The biomass ash was modified with a mesoporous siliceous material and functionalized with 3-aminopropyltriethoxysilane. The surface properties of the biomass ash and the new matrix were studied to evaluate their adsorption property for Cu 2+ ions at different pHs, initial metal concentrations and the thermodynamic and kinetic were studied. The chemical and morphological properties of this modified material are analyzed; the specific surface area of the modified biomass ash was nine times that of the initial ash. Both of the two materials showed a strong affinity for Cu 2+ , and the Langmuir model could best represent the adsorption characteristics of Cu 2+ on the two kinds of materials. The adsorption capacity of copper on the material increased with the increase of pH and pH 6 was the optimum pH. Thermodynamic analysis results showed that the adsorption of Cu 2+ was spontaneous and endothermic in nature. The adsorptions of Cu 2+ onto the modified biomass ash followed pseudo-second-order kinetics.

  12. Adsorption kinetics of SO2 on powder activated carbon

    NASA Astrophysics Data System (ADS)

    Li, Bing; Zhang, Qilong; Ma, Chunyuan

    2018-02-01

    The flue gas SO2 adsorption removal by powder activated carbon is investigated based on a fixed bed reactor. The effect of SO2 inlet concentration on SO2 adsorption is investigated and the adsorption kinetics is analyzed. The results indicated that the initial SO2 adsorption rate and the amount of SO2 adsorbed have increased with increased in SO2 inlet concentration. Gas diffusion, surface adsorption and catalytic oxidation reaction are involved in SO2 adsorption on powder activated carbon, which play a different role in different stage. The Bangham kinetics model can be used to predict the kinetics of SO2 adsorption on powder activated carbon.

  13. Adsorption of malachite green from aqueous solution by using novel chitosan ionic liquid beads.

    PubMed

    Naseeruteen, Faizah; Hamid, Nur Shahirah Abdul; Suah, Faiz Bukhari Mohd; Ngah, Wan Saime Wan; Mehamod, Faizatul Shimal

    2018-02-01

    Chitosan ionic liquid beads were prepared from chitosan and 1-butyl-3-methylimidazolium based ionic liquids to remove Malachite Green (MG) from aqueous solutions. Batch adsorption experiments were carried out as a function of initial pH, adsorbent dosage, agitation time and initial MG concentration. The optimum conditions were obtained at pH 4.0, 0.008g of adsorbent dosage and 20min of agitation time were utilized in the kinetic and isotherm studies. Three kinetic models were applied to analyze the kinetic data and pseudo-second order was found to be the best fitted model with R 2 >0.999. In order to determine the adsorption capacity, the sorption data were analyzed using the linear form of Langmuir, Freundlich and Temkin equations. The isotherm was best fitted by Langmuir isotherm model. The maximum adsorption capacity (q max ) obtained from Langmuir isotherm for two chitosan beads 1-butyl-3-methylimidazolium acetate A and 1-butyl-3-methylimidazolium B are 8.07mgg -1 and 0.24mgg -1 respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Adsorption Studies of Gadolinium ion on Graphitic Carbon Nitride

    NASA Astrophysics Data System (ADS)

    Kuila, S. K.; Kundu, T. K.

    2018-03-01

    Bulk graphitic carbon nitride (g-C3N4) is synthesized by thermal decomposition of urea and used as an adsorbent for gadolinium ion (Gd3+) from aqueous solution. Adsorption capacity of g-C3N4 is found to be influenced by initial Gd3+ concentration, solution pH and contact time. Adsorbed Gd3+is separated from g-C3N4 by ultracentrifuge. Initial and Gd ion accumulated g-C3N4 adsorbent are characterized by X-ray diffraction technique (XRD) for phase identification, UV-visible and Fourier transform infrared (FTIR) spectroscopy for adsorption characteristics and optical property, scanning electron microscopy (SEM) for morphological behaviour along with energy dispersive X-ray spectroscopy (EDS) for elemental study. HNO3(0.1M), NaOH (0.1M) and de-ionized water are used for desorption and around 97% quantitative recovery of Gd ion is observed.

  15. Method and apparatus for thermal swing adsorption and thermally-enhanced pressure swing adsorption

    DOEpatents

    Wegeng, Robert S.; Rassat, Scot D.; TeGrotenhuis, Ward E.; Drost, Kevin; Vishwanathan, Vilayanur V.

    2004-06-08

    The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. In another aspect, the apparatus or methods utilize heat exchange channels of varying lengths that have volumes controlled to provide equal heat fluxes. Methods of fuel cell startup are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

  16. Kinetic and thermodynamic studies on the adsorption of anionic surfactant on quaternary ammonium cationic cellulose.

    PubMed

    Zhang, Yuanzhang; Shi, Wenjian; Zhou, Hualan; Fu, Xing; Chen, Xuan

    2010-06-01

    Removal of anionic surfactants from aqueous solutions by adsorption onto quaternary ammonium cationic cellulose (QACC) was investigated. The effects of solution acidity, initial concentration, adsorption time, and temperature on the adsorption of sodium dodecyl-benzene sulfonate (SDBS), sodium lauryl sulfate (SLS), and sodium dodecyl sulfonate (SDS) were studied. The kinetic experimental data fit well with the pseudo-second-order model; the rate constant of the adsorption increased with temperature. The values of apparent activation energy for the adsorption were calculated as ranging from 10.2 to 17.4 kJ/ mol. The adsorption isotherm can be described by the Langmuir isotherm. The values of thermodynamic parameters (deltaH0, deltaS0, and deltaG0) for the adsorption indicated that this process was spontaneous and endothermic. At 318 K, the saturated adsorption capacities of QACC for SDBS, SLS, and SDS were 1.75, 1.53, and 1.39 mmol/g, respectively. The adsorption process was mainly chemisorption and partially physisorption. The results show that QACC is effective for the removal of anionic surfactants.

  17. Comparison of 4-chloro-2-nitrophenol adsorption on single-walled and multi-walled carbon nanotubes

    PubMed Central

    2012-01-01

    The adsorption characteristics of 4-chloro-2-nitrophenol (4C2NP) onto single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) from aqueous solution were investigated with respect to the changes in the contact time, pH of solution, carbon nanotubes dosage and initial 4C2NP concentration. Experimental results showed that the adsorption efficiency of 4C2NP by carbon nanotubes (both of SWCNTs and MWCNTs) increased with increasing the initial 4C2NP concentration. The maximum adsorption took place in the pH range of 2–6. The linear correlation coefficients of different isotherm models were obtained. Results revealed that the Langmuir isotherm fitted the experimental data better than the others and based on the Langmuir model equation, maximum adsorption capacity of 4C2NP onto SWCNTs and MWCNTs were 1.44 and 4.42 mg/g, respectively. The observed changes in the standard Gibbs free energy, standard enthalpy and standard entropy showed that the adsorption of 4C2NP onto SWCNTs and MWCNTs is spontaneous and exothermic in the temperature range of 298–328 K. PMID:23369489

  18. Liquid Phase adsorption kinetics and equilibrium of toluene by novel modified-diatomite.

    PubMed

    Sheshdeh, Reza Khalighi; Abbasizadeh, Saeed; Nikou, Mohammad Reza Khosravi; Badii, Khashayar; Sharafi, Mohammad Sadegh

    2014-01-01

    The adsorption equilibria of toluene from aqueous solutions on natural and modified diatomite were examined at different operation parameters such as pH, contact time, initial toluene concentration was evaluated and optimum experimental conditions were identified. The surface area and morphology of the nanoparticles were characterized by SEM, BET, XRD, FTIR and EDX analysis. It was found that in order to obtain the highest possible removal of toluene, the experiments can be carried out at pH 6, temperature 25°C, an agitation speed of 200 rpm, an initial toluene concentration of 150 mg/L, a centrifugal rate of 4000 rpm, adsorbent dosage = 0.1 g and a process time of 90 min. The results of this work show that the maximum percentage removal of toluene from aqueous solution in the optimum conditions for NONMD was 96.91% (145.36 mg/g). Furthermore, under same conditions, the maximum adsorption of natural diatomite was 71.45% (107.18 mg/g). Both adsorption kinetic and isotherm experiments were carried out. The experimental data showed that the adsorption follows the Langmuir model and Freundlich model on natural and modified diatomite respectively. The kinetics results were found to conform well to pseudo-second order kinetics model with good correlation. Thus, this study demonstrated that the modified diatomite could be used as potential adsorbent for removal of toluene from aqueous solution.

  19. Study on adsorption properties of synthetic materials on marine emulsified oil

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaoyang; Peng, Shitao; Wang, Xiaoli; Zhou, Ran; Luo, Lei

    2018-02-01

    As an effective measure for marine oil spill recovery, adsorption treatment can be adopted in areas where mechanical recovery is not applicable. This experiment is mainly aimed at studying the adsorption properties of synthetic materials on emulsified oil. The emulsified oil was prepared by simulating the emulsification process of marine oil spill via a wave-current flume, and the adsorption weights of synthetic materials on emulsified oil were obtained by performing a field adsorption experiment. Polypropylene, nano-polypropylene and hydrophobic melamine sponge were tested by adsorbing a variety of emulsified oils according to the Adsorption Property Test Method (Version F-726) defined by ASTM. Their adsorption weights on emulsified oil (with initial thickness of 5 mm and water content of 20.86%) are 5.42 g/g, 23.5 g/g and 82.15g/g, respectively, which, compared with that on gear oil in the initial state, are respective decreases of 46.39%, 19.88% and 11.84%, demonstrating obvious decreases in their adsorption performances.

  20. [Active carbon from Thalia dealbata residues: its preparation and adsorption performance to crystal violet].

    PubMed

    Chu, Shu-Yi; Yang, Min; Xiao, Ji-Bo; Zhang, Jun; Zhu, Yan-Ping; Yan, Xiang-Jun; Tian, Guang-Ming

    2013-06-01

    By using phosphoric acid as activation agent, active carbon was prepared from Thalia dealbata residues. The BET specific surface area of the active carbon was 1174.13 m2 x g(-1), micropore area was 426.99 m2 x g(-1), and average pore diameter was 3.23 nm. An investigation was made on the adsorption performances of the active carbon for crystal violet from aqueous solution under various conditions of pH, initial concentration of crystal violet, contact time, and contact temperature. It was shown that the adsorbed amount of crystal violet was less affected by solution pH, and the adsorption process could be divided into two stages, i. e., fast adsorption and slow adsorption, which followed the pseudo-second-order kinetics model. At the temperature 293, 303, and 313 K, the adsorption process was more accordance with Langmuir isotherm model, and the maximum adsorption capacity was 409.83, 425.53, and 438.59 mg x g(-1), respectively. In addition, the adsorption process was spontaneous and endothermic, and the randomness of crystal violet molecules increased.

  1. Kinetic and equilibrium isotherm studies for the adsorptive removal of Brilliant Green dye from aqueous solution by rice husk ash.

    PubMed

    Mane, Venkat S; Deo Mall, Indra; Chandra Srivastava, Vimal

    2007-09-01

    The present study deals with the adsorption of Brilliant Green (BG) on rice husk ash (RHA). RHA is a solid waste obtained from the particulate collection equipment attached to the flue gas lines of rice husk fired boilers. Batch studies were performed to evaluate the influences of various experimental parameters like initial pH (pH0), contact time, adsorbent dose and initial concentration (C0) on the removal of BG. Optimum conditions for BG removal were found to be pH0 approximately 3.0, adsorbent dose approximately 6 g L(-1) of solution and equilibrium time approximately 5 h for the C0 range of 50-300 mg L(-1). Adsorption of BG followed pseudo-second-order kinetics. Intra-particle diffusion does not seem to control the BG removal process. Equilibrium isotherms for the adsorption of BG on RHA were analyzed by Freundlich, Langmuir, Redlich-Peterson (R-P), Dubnin-Radushkevich (D-R), and Temkin isotherm models using a non-linear regression technique. Langmuir and R-P isotherms were found to best represent the data for BG adsorption onto RHA. Adsorption of BG on RHA is favourably influenced by an increase in the temperature of the operation. Values of the change in entropy (DeltaS0) and heat of adsorption (DeltaH0) for BG adsorption on RHA were positive. The high negative value of change in Gibbs free energy (DeltaG0) indicates the feasible and spontaneous adsorption of BG on RHA.

  2. Adsorption characteristics of sol gel-derived zirconia for cesium ions from aqueous solutions.

    PubMed

    Yakout, Sobhy M; Hassan, Hisham S

    2014-07-01

    Zirconia powder was synthesized via a sol gel method and placed in a batch reactor for cesium removal investigation. X-ray analysis and Fourier transform infrared spectroscopy were utilized for the evaluation of the developed adsorbent. The adsorption process has been investigated as a function of pH, contact time and temperature. The adsorption is strongly dependent on the pH of the medium whereby the removal efficiency increases as the pH turns to the alkaline range. The process was initially very fast and the maximum adsorption was attained within 60 min of contact. A pseudo-second-order model and homogeneous particle diffusion model (HPDM) were found to be the best to correlate the diffusion of cesium into the zirconia particles. Furthermore, adsorption thermodynamic parameters, namely the standard enthalpy, entropy, and Gibbs free energy, were calculated. The results indicate that cesium adsorption by zirconia is an endothermic (ΔH>0) process and good affinity of cesium ions towards the sorbent (ΔS>0) was observed.

  3. Adsorptive Removal and Adsorption Kinetics of Fluoroquinolone by Nano-Hydroxyapatite

    PubMed Central

    Chen, Yajun; Lan, Tao; Duan, Lunchao; Wang, Fenghe; Zhao, Bin; Zhang, Shengtian; Wei, Wei

    2015-01-01

    Various kinds of antibiotics, especially fluoroquinolone antibiotics (FQs) have been widely used for the therapy of infectious diseases in human and livestock. For their poorly absorbed by living organisms, large-scale misuse or abuse of FQs will foster drug resistance among pathogenic bacteria, as well as a variety of environmental problems when they were released in the environment. In this work, the adsorption properties of two FQs, namely norfloxacin (NOR) and ciprofloxacin (CIP), by nano-hydroxyapatite (n-HAP) were studied by batch adsorption experiments. The adsorption curves of FQs by n-HAP were simulated by Langmuir and Freundlich isotherms. The results shown that NOR and CIP can be adsorbed effectively by the adsorbent of n-HAP, and the adsorption capacity of FQs increase with increasing dosage of n-HAP. The optimum dosage of n-HAP for FQs removal was 20 g·L-1, in which the removal efficiencies is 51.6% and 47.3%, and an adsorption equilibrium time is 20 min. The maximum removal efficiency occurred when pH is 6 for both FQs. The adsorption isotherm of FQs fits well for both Langmuir and Freundlich equations. The adsorption of both FQs by n-HAP follows second-order kinetics. PMID:26698573

  4. [Adsorption behavior of copper ion and methylene blue on citric acid- esterified wheat straw].

    PubMed

    Sun, Jin; Zhong, Ke-Ding; Feng, Min; Liu, Xing-Yan; Gong, Ren-Min

    2008-03-01

    A cationic adsorbent with carboxyl groups derived from citric acid- esterified wheat straw (EWS) was prepared by the method of solid phase preparation, and a batch experiment was conducted to study the adsorption behaviors of Cu (II) and methylene blue (MB) in aqueous solution on the EWS under conditions of different initial pH, adsorbent dosage, adsorbate concentration, and contact time. The results showed that the maximum adsorption of Cu (II) and MB was obtained when the initial solution pH was > or = 4.0. 96% of Cu (II) in 100 mg x L(-1) Cu solution and 99% of MB in 250 mg x L(-1) dye solution could be removed by > or = 2.0 g x L(-1) of EWS. The adsorption of Cu (II) and MB fitted the Langmuir sorption isothermal model. The maximum removal capacity (Qm) of EWS was 79.37 mg x g(-1) for Cu (II) and 312.50 mg x g(-1) for MB, and the adsorption equilibrium of Cu (II) and MB was reached within 75 min and 5 h, respectively. The adsorption processes of Cu (II) and MB could be described by pseudo-first order and pseudo-second order kinetic functions, respectively.

  5. Combined Homogeneous Surface Diffusion Model - Design of experiments approach to optimize dye adsorption considering both equilibrium and kinetic aspects.

    PubMed

    Muthukkumaran, A; Aravamudan, K

    2017-12-15

    Adsorption, a popular technique for removing azo dyes from aqueous streams, is influenced by several factors such as pH, initial dye concentration, temperature and adsorbent dosage. Any strategy that seeks to identify optimal conditions involving these factors, should take into account both kinetic and equilibrium aspects since they influence rate and extent of removal by adsorption. Hence rigorous kinetics and accurate equilibrium models are required. In this work, the experimental investigations pertaining to adsorption of acid orange 10 dye (AO10) on activated carbon were carried out using Central Composite Design (CCD) strategy. The significant factors that affected adsorption were identified to be solution temperature, solution pH, adsorbent dosage and initial solution concentration. Thermodynamic analysis showed the endothermic nature of the dye adsorption process. The kinetics of adsorption has been rigorously modeled using the Homogeneous Surface Diffusion Model (HSDM) after incorporating the non-linear Freundlich adsorption isotherm. Optimization was performed for kinetic parameters (color removal time and surface diffusion coefficient) as well as the equilibrium affected response viz. percentage removal. Finally, the optimum conditions predicted were experimentally validated. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Optimization of thiamethoxam adsorption parameters using multi-walled carbon nanotubes by means of fractional factorial design.

    PubMed

    Panić, Sanja; Rakić, Dušan; Guzsvány, Valéria; Kiss, Erne; Boskovic, Goran; Kónya, Zoltán; Kukovecz, Ákos

    2015-12-01

    The aim of this work was to evaluate significant factors affecting the thiamethoxam adsorption efficiency using oxidized multi-walled carbon nanotubes (MWCNTs) as adsorbents. Five factors (initial solution concentration of thiamethoxam in water, temperature, solution pH, MWCNTs weight and contact time) were investigated using 2V(5-1) fractional factorial design. The obtained linear model was statistically tested using analysis of variance (ANOVA) and the analysis of residuals was used to investigate the model validity. It was observed that the factors and their second-order interactions affecting the thiamethoxam removal can be divided into three groups: very important, moderately important and insignificant ones. The initial solution concentration was found to be the most influencing parameter on thiamethoxam adsorption from water. Optimization of the factors levels was carried out by minimizing those parameters which are usually critical in real life: the temperature (energy), contact time (money) and weight of MWCNTs (potential health hazard), in order to maximize the adsorbed amount of the pollutant. The results of maximal adsorbed thiamethoxam amount in both real and optimized experiments indicate that among minimized parameters the adsorption time is one that makes the largest difference. The results of this study indicate that fractional factorial design is very useful tool for screening the higher number of parameters and reducing the number of adsorption experiments. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Alginate-immobilized bentonite clay: adsorption efficacy and reusability for Cu(II) removal from aqueous solution.

    PubMed

    Tan, Wei Shang; Ting, Adeline Su Yien

    2014-05-01

    This study evaluated the use of alginate-immobilized bentonite to remove Cu(II) as an alternative to mitigate clogging problems. The adsorption efficacy (under the influence of time, pH and initial Cu(II) concentration) and reusability of immobilized-bentonite (1% w/v bentonite) was tested against plain alginate beads. Results revealed that immobilized bentonite demonstrated significantly higher sorption efficacy compared to plain alginate beads with 114.70 and 94.04 mg Cu(II) adsorbed g(-1) adsorbent, respectively. Both sorbents were comparable in other aspects where sorption equilibrium was achieved within 6 h, with optimum pH between pH 4 and 5 for adsorption, displayed maximum adsorption capacity at initial Cu(II) concentrations of 400 mg l(-1), and demonstrated excellent reusability potential with desorption greater than 90% throughout three consecutive adsorption-desorption cycles. Both sorbents also conformed to Langmuir isotherm and pseudo-second order kinetic model. Immobilized bentonite is therefore recommended for use in water treatments to remove Cu(II) without clogging the system. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Time distribution of adsorption entropy of gases on heterogeneous surfaces by reversed-flow gas chromatography.

    PubMed

    Katsanos, Nicholas A; Kapolos, John; Gavril, Dimitrios; Bakaoukas, Nicholas; Loukopoulos, Vassilios; Koliadima, Athanasia; Karaiskakis, George

    2006-09-15

    The reversed-flow gas chromatography (RF-GC) technique has been applied to measure the adsorption entropy over time, when gaseous pentane is adsorbed on the surface of two solids (gamma-alumina and a silica supported rhodium catalyst) at 393.15 and 413.15K, respectively. Utilizing experimental chromatographic data, this novel methodology also permits the simultaneous measurement of the local adsorption energy, epsilon, local equilibrium adsorbed concentration, c(s)(*), and local adsorption isotherm, theta(p, T, epsilon) in a time resolved way. In contrast with other inverse gas chromatographic methods, which determine the standard entropy at zero surface coverage, the present method operates over a wide range of surface coverage taking into account not only the adsorbate-adsorbent interaction, but also the adsorbate-adsorbate interaction. One of the most interesting observations of the present work is the fact that the interaction of n-pentane is spontaneous on the Rh/SiO(2) catalyst for a very short time interval compared to that on gamma-Al(2)O(3). This can explain the different kinetic behavior of each particular gas-solid system, and it can be attributed to the fact that large amounts of n-C(5)H(12) are present on the active sites of the Rh/SiO(2) catalyst compared to those on gamma-Al(2)O(3), as the local equilibrium adsorbed concentration values, c(s)(*), indicate.

  9. Peroxide-assisted microwave activation of pyrolysis char for adsorption of dyes from wastewater.

    PubMed

    Nair, Vaishakh; Vinu, R

    2016-09-01

    In this study, mesoporous activated biochar with high surface area and controlled pore size was prepared from char obtained as a by-product of pyrolysis of Prosopis juliflora biomass. The activation was carried out by a simple process that involved H2O2 treatment followed by microwave pyrolysis. H2O2 impregnation time and microwave power were optimized to obtain biochar with high specific surface area and high adsorption capacity for commercial dyes such as Remazol Brilliant Blue and Methylene Blue. Adsorption parameters such as initial pH of the dye solution and adsorbent dosage were also optimized. Pore size distribution, surface morphology and elemental composition of activated biochar were thoroughly characterized. H2O2 impregnation time of 24h and microwave power of 600W produced nanostructured biochar with narrow and deep pores of 357m(2)g(-1) specific surface area. Langmuir and Langmuir-Freundlich isotherms described the adsorption equilibrium, while pseudo second order model described the kinetics of adsorption. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Adsorption of n-butane on graphene/Ru(0001)—A molecular beam scattering study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sivapragasam, Nilushni; Nayakasinghe, Mindika T.; Burghaus, Uwe, E-mail: uwe.burghaus@ndsu.edu

    2016-07-15

    Adsorption kinetics/dynamics of n-butane on graphene, physical vapor deposited on Ru(0001) (hereafter G/Ru), and bare Ru(0001) (hereafter Ru) are discussed. The chemical activity of the supported-graphene as well as the support was probed by thermal desorption spectroscopy (adsorption kinetics). In addition and to the best of our knowledge, for the first time, molecular beam scattering data of larger molecules were collected for graphene (probing the adsorption dynamics). Furthermore, samples were inspected by x-ray photoelectron spectroscopy and Auger electron spectroscopy. At the measuring conditions used here, n-butane adsorption kinetics/dynamics are molecular and nonactivated. Binding energies of butane on Ru and G/Rumore » are indistinguishable within experimental uncertainty. Thus, G/Ru is “kinetically transparent.” Initial adsorption probabilities, S{sub 0}, of n-butane decrease with increasing impact energy (0.76–1.72 eV) and are adsorption temperature independent for both Ru and G/Ru, again consistent with molecular adsorption. Also, S{sub 0} of Ru and G/Ru are indistinguishable within experimental uncertainty. Thus, G/Ru is “dynamically transparent.” Coverage dependent adsorption probabilities indicate precursor effects for graphene/Ru.« less

  11. Adsorption behavior and mechanism of Cd(II) on loess soil from China.

    PubMed

    Wang, Yan; Tang, Xiaowu; Chen, Yunmin; Zhan, Liangtong; Li, Zhenze; Tang, Qiang

    2009-12-15

    Cadmium is a toxic heavy metal that has caused serious public health problems. It is necessary to find a cost effective method to deal with wastewater containing Cd(II). Loess soils in China have proven to be a potential adsorbent for Cd(II) removal from wastewater. The adsorption capacity of loess towards Cd(II) has been determined to be about 9.37 mg g(-1). Slurry concentration, initial solution pH, reaction time and temperature have also been found to significantly influence the efficiency of Cd(II) removal. The adsorption isotherms and kinetics of loess soil from China can be best-fit with the Langmuir model and pseudo-second order kinetics model, respectively. The thermodynamic analysis revealed that the adsorption process was spontaneous, endothermic and the system disorder increased with duration. The natural organic matter in loess soil is mainly responsible for Cd(II) removal at pH < 4.2, while clay minerals contribute to a further gradual adsorption process. Chemical precipitation dominates the adsorption stage at pH > 8.97. Further studies using X-ray diffraction, Fourier transform infrared spectra of Cd(II) laden loess soil and Cd(II) species distribution have confirmed the adsorption mechanism.

  12. Adsorption isotherm, kinetic and mechanism of expanded graphite for sulfadiazine antibiotics removal from aqueous solutions.

    PubMed

    Zhang, Ling; Wang, Yong; Jin, SuWan; Lu, QunZan; Ji, Jiang

    2017-10-01

    The adsorption of sulfadiazine from water by expanded graphite (EG), a low cost and environmental-friendly adsorbent, was investigated. Several adsorption parameters (including the initial sulfadiazine concentration, contact time, pH of solution, ionic strength and temperature) were studied. Results of equilibrium experiments indicated that adsorption of sulfadiazine onto EG were better described by the Langmuir and Tempkin models than by the Freundlich model. The maximum adsorption capacity is calculated to be 16.586 mg/g at 298 K. The kinetic data were analyzed by pseudo-first-order, pseudo-second-order and intraparticle models. The results indicated that the adsorption process followed pseudo-second-order kinetics and may be controlled by two steps. Moreover, the pH significantly influenced the adsorption process, with the relatively high adsorption capacity at pH 2-10. The electrostatic and hydrophobic interactions are manifested to be two main mechanisms for sulfadiazine adsorption of EG. Meanwhile, the ionic concentration of Cl - slightly impacted the removal of sulfadiazine. Results of thermodynamics analysis showed spontaneous and exothermic nature of sulfadiazine adsorption on EG. In addition, regeneration experiments imply that the saturated EG could be reused for sulfadiazine removal by immersing sodium hydroxide.

  13. Reactive adsorption of SO2 on activated carbons with deposited iron nanoparticles.

    PubMed

    Arcibar-Orozco, Javier A; Rangel-Mendez, J Rene; Bandosz, Teresa J

    2013-02-15

    The effect of iron particle size anchored on the surface of commercial activated carbon on the removal of SO(2) from a gas phase was studied. Nanosize iron particles were deposited using forced hydrolysis of FeCl(3) with or without H(3)PO(4) as a capping agent. Dynamic adsorption experiments were carried out on either dry or pre-humidified materials and the adsorption capacities were calculated. The surface of the initial and exhausted materials was extensively characterized by microscopic, porosity, thermogravimetric and surface chemistry. The results indicate that the SO(2) adsorption capacity increased two and half times after the prehumidification process owing to the formation of H(2)SO(4) in the porous system. Iron species enhance the SO(2) adsorption capacity only when very small nanoparticles are deposited on the pore walls as a thin layer. Large iron nanoparticles block the ultramicropores decreasing the accessibility of the active sites and consuming oxygen that rest adsorption centers for SO(2) molecules. Iron nanoparticles of about 3-4 nm provide highly dispersed adsorption sites for SO(2) molecules and thus increase the adsorption capacity of about 80%. Fe(2)(SO(4))(3) was detected on the surface of exhausted samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Adsorption kinetics of malachite green onto activated carbon prepared from Tunçbilek lignite.

    PubMed

    Onal, Y; Akmil-Başar, C; Eren, Didem; Sarici-Ozdemir, Cigdem; Depci, Tolga

    2006-02-06

    Adsorbent (T3K618) has been prepared from Tunçbilek lignite by chemical activation with KOH. Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by t-plot based on N2 adsorption isotherm. The N2 adsorption isotherm of malachite green on T3K618 is type I. The BET surface area of the adsorbent which was primarily contributed by micropores was determined 1000 m2/g. T3K618 was used to adsorb malachite green (MG) from an aqueous solution in a batch reactor. The effects of initial dye concentration, agitation time, initial pH and adsorption temperature have been studied. It was also found that the adsorption isotherm followed both Freundlich and Dubinin-Radushkevich models. However, the Freundlich gave a better fit to all adsorption isotherms than the Dubinin-Radushkevich. The kinetics of adsorption of MG has been tested using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. Results show that the adsorption of MG from aqueous solution onto micropores T3K618 proceeds according to the pseudo-second-order model. The intraparticle diffusion of MG molecules within the carbon particles was identified to be the rate-limiting step. The adsorption of the MG was endothermic (DeltaH degrees = 6.55-62.37 kJ/mol) and was accompanied by an increase in entropy (DeltaS degrees = 74-223 J/mol K) and a decrease in mean value of Gibbs energy (DeltaG degrees = -6.48 to -10.32 kJ/mol) in the temperature range of 20-50 degrees C.

  15. Adsorption characteristics of arsenic from micro-polluted water by an innovative coal-based mesoporous activated carbon.

    PubMed

    Li, Wei-Guang; Gong, Xu-Jin; Wang, Ke; Zhang, Xin-Ran; Fan, Wen-Biao

    2014-08-01

    An innovative coal-based mesoporous activated carbon (NCPAC) was prepared by re-agglomeration, oxidation and two-step activation using coal-blending as precursor. Adsorption capacities of As(III) and As(V) ions (<0.5mg/L) onto NCPAC as a function of pH, adsorbent dose, initial arsenic concentrations, contact time, and adsorption isotherms at 7°C was investigated. The innovative methods promoted total pore volume (1.087cm(3)/g), mesoporosity (64.31%), iodine numbers (1104mg/g), methylene blue (251.8mg/g) and ash contents (15.26%). The adsorption capacities of NCPAC for As(III) and As(V) were found to be strongly dependent on pH and contact time. The optimal pH value was 6. The equilibrium time was 60min for adsorption of As(III) and As(V) by NCPAC. The Langmuir model fitted the experimental data well for both As(III) (R(2)=0.9980) and As(V) (R(2)=0.9988). Maximum adsorption capacities of As(III) and As(V) (C0=0.50mg/L) by NCPAC were 1.491 and 1.760mg/g, respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Adsorption of heavy metals on amine-functionalized MCM-48

    NASA Astrophysics Data System (ADS)

    Taba, P.; Budi, P.; Puspitasari, A. Y.

    2017-04-01

    The ordered mesoporous silica with cubic structure, MCM-48 was synthesized by post-synthesis under basic media using colloidal silica, cetyltrimethylammonium bromide, and Triton X-100. The modified material, NH2-MCM-48 was prepared using 3-aminopropyl trimetoxysilane (3-APTMS). X-ray diffraction and FT-IR were used to characterize the samples. The modified material was utilized for adsorption of Cu2+and Mn2+ from aqueous solution. Parameters used for studying the adsorption process were pH, time of contact, and the initial concentrations of Cu2+ and Mn2+ ions. Desorption of ions from the adsorbent was also studied using several desorbing agents. The pseudo-second order was found to be the kinetic order for the metals adsorption. The adsorption of Cu2+ and Mn2+ on NH2-MCM-48 was fixed by the Langmuir model better than the Freundlich model with the capacity of 0.52 and 0.80 mmol g-1 for Cu2+ and Mn2+, respectively. The best desorbing agents for removing the adsorbed Cu2+ and Mn2+ from the adsorbent were 1 M HNO3 and 1 M HC1, respectively.

  17. Adsorption of basic dyes on granular activated carbon and natural zeolite.

    PubMed

    Meshko, V; Markovska, L; Mincheva, M; Rodrigues, A E

    2001-10-01

    The adsorption of basic dyes from aqueous solution onto granular activated carbon and natural zeolite has been studied using an agitated batch adsorber. The influence of agitation, initial dye concentration and adsorbent mass has been studied. The parameters of Langmuir and Freundlich adsorption isotherms have been determined using the adsorption data. Homogeneous diffusion model (solid diffusion) combined with external mass transfer resistance is proposed for the kinetic investigation. The dependence of solid diffusion coefficient on initial concentration and mass adsorbent is represented by the simple empirical equations.

  18. Timing of Initiation of Maintenance Dialysis

    PubMed Central

    Wong, Susan P. Y.; Vig, Elizabeth K.; Taylor, Janelle S.; Burrows, Nilka R.; Liu, Chuan-Fen; Williams, Desmond E.; Hebert, Paul L.; O’Hare, Ann M.

    2016-01-01

    IMPORTANCE There is often considerable uncertainty about the optimal time to initiate maintenance dialysis in individual patients and little medical evidence to guide this decision. OBJECTIVE To gain a better understanding of the factors influencing the timing of initiation of dialysis in clinical practice. DESIGN, SETTING, AND PARTICIPANTS A qualitative analysis was conducted using the electronic medical records from the Department of Veterans Affairs (VA) of a national random sample of 1691 patients for whom the decision to initiate maintenance dialysis occurred in the VA between January 1, 2000, and December 31, 2009. Data analysis took place from June 1 to November 30, 2014. MAIN OUTCOMES AND MEASURES Central themes related to the timing of initiation of dialysis as documented in patients’ electronic medical records. RESULTS Of the 1691 patients, 1264 (74.7%) initiated dialysis as inpatients and 1228 (72.6%) initiated dialysis with a hemodialysis catheter. Cohort members met with a nephrologist during an outpatient clinic visit a median of 3 times (interquartile range, 0–6) in the year prior to initiation of dialysis. The mean (SD) estimated glomerular filtration rate at the time of initiation for cohort members was 10.4 (5.7) mL/min/1.73m2. The timing of initiation of dialysis reflected the complex interplay of at least 3 interrelated and dynamic processes. The first was physician practices, which ranged from practices intended to prepare patients for dialysis to those intended to forestall the need for dialysis by managing the signs and symptoms of uremia with medical interventions. The second process was sources of momentum. Initiation of dialysis was often precipitated by clinical events involving acute illness or medical procedures. In these settings, the imperative to treat often seemed to override patient choice. The third process was patient-physician dynamics. Interactions between patients and physicians were sometimes adversarial, and physician

  19. Assessing changes in the physico-chemical properties and fluoride adsorption capacity of activated alumina under varied conditions

    USGS Publications Warehouse

    Craig, Laura; Stillings, Lisa; Decker, David L.

    2017-01-01

    Adsorption using activated alumina is a simple method for removing fluoride from drinking water, but to be cost effective the adsorption capacity must be high and effective long-term. The intent of this study was to assess changes in its adsorption capacity under varied conditions. This was determined by evaluating the physico-chemical properties, surface charge, and fluoride (F−) adsorption capacity and rate of activated alumina under conditions such as hydration period, particle size, and slow vs. fast titrations. X-ray diffraction and scanning electron microscopy analyses show that the mineralogy of activated alumina transformed to boehmite, then bayerite with hydration period and a corresponding reduction in adsorption capacity was expected; while surface area analyses show no notable changes with hydration period or particle size. The pH dependent surface charge was three times higher using slow potentiometric titrations as compared to fast titrations (due largely to diffusion into pore space), with the surface acidity generally unaffected by hydration period. Results from batch adsorption experiments similarly show no change in fluoride adsorption capacity with hydration period. There was also no notable difference in fluoride adsorption capacity between the particle size ranges of 0.5–1.0 mm and 0.125–0.250 mm, or with hydration period. However, adsorption rate increased dramatically with the finer particle sizes: at an initial F− concentration of 0.53 mmol L−1 (10 mg L−1), 90% was adsorbed in the 0.125–0.250 mm range after 1 h, while the 0.5–1.0 mm range required 24 h to achieve 90% adsorption. Also, the pseudo-second-order adsorption rate constants for the finer vs. larger particle sizes were 3.7 and 0.5 g per mmol F− per min respectively (24 h); and the initial intraparticle diffusion rate of the former was 2.6 times faster than the latter. The results show that adsorption capacity of activated alumina remains consistent and

  20. Surface adsorption of poisonous Pb(II) ions from water using chitosan functionalised magnetic nanoparticles.

    PubMed

    Christopher, Femina Carolin; Anbalagan, Saravanan; Kumar, Ponnusamy Senthil; Pannerselvam, Sundar Rajan; Vaidyanathan, Vinoth Kumar

    2017-06-01

    In this study, chitosan functionalised magnetic nano-particles (CMNP) was synthesised and utilised as an effective adsorbent for the removal of Pb(II) ions from aqueous solution. The experimental studies reveal that adsorbent material has finer adsorption capacity for the removal of heavy metal ions. Parameters affecting the adsorption of Pb(II) ions on CMNP, such as initial Pb(II) ion concentration, contact time, solution pH, adsorbent dosage and temperature were studied. The adsorption equilibrium study showed that present adsorption system followed a Freundlich isotherm model. The experimental kinetic studies on the adsorption of Pb(II) ions exhibited that present adsorption process best obeyed with pseudo-first order kinetics. The maximum monolayer adsorption capacity of CMNP for the removal of Pb(II) ions was found to be 498.6 mg g -1 . The characterisation of present adsorbent material was done by FTIR, energy disperse X-ray analysis and vibrating sample magnetometer studies. Thermodynamic parameters such as Gibbs free energy (Δ G °), enthalpy (Δ H °) and entropy (Δ S °) have declared that the adsorption process was feasible, exothermic and spontaneous in nature. Sticking probability reported that adsorption of Pb(II) ions on CMNP was favourable at lower temperature and sticking capacity of Pb(II) ions was very high.

  1. Uniform Cu{sub 2}Cl(OH){sub 3} hierarchical microspheres: A novel adsorbent for methylene blue adsorptive removal from aqueous solution

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wei, Wei; Gao, Pin; Xie, Jimin, E-mail: xiejm391@sohu.com

    2013-08-15

    Using the solution phase method without any surfactants or templates, the hierarchical of Cu{sub 2}Cl(OH){sub 3} microspheres were synthesized by freeze drying. The size and surface area of the microspheres are ca. 1–2 µm and 76.61 m{sup 2} g{sup −1}, respectively. A possible formation mechanism is presented based on the experimental results. Methylene blue was chosen to investigate the adsorption capacity of the as-prepared adsorbent. The effects of various experimental parameters, such as pH, initial dye concentration, and contact time were investigated. The results showed that the dye removal increased with the increasing in the initial concentration of the dyemore » and also increased in the amount of microspheres used and initial pH. Adsorption data fitted well with the Freundlich adsorption isotherm. The thermodynamic analysis presented the exothermic, spontaneous and more ordered arrangement process. The microspheres could be employed effective for removal of dyes from aqueous solution. - Graphical abstract: The single-crystalline hierarchical Cu{sub 2}Cl(OH){sub 3} spheres can be prepared for the first time by using a template-free process through freeze-drying. Meanwhile, the hierarchical spheres exhibited high adsorption capacity to methylene blue. Display Omitted - Highlights: • Cu{sub 2}Cl(OH){sub 3} microspheres were successfully synthesized through a freeze drying process. • A possible formation mechanism of hierarchical microspheres was presented. • The Cu{sub 2}Cl(OH){sub 3} microspheres have high methylene blue adsorption capacity. • Methylene blue adsorption is a spontaneous and exothermic process. • The adsorption mechanism of microspheres onto dye was proposed in detail.« less

  2. Adsorption of cesium on cement mortar from aqueous solutions.

    PubMed

    Volchek, Konstantin; Miah, Muhammed Yusuf; Kuang, Wenxing; DeMaleki, Zack; Tezel, F Handan

    2011-10-30

    The adsorption of cesium on cement mortar from aqueous solutions was studied in series of bench-scale tests. The effects of cesium concentration, temperature and contact time on process kinetics and equilibrium were evaluated. Experiments were carried out in a range of initial cesium concentrations from 0.0103 to 10.88 mg L(-1) and temperatures from 278 to 313 K using coupons of cement mortar immersed in the solutions. Non-radioactive cesium chloride was used as a surrogate of the radioactive (137)Cs. Solution samples were taken after set periods of time and analyzed by inductively coupled plasma mass spectroscopy. Depending on the initial cesium concentration, its equilibrium concentration in solution ranged from 0.0069 to 8.837 mg L(-1) while the respective surface concentration on coupons varied from 0.0395 to 22.34 μg cm(-2). Equilibrium test results correlated well with the Freundlich isotherm model for the entire test duration. Test results revealed that an increase in temperature resulted in an increase in adsorption rate and a decrease in equilibrium cesium surface concentration. Among several kinetic models considered, the pseudo-second order reaction model was found to be the best to describe the kinetic test results in the studied range of concentrations. The adsorption activation energy determined from Arrhenius equation was found to be approximately 55.9 kJ mol(-1) suggesting that chemisorption was the prevalent mechanism of interaction between cesium ions and cement mortar. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

  3. Kinetics, equilibrium, and thermodynamics investigation on the adsorption of lead(II) by coal-based activated carbon.

    PubMed

    Yi, Zhengji; Yao, Jun; Zhu, Mijia; Chen, Huilun; Wang, Fei; Liu, Xing

    2016-01-01

    The goal of this research is to investigate the feasibility of using activated coal-based activated carbon (CBAC) to adsorb Pb(II) from aqueous solutions through batch tests. Effects of contact time, pH, temperature and initial Pb(II) concentration on the Pb(II) adsorption were examined. The Pb(II) adsorption is strongly dependent on pH, but insensitive to temperature. The best pH for Pb(II) removal is in the range of 5.0-5.5 with more than 90 % of Pb(II) removed. The equilibrium time was found to be 60 min and the adsorption data followed the pseudo-second-order kinetics. Isotherm data followed Langmuir isotherm model with a maximum adsorption capacity of 162.33 mg/g. The adsorption was exothermic and spontaneous in nature. The Fourier transform infrared spectroscopy and scanning electron microscopy analysis suggested that CBAC possessed a porous structure and was rich in carboxyl and hydroxyl groups on its surface, which might play a major role in Pb(II) adsorption. These findings indicated that CBAC has great potential as an alternative adsorbent for Pb(II) removal.

  4. Dynamic surface tension and adsorption mechanism of surfactin biosurfactant at the air-water interface.

    PubMed

    Onaizi, Sagheer A

    2018-03-01

    The dynamic adsorption of the anionic biosurfactant, surfactin, at the air-water interface has been investigated in this work and compared to those of two synthetic surfactants: the anionic sodium dodecylbenzenesulfonate (SDBS) and the nonionic octaethylene glycol monotetradecyl ether (C 14 E 8 ). The results revealed that surfactin adsorption at the air-water interface is purely controlled by diffusion mechanism at the initial stage of the adsorption process (i.e., [Formula: see text]), but shifts towards a mixed diffusion-barrier mechanism when surface tension approaches equilibrium (i.e., [Formula: see text]) due to the development of an energy barrier for adsorption. Such energy barrier has been found to be a function of the surfactin bulk concentration (increases with increasing surfactin concentration) and it is estimated to be in the range of 1.8-9.5 kJ/mol. Interestingly, such a trend (pure diffusion-controlled mechanism at [Formula: see text] and mixed diffusion-barrier mechanism at [Formula: see text]) has been also observed for the nonionic C 14 E 8 surfactant. Unlike the pure diffusion-controlled mechanism of the initial surfactin adsorption, which was the case in the presence and the absence of the sodium ion (Na + ), SDBS showed a mixed diffusion-barrier controlled at both short and long time, with an energy barrier of 3.0-9.0 and 3.8-18.0 kJ/mol, respectively. Such finding highlights the nonionic-like adsorption mechanism of surfactin despite its negative charge.

  5. Chitosan-rectorite nanospheres immobilized on polystyrene fibrous mats via alternate electrospinning/electrospraying techniques for copper ions adsorption

    NASA Astrophysics Data System (ADS)

    Tu, Hu; Huang, Mengtian; Yi, Yang; Li, Zhenshun; Zhan, Yingfei; Chen, Jiajia; Wu, Yang; Shi, Xiaowen; Deng, Hongbing; Du, Yumin

    2017-12-01

    Chitosan (CS), as a kind of well characterized biopolymer, has been used for heavy metal adsorption due to its low cost and high efficacy. However, when used directly, chitosan particles had small surface area and weak mechanical strength which is unfavorable to metal adsorption and reused. Besides, it cannot be easily recycled that may cause a secondary pollution. In this paper, CS and layered silicate rectorite (REC) were fully mixed and the mixtures were subsequently electrosprayed nano-sized spheres, which were immobilized on the surface of electrospun polystyrene (PS) mats for metal adsorption. The morphology analysis taken from SEM confirmed that CS-REC nanospheres were loaded on the surface of PS fibrous mats. Small Angle X-ray diffraction patterns showed that the interlayer distance of REC in composite mats was enlarged by the intercalation of CS chains; such structure meant bigger surface area which was helpful for metal adsorption. The data of contact angle implied that PS mats coated with CS-REC nanospheres exhibited better hydrophilicity than PS mats, which was conductive to adsorption rate. Besides, the copper ions adsorption of composite mats was tested at different conditions including the adsorption time, the initial pH and the initial concentration of copper ion. The results demonstrated that PS mats coated with CS-REC nanospheres had the adsorption capacity up to 134 mg/g. In addition, the addition of REC containing Ca2+ could also improve the metal adsorption because of cation exchange. The desorption assay indicated that PS mats immobilized with CS and CS-REC still kept high adsorption ability which retained 74% and 78% after three adsorption-desorption cycles.

  6. Magnetic graphene oxide for adsorption of organic dyes from aqueous solution

    NASA Astrophysics Data System (ADS)

    Drashya, Lal, Shyam; Hooda, Sunita

    2018-05-01

    Graphene oxide (GO), a 2-D carbon nanomaterial, large surface area, oxygen-containing groups (like: hydroxyl, epoxy and carboxyl) and excellent water dispersibility due to it is good adsorbent dye removal from pollutant water1. But it's difficult to separate GO from water after adsorption. Therefore, Iron oxide was introduced in Graphene oxide by decorating method to make separation more efficient2. We present herein a one step process to prepare Magnetic Graphene oxide (MGO). The Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD) and Raman Spectroscopy characterized the chemical structure of the MGO composite. The adsorption of dyes onto MGO was studied in relation to initial concentration of Dyes, contact time, adsorbent dose, temperature and pH value of solution. We have studied adsorption capacity of different dyes (Methylene blue and crystal violet) by MGO.

  7. Synthesis, characterization, and potential application of Mn2+-intercalated bentonite in fluoride removal: adsorption modeling and mechanism evaluation

    NASA Astrophysics Data System (ADS)

    Mudzielwana, Rabelani; Gitari, Wilson M.; Akinyemi, Segun A.; Msagati, Titus A. M.

    2017-12-01

    The study synthesizes a low-cost adsorbent made from Mn2+-modified bentonite clay for groundwater defluoridation. The clays were characterized using X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and Fourier transform infrared techniques. The fluoride adsorption capacity of the modified clay was evaluated using batch experiments. The adsorption kinetics results showed that the optimum fluoride (F-) uptake was achieved within the 30 min' contact time. The data fitted well to pseudo-second-order of reaction kinetics indicating that adsorption of F- occurred via chemisorption. In addition, the adsorption isotherm data fitted well to Langmuir isotherm model indicating that adsorption occurred on a mono-layered surface. Maximum F- removal of 57% was achieved from groundwater with an initial F- concentration of 5.4 mg L-1 and natural pH of 8.6 using adsorbent dosage of 1 g/100 mL. Fluoride adsorption occurred through ligands and ion exchange mechanisms. The synthesized adsorbent was successfully regenerated for up to five times. The study shows that Mn2+-intercalated bentonite clay has potential for application in defluoridation of groundwater.

  8. Kinetics and Thermodynamics of Reserpine Adsorption onto Strong Acidic Cationic Exchange Fiber

    PubMed Central

    Guo, Zhanjing; Liu, Xiongmin; Huang, Hongmiao

    2015-01-01

    The kinetics and thermodynamics of the adsorption process of reserpine adsorbed onto the strong acidic cationic exchange fiber (SACEF) were studied by batch adsorption experiments. The adsorption capacity strongly depended on pH values, and the optimum reserpine adsorption onto the SACEF occurred at pH = 5 of reserpine solution. With the increase of temperature and initial concentration, the adsorption capacity increased. The equilibrium was attained within 20 mins. The adsorption process could be better described by the pseudo-second-order model and the Freundlich isotherm model. The calculated activation energy Ea was 4.35 kJ/mol. And the thermodynamic parameters were: 4.97<ΔH<7.44 kJ/mol, -15.29<ΔG<-11.87 kJ/mol and 41.97<ΔS<47.35 J/mol·K. The thermodynamic parameters demonstrated that the adsorption was an endothermic, spontaneous and feasible process of physisorption within the temperature range between 283 K and 323 K and the initial concentration range between 100 mg/L and 300 mg/L. All the results showed that the SACEF had a good adsorption performance for the adsorption of reserpine from alcoholic solution. PMID:26422265

  9. Chitosan/nanohydroxyapatite composite based scallop shells as an efficient adsorbent for mercuric ions: Static and dynamic adsorption studies.

    PubMed

    Hassan, Asaad F; Hrdina, Radim

    2018-04-01

    Chitosan/nanohydroxyapatite composites based on scallop shells (CP12, CP14 and CP21) were prepared with different chitosan: nanohydroxyapatite ratios (1:2, 1:4 and 2:1, respectively). Nanohydroxyapatite (P), chitosan(C) and their composites were characterized by means of TGA, XRD, N 2 adsorption/desorption analysis, SEM, Zeta potential and FTIR. The BET surface area ranged between 189 and 512 m 2 /g. Static adsorption of Hg +2 was tested for the effect of adsorbent dosage, pH, time and initial Hg +2 concentrations indicating that maximum static adsorption capacity was confirmed by CP12 (111.6 mg/g). Static adsorption well fitted with Langmuir adsorption isotherm and Pseudo-second order kinetic models. CP12 was selected for dynamic adsorption of Hg +2 considering the effect of bed height, flow rate and the effect of Hg +2 concentrations. Maximum dynamic adsorption capacity was confirmed at bed height of 3 cm, 2.0 mL/min flow rate and 300 mg/L as Hg +2 concentration with breakthrough time (t b ) and exhaustion time (t e ) of 9 and 21 h. Yoon-Nelson and Thomas models best described the experimental Hg +2 breakthrough curve model. After static adsorption, EDTA solution confirmed the maximum desorption efficiency. The validity of CP12 was tested through three cycles of column dynamic adsorption-desorption. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Insight into the adsorption mechanisms of vanadium(V) on a high-efficiency biosorbent (Ti-doped chitosan bead).

    PubMed

    Liu, Xin; Zhang, Lingfan

    2015-08-01

    In this present study, a new chitosan bead modified with titanium ions (TiCB) was prepared and employed for the adsorption of vanadium ions from aqueous solutions. Batch adsorption experiments were performed to research the effect of various factors, including pH, temperature, contact time and initial concentration of vanadium(V) ions. The adsorption of vanadium was followed by the pseudo second-order kinetic and the Langmuir isotherm model, with a remarkable maximum adsorption capacity of 210 mg/g. The analysis of thermodynamic parameters (ΔG°, ΔH° and ΔS°) revealed that the nature of adsorption was feasible, spontaneous (ΔG°<0) and endothermic (ΔH°>0) process. FTIR, EDS, EMI and XPS studies suggested that the mechanisms of adsorption were possibly attributed to electrostatic attraction, ligand-exchange and redox reaction between TiCB and vanadium ions. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Zeolitic imidazolate framework-8 for efficient adsorption and removal of Cr(VI) ions from aqueous solution.

    PubMed

    Niknam Shahrak, Mahdi; Ghahramaninezhad, Mahboube; Eydifarash, Mohsen

    2017-04-01

    Heavy metals are emerging toxic pollutants in which the development of advanced materials for their efficient adsorption and separation is thus of great significance in environmental sciences point of view. In this study, one of the zinc-based zeolitic imidazolate framework materials, known as ZIF-8, has been synthesized and used for chromium(VI) contaminant removal from water for the first time. The as-synthesized ZIF-8 adsorbent was characterized with different methodologies such as powder X-ray diffraction (XRD), thermo-gravimetric analysis, FT-IR, nuclear magnetic resonance spectroscopy, and UV-Vis spectra of solid state. Various factors affecting removal percentage (efficiency) are experimentally investigated including pH of solution, adsorbent dosage, contact time and initial concentration of Cr(VI) to achieve the optimal condition. The obtained results indicate that the ZIF-8 shows good performance for the Cr(VI) removal from aqueous solution so that 60 min mixing of 2 g of ZIF-8 adsorbent with the 2.5 ppm of Cr(VI) solution in a neutral environment will result in the highest separation efficiency around 70%. The time needed to reach the equilibrium (maximum separation efficiency) is only 60 min for a concentration of 5 mg L -1 . Structure stability in the presence of water is also carefully examined by XRD determination of ZIF-8 under different contact times in aqueous solution, which suggests that the structure is going to be destructed after 60 min immersed in solution. Electrostatic interaction of Cr(VI) anions by positively charged ZIF-8 is responsible for Cr(VI) adsorption and separation. Moreover, equilibrium adsorption study reveals that the Cr(VI) removal process using ZIF-8 nicely fits the Langmuir and Toth isotherm models which mean the adsorbent has low heterogeneous surface with different distributions of adsorption energies during Cr(VI) adsorption. Equilibrium adsorption capacity is observed around 0.25 for 20 mg L -1 of initial Cr

  12. Synthesis carbon foams prepared from gelatin (CFG) for cadmium ion adsorption

    NASA Astrophysics Data System (ADS)

    Ulfa, M.; Ulfa, D. K.

    2018-01-01

    In this paper, carbon foam from gelatin (CFG) was synthesized by acid-catalyzed carbonization of gelatin solution on mild condition by the simple method. Gelatin (Ge) were used as sacrificial template and source of carbon. Sulphuric acid was used as acid catalyst. Carbon foam CFG sample were characterized by scanning electron microscope (SEM), nitrogen adsorption desorption and FTIR for knowing textural and structural properties of the sample. Carbon foam CFG sample demonstrated macro pipes-channel like with pore size that varies between 30-40 μ and surface area m 60-100 m2g-1. The carbon foams CFG sample were tested by using adsorption process for obtained their performance for decreasing Cd(II) ions from aqueous solutions. The adsorption capacities for cadmium was 46.7 mg/g obtained by using adsorbent dose 50 mg, initial concentration 50 ppm, contact time, 3 h; room temperature, stirring rate 150 rpm) which reached equilibrium at 55 min. Adsorption process fits using using Lagergren and Ho and McKay equation and measuring data

  13. Heavy metals adsorption by novel EDTA-modified chitosan-silica hybrid materials.

    PubMed

    Repo, Eveliina; Warchoł, Jolanta K; Bhatnagar, Amit; Sillanpää, Mika

    2011-06-01

    Novel adsorbents were synthesized by functionalizing chitosan-silica hybrid materials with (ethylenediaminetetraacetic acid) EDTA ligands. The synthesized adsorbents were found to combine the advantages of both silica gel (high surface area, porosity, rigid structure) and chitosan (surface functionality). The Adsorption potential of hybrid materials was investigated using Co(II), Ni(II), Cd(II), and Pb(II) as target metals by varying experimental conditions such as pH, contact time, and initial metal concentration. The kinetic results revealed that the pore diffusion process played a key role in adsorption kinetics, which might be attributed to the porous structure of synthesized adsorbents. The obtained maximum adsorption capacities of the hybrid materials for the metal ions ranged from 0.25 to 0.63 mmol/g under the studied experimental conditions. The adsorbent with the highest chitosan content showed the best adsorption efficiency. Bi-Langmuir and Sips isotherm model fitting to experimental data suggested the surface heterogeneity of the prepared adsorbents. In multimetal solutions, the hybrid adsorbents showed the highest affinity toward Pb(II). Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Fabrication of the tea saponin functionalized reduced graphene oxide for fast adsorptive removal of Cd(II) from water

    NASA Astrophysics Data System (ADS)

    Li, Zhigang; Liu, Zhifeng; Wu, Zhibin; Zeng, Guangming; Shao, Binbin; Liu, Yujie; Jiang, Yilin; Zhong, Hua; Liu, Yang

    2018-05-01

    A novel graphene-based material of tea saponin functionalized reduced graphene oxide (TS-RGO) was synthesized via a facil thermal method, and it was characterized as the absorbent for Cd(II) removal from aqueous solutions. The factors on adsorption process including solution pH, contact time, initial concentration of Cd(II) and background electrolyte cations were studied to optimize the conditions for maximum adsorption at room temperature. The results indicated that Cd(II) adsorption was strongly dependent on pH and could be strongly affected by background electrolytes and ionic strength. The optimal pH and required equilibrium time was 6.0 and 10 min, respectively. The Cd(II) removal decreased with the presence of background electrolyte cations (Na+ < Ca2+ < Al3+). The adsorption kinetics of Cd(II) followed well with the pseudo-second-order model. The adsorption isotherm fitted well to the Langmuir model, indicating that the adsorption was a monolayer adsorption process occurred on the homogeneous surfaces of TS-RGO. The maximum monolayer adsorption capacity was 127 mg/g at 313 K and pH 6.0. Therefore, the TS-RGO was considered to be a cost-effective and promising material for the removal of Cd(II) from wastewater.

  15. Irreversible adsorption of particles on heterogeneous surfaces.

    PubMed

    Adamczyk, Zbigniew; Jaszczółt, Katarzyna; Michna, Aneta; Siwek, Barbara; Szyk-Warszyńska, Lilianna; Zembala, Maria

    2005-12-30

    Methods of theoretical and experimental evaluation of irreversible adsorption of particles, e.g., colloids and globular proteins at heterogeneous surfaces were reviewed. The theoretical models were based on the generalized random sequential adsorption (RSA) approach. Within the scope of these models, localized adsorption of particles occurring as a result of short-ranged attractive interactions with discrete adsorption sites was analyzed. Monte-Carlo type simulations performed according to this model enabled one to determine the initial flux, adsorption kinetics, jamming coverage and the structure of the particle monolayer as a function of the site coverage and the particle/site size ratio, denoted by lambda. It was revealed that the initial flux increased significantly with the site coverage theta(s) and the lambda parameter. This behavior was quantitatively interpreted in terms of the scaled particle theory. It also was demonstrated that particle adsorption kinetics and the jamming coverage increased significantly, at fixed site coverage, when the lambda parameter increased. Practically, for alpha = lambda2theta(s) > 1 the jamming coverage at the heterogeneous surfaces attained the value pertinent to continuous surfaces. The results obtained prove unequivocally that spherically shaped sites were more efficient in binding particles in comparison with disk-shaped sites. It also was predicted that for particle size ratio lambda < 4 the site multiplicity effect plays a dominant role, affecting significantly the structure of particle monolayers and the jamming coverage. Experimental results validating main aspects of these theoretical predictions also have been reviewed. These results were derived by using monodisperse latex particles adsorbing on substrates produced by covering uniform surface by adsorption sites of a desired size, coverage and surface charge. Particle deposition occurred under diffusion-controlled transport conditions and their coverage was

  16. Protein Adsorption in Three Dimensions

    PubMed Central

    Vogler, Erwin A.

    2011-01-01

    Recent experimental and theoretical work clarifying the physical chemistry of blood-protein adsorption from aqueous-buffer solution to various kinds of surfaces is reviewed and interpreted within the context of biomaterial applications, especially toward development of cardiovascular biomaterials. The importance of this subject in biomaterials surface science is emphasized by reducing the “protein-adsorption problem” to three core questions that require quantitative answer. An overview of the protein-adsorption literature identifies some of the sources of inconsistency among many investigators participating in more than five decades of focused research. A tutorial on the fundamental biophysical chemistry of protein adsorption sets the stage for a detailed discussion of the kinetics and thermodynamics of protein adsorption, including adsorption competition between two proteins for the same adsorbent immersed in a binary-protein mixture. Both kinetics and steady-state adsorption can be rationalized using a single interpretive paradigm asserting that protein molecules partition from solution into a three-dimensional (3D) interphase separating bulk solution from the physical-adsorbent surface. Adsorbed protein collects in one-or-more adsorbed layers, depending on protein size, solution concentration, and adsorbent surface energy (water wettability). The adsorption process begins with the hydration of an adsorbent surface brought into contact with an aqueous-protein solution. Surface hydration reactions instantaneously form a thin, pseudo-2D interface between the adsorbent and protein solution. Protein molecules rapidly diffuse into this newly-formed interface, creating a truly 3D interphase that inflates with arriving proteins and fills to capacity within milliseconds at mg/mL bulk-solution concentrations CB. This inflated interphase subsequently undergoes time-dependent (minutes-to-hours) decrease in volume VI by expulsion of either-or-both interphase water and

  17. Adsorption of Copper Ion using Acrylic Acid-g-Polyaniline in Aqueous Solution

    NASA Astrophysics Data System (ADS)

    Kamarudin, Sabariah; Mohammad, Masita

    2018-04-01

    A conductive polymer, polyaniline (PANI) has unique electrical behaviour, stable in the environment, easy synthesis and have wide application in various fields. Modification of PANI in order to improve its adsorption capacity has been done. In this study, the polyaniline-grafted acrylic acid has been prepared and followed by adsorption of copper ion in aqueous solution. Acrylic acid, PANI and acrylic acid-g-polyaniline (Aag-PANI) were characterized by FTIR and SEM to determine its characteristic. The adsorption capacity was investigated to study the removal capacity of Cu ion from aqueous solution. Two parameters were selected which are pH (2, 4 and 6) and initial metal ion concentration (50 mg/L, 100 mg/L and 200 mg/L). The maximum adsorption capacity for PANI and Aag-PANI are 1.7 mg/g and 64.6 mg/g, respectively, at an initial concentration of 100 mg/L. The Langmuir adsorption isotherm model and Freundlich adsorption isotherm model have been used and showed that it is heterolayer adsorption by follows the Freundlich isotherm model.

  18. The removal of fluoride from aqueous solution by a lateritic soil adsorption: Kinetic and equilibrium studies.

    PubMed

    Iriel, Analia; Bruneel, Stijn P; Schenone, Nahuel; Cirelli, Alicia Fernández

    2018-03-01

    The use of natural sorbents to remove fluoride from drinking water is a promising alternative because of its low-cost and easy implementation. In this article, fluoride adsorption on a latosol soil from Misiones province (Argentina) was studied regarding kinetic and equilibrium aspects. Experiments were conducted in batch at room temperature under controlled conditions of pH 4-8) and ionic strength (1-10mM KNO 3 ). Experimental data indicated that adsorption processes followed a PSO kinetic where initial rates have showed to be influenced by pH solution. The necessary time to reach an equilibrium state had resulted approximately 30min. Equilibrium adsorption studies were performed at pH 8 which is similar to the natural groundwater. For that, fluoride adsorption data were successfully adjusted to Dubinin-Ataskhov model determining that the fluoride adsorption onto soil particles mainly followed a physical mechanism with a removal capacity of 0.48mgg -1 . Finally, a natural groundwater was tested with laterite obtaining a reduction close to 30% from initial concentration and without changing significantly the physicochemical properties of the natural water. Therefore, it was concluded that the use of lateritic soils for fluoride removal is very promising on a domestic scale. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Individual and competitive adsorption of phenol and nickel onto multiwalled carbon nanotubes

    PubMed Central

    Abdel-Ghani, Nour T.; El-Chaghaby, Ghadir A.; Helal, Farag S.

    2014-01-01

    Individual and competitive adsorption studies were carried out to investigate the removal of phenol and nickel ions by adsorption onto multiwalled carbon nanotubes (MWCNTs). The carbon nanotubes were characterized by different techniques such as X-ray diffraction, scanning electron microscopy, thermal analysis and Fourier transformation infrared spectroscopy. The different experimental conditions affecting the adsorption process were investigated. Kinetics and equilibrium models were tested for fitting the adsorption experimental data. The characterization experimental results proved that the studied adsorbent possess different surface functional groups as well as typical morphological features. The batch experiments revealed that 300 min of contact time was enough to achieve equilibrium for the adsorption of both phenol and nickel at an initial adsorbate concentration of 25 mg/l, an adsorbent dosage of 5 g/l, and a solution pH of 7. The adsorption of phenol and nickel by MWCNTs followed the pseudo-second order kinetic model and the intraparticle diffusion model was quite good in describing the adsorption mechanism. The Langmuir equilibrium model fitted well the experimental data indicating the homogeneity of the adsorbent surface sites. The maximum Langmuir adsorption capacities were found to be 32.23 and 6.09 mg/g, for phenol and Ni ions, respectively. The removal efficiency of MWCNTs for nickel ions or phenol in real wastewater samples at the optimum conditions reached up to 60% and 70%, respectively. PMID:26257938

  20. GIS-NaP1 zeolite microspheres as potential water adsorption material: Influence of initial silica concentration on adsorptive and physical/topological properties

    PubMed Central

    Sharma, Pankaj; Song, Ju-Sub; Han, Moon Hee; Cho, Churl-Hee

    2016-01-01

    GIS-NaP1 zeolite samples were synthesized using seven different Si/Al ratios (5–11) of the hydrothermal reaction mixtures having chemical composition Al2O3:xSiO2:14Na2O:840H2O to study the impact of Si/Al molar ratio on the water vapour adsorption potential, phase purity, morphology and crystal size of as-synthesized GIS-NaP1 zeolite crystals. The X-ray diffraction (XRD) observations reveal that Si/Al ratio does not affect the phase purity of GIS-NaP1 zeolite samples as high purity GIS-NaP1 zeolite crystals were obtained from all Si/Al ratios. Contrary, Si/Al ratios have remarkable effect on the morphology, crystal size and porosity of GIS-NaP1 zeolite microspheres. Transmission electron microscopy (TEM) evaluations of individual GIS-NaP1 zeolite microsphere demonstrate the characteristic changes in the packaging/arrangement, shape and size of primary nano crystallites. Textural characterisation using water vapour adsorption/desorption, and nitrogen adsorption/desorption data of as-synthesized GIS-NaP1 zeolite predicts the existence of mix-pores i.e., microporous as well as mesoporous character. High water storage capacity 1727.5 cm3 g−1 (138.9 wt.%) has been found for as-synthesized GIS-NaP1 zeolite microsphere samples during water vapour adsorption studies. Further, the total water adsorption capacity values for P6 (1299.4 mg g−1) and P7 (1388.8 mg g−1) samples reveal that these two particular samples can absorb even more water than their own weights. PMID:26964638

  1. GIS-NaP1 zeolite microspheres as potential water adsorption material: Influence of initial silica concentration on adsorptive and physical/topological properties.

    PubMed

    Sharma, Pankaj; Song, Ju-Sub; Han, Moon Hee; Cho, Churl-Hee

    2016-03-11

    GIS-NaP1 zeolite samples were synthesized using seven different Si/Al ratios (5-11) of the hydrothermal reaction mixtures having chemical composition Al2O3:xSiO2:14Na2O:840H2O to study the impact of Si/Al molar ratio on the water vapour adsorption potential, phase purity, morphology and crystal size of as-synthesized GIS-NaP1 zeolite crystals. The X-ray diffraction (XRD) observations reveal that Si/Al ratio does not affect the phase purity of GIS-NaP1 zeolite samples as high purity GIS-NaP1 zeolite crystals were obtained from all Si/Al ratios. Contrary, Si/Al ratios have remarkable effect on the morphology, crystal size and porosity of GIS-NaP1 zeolite microspheres. Transmission electron microscopy (TEM) evaluations of individual GIS-NaP1 zeolite microsphere demonstrate the characteristic changes in the packaging/arrangement, shape and size of primary nano crystallites. Textural characterisation using water vapour adsorption/desorption, and nitrogen adsorption/desorption data of as-synthesized GIS-NaP1 zeolite predicts the existence of mix-pores i.e., microporous as well as mesoporous character. High water storage capacity 1727.5 cm(3) g(-1) (138.9 wt.%) has been found for as-synthesized GIS-NaP1 zeolite microsphere samples during water vapour adsorption studies. Further, the total water adsorption capacity values for P6 (1299.4 mg g(-1)) and P7 (1388.8 mg g(-1)) samples reveal that these two particular samples can absorb even more water than their own weights.

  2. Adsorption of Hg2+, Cu2+ and Zn2+ ions from aqueous solution using formaldehyde cross-linked modified chitosan-thioglyceraldehyde Schiff's base.

    PubMed

    Monier, M

    2012-04-01

    A chitosan-thioglyceraldehyde Schiff's base cross-linked magnetic resin (CSTG) was prepared and characterized using various instrumental methods. Then, the prepared resin was used for comparative studies on the removal of toxic metal ions like: Hg(2+), Cu(2+) and Zn(2+) from aqueous solutions. The effects of the initial pH value of the solution, contact time, the initial metal ion concentration and temperature on the adsorption capacity of the composite were investigated. The kinetics data were analyzed by pseudo-first order and pseudo-second order equations. The adsorption kinetics was well described by the pseudo-second order equation, and the adsorption isotherms were better fitted by the Langmuir equation. The maximum theoretical adsorption capacities of the CSTG resin for Hg(2+), Cu(2+) and Zn(2+) were found to be 98±2, 76±1 and 52±1 mg g(-1), respectively. The negative values of Gibbs free energy of adsorption (ΔG(ads°) indicated the spontaneity of the adsorption of all metal ions on the novel resin. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Adsorption of pharmaceuticals onto trimethylsilylated mesoporous SBA-15.

    PubMed

    Bui, Tung Xuan; Pham, Viet Hung; Le, Son Thanh; Choi, Heechul

    2013-06-15

    The adsorption of a complex mixture of 12 selected pharmaceuticals to trimethylsilylated mesoporous SBA-15 (TMS-SBA-15) has been investigated by batch adsorption experiments. The adsorption of pharmaceuticals to TMS-SBA-15 was highly dependent on the solution pH and pharmaceutical properties (i.e., hydrophobicity (logKow) and acidity (pKa)). Good log-log linear relationships between the adsorption (Kd) and pH-dependent octanol-water coefficients (Kow(pH)) were then established among the neutral, anionic, and cationic compounds, suggesting hydrophobic interaction as a primary driving force in the adsorption. In addition, the neutral species of each compound accounted for a major contribution to the overall compound adsorption onto TMS-SBA-15. The adsorption kinetics of pharmaceuticals was evaluated by the nonlinear first-order and pseudo-second-order models. The first-order model gave a better fit for five pharmaceuticals with lower adsorption capacity, whereas the pseudo-second-order model fitted better for seven pharmaceuticals having higher adsorption capacity. In the same group of properties, pharmaceuticals having higher adsorption capacity exhibited faster adsorption rates. The rate-limiting steps for adsorption of pharmaceuticals onto TMS-SBA-15 are boundary layer diffusion and intraparticle diffusion including diffusion in mesopores and micropores. In addition, the adsorption of pharmaceuticals to TMS-SBA-15 was not influenced by the change of initial pharmaceutical concentration (10-100μgL(-1)) and the presence of natural organic matter. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Mechanical and dye adsorption properties of graphene oxide/chitosan composite fibers prepared by wet spinning.

    PubMed

    Li, Yanhui; Sun, Jiankun; Du, Qiuju; Zhang, Luhui; Yang, Xiaoxia; Wu, Shaoling; Xia, Yanzhi; Wang, Zonghua; Xia, Linhua; Cao, Anyuan

    2014-02-15

    Graphene oxide/chitosan composite fibers were prepared by a wet spinning method, and their mechanical properties were investigated. Experimental results showed that the introduction of graphene oxide at 4 wt% loading can improve the tensile strengths of chitosan fibers. Batch adsorption experiments were carried out to study the effect of various parameters, such as the initial pH value, adsorbent dosage, contact time and temperature on adsorption of fuchsin acid dye. The Langmuir model was used to fit the experimental data of adsorption isotherm, and kinetic studies showed that the adsorption data followed the pseudo-second order model. Thermodynamic studies indicated that the adsorption of fuchsin acid dye on graphene oxide/chitosan fibers was a spontaneous and exothermic process. Our results indicate that the graphene oxide/chitosan fibers have excellent mechanical properties and can serve as a promising adsorbent for the removal of dyes from aqueous solutions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Adsorption energies and prefactor determination for CH3OH adsorption on graphite.

    PubMed

    Doronin, M; Bertin, M; Michaut, X; Philippe, L; Fillion, J-H

    2015-08-28

    In this paper, we have studied adsorption and thermal desorption of methanol CH3OH on graphite surface, with the specific aim to derive from experimental data quantitative parameters that govern the desorption, namely, adsorption energy Eads and prefactor ν of the Polanyi-Wigner law. In low coverage regime, these two values are interconnected and usually the experiments can be reproduced with any couple (Eads, ν), which makes intercomparison between studies difficult since the results depend on the extraction method. Here, we use a method for determining independently the average adsorption energy and a prefactor value that works over a large range of incident methanol coverage, from a limited set of desorption curves performed at different heating rates. In the low coverage regime the procedure is based on a first order kinetic law, and considers an adsorption energy distribution which is not expected to vary with the applied heating rate. In the case of CH3OH multilayers, Eads is determined as 430 meV with a prefactor of 5 × 10(14) s(-1). For CH3OH submonolayers on graphite, adsorption energy of 470 ± 30 meV and a prefactor of (8 ± 3) × 10(16) s(-1) have been found. These last values, which do not change between 0.09 ML and 1 ML initial coverage, suggest that the methanol molecules form island-like structure on the graphite even at low coverage.

  6. UV-induced photocatalytic degradation of aqueous acetaminophen: the role of adsorption and reaction kinetics.

    PubMed

    Basha, Shaik; Keane, David; Nolan, Kieran; Oelgemöller, Michael; Lawler, Jenny; Tobin, John M; Morrissey, Anne

    2015-02-01

    Nanostructured titania supported on activated carbon (AC), termed as integrated photocatalytic adsorbents (IPCAs), were prepared by ultrasonication and investigated for the photocatalytic degradation of acetaminophen (AMP), a common analgesic and antipyretic drug. The IPCAs showed high affinity towards AMP (in dark adsorption studies), with the amount adsorbed proportional to the TiO2 content; the highest adsorption was at 10 wt% TiO2. Equilibrium isotherm studies showed that the adsorption followed the Langmuir model, indicating the dependence of the reaction on an initial adsorption step, with maximum adsorption capacity of 28.4 mg/g for 10 % TiO2 IPCA. The effects of initial pH, catalyst amount and initial AMP concentration on the photocatalytic degradation rates were studied. Generally, the AMP photodegradation activity of the IPCAs was better than that of bare TiO2. Kinetic studies on the photocatalytic degradation of AMP under UV suggest that the degradation followed Langmuir-Hinshelwood (L-H) kinetics, with an adsorption rate constant (K) that was considerably higher than the photocatalytic rate constant (k r), indicating that the photocatalysis of AMP is the rate-determining step during the adsorption/photocatalysis process.

  7. Adsorption and catalytic properties of sulfated aluminum oxide modified with cobalt ions

    NASA Astrophysics Data System (ADS)

    Lanin, S. N.; Bannykh, A. A.; Vlasenko, E. V.; Krotova, I. N.; Obrezkov, O. N.; Shilina, M. I.

    2017-01-01

    The adsorption properties of sulfated aluminum oxide (9% SO 4 2- /γ-Al2O3) and a cobalt-containing composite (0.5%Co/SO 4 2- /γ-Al2O3) based on it are studied via dynamic sorption. The adsorption isotherms of such test adsorbates as n-hydrocarbons (C6-C8), benzene, ethylbenzene, chloroform, and diethyl ether are measured, and their isosteric heats of adsorption are calculated. It is shown that the surface sulfation of aluminum oxide substantially improves its electron-accepting properties, and so the catalytic activity of SO 4 2- /γ-Al2O3 in the liquid-phase alkylation of benzene with octene-1 at temperatures of 25-120°C is one order of magnitude higher than for the initial aluminum oxide. It is established that additional modification of sulfated aluminum oxide with cobalt ions increases the activity of this catalyst by 2-4 times. It is shown that adsorption sites capable of strong specific adsorption with both donating (aromatics, diethyl ether chemosorption) and accepting molecules (chloroform) form on the surface of sulfated γ-Al2O3 promoted by cobalt salt.

  8. Real-Time Monitoring of Azo Dye Interfacial Adsorption at Silica-Water Interface by Total Internal Reflection-Induced Surface Evanescent Wave.

    PubMed

    Xiong, Yan; Wang, Qing; Duan, Ming; Tan, Jun; Fang, Shenwen; Wu, Jiayi

    2018-06-19

    An interface research method based on total internal reflection induced evanescent wave (TIR-EW) is developed to monitor the adsorption behavior of azo dye at the silica-water interface. The monitoring system is constructed by employing silica optical fiber (SOF) as both charged substrate for dye adsorption and light transmission waveguide for evanescent wave production. According to the change of evanescent wave intensity and followed by Beer's law, the methylene blue (MB) adsorption behavior can be real-time monitored at the silica-water interface. Langmuir adsorption model and pseudo-first-order model are applied to obtain the related thermodynamic and kinetic data. The adsorption equilibrium constant ( K ads ) and adsorption free energy (Δ G) of MB at the silica-water interface are determined to be (3.3 ± 0.5) × 10 4 M -1 and -25.7 ± 1.7 kJ mol -1 . Meanwhile, this method is highlighted to isolate elementary processes of adsorption and desorption under steady-state conditions, and gives adsorption rate constant ( k a ) and desorption rate constant ( k d ) of 8585 ± 19.8 min -1 and 0.26 ± 0.0006 min -1 for 15 r/min flow rate. The surface interaction process is revealed and adsorption mechanism is proposed, indicating MB first adsorbed on Si-O - sites through electrostatic attraction and then on Si-OH sites through hydrogen bond with increasing MB concentrations. Our findings from this study provided molecular-level interpretation of azo dye adsorption at silica-water interface, and the results provide important insight into how MB adsorption can be controlled at the interface.

  9. Adsorption of Pb(II) from fish sauce using carboxylated cellulose nanocrystal: Isotherm, kinetics, and thermodynamic studies.

    PubMed

    Wang, Nan; Jin, Ru-Na; Omer, A M; Ouyang, Xiao-Kun

    2017-09-01

    In the present study, a new adsorbent based on carboxylated cellulose nanocrystal (CCN) was developed for the adsorption of Pb(II) from fish sauce. The prepared adsorbent material was characterized by zeta potential, FT-IR, XRD, and XPS tools. The changes in the morphological structure of the developed CCN surface were evidenced by SEM and TEM. The favorable adsorption conditions were selected by studying the contact time, initial concentration, temperature, and concentration of the used glutamic acid and NaCl. The results indicated that the Langmuir isotherm model agrees very well with experimental adsorption data (R 2 =0.9962) with a maximum adsorption capacity 232.56mg/g of Pb(II) at 293.2K. Additionally, data of the adsorption kinetics follow the pseudo-second-order kinetics (R 2 >0.9990). On the other hand, the thermodynamics studies show that the adsorption process is spontaneous and endothermic. Furthermore, the developed CCN could be regenerated using acid treatment with a good reusability for Pb(II) adsorption. The results clearly indicated that the synthesized CCN could be effectively applied as a new material for Pb(II) adsorption from fish sauce solutions. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Adsorption of leather dye onto activated carbon prepared from bottle gourd: equilibrium, kinetic and mechanism studies.

    PubMed

    Foletto, Edson Luiz; Weber, Caroline Trevisan; Paz, Diego Silva; Mazutti, Marcio Antonio; Meili, Lucas; Bassaco, Mariana Moro; Collazzo, Gabriela Carvalho

    2013-01-01

    Activated carbon prepared from bottle gourd has been used as adsorbent for removal of leather dye (Direct Black 38) from aqueous solution. The activated carbon obtained showed a mesoporous texture, with surface area of 556.16 m(2) g(-1), and a surface free of organic functional groups. The initial dye concentration, contact time and pH significantly influenced the adsorption capacity. In the acid region (pH 2.5) the adsorption of dye was more favorable. The adsorption equilibrium was attained after 60 min. Equilibrium data were analyzed by the Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models. The equilibrium data were best described by the Langmuir isotherm, with maximum adsorption capacity of 94.9 mg g(-1). Adsorption kinetic data were fitted using the pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models. The adsorption kinetic was best described by the second-order kinetic equation. The adsorption process was controlled by both external mass transfer and intraparticle diffusion. Activated carbon prepared from bottle gourd was shown to be a promising material for adsorption of Direct Black 38 from aqueous solution.

  11. Highly efficient indoor air purification using adsorption-enhanced-photocatalysis-based microporous TiO2 at short residence time.

    PubMed

    Lv, Jinze; Zhu, Lizhong

    2013-01-01

    A short residence time is a key design parameter for the removal of organic pollutants in catalyst-based indoor air purification systems. In this study, we synthesized a series of TiO2 with different micropore volumes and studied their removal efficiency of indoor carbonyl pollutants at a short residence time. Our results indicated that the superior adsorption capability of TiO2 with micropores improved its performance in the photocatalytic degradation of cyclohexanone, while the photocatalytic removal of the pollutant successfully kept porous TiO2 from becoming saturated. When treated with 1 mg m(-3) cyclohexanone at a relatively humidity of 18%, the adsorption amount on microporous TiO2 was 5.4-7.9 times higher than that on P25. Removal efficiency via photocatalysis followed'the same order as the adsorption amount: TiO2-5 > TiO2-20 > TiO2-60 > TiO2-180 > P25. The advantage of microporous TiO2 over P25 became more pronounced when the residence time declined from 0.072 to 0.036 s. Moreover, as the concentration of cyclohexanone deceased from 1000 ppb to 500 ppb, removal efficiency by microporous TiO2 increased more rapidly than P25.

  12. Ozone adsorption on carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Chassard, Guillaume; Gosselin, Sylvie; Visez, Nicolas; Petitprez, Denis

    2014-05-01

    Carbonaceous particles produced by incomplete combustion or thermal decomposition of hydrocarbons are ubiquitous in the atmosphere. On these particles are adsorbed hundreds of chemical species. Those of great concern to health are polycyclic aromatic hydrocarbons (PAHs). During atmospheric transport, particulate PAHs react with gaseous oxidants. The induced chemical transformations may change toxicity and hygroscopicity of these potentially inhalable particles. The interaction between ozone and carbon particles has been extensively investigated in literature. However ozone adsorption and surface reaction mechanisms are still ambiguous. Some studies described a fast catalytic decomposition of ozone initiated by an atomic oxygen chemisorption followed by a molecular oxygen release [1-3]. Others suggested a reversible ozone adsorption according to Langmuir-type behaviour [4,5]. The aim of this present study is a better understanding of ozone interaction with carbon surfaces. An aerosol of carbon nanoparticles was generated by flowing synthetic air in a glass tube containing pure carbon (primary particles < 50 nm), under magnetic stirring. The aerosol was then mixed with ozone in an aerosol flow tube. Ozone uptake experiments were performed with different particles concentrations with a fixed ozone concentration. The influence of several factors on kinetics was examined: initial ozone concentration, particle size (50 nm ≤ Dp ≤ 200 nm) and competitive adsorption (with probe molecule and water). The effect of initial ozone concentration was first studied. Accordingly to literature, it has been observed that the number of gas-phase ozone molecules lost per unit particle surface area tends towards a plateau for high ozone concentration suggesting a reversible ozone adsorption according to a Langmuir mechanism. We calculated the initial reaction probability between O3 and carbon particles.An initial uptake coefficient of 1.10-4 was obtained. Similar experiments were

  13. Adsorption of anionic surfactants from aqueous solution by high content of primary amino crosslinked chitosan microspheres.

    PubMed

    Zhang, Caihong; Wen, Haifeng; Huang, Yingying; Shi, Wenjian

    2017-04-01

    High content of primary amino crosslinked chitosan microspheres (ACCMs) were synthesized and characterized with IR, XRD and SEM technologies. Subsequently, ACCMs were adopted to adsorb three common anionic surfactants from aqueous solution: sodium dodecyl benzene sulfonate (SDBS), sodium lauryl sulfate (SLS), and sodium dodecyl sulfonate (SDS). The adsorption performances were evaluated based on different variables such as the pH, contact time, temperature and initial concentration of the anionic surfactants. Moreover, the adsorption were investigated with kinetic models, equilibrium isotherms and thermodynamic models. The experimental results indicated that the adsorption processes were fitted very well with a pseudo-second-order model. The adsorption isotherms could be better described by Langmuir model rather than Freundlich model. The adsorption of SDBS was a spontaneous, exothermic process. While the adsorption of SLS and SDS were spontaneous, endothermic. The adsorption processes were complex physical-chemistry adsorption models, which are dominated by physisorption. Furthermore, this study found that the material had strong absorption abilities for anionic surfactants, the saturation adsorption capacity of ACCMs were 1220mg/g for SDBS, 888mg/g for SLS, and 825mg/g for SDS at pH 3.0 and 298K, respectively. The adsorption capacity was reduced only 5.7% after 8 cycles of the adsorption-desorption processes. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Sono-assisted adsorption of a textile dye on milk vetch-derived charcoal supported by silica nanopowder.

    PubMed

    Jorfi, Sahand; Darvishi Cheshmeh Soltani, Reza; Ahmadi, Mehdi; Khataee, Alireza; Safari, Mahdi

    2017-02-01

    This study was performed to assess the efficiency of silica nanopowder (SNP)/milk vetch-derived charcoal (MVDC) nanocomposite coupled with the ultrasonic irradiation named sono-adsorption process for treating water-contained Basic Red 46 (BR46) dye. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and Fourier transform infrared spectroscopy (FT-IR) were performed for the characterization of as-prepared adsorbent. The sono-assisted adsorption process was optimized using response surface optimization on the basis of central composite design by the application of quadratic model. Accordingly, the color removal can be retained more than 93% by an initial BR46 concentration of 8 mg/L, sonication time of 31 min, adsorbent dosage of 1.2 g/L and initial pH of 9. The pseudo-second order kinetic model described the sono-assisted adsorption of BR46 reasonably well (R 2  > 0.99). The intra-particular diffusion kinetic model pointed out that the sono-assisted adsorption of BR46 onto SNP/MVDC nanocomposite was diffusion controlled as well as that ultrasonication enhanced the diffusion rate. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Adsorption of DDT and PCB by Nanomaterials from Residual Soil.

    PubMed

    Taha, Mohd Raihan; Mobasser, Shariat

    2015-01-01

    This paper presents the findings of a study on adsorption of dichlorodiphenythreechloroethen (DDT) and polychlorinated biphenyls (PCBs) on three nanomaterials including Multi walled Carbon Nanotube (MWNT), nano-clay and nano-alumina. DDT and PCBs are of significant concern due their high toxicity and long environmental half-lives. Experiments were conducted using batch adsorption procedures at different DDT and PCBs concentrations, from 10 to 60 mg/L. The amounts of MWNT, nano-clay and Nano-alumina used were 0.25%, 0.50%, 0.75%, 1%, 2% and 10%. The adsorption of PCBs solution onto the MWNT, nano-clay and nano-alumina was characterized by an initial rapid adsorption which eventually became constant within 22, 20, and 17 hours, respectively. The adsorption of DDT solution onto the MWNT, nano-clay and nano-alumina was also characterized by an initial rapid adsorption which gradually became constant within 22, 22 and 16 hours, respectively. Results of this study indicated that MWNT was a better adsorbent material compared to nano-clay and nano-alumina for both contaminants in this study. While at 10% of MWNT 88.9% and 77% of DDT and PCB were removed by MWNT, respectively. The effect of pH and temperature were also investigated.

  16. Adsorption of DDT and PCB by Nanomaterials from Residual Soil

    PubMed Central

    Taha, Mohd Raihan; Mobasser, Shariat

    2015-01-01

    This paper presents the findings of a study on adsorption of dichlorodiphenythreechloroethen (DDT) and polychlorinated biphenyls (PCBs) on three nanomaterials including Multi walled Carbon Nanotube (MWNT), nano-clay and nano-alumina. DDT and PCBs are of significant concern due their high toxicity and long environmental half-lives. Experiments were conducted using batch adsorption procedures at different DDT and PCBs concentrations, from 10 to 60 mg/L. The amounts of MWNT, nano-clay and Nano-alumina used were 0.25%, 0.50%, 0.75%, 1%, 2% and 10%. The adsorption of PCBs solution onto the MWNT, nano-clay and nano-alumina was characterized by an initial rapid adsorption which eventually became constant within 22, 20, and 17 hours, respectively. The adsorption of DDT solution onto the MWNT, nano-clay and nano-alumina was also characterized by an initial rapid adsorption which gradually became constant within 22, 22 and 16 hours, respectively. Results of this study indicated that MWNT was a better adsorbent material compared to nano-clay and nano-alumina for both contaminants in this study. While at 10% of MWNT 88.9% and 77% of DDT and PCB were removed by MWNT, respectively. The effect of pH and temperature were also investigated. PMID:26659225

  17. Kinetic studies of adsorption of Cu (II) from aqueous solution by coriander seeds (Coriandrum Sativum)

    NASA Astrophysics Data System (ADS)

    Kadiri, L.; Lebkiri, A.; Rifi, E. H.; Ouass, A.; Essaadaoui, Y.; Lebkiri, I.; Hamad, H.

    2018-05-01

    The adsorption of copper ions Cu2+ by Coriandrum Sativum seeds (CSS) from aqueous solution was studied in order to highlight the importance of coriander seeds as a potential tool in the treatment of wastewaters containing heavy metals. The kinetic studies of adsorption of Cu (II) were discussed using the spectroscopic technique "Inducting Coupled Plasma" (ICP). The effects of initial copper ion concentration and contact time were determined. All results show that coriander seeds have, over their culinary and medicinal benefits, a significant adsorbent power of copper ions.

  18. The Accelerated Late Adsorption of Pulmonary Surfactant

    PubMed Central

    2011-01-01

    Adsorption of pulmonary surfactant to an air−water interface lowers surface tension (γ) at rates that initially decrease progressively, but which then accelerate close to the equilibrium γ. The studies here tested a series of hypotheses concerning mechanisms that might cause the late accelerated drop in γ. Experiments used captive bubbles and a Wilhelmy plate to measure γ during adsorption of vesicles containing constituents from extracted calf surfactant. The faster fall in γ reflects faster adsorption rather than any feature of the equation of state that relates γ to surface concentration (Γ). Adsorption accelerates when γ reaches a critical value rather than after an interval required to reach that γ. The hydrophobic surfactant proteins (SPs) represent key constituents, both for reaching the γ at which the acceleration occurs and for producing the acceleration itself. The γ at which rates of adsorption increase, however, is unaffected by the Γ of protein in the films. In the absence of the proteins, a phosphatidylethanolamine, which, like the SPs, induces fusion of the vesicles with the interfacial film, also causes adsorption to accelerate. Our results suggest that the late acceleration is characteristic of adsorption by fusion of vesicles with the nascent film, which proceeds more favorably when the Γ of the lipids exceeds a critical value. PMID:21417351

  19. Removal of Direct N Blue-106 from artificial textile dye effluent using activated carbon from orange peel: adsorption isotherm and kinetic studies.

    PubMed

    Khaled, Azza; El Nemr, Ahmed; El-Sikaily, Amany; Abdelwahab, Ola

    2009-06-15

    The purpose of this study is to suggest an efficient process, which does not require a huge investment for the removal of direct dye from wastewater. Activated carbon developed from agricultural waste material was characterized and utilized for the removal of Direct Navy Blue 106 (DNB-106) from wastewater. Systematic studies on DNB-106 adsorption equilibrium and kinetics by low-cost activated carbons were carried out. Adsorption studies were carried out at different initial concentrations of DNB-106 (50, 75, 100, 125 and 150 mg l(-1)), contact time (5-180 min), pH (2.0, 3.0, 4.7, 6.3, 7.2, 8.0, 10.3 and 12.7) and sorbent doses (2.0, 4.0 and 6.0 g l(-1)). Both Langmuir and Freundlich models fitted the adsorption data quite reasonably (R(2)>97). The maximum adsorption capacity was 107.53 mg g(-1) for 150 mg l(-1) of DNB-106 concentration and 2 g l(-1) carbon concentration. Various mechanisms were established for DNB-106 adsorption on developed adsorbents. The kinetic studies were conducted to delineate the effect of initial dye concentration, contact time and solid to liquid concentration. The developed carbon might be successfully used for the removal of DNB-106 from liquid industrial wastes.

  20. Characteristics and adsorption study of the activated carbon derived from municipal sewage sludge.

    PubMed

    Guo, Tiecheng; Yao, Sicong; Chen, Hengli; Yu, Xin; Wang, Meicheng; Chen, Yao

    2017-10-01

    Sewage sludge-based activated carbon is proved to be an efficient and low-cost adsorbent in treatment of various industrial wastewaters. The produced carbon had a well-developed pore structure and relatively low Brunauer-Emmett-Teller (BET) surface area. Adsorptive capacity of typical pollutants, i.e. copper Cu(II) and methylene blue (MB) on the carbon was studied. Adsorptions were affected by the initial solution pH, contact time and adsorbent dose. Results showed that adsorption of Cu(II) and MB on the produced carbon could reach equilibrium after 240 min. The average removal rate for Cu(II) on the carbon was high, up to 97% in weak acidic conditions (pH = 4-6) and around 98% for MB in a very wide pH range (pH = 2-12). The adsorption kinetics were well fitted by the pseudo-second order model, and both Langmuir and Freundlich isotherm models could well describe the adsorption process at room temperature. The theoretical maximum adsorption capacities of Cu(II) and MB on sewage sludge-based activated carbon were 114.94 mg/g and 125 mg/g, respectively. Compared with commercial carbon, the sewage sludge-based carbon was more suitable for heavy metal ions' removal than dyes'.

  1. Initial data on adsorption of Cs and Sr to the surfaces of microplastics with biofilm.

    PubMed

    Johansen, Mathew P; Prentice, Emily; Cresswell, Tom; Howell, Nick

    2018-10-01

    The adsorption of radiocesium and radiostrontium onto a range of natural materials has been well quantified, but not for the new media of environmental plastics, which may have enhanced adsorption due to surface-weathering and development of biofilms. Microplastic samples were deployed in freshwater, estuarine and marine conditions, then characterised using infrared spectroscopy to document changes to the plastic surface (vs interior). Synchrotron elemental mapping data revealed surfaces that were well-covered by accumulation of reactive water solutes and sulphur, but, in contrast, had highly discrete coverage of elements such as Fe and Ti, indicating adhered mineral/clay-associated agglomerates that may increase overall adsorption capacity. Plastics that had been deployed for nearly five months adsorbed radionuclides in both freshwater and estuarine conditions with the highest K d for cesium (Cs) in freshwater (80 ml g -1 ) and lowest for strontium (Sr) in estuarine conditions (5 ml g -1 ). The degree of Cs and Sr adsorption onto plastics appears to be approximately 2-3 orders of magnitude lower than for sediment reference values. While lower than for sediments, adsorption occurred on all samples and may indicate a significant radionuclide reservoir, given that plastics are relatively buoyant and mobile in water regimes, and are increasing in global aquatic systems. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

  2. Investigation of Zn2+ and Cd2+ Adsorption Performanceby Different Weathering Basalts

    NASA Astrophysics Data System (ADS)

    Xue, Q.; Shuo, Q.; Chen, H.

    2016-12-01

    Geological barriers play an important role in preventing pollution of groundwater. Basalts are common geological media; however, there have not been any studies that report the effect of basalt type on the metal ion adsorption performance. In this study, we explored the metal ion (Zn2+ and Cd2+) adsorption ability of two kinds of weathering basalts: the origin weathering basalt (WB) and the eluvial deposit (ED), both of which were derived from same basaltic formation. Characteristics of the sediments were examined by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Barrett-Joyner-Halenda (BJH) measurement and the rapid potentiometric titration (RPT) method. Batch experiments were performed to evaluate the Zn2+ and Cd2+ adsorption performance of WB and ED and how adsorption was affected by contact time, initial metal ion concentration, pH and ionic strength. Despite WB and ED having similar chemical compositions, WB exhibited better adsorption than ED likely due to the fact that WB was rougher and had more small-sized spherical structures and stronger electrostatic forces. The adsorption process fit the Freundlich isotherm model well. The adsorption efficiency decreased with a decrease of pH (from 4 to 2) and with increasing ionic strength. These results suggest that a geological barrier composed of WB media might be able to effectively sequester metallic contaminants to prevent them from reaching groundwater.

  3. Adsorption kinetics, isotherms and thermodynamics of atrazine removal using a banana peel based sorbent.

    PubMed

    Chaparadza, Allen; Hossenlopp, Jeanne M

    2012-01-01

    Atrazine removal from water by treated banana peels was studied. The effect of pH, contact time, initial atrazine concentration, and temperature were investigated. Batch experiments demonstrated that 15 g L(-1) adsorbent dosage removed 90-99% of atrazine from 1-150 ppm aqueous solutions. The removal was both pH and temperature dependent with the most atrazine removed between pH 7 and 8.2 and increased with increasing temperature. Equilibrium data fitted well to the Langmuir and Redlich-Peterson models in the concentration and temperature ranges investigated, with a maximum adsorption capacity of 14 mg g(-1). Simple mass transfer models were applied to the experimental data to examine the adsorption mechanism and it was found that both external mass transfer and intraparticle diffusion played important roles in the adsorption mechanisms. The enthalpy of atrazine adsorption was evaluated to be 67.8 ± 6.3 kJ mol(-l) with a Gibbs free energy of -5.7 ± 1.2 kJ mol(-1).

  4. Formation of Manganese Oxide Coatings onto Sand for Adsorption of Trace Metals from Groundwater.

    PubMed

    Tilak, A S; Ojewole, S; Williford, C W; Fox, G A; Sobecki, T M; Larson, S L

    2013-11-01

    Manganese oxide (MnO) occurs naturally in soil and has a high affinity for trace metals adsorption. In this work, we quantified the factors (pH; flow rate; use of oxidants such as bleach, HO, and O; initial Mn(II) concentrations; and two types of geologic media) affecting MnO coatings onto Ottawa and aquifer sand using batch and column experiments. The batch experiments consisted of manual and automated titration, and the column experiments mimicked natural MnO adsorption and oxidation cycles as a strategy for in situ adsorption. A Pb solution of 50 mg L was passed through MnO-coated sand at a flow rate of 4 mL min to determine its adsorption capacity. Batch experimental results showed that MnO coatings increased from pH 6 to 8, with maximum MnO coating occurring at pH 8. Regarding MnO coatings, bleach and O were highly effective compared with HO. The Ottawa sand had approximately twice the MnO coating of aquifer sand. The sequential increase in initial Mn(II) concentrations on both sands resulted in incremental buildup of MnO. The automated procedure enhanced MnO coatings by 3.5 times compared with manual batch experiments. Column results showed that MnO coatings were highly dependent on initial Mn(II) and oxidant concentrations, pH, flow rate, number of cycles (h), and the type of geologic media used. Manganese oxide coating exceeded 1700 mg kg for Ottawa sand and 130 mg kg for aquifer sand. The Pb adsorption exceeded 2200 mg kg for the Ottawa sand and 300 mg kg for the aquifer sand. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  5. Adsorptive removal of Cu(II) from aqueous solution and industrial effluent using natural/agricultural wastes.

    PubMed

    Singha, Biswajit; Das, Sudip Kumar

    2013-07-01

    The potentiality of low cost natural/agricultural waste biomasses for the removal of Cu(II) ion from aqueous solution has been investigated in batch experiments. The effect of various physico-chemical parameters such as initial pH, initial Cu(II) concentration, adsorbent dosage, contact time and temperature has been studied. The optimum pH for adsorption was found to be 6 for all adsorbents used. Kinetics data were best described by the pseudo-2nd-order model. The experimental data were fitted well with Freundlich and Halsey isotherm models. The diffusion coefficient and sorption energy indicated that the adsorption process was chemical in nature. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated, and it was observed that the adsorption process was spontaneous and endothermic. The mean sorption energy was calculated using Dubinin-Radushkevich isotherm model and it confirmed that the sorption process was chemical in nature. Different active functional groups were identified by FTIR studies which were responsible for Cu(II) ion adsorption process. Application study using electroplating industrial waste water and regeneration experiment of the adsorbent were also investigated. Design procedure for the batch process was also reported. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Protein adsorption in microengraving immunoassays.

    PubMed

    Song, Qing

    2015-10-16

    Microengraving is a novel immunoassay for characterizing multiple protein secretions from single cells. During the immunoassay, characteristic diffusion and kinetic time scales  and  determine the time for molecular diffusion of proteins secreted from the activated single lymphocytes and subsequent binding onto the glass slide surface respectively. Our results demonstrate that molecular diffusion plays important roles in the early stage of protein adsorption dynamics which shifts to a kinetic controlled mechanism in the later stage. Similar dynamic pathways are observed for protein adsorption with significantly fast rates and rapid shifts in transport mechanisms when  is increased a hundred times from 0.313 to 31.3. Theoretical adsorption isotherms follow the trend of experimentally obtained data. Adsorption isotherms indicate that amount of proteins secreted from individual cells and subsequently captured on a clean glass slide surface increases monotonically with time. Our study directly validates that protein secretion rates can be quantified by the microengraving immunoassay. This will enable us to apply microengraving immunoassays to quantify secretion rates from 10⁴-10⁵ single cells in parallel, screen antigen-specific cells with the highest secretion rate for clonal expansion and quantitatively reveal cellular heterogeneity within a small cell sample.

  7. Protein Adsorption in Microengraving Immunoassays

    PubMed Central

    Song, Qing

    2015-01-01

    Microengraving is a novel immunoassay forcharacterizing multiple protein secretions from single cells. During the immunoassay, characteristic diffusion and kinetic time scales τD and τK determine the time for molecular diffusion of proteins secreted from the activated single lymphocytes and subsequent binding onto the glass slide surface respectively. Our results demonstrate that molecular diffusion plays important roles in the early stage of protein adsorption dynamics which shifts to a kinetic controlled mechanism in the later stage. Similar dynamic pathways are observed for protein adsorption with significantly fast rates and rapid shifts in transport mechanisms when C0* is increased a hundred times from 0.313 to 31.3. Theoretical adsorption isotherms follow the trend of experimentally obtained data. Adsorption isotherms indicate that amount of proteins secreted from individual cells and subsequently captured on a clean glass slide surface increases monotonically with time. Our study directly validates that protein secretion rates can be quantified by the microengraving immunoassay. This will enable us to apply microengraving immunoassays to quantify secretion rates from 104–105 single cells in parallel, screen antigen-specific cells with the highest secretion rate for clonal expansion and quantitatively reveal cellular heterogeneity within a small cell sample. PMID:26501282

  8. The Adsorption of Cd(II) on Manganese Oxide Investigated by Batch and Modeling Techniques.

    PubMed

    Huang, Xiaoming; Chen, Tianhu; Zou, Xuehua; Zhu, Mulan; Chen, Dong; Pan, Min

    2017-09-28

    Manganese (Mn) oxide is a ubiquitous metal oxide in sub-environments. The adsorption of Cd(II) on Mn oxide as function of adsorption time, pH, ionic strength, temperature, and initial Cd(II) concentration was investigated by batch techniques. The adsorption kinetics showed that the adsorption of Cd(II) on Mn oxide can be satisfactorily simulated by pseudo-second-order kinetic model with high correlation coefficients (R² > 0.999). The adsorption of Cd(II) on Mn oxide significantly decreased with increasing ionic strength at pH < 5.0, whereas Cd(II) adsorption was independent of ionic strength at pH > 6.0, which indicated that outer-sphere and inner-sphere surface complexation dominated the adsorption of Cd(II) on Mn oxide at pH < 5.0 and pH > 6.0, respectively. The maximum adsorption capacity of Mn oxide for Cd(II) calculated from Langmuir model was 104.17 mg/g at pH 6.0 and 298 K. The thermodynamic parameters showed that the adsorption of Cd(II) on Mn oxide was an endothermic and spontaneous process. According to the results of surface complexation modeling, the adsorption of Cd(II) on Mn oxide can be satisfactorily simulated by ion exchange sites (X₂Cd) at low pH and inner-sphere surface complexation sites (SOCd⁺ and (SO)₂CdOH - species) at high pH conditions. The finding presented herein plays an important role in understanding the fate and transport of heavy metals at the water-mineral interface.

  9. The Adsorption of Cd(II) on Manganese Oxide Investigated by Batch and Modeling Techniques

    PubMed Central

    Huang, Xiaoming; Chen, Tianhu; Zou, Xuehua; Zhu, Mulan; Chen, Dong

    2017-01-01

    Manganese (Mn) oxide is a ubiquitous metal oxide in sub-environments. The adsorption of Cd(II) on Mn oxide as function of adsorption time, pH, ionic strength, temperature, and initial Cd(II) concentration was investigated by batch techniques. The adsorption kinetics showed that the adsorption of Cd(II) on Mn oxide can be satisfactorily simulated by pseudo-second-order kinetic model with high correlation coefficients (R2 > 0.999). The adsorption of Cd(II) on Mn oxide significantly decreased with increasing ionic strength at pH < 5.0, whereas Cd(II) adsorption was independent of ionic strength at pH > 6.0, which indicated that outer-sphere and inner-sphere surface complexation dominated the adsorption of Cd(II) on Mn oxide at pH < 5.0 and pH > 6.0, respectively. The maximum adsorption capacity of Mn oxide for Cd(II) calculated from Langmuir model was 104.17 mg/g at pH 6.0 and 298 K. The thermodynamic parameters showed that the adsorption of Cd(II) on Mn oxide was an endothermic and spontaneous process. According to the results of surface complexation modeling, the adsorption of Cd(II) on Mn oxide can be satisfactorily simulated by ion exchange sites (X2Cd) at low pH and inner-sphere surface complexation sites (SOCd+ and (SO)2CdOH− species) at high pH conditions. The finding presented herein plays an important role in understanding the fate and transport of heavy metals at the water–mineral interface. PMID:28956849

  10. Preparation of new nano magnetic material Fe3O4@g-C3N4 and good adsorption performance on uranium ion

    NASA Astrophysics Data System (ADS)

    Long, Wei; Liu, Huijun; Yan, Xueming; Fu, Li

    2018-03-01

    A new nano magnetic material Fe3O4@g-C3N4 was prepared by deposition reduction method, which performed good adsorption performance to uranium ion. Characterization results showed that the g-C3N4 particles were wrapped around the nano magnetic Fe3O4 particles, and the textural properties of this material was improved, so the adsorption performance to uranium ion was good. Adsorption experiments of this material demonstrated that the optimum pH value was 10, the optimum mass of adsorbent was 6.5 mg and the optimum adsorption time was 150 min in the initial concentration of 140 mg/L uranium ion solution system, and the maximum adsorption capacity was up to 352.1 mg/g and the maximum adsorption rate was more than 90%.

  11. Adsorption equilibrium and dynamics of gasoline vapors onto polymeric adsorbents.

    PubMed

    Jia, Lijuan; Yu, Weihua; Long, Chao; Li, Aimin

    2014-03-01

    The emission of gasoline vapors is becoming a significant environmental problem especially for the population-dense area and also results in a significant economic loss. In this study, adsorption equilibrium and dynamics of gasoline vapors onto macroporous and hypercrosslinked polymeric resins at 308 K were investigated and compared with commercial activated carbon (NucharWV-A 1100). The results showed that the equilibrium and breakthrough adsorption capacities of virgin macroporous and hypercrosslinked polymeric resins were lower than virgin-activated carbon. Compared with origin adsorbents, however, the breakthrough adsorption capacities of the regenerated activated carbon for gasoline vapors decreased by 58.5 % and 61.3 % when the initial concentration of gasoline vapors were 700 and 1,400 mg/L, while those of macroporous and hypercrosslinked resins decreased by 17.4 % and 17.5 %, and 46.5 % and 45.5 %, respectively. Due to the specific bimodal property in the region of micropore (0.5-2.0 nm) and meso-macropore (30-70 nm), the regenerated hypercrosslinked polymeric resin exhibited the comparable breakthrough adsorption capacities with the regenerated activated carbon at the initial concentration of 700 mg/L, and even higher when the initial concentration of gasoline vapors was 1,400 mg/L. In addition, 90 % of relative humidity had ignorable effect on the adsorption of gasoline vapors on hypercrosslinked polymeric resin. Taken together, it is expected that hypercrosslinked polymeric adsorbent would be a promising adsorbent for the removal of gasoline vapors from gas streams.

  12. Adsorption Effectivity Test of Andisols Clay-Zeolite (ACZ) Composite as Chromium Hexavalent (Cr(VI)) Ion Adsorbent

    NASA Astrophysics Data System (ADS)

    Pranoto; Masykur, A.; Nugroho, Y. A.

    2018-03-01

    Adsorption of chromium hexavalent (Cr(VI)) ion in aqueous solution was investigated. This research was purposed to study the influence of the composition of ACZ, temperature activation, and contact time against adsorption capacity of Cr(VI) ion in aqueous solution. Determination of adsorption effectivity using several parameter such as composition variation of ACZ, contact time, pH, activation temperature, and concentration. In this research, andisol clay and zeolite has been activated with NaOH 3 M and 1 M, respectively. Temperature variation used 100, 200, and 400°C. While composition variation ACZ used 0:100, 25:75, 50:50, 75:25, 100:0. The pH variation was used 2 – 6 and concentration variation using 2, 4, 6, 8, 10, and 12 ppm. Characterization in this research used such as UV-Vis, Surface Area Analyzer (SAA) and Acidity Analysis. Result of this research is known that optimum composition of ACZ was 50:50 with calcination temperature 100°C. Optimum adsorption of Cr(VI) at pH 4 with removal percentage 76.10 % with initial concentration 2 ppm and adsorption capacity is 0.16 mg/g. Adsorption isotherm following freundlich isotherm with value Kf = 0.17 mg/g and value n is 0.963. Based on results, ACZ composite can be used as Cr(VI) ion adsorbents in aqueous solutions.

  13. Statistical inference in single molecule measurements of protein adsorption

    NASA Astrophysics Data System (ADS)

    Armstrong, Megan J.; Tsitkov, Stanislav; Hess, Henry

    2018-02-01

    Significant effort has been invested into understanding the dynamics of protein adsorption on surfaces, in particular to predict protein behavior at the specialized surfaces of biomedical technologies like hydrogels, nanoparticles, and biosensors. Recently, the application of fluorescent single molecule imaging to this field has permitted the tracking of individual proteins and their stochastic contribution to the aggregate dynamics of adsorption. However, the interpretation of these results is complicated by (1) the finite time available to observe effectively infinite adsorption timescales and (2) the contribution of photobleaching kinetics to adsorption kinetics. Here, we perform a protein adsorption simulation to introduce specific survival analysis methods that overcome the first complication. Additionally, we collect single molecule residence time data from the adsorption of fibrinogen to glass and use survival analysis to distinguish photobleaching kinetics from protein adsorption kinetics.

  14. A study of Reactive Red 198 adsorption on iron filings from aqueous solutions.

    PubMed

    Azhdarpoor, Abooalfazl; Nikmanesh, Roya; Khademi, Fahime

    2014-01-01

    In recent years, reactive dyes have been widely used in textile industries with particular efficiency. They dyes are often toxic, carcinogenic and mutagenic. Improper treatment and non-scientific disposal of dyed wastewater from these industries into water sources has created many environmental problems and concerns around the world. The purpose of the present study is to investigate the efficiency of iron filings in adsorption of Reactive Red 198 from aqueous solutions. This study was conducted using an experimental method at the laboratory scale. In this study, the effects of operating parameters such as pH (1-11), initial dye concentration (40-400 mg/L), contact time (5-120 min) and iron dose (0.1-1 g) with a mesh of<100 were studied. Dye concentration was determined using a spectrophotometer at a wavelength of 520 nm. The results indicated that maximum adsorption capacity of the dye in question was obtained at pH 3, contact time of 60 min and adsorbent dose of 1 g. At initial dye concentration of 100 and 200 mg/L, by increasing the dose of waste iron from 0.1 to 1 g, the removal percentage increased from approximately 76.89% to 97.28% and from 22.64% to 68.03%, respectively. At pH 3, contact time of 5 min and constant waste iron dose of 0.8 g, the dye removal efficiency was 85.34%. By increasing the contact time to 120 min, the removal efficiency increased to 99.2%. Welding iron waste as an inexpensive and available adsorbent has an optimum ability for adsorption of Reactive Red 198 from aqueous solutions.

  15. Dissociative adsorption of a multifunctional compound on a semiconductor surface: a theoretical study of the adsorption of hydroxylamine on Ge(100).

    PubMed

    Park, Hyunkyung; Kim, Do Hwan

    2018-06-06

    The adsorption behavior of hydroxylamine on a Ge(100) surface was investigated using density functional theory (DFT) calculations. These calculations predicted that hydroxylamine, a multifunctional compound consisting of a hydroxyl group and an amine group, would initially become adsorbed through N-dative bonding, or alternatively through the hydroxyl group via O-H dissociative adsorption. An N-O dissociative reaction may also occur, mainly via N-dative molecular adsorption, and the N-O dissociative product was calculated to be the most stable of all the possible adsorption structures. The calculations furthermore indicated the formation of the N-O dissociative product from the N-dative structure to be nearly barrierless and the dissociated hydroxyl and amine groups to be bonded to two Ge atoms of adjacent Ge dimers. Simulated STM images suggested the change in electron density that would occur upon adsorption of hydroxylamine in various adsorption configurations, and specifically indicated the N-O dissociative product to have greater electron density around the amine groups, and the hydroxyl groups to mainly contribute electron density to the unoccupied electronic states.

  16. Modeling adsorption of copper(II), cobalt(II) and nickel(II) metal ions from aqueous solution onto a new carboxylated sugarcane bagasse. Part II: Optimization of monocomponent fixed-bed column adsorption.

    PubMed

    Xavier, Amália Luísa Pedrosa; Adarme, Oscar Fernando Herrera; Furtado, Laís Milagres; Ferreira, Gabriel Max Dias; da Silva, Luis Henrique Mendes; Gil, Laurent Frédéric; Gurgel, Leandro Vinícius Alves

    2018-04-15

    In the second part of this series of studies, the monocomponent adsorption of Cu 2+ , Co 2+ and Ni 2+ onto STA adsorbent in a fixed-bed column was investigated and optimized using a 2 2 central composite design. The process variables studied were: initial metal ion concentration and spatial time, and the optimized responses were: adsorption capacity of the bed (Q max ), efficiency of the adsorption process (EAP), and effective use of the bed (H). The higher Q max for Cu 2+ , Co 2+ and Ni 2+ were 1.060, 0.800 and 1.029 mmol/g, respectively. The breakthrough curves were modeled by the original Thomas and Bohart-Adams models. The changes in enthalpy (Δ ads H°) of adsorption of the metal ions onto STA were determined by isothermal titration calorimetry (ITC). The values of Δ ads H° were in the range of 3.0-6.8 kJ/mol, suggesting that the adsorption process involved physisorption. Desorption (E des ) and re-adsorption (E re-ads ) of metal ions from the STA adsorbent were also investigated in batch mode, and the optimum conditions were applied for three cycles of adsorption/desorption in a fixed bed column. For these cycles, the lowest values of E des and E re-ads were 95 and 92.3%, respectively, showing that STA is a promising candidate for real applications on a large scale. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. Adsorption/reduction of Hg(II) and Pb(II) from aqueous solutions by using bone ash/nZVI composite: effects of aging time, Fe loading quantity and co-existing ions.

    PubMed

    Gil, Antonio; Amiri, Mohammad Javad; Abedi-Koupai, Jahangir; Eslamian, Saeid

    2018-01-01

    In this research, a versatile and highly efficient method for the stabilization of nanoscale zerovalent iron particles (nZVI) on the surface of ostrich bone ash (OBA) was presented as a novel inorganic adsorbent (OBA/nZVI) for the removal of Hg(II) and Pb(II) ions from aqueous solutions, even after 1 year of storage under room conditions. The removal behavior of the OBA/nZVI was assessed as a function of the initial pH, contact time, initial pollutants concentration, temperature, amount of adsorbent, effect of competitive metal ions, and ionic strength. The synthesized adsorbent was characterized by several techniques including N 2 adsorption at - 196 °C, FT-IR spectroscopy, scanning electron microscopy, X-ray diffraction, and zeta potential. The results confirmed that the OBA is a good candidate as support of nZVI. The maxima adsorption capacity for Hg(II) and Pb(II) ions found from experimental results were 170 and 160 mg g -1 , when the loading quantities of Fe were 20%. The equilibrium sorption data obeyed a Langmuir-Freundlich isotherm type model. The kinetic data of the adsorption followed the mechanism of the pseudo-second-order model. The thermodynamic experiments indicated that the removal of metal ions were feasible, endothermic, and spontaneous. It can be found that fresh and aged OBA/nZVI maintained its usability even after five cycles in the order: fresh (OBA/nZVI)-Hg(II) > fresh (OBA/nZVI)-Pb(II) > aged (OBA/nZVI)-Hg(II) > aged (OBA/nZVI)-Pb(II), which indicate that OBA/nZVI can be regenerated as adsorbent. The existence of Fe in the OBA/nZVI was proved by SEM-EDX results and X-ray diffraction analysis also confirmed adsorption/reduction of some of the Hg(II) to Hg 0 and Pb(II) to Pb 0 .

  18. Adsorption and leaching behaviour of bispyribac-sodium in soils.

    PubMed

    Singh, Neera; Singh, S B

    2015-01-01

    Adsorption-desorption of the herbicide bispyribac-sodium was studied in four Indian soil types. Bispyribac-sodium was poorly adsorbed in the four soils and adsorption decreased with an increase in the herbicide concentration in solution. Freundlich adsorption coefficient (Kf) values for bispyribac-sodium ranged between 0.37 and 0.87. Slope (1/n) values varied from 0.2 to 0.31 suggesting that bispyribac-sodium adsorption was highly dependent on its initial concentration in solution. Bispyribac-sodium adsorption showed a positive correlation with soil pH (r = 0.809) and clay content (r = 0.699) while no correlation was observed with the organic carbon (r = 0.063) content. Sorbed herbicide was completely desorbed during a single desorption step suggesting that the herbicide was bound by weak adsorptive forces. Leaching studies of herbicide in soil 1 packed column indicated complete loss of soil applied herbicide under a simulated rainfall equivalent to 162 mm.

  19. Adsorption of Methylene Blue, Bromophenol Blue, and Coomassie Brilliant Blue by α-chitin nanoparticles

    PubMed Central

    Dhananasekaran, Solairaj; Palanivel, Rameshthangam; Pappu, Srinivasan

    2015-01-01

    Expelling of dyestuff into water resource system causes major thread to the environment. Adsorption is the cost effective and potential method to remove the dyes from the effluents. Therefore, an attempt was made to study the adsorption of dyestuff (Methylene Blue (MB), Bromophenol Blue (BPB) and Coomassie Brilliant Blue (CBB)) by α-chitin nanoparticles (CNP) prepared from Penaeus monodon (Fabricius, 1798) shell waste. On contrary to the most recognizable adsorption studies using chitin, this is the first study using unique nanoparticles of ⩽50 nm used for the dye adsorption process. The results showed that the adsorption process increased with increase in the concentration of CNP, contact time and temperature with the dyestuff, whereas the adsorption process decreased with increase in the initial dye concentration and strong acidic pH. The results from Fourier transform infrared (FTIR) spectroscopy confirmed that the interaction between dyestuff and CNP involved physical adsorption. The adsorption process obeys Langmuir isotherm (R2 values were 0.992, 0.999 and 0.992 for MB, BPB and CBB, and RL value lies between 0 and 1 for all the three dyes) and pseudo second order kinetics (R2 values were 0.996, 0.999 and 0.996 for MB, BPB and CBB) more effectively. The isotherm and kinetic models confirmed that CNP can be used as a suitable adsorbent material for the removal of dyestuff from effluents. PMID:26843977

  20. Modeling the effect of adsorption on the degradation rate of propiconazole in profiles of Polish Luvisols.

    PubMed

    Paszko, Tadeusz; Jankowska, Monika

    2018-06-18

    Laboratory adsorption and degradation studies were carried out to determine the effect of time-dependent adsorption on propiconazole degradation rates in samples from three Polish Luvisols. Strong propiconazole adsorption (organic carbon normalized adsorption coefficients K oc in the range of 1217-7777 mL/g) was observed in batch experiments, with a typical biphasic mechanism with a fast initial step followed by the time-dependent step, which finished within 48 h in the majority of soils. The time-dependent step observed in incubation experiments was longer (duration from 5 to 23 d), and its contribution to total adsorption was from 20% to 34%. The half-lives obtained at 25 °C and 40% maximum water holding capacity of soil, were in the range of 34.7-112.9 d in the Ap horizon and in the range of 42.3-448.8 d for subsoils. The very strong correlations, between degradation rates in pore water and soil organic carbon and soil microbial activity, indicated that microbial degradation of propiconazole was most likely the only significant process responsible for the decay of this compound under aerobic conditions for the whole of the examined soil profiles. Modeling of the processes showed that only models coupling adsorption and degradation were able to correctly describe the experimental data. The analysis of the bioavailability factor values showed that degradation was not limited by the rate of propiconazole desorption from soil, but sorption affected the degradation rate by decreasing its availability for microorganisms. Copyright © 2018. Published by Elsevier Inc.

  1. Detailed Study of BSA Adsorption on Micro- and Nanocrystalline Diamond/β-SiC Composite Gradient Films by Time-Resolved Fluorescence Microscopy.

    PubMed

    Handschuh-Wang, Stephan; Wang, Tao; Druzhinin, Sergey I; Wesner, Daniel; Jiang, Xin; Schönherr, Holger

    2017-01-24

    The adsorption of bovine serum albumin (BSA) on micro- and nanocrystalline diamond/β-SiC composite films synthesized using the hot filament chemical vapor deposition (HFCVD) technique has been investigated by confocal fluorescence lifetime imaging microscopy. BSA labeled with fluorescein isothiocyanate (FITC) was employed as a probe. The BSA FITC conjugate was found to preferentially adsorb on both O-/OH-terminated microcrystalline and nanocrystalline diamond compared to the OH-terminated β-SiC, resulting in an increasing amount of BSA adsorbed to the gradient surfaces with an increasing diamond/β-SiC ratio. The different strength of adsorption (>30 times for diamond with a grain size of 570 nm) coincides with different surface energy parameters and differing conformational changes upon adsorption. Fluorescence data of the adsorbed BSA FITC on the gradient film with different diamond coverage show a four-exponential decay with decay times of 3.71, 2.54, 0.66, and 0.13 ns for a grain size of 570 nm. The different decay times are attributed to the fluorescence of thiourea fluorescein residuals of linked FITC distributed in BSA with different dye-dye and dye-surface distances. The longest decay time was found to correlate linearly with the diamond grain size. The fluorescence of BSA FITC undergoes external dynamic fluorescence quenching on the diamond surface by H- and/or sp 2 -defects and/or by amorphous carbon or graphite phases. An acceleration of the internal fluorescence concentration quenching in BSA FITC because of structural changes of albumin due to adsorption, is concluded to be a secondary contributor. These results suggest that the micro- and nanocrystalline diamond/β-SiC composite gradient films can be utilized to spatially control protein adsorption and diamond crystallite size, which facilitates systematic studies at these interesting (bio)interfaces.

  2. CARBON ADSORPTION FOR INDOOR AIR CLEANING

    EPA Science Inventory

    The paper discusses the use of carbon adsorption for indoor air cleaning, focusing on the removal of volatile organic compounds (VOCs) using granular activated carbon (GAC). It addresses GAC performance in two directions. Initially, it presents performance measurements for GAC at...

  3. Simultaneously efficient adsorption and photocatalytic degradation of tetracycline by Fe-based MOFs.

    PubMed

    Wang, Dongbo; Jia, Feiyue; Wang, Hou; Chen, Fei; Fang, Ying; Dong, Wenbo; Zeng, Guangming; Li, Xiaoming; Yang, Qi; Yuan, Xingzhong

    2018-06-01

    Recently, Fe-based metal-organic frameworks (MOFs) have attracted increasing attention and been widely used. To date, however, it is unknown whether they can be employed to degrade tetracycline, one of the most widely used antibiotics. This work therefore aims to provide such support by comparing the performance of three Fe-based MOFs (namely, Fe-MIL-101, Fe-MIL-100, and Fe-MIL-53) in removing tetracycline. Experimental results showed that Fe-MIL-101 exhibited the best performance in tetracycline removal, with 96.6% of tetracycline being removed (initial tetracycline concentration at 50 mg/L) while Fe-MIL-100 and Fe-MIL-53 removed 57.4% and 40.6% under the same conditions. Additionally, the effects of adding dosage, adsorption time, and initial concentration of tetracycline on degradation efficiency were examined. It was found that the adsorption and photocatalytic degradation effect was better with the increase of time, the optimum dosage of Fe-MIL-101 was 0.5 g/L and the removal efficiency decreased with the increasing of initial tetracycline concentrations. Moreover, the trapping experiments and ESR tests indicated that O 2 -, OH and h + were the main active species in photocatalytic degradation process of tetracycline. Due to its high removal efficiency and simple synthesis, it could be used as a potential catalyst for degradation of tetracycline and other antibiotics. Copyright © 2018 Elsevier Inc. All rights reserved.

  4. Rice husk grafted PMAA by ATRP in aqueous phase and its adsorption for Ce3+

    NASA Astrophysics Data System (ADS)

    Lin, Chao; Luo, Wenjun; Chen, Jindong; Zhou, Qi

    2017-12-01

    A monolithic biomass adsorbent, rice husk grafted poly (methyl acrylic acid) (RH-g-PMAA), was successfully synthesized via surface-initiated atom transfer radical polymerization (ATRP) through heterogeneous reactions in aqueous phase. Its adsorption capacity for Ce3+ reaches 122.51 mg g-1, which is about 12 times higher than that of raw rice husk. The experimental result on desorption and reusability shows that the adsorption capacity is still higher than 100 mg g-1 after six cycles and the desorption rate is almost 100% in every cycle. RH-g-PMAA can be separated from water easily because of its integrity.

  5. Adsorption of Direct Blue 53 dye from aqueous solutions by multi-walled carbon nanotubes and activated carbon.

    PubMed

    Prola, Lizie D T; Machado, Fernando M; Bergmann, Carlos P; de Souza, Felipe E; Gally, Caline R; Lima, Eder C; Adebayo, Matthew A; Dias, Silvio L P; Calvete, Tatiana

    2013-11-30

    Multi-walled carbon nanotubes (MWCNT) and powder activated carbon (PAC) were used as adsorbents for adsorption of Direct Blue 53 dye (DB-53) from aqueous solutions. The adsorbents were characterised using Raman spectroscopy, N2 adsorption/desorption isotherms, and scanning and transmission electron microscopy. The effects of initial pH, contact time and temperature on adsorption capacity of the adsorbents were investigated. At pH 2.0, optimum adsorption of the dye was achieved by both adsorbents. Equilibrium contact times of 3 and 4 h were achieved by MWCNT and PAC adsorbents, respectively. The general order kinetic model provided the best fit of the experimental data compared to pseudo-first order and pseudo-second order kinetic adsorption models. For DB-53 dye, the equilibrium data (298-323 K) were best fitted to the Sips isotherm model. The maximum sorption capacity for adsorption of the dye occurred at 323 K, with the values of 409.4 and 135.2 mg g(-1) for MWCNT and PAC, respectively. Studies of adsorption/desorption were conducted and the results showed that DB-53 loaded MWCNT could be regenerated (97.85%) using a mixture 50% acetone + 50% of 3 mol L(-1) NaOH. Simulated dye house effluents were used to evaluate the application of the adsorbents for effluent treatment (removal of 99.87% and 97.00% for MWCNT and PAC, respectively, were recorded). Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. On irreversible adsorption of electron-donating compounds in aqueous solution

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tamon, Hajime; Atsushi, Masanori; Okazaki, Morio

    Activated carbons and synthetic adsorbents have been used for liquid purification and wastewater treatment. The feasibility of an adsorption process depends greatly on the cost of regeneration of spent adsorbents. If irreversible adsorption occurs, regeneration of spent adsorbent is very difficult. Hence, it is very important to understand why irreversible adsorption appears in aqueous solution. In the adsorption of electron-donating compounds such as phenol, aniline, L-phenylalanine, and L-tyrosine from aqueous solution, irreversibility was observed on activated carbon and graphite. The compounds, except L-tyrosine, were reversibly adsorbed on a synthetic adsorbent. In the case where the carbonaceous adsorbents contacted the aqueousmore » solution containing electron-donating compounds for a long time, the irreversible amount adsorbed increased with the contact time. A two-state adsorption model was used to explain why the irreversible adsorption of electron-donating compound appears in aqueous solution. First, the compound is adsorbed in the precursor state for irreversible adsorption, and then moves into its irreversible state over a potential energy barrier after a long contact time. The appearance of irreversible adsorption was qualitatively explained by the two-state adsorption model.« less

  7. Influence of surface roughness on cetyltrimethylammonium bromide adsorption from aqueous solution.

    PubMed

    Wu, Shuqing; Shi, Liu; Garfield, Lucas B; Tabor, Rico F; Striolo, Alberto; Grady, Brian P

    2011-05-17

    The influence of surface roughness on surfactant adsorption was studied using a quartz crystal microbalance with dissipation (QCM-D). The sensors employed had root-mean-square (R) roughness values of 2.3, 3.1, and 5.8 nm, corresponding to fractal-calculated surface area ratios (actual/nominal) of 1.13, 1.73, and 2.53, respectively. Adsorption isotherms measured at 25 °C showed that adsorbed mass of cetyltrimethylammonium bromide per unit of actual surface area below 0.8 cmc, or above 1.2 cmc, decreases as the surface roughness increases. At the cmc, both the measured adsorbed amount and the measured dissipation increased dramatically on the rougher surfaces. These results are consistent with the presence of impurities, suggesting that roughness exacerbates well-known phenomena reported in the literature of peak impurity-related adsorption at the cmc. The magnitude of the increase, especially in dissipation, suggests that changes in adsorbed amount may not be the only reason for the observed results, as aggregates at the cmc on rougher surfaces are more flexible and likely contain larger amounts of solvent. Differences in adsorption kinetics were also found as a function of surface roughness, with data showing a second, slower adsorption rate after rapid initial adsorption. A two-rate Langmuir model was used to further examine this effect. Although adsorption completes faster on the smoother surfaces, initial adsorption at zero surface coverage is faster on the rougher surfaces, suggesting the presence of more high-energy sites on the rougher surfaces.

  8. Effect of Micellization on the Adsorption Kinetics of Polymeric Surfactants to the Solid/Water Interface

    NASA Astrophysics Data System (ADS)

    Toomey, Ryan; Tirrell, Matthew

    2002-03-01

    We have studied the adsorption kinetics of two classes of hydrophobic/ionic diblock copolymer surfactants in aqueous environments to understand the role that micellization plays in the adsorption process. The two systems studied were poly(t-butyl styrene)-block-poly(styrene sulfonate) (PtBS-b-PSS) and polystyrene-block-poly(acrylic acid) (PS-b-PAA). It is found that by changing the hydrophobicity of the adsorbing surface, micelle adsorption can be turned on or off. When micelle adsorption occurs, the initial adsorption rate is always slower than the supply rate of micelles to the surface, indicating “reaction-limited” adsorption. Since these micelles have essentially frozen cores, the adsorption cannot be explained by the release of unimers from the micelles. Rather, micelles directly adsorb, and they have to overcome the potential barrier imposed by their corona. Due to micellization, the adsorption rate can also be a complex function of ionic strength. A regime was found where the initial adsorption rate decreased with increasing ionic strength. This anomaly can be explained by the onset of micellization. As the salt concentration is increased, more micelles are formed. However micelles adsorb roughly an order of magnitude slower than free chains. Therefore, if increasing the ionic strength produces more micelles, the adsorption rate will simultaneously decrease.

  9. Synthesis, characterization and application of Lagerstroemia speciosa embedded magnetic nanoparticle for Cr(VI) adsorption from aqueous solution.

    PubMed

    Srivastava, Shalini; Agrawal, Shashi Bhushan; Mondal, Monoj Kumar

    2017-05-01

    Lagerstroemia speciosa bark (LB) embedded magnetic nanoparticles were prepared by co-precipitation of Fe 2+ and Fe 3+ salt solution with ammonia and LB for Cr(VI) removal from aqueous solution. The native LB, magnetic nanoparticle (MNP), L. speciosa embedded magnetic nanoparticle (MNPLB) and Cr(VI) adsorbed MNPLB particles were characterized by SEM-EDX, TEM, BET-surface area, FT-IR, XRD and TGA methods. TEM analysis confirmed nearly spherical shape of MNP with an average diameter of 8.76nm and the surface modification did not result in the phase change of MNP as established by XRD analysis, while led to the formation of secondary particles of MNPLB with diameter of 18.54nm. Characterization results revealed covalent binding between the hydroxyl group of MNP and carboxyl group of LB particles and further confirmed its physico-chemical nature favorable for Cr(VI) adsorption. The Cr(VI) adsorption on to MNPLB particle as an adsorbent was tested under different contact time, initial Cr(VI) concentration, adsorbent dose, initial pH, temperature and agitation speed. The results of the equilibrium and kinetics of adsorption were well described by Langmuir isotherm and pseudo-second-order model, respectively. The thermodynamic parameters suggest spontaneous and endothermic nature of Cr(VI) adsorption onto MNPLB. The maximum adsorption capacity for MNPLB was calculated to be 434.78mg/g and these particles even after Cr(VI) adsorption were collected effortlessly from the aqueous solution by a magnet. The desorption of Cr(VI)-adsorbed MNPLB was found to be more than 93.72% with spent MNPLB depicting eleven successive adsorption-desorption cycles. Copyright © 2016. Published by Elsevier B.V.

  10. The application of silicalite-1/fly ash cenosphere (S/FAC) zeolite composite for the adsorption of methyl tert-butyl ether (MTBE).

    PubMed

    Lu, Jia; Xu, Fang; Wang, Deju; Huang, Jue; Cai, Weimin

    2009-06-15

    Silicalite-1/fly ash cenosphere (S/FAC) zeolite composite has been applied for batch adsorption of methyl tert-butyl ether (MTBE) from water systems. Here the key experimental conditions, including the ratio of initial MTBE concentration to the amount weight of S/FAC, adsorption time and temperature, have been discussed in detail. The results show that approximately 93-95% MTBE could be adsorbed with initial concentration of MTBE solution 1000 microg l(-1). The column flow-through experiments also prove the high capacity of S/FAC composite for MTBE removal. The distinct advantages of S/FAC zeolite composite as adsorbent lie in (1) enhanced adsorption rate and capacity based on hierarchical micro and meso/macroporosity of S/FAC; (2) more easily operation and recycling process by assembly of nano-sized silicalite-1 zeolite on FAC support.

  11. Initial stages of benzotriazole adsorption on the Cu(111) surface

    NASA Astrophysics Data System (ADS)

    Grillo, Federico; Tee, Daniel W.; Francis, Stephen M.; Früchtl, Herbert; Richardson, Neville V.

    2013-05-01

    Benzotriazole (BTAH) has been used as a copper corrosion inhibitor since the 1950s; however, the molecular level detail of how inhibition occurs remains a matter of debate. The onset of BTAH adsorption on a Cu(111) single crystal was investigated via scanning tunnelling microscopy (STM), vibrational spectroscopy (RAIRS) and supporting DFT modelling. BTAH adsorbs as anionic (BTA-), CuBTA is a minority species, while Cu(BTA)2, the majority of the adsorbed species, form chains, whose sections appear to diffuse in a concerted manner. The copper surface appears to reconstruct in a (2 × 1) fashion.Benzotriazole (BTAH) has been used as a copper corrosion inhibitor since the 1950s; however, the molecular level detail of how inhibition occurs remains a matter of debate. The onset of BTAH adsorption on a Cu(111) single crystal was investigated via scanning tunnelling microscopy (STM), vibrational spectroscopy (RAIRS) and supporting DFT modelling. BTAH adsorbs as anionic (BTA-), CuBTA is a minority species, while Cu(BTA)2, the majority of the adsorbed species, form chains, whose sections appear to diffuse in a concerted manner. The copper surface appears to reconstruct in a (2 × 1) fashion. Electronic supplementary information (ESI) available: Calculated IR spectra, RAIRS assignments, modeling details, statistics on diffusion, experimental details, additional STM images, movie low coverage diffusing species. See DOI: 10.1039/c3nr00724c

  12. Adsorption and desorption of cationic malachite green dye on cellulose nanofibril aerogels.

    PubMed

    Jiang, Feng; Dinh, Darren M; Hsieh, You-Lo

    2017-10-01

    Ultra-light aerogels have been assembled from cellulose nanofibrils into hierarchically macroporous (several hundred μm) honeycomb cellular structure surrounded with mesoporous (8-60nm) thin walls. The high specific surface (193m 2 /g) and surface carboxyl content (1.29mmol/g) of these aerogels were demonstrated to be highly capable of removing cationic malachite green (MG) dye from aqueous media. The rapid MG adsorption was driven by electrostatic interactions and followed a pseudo-second-order adsorption kinetic and monolayer Langmuir adsorption isotherm. At a low 1:5mg/mL aerogel/MG ratio, both initial MG adsorption rate (2.3-59.8mgg -1 min -1 ) and equilibrium adsorption capacity (53.0-203.7mgg -1 ) increased with increasing initial MG concentrations from 10 to 200mg/L, reaching a maximum adsorption of 212.7mgg -1 . The excellent dye removal efficiency was demonstrated by complete MG removal through four repetitive adsorptions at a low 1:5mg/mL aerogel/MG ratio and 10mg/L dye concentration as well as 92% MG adsorption in a single batch at one order of magnitude higher10:5mg/mL aerogel/MG ratio and 100mg/L dye concentration. The adsorbed MG in aerogels could be desorbed in aqueous media by increasing ionic strength, demonstrating facile recovery of both dye and aerogel as well as the robust capability of this aerogel for repetitive applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Adsorption of dissolved Reactive red dye from aqueous phase onto activated carbon prepared from agricultural waste.

    PubMed

    Senthilkumaar, S; Kalaamani, P; Porkodi, K; Varadarajan, P R; Subburaam, C V

    2006-09-01

    The adsorption of Reactive red dye (RR) onto Coconut tree flower carbon (CFC) and Jute fibre carbon (JFC) from aqueous solution was investigated. Adsorption studies were carried out at different initial dye concentrations, initial solution pH and adsorbent doses. The kinetic studies were also conducted; the adsorption of Reactive red onto CFC and JFC followed pseudosecond-order rate equation. The effective diffusion coefficient was evaluated to establish the film diffusion mechanism. Quantitative removal of Reactive red dye was achieved at strongly acidic conditions for both the carbons studied. The adsorption isotherm data were fitted well to Langmuir isotherm and the adsorption capacity were found to be 181.9 and 200 mg/g for CFC and JFC, respectively. The overall rate of dye adsorption appeared to be controlled by chemisorption, in this case in accordance with poor desorption studies.

  14. Prediction of equilibrium parameters of adsorption of lead (II) ions onto diatomite

    NASA Astrophysics Data System (ADS)

    Salman, Taylan; Ardalı, Yüksel; Gamze Turan, N.

    2013-04-01

    Heavy metals from industrial wastewaters are one of the most important environmental issues to be solved today. Due to their toxicity and nonbiodegradable nature, heavy metals cause environmental and public health problems. Various techniques have been developed to remove heavy metals from aqueous solutions. These include chemical precipitation, reverse osmosis, ion Exchange and adsorption. Among them, adsorption is considered to be a particularly competitive and effective process for the removal of heavy metals from aqueous solutions. There is growing interest in using low cost, commercially available materials for the adsorption of heavy metals. Diatomite is a siliceous sedimentary rock having an amorphous form of silica (SiO2. nH2O) containing a small amount of microcrystalline material. It has unique combination of physical and chemical properties such as high porosity, high permeability, small particle size, large surface area, and low thermal conductivity. In addition, it is available in Turkey and in various locations around the world. Therefore, diatomite has been successfully used as adsorbent for the removal of heavy metals. The aim of the study is to investigate the adsorption properties of diatomite. The equilibrium adsorption data were applied to the Langmuir, Freundlich and Dubinin-Radushkevic (D-R) isotherm models. Adsorption experiments were performed under batch process, using Pb (II) initial concentration, pH of solution and contact time as variables. The results demonstrated that the adsorption of Pb (II) was strongly dependent on pH of solution. The effect of pH on adsorption of Pb(II) on diatomite was conducted by varying pH from 2 to 12 at 20 oC. In the pH range of 2.0-4.0, the adsorption percentage increases slightly as the pH increasing. At pH>4, the adsorption percentage decreases with increasing pH because hydrolysis product and the precipitation begin to play an important role in the sorption of Pb (II). At pH4, the maximum adsorption

  15. Data of furfural adsorption on nano zero valent iron (NZVI) synthesized from Nettle extract.

    PubMed

    Fazlzadeh, Mehdi; Ansarizadeh, Mohammad; Leili, Mostafa

    2018-02-01

    Among various water and wastewater treatment methods, adsorption techniques are widely used to remove certain classes of pollutants due to its unique features. Thus, the aim of this data article is to synthesize zero valent iron nanoparticles (NZVI) from Nettle leaf extract by green synthesis method as an environmentally friendly technique, and to evaluate it's efficiency in the removal of furfural from aqueous solutions. The data of possible adsorption mechanism and isotherm of furfural on the synthesized adsorbent are depicted in this data article. The data acquired showed that the adsorption trend follows the pseudo-second order kinetic model and that the Langmuir isotherm was suitable for correlation of equilibrium data with the maximum adsorption capacity of 454.4 mg/g. The information of initial furfural concentration, pH, adsorbent dosage and contact time effects on the removal efficiency are presented. Considering the findings data, the developed nanoparticle from Nettle leaf extract, as a low cost adsorbent, could be considered as promising adsorbent for furfural and probably similar organic pollutants removal from aqueous solutions.

  16. Comprehensive Adsorption Studies of Doxycycline and Ciprofloxacin Antibiotics by Biochars Prepared at Different Temperatures

    PubMed Central

    Zeng, Zhi-wei; Tan, Xiao-fei; Liu, Yun-guo; Tian, Si-rong; Zeng, Guang-ming; Jiang, Lu-hua; Liu, Shao-bo; Li, Jiang; Liu, Ni; Yin, Zhi-hong

    2018-01-01

    This paper comparatively investigated the removal efficiency and mechanisms of rice straw biochars prepared under three pyrolytic temperatures for two kinds of tetracycline and quinolone antibiotics (doxycycline and ciprofloxacin). The influencing factors of antibiotic adsorption (including biochar dosage, pH, background electrolytes, humic acid, initial antibiotics concentration, contact time, and temperature) were comprehensively studied. The results suggest that biochars produced at high-temperature [i.e., 700°C (BC700)], have higher adsorption capacity for the two antibiotics than low-temperature (i.e., 300–500°C) biochars (BC300 and BC500). Higher surface area gives rise to greater volume of micropores and mesopores, and higher graphitic surfaces of the BC700 contributed to its higher functionality. The maximum adsorption capacity was found to be in the following order: DOX > CIP. The π-π EDA interaction and hydrogen bonding might be the predominant adsorption mechanisms. Findings in this study highlight the important roles of high-temperature biochars in controlling the contamination of tetracycline and quinolone antibiotics in the environment. PMID:29637067

  17. Comprehensive adsorption studies of doxycycline and ciprofloxacin antibiotics by biochars prepared at different temperatures

    NASA Astrophysics Data System (ADS)

    Zeng, Zhi-wei; Tan, Xiao-fei; Liu, Yun-guo; Tian, Si-rong; Zeng, Guang-ming; Jiang, Lu-hua; Liu, Shao-bo; Li, Jiang; Liu, Ni; Yin, Zhi-hong

    2018-03-01

    This paper comparatively investigated the removal efficiency and mechanisms of rice straw biochars prepared under three pyrolytic temperatures for two kinds of tetracycline and quinolone antibiotics (doxycycline and ciprofloxacin). The influencing factors of antibiotic adsorption (including biochar dosage, pH, background electrolytes, humic acid, initial antibiotics concentration, contact time, and temperature) were comprehensively studied. The results suggest that biochars produced at high-temperature (i.e., 700°C (BC700)), have higher adsorption capacity for the two antibiotics than low-temperature (i.e., 300-500°C) biochars (BC300 and BC500). Higher surface area gives rise to greater volume of micropores and mesopores, and higher graphitic surfaces of the BC700 contributed to its higher functionality. The maximum adsorption capacity was found to be in the following order: DOX > CIP. The π-π EDA interaction and hydrogen bonding might be the predominant adsorption mechanisms. Findings in this study highlight the important roles of high-temperature biochars in controlling the contamination of tetracycline and quinolone antibiotics in the environment.

  18. Adsorption of cadmium by biochar produced from pyrolysis of corn stalk in aqueous solution.

    PubMed

    Ma, Fengfeng; Zhao, Baowei; Diao, Jingru

    2016-09-01

    The purpose of this work is to investigate adsorption characteristic of corn stalk (CS) biochar for removal of cadmium ions (Cd 2+ ) from aqueous solution. Batch adsorption experiments were carried out to evaluate the effects of pH value of solution, adsorbent particle size, adsorbent dosage, and ionic strength of solution on the adsorption of Cd 2+ onto biochar that was pyrolytically produced from CS at 300 °C. The results showed that the initial pH value of solution played an important role in adsorption. The adsorptive amount of Cd 2+ onto the biochar decreased with increasing the adsorbent dosage, adsorbent particle size, and ionic strength, while it increased with increasing the initial pH value of solution and temperature. Cd 2+ was removed efficiently and quickly from aqueous solutions by the biochar with a maximum capacity of 33.94 mg/g. The adsorption process was well described by the pseudo-second-order kinetic model with the correlation coefficients greater than 0.986. The adsorption isotherm could be well fitted by the Langmuir model. The thermodynamic studies showed that the adsorption of Cd 2+ onto the biochar was a spontaneous and exothermic process. The results indicate that CS biochar can be considered as an efficient adsorbent.

  19. Statistical distribution of time to crack initiation and initial crack size using service data

    NASA Technical Reports Server (NTRS)

    Heller, R. A.; Yang, J. N.

    1977-01-01

    Crack growth inspection data gathered during the service life of the C-130 Hercules airplane were used in conjunction with a crack propagation rule to estimate the distribution of crack initiation times and of initial crack sizes. A Bayesian statistical approach was used to calculate the fraction of undetected initiation times as a function of the inspection time and the reliability of the inspection procedure used.

  20. Gas-phase formaldehyde adsorption isotherm studies on activated carbon: correlations of adsorption capacity to surface functional group density.

    PubMed

    Carter, Ellison M; Katz, Lynn E; Speitel, Gerald E; Ramirez, David

    2011-08-01

    Formaldehyde (HCHO) adsorption isotherms were developed for the first time on three activated carbons representing one activated carbon fiber (ACF) cloth, one all-purpose granular activated carbon (GAC), and one GAC commercially promoted for gas-phase HCHO removal. The three activated carbons were evaluated for HCHO removal in the low-ppm(v) range and for water vapor adsorption from relative pressures of 0.1-0.9 at 26 °C where, according to the IUPAC isotherm classification system, the adsorption isotherms observed exhibited Type V behavior. A Type V adsorption isotherm model recently proposed by Qi and LeVan (Q-L) was selected to model the observed adsorption behavior because it reduces to a finite, nonzero limit at low partial pressures and it describes the entire range of adsorption considered in this study. The Q-L model was applied to a polar organic adsorbate to fit HCHO adsorption isotherms for the three activated carbons. The physical and chemical characteristics of the activated carbon surfaces were characterized using nitrogen adsorption isotherms, X-ray photoelectron spectroscopy (XPS), and Boehm titrations. At low concentrations, HCHO adsorption capacity was most strongly related to the density of basic surface functional groups (SFGs), while water vapor adsorption was most strongly influenced by the density of acidic SFGs.

  1. Mechanism and kinetics of uranium adsorption onto soil around coal-fired power plant

    NASA Astrophysics Data System (ADS)

    Yasim, Nurzulaifa Shaheera Erne Mohd; Ariffin, Nik Azlin Nik; Mohammed, Noradila; Ayob, Syafina

    2017-11-01

    Coal is the largest source of energy in Malaysia providing approximately 80 % of all entire power needs. The combustion of coal concentrates a high content of heavy metals and radioactive elements in the ashes and sludge. Hazardous emissions from coal combustion were deposited into the soil and most likely transported into the groundwater system. The presence of radioactive materials in the ground water system can cause a wide range of environmental impacts and adverse health effects like cancer, impairment of neurological function and cardiovascular disease. However, the soil has a natural capability in adsorption of radioactive materials. Thus, this study was evaluated the adsorption capacity of Uranium onto the soil samples collected nearby the coal-fired power plants. In the batch experiment, parameters that were set constant include pH, the amount of soil and contact time. Various initial concentrations of radionuclides elements in the range of 2 mg/L - 10 mg/L were used. The equilibrium adsorption data was analyzed by the Freundlich isotherm and Langmuir isotherms. Then, the influences of solution pH, contact time and temperature on the adsorption process were investigated. The kinetics of radioactive materials was discussed by pseudo-first-order and pseudo-second-order rate equation. Thus, the data from this study could provide information about the potentiality of soil in sorption of radioactive materials that can be leached into groundwater. Besides that, this study could also be used as baseline data for future reference in the development of adsorption modeling in the calculation of distribution coefficient.

  2. Rapid adsorption of Pb, Cu and Cd from aqueous solutions by β-cyclodextrin polymers

    NASA Astrophysics Data System (ADS)

    He, Junyong; Li, Yulian; Wang, Chengming; Zhang, Kaisheng; Lin, Dongyue; Kong, Lingtao; Liu, Jinhuai

    2017-12-01

    Removing heavy metals from aqueous solutions has drawn more and more attentions these years because of their serious global health challenge to human society. To develop an adsorbent with low-cost and high-efficiency for removal of heavy metals (HMs), β-cyclodextrin (β-CD) polymers crosslinked with rigid aromatic groups were prepared and used for lead (Pb), copper (Cu) and cadmium (Cd) removal for the first time. The negatively charged β-CD polymers with large BET surface area were suitable to be used in HMs adsorption. The adsorption process completed in 5 min was well fit by Freundlich isotherm model and pseudo-second-order model. The intraparticle diffusion model was also appropriate to describe the adsorption of Pb, Cu and Cd on β-CD polymer. The maximum of adsorption capacities at 25 °C for Pb, Cu and Cd were 196.42, 164.43 and 136.43 mg/g when the initial concentration was 200 mg/L. The HMs adsorption process on the surface of β-CD polymer was an endothermic and spontaneous process. Both of the electrostatic interaction and distribution of Pb, Cu and Cd species influenced the adsorption process at different pH values. The order of removal efficiencies in multi-component adsorption for the three metal ions were Pb > Cu > Cd. The adsorption mechanisms were H+ ions on hydroxyl groups exchanged with heavy metal ions and electrostatic interactions. This study indicated that β-CD polymers could be developed into effective adsorbents for rapid removal of heavy metals.

  3. Experimental and kinetic studies on methylene blue adsorption by coir pith carbon.

    PubMed

    Kavitha, D; Namasivayam, C

    2007-01-01

    Varying the parameters such as agitation time, dye concentration, adsorbent dose, pH and temperature carried out the potential feasibility of thermally activated coir pith carbon prepared from coconut husk for removal of methylene blue. Greater percentage of dye was removed with decrease in the initial concentration of dye and increase in amount of adsorbent used. Kinetic study showed that the adsorption of dye on coir pith carbon was a gradual process. Lagergren first-order, second-order, intra particle diffusion model and Bangham were used to fit the experimental data. Equilibrium isotherms were analysed by Langmuir, Freundlich, Dubnin-Radushkevich, and Tempkin isotherm. The adsorption capacity was found to be 5.87 mg/g by Langmuir isotherm for the particle size 250-500 microm. The equilibrium time was found to be 30 and 60 min for 10 and 20 mg/L and 100 min for 30, 40 mg/L dye concentrations, respectively. A maximum removal of 97% was obtained at natural pH 6.9 for an adsorbent dose of 100 mg/50 mL and 100% removal was obtained for an adsorbent dose of 600 mg/50 mL of 10 mg/L dye concentration. The pH effect and desorption studies suggest that chemisorption might be the major mode of the adsorption process. The change in entropy (DeltaS0) and heat of adsorption (DeltaH0) of coir pith carbon was estimated as 117.20 J/mol/K and 30.88 kJ/mol, respectively. The high negative value of change in Gibbs free energy indicates the feasible and spontaneous adsorption of methylene blue on coir pith carbon.

  4. Adsorptive Removal of Cadmium (II) from Aqueous Solution by Multi-Carboxylic-Functionalized Silica Gel: Equilibrium, Kinetics and Thermodynamics

    NASA Astrophysics Data System (ADS)

    Li, Min; Meng, Xiaojing; Yuan, Jinhai; Deng, Wenwen; Liang, Xiuke

    2018-01-01

    In the present study, the adsorption behavior of cadmium (II) ion from aqueous solution onto multi-carboxylic-functionalized silica gel (SG-MCF) has been investigated in detail by means of batch and column experiments. Batch experiments were performed to evaluate the effects of various experimental parameters such as pH value, contact time and initial concentration on adsorption capacity of cadmium (II) ion. The kinetic data were analyzed on the basis of the pseudo-first-order kinetic and the pseudo-second-order kinetic models and consequently, the pseudo-second-order kinetic can better describe the adsorption process than the pseudo-first-order kinetic model. Equilibrium isotherms for the adsorption of cadmium (II) ion were analyzed by Freundlich and Langmuir isotherm models, the results indicate that Langmuir isotherm model was found to be credible to express the data for cadmium (II) ion from aqueous solution onto the SG-MCF. Various thermodynamics parameters of the adsorption process, including free energy of adsorption (ΔG0 ), the enthalpy of adsorption (ΔH0 ) and standard entropy changes (ΔS0 ), were calculated to predict the nature of adsorption. The positive value of the enthalpy change and the negative value of free energy change indicate that the process is endothermic and spontaneous process.

  5. Arsenate adsorption mechanisms at the allophane - Water interface

    USGS Publications Warehouse

    Arai, Y.; Sparks, D.L.; Davis, J.A.

    2005-01-01

    We investigated arsenate (As(V)) reactivity and surface speciation on amorphous aluminosilicate mineral (synthetic allophane) surfaces using batch adsorption experiments, powder X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The adsorption isotherm experiments indicated that As(V) uptake increased with increasing [As(V)]0 from 50 to 1000 ??M (i.e., Langmuir type adsorption isotherm) and that the total As adsorption slightly decreased with increasing NaCl concentrations from 0.01 to 0.1 M. Arsenate adsorption was initially (0-10 h) rapid followed by a slow continuum uptake, and the adsorption processes reached the steady state after 720 h. X-ray absorption spectroscopic analyses suggest that As(V) predominantly forms bidentate binuclear surface species on aluminum octahedral structures, and these species are stable up to 11 months. Solubility calculations and powder XRD analyses indicate no evidence of crystalline AI-As(V) precipitates in the experimental systems. Overall, macroscopic and spectroscopic evidence suggest that the As(V) adsorption mechanisms at the allophane-water interface are attributable to ligand exchange reactions between As(V) and surface-coordinated water molecules and hydroxyl and silicate ions. The research findings imply that dissolved tetrahedral oxyanions (e.g., H2PO42- and H2AsO42-) are readily retained on amorphous aluminosilicate minerals in aquifer and soils at near neutral pH. The innersphere adsorption mechanisms might be important in controlling dissolved arsenate and phosphate in amorphous aluminosilicate-rich low-temperature geochemical environments. ?? 2005 American Chemical Society.

  6. Adsorption of C.I. Natural Red 4 onto Spongin Skeleton of Marine Demosponge

    PubMed Central

    Norman, Małgorzata; Bartczak, Przemysław; Zdarta, Jakub; Tylus, Włodzimierz; Szatkowski, Tomasz; Stelling, Allison L.; Ehrlich, Hermann; Jesionowski, Teofil

    2014-01-01

    C.I. Natural Red 4 dye, also known as carmine or cochineal, was adsorbed onto the surface of spongin-based fibrous skeleton of Hippospongia communis marine demosponge for the first time. The influence of the initial concentration of dye, the contact time, and the pH of the solution on the adsorption process was investigated. The results presented here confirm the effectiveness of the proposed method for developing a novel dye/biopolymer hybrid material. The kinetics of the adsorption of carmine onto a marine sponge were also determined. The experimental data correspond directly to a pseudo-second-order model for adsorption kinetics (r2 = 0.979–0.999). The hybrid product was subjected to various types of analysis (FT-IR, Raman, 13C CP/MAS NMR, XPS) to investigate the nature of the interactions between the spongin (adsorbent) and the dye (the adsorbate). The dominant interactions between the dye and spongin were found to be hydrogen bonds and electrostatic effects. Combining the dye with a spongin support resulted with a novel hybrid material that is potentially attractive for bioactive applications and drug delivery systems. PMID:28787926

  7. Radiation induced emulsion graft polymerization of 4-vinylpyridine onto PE/PP nonwoven fabric for As(V) adsorption

    NASA Astrophysics Data System (ADS)

    Akkaş Kavaklı, Pınar; Kavaklı, Cengiz; Seko, Noriaki; Tamada, Masao; Güven, Olgun

    2016-10-01

    A novel nonwoven fabric adsorbent having 4-vinylpyridine functional groups was prepared by using radiation-induced emulsion graft polymerization method and grafting 4-vinylpyridine monomer onto a polyethylene-coated polypropylene nonwoven fabric (NWF) in aqueous emulsion solution. The grafting conditions of the 4-vinylpyridine monomer onto the NWF were optimised and 150% Dg VP-g-NWF was prepared using 30 kGy pre-irradiation dose, 5% VP monomer concentration and 0.5% (w/w) Tween 20 in aqueous emulsion. Grafted 4-vinylpyridine chains on the NWF were then quaternized for the preparation of QVP-g-NWF adsorbent. All fabric structures were characterized by using Fourier-transform infrared spectrometer, x-ray photoelectron spectrometer and scanning electron microscope. QVP-g-NWF adsorbent was used in batch adsorption experiments for As(V) ions by studying the pH, contact time, and initial As(V) ion concentration parameters. Results showed that QVP-g-NWF adsorbent has significant As(V) adsorption and experimental As(V) adsorption capacity was 98.04 mg As(V)/g polymer from 500 mg/L initial As(V) concentration at pH 7.00.

  8. Comparison of cadmium adsorption onto chitosan and epichlorohydrin crosslinked chitosan/eggshell composite

    NASA Astrophysics Data System (ADS)

    Rahmi; Marlina; Nisfayati

    2018-05-01

    The use of chitosan and epichlorohydrin crosslinked chitosan/eggshell composite for cadmium adsorption from water were investigated. The factors affecting adsorption such as pH and contact time were considered. The results showed that the optimum pH of adsorption was pH = 6.0 and the equilibrium time of adsorption was 40 min. The adsorption isotherm of Cd ions onto chitosan and composite were well fitted to Langmuir equation. The maximum adsorption capacity (fitting by Langmuir model) of chitosan and composite were 1.008 and 11.7647 mg/g, respectively. Adsorption performance of composite after regeneration was better than chitosan.

  9. The adsorption of HCl on volcanic ash

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Xochilt; Schiavi, Federica; Keppler, Hans

    2016-03-01

    data provided here, the gas compositions in equilibrium with the ash surfaces can be calculated. In particular, for dacitic composition, the molar ratio of S/Cl adsorbed to the ash surface is related to the molar S/Cl ratio in the gas phase according to the equation ln ⁡(S / Cl) adsorbed = 2855T-1 + 0.28 ln ⁡(S / Cl) gas - 11.14. Our data also show that adsorption on ash will significantly reduce the fraction of HCl reaching the stratosphere, only if the initial HCl content in the volcanic gas is low (<1 mol%). For higher initial HCl concentrations, adsorption on ash has only a minor effect. While HCl scavenging by hydrometeors may remove a considerable fraction of HCl from the eruption column, recent models suggest that this process is much less efficient than previously thought. Our experimental data therefore support the idea that the HCl loading from major explosive eruptions may indeed cause severe depletions of stratospheric ozone.

  10. Adsorptive amputation of hazardous azo dye Congo red from wastewater: a critical review.

    PubMed

    Raval, Nirav P; Shah, Prapti U; Shah, Nisha K

    2016-08-01

    Increasing amount of dyes in an ecosystem has propelled the search of various methods for dye removal. Amongst all the methods, adsorption occupies a prominent place in dye removal. Keeping this in mind, many adsorbents used for the removal of hazardous anionic azo dye Congo red (CR) from aqueous medium were reviewed by the authors. The main objectives behind this review article are to assemble the information on scattered adsorbents and enlighten the wide range of potentially effective adsorbents for CR removal. Thus, CR sorption by various adsorbents such as activated carbon, non-conventional low-cost materials, nanomaterials, composites and nanocomposites are surveyed and critically reviewed as well as their sorption capacities are also compared. This review also explores the grey areas of the adsorption performance of various adsorbents with reference to the effects of pH, contact time, initial dye concentration and adsorbent dosage. The equilibrium adsorption isotherm, kinetic and thermodynamic data of different adsorbents used for CR removal were also analysed. It is evident from a literature survey of more than 290 published papers that nanoparticle and nanocomposite adsorbents have demonstrated outstanding adsorption capabilities for CR. Graphical abstract ᅟ.

  11. Modeling of fixed-bed column studies for the adsorption of cadmium onto novel polymer-clay composite adsorbent.

    PubMed

    Unuabonah, Emmanuel I; Olu-Owolabi, Bamidele I; Fasuyi, Esther I; Adebowale, Kayode O

    2010-07-15

    Kaolinite clay was treated with polyvinyl alcohol to produce a novel water-stable composite called polymer-clay composite adsorbent. The modified adsorbent was found to have a maximum adsorption capacity of 20,400+/-13 mg/L (1236 mg/g) and a maximum adsorption rate constant of approximately = 7.45x10(-3)+/-0.0002 L/(min mg) at 50% breakthrough. Increase in bed height increased both the breakpoint and exhaustion point of the polymer-clay composite adsorbent. The time for the movement of the Mass Transfer Zone (delta) down the column was found to increase with increasing bed height. The presence of preadsorbed electrolyte and regeneration were found to reduce this time. Increased initial Cd(2+) concentration, presence of preadsorbed electrolyte, and regeneration of polymer-clay composite adsorbent reduced the volume of effluent treated. Premodification of polymer-clay composite adsorbent with Ca- and Na-electrolytes reduced the rate of adsorption of Cd(2+) onto polymer-clay composite and lowered the breakthrough time of the adsorbent. Regeneration and re-adsorption studies on the polymer-clay composite adsorbent presented a decrease in the bed volume treated at both the breakpoint and exhaustion points of the regenerated bed. Experimental data were observed to show stronger fits to the Bed Depth Service Time (BDST) model than the Thomas model. 2010 Elsevier B.V. All rights reserved.

  12. Experimental design based response surface methodology optimization of ultrasonic assisted adsorption of safaranin O by tin sulfide nanoparticle loaded on activated carbon.

    PubMed

    Roosta, M; Ghaedi, M; Daneshfar, A; Sahraei, R

    2014-03-25

    In this research, the adsorption rate of safranine O (SO) onto tin sulfide nanoparticle loaded on activated carbon (SnS-NPAC) was accelerated by the ultrasound. SnS-NP-AC was characterized by different techniques such as SEM, XRD and UV-Vis measurements. The present results confirm that the ultrasound assisted adsorption method has remarkable ability to improve the adsorption efficiency. The influence of parameters such as the sonication time, adsorbent dosage, pH and initial SO concentration was examined and evaluated by central composite design (CCD) combined with response surface methodology (RSM) and desirability function (DF). Conducting adsorption experiments at optimal conditions set as 4 min of sonication time, 0.024 g of adsorbent, pH 7 and 18 mg L(-1) SO make admit to achieve high removal percentage (98%) and high adsorption capacity (50.25 mg g(-)(1)). A good agreement between experimental and predicted data in this study was observed. The experimental equilibrium data fitting to Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models show that the Langmuir model is a good and suitable model for evaluation and the actual behavior of adsorption. Kinetic evaluation of experimental data showed that the adsorption processes followed well pseudo-second-order and intraparticle diffusion models. Copyright © 2013. Published by Elsevier B.V.

  13. Experimental design based response surface methodology optimization of ultrasonic assisted adsorption of safaranin O by tin sulfide nanoparticle loaded on activated carbon

    NASA Astrophysics Data System (ADS)

    Roosta, M.; Ghaedi, M.; Daneshfar, A.; Sahraei, R.

    2014-03-01

    In this research, the adsorption rate of safranine O (SO) onto tin sulfide nanoparticle loaded on activated carbon (SnS-NPAC) was accelerated by the ultrasound. SnS-NP-AC was characterized by different techniques such as SEM, XRD and UV-Vis measurements. The present results confirm that the ultrasound assisted adsorption method has remarkable ability to improve the adsorption efficiency. The influence of parameters such as the sonication time, adsorbent dosage, pH and initial SO concentration was examined and evaluated by central composite design (CCD) combined with response surface methodology (RSM) and desirability function (DF). Conducting adsorption experiments at optimal conditions set as 4 min of sonication time, 0.024 g of adsorbent, pH 7 and 18 mg L-1 SO make admit to achieve high removal percentage (98%) and high adsorption capacity (50.25 mg g-1). A good agreement between experimental and predicted data in this study was observed. The experimental equilibrium data fitting to Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models show that the Langmuir model is a good and suitable model for evaluation and the actual behavior of adsorption. Kinetic evaluation of experimental data showed that the adsorption processes followed well pseudo-second-order and intraparticle diffusion models.

  14. Adsorption behavior of plasmid DNA onto perfusion chromatographic matrix.

    PubMed

    Limonta, Miladys; Zumalacárregui, Lourdes; Soler, Dayana

    2012-05-01

    Anion exchange chromatography is the most popular chromatographic method for plasmid separation. POROS RI 50 is a perfusion chromatographic support which is a reversed phase matrix and is an alternative to conventional ones due to its mass transfer properties. The adsorption and elution of the pIDKE2 plasmid onto reversed phase POROS R1 50 was studied. Langmuir isotherm model was adjusted in order to get the maximum adsorption capacity and the dissociation constant for POROS R1 50-plasmid DNA (pDNA) system. Breakthrough curves were obtained for volumetric flows between 0.69-3.33 mL/min, given dynamic capacity up to 2.3 times higher than those reported for ionic exchange matrix used during the purification process of plasmids with similar size to that of pIDKE2. The efficiency was less than 45% for the flow conditions and initial concentration studied, which means that the support will not be operated under saturation circumstances.

  15. Molecular dynamics simulations of the adsorption of bone morphogenetic protein-2 on surfaces with medical relevance.

    PubMed

    Utesch, Tillmann; Daminelli, Grazia; Mroginski, Maria Andrea

    2011-11-01

    Bone morphogenetic protein-2 (BMP-2) plays a crucial role in osteoblast differentiation and proliferation. Its effective therapeutic use for ectopic bone and cartilage regeneration depends, among other factors, on the interaction with the carrier at the implant site. In this study, we used classical molecular dynamics (MD) and a hybrid approach of steered molecular dynamics (SMD) combined with MD simulations to investigate the initial stages of the adsorption of BMP-2 when approaching two implant surfaces, hydrophobic graphite and hydrophilic titanium dioxide rutile. Surface adsorption was evaluated for six different orientations of the protein, two end-on and four side-on, in explicit water environment. On graphite, we observed a weak but stable adsorption. Depending on the initial orientation, hydrophobic patches as well as flexible loops of the protein were involved in the interaction with graphite. On the contrary, BMP-2 adsorbed only loosely to hydrophilic titanium dioxide. Despite a favorable interaction energy between protein and the TiO(2) surface, the rapid formation of a two-layer water structure prevented the direct interaction between protein and titanium dioxide. The first water adlayer had a strong repulsive effect on the protein, while the second attracted the protein toward the surface. For both surfaces, hydrophobic graphite and hydrophilic titanium dioxide, denaturation of BMP-2 induced by adsorption was not observed on the nanosecond time scale.

  16. Adsorption and desorption characteristics of arsenic onto ceria nanoparticles

    PubMed Central

    2012-01-01

    The rapid increase in the use of engineered nanoparticles [ENPs] has resulted in an increasing concern over the potential impacts of ENPs on the environmental and human health. ENPs tend to adsorb a large variety of toxic chemicals when they are emitted into the environment, which may enhance the toxicity of ENPs and/or adsorbed chemicals. The study was aimed to investigate the adsorption and desorption behaviors of arsenic on ceria NPs in aqueous solution using batch technique. Results show that the adsorption behavior of arsenic on ceria NPs was strongly dependent on pH and independent of ionic strength, indicating that the electrostatic effect on the adsorption of these elements was relatively not important compared to surface chemical reactions. The adsorption isotherms fitted very well to both the Langmuir and Freundlich models. The thermodynamic parameters (ΔH0, ΔS0, and ΔG0) for the adsorption of arsenic were determined at three different temperatures of 283, 303, and 323 K. The adsorption reaction was endothermic, and the process of adsorption was favored at high temperature. The desorption data showed that desorption hysteresis occurred at the initial concentration studied. High adsorption capacity of arsenic on ceria NPs suggests that the synergistic effects of ceria NPs and arsenic on the environmental systems may exist when they are released into the environment. PMID:22269298

  17. Management of agricultural waste for removal of heavy metals from aqueous solution: adsorption behaviors, adsorption mechanisms, environmental protection, and techno-economic analysis.

    PubMed

    Elhafez, S E Abd; Hamad, H A; Zaatout, A A; Malash, G F

    2017-01-01

    In the last decades, Egypt has been suffering from the phenomenon of black cloud resulting from burning rice husk and increasing the demand for water leading to the water crisis. An alternative, low-value and surplus agricultural byproduct (rice husk, RH) has an enormous potential for the removal of Cu(II) ions from water. The present study focuses on the chance of the use of rice husk as a bio-adsorbent without any chemical treatment instead of burning it and soiling the environment. The elemental, structural, morphological, surface functional, thermal, and textural characteristics of RH are determined by XRF, XRD, SEM, FT-IR, TGA, and BET surface area, respectively, and contributed to the understanding of the adsorption mechanism of Cu(II) ions in aqueous solution. Also, the performance analysis, adsorption mechanism, influencing factors, favorable conditions, etc. are discussed in this article. The results obtained from optimization by batch mode are achieved under the following conditions: initial concentration, 150 ppm; amount of rice husk, 1 g; average particle size, 0.25 mm; temperature, 25 °C; pH, 4; agitation rate, 180 rpm; and contact time, 60 min. RH exhibits a high degree of selectivity for Cu(II) adsorption. The adsorption isotherm is fitted well with Langmuir and Freundlich models with R 2 0.998 and 0.997, respectively. The adsorption is well governed by the pseudo-second-order kinetics. It is observed that the rate of adsorption improves with decreasing temperature, and the process is exothermic and non-spontaneous. Particular attention has being paid to factors as production processes, fixed/operational cost, production cost, and profit. The techno-economical analysis is presented in this study that provides precise demands on capital for a fixed investment, provisions for operational capital, and finally provisions for revenue. The social, economical, and environmental benefits by industrial point of view using low-cost adsorbent are also

  18. Adsorption of Roxarsone onto Drinking Water Treatment Residuals: Preliminary Studies

    NASA Astrophysics Data System (ADS)

    Salazar, J.; Sarkar, D.; Datta, R.; Sharma, S.

    2006-05-01

    Roxarsone (3-nitro-4-hydroxyphenyl-arsonic acid) is an organo-arsenical compound, commonly used as a feed additive in the broiler poultry industry to control coccidial intestinal parasites. Roxarsone is not toxic to the birds not only because of the low dose, and also because it most likely does not convert to toxic inorganic arsenic (As) in their systems. However, upon excretion, roxarsone may undergo transformation to inorganic As, posing a serious risk of contaminating the agricultural land and water bodies via surface runoff or leaching. The use of poultry litter as fertilizer results in As accumulation rates of up to 50 metric tons per year in agricultural lands. The immediate challenge, as identified by the various regulatory bodies in recent years is to develop an efficient, yet cost-effective and environmentally sound approach to cleaning up such As- contaminated soils. Recent studies conducted by our group have suggested that the drinking water treatment residuals (WTRs) can effectively retain As, thereby decreasing its mobility in the environment. The WTRs are byproducts of drinking water treatment processes and are typically composed of amorphous Fe/Al oxides, activated C and cationic polymers. They can be obtained free-of-cost from water treatment plants. It is well demonstrated that the environmental mobility of As is controlled by adsorption/desorption reactions onto mineral surfaces. Hence, knowledge of adsorption and desorption of As onto the WTRs is of environmental relevance. The reported study examined the adsorption and desorption characteristics of As using two types of WTRs, namely the Fe-WTRs (byproduct of Fe salt treatment), and the Al-WTRs (byproduct of Al salt treatment). All adsorption experiments were carried out in batch and As retention on the WTRs was investigated as a function of solid/solution ratio (1:5, 1:10, 1:25 and 1:50), equilibration time (10 min - 48 hr), pH (2 - 10) and initial As load (100, 500, 1000 and 2000 mg As/L). The

  19. Preparation of highly ordered cubic NaA zeolite from halloysite mineral for adsorption of ammonium ions.

    PubMed

    Zhao, Yafei; Zhang, Bing; Zhang, Xiang; Wang, Jinhua; Liu, Jindun; Chen, Rongfeng

    2010-06-15

    Well-ordered cubic NaA zeolite was first synthesized using natural halloysite mineral with nanotubular structure as source material by hydro-thermal method. SEM and HRTEM images indicate that the synthesized NaA zeolite is cubic-shaped crystal with planar surface, well-defined edges and symmetrical and uniform pore channels. The adsorption behavior of ammonium ions (NH(4)(+)) from aqueous solution onto NaA zeolite was investigated as a function of parameters such as equilibrium time, pH, initial NH(4)(+) concentration, temperature and competitive cations. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. A maximum adsorption capacity of 44.3 mg g(-1) of NH(4)(+) was achieved. The regeneration and reusable ability of this adsorbent was evaluated, and the results indicated that the recovered adsorbent could be used again for NH(4)(+) removal with nearly constant adsorption capacity. Thermodynamic parameters such as change in free energy (DeltaG(0)), enthalpy (DeltaH(0)) and entropy (DeltaS(0)) were also determined, which indicated that the adsorption was a spontaneous and exothermic process at ambient conditions. Compared with other adsorbents, the as-synthesized NaA zeolite displays a faster adsorption rate and higher adsorption capacity, which implies potential application for removing NH(4)(+) pollutants from wastewaters. Copyright 2010 Elsevier B.V. All rights reserved.

  20. [Effect of SO2 volume fraction in flue gas on the adsorption behaviors adsorbed by ZL50 activated carbon and kinetic analysis].

    PubMed

    Gao, Ji-xian; Wang, Tie-feng; Wang, Jin-fu

    2010-05-01

    The influence of SO2 dynamic adsorption behaviors using ZL50 activated carbon for flue gas desulphurization and denitrification under different SO2 volume fraction was investigated experimentally, and the kinetic analysis was conducted by kinetic models. With the increase of SO2 volume fraction in flue gas, the SO2 removal ratio and the activity ratio of ZL50 activated carbon decreased, respectively, and SO2 adsorption rate and capacity increased correspondingly. The calculated results indicate that Bangham model has the best prediction effect, the chemisorption processes of SO2 was significantly affected by catalytic oxidative reaction. The adsorption rate constant of Lagergren's pseudo first order model increased with the increase of inlet SO, volume fraction, which indicated that catalytic oxidative reaction of SO2 adsorbed by ZL50 activated carbon may be the rate controlling step in earlier adsorption stage. The Lagergren's and Bangham's initial adsorption rate were deduced and defined, respectively. The Ho's and Elovich's initial adsorption rate were also deduced in this paper. The Bangham's initial adsorption rate values were defined in good agreement with those of experiments. The defined Bangham's adsorptive reaction kinetic model can describe the SO2 dynamic adsorption rate well. The studied results indicated that the SO2 partial order of initial reaction rate was one or adjacent to one, while the O2 and water vapor partial order of initial reaction rate were constants ranging from 0.15-0.20 and 0.45-0.50, respectively.

  1. Adsorption of arsenic by activated carbon, calcium alginate and their composite beads.

    PubMed

    Hassan, A F; Abdel-Mohsen, A M; Elhadidy, H

    2014-07-01

    The present investigation deals with preparation of three different adsorbent materials namely; potassium hydroxide activated carbon based apricot stone (C), calcium alginate beads (G) and calcium alginate/activated carbon composite beads (GC) were used for the removal of arsenic. The prepared adsorbent materials were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), N2-adsorption at -196°C and point of zero charge. From the obtained results, it was found that the porosity, surface area and total pore volume of the adsorbent material C>GC>G respectively, however, the G adsorbent has more acidic function group than the other adsorbents. The influence of pH, time, temperature and initial concentration of arsenic(V) were studied and optimized. GC exhibits the maximum As(V) adsorption (66.7mg/g at 30°C). The adsorption of arsenic ions was observed to follow pseudo-second order mechanism as well as the thermodynamic parameters confirm also the endothermic spontaneous and a physisorption process. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Gd-DTPA Adsorption on Chitosan/Magnetite Nanocomposites

    NASA Astrophysics Data System (ADS)

    Pylypchuk, Ie. V.; Kołodyńska, D.; Kozioł, M.; Gorbyk, P. P.

    2016-03-01

    The synthesis of the chitosan/magnetite nanocomposites is presented. Composites were prepared by co-precipitation of iron(II) and iron(III) salts by aqueous ammonia in the 0.1 % chitosan solution. It was shown that magnetite synthesis in the chitosan medium does not affect the magnetite crystal structure. The thermal analysis data showed 4.6 % of mass concentration of chitosan in the hybrid chitosan/magnetite composite. In the concentration range of initial Gd-DTPA solution up to 0.4 mmol/L, addition of chitosan to magnetite increases the adsorption capacity and affinity to Gd-DTPA complex. The Langmuir and Freundlich adsorption models were applied to describe adsorption processes. Nanocomposites were characterized by scanning electron microscopy (SEM), differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and specific surface area determination (ASAP) methods.

  3. Computation of adsorption parameters for the removal of dye from wastewater by microwave assisted sawdust: Theoretical and experimental analysis.

    PubMed

    S, Suganya; P, Senthil Kumar; A, Saravanan; P, Sundar Rajan; C, Ravikumar

    2017-03-01

    In this research, the microwave assistance has been employed for the preparation of novel material from agro/natural bio-waste i.e. sawdust, for the effective removal of methylene blue (MB) dye from aqueous solution. The characterization of the newly prepared microwave assisted sawdust (MASD) material was performed by using FTIR, SEM and XRD analyses. In order to obtain the maximum removal of MB dye from wastewater, the adsorption experimental parameters such as initial dye concentration, contact time, solution pH and adsorbent dosage were optimized by trial and error approach. The obtained experimental results were applied to the different theoretical models to predict the system behaviour. The optimum conditions for the maximum removal MB dye from aqueous solution for an initial MB dye concentration of 25mg/L was calculated as: adsorbent dose of 3g/L, contact time of 90min, solution pH of 7.0 and at the temperature of 30°C. Freundlich and pseudo-second order models was best obeyed with the studied experimental data. Langmuir maximum monolayer adsorption capacity of MASD for MB dye removal was calculated as 58.14mg of MB dye/g of MASD. Adsorption diffusion model stated that the present adsorption system was controlled by intraparticle diffusion model. The obtained results proposed that, novel MASD was considered to be an effective and low-cost adsorbent material for the removal of dye from wastewater. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Highly selective adsorption of hydroquinone by hydroxyethyl cellulose functionalized with magnetic/ionic liquid.

    PubMed

    Ding, Chaofan; Li, Yue; Wang, Yanhui; Li, Jianbo; Sun, Yuanling; Lin, Yanna; Sun, Weiyan; Luo, Chuannan

    2018-02-01

    Magnetic hydroxyethyl cellulose/ionic liquid (MHEC/IL) materials were fabricated through a facile and fast process and their application as excellent adsorbents for hydroquinone was also demonstrated. The thermal stability, chemical structure and magnetic property of the MHEC/IL were characterized by the Scanning electron microscope (SEM), Transmission Electron Microscope (TEM), Fourier transform infrared spectrometer (FT-IR) and X-ray diffraction (XRD), respectively. The adsorbents were used for the removal of hydroquinone from simulated wastewater with a fast solid-liquid separation in the presence of external magnetic field. The influence of various analytical parameters on the adsorption of hydroquinone such as pH, contact time and initial ion concentration were studied in detail. The results showed that the maximum adsorption capacity was 335.68mgg -1 , observed at pH 5 and temperature 30°C. Equilibrium adsorption was achieved within 30min. The kinetic data, obtained at the optimum pH 5, could be fitted with a pseudo-second order equation. Adsorption process could be well described by Freundlich adsorption isotherms. The obtained results indicated that the impregnation of the room temperature IL significantly enhances the removal efficiency of hydroquinone. The MHEC/IL may be suitable materials in phenols pollution cleanup if they are synthesized in largescale and at low price in near future. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Statistical mechanical models for dissociative adsorption of O2 on metal(100) surfaces with blocking, steering, and funneling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Evans, James W.; Liu, Da-Jiang

    We develop statistical mechanical models amenable to analytic treatment for the dissociative adsorption of O2 at hollow sites on fcc(100) metal surfaces. The models incorporate exclusion of nearest-neighbor pairs of adsorbed O. However, corresponding simple site-blocking models, where adsorption requires a large ensemble of available sites, exhibit an anomalously fast initial decrease in sticking. Thus, in addition to blocking, our models also incorporate more facile adsorption via orientational steering and funneling dynamics (features supported by ab initio Molecular Dynamics studies). Behavior for equilibrated adlayers is distinct from those with finite adspecies mobility. We focus on the low-temperature limited-mobility regime wheremore » analysis of the associated master equations readily produces exact results for both short- and long-time behavior. Kinetic Monte Carlo simulation is also utilized to provide a more complete picture of behavior. These models capture both the initial decrease and the saturation of the experimentally observed sticking versus coverage, as well as features of non-equilibrium adlayer ordering as assessed by surface-sensitive diffraction.« less

  6. Adsorption of Toluene and Paraxylene from Aqueous Solution Using Pure and Iron Oxide Impregnated Carbon Nanotubes: Kinetics and Isotherms Study

    PubMed Central

    Abbas, Aamir; Ihsanullah; Al-Baghli, Nadhir A. H.

    2017-01-01

    Multiwall carbon nanotubes (CNTs) and iron oxide impregnated carbon nanotubes (CNTs-iron oxide) were investigated for the adsorption of hazardous toluene and paraxylene (p-xylene) from aqueous solution. Pure CNTs were impregnated with iron oxides nanoparticles using wet impregnation technique. Various characterization techniques including thermogravimetric analysis, scanning electron microscopy, elemental dispersion spectroscopy, X-ray diffraction, and nitrogen adsorption analysis were used to study the thermal degradation, surface morphology, purity, and surface area of the materials. Batch adsorption experiments show that iron oxide impregnated CNTs have higher degree of removal of p-xylene (i.e., 90%) compared with toluene (i.e., 70%), for soaking time 2 h, with pollutant initial concentration 100 ppm, at pH 6 and shaking speed of 200 rpm at 25°C. Pseudo-second-order model provides better fitting for the toluene and p-xylene adsorption. Langmuir and Freundlich isotherm models demonstrate good fitting for the adsorption data of toluene and p-xylene. PMID:28386208

  7. Adsorption of (99m)Tc-radiopharmaceuticals onto injection vials and syringes.

    PubMed

    Mushtaq, Ahmad; Ur Rehman, Taj; Safdar Mansur, Muhammad; Jehangir, Mustanser

    2008-06-01

    Many groups have reported the adsorption or retention of (99m)Tc-radiopharmaceuticals on injection vials and disposable plastic syringes. Such an enormously high loss of radioactivity would result in poor images, radiation exposure, waste, and economic burdens. We therefore decided to investigate the extent of adsorption or retention of several (99m)Tc-radiopharmaceuticals on injection vials, rubber stoppers, and plastic syringes. These radiopharmaceuticals are produced as lyophilized kits in our department and supplied to various hospitals practicing nuclear medicine in Pakistan. A vial containing lyophilized material was reconstituted with 3 mL of freshly eluted Na(99m)TcO(4). A 1-mL aliquot of the resulting solution was withdrawn into a syringe at 0.25, 0.5, 1, 3, and 5 h after preparation. All preparations were stored at room temperature ( approximately 22 degrees C). After each withdrawal, the vial was reweighed and the activity remaining in the vial was measured using a radioisotope calibrator. The sample was reinjected into the vial. From the original weight and activity of solution in the vial, the initial activity per gram was calculated. From the weight and activity remaining in the vial after withdrawal of the sample, the activity per gram of the sample was calculated. From the difference between the initial activity per gram and the activity per gram of the sample, the percentage of (99m)Tc adsorbed on the vial was calculated. All preparations were kept in the syringe for 15 min, and the activity was measured before and after the syringe was emptied. The needle and plunger of the syringe were separated, and activity in the needle and plunger was also measured. The labeling efficiency of all radiopharmaceuticals used during these studies was more than 95%. In most cases, the activity of (99m)Tc found on the rubber stopper was less than 1%. Adsorption of (99m)Tc onto vials increased gradually with storage time. Adsorption was minimal at the initial stages

  8. Adsorption preference for divalent metal ions by Lactobacillus casei JCM1134.

    PubMed

    Endo, Rin; Aoyagi, Hideki

    2018-05-09

    The removal of harmful metals from the intestinal environment can be inhibited by various ions which can interfere with the adsorption of target metal ions. Therefore, it is important to understand the ion selectivity and adsorption mechanism of the adsorbent. In this study, we estimated the adsorption properties of Lactobacillus casei JCM1134 by analyzing the correlation between its maximum adsorption level (q max ) for seven metals and their ion characteristics. Some metal ions showed altered adsorption levels by L. casei JCM1134 as culture growth time increased. Although it was impossible to identify specific adsorption components, adsorption of Sr and Ba may depend on capsular polysaccharide levels. The maximum adsorption of L. casei JCM1134 (9 h of growth in culture) for divalent metal ions was in the following order: Cu 2+  > Ba 2+  > Sr 2+  > Cd 2+  > Co 2+  > Mg 2+  > Ni 2+ . The q max showed a high positive correlation with the ionic radius. Because this tendency is similar to adsorption occurring through an ion exchange mechanism, it was inferred that an ion exchange mechanism contributed greatly to adsorption by L. casei JCM1134. Because the decrease in the amount of adsorption due to prolonged culture time was remarkable for metals with a large ion radius, it is likely that the adsorption components involved in the ion exchange mechanism decomposed over time. These results and analytical concept may be helpful for designing means to remove harmful metals from the intestinal tract.

  9. Study of the adsorption of mercury (II) on lignocellulosic materials under static and dynamic conditions.

    PubMed

    Arias Arias, Fabian E; Beneduci, Amerigo; Chidichimo, Francesco; Furia, Emilia; Straface, Salvatore

    2017-08-01

    WHO has declared mercury as one of the most dangerous pollutants for human health. Unfortunately, several cases of rivers and aquifers contaminated by mercury inevitably poses the problem on how to remediate them. Considerable efforts are being addressed to develop cost-effective methodologies, among which the use of low-cost adsorbing materials. In this paper, the adsorption performances of an alternative lignocellulosic material derived from the Spanish broom plant, are presented. This plant is widely diffused in the world and its usage for Hg(II) removal from water in real working conditions requires only minimal pretreatment steps. A thoroughly investigation on the kinetics and thermodynamics of Hg(II) adsorption on Spanish broom is presented, by using Hg(II) polluted aqueous solutions specifically prepared in order to simulate typical groundwater conditions. Several batch experiments, under static conditions, were carried out in order to evaluate the effect of pH, contact time, adsorbent dosage, initial concentration, temperature. A maximum adsorption capacity of 20 mg L -1 can be obtained at pH 5, following a pseudo second order kinetics. Moreover, adsorption experiments in dynamic conditions were carried out using Spanish broom filters. Interestingly, a systematic, unconventional double S-shape breakthrough curve was observed under different experimental conditions, revealing the occurrence of two adsorption processes with different time scales. This behavior has been fitted by a bimodal Thomas model which, unlike the single Thomas fitting, gives satisfactory results with the introduction of a new parameter related to the fraction of surface active sites involved in the adsorption processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Macroscopic and spectroscopic investigations of the adsorption of nitroaromatic compounds on graphene oxide, reduced graphene oxide, and graphene nanosheets.

    PubMed

    Chen, Xiaoxiao; Chen, Baoliang

    2015-05-19

    The surface properties and adsorption mechanisms of graphene materials are important for potential environmental applications. The adsorption of m-dinitrobenzene, nitrobenzene, and p-nitrotoluene onto graphene oxide (GO), reduced graphene oxide (RGO), and graphene (G) nanosheets was investigated using IR spectroscopy to probe the molecular interactions of graphene materials with nitroaromatic compounds (NACs). The hydrophilic GO displayed the weakest adsorption capability. The adsorption of RGO and G was significantly increased due to the recovery of hydrophobic π-conjugation carbon atoms as active sites. RGO nanosheets, which had more defect sites than did GO or G nanosheets, resulted in the highest adsorption of NACs which was 10-50 times greater than the reported adsorption of carbon nanotubes. Superior adsorption was dominated by various interaction modes including π-π electron donor-acceptor interactions between the π-electron-deficient phenyls of the NACs and the π-electron-rich matrix of the graphene nanosheets, and the charge electrostatic and polar interactions between the defect sites of graphene nanosheets and the -NO2 of the NAC. The charge transfer was initially proved by FTIR that a blue shift of asymmetric -NO2 stretching was observed with a concomitant red shift of symmetric -NO2 stretching after m-dinitrobenzene was adsorbed. The multiple interaction mechanisms of the adsorption of NAC molecule onto flat graphene nanosheets favor the adsorption, detection, and transformation of explosives.

  11. Adsorption dynamics of methyl violet onto granulated mesoporous carbon: Facile synthesis and adsorption kinetics.

    PubMed

    Kim, Yohan; Bae, Jiyeol; Park, Hosik; Suh, Jeong-Kwon; You, Young-Woo; Choi, Heechul

    2016-09-15

    A new and facile one-step synthesis method for preparing granulated mesoporous carbon (GMC) with three-dimensional spherical mesoporous symmetry is prepared to remove large molecular weight organic compounds in aqueous phase. GMC is synthesized in a single step using as-synthesized mesoporous carbon particles and organic binders through a simple and economical synthesis approach involving a simultaneous calcination and carbonization process. Characterization results obtained from SEM, XRD, as well as surface and porosity analysis indicate that the synthesized GMC has similar physical properties to those of the powdered mesoporous carbon and maintains the Brunauer-Emmett-Teller (BET) surface area and pore volume because the new synthesis method prevents the collapse of the pores during the granulation process. Batch adsorption experiments revealed GMC showed a substantial adsorption capacity (202.8 mg/g) for the removal of methyl violet as a target large molecular contaminant in aqueous phase. The mechanisms and dynamics modeling of GMC adsorption were also fully examined, which revealed that surface diffusion was rate limiting step on adsorption process of GMC. Adsorption kinetics of GMC enables 3 times faster than that of granular activated carbon in terms of surface diffusion coefficient. This is the first study, to the best of our knowledge, to synthesize GMC as an adsorbent for water purification by using facile granulation method and to investigate the adsorption kinetics and characteristics of GMC. This study introduces a new and simple method for the synthesis of GMC and reveals its adsorption characteristics for large molecular compounds in a water treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Comprehensive reuse of drinking water treatment residuals in coagulation and adsorption processes.

    PubMed

    Jung, Kyung-Won; Hwang, Min-Jin; Park, Dae-Seon; Ahn, Kyu-Hong

    2016-10-01

    While drinking water treatment residuals (DWTRs) inevitably lead to serious problems due to their huge amount of generation and limitation of landfill sites, their unique properties of containing Al or Fe contents make it possible to reuse them as a beneficial material for coagulant recovery and adsorbent. Hence, in the present study, to comprehensively handle and recycle DWTRs, coagulant recovery from DWTRs and reuse of coagulant recovered residuals (CRs) were investigated. In the first step, coagulant recovery from DWTRs was conducted using response surface methodology (RSM) for statistical optimization of independent variables (pH, solid content, and reaction time) on response variable (Al recovery). As a result, a highly acceptable Al recovery of 97.5 ± 0.4% was recorded, which corresponds to 99.5% of the predicted Al recovery. Comparison study of recovered and commercial coagulant from textile wastewater treatment indicated that recovered coagulant has reasonable potential for use in wastewater treatment, in which the performance efficiencies were 68.5 ± 2.1% COD, 97.2 ± 1.9% turbidity, and 64.3 ± 1.0% color removals at 50 mg Al/L. Subsequently, in a similar manner, RSM was also applied to optimize coagulation conditions (Al dosage, initial pH, and reaction time) for the maximization of real cotton textile wastewater treatment in terms of COD, turbidity, and color removal. Overall performance revealed that the initial pH had a remarkable effect on the removal performance compared to the effects of other independent variables. This is mainly due to the transformation of metal species form with increasing or decreasing pH conditions. Finally, a feasibility test of CRs as adsorbent for phosphate adsorption from aqueous solution was conducted. Adsorption equilibrium of phosphate at different temperatures (10-30 °C) and initial levels of pH (3-11) indicated that the main mechanisms of phosphate adsorption onto CRs are endothermic and chemical

  13. Removal of tetracycline from aqueous solution by MCM-41-zeolite A loaded nano zero valent iron: Synthesis, characteristic, adsorption performance and mechanism.

    PubMed

    Guo, Yige; Huang, Wenli; Chen, Bin; Zhao, Ying; Liu, Dongfang; Sun, Yu; Gong, Bin

    2017-10-05

    In this study, nano zero valent iron (NZVI) modified MCM-41-zeolite A (Fe-MCM-41-A) composite as a novel adsorbent was prepared by precipitation method and applied for tetracycline (TC) removal from aqueous solution. The adsorbent was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and N 2 -BET analysis. Hysteresis loops indicated that the sample has a desirable magnetic property and can be separated quickly. Adsorption studies were carried out to evaluate its potential for TC removal. Results showed that the optimal Fe-MCM-41-A dosage, initial pH and reaction time at initial TC concentration of 100mgL -1 solution are 1gL -1 , pH=5, and 60 min respectively, at which the removal efficiency of TC was 98.7%. The TC adsorption results fitted the Langmuir isotherm model very well and the adsorption process could be described by a pseudo-second-order kinetic model. A maximum TC adsorption capacity of 526.32mgg -1 was achieved. This study demonstrates that Fe-MCM-41-A is a promising and efficient material for TC adsorption from aqueous solution. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Structural changes caused by H 2 adsorption on the Si(111)7 × 7 surface

    NASA Astrophysics Data System (ADS)

    Wolff, S. H.; Wagner, S.; Gibson, J. M.; Loretto, D.; Robinson, I. K.; Bean, J. C.

    1990-12-01

    Structural changes caused by the adsorption of molecular hydrogen adsorption onto the Si(111)7 × 7 surface reconstruction are quantified using the first structure parameter refinement on transmission electron diffraction (TED) data. We find that initial adsorption of molecular hydrogen onto the Si(111)7 × 7 surface causes a preferential decrease in the occupancy of the center adatoms. Further adsorption of hydrogen results in the breaking of the dimer bonds and the removal of the corner adatoms.

  15. Preparation of chitosan/MCM-41-PAA nanocomposites and the adsorption behaviour of Hg(II) ions

    NASA Astrophysics Data System (ADS)

    Fu, Yong; Huang, Yue; Hu, Jianshe

    2018-03-01

    A novel functional hybrid mesoporous composite material (CMP) based on chitosan and MCM-41-PAA was reported and its application as an excellent adsorbent for Hg(II) ions was also investigated. Innovatively, MCM-41-PAA was prepared by using diatomite and polyacrylic acid (PAA) with integrated polymer-silica hybrid frameworks, and then CMP was fabricated by introducing MCM-41-PAA to chitosan using glutaraldehyde as a cross-linking agent. The structure and morphology of CMP were characterized by X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis, scanning electron microscopy and Brunauer-Emmett-Teller measurements. The results showed that the CMP possessed multifunctional groups such as -OH, -COOH and -NH2 with large specific surface area. Adsorption behaviour of Hg(II) ions onto CMP was fitted better by the pseudo-second-order kinetic model and the Langmuir model when the initial Hg(II) concentration, pH, adsorption temperature and time were 200 mg l-1, 4, 298 K and 120 min, respectively, as the optimum conditions. The corresponding maximum adsorption capacity could reach 164 mg g-1. According to the thermodynamic parameters determined such as free energy, enthalpy and entropy, the adsorption process of Hg(II) ions was spontaneous endothermic adsorption.

  16. Preparation of chitosan/MCM-41-PAA nanocomposites and the adsorption behaviour of Hg(II) ions

    PubMed Central

    Fu, Yong; Huang, Yue; Hu, Jianshe

    2018-01-01

    A novel functional hybrid mesoporous composite material (CMP) based on chitosan and MCM-41-PAA was reported and its application as an excellent adsorbent for Hg(II) ions was also investigated. Innovatively, MCM-41-PAA was prepared by using diatomite and polyacrylic acid (PAA) with integrated polymer–silica hybrid frameworks, and then CMP was fabricated by introducing MCM-41-PAA to chitosan using glutaraldehyde as a cross-linking agent. The structure and morphology of CMP were characterized by X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis, scanning electron microscopy and Brunauer–Emmett–Teller measurements. The results showed that the CMP possessed multifunctional groups such as –OH, –COOH and –NH2 with large specific surface area. Adsorption behaviour of Hg(II) ions onto CMP was fitted better by the pseudo-second-order kinetic model and the Langmuir model when the initial Hg(II) concentration, pH, adsorption temperature and time were 200 mg l−1, 4, 298 K and 120 min, respectively, as the optimum conditions. The corresponding maximum adsorption capacity could reach 164 mg g−1. According to the thermodynamic parameters determined such as free energy, enthalpy and entropy, the adsorption process of Hg(II) ions was spontaneous endothermic adsorption. PMID:29657793

  17. Adsorption studies of methylene blue and gentian violet on sugarcane bagasse modified with EDTA dianhydride (EDTAD) in aqueous solutions: kinetic and equilibrium aspects.

    PubMed

    Gusmão, Karla Aparecida Guimarães; Gurgel, Leandro Vinícius Alves; Melo, Tânia Márcia Sacramento; Gil, Laurent Frédéric

    2013-03-30

    In this study the adsorption of cationic dyes by modified sugarcane bagasse with EDTA dianhydride (EB) was examined using methylene blue (MB) and gentian violet (GV) as model compounds in aqueous single solutions. The synthesized adsorbent (EB) was characterized by FTIR, elemental analysis, and BET. The capacity of EB to adsorb dyes was evaluated at different contact times, pH values, and initial dye concentrations. According to the obtained results, the adsorption processes could be described by a pseudo-second-order kinetic model. The adsorption isotherms were well fitted by the Langmuir model. Maximum adsorption capacities for MB and GV on EB were found to be 202.43 and 327.83 mg/g, respectively. The free energy change during adsorption of MB and GV was found to be -22.50 and -24.21 kJ/mol, respectively, suggesting that chemisorption is the main mechanism controlling the adsorption process. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. An intrinsically shielded hydrogel for the adsorptive recovery of lysozyme.

    PubMed

    Wang, Lu; Zhang, Rongsheng; Eisenthal, Robert; Hubble, John

    2006-07-01

    The present paper addresses the selective recovery of lysozyme from egg white using CM-dextran (carboxymethyldextran)-based hydrogels containing Cibacron Blue as an affinity ligand and co-immobilized BSA intended to act as a shielding agent to reduce non-specific adsorption. Initial studies using pure lysozyme were conducted that indicated that the adsorption capacity increased with ligand density and that adsorption was well described by a Langmuir-type isotherm. The inclusion of BSA as a putative shielding agent did not decrease the adsorption capacity for lysozyme in single-adsorbate experiments. To assess the effectiveness of the shielding strategy, subsequent experiments were conducted with both defined lysozyme/ovalbumin mixtures and hen's-egg white. From these studies, the optimal operating conditions for lysozyme recovery have been determined. These include: optimal initial egg-white concentration [a 10% (v/v) solution of native egg white in the chosen buffer], affinity-ligand density (1.86 mM) and ligand-to-shielding-agent ratio (4:1). The purity of lysozyme obtained from egg white was improved from 69% with a non-shielded hydrogel to 94% with an intrinsically shielded hydrogel. Finally, the possibility of using a protein, rather than dextran-backbone-based, hydrogel was investigated. It was found that BSA could take the place of CM-dextran as the gel backbone in a simplified synthesis, producing a gel which also proved effective for lysozyme recovery with a 30% lysozyme in egg-white solution purified to approx. 92% in a single adsorption-desorption cycle.

  19. Preparation and characterization of poly(AA co PVP)/PGS composite and its application for methylene blue adsorption.

    PubMed

    Yang, Cai-xia; Lei, Lei; Zhou, Peng-xin; Zhang, Zhe; Lei, Zi-qiang

    2015-04-01

    Poly (AA co PVP)/PGS (PAPP) composite adsorbent was prepared by radical polymerization from Acrylic acid (AA), Polyvinylpyrrolidone (PVP) and Palygorskite (PGS), using N,N-methylenebisacrylamide (MBA) as cross-linker and potassium persulfate (KPS) as initiator. The PAPP was characterized with Fourier transform infrared (FT-IR), thermogravimetric analysis (TG), scanning electron microscope (SEM) and transmission electron microscopy (TEM). PAPP was used as adsorbent for the removal of methylene blue from aqueous solutions. The influences of pH, adsorption temperature and adsorption time on the adsorption properties of the composite to the dye were also investigated. Meanwhile, the adsorption rate data and adsorption equilibrium date were analyzed based on the pseudo-first-order and pseudo-second-order kinetic model, Langmuir and Freundlich isotherm models, respectively. The results indicating that the kinetic behavior better fit with the pseudo-second-order kinetic model. The maximum equilibrium adsorption capacity (q(m)) is 1815 mg/g at 289 K. The isotherm behavior can be explained by the Langmuir isotherm models. The activation energy was also evaluated for the removal of methylene blue onto PAPP. These results demonstrate that this composite material could be used as a good adsorbent for the removal of cationic dyes from wastewater. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. [Preparation of Pb2+ imprinted acrylic acid-co-styrene and analysis of its adsorption properties by FAAS].

    PubMed

    Shawket, Abliz; Abdiryim, Supahun; Wang, Ji-De; Ismayil, Nurulla

    2011-06-01

    With lead ion template, acrylic acid as functional monomer, potassium persulfate as initiator, strytrene as framework monomer, lead ion imprinted polymers (Pb(II)-IIPs) were prepared using free emulsion polymerization method. The structure and morphology of the polymers were analyzed by UV-spectra, FTIR and scanning electron microscopy. The adsorption/ desorption and selectivity for Pb2+ were investigated by flame atomic absorption spectrometry (FAAS) as the detection means. The results show that compared with non-imprinted polymers(NIPs), the Pb(II)-IIPs had higher specific adsorption properties and selective recognition ability for Pb(II). The relative selectivity coefficient of Pb(II)-IIPs for Pb(II) was 6.25, 6.18, 6.25 and 6.38 in the presence of Cd(II), Cu(II), Mn(II) and Zn(II) interferences, respectively. The absorption rate was the best at the pH of adsorbent solution of 6, Adsorption rate reached 96% during the 2.5 h static adsorption time. Using 3.0 mol x L(-1) HCI as the best desorption solvent to desorb the adsorbents, the desorbtion rate reached 98%. Under the best adsorption conditions, the adsorption capacity of Pb(II)-IIPs for Pb(II) was found to be 40. mg x g(-1).

  1. [Toluene, Benzene and Acetone Adsorption by Activated Carbon Coated with PDMS].

    PubMed

    Liu, Han-bing; Jiang, Xin; Wang, Xin; Yang, Bing; Xue, Nan-dong; Zhang, Shi-lei

    2016-04-15

    To improve the adsorption selectivity of volatile organic compounds ( VOCs) , activated carbon ( AC) was modified by polydimethylsiloxane (PDMS) and characterized by BET analysis and Boehm titration. Dynamic adsorption column experiments were conducted and Yoon-Neslon(Y-N) model was used to identify adsorption effect for toluene, beuzene and acetone on AC when relative humidity was 0%, 50% and 90%, respectively. The results showed that the BET area, micropore volume and surface functional groups decreased with the PDMS modification, and surface hydrophobicity of the modified AC was enhanced leading to a lower water adsorption capacity. The results of dynamic adsorption showed that the adsorption kinetics and capacity of Bare-AC decreased with the increase of relative humidity, and the adsorption capacities of PDMS coated AC were 1.86 times (toluene) and 1.92 times (benzene) higher than those of Bare-AC, while a significant improvement of adsorption capacity for acetone was not observed. These findings suggest that polarity of molecule can be an important influencing factor for adsorption on hydrophobic surface developed by PDMS.

  2. Coupled adsorption-photocatalytic degradation of crystal violet under sunlight using chemically synthesized grafted sodium alginate/ZnO/graphene oxide composite.

    PubMed

    Mohamed, S K; Hegazy, Sh H; Abdelwahab, N A; Ramadan, A M

    2018-03-01

    This research aimed to synthesize natural polymer nanocomposite and employ it for coupled adsorption- photocatalytic degradation of crystal violet. Sodium alginate-g-poly (acrylic acid-co-cinnamic acid) and its composites with ZnO nanorods and graphene oxide sheets were synthesized and characterized using FT-IR, XRD, SEM, HR-TEM and DR/UV-vis spectroscopy. The adsorption efficiency of samples for crystal violet has been studied in the dark. The effect of different parameters as pH, initial dye concentration, contact time and temperature on the adsorption efficiency of the synthesized sample has been examined. Kinetics studies showed that the adsorption of all samples was well described by the pseudo-second-order model and the equilibrium adsorption results fitted Freundlich model. The maximum adsorption capacity achieved at pH 5.0 was 13.85 mg g -1 . Thermodynamic studies exhibited that the adsorption is spontaneous, endothermic in nature and leads to higher entropy. Coupled adsorption-photocatalytic degradation studies under sunlight showed an enhancement in the removal efficiency by 10%. In the case of sodium alginate-g-poly (acrylic acid-co-cinnamic acid)/ZnO/graphene oxide composite, the removal efficiency after 5 h under sunlight was 94% versus 84% in the dark. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Adsorption and desorption of oxytetracycline and carbamazepine by multiwalled carbon nanotubes.

    PubMed

    Oleszczuk, Patryk; Pan, Bo; Xing, Baoshan

    2009-12-15

    We investigated the adsorption-desorption by multiwalled carbon nanotubes (MWCNTs) of two pharmaceuticals, oxytetracycline (OTC) and carbamazepine (CBZ). The pharmaceuticals demonstrated relatively fast sorption kinetics on MWCNTs. All adsorption isotherms were nonlinear and fit the Polanyi-Manes model (PMM). The single point adsorption coefficient (K) values for OTC were more than 1 order of magnitude higher than those for CBZ on corresponding MWCNTs. The adsorbed volume capacity (Q(0)) and K values of PMM showed a significant relationship with surface areas and the meso- and micropore volume of MWCNTs for both chemicals. Depending on the MWCNT outer diameter, 13.8-25.2% and 62.7-90.6% of initially adsorbed OTC and CBZ, respectively, were desorbed after 200 h. The rate of desorption of both OTC and CBZ depended upon pH and the quantity of initially adsorbed pharmaceuticals, as well as aggregation in the case of OTC.

  4. Production of granular activated carbon from waste Rosa canina sp. seeds and its adsorption characteristics for dye.

    PubMed

    Gürses, A; Doğar, C; Karaca, S; Açikyildiz, M; Bayrak, R

    2006-04-17

    An activated carbon was developed from Rosa canina sp. seeds, characterized and used for the removal of methylene blue (basic dye) from aqueous solutions. Adsorption studies were carried out at 20 degrees C and various initial dye concentrations (20, 40, 60, 80, and 100 mg/L) for different times (15, 30, 60, and 120 min). The adsorption isotherm was obtained from data. The results indicate that the adsorption isotherm of methylene blue is typically S-shaped. The shape of isotherm is believed to reflect three distinct modes of adsorption. In region 1, the adsorption of methylene blue is carried out mainly by ion exchange. In region 2 by polarizations of pi-electrons established at cyclic parts of the previously adsorbed methylene blue molecules is occurred. However, it is not observed any change at the sign of the surface charge although zeta potential value is decreased with increase of amount adsorbed. In region 3, the slope of the isotherm is reduced, because adsorption now must overcome electrostatic repulsion between oncoming ions and the similarly charged solid. Adsorption in this fashion is usually complete when the surface is covered with a monolayer of methylene blue. To reveal the adsorptive characteristics of the produced active carbon, porosity and BET surface area measurements were made. Structural analysis was performed using SEM-EDS. The produced active carbon has the specific surface area of 799.2 m2 g-1 and the iodine number of 495 mg/g.

  5. Statistical mechanical models for dissociative adsorption of O{sub 2} on metal(100) surfaces with blocking, steering, and funneling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Evans, James W.; Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011; Liu, Da-Jiang

    We develop statistical mechanical models amenable to analytic treatment for the dissociative adsorption of O{sub 2} at hollow sites on fcc(100) metal surfaces. The models incorporate exclusion of nearest-neighbor pairs of adsorbed O. However, corresponding simple site-blocking models, where adsorption requires a large ensemble of available sites, exhibit an anomalously fast initial decrease in sticking. Thus, in addition to blocking, our models also incorporate more facile adsorption via orientational steering and funneling dynamics (features supported by ab initio Molecular Dynamics studies). Behavior for equilibrated adlayers is distinct from those with finite adspecies mobility. We focus on the low-temperature limited-mobility regimemore » where analysis of the associated master equations readily produces exact results for both short- and long-time behavior. Kinetic Monte Carlo simulation is also utilized to provide a more complete picture of behavior. These models capture both the initial decrease and the saturation of the experimentally observed sticking versus coverage, as well as features of non-equilibrium adlayer ordering as assessed by surface-sensitive diffraction.« less

  6. Effect of light on the kinetics and equilibrium of the textile dye (Reactive Red 120) adsorption by Helianthus annuus hairy roots.

    PubMed

    Srikantan, Chitra; Suraishkumar, G K; Srivastava, Smita

    2018-06-01

    The study demonstrates for the first time that light influences the adsorption equilibrium and kinetics of a dye by root culture system. The azo dye (Reactive Red 120) adsorption by the hairy roots of H. annuus followed a pseudo first-order kinetic model and the adsorption equilibrium parameters were best estimated using Langmuir isotherm. The maximum dye adsorption capacity of the roots increased 6-fold, from 0.26 mg g -1 under complete dark conditions to 1.51 mg g -1 under 16/8 h light/dark photoperiod. Similarly, adsorption rate of the dye and removal (%) also increased in the presence of light, irrespective of the initial concentration of the dye (20-110 mg L -1 ). The degradation of the azo dye upon adsorption by the hairy roots of H. annuus was also confirmed. In addition, a strategy for simultaneous dye removal and increased alpha-tocopherol (industrially relevant) production by H. annuus hairy root cultures has been proposed and demonstrated. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Adsorption of Paraquat Dichloride by Graphitic Carbon Nitride Synthesized from Melamine Scraps

    NASA Astrophysics Data System (ADS)

    Watcharenwong, A.; Kaeokan, A.; Rammaroeng, R.; Upama, P.; Kajitvichyanukul, P.

    2017-07-01

    In this research, graphitic carbon nitride (g-C3N4) was synthesized from useless melamine scraps. Mixture of melamine powder and urea was directly burned in the muffle furnace at 550 °C. Later as-synthesized g-C3N4 was modified with hydrochloric acid. The g-C3N4 powder was characterized by several techniques including X-ray diffraction, scanning electron microscope, and specific surface area analyser. Adsorption of the herbicide paraquat from an aqueous solution to suspended particles of g-C3N4 was investigated, taking into consideration several parameters such as initial concentration of paraquat, initial pH, and dosage of g-C3N4. The results showed that with the same amount of g-C3N4, the increase in the paraquat concentration caused the reduction in the removal efficiency and the higher the amount of g-C3N4, the less residual paraquat remained in the bulk solution. G-C3N4 showed better adsorption behaviour in the basic condition. Finally, Langmuir and Freundlich adsorption isotherms were also evaluated. Paraquat adsorption by g-C3N4 was in accordance with Langmuir more than Freundlich adsorption isotherm.

  8. Adsorption and excess fission Xe - Adsorption of Xe on vacuum crushed minerals

    NASA Technical Reports Server (NTRS)

    Bernatowicz, T. J.; Kramer, F. E.; Podosek, F. A.; Honda, M.

    1982-01-01

    It is hypothesized that adsorption is not likely to provide a sufficiently precise mechanism for the concentration of excess fission Xe in the entire lunar regolith, in view of laboratory analogs of the lunar soil and calculations of the residence times of noble gases in the present day regolith. Lunar cold trap and episodic degassing models are difficult to reconcile, however, with the generality of excess fission Xe in all gas-rich highland breccias. It is concluded that the high Xe concentration in such highland breccias is not the result of Xe adsorption prior to the trapping of this component.

  9. Hawaii Energy and Environmental Technologies (HEET) Initiative

    DTIC Science & Technology

    2011-12-01

    polymer electrolyte fuel cells ( PEMFCs ) performance. This work was performed to support the DOE manufacturing initiative for PEMFC production. The work...performed by exposing the MEA cathode to 10 ppm SO2 in N2 at certain potential and typical operating conditions of a PEMFC for certain time, then...adsorbate by analyzing the electrochemical reduction and oxidation potential and charge. As for the in-situ SO2 adsorption experiments, a PEMFC under

  10. Spatial variation of charge and sulfur oxidation state in a surface gradient affects plasma proteins adsorption

    PubMed Central

    Ding, Yong-Xue; Streitmatter, Seth; Wright, Bryon E.; Hlady, Vladimir

    2010-01-01

    A gradient of negative surface charge based on 1-D spatial variation from surface sulfhydryl to mixed sulfhydryl-sulfonate moities was prepared by controlled UV oxidation of 3-mercaptopropylsilane monolayer on fused silica. Adsorption of three human plasma proteins, albumin (HSA), immunoglobulin G (IgG), and fibrinogen (Fgn) onto such surface gradient was studied using spatially-resolved total internal reflection fluorescence (TIRF) and autoradiography. Adsorption was measured from dilute solutions equivalent to 1/100 (TIRF, autoradiography), and 1/500 and 1/1000 (autoradiography) of protein’s physiological concentrations in plasma. All three proteins adsorbed more to the non-oxidized sulfhydryl region than to the oxidized, mixed sulfhydryl-sulfonate region of the gradient. In the case of HSA the adsorption contrast along the gradient was largest when the adsorption took place from more dilute protein solutions. Increasing the concentration to 1/100 of protein plasma concentration eliminated the effect of the gradient on HSA adsorption and to the lesser extent on IgG adsorption. In the case of Fgn the greatest adsorption contrast was observed at the highest concentration used. Based on adsorption kinetics, the estimated binding affinity of HSA for the sulfhydryl region what twice the affinity for the mixed sulfhydryl-sulfonate region of the gradient. For IgG and Fgn the initial adsorption was transport-limited and the initial adsorption rates approached the computed flux of the protein to the surface. PMID:20568822

  11. Comparative study on the copper activation and xanthate adsorption on sphalerite and marmatite surfaces

    NASA Astrophysics Data System (ADS)

    Liu, Jian; Wang, Yu; Luo, Deqiang; Chen, Luzheng; Deng, Jiushuai

    2018-05-01

    The copper activation and potassium butyl xanthate (PBX) adsorption on sphalerite and marmatite surfaces were comparatively investigated using in situ local electrochemical impedance spectroscopy (LEIS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and surface adsorption tests. Comparing the LEIS and surface adsorption results, it was found that the activation time is a key factor influencing the copper activation and PBX adsorption on marmatite surface, but it has a negligible influence on sphalerite. For a short activation time within 10 min, the Fe impurity in marmatite shows an adverse influence on the speed of Cu adsorption and ion exchange as well as on the subsequent PBX adsorption. For a long activation time of 30 min, the LEIS, ToF-SIMS and surface adsorption results suggested that the Fe impurity in marmatite enhances the copper adsorption, whereas such enhanced copper adsorption of marmatite cannot result in corresponding enhancing of PBX adsorption. DFT result showed that the Fe impurity in marmatite has harmful influence on the PBX interaction with the Cu-activated surface by increasing the interaction energy. ToF-SIMS result further indicated that the Cu distribution in the outermost surface of marmatite is less than that of the sphalerite, which also results in the less PBX adsorption for the marmatite.

  12. Amine-functionalized PVA-co-PE nanofibrous membrane as affinity membrane with high adsorption capacity for bilirubin.

    PubMed

    Wang, Wenwen; Zhang, Hao; Zhang, Zhifeng; Luo, Mengying; Wang, Yuedan; Liu, Qiongzhen; Chen, Yuanli; Li, Mufang; Wang, Dong

    2017-02-01

    In this study, poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibrous membrane was activated by sodium hydroxide and cyanuric chloride, and then the activated membranes were functionalized by 1,3-propanediamine, hexamethylenediamine and diethylenetriamine to be affinity membranes for bilirubin removal, respectively. The chemical structures and morphologies of membranes were investigated by SEM, FTIR and XPS. And the adsorption ability of different amine-functionalized nanofibrous membranes for bilirubin was characterized. Furthermore, the effects of temperature, initial concentration of bilirubin, NaCl concentration and BSA concentration on the adsorption capacity for bilirubin of diethylenetriamine-functionalized nanofibrous membrane were studied. Results indicated that the adsorption capacity for bilirubin of diethylenetriamine-functionalized nanofibrous membrane could reach 85mg/g membrane when the initial bilirubin concentration was 200mg/L while the adsorption capacity could be increased to 110mg/g membrane if the initial bilirubin concentration was more than 400mg/L. The dynamic adsorption of diethylenetriamine-functionalized nanofibrous membrane showed that the ligands of amine groups on the membrane surface could be used as far as possible by recirculating the plasma with certain flow rates. Therefore, the diethylenetriamine-functionalized PVA-co-PE nanofibrous membrane possessed high adsorption capacity for bilirubin and it can be candidate as affinity membrane for bilirubin removal. Copyright © 2016. Published by Elsevier B.V.

  13. Kinetic and isotherm studies of bisphenol A adsorption onto orange albedo(Citrus sinensis): Sorption mechanisms based on the main albedo components vitamin C, flavones glycosides and carotenoids.

    PubMed

    Kamgaing, Theophile; Doungmo, Giscard; Melataguia Tchieno, Francis Merlin; Gouoko Kouonang, Jimmy Julio; Mbadcam, Ketcha Joseph

    2017-07-03

    Orange albedo and its adsorption capacity towards bisphenol A (BPA) were studied. Adsorption experiments were conducted in batch mode at 25-55°C. Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and Fourier transform infrared (FTIR) spectroscopy were used to characterise the biosorbent. The effects of various parameters including adsorption time, equilibrium pH, adsorbent dosage and initial adsorbate concentration were investigated. The optimum contact time and pH for the removal of BPA were 60 min and 2, respectively. It was found that the adsorption isotherms best matched the Freundlich model, the adsorption of BPA being multilayer and that of the albedo surface heterogeneous. From the kinetic studies, it was found that the removal of BPA best matched the pseudo-second order kinetic model. An adsorption mechanism based on the albedo surface molecules is proposed and gives a good account of π-π interactions and hydrogen bonding. Orange albedo, with a maximum BPA loading capacity of 82.36 mg g -1 (significantly higher than that of most agricultural residues), is a good candidate for BPA adsorption in aqueous media.

  14. The synthesis of super-small nano hydroxyapatite and its high adsorptions to mixed heavy metallic ions.

    PubMed

    Jing, Nan; Zhou, An-Nan; Xu, Qing-Hong

    2018-03-01

    A "molecular cage" was possibly built in glucose alkaline solution to limit the chemical reaction in a tiny space to control the size and morphology of HA nanoparticles. A possible reaction mechanism of HA nanoparticles confined space synthesis was proposed in this work. The super-small HA nanoparticles were successfully obtained in the first time in mild and green condition which had a 7 nm diameter. The adsorptions to Pb 2+ , Zn 2+ , Ni 2+ , Cd 2+ ions in their mixture solution by the synthesized HA nanoparticles were studied. The adsorbent showed huge adsorption capacities for the targets (Pb 2+  = 3289 mg/g, Zn 2+  = 3150 mg/g, Ni 2+  = 3061 mg/g and Cd 2+  = 2784 mg/g), which indicated an excellent performance of the synthesized nano material in water treatment. Freundlich equation analysis and SEM images of the adsorption products suggested multilayer adsorptions to the targets, and a new recrystalline type adsorption on the surface of the host was found. Some Ca atoms in HA nanoparticles were also found to be substituted by the heavy metallic elements in the initial stage of the adsorptions. The synthesized nano material exhibits better application prospect in wastewater treatment field for its easy synthesis, low-cost and environmental friendly properties. Copyright © 2018. Published by Elsevier B.V.

  15. Adsorptive performance of MOF nanocomposite for methylene blue and malachite green dyes: Kinetics, isotherm and mechanism.

    PubMed

    Alqadami, Ayoub Abdullah; Naushad, Mu; Alothman, Z A; Ahamad, Tansir

    2018-06-06

    In the present study, Fe 3 O 4 @AMCA-MIL-53(Al) nanocomposite was utilized for the adsorptive removal of highly toxic MB and MG dyes from aqueous environment. The batch adsorption tests were performed at different contact time, pH, Fe 3 O 4 @AMCA-MIL-53(Al) dose, initial concentration of dyes and temperature. The maximum adsorption capacity of MB and MG dyes onto of Fe 3 O 4 @AMCA-MIL-53(Al) using Langmuir equation was 1.02 and 0.90 m mol/g, respectively. The isotherm and kinetic studies revealed that adsorption data were well fitted to Langmuir isotherm and pseudo-first-order kinetics models. Various thermodynamic parameters were also calculated and interpreted. The positive and negative values of ΔH° and ΔG° indicated that the adsorption was endothermic and spontaneous, respectively. The adsorptive binding of MB and MG on Fe 3 O 4 @AMCA-MIL53(Al) nanocomposite was directed by carboxylate and amide groups through electrostatic interaction, π-π interaction and hydrogen bonding. The desorption of both dyes from Fe 3 O 4 @AMCA-MIL-53(Al) was also performed using mixed solution of 0.01 M HCl/ethanol. Thus, we conclude that the Fe 3 O 4 @AMCA-MIL-53(Al) was an outstanding material for the removal of dyes from aqueous environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Fabrication of CMC-g-PAM superporous polymer monoliths via eco-friendly Pickering-MIPEs for superior adsorption of methyl violet and methylene blue

    NASA Astrophysics Data System (ADS)

    Wang, Feng; Zhu, Yongfeng; Wang, Wenbo; Zong, Li; Lu, Taotao; Wang, Aiqin

    2017-06-01

    A series of superporous carboxymethylcellulose-graft-poly(acrylamide) (CMC-g-PAM) polymer monoliths presenting interconnected pore structure and excellent adsorption properties were prepared by one-step free-radical grafting polymerization reaction of CMC and acrylamide (AM) in the oil-in-water (O/W) Pickering-medium internal phase emulsions (Pickering-MIPEs) composed of non-toxic edible oil as a dispersion phase and natural Pal nanorods as stabilizers. The effects of Pal dosage, AM dosage, and co-surfactant Tween-20 (T-20) on the pore structures of the monoliths were studied. It was revealed that the well-defined pores were formed when the dosages of Pal and T-20 are 9-14% and 3%, respectively. The porous monolith can rapidly adsorb 1585 mg/g of methyl violet (MV) and 1625 mg/g of methylene blue (MB). After the monolith was regenerated by adsorption-desorption process for 5 times, the adsorption capacities still reached 92.1% (for MV) and 93.5% (for MB) of the initial maximum adsorption capacities. The adsorption process was fitted with Langmuir adsorption isotherm model and pseudo-second-order adsorption kinetic model very well, which indicate that mono-layer chemical adsorption mainly contribute to the high-capacity adsorption for dyes. The superporous polymer monolith prepared from eco-friendly Pickering-MIPEs shows good adsorption capacity and fast adsorption rate, which is potential adsorbent for the decontimination of dye-containing wastewater.

  17. Application of Box-Behnken design for modeling of lead adsorption onto unmodified and NaCl-modified zeolite NaA obtained from biosilica.

    PubMed

    Terzioğlu, Pinar; Yücel, Sevil; Öztürk, Mehmet

    2017-01-01

    The main objective of the present study was to optimize lead adsorption onto zeolite NaA. For this purpose, to synthesize zeolite NaA under hydrothermal conditions, local wheat husk was precleaned with chemical treatment using hydrochloric acid solution. The unmodified (ZU) and NaCl-modified (ZN) zeolites were characterized by Brunauer-Emmett-Teller, scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffraction. The optimization of adsorption process was examined using Box-Behnken Experimental Design in response surface methodology by Design Expert Version 7.0.0 (Stat-Ease, USA). The effects of initial lead (II) concentration, temperature, and time were selected as independent variables. Lack of fit test indicates that the quadratic regression model was significant with the high coefficients of determination values for both adsorbents. Optimum process conditions for lead (II) adsorption onto ZU and ZN were found to be 64.40°C and 64.80°C, respectively, and 90.80 min, and 350 mg L -1 initial lead(II) concentration for both adsorbents. Under these conditions, maximum adsorption capacities of ZU and ZN for lead (II) were 293.38 mg g -1 and 321.85 mg g -1 , respectively.

  18. Adsorption of polycyclic aromatic hydrocarbons by graphene and graphene oxide nanosheets.

    PubMed

    Wang, Jun; Chen, Zaiming; Chen, Baoliang

    2014-05-06

    The adsorption of naphthalene, phenanthrene, and pyrene onto graphene (GNS) and graphene oxide (GO) nanosheets was investigated to probe the potential adsorptive sites and molecular mechanisms. The microstructure and morphology of GNS and GO were characterized by elemental analysis, XPS, FTIR, Raman, SEM, and TEM. Graphene displayed high affinity to the polycyclic aromatic hydrocarbons (PAHs), whereas GO adsorption was significantly reduced after oxygen-containing groups were attached to GNS surfaces. An unexpected peak was found in the curve of adsorption coefficients (Kd) with the PAH equilibrium concentrations. The hydrophobic properties and molecular sizes of the PAHs affected the adsorption of G and GO. The high affinities of the PAHs to GNS are dominated by π-π interactions to the flat surface and the sieving effect of the powerful groove regions formed by wrinkles on GNS surfaces. In contrast, the adsorptive sites of GO changed to the carboxyl groups attaching to the edges of GO because the groove regions disappeared and the polar nanosheet surfaces limited the π-π interactions. The TEM and SEM images initially revealed that after loading with PAH, the conformation and aggregation of GNS and GO nanosheets dramatically changed, which explained the observations that the potential adsorption sites of GNS and GO were unusually altered during the adsorption process.

  19. Mass transport in micellar surfactant solutions: 2. Theoretical modeling of adsorption at a quiescent interface.

    PubMed

    Danov, K D; Kralchevsky, P A; Denkov, N D; Ananthapadmanabhan, K P; Lips, A

    2006-01-31

    Here, we apply the detailed theoretical model of micellar kinetics from part 1 of this study to the case of surfactant adsorption at a quiescent interface, i.e., to the relaxation of surface tension and adsorption after a small initial perturbation. Our goal is to understand why for some surfactant solutions the surface tension relaxes as inverse-square-root of time, 1/t(1/2), but two different expressions for the characteristic relaxation time are applicable to different cases. In addition, our aim is to clarify why for other surfactant solutions the surface tension relaxes exponentially. For this goal, we carried out a computer modeling of the adsorption process, based on the general system of equations derived in part 1. This analysis reveals the existence of four different consecutive relaxation regimes (stages) for a given micellar solution: two exponential regimes and two inverse-square-root regimes, following one after another in alternating order. Experimentally, depending on the specific surfactant and method, one usually registers only one of these regimes. Therefore, to interpret properly the data, one has to identify which of these four kinetic regimes is observed in the given experiment. Our numerical results for the relaxation of the surface tension, micelle concentration and aggregation number are presented in the form of kinetic diagrams, which reveal the stages of the relaxation process. At low micelle concentrations, "rudimentary" kinetic diagrams could be observed, which are characterized by merging of some stages. Thus, the theoretical modeling reveals a general and physically rich picture of the adsorption process. To facilitate the interpretation of experimental data, we have derived convenient theoretical expressions for the time dependence of surface tension and adsorption in each of the four regimes.

  20. Adsorption of dextrin on hydrophobic minerals.

    PubMed

    Beaussart, Audrey; Mierczynska-Vasilev, Agnieszka; Beattie, David A

    2009-09-01

    The adsorption of dextrin on talc, molybdenite, and graphite (three naturally hydrophobic minerals) has been compared. Adsorption isotherms and in situ tapping mode atomic force microscope (TMAFM) imaging have enabled polymer adsorbed amount and morphology of the adsorbed layer (area coverage and polymer domain size) to be determined and also the amount of hydration water in the structure of the adsorbed layer. The effect of the polymer on the mineral contact angles, measured by the captive bubble method on cleaved mineral surfaces, indicates clear correlations between the hydrophobicity reduction of the minerals, the adsorbed amount, and the surface coverage of the adsorbed polymer. Predictions of the flotation recovery of the treated mineral phases have been confirmed by performing batch flotation experiments. The influence of the polymer surface coverage on flotation recovery has highlighted the importance of this key parameter in the predictions of depressant efficiency. The roles of the initial hydrophobicity and the surface structure of the mineral basal plane in determining adsorption parameters and flotation response of the polymer-treated minerals are also discussed.

  1. Selective Adsorption and Separation of Organic Dyes with Spherical Polyelectrolyte Brushes and Compressed Carbon Dioxide.

    PubMed

    Zhang, Rui; Yu, Zhenchuan; Wang, Lei; Shen, Qizhe; Hou, Xiaoyan; Guo, Xuhong; Wang, Junwei; Zhu, Xuedong; Yao, Yuan

    2017-10-04

    Dye-containing wastewater has caused serious environmental pollution. Herein, rationally designed spherical polyelectrolyte brushes (SPBs) with cationic charges, polystyrene-poly(2-aminoethylmethacrylate hydrochloride) (PS-PAEMH) as the absorbent, and compressed carbon dioxide as the antisolvent are proposed for the separation of the anionic dye eosin Y (EY) from a solution of mixed dyes. The adsorption behavior of EY onto PS-PAEMH was highly dependent on CO 2 pressure, contact time, and initial concentration. The maximum adsorption capacity of PS-PAEMH was 335.20 mg g -1 . FTIR and UV/Vis measurements proved that the electrostatic interactions between EY and PS-PAEMH played an important role in the absorbance process. The adsorption process fitted the pseudo-second-order kinetic model and Freundlich isotherm model very well. The combined dye and polymer brush could be easily separated through ion exchange by adding an aqueous solution of NaCl. Recovered PS-PAEMH retained a high adsorption capacity even after ten cycles of regeneration. This method provides a simple and effective way to separate ionic materials for environmental engineering. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Factors affecting adsorption characteristics of Zn2+ on two natural zeolites.

    PubMed

    Oren, Ali Hakan; Kaya, Abidin

    2006-04-17

    Mining-related and industrial wastes are primary sources of heavy metal contamination in soils and groundwater. The limitation of such waste in drinking water needs to meet government requirements in order to safeguard human health and environment. Zinc, one of the most preponderant pollutants, is difficult to remove from wastewater rather than other heavy metals (i.e. lead, copper and cadmium). This paper investigates Zn2+ adsorption characteristics of two natural zeolites found in the regions of Gordes and Bigadic, in western Turkey. The results show that the Zn2+ adsorption behavior of both zeolites is highly dependent on the pH. Adsorption dependence on lower pH values (pH<4) is explained by the dissolution of crystal structure and the competition of the zinc ions with the H+. Between pH 4 and 6, the basic mechanism is the ion exchange process. The results also showed that decrease in grain size does not increase the adsorption capacity of zeolite from Gordes, yet it increases that of zeolite from Bigadic about 23%. The results also reveal that an increase in the initial concentration of Zn2+ in the system causes an increase in the adsorption capacity to a degree, then it becomes more constant at higher concentrations. With this, the removal efficiency of Gordes zeolite is two times higher than that of Bigadic zeolite. Results show that an increase in slurry concentration results in a lower uptake of Zn2+. In the final part of the paper, we compared the experimental data with the Langmuir and Freundlich isotherms. The results show that there is a good fit between the experimental data and empirical isotherms.

  3. Fabrication of cellulose nanocrystal from Carex meyeriana Kunth and its application in the adsorption of methylene blue.

    PubMed

    Yang, Xue; Liu, Hui; Han, Fuyi; Jiang, Shuai; Liu, Lifang; Xia, Zhaopeng

    2017-11-01

    Cellulose nanocrystal (CNC) was extracted from Carex meyeriana Kunth (CMK) by a combination of TEMPO oxidation and mechanical homogenization method, and used to remove methylene blue (MB) from aqueous solution. After alkali-oxygen treatment, the aqueous biphasic system (polyethylene glycol/inorganic salt) was applied to further remove lignin from CMK. The characteriazation of CNC, and the effects of H 2 O 2 dosage, CNC dosage, adsorption time, and initial MB concentration on the MB removal capacity of CNC were investigated. The results showed that the removal percentage of MB by CNC was raised with the increase of H 2 O 2 and CNC dosage. The adsorption kinetics of prepared CNC followed the pseudo-second-order model, and the adsorption isotherms fitted well to the Langmuir model with a calculated maximum adsoption capacity of 217.4mg/g, which was higher than those of CNC extracted by acid hydrolysis method, indicating CNC extracted from CMK had promising potentials in the field of MB adsorption. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Comparison of adsorption equilibrium models and error functions for the study of sulfate removal by calcium hydroxyapatite microfibrillated cellulose composite.

    PubMed

    Hokkanen, Sanna; Bhatnagar, Amit; Koistinen, Ari; Kangas, Teija; Lassi, Ulla; Sillanpää, Mika

    2018-04-01

    In the present study, the adsorption of sulfates of sodium sulfate (Na 2 SO 4 ) and sodium lauryl sulfate (SLS) by calcium hydroxyapatite-modified microfibrillated cellulose was studied in the aqueous solution. The adsorbent was characterized using elemental analysis, Fourier transform infrared, scanning electron microscope and elemental analysis in order to gain the information on its structure and physico-chemical properties. The adsorption studies were conducted in batch mode. The effects of solution pH, contact time, the initial concentration of sulfate and the effect of competing anions were studied on the performance of synthesized adsorbent for sulfate removal. Adsorption kinetics indicated very fast adsorption rate for sulfate of both sources (Na 2 SO 4 and SLS) and the adsorption process was well described by the pseudo-second-order kinetic model. Experimental maximum adsorption capacities were found to be 34.53 mg g -1 for sulfates of SLS and 7.35 mg g -1 for sulfates of Na 2 SO 4. The equilibrium data were described by the Langmuir, Sips, Freundlich, Toth and Redlich-Peterson isotherm models using five different error functions.

  5. Separation of lignocelluloses from spent liquor of NSSC pulping process via adsorption.

    PubMed

    Dashtban, Mehdi; Gilbert, Allan; Fatehi, Pedram

    2014-04-01

    Hemicelluloses and lignin present in the spent liquor (SL) of neutral sulfite semichemical (NSSC) pulping process can potentially be converted into value-added products such as furfural, hydroxymethylfurfural, levulinic acid, phenols and adhesives. However, the direct conversion of hemicelluloses and lignin of SL into value-added products is uneconomical due to the dilute nature of the SL. To have a feasible downstream process for utilizing lignocelluloses of SL, the lignocelluloses should initially be separated from the SL. In this study, an adsorption process (via applying activated carbon) was considered for isolating the dissolved lignin and hemicelluloses from the SL of an NSSC pulping process. Under the optimal conditions of pH, SL/AC weight ratio, time and temperature of 5.7, 30, 360 min and 30 °C, the maximum lignin and hemicellulose adsorptions were 0.33 and 0.25 g/g on AC. The chemical oxygen demand (COD) and turbidity of the SL were decreased by 11% and 39%, respectively, as a result of lignocellulose adsorption on AC. Also, the incineration behavior of the SL-treated AC was studied with a thermo-gravimetric analysis (TGA). Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Adsorption of charged albumin subdomains on a graphite surface.

    PubMed

    Raffaini, Giuseppina; Ganazzoli, Fabio

    2006-03-01

    We report some new molecular dynamics simulation results about the adsorption on a hydrophobic graphite surface of two albumin subdomains, each formed by three different alpha-helices, considering the correctly charged side groups at pH = 7 instead of the neutral ones as done in our previous exploratory paper (Raffaini and Ganazzoli, Langmuir 2003;19:3403-3412). We find that the presence of charges affects somewhat the initial adsorption stage on the electrostatically neutral surface, but not the final one. Thus, we recover the result that a monolayer of aminoacids is eventually formed, with a rough parallelism of distant strands to optimize both the intramolecular and the surface interactions. This feature is consistent with the adsorption on the hydrophobic surface being driven by dispersion forces only, and with the "soft" nature of albumin. Additional optimizations of the final monolayer carried out at pH = 3 and 11 do not modify appreciably this picture, suggesting that adsorption on graphite is basically independent of pH. The enhanced hydration of the final adsorption state due to the (delocalized) charges of the side groups is also discussed in comparison with similar results of the neutralized subdomains. (c) 2005 Wiley Periodicals, Inc.

  7. Highly efficient fluoride adsorption from aqueous solution by nepheline prepared from kaolinite through alkali-hydrothermal process.

    PubMed

    Wang, Hao; Feng, Qiming; Liu, Kun; Li, Zishun; Tang, Xuekun; Li, Guangze

    2017-07-01

    A direct alkali-hydrothermal induced transformation process was adopted to prepare nepheline from raw kaolinite (shortened form RK in this paper) and NaOH solution in this paper. Structure and morphology characterizations of the synthetic product showed that the nepheline possessed high degree of crystallinity and uniform surface morphology. Specific surface area of nepheline is 18 m 2 /g, with a point of zero charge at around pH 5.0-5.5. The fluoride (F - ions) adsorption by the synthetic nepheline (shortened form SN in this paper) from aqueous solution was also investigated under different experimental conditions. The adsorption process well matched the Langmuir isotherm model with an amazing maximum adsorption capacity of 183 mg/g at 323 K. The thermodynamic parameters (ΔG 0 , ΔH 0 , and ΔS 0 ) for adsorption on SN were also determined from the temperature dependence. The adsorption capacities of fluoride on SN increased with increasing of temperature and initial concentration. Initial pH value also had influence on adsorption process. Adsorption of fluoride was rapidly increased in 5-60 min and thereafter increased slowly to reach the equilibrium in about 90-180 min under all conditions. The adsorption followed a pseudo-second order rate law. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Phosphorus removal by electric arc furnace steel slag adsorption

    NASA Astrophysics Data System (ADS)

    Lim, J. W.; Lee, K. F.; Chong, Thomas S. Y.; Abdullah, L. C.; Razak, M. A.; Tezara, C.

    2017-10-01

    As to overcome the eutrophication in lakes and reservoirs which is resulted from excessive input of phosphorus due to rapid urbanization or uncontrolled agricultural activities, Electric Arc Furnace steel slag (EAFS), a steelmaking by-product, in which the disposal of this industrial waste considered economically unfavourable yet it’s physical and chemical properties exhibits high potential to be great P adsorbent. The objective of this study was to identify most suitable mathematical model in description of adsorption by using traditional batch experiment and to investigate the effect on Phosphorus removal efficiency and Phosphorus removal capacity by EAFS adsorption through variation of parameters such as pH, size of slag and initial concentration of Phosphorus. Result demonstrated that, Langmuir is suitable in describing Phosphorus removal mechanisms with the Maximum Adsorption Capacity, Q m of 0.166 mg/g and Langmuir Constant, KL of 0.03519 L/mg. As for effect studies, smaller size of adsorbent shows higher percentage (up to 37.8%) of Phosphorus removal compared to the larger size. Besides that, the experiment indicated a more acidic environment is favourable for Phosphorus removal and the amount of Phosphorus adsorbed at pH 3.0 was the highest. In addition, the adsorption capacity increases steadily as the initial Phosphorus concentration increases but it remained steady at 100mg P/L. Eventually, this study serves as better understanding on preliminary studies of P removal mechanisms by EAFS.

  9. Adsorption of dissymmetric cationic gemini surfactants at silica/water interface

    NASA Astrophysics Data System (ADS)

    Sun, Yuhai; Feng, Yujun; Dong, Hongwei; Chen, Zhi

    2007-05-01

    Adsorption of a series of cationic gemini surfactants 12-2- m ( m = 8, 12, 16) on the surface of silica was investigated. The critical micelle concentrations, cmcs, of cationic gemini surfactants in the initial solutions and in the supernatants were measured by conductometry and tensiometer. The changes in cmc values indicate that the ion exchanges take place between polar groups of gemini surfactants adsorbed and ions bound on the surface of silica. The adsorption isotherms of cationic gemini surfactants were obtained by a solution depletion method. Based on the driving force, the adsorption includes two steps, one of which is ion exchange, and the other is hydrophobic interaction. In each step, the tendency of surfactant molecules in the solution to form aggregates or to be adsorbed on the silica varies with their structures. The maximum adsorption amount of gemini surfactants on the silica, τmax, decreases as increasing in the length of one alkyl chain, m, from 8, 12 to 16. So the results show that the adsorption behaviors of gemini surfactants are closely related to the dissymmetry of gemini molecules.

  10. Adsorptive removal of 2-chlorophenol by low-cost coir pith carbon.

    PubMed

    Namasivayam, C; Kavitha, D

    2003-03-17

    Adsorption of 2-chlorophenol (2-CP) by coir pith carbon was carried out by varying the parameters such as agitation time, 2-CP concentration, adsorbent dose, pH and temperature. Adsorption equilibrium reached at 40, 60, 80 and 100 min for 2-CP concentration of 10, 20, 30 and 40 mg/l, respectively. Adsorption followed second-order kinetics. The adsorption equilibrium data obeyed Freundlich isotherm. Acidic pH was favorable for the adsorption of 2-CP. Desorption studies showed that chemisorption plays a major role in the adsorption process. Copyright 2003 Elsevier Science B.V.

  11. Thermodynamics of organic molecule adsorption on sorbents modified with 5-hydroxy-6-methyluracil by inverse gas chromatography.

    PubMed

    Gus'kov, Vladimir Yu; Gainullina, Yulia Yu; Ivanov, Sergey P; Kudasheva, Florida Kh

    2014-08-22

    The thermodynamic features of organic molecule adsorption from the gaseous phase of sorbents modified with 5-hydroxy-6-methyluracil (HMU) were studied. Molar internal energy and entropy of adsorption variation analyses showed that with every type surface, except for silica gel, layers of supramolecular structure have cavities equal in size with the ones revealed in HMU crystals by X-ray diffraction. Adsorption thermodynamics on HMU-modified sorbents depended on the amount of impregnated HMU and on the polarity, but not the porosity, of the initial sorbent. Polarity of the modified surface increased as a function of HMU quantity and initial sorbent mean pore size, but become appreciably lower if the initial surface is capable of hydrogen bonding. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Summary of Adsorption Capacity and Adsorption Kinetics of Uranium and Other Elements on Amidoxime-based Adsorbents from Time Series Marine Testing at the Pacific Northwest National Laboratory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gill, Gary A.; Kuo, Li-Jung; Strivens, Jonathan E.

    The Pacific Northwest National Laboratory (PNNL) has been conducting marine testing of uranium adsorbent materials for the Fuel Resources Program, Department of Energy, Office of Nuclear Energy (DOE-NE) beginning in FY 2012. The marine testing program is being conducted at PNNL’s Marine Sciences Laboratory (MSL), located at Sequim Bay, along the coast of Washington. One of the main efforts of the marine testing program is the determination of adsorption capacity and adsorption kinetics for uranium and selected other elements (e.g. vanadium, iron, copper, nickel, and zinc) for adsorbent materials provided primarily by Oak Ridge National Laboratory (ORNL), but also includesmore » other Fuel Resources Program participants. This report summarizes the major marine testing results that have been obtained to date using time series sampling for 42 to 56 days using either flow-through column or recirculating flume exposures. The major results are highlighted in this report, and the full data sets are appended as a series of Excel spreadsheet files. Over the four year period (2012-2016) that marine testing of amidoxime-based polymeric adsorbents was conducted at PNNL’s Marine Science Laboratory, there has been a steady progression of improvement in the 56-day adsorbent capacity from 3.30 g U/kg adsorbent for the ORNL 38H adsorbent to the current best performing adsorbent prepared by a collaboration between the University of Tennessee and ORNL to produce the adsorbent SB12-8, which has an adsorption capacity of 6.56 g U/kg adsorbent. This nearly doubling of the adsorption capacity in four years is a significant advancement in amidoxime-based adsorbent technology and a significant achievement for the Uranium from Seawater program. The achievements are evident when compared to the several decades of work conducted by the Japanese scientists beginning in the 1980’s (Kim et al., 2013). The best adsorbent capacity reported by the Japanese scientists was 3.2 g U

  13. [Adsorption of perfluorooctanesulfonate (PFOS) onto modified activated carbons].

    PubMed

    Tong, Xi-Zhen; Shi, Bao-You; Xie, Yue; Wang, Dong-Sheng

    2012-09-01

    Modified coal and coconut shell based powdered activated carbons (PACs) were prepared by FeCl3 and medium power microwave treatment, respectively. Batch experiments were carried out to evaluate the characteristics of adsorption equilibrium and kinetics of perfluorooctanesulfonate (PFOS) onto original and modified PACs. Based on pore structure and surface functional groups characterization, the adsorption behaviors of modified and original PACs were compared. The competitive adsorption of humic acid (HA) and PFOS on original and modified coconut shell PACs were also investigated. Results showed that both Fe3+ and medium power microwave treatments changed the pore structure and surface functional groups of coal and coconut shell PACs, but the changing effects were different. The adsorption of PFOS on two modified coconut shell-based PACs was significantly improved. While the adsorption of modified coal-based activated carbons declined. The adsorption kinetics of PFOS onto original and modified coconut shell-based activated carbons were the same, and the time of reaching adsorption equilibrium was about 6 hours. In the presence of HA, the adsorption of PFOS by modified PAC was reduced but still higher than that of the original.

  14. Impact of concentration and species of sulfamethoxazole and ofloxacin on their adsorption kinetics on sediments.

    PubMed

    Wang, Peng; Zhang, Di; Zhang, Huang; Li, Hao; Ghosh, Saikat; Pan, Bo

    2017-05-01

    Antibiotics are used widely in human and veterinary medicine and are ubiquitous in environmental matrices worldwide. The influence of the concentration of antibiotics on adsorption kinetics is still unclear. This study used sulfamethoxazole (SMX) and ofloxacin (OFL) as adsorbates to investigate the adsorption kinetics on sediment affected by varying concentrations of antibiotics adsorbable species. At the experimental pH values, the major adsorbed species of SMX and OFL on sediment were SMX 0 and OFL + by hydrophobic interaction and electrostatic attraction, respectively. The apparent adsorption rate of SMX was not affected by the initial concentration and the pH values because the hydrophobic interactions were concentration-independent and charge-independent. However, the apparent adsorption rate of OFL significantly slowed down as the initial concentration increased. The adsorbed OFL + effectively neutralized the negative charges of the sediment, leading to a reduced adsorption rate of subsequent OFL + . The neutralization effect was greatly enhanced due to the increased OFL + with the increasing OFL concentration. Additionally, the apparent adsorption rate of OFL significantly increased at higher pH due to the reduced neutralization effect that resulted from the decreased OFL + and increased negative charges of the sediment surface. This study implied that the adsorption kinetics of antibiotics was greatly dominated by the concentration of adsorbable species rather than apparent overall concentration. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. [Effects of soil trituration size on adsorption of oxytetracycline on soils].

    PubMed

    Qi, Rui-Huan; Li, Zhao-Jun; Long, Jian; Fan, Fei-Fei; Liang, Yong-Chao

    2011-02-01

    In order to understand the effects of soil trituration size on adsorption of oxytetracycline (OTC) on soils, two contrasting soils including moisture soil and purplish soil were selected to investigate adsorption of OTC on these soils, at the scales of no more than 0.20 mm, 0.84 mm, 0.25 mm and 0.15 mm, using the method of batch equilibrium experiments respectively. The results presented as the following: (1) Adsorption amount of OTC on moisture soil and purplish soil increased with the sampling time, and reached to equilibration at 24 h. First-order kinetic model, second-order kinetic model, parabolic-diffusion kinetic model, Elovich kinetic model, and two-constant kinetic model could be used to fit the changes in adsorption on soils with sampling time. Adsorption of OTC on two soils consisted of two processes such as quick adsorption and slow adsorption. Quick adsorption process happened during the period of 0-0.5 h. The adsorption rates of OTC on soils were higher at the small trituration size than those at the large trituration size, and at the same trituration size, the k(f) of purplish soil was about two times higher than those of moisture soil. (2) Adsorption isotherms of OTC on two soils with different trituration sizes were deviated from the linear model. The data were fitted well to Freundlich and Langmuir models, with the correlation coefficients between 0.956 and 0.999. The values of k(f) and q(m) for purplish soil were higher than those for moisture soil. At the same soil, adsorption amount of OTC increased with the decreases of soil trituration size. The results suggested that it is important to select the appropriate trituration size, based on the physical and chemical properties such as soil particle composition and so on, when the fate of antibiotics on soils was investigated.

  16. Ultrasonic-assisted synthesis of superabsorbent hydrogels based on sodium lignosulfonate and their adsorption properties for Ni2.

    PubMed

    Wang, Xiaohong; Wang, Yingying; He, Shufu; Hou, Haiqian; Hao, Chen

    2018-01-01

    Nowadays, the attention of both academic and industrial research is paid to the novel materials based on renewable organic resources. Sodium lignosulphonate (SLS) is selected in this study to synthesize novel superabsorbent hydrogels by ultrasonic polymerization. The structure, morphology and stability of SLS-based hydrogel were confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Under the optimal condition, SLS-based hydrogel possesses the water absorbency of 1328g·g -1 in distilled water and 110g·g -1 in 0.9wt% NaCl solution. In addition, the prepared SLS-hydrogel as an adsorbent was applied to remove Ni 2+ from an aqueous solution in virtue of its low cost and favorable adsorption capacity. The various experimental conditions that influence the adsorption capacity were investigated such as temperature (20-60°C), pH (2.0-7.0), contact time (0-360min) and initial concentration of the Ni 2+ solution (100-600mg·L -1 ). Then the adsorption capability could reach 293mg·g -1 under optimal conditions. The results revealed that the adsorption behavior is spontaneous and endothermic. Furthermore, it was observed that the adsorption mechanism and adsorption equilibrium data obeyed pseudo-second-order kinetic and Freundlich models. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Enhanced adsorptive removal of Safranine T from aqueous solutions by waste sea buckthorn branch powder modified with dopamine: Kinetics, equilibrium, and thermodynamics

    NASA Astrophysics Data System (ADS)

    Xu, Xiaohui; Bai, Bo; Wang, Honglun; Suo, Yourui

    2015-12-01

    Polydopamine coated sea buckthorn branch powder (PDA@SBP) was facilely synthesized via a one-pot bio-inspired dip-coating approach. The as-synthesized PDA@SBP was characterized using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The adsorption progresses of Safranine T on the surface of PDA@SBP adsorbent were systematically investigated. More specifically, the effects of solution pH, contact time, initial concentration and temperature were evaluated, respectively. The experimental results showed the adsorption capacity of PDA@SBP at 293.15 K could reach up to 54.0 mg/g; the adsorption increased by 201.7% compared to that of native SBP (17.9 mg/g). Besides, kinetics studies showed that pseudo-second-order kinetic model adequately described the adsorption behavior. The adsorption experimental data could be fitted well a Freundlich isotherm model. Thermodynamic analyses showed that the ST adsorption was a physisorption endothermic process. Regeneration of the spent PDA@SBP adsorbent was conducted with 0.1 M HCl without significant reduction in adsorption capacity. On the basis of these investigations, it is believed that the PDA@SBP adsorbent could have potential applications in sewage disposal areas because of their considerable adsorption capacities, brilliant regeneration capability, and cost-effective and eco-friendly preparation and use.

  18. Adsorption of phospholipids at oil/water interfaces during emulsification is controlled by stress relaxation and diffusion.

    PubMed

    Hildebrandt, Ellen; Nirschl, Hermann; Kok, Robbert Jan; Leneweit, Gero

    2018-05-16

    Adsorption of phosphatidylcholines at oil/water interfaces strongly deviates from spread monolayers at air/water surfaces. Understanding its nature and consequences could vastly improve applications in medical nanoemulsions and biotechnologies. Adsorption kinetics at interfaces of water with different oil phases were measured by profile analysis tensiometry. Adsorption kinetics for 2 different phospholipids, DPPC and POPC, as well as 2 organic phases, squalene and squalane, show that formation of interfacial monolayers is initially dominated by stress-relaxation in the first minutes. Diffusion only gradually contributes to a decrease in interfacial tension at later stages of time and higher film pressures. The results can be applied for the optimization of emulsification protocols using mechanical treatments. Emulsions using phospholipids with unsaturated fatty acids are dominated much more strongly by stress-relaxation and cover interfaces very fast compared to those with saturated fatty acids. In contrast, phospholipid layers consisting of saturated fatty acids converge faster towards the equilibrium than those with unsaturated fatty acids.

  19. Study on the enhanced adsorption properties of lysozyme on polyacrylic acid modified TiO2 nano-adsorbents

    NASA Astrophysics Data System (ADS)

    Liu, Yufeng; Jin, Zu; Meng, Hao; Zhang, Xia

    2018-01-01

    The adsorption and immobilization of enzymes onto solid carriers has been focused on due to their many advantages, such as improved stability against a thermal or organic solvent and a good cycle usability. TiO2 nanoparticles is one of excellent nano-adsorbents owing to its excellent biocompatibility, non-inflammatory, and abundant surface hydroxyl groups, which are convenient to be combined with various functional groups. In this paper polyacrylic acid (PAA) modified TiO2 nanoparticles were synthesized through an in situ light-induced polymerization of acrylic acid on the surface of TiO2 nanoparticles. The structure and surface physicochemical properties of the PAA/TiO2 nanoparticles were characterized by TEM, XRD, FT-IR, Zeta potential measurements and TG-DSC. The experimental results showed that the isoelectric point of PAA/TiO2 significantly reduced to 1.82 compared with that of pure TiO2 nanoparticles (6.08). In the adsorption tests of lysozyme (Lyz), the PAA/TiO2 nanoparticles displayed enhanced adsorption activity compared with pristine TiO2. The maximum adsorption capacity of PAA/TiO2 for Lyz was 225.9 mg g-1 under the optimum conditions where the initial concentration of Lyz was 300 mg ml-1, the addition amount of PAA/TiO2 was 6.4 mg, the adsorption time was 30 min and the pH value was 7.0. The sodium dodecyl sulfate (SDS, 0.5%) presented the best efficiency (76.86%) in the removal of adsorbed Lyz, and the PAA/TiO2 nanoparticles showed excellent adsorption stability based on five cyclic adsorption-desorption tests. The fitting calculation results of the adsorption isotherm and the thermodynamics indicated the adsorption was an exothermic, entropy increasing, spontaneous and monomolecular layer adsorption process.

  20. Cr(VI) adsorption from electroplating plating wastewater by chemically modified coir pith.

    PubMed

    Suksabye, Parinda; Thiravetyan, Paitip

    2012-07-15

    Coir pith samples were chemically modified by grafting with acrylic acid for the removal of Cr(VI) from electroplating wastewater. The presence of acrylic acid on the coir pith surface was verified by a scanning electron microscope with an electron dispersive x-ray spectrometer (SEM/EDX), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG). The carbonyl groups (C==O) from the carboxylic acids (COOH) increased on the coir pith surface after grafting with acrylic acid. In addition, the thermal stability of the acrylic acid-grafted coir pith also improved. The optimum conditions for grafting the acrylic acid on the coir pith consisted of 2 M acrylic acid and 0.00125 M ceric ammonium nitrate (CAN, as an initiator). The maximum Cr(VI) removal (99.99 ± 0.07%) was obtained with the following conditions: a 1.3% (w/v) dosage of acrylic acid-grafted coir pith, a system pH of 2, a contact time of 22 h, a temperature of 30 °C, a particle size of <150 μm and an initial Cr(VI) of 1,171 mg l(-1). At system pH of 2, Cr(VI) in the HCrO(4)(-) form can be adsorbed with acrylic acid-grafted coir pith via an electrostatic attraction. The adsorption isotherm of 2 M acrylic acid-grafted coir pith exhibited a good fit with the Langmuir isotherm. The maximum Cr(VI) adsorption capacity of the 2 M acrylic acid-grafted coir pith was 196.00 mg Cr(VI) g(-1) adsorbent, whereas for coir pith without grafting, the maximum Cr(VI) removal was 165.00 mg Cr(VI) g(-1) adsorbent. The adsorption capacity of the acrylic acid-grafted coir pith for Cr(VI) was higher compared to the original coir pith. This result was due to the enhancement of the carbonyl groups on the coir pith surface that may have involved the mechanism of chromium adsorption. The X-ray absorption near edged structure (XANES) and desorption studies suggested that most of the Cr(III) that presented on the acrylic acid-grafted coir pith was due to the Cr(VI) being reduced to Cr(III) on the adsorbent surface. FTIR

  1. Fabrication of CMC-g-PAM Superporous Polymer Monoliths via Eco-Friendly Pickering-MIPEs for Superior Adsorption of Methyl Violet and Methylene Blue

    PubMed Central

    Wang, Feng; Zhu, Yongfeng; Wang, Wenbo; Zong, Li; Lu, Taotao; Wang, Aiqin

    2017-01-01

    A series of superporous carboxymethylcellulose-graft-poly(acrylamide)/palygorskite (CMC-g-PAM/Pal) polymer monoliths presenting interconnected pore structure and excellent adsorption properties were prepared by one-step free-radical grafting polymerization reaction of CMC and acrylamide (AM) in the oil-in-water (O/W) Pickering-medium internal phase emulsions (Pickering-MIPEs) composed of non-toxic edible oil as a dispersion phase and natural Pal nanorods as stabilizers. The effects of Pal dosage, AM dosage, and co-surfactant Tween-20 (T-20) on the pore structures of the monoliths were studied. It was revealed that the well-defined pores were formed when the dosages of Pal and T-20 are 9–14 and 3%, respectively. The porous monolith can rapidly adsorb 1,585 mg/g of methyl violet (MV) and 1,625 mg/g of methylene blue (MB). After the monolith was regenerated by adsorption-desorption process for five times, the adsorption capacities still reached 92.1% (for MV) and 93.5% (for MB) of the initial maximum adsorption capacities. The adsorption process was fitted with Langmuir adsorption isotherm model and pseudo-second-order adsorption kinetic model very well, which indicate that mono-layer chemical adsorption mainly contribute to the high-capacity adsorption for dyes. The superporous polymer monolith prepared from eco-friendly Pickering-MIPEs shows good adsorption capacity and fast adsorption rate, which is potential adsorbent for the decontamination of dye-containing wastewater. PMID:28642862

  2. Fabrication of CMC-g-PAM Superporous Polymer Monoliths via Eco-Friendly Pickering-MIPEs for Superior Adsorption of Methyl Violet and Methylene Blue.

    PubMed

    Wang, Feng; Zhu, Yongfeng; Wang, Wenbo; Zong, Li; Lu, Taotao; Wang, Aiqin

    2017-01-01

    A series of superporous carboxymethylcellulose- graft -poly(acrylamide)/palygorskite (CMC- g -PAM/Pal) polymer monoliths presenting interconnected pore structure and excellent adsorption properties were prepared by one-step free-radical grafting polymerization reaction of CMC and acrylamide (AM) in the oil-in-water (O/W) Pickering-medium internal phase emulsions (Pickering-MIPEs) composed of non-toxic edible oil as a dispersion phase and natural Pal nanorods as stabilizers. The effects of Pal dosage, AM dosage, and co-surfactant Tween-20 (T-20) on the pore structures of the monoliths were studied. It was revealed that the well-defined pores were formed when the dosages of Pal and T-20 are 9-14 and 3%, respectively. The porous monolith can rapidly adsorb 1,585 mg/g of methyl violet (MV) and 1,625 mg/g of methylene blue (MB). After the monolith was regenerated by adsorption-desorption process for five times, the adsorption capacities still reached 92.1% (for MV) and 93.5% (for MB) of the initial maximum adsorption capacities. The adsorption process was fitted with Langmuir adsorption isotherm model and pseudo-second-order adsorption kinetic model very well, which indicate that mono-layer chemical adsorption mainly contribute to the high-capacity adsorption for dyes. The superporous polymer monolith prepared from eco-friendly Pickering-MIPEs shows good adsorption capacity and fast adsorption rate, which is potential adsorbent for the decontamination of dye-containing wastewater.

  3. Studies on adsorption, reaction mechanisms and kinetics for photocatalytic degradation of CHD, a pharmaceutical waste.

    PubMed

    Sarkar, Santanu; Bhattacharjee, Chiranjib; Curcio, Stefano

    2015-11-01

    The photocatalytic degradation of chlorhexidine digluconate (CHD), a disinfectant and topical antiseptic and adsorption of CHD catalyst surface in dark condition has been studied. Moreover, the value of kinetic parameters has been measured and the effect of adsorption on photocatalysis has been investigated here. Substantial removal was observed during the photocatalysis process, whereas 40% removal was possible through the adsorption route on TiO2 surface. The parametric variation has shown that alkaline pH, ambient temperature, low initial substrate concentration, high TiO2 loading were favourable, though at a certain concentration of TiO2 loading, photocatalytic degradation efficiency was found to be maximum. The adsorption study has shown good confirmation with Langmuir isotherm and during the reaction at initial stage, it followed pseudo-first-order reaction, after that Langmuir Hinshelwood model was found to be appropriate in describing the system. The present study also confirmed that there is a significant effect of adsorption on photocatalytic degradation. The possible mechanism for adsorption and photocatalysis has been shown here and process controlling step has been identified. The influences of pH and temperature have been explained with the help of surface charge distribution of reacting particles and thermodynamic point of view respectively. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Chlorine adsorption on the InAs (001) surface

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bakulin, A. V.; Eremeev, S. V.; Tereshchenko, O. E.

    2011-01-15

    Chlorine adsorption on the In-stabilized InAs(001) surface with {zeta}-(4 Multiplication-Sign 2) and {beta}3 Prime -(4 Multiplication-Sign 2) reconstructions and on the Ga-stabilized GaAs (001)-{zeta}-(4 Multiplication-Sign 2) surface has been studied within the electron density functional theory. The equilibrium structural parameters of these reconstructions, surface atom positions, bond lengths in dimers, and their changes upon chlorine adsorption are determined. The electronic characteristics of the clean surface and the surface with adsorbed chlorine are calculated. It is shown that the most energetically favorable positions for chlorine adsorption are top positions over dimerized indium or gallium atoms. The mechanism of chlorine binding withmore » In(Ga)-stabilized surface is explained. The interaction of chlorine atoms with dimerized surface atoms weakens surface atom bonds and controls the initial stage of surface etching.« less

  5. Preliminary investigation of phosphorus adsorption onto two types of iron oxide-organic matter complexes.

    PubMed

    Yan, Jinlong; Jiang, Tao; Yao, Ying; Lu, Song; Wang, Qilei; Wei, Shiqiang

    2016-04-01

    Iron oxide (FeO) coated by natural organic matter (NOM) is ubiquitous. The associations of minerals with organic matter (OM) significantly changes their surface properties and reactivity, and thus affect the environmental fate of pollutants, including nutrients (e.g., phosphorus (P)). In this study, ferrihydrite/goethite-humic acid (FH/GE-HA) complexes were prepared and their adsorption characteristics on P at various pH and ionic strength were investigated. The results indicated that the FeO-OM complexes showed a decreased P adsorption capacity in comparison with bare FeO. The maximum adsorption capacity (Qmax) decreased in the order of FH (22.17 mg/g)>FH-HA (5.43 mg/g)>GE (4.67 mg/g)>GE-HA (3.27 mg/g). After coating with HA, the amorphous FH-HA complex still showed higher P adsorption than the crystalline GE-HA complex. The decreased P adsorption observed might be attributed to changes of the FeO surface charges caused by OM association. The dependence of P adsorption on the specific surface area of adsorbents suggests that the FeO component in the complexes is still the main contributor for the adsorption surfaces. The P adsorptions on FeO-HA complexes decreased with increasing initial pH or decreasing initial ionic strength. A strong dependence of P adsorption on ionic strength and pH may demonstrate that outer-sphere complexes between the OM component on the surface and P possibly coexist with inner-sphere surface complexes between the FeO component and P. Therefore, previous over-emphasis on the contributions of original minerals to P immobilization possibly over-estimates the P loading capacity of soils, especially in humic-rich areas. Copyright © 2015. Published by Elsevier B.V.

  6. Adsorption kinetics of NO on ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC)

    NASA Astrophysics Data System (ADS)

    Chen, Jinghuan; Cao, Feifei; Chen, Songze; Ni, Mingjiang; Gao, Xiang; Cen, Kefa

    2014-10-01

    Ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC) were prepared using evaporation-induced self-assembly (EISA) method and used to adsorb NO. N2 sorption, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to confirm their structures. The results showed that the ordered and uniform structures were successfully synthesized and with the introduction of cerium pore properties were not significantly changed. The NO adsorption capacity of OMC was two times larger than that of activated carbon (AC). With the introduction of cerium both the adsorption capacity and the adsorption rate were improved. The effects of residence time and oxygen concentration on NO adsorption were also investigated. Oxygen played an important role in the NO adsorption (especially in the form of chemisorption) and residence time had small influence on the NO adsorption capacity. The NO adsorption kinetics was analyzed using pseudo-first-order, pseudo-second-order, Elovich equation and intraparticle diffusion models. The results indicated that the NO adsorption process can be divided into rapid adsorption period, slow adsorption period, and equilibrium adsorption period. The pseudo-second-order model was the most suitable model for NO adsorption on OMC and Ce-OMC. The rate controlling step was the intraparticle diffusion together with the adsorption reaction.

  7. Study on kinetics of adsorption of humic acid modified by ferric chloride on U(VI)

    NASA Astrophysics Data System (ADS)

    Zhang, Y. Y.; Lv, J. W.; Song, Y.; Dong, X. J.; Fang, Q.

    2017-11-01

    In order to reveal the adsorption mechanism of the ferric chloride modified humic acid on uranium, the influence of pH value and contact time of adsorption on uranium was studied through a series of batch experiments. Meanwhile, the adsorption kinetics was analyzed with pseudo-first order kinetic model and pseudo-second order kinetic model. The results show that adsorption is affected by the pH value of the solution and by contract time, and the best condition for adsorption on uranium is at pH=5 and the adsorption equilibrium time is about 80 min. Kinetics of HA-Fe adsorption on uranium accords with pseudo-second order kinetic model. The adsorption is mainly chemical adsorption, and complexes were produced by the reaction between uranium ions and the functional groups on the surface of HA-Fe, which can provide reference for further study of humic acid effecting on the migration of U(VI) in soil.

  8. Adsorption of Rh(III) complexes from chloride solutions obtained by leaching chlorinated spent automotive catalysts on ion-exchange resin Diaion WA21J.

    PubMed

    Shen, Shaobo; Pan, Tonglin; Liu, Xinqiang; Yuan, Lei; Wang, Jinchao; Zhang, Yongjian; Guo, Zhanchen

    2010-07-15

    It was found that Rh, Pd and Pt contained in the spent ceramic automotive catalysts could be effectively extracted by dry chlorination with chlorine. In order to concentrate Rh(III) ions contained in the chloride solutions obtained, thermodynamic and kinetics studies for adsorption of Rh(III) complexes from the chloride solutions on an anionic exchange resin Diaion WA21J were carried out. Rh, Pd, Pt, Al, Fe, Si, Zn and Pb from the chloride solution could be adsorbed on the resin. The distribution coefficients (K(d)) of Rh(III) decreased with the increase in initial Rh(III) concentration or in adsorption temperature. The isothermal adsorption of Rh(III) was found to fit Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich models under the adsorption conditions. The maximum monolayer adsorption capacities Q(max) based on Langmuir adsorption isotherms were 6.39, 6.61 and 5.81 mg/g for temperatures 18, 28 and 40 degrees C, respectively. The apparent adsorption energy of Rh was about -7.6 kJ/mol and thus Rh(III) adsorption was a physical type. The experimental data obtained could be better simulated by pseudo-first-order kinetic model and the activation energy obtained was 6.54 J/mol. The adsorption rate of Rh(III) was controlled by intraparticle diffusion in most of time of adsorption process. 2010 Elsevier B.V. All rights reserved.

  9. [Adsorptive Stabilization of Soil Cr (VI) Using HDTMA Modified Montmorillonite].

    PubMed

    2016-03-15

    A series of organo-montomorillonites were prepared using Na-montomorillonite and hexadecyl trimethyl ammonium bromide (HDTMA). The organo-montomorillonites were then investigated for the remediation of Cr(VI) contaminated soils. FT-IR, XRD, SEM and N2 -BET, CEC, Zeta potential measurement were conducted to understand the structural changes of montmorillonites as different amounts of HDTMAs were added as modifier. The characterization results indicated that the clay interlayer spacing distance increased from 1. 25 nm to 2. 13 nm, the clay surface roughness decreased, the clay surface area reduced from 38.91 m² · g⁻¹ to 0.42 m² · g⁻¹, the clay exchangeable cation amount reduced from 62 cmol · kg⁻¹ to 9.9 cmol · kg⁻¹ and the clay surface charge changed from -29.1 mV to 5.59 mV as the dosage of HDTMA in montmorillonite was increased. The TCLP (toxicity characteristic leaching procedure) was used to evaluate the leachate toxicity of Cr(VI). The effects of the initial soil Cr(VI) concentration, montmorillonites dosage, reaction time and HDTMA modification amount were investigated, respectively. The results revealed that modification of montmorillonites would manifest an attenuated physical adsorptive effect and an enhanced electrostatic adsorptive effect on Cr(VI), suggesting electrostatic effect was the major force that resulted in improved Cr(VI) adsorption onto HDTMA modified montmorillonites.

  10. Chemical functionalization of diatom silica microparticles for adsorption of gold (III) ions.

    PubMed

    Yu, Yang; Addai-Mensah, Jonas; Losic, Dusan

    2011-12-01

    Diatom silica microparticles from natural diatomaceous earth (DE) silica have been functionalized with 3-mercaptopropyltrimethoxysilane (MPTMS) and their application for adsorption of gold (III) ions from aqueous solutions is demonstrated. Fourier transform infrared spectroscopy (FTIR) and X-ray Photoelectron spectroscopy (XPS) analyses of the MPTMS modified diatom microparticles revealed that the silane layer with functional group (-SH) was successfully introduced to the diatom surface. The adsorption study of Au(III) ions using MPTMS-DE indicated that the process depends on initial gold (III) concentration and pH showing maximum adsorption capacity at pH = 3. The Au(III) adsorption kinetics results showed that the adsorption was very fast and followed a pseudo-second-order reaction model. The Langmuir model was used to provide a sound mechanistic basis for the theoretical of the adsorption equilibrium data. Gold recovery from MPTMS-DE structures was also investigated by using acidified thiourea solution and found to be high (> 95%). These results show that chemically modified DE microparticles can be used as a new, cost effective and environmentally benign adsorbent suitable for adsorption of gold metal ions from aqueous solutions.

  11. Preparation of novel multi-walled carbon nanotubes nanocomposite adsorbent via RAFT technique for the adsorption of toxic copper ions.

    PubMed

    Hosseinzadeh, Hossein; Pashaei, Shahryar; Hosseinzadeh, Soleyman; Khodaparast, Zahra; Ramin, Sonia; Saadat, Younes

    2018-05-31

    In the present work, polymer-coated multiwalled carbon nanotube (MWCNT) was prepared via RAFT method. First, a novel trithiocarbonate-based RAFT agent was prepared attached chemically into the surface of MWCNT. In addition, the RAFT co-polymerization of acrylic acid and acrylamide monomers was conducted through the prepared RAFT agent. In the next age, the surface morphology and chemical properties of the prepared components were fully examined by using FTIR, 1 HNMR, SEM, TEM, XRD and TGA/DTG techniques. Finally, the modified MWCNT composite was employed as an excellent adsorbent for the adsorption of copper (II) ions. The results indicated that ion adsorption basically relies on adsorbing time, solution pH, initial copper concentration, and adsorbent dosage. Further, the adsorption kinetics and isotherm analysis demonstrated that the adsorption mode was fitted with the pseudo-second-order and Langmuir isotherm models, respectively. Based on the results of thermodynamic study, the ion adsorption process was endothermic and spontaneous. Finally, based on the experimental results, the surface functionalized MWCNT with hydrophilic groups could be successfully used as a promising selective adsorbent material in wastewater treatment. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Adsorption properties of congo red from aqueous solution onto N,O-carboxymethyl-chitosan.

    PubMed

    Wang, Li; Wang, Aiqin

    2008-03-01

    N,O-carboxymethyl-chitosans (N,O-CMC) with different degree of substitution (DS) were synthesized under heterogeneous conditions by controlling the reaction temperature. The factors influencing adsorption capacity of N,O-CMC such as the DS of N,O-CMC, initial pH value of the dye solution and adsorption temperature for anionic dye congo red (CR) were investigated. Compared with chitosan (78.90 mg/g), N,O-CMC with the DS of 0.35 exhibited much higher adsorption capacity (330.62 mg/g) for CR at the same adsorption conditions. The adsorption kinetics and isotherms showed that the sorption processes were better fitted by pseudo-second-order equation and the Langmuir equation, respectively. The adsorption mechanism of N,O-CMC was also discussed by means of IR and XPS spectra. The results in this study indicated that N,O-CMC was an attractive candidate for removing CR from the dye wastewater.

  13. Water adsorption on goethite: Application of multilayer adsorption models

    NASA Astrophysics Data System (ADS)

    Hatch, C. D.; Tumminello, R.; Meredith, R.

    2016-12-01

    Adsorbed water on the surface of atmospheric mineral dust has recently been shown to significantly affect the ability of mineral dust aerosol to act as cloud condensation nuclei. We have studied water adsorption as a function of relative humidity (RH) on goethite (α-FeO(OH)), a common component of atmospheric mineral dust. The goethite surface area and particle size was determined using BET analysis and with N2 as an adsorbate and scanning electron microscopy, respectively. Water adsorption on the sample was monitored using horizontal attenuated total reflectance Fourier transform infrared (HATR-FTIR) spectroscopy equipped with a flow cell. Water content was determined using Beer's law and the optical constants for bulk water. The results were analyzed using Type II adsorption isotherms to model multilayer adsorption, including BET (Brunauer, Emmet and Teller), FHH (Frenkel, Halsey and Hill) and Freundlich. BET fits to experimental data provide parameters of monolayer coverage, while the FHH and Freundlich isotherms provide insights into multilayer adsorption mechanisms. Results indicate that goethite contains 5% H2O by mass at 50% RH, which increases to 12% by mass at 90% RH. Adsorption parameters and experimental results will be presented.

  14. Fabrication of novel metal ion imprinted xanthan gum-layered double hydroxide nanocomposite for adsorption of rare earth elements.

    PubMed

    Iftekhar, Sidra; Srivastava, Varsha; Hammouda, Samia Ben; Sillanpää, Mika

    2018-08-15

    The work focus to enhance the properties of xanthan gum (XG) by anchoring metal ions (Fe, Zr) and encapsulating inorganic matrix (M@XG-ZA). The fabricated nanocomposite was characterized by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR), surface area (BET) and zeta potential analysis. The adsorption of Sc, Nd, Tm and Yb was investigated after screening of synthesized materials in detail to understand the influence of pH, contact time, temperature and initial REE (rare earth element) concentration both in single and multicomponent system via batch adsorption. The adsorption mechanism was verified by FTIR, SEM and elemental mapping. The SEM images of Zr@XG-ZA demonstrate scutes structure, which disappeared after adsorption of REEs. The maximum adsorption capacities were 132.30, 14.01, 18.15 and 25.73 mg/g for Sc, Nd, Tm and Yb, respectively. The adsorption efficiency over Zr@XG-ZA in multicomponent system was higher than single system and the REEs followed the order: Sc > Yb > Tm > Nd. The Zr@XG-ZA demonstrate good adsorption behavior for REEs up to five cycles and then it can be used as photocatalyst for the degradation of tetracycline. Thus, the work adds a new insight to design and preparation of efficient bifunctional adsorbents from sustainable materials for water purification. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Adsorption characteristics of UO(2)(2+) and Th(4+) ions from simulated radioactive solutions onto chitosan/clinoptilolite sorbents.

    PubMed

    Humelnicu, Doina; Dinu, Maria Valentina; Drăgan, Ecaterina Stela

    2011-01-15

    Adsorption features of UO(2)(2+) and Th(4+) ions from simulated radioactive solutions onto a novel chitosan/clinoptilolite (CS/CPL) composite as beads have been investigated compared with chitosan cross-linked with epichlorohydrin. The effects of contact time, the initial metal ion concentration, sorbent mass and temperature on the adsorption capacity of the CS-based sorbents were investigated. The adsorption kinetics was well described by the pseudo-second order equation, and the adsorption isotherms were better fitted by the Sips model. The maximum experimental adsorption capacities were 328.32 mg Th(4+)/g composite, and 408.62 mg UO(2)(2+)/g composite. The overall adsorption tendency of CS/CPL composite toward UO(2)(2+) and Th(4+) radiocations in the presence of Cu(2+), Fe(2+) and Al(3+), under competitive conditions, followed the order: Cu(2+)>UO(2)(2+)>Fe(2+)>Al(3+), and Cu(2+)>Th(4+)>Fe(2+)>Al(3+), respectively. The negative values of Gibbs free energy of adsorption indicated the spontaneity of the adsorption of radioactive ions on both the CS/CPL composite and the cross-linked CS. The desorption level of UO(2)(2+) from the composite CS/CPL, by using 0.1M Na(2)CO(3), was around 92%, and that of Th(4+) ions, performed by 0.1M HCl, was around 85%, both values being higher than the desorption level of radiocations from the cross-linked CS, which were 89% and 83%, respectively. Copyright © 2010 Elsevier B.V. All rights reserved.

  16. Volatile organic compound adsorption in a gas-solid fluidized bed.

    PubMed

    Ng, Y L; Yan, R; Tsen, L T S; Yong, L C; Liu, M; Liang, D T

    2004-01-01

    Fluidization finds many process applications in the areas of catalytic reactions, drying, coating, combustion, gasification and microbial culturing. This work aims to compare the dynamic adsorption characteristics and adsorption rates in a bubbling fluidized bed and a fixed bed at the same gas flow-rate, gas residence time and bed height. Adsorption with 520 ppm methanol and 489 ppm isobutane by the ZSM-5 zeolite of different particle size in the two beds enabled the differentiation of the adsorption characteristics and rates due to bed type, intraparticle mass transfer and adsorbate-adsorbent interaction. Adsorption of isobutane by the more commonly used activated carbon provided the comparison of adsorption between the two adsorbent types. With the same gas residence time of 0.79 seconds in both the bubbling bed and fixed bed of the same bed size of 40 mm diameter and 48 mm height, the experimental results showed a higher rate of adsorption in the bubbling bed as compared to the fixed bed. Intraparticle mass transfer and adsorbent-adsorbate interaction played significant roles in affecting the rate of adsorption, with intraparticle mass transfer being more dominant. The bubbling bed was observed to have a steeper decline in adsorption rate with respect to increasing outlet concentration compared to the fixed bed. The adsorption capacities of zeolite for the adsorbates studied were comparatively similar in both beds; fluidizing, and using smaller particles in the bubbling bed did not increase the adsorption capacity of the ZSM-5 zeolite. The adsorption capacity of activated carbon for isobutane was much higher than the ZSM-5 zeolite for isobutane, although at a lower adsorption rate. Fourier transform infra-red (FTIR) spectroscopy was used as an analytical tool for the quantification of gas concentration. Calibration was done using a series of standards prepared by in situ dilution with nitrogen gas, based on the ideal gas law and relating partial pressure to gas

  17. Multilayer adsorption of Cu(II) and Cd(II) over Brazilian Orchid Tree (Pata-de-vaca) and its adsorptive properties

    NASA Astrophysics Data System (ADS)

    Jorgetto, Alexandre de O.; da Silva, Adrielli C. P.; Wondracek, Marcos H. P.; Silva, Rafael I. V.; Velini, Edivaldo D.; Saeki, Margarida J.; Pedrosa, Valber A.; Castro, Gustavo R.

    2015-08-01

    Through very simple and inexpensive processes, pata-de-vaca leaves were turned into a powder and applied as an adsorbent for the uptake of Cu(II) and Cd(II) from water. The material was characterized through SEM, EDX, FTIR and surface area measurement. The material had its point of zero charge determined (5.24), and its adsorption capacity was evaluated as a function of time, pH and metal concentration. The material presented fast adsorption kinetics, reaching adsorption equilibrium in less than 5 min and it had a good correlation with the pseudo-second order kinetic model. Optimum pH for the adsorption of Cu(II) and Cd(II) were found to be in the range from 4 to 5, approximately. In the experiment as a function of the analyte concentration, analogously to gas adsorption, the material presented a type II isotherm, indicating the formation of multilayers for both species. Such behavior was explained with basis in the alternation between cations and anions over the material's surface, and the maximum adsorption capacity, considering the formation of the multilayers were found to be 0.238 mmol L-1 for Cu(II) and 0.113 mmol L-1 for Cd(II).

  18. Adsorption behaviour of methylene blue onto Jordanian diatomite: a kinetic study.

    PubMed

    Al-Ghouti, Mohammad A; Khraisheh, Majeda A M; Ahmad, Mohammad N M; Allen, Stephen

    2009-06-15

    The effect of initial concentration, particle size, mass of the adsorbent, pH and agitation speed on adsorption behaviour of methylene blue (MB) onto Jordanian diatomite has been investigated. The maximum adsorption capacity, q, increased from 75 to 105 mg/g when pH of the dye solution increased from 4 to 11. It is clear that the ionisable charge sites on the diatomite surface increased when pH increased from 4 to 11. When the solution pH was above the pH(ZPC), the diatomite surface had a negative charge, while at low pH (pH<5.4) it has a positive charge. The adsorption capacity increased from 88.6 to 143.3mg/g as the initial MB concentrations increased from 89.6 to 225.2mg/dm(3). The experimental results were also applied to the pseudo-first and -second order kinetic models. It is noticed that the whole experimental data of MB adsorption onto diatomite did not follow the pseudo-first order model and had low correlation coefficients (R(2)<0.3). The calculated adsorption capacity, q(e,cal), values obtained from pseudo-first order kinetic model did not give acceptable values, q(e,exp.) The maximum uptake capacity seems to be independent of the particle size of the diatomite when the particle size distribution is less than 250-500 microm. While at larger particle size 250-500 microm, the maximum uptake capacity was dependent on the particle size. It would imply that the MB adsorption is limited by the external surface and that intraparticle diffusion is reduced. The effect of the agitation speeds on the removal of MB from aqueous solution using the diatomite is quite low. The MB removal increased from 43 to 100% when mass of the diatomite increased from 0.3 to 1.7 g.

  19. Efficiently mapping structure-property relationships of gas adsorption in porous materials: application to Xe adsorption.

    PubMed

    Kaija, A R; Wilmer, C E

    2017-09-08

    Designing better porous materials for gas storage or separations applications frequently leverages known structure-property relationships. Reliable structure-property relationships, however, only reveal themselves when adsorption data on many porous materials are aggregated and compared. Gathering enough data experimentally is prohibitively time consuming, and even approaches based on large-scale computer simulations face challenges. Brute force computational screening approaches that do not efficiently sample the space of porous materials may be ineffective when the number of possible materials is too large. Here we describe a general and efficient computational method for mapping structure-property spaces of porous materials that can be useful for adsorption related applications. We describe an algorithm that generates random porous "pseudomaterials", for which we calculate structural characteristics (e.g., surface area, pore size and void fraction) and also gas adsorption properties via molecular simulations. Here we chose to focus on void fraction and Xe adsorption at 1 bar, 5 bar, and 10 bar. The algorithm then identifies pseudomaterials with rare combinations of void fraction and Xe adsorption and mutates them to generate new pseudomaterials, thereby selectively adding data only to those parts of the structure-property map that are the least explored. Use of this method can help guide the design of new porous materials for gas storage and separations applications in the future.

  20. Adsorption of hexavalent chromium onto sisal pulp/polypyrrole composites

    NASA Astrophysics Data System (ADS)

    Tan, Y. Y.; Wei, C.; Gong, Y. Y.; Du, L. L.

    2017-02-01

    Sisal pulp/polypyrrole composites(SP/PPy) utilized for the removal of hexavalent chromium [Cr(VI)] from wastewater, were prepared via in-situ chemical oxidation polymerization approach. The structure and morphology of the SP/PPy were analyzed by polarizing optical microscopy (POM), field-emission scanning electron microscopy (SEM)), Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), the results indicated SP could be efficient dispersion of PPy. The hexavalent chromium adsorption results indicate adsorption capacity of the SP/PPy were dependent on the initial pH, with an optimum pH of 2.0. The sorption kinetic data fitted well to the pseudo-second order model and isotherm data fitted well to the Langmuir isotherm model. The maximum adsorption capacity determined from the Langmuir isotherm is 336.70 mg/g at 25° C.

  1. Adsorptive removal of malachite green from aqueous solutions by almond gum: Kinetic study and equilibrium isotherms.

    PubMed

    Bouaziz, Fatma; Koubaa, Mohamed; Kallel, Fatma; Ghorbel, Rhoudha Ellouz; Chaabouni, Semia Ellouz

    2017-12-01

    This work aimed at investigating the potential of almond gum as low cost adsorbent for the removal of the cationic dye; malachite green from aqueous solutions. Almond gum was first analyzed by scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR), and then the adsorption behavior was studied in batch system. The effects of the adsorption parameters (adsorbent dose, pH, contact time, particle size, initial dye concentration, temperature and agitation) on the dye removal have been studied. Adsorption equilibrium and isotherms were evaluated depending on temperature using the isotherms of Freundlich, Langmuir, and Tempkin. The obtained result showed that both Langmuir and Freundlich models were adapted to study the dye sorption. The maximum adsorption capacities were equal to 172.41mg/g, 181.81mg/g, and 196.07mg/g at 303.16K, 313.16K, and 323.16K, respectively. The kinetics of sorption were following the pseudo-second order model. The thermodynamic changes in enthalpy (ΔH), entropy (ΔS), and free energy (ΔG) indicated that the adsorption of malachite green at the surface of almond gum is endothermic and occurs spontaneously. Desorption experiments were conducted to regenerate almond gum, showing great desorption capacity when using HCl at pH 2. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. 42 CFR 405.922 - Time frame for processing initial determinations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Time frame for processing initial determinations. 405.922 Section 405.922 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH... § 405.922 Time frame for processing initial determinations. The contractor issues initial determinations...

  3. Cr(VI) Adsorption on Red Mud Modified by Lanthanum: Performance, Kinetics and Mechanisms

    PubMed Central

    Cui, You-Wei; Li, Jie; Du, Zhao-Fu; Peng, Yong-Zhen

    2016-01-01

    Water pollution caused by the highly toxic metal hexavalent chromium (Cr(VI)) creates significant human health and ecological risks. In this study, a novel adsorbent was used to treat Cr(VI)-containing wastewater; the adsorbent was prepared using red mud (RM) generated from the alumina production industry and the rare earth element lanthanum. This study explored adsorption performance, kinetics, and mechanisms. Results showed that the adsorption kinetics of the RM modified by lanthanum (La-RM), followed the pseudo-second-order model, with a rapid adsorption rate. Cr(VI) adsorption was positively associated with the absorbent dose, pH, temperature, and initial Cr(VI) concentration; coexisting anions had little impact. The maximum Cr(VI) adsorption capacity was 17.35 mg/g. Cr(VI) adsorption on La-RM was a mono-layer adsorption pattern, following the Langmuir isotherm model. Thermodynamic parameters showed the adsorption was spontaneous and endothermic. The adsorption of Cr(VI) on La-RM occurred as a result of LaOCl formation on the RM surface, which in turn further reacted with Cr(VI) in the wastewater. This study highlighted a method for converting industrial waste into a valuable material for wastewater treatment. The novel absorbent could be used as a potential adsorbent for treating Cr(VI)-contaminating wastewater, due to its cost-effectiveness and high adsorption capability. PMID:27658113

  4. Pb(II) adsorption by biomass from chemically modified aquatic macrophytes, Salvinia sp. and Pistia stratiotes.

    PubMed

    de Moraes Ferreira, Rachel; de Souza, Michael Douglas Peçanha; Takase, Iracema; de Araujo Stapelfeldt, Danielle Marques

    2016-01-01

    This study used two biosorbents obtained from the aquatic plants Salvinia sp. and Pistia stratiotes to establish a sustainable and alternative treatment for industrial wastewater and other water bodies that contain Pb(II). The biosorbent named Salvinia with NaOH (SOH) was obtained from Salvinia sp., and Salvinia and Pistia mixture with NaOH (SPOH) was obtained from a mixture of the two plants in a 1:1 ratio. The biosorbents were characterized by zeta potential, infrared (IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy and Boehm titration. The results of Boehm titration and IR analysis indicated the presence of basic functional groups, whereas those of SEM analysis indicated that the biosorbents have a structure conducive to adsorption. Batch adsorption experiments were performed to observe the effects of pH, contact time, initial lead concentration and temperature on the metal removal process. The results revealed that the biosorbents efficiently removed Pb(II) from aqueous solutions, with a maximum observed adsorption capacity (saturation limits, qmax) of 202 mg g(-1) and 210.1 mg g(-1) for SPOH and SOH, respectively. The Freundlich, Langmuir and Dubinin-Radushkevich models were applied to the data; these biosorbent studies did not satisfactorily adjust to either of the models, but the information obtained helped us understand the adsorption mechanism.

  5. Effects of resident water and non-equilibrium adsorption on the primary and enhanced coalbed methane gas recovery

    NASA Astrophysics Data System (ADS)

    Jahediesfanjani, Hossein

    The major part of the gas in coalbed methane and shale gas reservoirs is stored as the adsorbed gas in the coal and organic materials of the black shale internal surfaces. The sorption sites in both reservoirs are composed of several macropores that contain very small pore sizes. Therefore, the adsorption/desorption is very slow process and follows a non-equilibrium trend. The time-dependency of the sorption process is further affected by the reservoir resident water. Water can diffuse into the matrix and adsorption sites, plug the pores and affect the reservoir gas production. This study presents an experimental and theoretical procedure to investigate the effects of the resident water and time-dependency of the sorption process on coalbed and shale gas primary and enhanced recovery by simultaneous CO 2/N2 injection. Series of the experiments are conducted to construct both equilibrium and non-equilibrium single and multi-component isotherms with the presence of water. A novel and rapid data interpretation technique is developed based on the nonequilibrium adsorption/desorption thermodynamics, mass conservation law, and volume filling adsorption theory. The developed technique is implemented to construct both equilibrium and non-equilibrium multi-component multi-phase isotherms from the early time experimental measurements. The non-equilibrium isotherms are incorporated in the coalbed methane/shale gas reservoir simulations to account for the time-dependency of the sorption process. The experimental results indicate that the presence of water in the sorption system reduces both carbon dioxide and nitrogen adsorption rates. Reduction in the adsorption rate for carbon dioxide is more than nitrogen. The results also indicate that the resident water reduces the adsorption ability of low rank coals more than high rank ones. The results of the multi-component sorption tests indicate that increasing the initial mole fraction of the nitrogen gas in the injected CO2/N2

  6. Comparison of adsorption and photo-Fenton processes for phenol and paracetamol removing from aqueous solutions: Single and binary systems

    NASA Astrophysics Data System (ADS)

    Rad, Leila Roshanfekr; Haririan, Ismaeil; Divsar, Faten

    2015-02-01

    In the present study, adsorption and photo-Fenton processes have been compared for the removal of phenol and paracetamol from aqueous solutions in a single and binary systems. NaX nanozeolites and cobalt ferrite nanoparticles were used during adsorption and photo-Fenton processes, respectively. Both nanoparticles were synthesized using microwave heating method. The synthesized nanoparticles were characterized using powder X-ray diffraction (XRD) and scanning electronic microscopy (SEM) analysis. Based on results, more than 99% removing percentages of phenol and paracetamol were obtained during photo-Fenton process at initial concentrations of 10, 20, 50, 100 and 200 mg/L of phenol and paracetamol. Moreover, the complete removing of phenol and paracetamol was only achieved at lower initial concentrations than 10 mg/L for phenol and paracetamol during adsorption process. The results showed a significant dependence of the phenol and paracetamol removing on the initial concentrations of phenol and paracetamol for selection of process. The photo-Fenton process could be considered an alternative method in higher initial concentrations of phenol and paracetamol. However, the adsorption process due to economical issue was preferred for phenol and paracetamol removing at lower initial concentrations. The kinetic data of photo-Fenton and adsorption processes were well described using first-order and pseudo-second-order kinetic models. The results of phenol and paracetamol removing in a binary system confirmed the obtained results of single removing of phenol and paracetamol in selection of process.

  7. Adsorption Refrigeration System

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Kai; Vineyard, Edward Allan

    Adsorption refrigeration is an environmentally friendly cooling technology which could be driven by recovered waste heat or low-grade heat such as solar energy. In comparison with absorption system, an adsorption system has no problems such as corrosion at high temperature and salt crystallization. In comparison with vapor compression refrigeration system, it has the advantages of simple control, no moving parts and less noise. This paper introduces the basic theory of adsorption cycle as well as the advanced adsorption cycles such as heat and mass recovery cycle, thermal wave cycle and convection thermal wave cycle. The types, characteristics, advantages and drawbacksmore » of different adsorbents used in adsorption refrigeration systems are also summarized. This article will increase the awareness of this emerging cooling technology among the HVAC engineers and help them select appropriate adsorption systems in energy-efficient building design.« less

  8. Preparation of Chitosan Coated Magnetic Hydroxyapatite Nanoparticles and Application for Adsorption of Reactive Blue 19 and Ni2+ Ions

    PubMed Central

    Nguyen, Van Cuong; Pho, Quoc Hue

    2014-01-01

    An adsorbent called chitosan coated magnetic hydroxyapatite nanoparticles (CS-MHAP) was prepared with the purpose of improvement for the removal of Ni2+ ions and textile dye by coprecipitation. Structure and properties of CS-MHAP were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM). Weight percent of chitosan was investigated by thermal gravimetric analysis (TGA). The prepared CS-MHAP presents a significant improvement on the removal efficiency of Ni2+ ions and reactive blue 19 dye (RB19) in comparison with chitosan and magnetic hydroxyapatite nanoparticles. Moreover, the adsorption capacities were affected by several parameters such as contact time, initial concentration, adsorbent dosage, and initial pH. Interestingly, the prepared adsorbent could be easily recycled from an aqueous solution by an external magnet and reused for adsorption with high removal efficiency. PMID:24592158

  9. Selenium isotope fractionation during adsorption onto the modified clay minerals

    NASA Astrophysics Data System (ADS)

    Xu, W.; Jianming, Z.; Tan, D.; Qin, H.

    2016-12-01

    Currently, Selenium (Se) isotopes have been used as a paleoenvironmental proxy to trace Se evolution in Ancient Ocean. And many researchers considered the variation of Se isotopes in nature mainly result from the reduction of Se oxyanion, while Se isotope fractionation during adsorption onto minerals was rarely reported. Therefore, based on the previous studies [1, 2], we used three common clay minerals in supergene environment: montmorillonite, illite and kaolinite as an adsorbent to study Se isotope fractionation during adsorption. Before doing adsorption experiments, the adsorbent were modified as Na-clay minerals to remove the possibility of interference of Ca2+, Fe3+, Fe2+ as well as organic matters. A batch adsorption experiments were carried out at room temperature (23 ±2 °) under N2 atmosphere, initial Se concentration (SeO32-/ SeO42-) was respectively 200ng and 100ng, the solution ionic strength was 0.1mol/L NaCl; the ratio of liquid to solid is 2g / L, and pH = 5. Experimental results showed that adsorption reached a steady state during 48h, and the maximum adsorption for SeO32- was larger than SeO42-. The isotope data showed that SeO42- adsorbed onto three clay minerals didn't present obvious Se isotope fractionation, generally δ82/78Se is less than 0.1 ‰. Meanwhile, SeO32- during adsorption process also didn't show the significant fractionation, less than 0.3 ‰. However, interestingly, for SeO32- the δ82/78Se values of solution during adsorption onto kaolinite underwent a process of increasing by 0.5‰ compared to the initial solution and then decreasing to 0.3‰. We speculated the reason may not be related to the surface charge of the clay minerals, but mostly with the layered structure of clay minerals. Montmorillonite and illite are 2: 1; kaolinite is 1: 1 layered structure. The different layered structure may influence the isotope fraction between Se oxyanions and clay minerals. These still needs further and more experiments to definitely

  10. Immobilization of Candida antarctica lipase B by adsorption to green coconut fiber.

    PubMed

    Brígida, Ana I S; Pinheiro, Alvaro D T; Ferreira, Andrea L O; Gonçalves, Luciana R B

    2008-03-01

    An agroindustrial residue, green coconut fiber, was evaluated as support for immobilization of Candida antarctica type B (CALB) lipase by physical adsorption. The influence of several parameters, such as contact time, amount of enzyme offered to immobilization, and pH of lipase solution was analyzed to select a suitable immobilization protocol. Kinetic constants of soluble and immobilized lipases were assayed. Thermal and operational stability of the immobilized enzyme, obtained after 2 h of contact between coconut fiber and enzyme solution, containing 40 U/ml in 25 mM sodium phosphate buffer pH 7, were determined. CALB immobilization by adsorption on coconut fiber promoted an increase in thermal stability at 50 and 60 degrees C, as half-lives (t (1/2)) of the immobilized enzyme were, respectively, 2- and 92-fold higher than the ones for soluble enzyme. Furthermore, operational stabilities of methyl butyrate hydrolysis and butyl butyrate synthesis were evaluated. After the third cycle of methyl butyrate hydrolysis, it retained less than 50% of the initial activity, while Novozyme 435 retained more than 70% after the tenth cycle. However, in the synthesis of butyl butyrate, CALB immobilized on coconut fiber showed a good operational stability when compared to Novozyme 435, retaining 80% of its initial activity after the sixth cycle of reaction.

  11. Immobilization of Candida antarctica Lipase B by Adsorption to Green Coconut Fiber

    NASA Astrophysics Data System (ADS)

    Brígida, Ana I. S.; Pinheiro, Álvaro D. T.; Ferreira, Andrea L. O.; Gonçalves, Luciana R. B.

    An agroindustrial residue, green coconut fiber, was evaluated as support for immobilization of Candida antarctica type B (CALB) lipase by physical adsorption. The influence of several parameters, such as contact time, amount of enzyme offered to immobilization, and pH of lipase solution was analyzed to select a suitable immobilization protocol. Kinetic constants of soluble and immobilized lipases were assayed. Thermal and operational stability of the immobilized enzyme, obtained after 2 h of contact between coconut fiber and enzyme solution, containing 40 U/ml in 25 mM sodium phosphate buffer pH 7, were determined. CALB immobilization by adsorption on coconut fiber promoted an increase in thermal stability at 50 and 60 °C, as half-lives (t 1/2) of the immobilized enzyme were, respectively, 2- and 92-fold higher than the ones for soluble enzyme. Furthermore, operational stabilities of methyl butyrate hydrolysis and butyl butyrate synthesis were evaluated. After the third cycle of methyl butyrate hydrolysis, it retained less than 50% of the initial activity, while Novozyme 435 retained more than 70% after the tenth cycle. However, in the synthesis of butyl butyrate, CALB immobilized on coconut fiber showed a good operational stability when compared to Novozyme 435, retaining 80% of its initial activity after the sixth cycle of reaction.

  12. Adsorption and desorption properties of macroporous resins for anthocyanins from the calyx extract of roselle (Hibiscus sabdariffa L.).

    PubMed

    Chang, Xiu-Lian; Wang, Dong; Chen, Bi-Yun; Feng, Yong-Mei; Wen, Shao-Hong; Zhan, Peng-Yuan

    2012-03-07

    Adsorption of roselle anthocynins, a natural pigment, onto various macroporous resins was optimized to develop a simple and efficient process for industrial separation and purification of roselle anthocyanins. Nine different macroporous resins (AB-8, X-5, HPD-100, SP-207, XAD-4, LS-305A, DM-21, LS-610B, and LS-305) were evaluated for the adsorption properties of the anthocyanins extracted from the calyx extract of Hibiscus sabdariffa L. The influences of phase contact time, solution pH, initial anthocyanin concentration, and ethanol concentration with different citric acid amounts were studied by the static adsorption/desorption method. The adsorption isotherm data were fitted well to the Langmuir isotherm, and according to this model, LS-610B and LS-305 exhibited the highest monolayer sorption capacities of 31.95 and 38.16 mg/g, respectively. The kinetic data were modeled using pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations. The experimental data were well described by the pseudo-second-order kinetic model. Continuous column adsorption-regeneration cycles indicated negligible capacity loss of LS-305 during operation. The overall yield of pigment product was 49.6 mg/g dried calyces. The content of roselle anthocynins in the pigment product was 4.85%.

  13. Adsorption of Cd2+ ions on plant mediated SnO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Haq, Sirajul; Rehman, Wajid; Waseem, Muhammad; Shahid, Muhammad; Mahfooz-ur-Rehman; Hussain Shah, Khizar; Nawaz, Mohsan

    2016-10-01

    Plant mediated SnO2 nanoparticles were synthesized by using SnCl4.5H2O as a precursor material. The nanoparticles were then characterized for BET surface area measurements, energy dispersive x-rays (EDX), scanning electron microscopy (SEM), UV-vis diffuse reflectance (DRS) spectra and x-rays diffraction (XRD) analysis. The successful synthesis of SnO2 nanoparticles was confirmed by EDX analysis. The particle sizes were in the range 19-27 nm whereas the crystallite size computed from XRD measurement was found to be 19.9 nm. Batch adsorption technique was employed for the removal of Cd2+ ions from aqueous solution. The sorption studies of Cd2+ ions were performed at pHs 4 and 6. The equilibrium concentration of Cd2+ ions was determined by atomic absorption spectrometer (flame mode). The uptake of Cd2+ ions was affected by initial concentration, pH and temperature of the electrolytic solution. It was observed that the adsorption of Cd2+ ions enhanced with increase in the initial concentration of Cd2+ ions whereas a decrease in the percent adsorption was detected. From the thermodynamic parameters, the adsorption process was found spontaneous and endothermic in nature. The n values confirmed 2:1 exchange mechanism between surface protons and Cd2+ ions.

  14. The influence of white and blue silica gels as adsorbents in adsorptive-distillation of ethanol-water mixture

    NASA Astrophysics Data System (ADS)

    Megawati, Jannah, Reni Ainun; Rahayuningtiyas, Indi

    2017-01-01

    This research studied the difference of white and blue silica gels when used as an adsorbent for ethanol purification that is processed via Adsorptive-Distillation (AD) at 1 atm pressure. The effect of process duration to purification process is also recorded and studied to evaluate the performance of designed AD equipment. The experiment was conducted using boiling flask covered with a heating mantle and the temperature was maintained at 78°C. The vapour flowed into the adsorbent column and was condensed using water as a cooling medium. The initial ethanol concentration was 90.8% v/v and volume was 300 mL. Experiment shows that designed AD equipment could be used to purify ethanol. The average vapour velocity was about 39.29 and 45.91 m/s for white and blue silica gels, respectively, which is considered very high. Therefore the saturated adsorption could not be obtained. Highest ethanol concentration achieved using white silica gel is about 96.671% v/v after 50 minutes. Thus AD with white silica gel showed good performance and passed azeotropic point. But AD with blue silica gel showed a different result, the adsorption of blue silica gel failed to break the azeotropic point. The outlet average water concentration for white and blue silica gels is 3.54 and 3.42 mole/L. Based on the weight ratio of adsorbed water per adsorbent, at 55th minutes of time; this ratio of blue silica gel is about 0.053 gwater/gads. The time required by the blue silica to achieve 0.5 wwater-adsorbed/wwater-initial is 45 minutes, and the average outlet water concentration is 3.42 mole/L. Meanwhile, the time required by a white silica to complete 0.5 wwater-adsorbed/wwater-initial is 35 minutes, and the average outlet water level is 3.54 mole/L. Based on the results, the blue silica as an adsorbent for AD of ethanol-water mixture is better than white silica gel.

  15. Selective fibronectin adsorption against albumin and enhanced stem cell attachment on helium atmospheric pressure glow discharge treated titanium

    NASA Astrophysics Data System (ADS)

    Han, Inho; Vagaska, Barbora; Joo Park, Bong; Lee, Mi Hee; Jin Lee, Seung; Park, Jong-Chul

    2011-06-01

    Successful tissue integration of implanted medical devices depends on appropriate initial cellular response. In this study, the effect of helium atmospheric pressure glow discharge (He-APGD) treatment of titanium on selective protein adsorption and the initial attachment processes and focal adhesion formation of osteoprogenitor cells and stem cells were examined. Titanium disks were treated in a self-designed He-APGD system. Initial attachment of MC3T3-E1 mouse pre-osteoblasts and human mesenchymal stem cells (MSCs) was evaluated by MTT assay and plasma membrane staining followed by morphometric analysis. Fibronectin adsorption was investigated by Enzyme-Linked ImmunoSorbant Assay. MSCs cell attachment to treated and non-treated titanium disks coated with different proteins was verified also in serum-free culture. Organization of actin cytoskeleton and focal adhesions was evaluated microscopically. He-APGD treatment effectively modified the titanium surfaces by creating a super-hydrophilic surface, which promoted selectively higher adsorption of fibronectin, a protein of critical importance for cell/biomaterial interaction. In two different types of cells, the He-APGD treatment enhanced the number of attaching cells as well as their attachment area. Moreover, cells had higher organization of actin cytoskeleton and focal adhesions. Faster acceptance of the material by the progenitor cells in the early phases of tissue integration after the implantation may significantly reduce the overall healing time; therefore, titanium treatment with He-APGD seems to be an effective method of surface modification of titanium for improving its tissue inductive properties.

  16. A flow-pulse adsorption-microcalorimetry system for studies of adsorption processes on powder catalysts

    NASA Astrophysics Data System (ADS)

    You, Rui; Li, Zhaorui; Zeng, Hongyu; Huang, Weixin

    2018-06-01

    A pulse chemisorption system combining a Tian-Calvet microcalorimeter (Setaram Sensys EVO 600) and an automated chemisorption apparatus (Micromeritics Autochem II 2920) was established to accurately measure differential adsorption heats of gas molecules' chemisorption on solid surfaces in a flow-pulse mode. Owing to high sensitivity and high degree of automation in a wide range of temperatures from -100 to 600 °C, this coupled system can present adsorption heats as a function of adsorption temperature and adsorbate coverage. The functions of this system were demonstrated by successful measurements of CO adsorption heats on Pd surfaces at various temperatures and also at different CO coverages by varying the CO concentration in the pulse dose. Key parameters, including adsorption amounts, integral adsorption heats, and differential adsorption heats of CO adsorption on a Pd/CeO2 catalyst, were acquired. Our adsorption-microcalorimetry system provides a powerful technique for the investigation of adsorption processes on powder catalysts.

  17. Kinetics of polyelectrolyte adsorption

    NASA Astrophysics Data System (ADS)

    Cohen Stuart, M. A.; Hoogendam, C. W.; de Keizer, A.

    1997-09-01

    The kinetics of polyelectrolyte adsorption has been investigated theoretically. In analogy with Kramers' rate theory for chemical reactions we present a model which is based on the assumption that a polyelectrolyte encounters a barrier in its motion towards an adsorbing surface. The height of the barrier, which is of electrostatic origin, is calculated with a self-consistent-field (SCF) model. The salt concentration strongly affects the height of the barrier. At moderate salt concentrations (0953-8984/9/37/009/img1) equilibrium in the adsorption is attained; at low salt concentration (0953-8984/9/37/009/img2) equilibrium is not reached on the time scale of experiments. The attachment process shows resemblances to the classical DLVO theory.

  18. A study of the kinetics and isotherms for Cr(VI) adsorption in a binary mixture of Cr(VI)-Ni(II) using hierarchical porous carbon obtained from pig bone.

    PubMed

    Li, Chengxian; Huang, Zhe; Huang, Bicheng; Liu, Changfeng; Li, Chengming; Huang, Yaqin

    2014-01-01

    Cr(VI) adsorption in a binary mixture Cr(VI)-Ni(II) using the hierarchical porous carbon prepared from pig bone (HPC) was investigated. The various factors affecting adsorption of Cr(VI) ions from aqueous solutions such as initial concentration, pH, temperature and contact time were analyzed. The results showed excellent efficiency of Cr(VI) adsorption by HPC. The kinetics and isotherms for Cr(VI) adsorption from a binary mixture Cr(VI)-Ni(II) by HPC were studied. The adsorption equilibrium described by the Langmuir isotherm model is better than that described by the Freundlich isotherm model for the binary mixture in this study. The maximum adsorption capacity was reliably found to be as high as 192.68 mg/g in the binary mixture at pH 2. On fitting the experimental data to both pseudo-first- and second-order equations, the regression analysis of the second-order equation gave a better R² value.

  19. [Adsorption of Cu on Core-shell Structured Magnetic Particles: Relationship Between Adsorption Performance and Surface Properties].

    PubMed

    Li, Qiu-mei; Chen, Jing; Li, Hai-ning; Zhang, Xiao-lei; Zhang, Gao-sheng

    2015-12-01

    In order to reveal the relationship between the adsorption performance of adsorbents and their compositions, structure, and surface properties, the core-shell structured Fe₃O₄/MnO2 and Fe-Mn/Mn₂2 magnetic particles were systematically characterized using multiple techniques and their Cu adsorption behaviors as well as mechanism were also investigated in details. It was found that both Fe₃O4 and Fe-Mn had spinel structure and no obvious crystalline phase change was observed after coating with MnO₂. The introduction of Mn might improve the affinity between the core and the shell, and therefore enhanced the amount and distribution uniformity of the MnO₂ coated. Consequently, Fe-Mn/MnO₂ exhibited a higher BET specific surface area and a lower isoelectric point. The results of sorption experiments showed that Fe-Mn had a higher maximal Cu adsorption capacity of 33.7 mg · g⁻¹ at pH 5.5, compared with 17.5 mg · g⁻¹ of Fe₃O4. After coating, the maximal adsorption capacity of Fe-Mn/MnO₂ was increased to 58.2 mg · g⁻¹, which was 2.6 times as high as that of Fe₃O₄/MnO₂ and outperformed the majority of magnetic adsorbents reported in literature. In addition, a specific adsorption of Cu occurred at the surface of Fe₃O₄/MnO₂ or Fe-Mn/MnO₂ through the formation of inner-sphere complexes. In conclusion, the adsorption performance of the magnetic particles was positively related to their compositions, structure, and surface properties.

  20. Kinetics and Equilibrium of Fe3+ Ions Adsorption on Carbon Nanofibers

    NASA Astrophysics Data System (ADS)

    Alimin; Agusu, La; Ahmad, L. O.; Kadidae, L. O.; Ramadhan, L.; Nurdin, M.; Isdayanti, N.; Asria; Aprilia M, P.; Hasrudin

    2018-05-01

    Generally, the interaction between metal ions and adsorbent is governed by many factors including; concentration of metal ions, interaction time and solution pH. In this work, we applied liquid phase adsorption for studying the interaction between Fe3+ ions and Carbon Nanofibers (CNFs) irradiated by ultrasonic waves. Kinetics and isotherms model of the Fe3+ ion adsorption was investigated by varying contact time and pH. We found that the Fe3+ ions were efficiently adsorbed on CNFs for 0.5 h in acidic pH of around 5. In order to obtain the best-fitted isotherms model, Langmuir and Freundlich’s isotherms were used in this work. The adsorption equilibrium Fe3+ metal ions on CNFs tend to follow Langmuir. Adsorption kinetics of Fe3+ ions on CNFs were investigated by using both pseudo-first and pseudo-second orders. The adsorption kinetics coincided well with the pseudo-second-order.

  1. [Characteristics of Adsorption Leaching and Influencing Factors of Dimethyl Phthalate in Purple Soil].

    PubMed

    Wang, Qiang; Song, Jiao-yan; Zeng, Wei; Wang, Fa

    2016-02-15

    The typical soil-purple soil in Three Gorges Reservoir was the tested soil, the characteristics of adsorption leaching of dimethyl phthalate (DMP) in contaminated water by the soil, and the influencing factors in the process were conducted using soil column leaching experiment. The results showed that the parabolic equation was the best equation describing adsorption kinetics of DMP by soils. The concentration of DMP in the leaching solution had significant effect on the adsorption amounts of DMP. With the increasing concentration of DMP in the leaching solution, the adsorption capacities of DMP by purple soil increased linearly. The ionic strength and pH in leaching solution had significant effects on adsorption of DMP. On the whole, increasing of the ionic strength restrained the adsorption. The adsorption amounts at pH 5.0-7.0 were more than those under other pH condition. The addition of exogenous organic matter (OM) in purple soil increased the adsorption amount of DMP by purple soil. However, the adsorption amount was less than those with other addition amounts of exogenous OM when the addition of exogenous OM was too high (> or = 30 g x kg(-1)). The addition of surfactant sodium dodecylbenzene sulfonic acid (SDBS) in purple soil increased the adsorption amount of DMP by purple soil. The adsorption amount was maximal when the addition amount of SDBS was 50 mg x kg(-1). However, the adsorption amounts decreased with increasing addition amounts of SDBS although the adsorption amounts were still more than that of the control group, and the adsorption amount was almost equal to that of the control group when the addition amount of SDBS was 800 mg x kg(-1). Continuous leaching time affected the vertical distribution of DMP in the soil column. When the leaching time was shorter, the upper soil column adsorbed more DMP, while the DMP concentrations in upper and lower soil columns became similar with the extension of leaching time.

  2. Ionic Adsorption and Desorption of CNT Nanoropes

    PubMed Central

    Shang, Jun-Jun; Yang, Qing-Sheng; Yan, Xiao-Hui; He, Xiao-Qiao; Liew, Kim-Meow

    2016-01-01

    A nanorope is comprised of several carbon nanotubes (CNTs) with different chiralities. A molecular dynamic model is built to investigate the ionic adsorption and desorption of the CNT nanoropes. The charge distribution on the nanorope is obtained by using a modified gradient method based on classical electrostatic theory. The electrostatic interactions among charged carbon atoms are calculated by using the Coulomb law. It was found here that the charged nanorope can adsorb heavy metal ions, and the adsorption and desorption can be realized by controlling the strength of applied electric field. The distance between the ions and the nanorope as well as the amount of ions have an effect on the adsorption capacity of the nanorope. The desorption process takes less time than that of adsorption. The study indicates that the CNT nanorope can be used as a core element of devices for sewage treatment. PMID:28335306

  3. Ionic Adsorption and Desorption of CNT Nanoropes.

    PubMed

    Shang, Jun-Jun; Yang, Qing-Sheng; Yan, Xiao-Hui; He, Xiao-Qiao; Liew, Kim-Meow

    2016-09-28

    A nanorope is comprised of several carbon nanotubes (CNTs) with different chiralities. A molecular dynamic model is built to investigate the ionic adsorption and desorption of the CNT nanoropes. The charge distribution on the nanorope is obtained by using a modified gradient method based on classical electrostatic theory. The electrostatic interactions among charged carbon atoms are calculated by using the Coulomb law. It was found here that the charged nanorope can adsorb heavy metal ions, and the adsorption and desorption can be realized by controlling the strength of applied electric field. The distance between the ions and the nanorope as well as the amount of ions have an effect on the adsorption capacity of the nanorope. The desorption process takes less time than that of adsorption. The study indicates that the CNT nanorope can be used as a core element of devices for sewage treatment.

  4. Laser-ignited frontal polymerization of shape-controllable poly(VI-co-AM) hydrogels based on 3D templates toward adsorption of heavy metal ions

    NASA Astrophysics Data System (ADS)

    Fan, Suzhen; Liu, Sisi; Wang, Xiao-Qiao; Wang, Cai-Feng; Chen, Su

    2016-06-01

    Given the increasing heavy metal pollution issue, fast preparation of polymeric hydrogels with excellent adsorption property toward heavy metal ions is very attractive. In this work, a series of poly( N-vinylimidazole-co-acrylamide) (poly(VI-co-AM)) hydrogels were synthesized via laser-ignited frontal polymerization (LIFP) for the first time. The dependence of frontal velocity and temperature on two factors monomer ratios and initiator concentrations was systematically investigated. Poly(VI-co-AM) hydrogels with any self-supporting shapes can be synthesized by a one-step LIFP in seconds through the application of 3D templates. These shape-persistent hydrogels are pH-responsive and exhibit excellent adsorption/desorption characteristics toward Mn(II), Zn(II), Cd(II), Ni(II), Cu(II) and Co(II) ions, and the adsorption conformed to the pseudo-second-order kinetic model. The reusability of the hydrogels toward mental ions adsorption was further researched, which suggested that the hydrogels can be reused without serious decrease in adsorption capacity. This work might open a promising strategy to facilely prepare shape-controllable hydrogels and expand the application of LIFP.

  5. Modeling adsorption with lattice Boltzmann equation

    PubMed Central

    Guo, Long; Xiao, Lizhi; Shan, Xiaowen; Zhang, Xiaoling

    2016-01-01

    The research of adsorption theory has recently gained renewed attention due to its critical relevance to a number of trending industrial applications, hydrogen storage and shale gas exploration for instance. The existing theoretical foundation, laid mostly in the early twentieth century, was largely based on simple heuristic molecular interaction models and static interaction potential which, although being insightful in illuminating the fundamental mechanisms, are insufficient for computations with realistic adsorbent structure and adsorbate hydrodynamics, both critical for real-life applications. Here we present and validate a novel lattice Boltzmann model incorporating both adsorbate-adsorbate and adsorbate-adsorbent interactions with hydrodynamics which, for the first time, allows adsorption to be computed with real-life details. Connection with the classic Ono-Kondo lattice theory is established and various adsorption isotherms, both within and beyond the IUPAC classification are observed as a pseudo-potential is varied. This new approach not only enables an important physical to be simulated for real-life applications, but also provides an enabling theoretical framework within which the fundamentals of adsorption can be studied. PMID:27256325

  6. Water adsorption constrained Frenkel-Halsey-Hill adsorption activation theory: Montmorillonite and illite

    NASA Astrophysics Data System (ADS)

    Hatch, Courtney D.; Greenaway, Ann L.; Christie, Matthew J.; Baltrusaitis, Jonas

    2014-04-01

    Fresh mineral aerosol has recently been found to be effective cloud condensation nuclei (CCN) and contribute to the number of cloud droplets in the atmosphere due to the effect of water adsorption on CCN activation. The work described here uses experimental water adsorption measurements on Na-montmorillonite and illite clay to determine empirical adsorption parameters that can be used in a recently derived theoretical framework (Frenkel-Halsey-Hill Activation Theory, FHH-AT) that accounts for the effect of water adsorption on CCN activation. Upon fitting the Frenkel-Halsey-Hill (FHH) adsorption model to water adsorption measurements, we find FHH adsorption parameters, AFHH and BFHH, to be 98 ± 22 and 1.79 ± 0.11 for montmorillonite and 75 ± 17 and 1.77 ± 0.11 for illite, respectively. The AFHH and BFHH values obtained from water adsorption measurements differ from values reported previously determined by applying FHH-AT to CCN activation measurements. Differences in FHH adsorption parameters were attributed to different methods used to obtain them and the hydratable nature of the clays. FHH adsorption parameters determined from water adsorption measurements were then used to calculate the critical super-saturation (sc) for CCN activation using FHH-AT. The relationship between sc and the dry particle diameter (Ddry) gave CCN activation curve exponents (xFHH) of -0.61 and -0.64 for montmorillonite and illite, respectively. The xFHH values were slightly lower than reported previously for mineral aerosol. The lower exponent suggests that the CCN activity of hydratable clays is less sensitive to changes in Ddry and the hygroscopicity parameter exhibits a broader variability with Ddry compared to more soluble aerosols. Despite the differences in AFHH, BFHH and xFHH, the FHH-AT derived CCN activities of montmorillonite and illite are quite similar to each other and in excellent agreement with experimental CCN measurements resulting from wet-generated clay aerosol

  7. Separation of acid blue 25 from aqueous solution using water lettuce and agro-wastes by batch adsorption studies

    NASA Astrophysics Data System (ADS)

    Kooh, Muhammad Raziq Rahimi; Dahri, Muhammad Khairud; Lim, Linda B. L.; Lim, Lee Hoon; Chan, Chin Mei

    2018-05-01

    Three plant-based materials, namely water lettuce (WL), tarap peel (TP) and cempedak peel (CP), were used to investigate their potentials as adsorbents using acid blue 25 (AB25) dye as a model for acidic dye. The adsorbents were characterised using Fourier transform infrared spectroscopy, X-ray fluorescence and scanning electron microscope. Batch experiments involving parameters such as pH, temperature, contact time, and initial dye concentration were done to investigate the optimal conditions for the adsorption of AB25 onto the adsorbents. Thermodynamics study showed that the uptake of AB25 by the three adsorbents was feasible and endothermic in nature. Both the Langmuir and Freundlich isotherm models can be used to describe the adsorption process of AB25 onto WL and CP while pseudo-second-order fitted the kinetics data, suggesting that chemisorptions were majorly involved. The use of 0.1 M of NaOH showed the best results in regenerating of the WL, TP and CP's adsorption ability after AB25 treatment.

  8. On the adsorption properties of magnetic fluids: Impact of bulk structure

    NASA Astrophysics Data System (ADS)

    Kubovcikova, Martina; Gapon, Igor V.; Zavisova, Vlasta; Koneracka, Martina; Petrenko, Viktor I.; Soltwedel, Olaf; Almasy, László; Avdeev, Mikhail V.; Kopcansky, Peter

    2017-04-01

    Adsorption of nanoparticles from magnetic fluids (MFs) on solid surface (crystalline silicon) was studied by neutron reflectometry (NR) and related to the bulk structural organization of MFs concluded from small-angle neutron scattering (SANS). The initial aqueous MF with nanomagnetite (co-precipitation reaction) stabilized by sodium oleate and MF modified by a biocompatible polymer, poly(ethylene glycol) (PEG), were considered. Regarding the bulk structure it was confirmed in the SANS experiment that comparatively small and compact (size 30 nm) aggregates of nanoparticle in the initial sample transfer to large and developed (size>130 nm, fractal dimension 2.7) associates in the PEG modified MF. This reorganization in the aggregates correlates with the changes in the neutron reflectivity that showed that a single adsorption layer of individual nanoparticles on the oxidized silicon surface for the initial MF disappears after the PEG modification. It is concluded that all particles in the modified fluid are in the aggregates that are not adsorbed by silicon.

  9. Adsorption and desorption for dynamics transport of hexavalent chromium Cr(Ⅵ) in soil column

    NASA Astrophysics Data System (ADS)

    Tong, J.

    2017-12-01

    Batch experiments have been carried out to study the adsorption of heavy metals in soils, and the migration and transformation of hexavalent chromium Cr(Ⅵ) in the soil of a vegetable base were studied by dynamic adsorption and desorption soil column experiments. The aim of this study was to investigate the effect of initial concentration and pH value on the adsorption process of Cr(Ⅵ). Breakthrough curve were used to evaluate the capacity of Cr(Ⅵ) adsorption in soil columns. The results show that the higher the initial concentration, the worse the adsorption capacity of Cr(Ⅵ). The adsorption of Cr(Ⅵ) was strongly sensitive to pH value. The capacity of Cr(Ⅵ) adsorption is maximized at very low pH value. This may be due to changes in pH that cause a series of complex reactions in Cr(Ⅵ). In a strongly acidic environment, the reaction of Cr(Ⅵ) with hydrogen ions is accompanied by the formation of Cr3+, which reacts with the soil free iron-aluminum oxide to produce hydroxide in the soil. The results of the desorption experiments indicate that Cr(Ⅵ) is more likely to leach from this soil, but if the eluent is strong acid solution, the leaching process will be slow and persistent. The program CXTFIT was used to fit the breakthrough curve to estimate parameters. The results of the calculation of the dispersion coefficient (D) can be obtained by this program. The two-site model fit the breakthrough curve data of Cr(Ⅵ) well, and the parameters calculated by CXTFIT can be used to explain the behavior of Cr(Ⅵ) migration and transformation in soil columns. When pH=2, the retardation factor (R) reach at 79.71 while the value of the R is generally around 10 in other experiments. The partitioning coefficient β shows that more than half of the adsorption sites are rate-limited in this adsorption process and non-equilibrium effects the Cr(Ⅵ) transport process in this soil.

  10. Properties and reactivity of Fe-organic matter associations formed by coprecipitation versus adsorption: Clues from arsenate batch adsorption

    NASA Astrophysics Data System (ADS)

    Mikutta, Robert; Lorenz, Dennis; Guggenberger, Georg; Haumaier, Ludwig; Freund, Anja

    2014-11-01

    Ferric oxyhydroxides play an important role in controlling the bioavailability of oxyanions such as arsenate and phosphate in soil. Despite this, little is known about the properties and reactivity of Fe(III)-organic matter phases derived from adsorption (reaction of organic matter (OM) to post-synthesis Fe oxide) versus coprecipitation (formation of Fe oxides in presence of OM). Coprecipitates and adsorption complexes were synthesized at pH 4 using two natural organic matter (NOM) types extracted from forest floor layers (Oi and Oa horizon) of a Haplic Podzol. Iron(III) coprecipitates were formed at initial molar metal-to-carbon (M/C) ratios of 1.0 and 0.1 and an aluminum (Al)-to-Fe(III) ratio of 0.2. Sample properties were studied by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), N2 gas adsorption, dynamic light scattering, and electrophoretic mobility measurements. Arsenic [As(V)] adsorption to Fe-OM phases was studied in batch experiments (168 h, pH 4, 100 μM As). The organic carbon (OC) contents of the coprecipitates (82-339 mg g-1) were higher than those of adsorption complexes (31 and 36 mg g-1), leading to pronounced variations in specific surface area (9-300 m2 g-1), average pore radii (1-9 nm), and total pore volumes (11-374 mm3 g-1) but being independent of the NOM type or the presence of Al. The occlusion of Fe solids by OM (XPS surface concentrations: 60-82 atom% C) caused comparable pHPZC (1.5-2) of adsorption complexes and coprecipitates. The synthesis conditions resulted in different Fe-OM association modes: Fe oxide particles in 'M/C 0.1' coprecipitates covered to a larger extent the outermost aggregate surfaces, for some 'M/C 1.0' coprecipitates OM effectively enveloped the Fe oxides, while OM in the adsorption complexes primarily covered the outer aggregate surfaces. Despite of their larger OC contents, adsorption of As(V) was fastest to coprecipitates formed at low Fe availability (M/C 0.1) and facilitated by desorption of weakly

  11. Thermodynamics of Methane Adsorption on Copper HKUST-1 at Low Pressure.

    PubMed

    Wu, Di; Guo, Xiaofeng; Sun, Hui; Navrotsky, Alexandra

    2015-07-02

    Metal-organic frameworks (MOFs) can be engineered as natural gas storage materials by tuning the pore structures and surface properties. Here we report the direct measurement of CH4 adsorption enthalpy on a paddlewheel MOF (Cu HKUST-1) using gas adsorption calorimetry at 25 °C at low pressures (below 1 bar). In this pressure region, the CH4-CH4 intermolecular interactions are minimized and the energetics solely reflects the CH4-MOF interactions. Our results suggest moderately exothermic physisorption with an enthalpy of -21.1 ± 1.1 kJ/mol CH4 independent of coverage. This calorimetric investigation complements previous computational and crystallographic studies by providing zero coverage enthalpies of CH4 adsorption. The analysis of the new and literature data suggests that in initial stages of adsorption the CH4-HKUST-1 interaction tends to be more sensitive to the pore dimension than to the guest polarizability, suggesting a less specific chemical binding role for the open Cu site.

  12. Thermodynamics of methane adsorption on copper HKUST-1 at low pressure

    DOE PAGES

    Wu, Di; Guo, Xiaofeng; Sun, Hui; ...

    2015-06-11

    Metal–organic frameworks (MOFs) can be engineered as natural gas storage materials by tuning the pore structures and surface properties. Here we report the direct measurement of CH₄ adsorption enthalpy on a paddlewheel MOF (Cu HKUST-1) using gas adsorption calorimetry at 25 °C at low pressures (below 1 bar). In this pressure region, the CH₄–CH₄ intermolecular interactions are minimized and the energetics solely reflects the CH₄–MOF interactions. Our results suggest moderately exothermic physisorption with an enthalpy of -21.1 ± 1.1 kJ/mol CH₄ independent of coverage. The calorimetric investigation complements previous computational and crystallographic studies by providing zero coverage enthalpies of CH₄more » adsorption. The analysis of the new and literature data suggests that in initial stages of adsorption the CH₄–HKUST-1 interaction tends to be more sensitive to the pore dimension than to the guest polarizability, suggesting a less specific chemical binding role for the open Cu site.« less

  13. Optimizing adsorption of fluoride from water by modified banana peel dust using response surface modelling approach

    NASA Astrophysics Data System (ADS)

    Bhaumik, Ria; Mondal, Naba Kumar

    2016-06-01

    The present work highlighted the effective application of banana peel dust (BPD) for removal of fluoride (F-) from aqueous solution. The effects of operating parameters such as pH, initial concentration, adsorbent dose, contact time, agitation speed and temperature were analysed using response surface methodology. The significance of independent variables and their interactions were tested by the analysis of variance and t test statistics. Experimental results revealed that BPD has higher F- adsorption capacity (17.43, 26.31 and 39.5 mg/g). Fluoride adsorption kinetics followed pseudo-second-order model with high correlation of coefficient value (0.998). On the other hand, thermodynamic data suggest that adsorption is favoured at lower temperature, exothermic in nature and enthalpy driven. The adsorbents were characterised through scanning electron microscope, Fourier transform infrared spectroscopy and point of zero charges (pHZPC) ranges from pH 6.2-8.2. Finally, error analysis clearly demonstrates that all three adsorbents are well fitted with Langmuir isotherm compared to the other isotherm models. The reusable properties of the material support further development for commercial application purpose.

  14. Ultrasound-assisted preparation of a nanostructured zinc(II) amine pillar metal-organic framework as a potential sorbent for 2,4-dichlorophenol adsorption from aqueous solution.

    PubMed

    Abazari, Reza; Salehi, Ghazal; Mahjoub, Ali Reza

    2018-09-01

    Using a green and simple route with ultrasound illumination under atmospheric pressure and at room temperature, the nanosized preparation of a Zn(II) metal-organic framework, [Zn(ATA)(BPD)] ∞ (ATA = 2-aminoterephthalic acid), BPD = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene), having nano-plate shape and 3D channel framework, was considered and the product was named as compound 1. The X-ray diffraction (XRD), scanning electron microscopy (SEM), IR spectroscopy, Brunauer-Emmett-Teller (BET), and thermogravimetric analysis (TGA) were used for characterization of the synthesized micro/nano-structures. Further, impact of different sonication times and initial reagent contents on the shape and size of the micro/nano-structures was investigated. The results show that under ultrasound irradiation non-aggregated plates with uniform morphology can be obtained with content of [0.0125] M of the initial reagents in the presence of triethylamine (TEA) at 120 min. Moreover, through N 2 adsorption, effect of the preparation route on the porosity was explored. The bulk and nano-plates of compound 1 were also studied for adsorption of 2,4-dichlorophenol as a pollutant sample. Kinetic studies indicated that 2,4-dichlorophenol adsorption via MOF nano-plates are of first-order kinetics. Also, MOF nano-plates have significantly been reutilized for five times while their adsorption properties have remained unchanged. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Adsorption of bovine serum albumin and urease by biochar

    NASA Astrophysics Data System (ADS)

    Wang, Wenjing; Chen, Lei; Zhang, Yipeng; Liu, Guocheng

    2017-04-01

    The application of biochar to soil improvement inevitably affects free soil enzymes. However, there is little information on the interaction of soil enzymes with biochar to our knowledge. We thus investigated the adsorption of bovine serum albumin (BSA) and urease onto two biochars from giant reed pyrolyzed at 300 and 600 °C (BCF300 and BCF600). The adsorption amount of BSA and urease on BCF300 and BCF600 was up to 45.6-209 mg/g and 75.3-808 mg/g, respectively, suggesting that the test proteins could be adsorbed onto the biochars effectively. The sorption rate of BSA and urease significantly decreased as the protein concentration increased, suggesting that their adsorption was nonlinear. For the same initial concentration (50 or 200 mg/L), the adsorption amount of BSA on the biochars was lower, only 25.9-60.5% of that of urease. The high specific surface area and hydrophobicity of the biochars may play important roles on the immobilization of the proteins by biochars. These findings will be helpful for better understanding the effects of biochar adding on the soil enzymes.

  16. Adsorption and recognition characteristics of surface molecularly imprinted polymethacrylic acid/silica toward genistein.

    PubMed

    Zhang, Yanyan; Gao, Baojiao; An, Fuqiang; Xu, Zeqing; Zhang, Tingting

    2014-09-12

    In this paper, on the basis of surface-initiated graft polymerization, a new surface molecular imprinting technique is established by molecular design. And molecularly imprinted polymer MIP-PMAA/SiO2 is successfully prepared with genistein as template. The adsorption and recognition characteristics of MIP-PMAA/SiO2 for genistein are studied in depth by using static method, dynamic method and competitive adsorption experiment. The experimental results show that MIP-PMAA/SiO2 possesses very strong adsorption affinity and specific recognition for genistein. The saturated adsorption capacity could reach to 0.36mmolg(-1). The selectivity coefficients relative to quercetin and rutin are 5.4 and 11.8, respectively. Besides, MIP-PMAA/SiO2 is regenerated easily and exhibits excellent reusability. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Eco-friendly polyvinyl alcohol/carboxymethyl cellulose hydrogels reinforced with graphene oxide and bentonite for enhanced adsorption of methylene blue.

    PubMed

    Dai, Hongjie; Huang, Yue; Huang, Huihua

    2018-04-01

    Eco-friendly polyvinyl alcohol/carboxymethyl cellulose (isolated from pineapple peel) hydrogels reinforced with graphene oxide and bentonite were prepared as efficient adsorbents for methylene blue (MB). The structure and morphology of the prepared hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), thermogravimetry (TG) and differential scanning calorimetry (DSC). Introducing graphene oxide and bentonite into the hydrogels evidently enhanced the thermal stability, swelling ability and MB adsorption capacity. The effects of initial concentration of MB, pH, contact time and temperature on MB adsorption capacity of the prepared hydrogels were investigated. Adsorption kinetics and equilibrium adsorption isotherm fitted pseudo-second-order kinetic model and Langmuir isotherm model well, respectively. After introducing graphene oxide and bentonite into the hydrogels, the maximum adsorption capacity calculated from the Langmuir isotherm model reached 172.14 mg/g at 30 °C, obviously higher than the hydrogels prepared without these additions (83.33 mg/g). Furthermore, all the prepared hydrogels also displayed good reusability for the efficient removal of MB. Consequently, the prepared hydrogels could be served as eco-friendly, stable, efficient and reusable adsorbents for anionic dyes in wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Negligible effects of tryptophan on the aflatoxin adsorption of sodium bentonite.

    PubMed

    Magnoli, A P; Copia, P; Monge, M P; Magnoli, C E; Dalcero, A M; Chiacchiera, S M

    2014-01-01

    The main objective of this study was to determine if the competitive adsorption of tryptophan (Trp) and aflatoxin B₁ (AFB₁) could potentially affect the ability of a sodium bentonite (NaB) to prevent aflatoxicosis in monogastric animals. The adsorption of Trp and AFB₁ on this adsorbent is fast and could be operating on the same time-scale making competition feasible. In vitro competitive adsorption experiments under simulated gastrointestinal conditions were performed. A high affinity of the clay for Trp and NaB was observed. The effect of an excess of KCl to mimic the ionic strength of the physiological conditions were also investigated. A six-times decrease in the Trp surface excess at saturation was observed. A similar behaviour was previously found for AFB₁ adsorption. Taking into account the amount of Trp adsorbed by the clay and the usual adsorbent supplementation level in diets, a decrease in Trp bioavailability is not expected to occur. Tryptophan adsorption isotherms on NaB were 'S'-shaped and were adjusted by the Frumkin-Fowler-Guggenheim model. The reversibility of the adsorption processes was investigated in order to check a potential decrease in the ability of NaB to protect birds against chronic aflatoxicoses. Adsorption processes were completely reversible for Trp, while almost irreversible for AFB₁. In spite of the high affinity of the NaB for Trp, probably due to the reversible character of Trp adsorption, no changes in the AFB₁ adsorption isotherm were observed when an excess of the amino acid was added to the adsorption medium. As a consequence of the preferential and irreversible AFB₁ adsorption and the reversible weak binding of Trp to the NaB, no changes in the aflatoxin sorption ability of the clay are expected to occur in the gastrointestinal tract of birds.

  19. Selective adsorption of Pb(II), Cd(II), and Ni(II) ions from aqueous solution using chitosan-MAA nanoparticles.

    PubMed

    Heidari, Aghdas; Younesi, Habibollah; Mehraban, Zahra; Heikkinen, Harri

    2013-10-01

    Chitosan-MAA nanoparticles (CS-MAA) with an average size of 10-70 nm were prepared by polymerizing chitosan with methacrylic acid in aqueous solution. The physicochemical properties of nanoparticles were investigated using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS) and nuclear magnetic resonance (NMR). The adsorption of Pb(II), Cd(II) and Ni(II) from aqueous solution on CS-MAA was studied in a batch system. The effects of the solution pH, initial metal concentration, contact time, and dosage of the adsorbent on the adsorption process were examined. The experimental data were analyzed using the pseudo-second-order kinetic equations and the Langmuir, Freundlich and Redlish-Peterson isotherms. The maximum adsorption capacity was 11.30, 1.84, and 0.87 mg/g for Pb(II), Cd(II) and Ni(II) ions, respectively, obtained by the Langmuir isotherm. However, the adsorption isotherm was better explained by the Freundlich rather than by the Langmuir model, as the high correlation coefficients (R(2)>0.99) were obtained at a higher confidence level. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Novel hydrophobic PDVB/R-SiO2 for adsorption of volatile organic compounds from highly humid gas stream.

    PubMed

    Lu, Han-feng; Cao, Jie-jing; Zhou, Ying; Zhan, De-li; Chen, Yin-fei

    2013-11-15

    A novel organic-inorganic hydrophobic polydivinylbenzene-silica adsorbent (PDVB/R-SiO2) was successfully prepared by introducing a specific amount of divinylbenzene and solvent (i.e., tetrahydrofuran) to SiO2pores and initiating polymerization under solvothermal conditions. New smaller structures and surface areas were formed in the SiO2 pores. The PDVB/R-SiO2-0.5 samples exhibited a bimodal pore size distribution with both SiO2 micropores/mesopores (0.5-2.0 nm) and mesopores (2.0-5.0 nm). The surface areas increased from 116 m(2)/g (SiO2) to 246 m(2)/g. The breakthrough curves of toluene adsorption indicated that the amount adsorbed on PDVB/R-SiO2-0.5 was 12 times higher than that on SiO2. The highly humid environment exhibited no effect on adsorption because the surface of PDVB was functionalized. The adsorbed toluene was easily desorbed in hot N2 stream at 100 °C. After 10 adsorption-desorption cycles, PDVB/R-SiO2-0.5 continued exhibiting excellent adsorption, indicating superior structural and regeneration abilities. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Adsorption of bentazon on CAT and CARBOPAL activated carbon: Experimental and computational study

    NASA Astrophysics Data System (ADS)

    Spaltro, Agustín; Simonetti, Sandra; Torrellas, Silvia Alvarez; Rodriguez, Juan Garcia; Ruiz, Danila; Juan, Alfredo; Allegretti, Patricia

    2018-03-01

    Removal of the bentazon by adsorption on two different types of activated carbon was investigated under various experimental conditions.Kinetics of adsorption is followed and the adsorption isotherms of the pesticide are determined. The effects of the changes in pH, ionic strength and temperature are analyzed. Computational simulation was employed to analyze the geometry and the energy of pesticide absorption on activated carbon. Concentration of bentazon decreases while increase all the variables, from the same initial concentration. Experimental data for equilibrium was analyzed by three models: Langmuir, Freundlich and Guggenheim-Anderson-de Boer isotherms. Pseudo-first and pseudo-second-order kinetics are tested with the experimental data, and pseudo-second-order kinetics was the best for the adsorption of bentazon by CAT and CARBOPAL with coefficients of correlation R2 = 0.9996 and R2 = 0.9993, respectively. The results indicated that both CAT and CARBOPAL are very effective for the adsorption of bentazon from aqueous solutions, but CAT carbon has the greater capacity.

  2. Equilibrium adsorption of caffeic, chlorogenic and rosmarinic acids on cationic cross-linked starch with quaternary ammonium groups.

    PubMed

    Simanaviciute, Deimante; Klimaviciute, Rima; Rutkaite, Ramune

    2017-02-01

    In the present study, the equilibrium adsorption of caffeic acid (CA) and its derivatives, namely, chlorogenic (CGA) and rosmarinic (RA) acids on cationic cross-linked starch (CCS) with degree of substitution of quaternary ammonium groups of 0.42 have been investigated in relation to the structure and acidity of phenolic acids. The Langmuir, Freundlich and Dubinin-Radushkevich adsorption models have been used to describe the equilibrium adsorption of CA, CGA and RA from their initial solutions and solutions having the equimolar amount of NaOH at different temperatures. In the case of adsorption from the initial solutions of acids the values of adsorption parameters were closely related to the dissociation constants of investigated acids. According to the increasing effectiveness of adsorption, phenolic acids could be arranged in the following order: CA

  3. Equilibrium isotherms, kinetics, and thermodynamics studies for congo red adsorption using calcium alginate beads impregnated with nano-goethite.

    PubMed

    Munagapati, Venkata Subbaiah; Kim, Dong-Su

    2017-07-01

    The present study is concerned with the batch adsorption of congo red (CR) from an aqueous solution using calcium alginate beads impregnated with nano-goethite (CABI nano-goethite) as an adsorbent. The optimum conditions for CR removal were determined by studying operational variables viz. pH, adsorbent dose, contact time, initial dye ion concentration and temperature. The CABI nano-goethite was characterized by Fourier transform infrared spectroscopy (FTIR), X- ray diffraction (XRD) and Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) analysis. The CR sorption data onto CABI nano-goethite were described using Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models. The results show that the best fit was achieved with the Langmuir isotherm model. The maximum adsorption capacity (181.1mg/g) of CR was occurred at pH 3.0. Kinetic studies showed that the adsorption followed a pseudo-second-order model. Desorption experiments were carried out to explore the feasibility of regenerating the adsorbent and the adsorbed CR from CABI nano-goethite. The best desorbing agent was 0.1M NaOH with an efficiency of 94% recovery. The thermodynamic parameters ΔG°, ΔH°, and ΔS° for the CR adsorption were determined by using adsorption capacities at five different temperatures (293, 303, 313, 323 and 303K). Results show that the adsorption process was endothermic and favoured at high temperature. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Application of zeolite-activated carbon macrocomposite for the adsorption of Acid Orange 7: isotherm, kinetic and thermodynamic studies.

    PubMed

    Lim, Chi Kim; Bay, Hui Han; Neoh, Chin Hong; Aris, Azmi; Abdul Majid, Zaiton; Ibrahim, Zaharah

    2013-10-01

    In this study, the adsorption behavior of azo dye Acid Orange 7 (AO7) from aqueous solution onto macrocomposite (MC) was investigated under various experimental conditions. The adsorbent, MC, which consists of a mixture of zeolite and activated carbon, was found to be effective in removing AO7. The MC were characterized by scanning electron microscopy (SEM), energy dispersive X-ray, point of zero charge, and Brunauer-Emmett-Teller surface area analysis. A series of experiments were performed via batch adsorption technique to examine the effect of the process variables, namely, contact time, initial dye concentration, and solution pH. The dye equilibrium adsorption was investigated, and the equilibrium data were fitted to Langmuir, Freundlich, and Tempkin isotherm models. The Langmuir isotherm model fits the equilibrium data better than the Freundlich isotherm model. For the kinetic study, pseudo-first-order, pseudo-second-order, and intraparticle diffusion model were used to fit the experimental data. The adsorption kinetic was found to be well described by the pseudo-second-order model. Thermodynamic analysis indicated that the adsorption process is a spontaneous and endothermic process. The SEM, Fourier transform infrared spectroscopy, ultraviolet-visible spectral and high performance liquid chromatography analysis were carried out before and after the adsorption process. For the phytotoxicity test, treated AO7 was found to be less toxic. Thus, the study indicated that MC has good potential use as an adsorbent for the removal of azo dye from aqueous solution.

  5. Novel adsorbent for DNA adsorption: Fe(3+)-attached sporopollenin particles embedded composite cryogels.

    PubMed

    Ceylan, Şeyda; Odabaşı, Mehmet

    2013-12-01

    The aim of this study is to prepare supermacroporous cryogels embedded with Fe(3+)-attached sporopollenin particles (Fe(3++)-ASPs) having large surface area for high DNA adsorption capacity. Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA)-based monolithic cryogel column embedded with Fe3+(+)-ASPs was prepared by radical cryo-copolymerization of 2-hydroxyethyl methacrylate (HEMA) with N,N´-methylene- bis-acrylamide (MBAAm) as cross-linker directly in a plastic syringe for DNA adsorption studies. Firstly, Fe3+(+) ions were attached to the sporopollenin particles (SPs), then the supermacroporous PHEMA cryogel with embedded Fe(3++)-ASPs was produced by free radical polymerization using N,N,N´, N´-Tetramethylethylenediamine (TEMED) and ammonium persulfate (APS) as initiator/activator pair in an ice bath. Optimum conditions of adsorption experiments were performed at pH 6.0 (0.02 M Tris buffer containing 0.2 M NaCl), with flow rate of 0.5 mL/min, and at 5°C. The maximum amount of DNA adsorption from aqueous solution was very high (109 mg/g SPs) with initial concentration of 3 mg/mL. It was observed that DNA could be repeatedly adsorbed and desorbed with this composite cryogel without significant loss of adsorption capacity. As a result, higher amounts of DNA adsorbed these composite cryogels are expected to be good candidate for achieving higher removal of anti-DNA antibodies from systemic lupus erythematosus (SLE) patients plasma.

  6. The adsorption of rare earth ions using carbonized polydopamine nano shells

    DOE PAGES

    Sun, Xiaoqi; Luo, Huimin; Mahurin, Shannon Mark; ...

    2016-01-07

    Herein we report the structure effects of nano carbon shells prepared by carbonized polydopamine for rare earth elements (REEs) adsorption for the first time. The solid carbon sphere, 60 nm carbon shell and 500 nm carbon shell were prepared and investigated for adsorption and desorption of REEs. The adsorption of carbon shells for REEs was found to be better than the solid carbon sphere. The effect of acidities on the adsorption and desorption properties was discussed in this study. The good adsorption performance of carbon shells can be attributed to their porous structure, large specific surface area, amine group andmore » carbonyl group of dopamine.« less

  7. Adsorption of clofibric acid and ketoprofen onto powdered activated carbon: effect of natural organic matter.

    PubMed

    Gao, Yaohuan; Deshusses, Marc A

    2011-12-01

    The adsorption of two acidic pharmaceutically active compounds (PhACs), clofibric acid and ketoprofen, onto powdered activated carbon (PAC) was investigated with a particular focus on the influence of natural organic matter (NOM) on the adsorption of the PhACs. Suwannee River humic acids (SRHAs) were used as a substitute for NOM. Batch adsorption experiments were conducted to obtain adsorption kinetics and adsorption isotherms with and without SRHAs in the system. The adsorption isotherms and adsorption kinetics showed that the adsorption ofclofibric acid was not significantly affected by the presence of SRHAs at a concentration of 5 mg (as carbon) L(-1). An adsorption capacity of 70 to 140 mg g(-1) was observed and equilibrium was reached within 48 h. In contrast, the adsorption of ketoprofen was markedly decreased (from about 120 mg g(-1) to 70-100 mg g(-1)) in the presence of SRHAs. Higher initial concentrations of clofibric acid than ketoprofen during testing may explain the different behaviours that were observed. Also, the more hydrophobic ketoprofen molecules may have less affinity for PAC when humic acids (which are hydrophilic) are present. The possible intermolecular forces that could account for the different behaviour of clofibric acid and ketoprofen adsorption onto PAC are discussed. In particular, the relevance of electrostatic forces, electron donor-acceptor interaction, hydrogen bonding and London dispersion forces are discussed

  8. Adsorption of antimony onto iron oxyhydroxides: adsorption behavior and surface structure.

    PubMed

    Guo, Xuejun; Wu, Zhijun; He, Mengchang; Meng, Xiaoguang; Jin, Xin; Qiu, Nan; Zhang, Jing

    2014-07-15

    Antimony is detected in soil and water with elevated concentration due to a variety of industrial applications and mining activities. Though antimony is classified as a pollutant of priority interest by the United States Environmental Protection Agency (USEPA) and Europe Union (EU), very little is known about its environmental behavior and adsorption mechanism. In this study, the adsorption behaviors and surface structure of antimony (III/V) on iron oxides were investigated using batch adsorption techniques, surface complexation modeling (SCM), X-ray photon spectroscopy (XPS) and extended X-ray absorption fine structure spectroscopy (EXAFS). The adsorption isotherms and edges indicated that the affinity of Sb(V) and Sb(III) toward the iron oxides depended on the Sb species, solution pH, and the characteristics of iron oxides. Sb(V) adsorption was favored at acidic pH and decreased dramatically with increasing pH, while Sb(III) adsorption was constant over a broad pH range. When pH is higher than 7, Sb(III) adsorption by goethite and hydrous ferric oxide (HFO) was greater than Sb(V). EXAFS analysis indicated that the majority of Sb(III), either adsorbed onto HFO or co-precipitated by FeCl3, was oxidized into Sb(V) probably due to the involvement of O2 in the long duration of sample preservation. Only one Sb-Fe subshell was filtered in the EXAFS spectra of antimony adsorption onto HFO, with the coordination number of 1.0-1.9 attributed to bidentate mononuclear edge-sharing ((2)E) between Sb and HFO. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Effect of Na+ impregnated activated carbon on the adsorption of NH4(+)-N from aqueous solution.

    PubMed

    Shi, Mo; Wang, Zhengfang; Zheng, Zheng

    2013-08-01

    Two kinds of activated carbons modified by Na+ impregnation after pre-treatments involving oxidation by nitric acid or acidification by hydrochloric acid (denoted as AC/N-Na and AC/HCl-Na, respectively), were used as adsorbents to remove NH4(+)-N. The surface features of samples were investigated by BET, SEM, XRD and FT-IR. The adsorption experiments were conducted in equilibrium and kinetic conditions. Influencing factors such as initial solution pH and initial concentration were investigated. A possible mechanism was proposed. Results showed that optimal NH4(+)-N removal efficiency was achieved at a neutral pH condition for the modified ACs. The Langmuir isotherm adsorption equation provided a better fit than other models for the equilibrium study. The adsorption kinetics followed both the pseudo second-order kinetics model and intra-particle kinetic model. Chemical surface analysis indicated that Na+ ions form ionic bonds with available surface functional groups created by pre-treatment, especially oxidation by nitric acid, thus increasing the removal efficiency of the modified ACs for NH4(+)-N. Na(+)-impregnated ACs had a higher removal capability in removing NH4(+)-N than unmodified AC, possibly resulting from higher numbers of surface functional groups and better intra-particle diffusion. The good fit of Langmuir isotherm adsorption to the data indicated the presence of monolayer NH4(+)-N adsorption on the active homogenous sites within the adsorbents. The applicability of pseudo second-order and intra-particle kinetic models revealed the complex nature of the adsorption mechanism. The intra-particle diffusion model revealed that the adsorption process consisted not only of surface adsorption but also intra-particle diffusion.

  10. Evaluation of blood adsorption onto dialysis membranes by time-of-flight secondary ion mass spectrometry and near-field infrared microscopy.

    PubMed

    Aoyagi, Satoka; Abe, Kiyoshi; Yamagishi, Takayuki; Iwai, Hideo; Yamaguchi, Satoru; Sunohara, Takashi

    2017-11-01

    Blood adsorption onto the inside surface of hollow fiber dialysis membranes was investigated by means of time-of-flight secondary ion mass spectrometry (TOF-SIMS) and near-field infrared microscopy (NFIR) in order to evaluate the biocompatibility and permeability of dialysis membranes. TOF-SIMS is useful for the imaging of particular molecules with a high spatial resolution of approximately 100 nm. In contrast, infrared spectra provide quantitative information and NFIR enables analysis with a high spatial resolution of less than 1 μm, which is close to the resolution of TOF-SIMS. A comparison was made of one of the most widely used dialysis membranes made of polysulfone (PSf), that has an asymmetric and inhomogeneous pore structure, and a newly developed asymmetric cellulose triacetate (ATA) membrane that also has an asymmetric pore structure, even though the conventional cellulose triacetate membrane has a symmetric and homogeneous pore structure. As a result, it was demonstrated that blood adsorption on the inside surface of the ATA membrane is more reduced than that on the PSf membrane. Graphical abstract Analysis of blood adsorption on inside surface of hollow fiber membrane.

  11. Comparative studies on adsorptive removal of heavy metal ions by biosorbent, bio-char and activated carbon obtained from low cost agro-residue.

    PubMed

    Kırbıyık, Çisem; Pütün, Ayşe Eren; Pütün, Ersan

    2016-01-01

    In this study, Fe(III) and Cr(III) metal ion adsorption processes were carried out with three adsorbents in batch experiments and their adsorption performance was compared. These adsorbents were sesame stalk without pretreatment, bio-char derived from thermal decomposition of biomass, and activated carbon which was obtained from chemical activation of biomass. Scanning electron microscopy and Fourier transform-infrared techniques were used for characterization of adsorbents. The optimum conditions for the adsorption process were obtained by observing the influences of solution pH, adsorbent dosage, initial solution concentration, contact time and temperature. The optimum adsorption efficiencies were determined at pH 2.8 and pH 4.0 for Fe(III) and Cr(III) metal ion solutions, respectively. The experimental data were modelled by different isotherm models and the equilibriums were well described by the Langmuir adsorption isotherm model. The pseudo-first-order, pseudo-second-order kinetic, intra-particle diffusion and Elovich models were applied to analyze the kinetic data and to evaluate rate constants. The pseudo-second-order kinetic model gave a better fit than the others. The thermodynamic parameters, such as Gibbs free energy change ΔG°, standard enthalpy change ΔH° and standard entropy change ΔS° were evaluated. The thermodynamic study showed the adsorption was a spontaneous endothermic process.

  12. Treatment of mining waste leachate by the adsorption process using spent coffee grounds.

    PubMed

    Ayala, Julia; Fernández, Begoña

    2018-02-15

    The removal of heavy metals from mining waste leachate by spent coffee grounds has been investigated. In synthetic solutions, metal uptake was studied in batch adsorption experiments as a function of pH, contact time, initial metal concentration, adsorbent concentration, particle size, and the effect of co-ions (Na, K, Ca, Mg, Cu, Cd, Ni, Zn). Results showed that adsorption was significantly affected by pH, showing the highest affinity within a pH range of 5-7. Sorption of heavy metals reached equilibrium in 3 h. Removal percentages of metals ions increased with increasing dosage. Particle size did not have a significant influence on metal uptake. The adsorption of heavy metals was found to fit Langmuir and Freundlich isotherms. Maximum Zn, Cd and Ni uptake values were calculated as 10.22, 5.96 and 7.51 mg/g, respectively, using unwashed coffee grounds (UCG) as the adsorbent and 5.36, 4.28 and 4.37 mg/g when employing washed coffee grounds as the adsorbent. The presence of co-ions inhibited the uptake of heavy metals, divalent ions having a more negative effect than monovalent ions. The results obtained in the experiments with mining waste leachate showed that UCG is effective in removing heavy metals.

  13. Wastewater remediation by TiO2-impregnated chitosan nano-grafts exhibited dual functionality: High adsorptivity and solar-assisted self-cleaning.

    PubMed

    Essawy, Amr A; Sayyah, S M; El-Nggar, A M

    2017-08-01

    This work provides a very infrequent and unique avenue of a novel bio-based nanografted polymeric composites achieving encouraging results in green management of dye contaminants in wastewater. A chitosan-grafted-polyN-Methylaniline (Ch-g-PNMANI) and chitosan-grafted-polyN-Methylaniline imprinted TiO 2 nanocomposites (Ch-g-PNMANI/TiO 2 ) were prepared and efficiently applied in wastewater remediation. The nanocomposites were characterized by FT-IR spectroscopy, X-ray diffraction, transmission electron microscopy, UV-Vis diffuse reflectance spectroscopy and Brunauer-Emmett-Teller surface area (BET) measurements. The prepared composites exhibit higher adsorptivity in removing remazol red RB-133 (RR RB-133) dye compared to other adsorbents reported in literature. The effects of TiO 2 loadings, initial dye concentration, contact time, and pH on dye adsorption were investigated. The maximum adsorption of dye was found at low pH values. Furthermore, Ch-g-PNMANI/TiO 2 of the optimum TiO 2 loading has higher adsorption capacity (116.3mg/g) than the pristine Ch-g-PNMANI (108.7mg/g). Moreover, the prepared adsorbents are photoactive under sunlight-irradiation. The study addresses a nanocomposite of considerable adsorption and in the same time has the fastest self-cleaning photoactivity (t 1/2 =31.5min.) under sunlight irradiation where a plausible photodegradation mechanism was proposed. Interestingly, the presented photoactive adsorbents are still effective in removing dye after five adsorption/sunlight-assisted self-cleaning photoregeneration cycles and therefore, they can be potentially applied to the rapid, "green" and low-cost remediation of RR RB-133 enriched industrial printing and dyeing wastewater. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Zinc adsorption effects on arsenite oxidation kinetics at the birnessite-water interface

    USGS Publications Warehouse

    Power, L.E.; Arai, Y.; Sparks, D.L.

    2005-01-01

    Arsenite is more toxic and mobile than As(V) in soil and sediment environments, and thus it is advantageous to explore factors that enhance oxidation of As(III) to As(V). Previous studies showed that manganese oxides, such as birnessite (??-MnO2), directly oxidized As(III). However, these studies did not explore the role that cation adsorption has on As(III) oxidation. Accordingly, the effects of adsorbed and nonadsorbed Zn on arsenite (As(III)) oxidation kinetics at the birnessite-water interface were investigated using batch adsorption experiments (0.1 g L-1; pH 4.5 and 6.0; I = 0.01 M NaCl). Divalent Zn adsorption on synthetic ??-MnO 2 in the absence of As(III) increased with increasing pH and caused positive shifts in electrophoretic mobility values at pH 4-6, indirectly suggesting inner-sphere Zn adsorption mechanisms. Arsenite was readily oxidized on birnessite in the absence of Zn. The initial As(III) oxidation rate constant decreased with increasing pH from 4.5 to 6.0 and initial As(III) concentrations from 100 to 300 ??M. Similar pH and initial As(III) concentration effects were observed in systems when Zn was present (i.e., presorbed Zn prior to As(III) addition and simultaneously added Zn-As(III) systems), but As(III) oxidation reactions were suppressed compared to the respective control systems. The suppression was more pronounced when Zn was presorbed on the ??-MnO 2 surfaces as opposed to added simultaneously with As(III). This study provides further understanding of As(III) oxidation reactions on manganese oxide surfaces under environmentally applicable conditions where metals compete for reactive sites.

  15. Nickel adsorption by magnetic alginate microcapsules containing an extractant.

    PubMed

    Ngomsik, Audrey-Flore; Bee, Agnès; Siaugue, Jean-Michel; Cabuil, Valérie; Cote, Gérard

    2006-05-01

    The adsorption of heavy metals on biomaterials was investigated by studying the potential of alginate microcapsules containing an extractant (Cyanex 272) and magnetic nanoparticles (gamma-Fe2O3) for the adsorption of nickel (II) from aqueous solutions. A two-stage kinetics behaviour was observed with 70% of the maximum sorption capacity achieved within 8 h. An increase in nickel removal with increase in pH occurred, the maximum uptake capacity being around 0.42 mmol g-1 at pH 8. The adsorption isotherm (pH about 5.3) was obtained in a wide range of initial nickel concentrations; the experimental data were fitted by a Langmuir model and the qmax value was estimated to be 0.52 mmol g-1. Moreover, including magnetic particles in the microcapsules allowed easy isolation of the beads from the aqueous solutions after the sorption process. Magnetic microcapsules are then suitable for the development of efficient biosorbents for removal and recovery of heavy metals from wastewater using magnetic separation.

  16. Adsorption of Methyl Tertiary Butyl Ether on Granular Zeolites: Batch and Column Studies

    PubMed Central

    Abu-Lail, Laila; Bergendahl, John A.; Thompson, Robert W.

    2010-01-01

    Methyl tertiary butyl ether (MTBE) has been shown to be readily removed from water with powdered zeolites, but the passage of water through fixed beds of very small powdered zeolites produces high friction losses not encountered in flow through larger sized granular materials. In this study, equilibrium and kinetic adsorption of MTBE onto granular zeolites, a coconut shell granular activated carbon (CS-1240), and a commercial carbon adsorbent (CCA) sample was evaluated. In addition, the effect of natural organic matter (NOM) on MTBE adsorption was evaluated. Batch adsorption experiments determined that ZSM-5 was the most effective granular zeolite for MTBE adsorption. Further equilibrium and kinetic experiments verified that granular ZSM-5 is superior to CS-1240 and CCA in removing MTBE from water. No competitive-adsorption effects between NOM and MTBE were observed for adsorption to granular ZSM-5 or CS-1240, however there was competition between NOM and MTBE for adsorption onto the CCA granules. Fixed-bed adsorption experiments for longer run times were performed using granular ZSM-5. The bed depth service time model (BDST) was used to analyze the breakthrough data. PMID:20153106

  17. Equilibrium, kinetics and mechanism of Au3+, Pd2+ and Ag+ ions adsorption from aqueous solutions by graphene oxide functionalized persimmon tannin.

    PubMed

    Wang, Zhongmin; Li, Xiaojuan; Liang, Haijun; Ning, Jingliang; Zhou, Zhide; Li, Guiyin

    2017-10-01

    In this study, a novel bio-adsorbent (PT-GO) was prepared by functionalization persimmon tannin (PT) with graphene oxide (GO) and the effective adsorption behaviors of Au 3+ , Pd 2+ and Ag + ions from aqueous solution was investigated. The PT-GO was characterized by Fourier transform infrared spectrometer (FTIR), scanning electronic microscope (SEM), thermogravimetric analysis (TGA) and Zeta potential. Many influence factors such as pH value, bio-adsorbent dosage, initial concentration of metal ions and contact time were optimized. The maximum adsorption capacity for Au 3+ , Pd 2+ and Ag + was 1325.09mg/g, 797.66mg/g and 421.01mg/g, respectively. The equilibrium isotherm for the adsorption of Au 3+ and Ag + on PT-GO were found to obey the Langmuir model, while the Freundlich model fitted better for Pd 2+ . The adsorption process of Au 3+ , Pd 2+ presented relatively fast adsorption kinetics with pseudo-second-order equation as the best fitting model, while the pseudo-first-order kinetic model was suitable for describing the adsorption of Ag + . Combination of ion exchange, electrostatic interaction and physical adsorption was the mechanism for adsorption of Au 3+ , Pd 2+ and Ag + onto PT-GO bio-adsorbent. Therefore, the PT-GO bio-adsorbent would be an ideal adsorbent for removal of precious metal ions and broaden the potential applications of persimmon tannin in environmental research. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Adsorption of Water on Simulated Moon Dust Samples

    NASA Technical Reports Server (NTRS)

    Goering, John P.; Sah, Shweta; Burghaus, Uwe; Street, Kenneth W., Jr.

    2008-01-01

    A lunar regolith simulant dust sample (JSC-1a) supported on a silica wafer (SiO2/Si(111)) has been characterized by scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), and Auger electron spectroscopy (AES). The adsorption kinetics of water has been studied primarily by thermal desorption spectroscopy (TDS) and also by collecting isothermal adsorption transients. The support has been characterized by water TDS. JSC-1a consists mostly of aluminosilicate glass and other minerals containing Fe, Na, Ca, and Mg. The particle sizes span the range from a few microns up to 100 microns. At small exposures, H2O TDS is characterized by broad (100 to 450 K) structures; at large exposures distinct TDS peaks emerge that are assigned to amorphous solid water (145 K) and crystalline ice (165 K). Water dissociates on JSC-1a at small exposures but not on the bare silica support. It appears that rather porous condensed ice layers form at large exposures. At thermal impact energies, the initial adsorption probability amounts to 0.92+/-0.05.

  19. Equilibrium and kinetic adsorption study of a cationic dye by a natural adsorbent--silkworm pupa.

    PubMed

    Noroozi, B; Sorial, G A; Bahrami, H; Arami, M

    2007-01-02

    In this work the use of silkworm pupa, which is the waste of silk spinning industries has been investigated as an adsorbent for the removal of C.I. Basic Blue 41. The amino acid nature of the pupa provided a reasonable capability for dye removal. Equilibrium adsorption isotherms and kinetics were investigated. The adsorption equilibrium data were analyzed by using various adsorption isotherm models and the results have shown that adsorption behavior of the dye could be described reasonably well by either Langmuir or Freundlich models. The characteristic parameters for each isotherm have been determined. The monolayer adsorption capacity was determined to be 555 mg/g. Kinetic studies indicated that the adsorption follows pseudo-second-order kinetics with a rate constant of 0.0434 and 0.0572 g/min mg for initial dye concentration of 200 mg/l at 20 and 40 degrees C, respectively. Kinetic studies showed that film diffusion and intra-particle diffusion were simultaneously operating during the adsorption process. The rate constant for intra-particle diffusion was estimated to be 1.985 mg/g min(0.5).

  20. Impact of a commercial glyphosate formulation on adsorption of Cd(II) and Pb(II) ions on paddy soil.

    PubMed

    Divisekara, T; Navaratne, A N; Abeysekara, A S K

    2018-05-01

    Use of glyphosate as a weedicide on rice cultivation has been a controversial issue in Sri Lanka, due to the hypothesis that the metal complexes of commercial glyphosate is one of the causative factors of Chronic Kidney Disease of unknown aetiology (CKDu) prevalent in some parts of Sri Lanka. The effect of commercial glyphosate on the adsorption and desorption of Cd(II) and Pb(II) ions on selective paddy soil studied using batch experiments, over a wide concentration range, indicates that the Langmuir adsorption isotherm model is obeyed at low initial metal ion concentrations while the Freundlich adsorption isotherm model obeys at high metal ion concentrations in the presence and absence of glyphosate. For all cases, adsorption of both Cd(II) and Pb(II) ions obeys pseudo second order kinetics, suggesting that initial adsorption is a chemisorption process. In the presence of glyphosate formulation, the extent of adsorption of Cd(II) and Pb(II) ions on soil is decreased, while their desorption is increased at high concentrations of glyphosate. Low concentrations of glyphosate formulation do not significantly affect the desorption of metal ions from soil. Reduction of adsorption leads to enhance the concentration of Cd(II) and Pb(II) ions in the aqueous phase when in contact with soil. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Recovery of oil from oil-in-water emulsion using biopolymers by adsorptive method.

    PubMed

    Elanchezhiyan, S Sd; Sivasurian, N; Meenakshi, Sankaran

    2014-09-01

    In the present study, it is aimed to identify, a low cost sorbent for the recovery of oil from oil-in-water emulsion using biopolymers such as chitin and chitosan. Chitin has the greater adsorption capacity than chitosan due to its hydrophobic nature. The characterizations of chitin and chitosan were done using FTIR, SEM, EDAX, XRD, TGA and DSC techniques. Under batch equilibrium mode, a systematic study was performed to optimize the various equilibrium parameters viz., contact time, pH, dosage, initial concentration of oil, and temperature. The adsorption process reached equilibrium at 40 min of contact time and the percentage removal of oil was found to be higher (90%) in the acidic medium. The Freundlich and Langmuir models were applied to describe the equilibrium isotherms and the isotherm constants were calculated. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated to find out the nature of the sorption mechanism. The kinetic studies were investigated with reaction-based and diffusion-based models. The suitable mechanism for the removal of oil has been established. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Adsorption of lead onto smectite from aqueous solution.

    PubMed

    Mhamdi, M; Galai, H; Mnasri, N; Elaloui, E; Trabelsi-Ayadi, M

    2013-03-01

    The purpose of this research is to study the effect of a new method of adsorption using membrane filtration to determine the maximum amount of lead adsorbed by clay and investigate the behavior of the clay after adsorption of the said metal. Treatment of wastewater contaminated with heavy metals depends on the characteristics of the effluent, the amount of final discharge, the cost of treatment, and the compatibility of the treatment process. The process of adsorption of heavy metals by clays may be a simple, selective, and economically viable alternative to the conventional physical-chemical treatment. This is justified by the importance of the surface developed by this material, the presence of negative charges on the said surface, the possibility of ion exchange taking place, and its wide availability in nature. The removal of lead from wastewater was studied by using the adsorption technique and using clay as the adsorbent. A method was optimized for adsorption through a membrane approaching natural adsorption. This new method is simple, selective, and the lead adsorption time is about 3 days. The various properties of clay were determined. It was observed that the cation exchange capacity of the clay was 56 meq/100 g of hydrated clay for the raw sample and 82 meq/100 g for the purified sample. The total surface area determined by the methylene blue method was equal to 556 and 783 m(2)/g for the raw and purified samples, respectively. The adsorption kinetics depends on several parameters. The Pb(II) clay, obeys the Langmuir, Freundlich, and the Elovich adsorption isotherms with high regression coefficients. The use of this adsorbent notably decreases the cost of treatment. It was concluded that clay shows a strong adsorption capacity on Pb(II), the maximum interaction occurring with purified clay treated at high concentration of lead. It is proposed that this adsorption through a membrane be extended for the treatment of effluents containing other metals.

  3. Adsorption and removal of arsenic(V) from drinking water by aluminum-loaded Shirasu-zeolite.

    PubMed

    Xu, Yan-hua; Nakajima, Tsunenori; Ohki, Akira

    2002-06-10

    The demand for effective and inexpensive adsorbents is to increase in response to the widespread recognition of the deleterious health effects of arsenic exposure through drinking water. A novel adsorbent, aluminum-loaded Shirasu-zeolite P1 (Al-SZP1), was prepared and employed for the adsorption and removal of arsenic(V) (As(V)) ion from aqueous system. The process of adsorption follows first-order kinetics and the adsorption behavior is fitted with a Freundlich isotherm. The adsorption of As(V) is slightly dependent on the initial pH over a wide range (3-10). Al-SZP1 was found with a high As(V) adsorption ability, equivalent to that of activated alumina, and seems to be especially suitable for removal of As(V) in low concentration. The addition of arsenite, chloride, nitrate, sulfate, chromate, and acetate ions hardly affected the As(V) adsorption, whereas the coexisting phosphate greatly interfered with the adsorption. The adsorption mechanism is supposed as a ligand-exchange process between As(V) ions and the hydroxide groups present on the surface of Al-SZP1. The adsorbed As(V) ions were desorbed effectively by a 40 mM NaOH solution. Continuous operation was demonstrated in a column packed with Al-SZP1. The feasibility of this technique to practical utilization was also assessed by adsorption/desorption multiple cycles with in situ desorption/regeneration operation.

  4. Mechanisms and chemistry of dye adsorption on manganese oxides-modified diatomite.

    PubMed

    Al-Ghouti, Mohammad A; Al-Degs, Yehya S; Khraisheh, Majeda A M; Ahmad, Mohammad N; Allen, Stephen J

    2009-08-01

    The investigations into structural changes which occur during adsorbent modification and the adsorption mechanisms are essential for an effective design of adsorption systems. Manganese oxides were impregnated onto diatomite to form the type known as delta-birnessite. Initial investigations established the effectiveness of manganese oxides-modified diatomite (MOMD) to remove basic and reactive dyes from aqueous solution. The adsorption capacity of MOMD for methylene blue (MB), hydrolysed reactive black (RB) and hydrolysed reactive yellow (RY) was 320, 419, and 204mg/g, respectively. Various analytical techniques were used to characterise the structure and the mechanisms of the dye adsorption process onto MOMD such as Fourier transform infrared (FTIR), X-ray diffraction (XRD) and atomic absorption spectrometry (A.A.). A small shift to higher values of the d-spacing of dye/MOMD was observed indicating that a small amount of the dye molecules were intercalated in the MOMD structure and other molecules were adsorbed on the external surface of MOMD. Two mechanisms of dye adsorption onto MOMD were proposed; intercalation of the dye in the octahedral layers and adsorption of the dye on the MOMD external surface. Moreover, the results demonstrated that the MOMD structure was changed upon insertion of MB and RY with an obvious decrease in the intensity of the second main peak of the MOMD X-ray pattern.

  5. The adsorption of copper in a packed-bed of chitosan beads: modeling, multiple adsorption and regeneration.

    PubMed

    Osifo, Peter O; Neomagus, Hein W J P; Everson, Raymond C; Webster, Athena; vd Gun, Marius A

    2009-08-15

    In this study, exoskeletons of Cape rock lobsters were used as raw material in the preparation of chitin that was successively deacetylated to chitosan flakes. The chitosan flakes were modified into chitosan beads and the beads were cross-linked with glutaraldehyde in order to study copper adsorption and regeneration in a packed-bed column. Five consecutive adsorption and desorption cycles were carried out and a chitosan mass loss of 25% was observed, after the last cycle. Despite the loss of chitosan material, an improved efficiency in the second and third cycles was observed with the adsorbent utilizing 97 and 74% of its adsorbent capacity in the second and third cycles, respectively. The fourth and fifth cycles, however, showed a decreased efficiency, and breakage of the beads was observed after the fifth cycle. In the desorption experiments, 91-99% of the adsorbed copper was regenerated in the first three cycles. It was also observed that the copper can be regenerated at a concentration of about a thousand fold the initial concentration. The first cycle of adsorption could be accurately described with a shrinking core particle model combined with a plug flow column model. The input parameters for this model were determined by batch characterization methods, with as only fitting parameter, the effective diffusion coefficient of copper in the bead.

  6. Adsorptive potential of cationic Basic Yellow 2 (BY2) dye onto natural untreated clay (NUC) from aqueous phase: Mass transfer analysis, kinetic and equilibrium profile

    NASA Astrophysics Data System (ADS)

    Öztürk, A.; Malkoc, E.

    2014-04-01

    In this work, natural untreated clay (NUC) was studied for the removal of Basic Yellow 2 (BY2) from aqueous solution in batch system. The effects of initial BY2 concentration, contact time, solution temperature and solution pH on BY2 adsorption were investigated. Nitrogen sorption measurements were employed to investigate the variation in surface and pore properties after dye adsorption. The adsorbent was characterized by means of FTIR, PSD, TEM, XRD and BET analysis. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Temkin and Scatchard isotherm models. The maximum monolayer adsorption capacity was found to be 833.33 mg/g at 25 °C (at room temperature). The pseudo-second-order kinetic model provided the best fit to the experimental datas compared with pseudo-first-order kinetic adsorption models. To explain mass transfer mechanism of BY2 adsorption, obtained experimental datas were applied Weber and Morris model, Body and Frusawa and Smith models. The results show that the adsorption process is controlled by film diffusion. The thermodynamic parameters such as, Gibbs free energy changes (ΔG°), standard enthalpy change (ΔH°) and standard entropy change (ΔS°) were determined. Adsorption of BY2 on NUC is exothermic and spontaneous in nature. The calculated activation energy of adsorption was found to be 5.24 kJ/mol for BY2. This value indicates that the adsorption process is a physisorption.

  7. Time required to initiate outbreak and pandemic observational research.

    PubMed

    Rishu, Asgar H; Marinoff, Nicole; Julien, Lisa; Dumitrascu, Mariana; Marten, Nicole; Eggertson, Shauna; Willems, Su; Ruddell, Stacy; Lane, Dan; Light, Bruce; Stelfox, Henry T; Jouvet, Philippe; Hall, Richard; Reynolds, Steven; Daneman, Nick; Fowler, Robert A

    2017-08-01

    Observational research focused upon emerging infectious diseases such as Ebola virus, Middle East respiratory syndrome, and Zika virus has been challenging to quickly initiate. We aimed to determine the duration of start-up procedures and barriers encountered for an observational study focused upon such infectious outbreaks. At 1 pediatric and 5 adult intensive care units, we measured durations from protocol receipt to a variety of outbreak research milestones, including research ethics board (REB) approval, data sharing agreement (DSA) execution, and patient study screening initiation. The median (interquartile range) time from site receipt of the protocol to REB submission was 73 (30-126) days; to REB approval, 158 (42-188) days; to DSA completion, 276 (186-312) days; and to study screening initiation, 293 (269-391) days. The median time from REB submission to REB approval was 43 (13-85) days. The median time for all start-up procedures was 335 (188-335) days. There is a lengthy start-up period required for outbreak-focused research. Completing DSAs was the most time-consuming step. A reactive approach to newly emerging threats such as Ebola virus, Middle East respiratory syndrome, and Zika virus will likely not allow sufficient time to initiate research before most outbreaks are advanced. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  8. The adsorption of biogenic amines on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sidorenko, I. G.; Markitan, O. V.; Vlasova, N. N.; Zagorovskii, G. M.; Lobanov, V. V.

    2009-06-01

    The adsorption of phenylethylamine, tryptamine, and tyramine on carbon nanotubes from aqueous solutions (pH 7.4) was studied depending on time and sorbate concentration. The suggestion was made that their interaction with electrodes was determined by electrostatic attraction between protonated amino groups and oxygen-containing functional groups of the surface of carbon. An increase in the adsorption of biological amines was caused by the interaction of the π systems of their aromatic rings with carbon surface hexagons. The adsorption of biogenic amines on carbon nanotubes was necessary for their possible electrooxidation and analytic determination by electrochemical methods with the use of carbon electrodes.

  9. Adsorption of saturated fatty acid in urea complexation: Kinetics and equilibrium studies

    NASA Astrophysics Data System (ADS)

    Setyawardhani, Dwi Ardiana; Sulistyo, Hary; Sediawan, Wahyudi Budi; Fahrurrozi, Mohammad

    2018-02-01

    Urea complexation is fractionation process for concentrating poly-unsaturated fatty acids (PUFAs) from vegetable oil or animal fats. For process design and optimization in commercial industries, it is necessary to provide kinetics and equilibrium data. Urea inclusion compounds (UICs) as the product is a unique complex form which one molecule (guest) is enclosed within another molecule (host). In urea complexation, the guest-host bonding exists between saturated fatty acids (SFAs) and crystalline urea. This research studied the complexation is analogous to an adsorption process. The Batch adsorption process was developed to obtain the experimental data. The ethanolic urea solution was mixed with SFA in certain compositions and adsorption times. The mixture was heated until it formed homogenous and clear solution, then it cooled very slowly until the first numerous crystal appeared. Adsorption times for the kinetic data were determined since the crystal formed. The temperature was maintained constant at room temperature. Experimental sets of data were observed with adsorption kinetics and equilibrium models. High concentration of saturated fatty acid (SFA) was used to represent adsorption kinetics and equilibrium parameters. Kinetic data were examined with pseudo first-order, pseudo second-order and intra particle diffusion models. Linier, Freundlich and Langmuir isotherm were used to study the equilibrium model of this adsorption. The experimental data showed that SFA adsorption in urea crystal followed pseudo second-order model. The compatibility of the data with Langmuir isotherm showed that urea complexation was a monolayer adsorption.

  10. Equilibrium, kinetic and thermodynamic studies for adsorption of BTEX onto Ordered Mesoporous Carbon (OMC).

    PubMed

    Konggidinata, Mas Iwan; Chao, Bing; Lian, Qiyu; Subramaniam, Ramalingam; Zappi, Mark; Gang, Daniel Dianchen

    2017-08-15

    Chemical and petrochemical industries produce substantial amounts of wastewater everyday. This wastewater contains organic pollutants such as benzene, toluene, ethylbenzene and xylenes (BTEX) that are toxic to human and aquatic life. Ordered Mesoporous Carbon (OMC), the adsorbent that possesses the characteristics of an ideal adsorbent was investigated to understand its properties and suitability for BTEX removal. Adsorption isotherms, adsorption kinetics, the effects of initial BTEX concentrations and temperatures on the adsorption process were studied. The OMCs were characterized using surface area and pore size analyzer, transmission electron microscopy (TEM), elemental analysis, thermogravimetric analysis (TGA) and fourier transform infrared spectroscopy (FTIR). The results suggested that the Langmuir Isotherm and Pseudo-Second-Order Models described the experimental data well. The thermodynamic parameters, Gibbs free energy (ΔG°), the enthalpy change (ΔH°) and the entropy change (ΔS°) of adsorption indicated that the adsorption processes were physical, endothermic, and spontaneous. In addition, OMC had 27% higher overall adsorption capacities compared to granular activated carbon (GAC). Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Hg(II) adsorption using amidoximated porous acrylonitrile/itaconic copolymers prepared by suspended emulsion polymerization.

    PubMed

    Ji, Chunnuan; Qu, Rongjun; Chen, Hou; Liu, Xiguang; Sun, Changmei; Ma, Caixia

    2016-01-01

    Initially, porous acrylonitrile/itaconic acid copolymers (AN/IA) were prepared by suspended emulsion polymerization. Successively, the cyano groups in AN/IA copolymers were converted to amidoxime (AO) groups by the reaction with hydroxylamine hydrochloride. The structures of the AN/IA and amidoximated AN/IA (AO AN/IA) were characterized by infrared spectroscopy, scanning electron microscopy, and porous structural analysis. The adsorption properties of AO AN/IA for Hg(II) were investigated. The results show that AO AN/IA has mesopores and macropores, and surface area of 11.71 m(2) g(-1). It was found that AO AN/IA has higher affinity for Hg(II), with the maximum adsorption capacity of 84.25 mg g(-1). The AO AN/IA also can effectively remove Hg(II) from different binary metal ion mixture systems. Furthermore, the adsorption kinetics and thermodynamics were studied in detail. The adsorption equilibrium can quickly be achieved in 4 h determined by an adsorption kinetics study. The adsorption process is found to belong to the second-order model, and can be described by the Freundlich model.

  12. Kinetic model of water vapour adsorption by gluten-free starch

    NASA Astrophysics Data System (ADS)

    Ocieczek, Aneta; Kostek, Robert; Ruszkowska, Millena

    2015-01-01

    This study evaluated the kinetics of water vapour adsorption on the surface of starch molecules derived from wheat. The aim of the study was to determine an equation that would allow estimation of water content in tested material in any timepoint of the adsorption process aimed at settling a balance with the environment. An adsorption isotherm of water vapour on starch granules was drawn. The parameters of the Guggenheim, Anderson, and De Boer equation were determined by characterizing the tested product and adsorption process. The equation of kinetics of water vapour adsorption on the surface of starch was determined based on the Guggenheim, Anderson, and De Boer model describing the state of equilibrium and on the model of a first-order linear inert element describing the changes in water content over time.

  13. The Influence of Salt Anions on Heavy Metal Ion Adsorption on the Example of Nickel

    PubMed Central

    Mende, Mandy; Schwarz, Dana; Steinbach, Christine; Schwarz, Simona

    2018-01-01

    The biodegradable polysaccharide chitosan possesses protonated and natural amino groups at medium pH values and has therefore been used as an adsorbing material for nickel salts in water treatment. Nickel is a problematic heavy metal ion which can cause various diseases and disorders in living organisms. Here, we show the influence of oxyanions (e.g., nitrate and sulfate) to the adsorption of nickel ions. Hence, simultaneously we are addressing the increasing global problem of nitrate and sulfate ion pollution in groundwater and surface water. A series of adsorption experiments was carried out in order to determine (i) the adsorption equilibrium, (ii) the adsorption capacity in dependence on the initial nickel ion concentration, and (iii) the influence of the anion presented in solution for the adsorption capacity. Surface morphology of chitosan flakes before and after the adsorption process has been studied with SEM-EDX analysis. The chitosan flakes exhibited promising adsorption capacities of 81.9 mg·g−1 and 21.2 mg·g−1 for nickel (sulfate) and nickel (nitrate), respectively. The calculated values of Gibbs free energy change ΔG0 confirm the higher adsorption of nickel ions in presence of sulfate ions. Hence, higher anion valence leads to a higher adsorption capacity. PMID:29510485

  14. Dye and its removal from aqueous solution by adsorption: a review.

    PubMed

    Yagub, Mustafa T; Sen, Tushar Kanti; Afroze, Sharmeen; Ang, H M

    2014-07-01

    In this review article the authors presented up to-date development on the application of adsorption in the removal of dyes from aqueous solution. This review article provides extensive literature information about dyes, its classification and toxicity, various treatment methods, and dye adsorption characteristics by various adsorbents. One of the objectives of this review article is to organise the scattered available information on various aspects on a wide range of potentially effective adsorbents in the removal of dyes. Therefore, an extensive list of various adsorbents such as natural materials, waste materials from industry, agricultural by-products, and biomass based activated carbon in the removal of various dyes has been compiled here. Dye bearing waste treatment by adsorption using low cost alternative adsorbent is a demanding area as it has double benefits i.e. water treatment and waste management. Further, activated carbon from biomass has the advantage of offering an effected low cost replacement for non-renewable coal based granular activated carbon provided that they have similar or better adsorption on efficiency. The effectiveness of various adsorbents under different physico-chemical process parameters and their comparative adsorption capacity towards dye adsorption has also been presented. This review paper also includes the affective adsorption factors of dye such as solution pH, initial dye concentration, adsorbent dosage, and temperature. The applicability of various adsorption kinetic models and isotherm models for dye removal by wide range of adsorbents is also reported here. Conclusions have been drawn from the literature reviewed and few suggestions for future research are proposed. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Adsorption of calcitonin to glass.

    PubMed

    Law, S L; Shih, C L

    1999-02-01

    Surface adsorption of calcitonin on soda lime silica glass was investigated. An attempt was also made to examine the effect of additives on the inhibition of calcitonin adsorption. Results showed that the adsorption isotherms were of the Langmuir and Freundlich type, depending on pH. Less adsorption was found for calcitonin at pH 4.3. The addition of nonionic surfactants such as Pluronic F68 and Tween 80 to the calcitonin solutions demonstrated inhibition of absorption and reduction of adsorption rate. The addition of chlorobutanol also showed the effect of minimizing adsorption.

  16. Adsorption and separation of proteins by collagen fiber adsorbent.

    PubMed

    Li, Juan; Liao, Xue-pin; Zhang, Qi-xian; Shi, Bi

    2013-06-01

    The separation of proteins is a key step in biomedical and pharmaceutical industries. In the present investigation, the collagen fiber adsorbent (CFA) was exploited as column packing material to separate proteins. Bovine serum albumin (BSA), bovine hemoglobin (Hb) and lysozyme (LYS) that have different isoelectric points (pIs) were selected as model proteins to investigate the separation ability of CFA to proteins. In batch adsorption, the adsorption behaviors of these proteins on CFA under different pHs and ionic strengths indicated that the electrostatic interaction plays a predominant role in the adsorption of proteins on CFA. CFA exhibited high adsorption capacity to Hb and LYS. In column separation, the proteins were completely separated by adjusting pH and ionic strength of the eluent. The increase of flow rate could reduce the separation time with no influence on the recovery of protein in the experimental range. The protein recovery was higher than 90% even when the CFA column was re-used for 4 times in separation of BSA and LYS, and the retention time of BSA or LYS was almost constant during the repeated applications. In addition, as a practical application, LYS was successfully separated from chicken egg white powder by CFA column. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Copper (II) adsorption by the extracellular polymeric substance extracted from waste activated sludge after short-time aerobic digestion.

    PubMed

    Zhang, Zhiqiang; Zhou, Yun; Zhang, Jiao; Xia, Siqing

    2014-02-01

    The extracellular polymeric substance (EPS) extracted from waste activated sludge (WAS) after short-time aerobic digestion was investigated to be used as a novel biosorbent for Cu(2+) removal from water. The EPS consisted of protein (52.6 %, w/w), polysaccharide (30.7 %, w/w), and nucleic acid (16.7 %, w/w). Short-time aerobic digestion process of WAS for about 4 h promoted the productivity growth of the EPS for about 10 %. With a molecular weight of about 1.9 × 10(6) Da, the EPS showed a linear structure with long chains, and contained carboxyl, hydroxyl, and amino groups. The sorption kinetics was well fit for the pseudo-second-order model, and the maximum sorption capacity of the EPS (700.3 mg Cu(2+)/g EPS) was markedly greater than those of the reported biosorbents. Both Langmuir model and Freundlich model commendably described the sorption isotherm. The Gibbs free energy analysis of the adsorption showed that the sorption process was feasible and spontaneous. According to the complex results of multiple analytical techniques, including scanning electron microscopy, Fourier transform infrared spectroscopy, atomic force microscopy, etc., the adsorption process took place via both physical and chemical sorption, but the electrostatic interaction between sorption sites with the functional groups and Cu(2+) is the major mechanism.

  18. How soil organic matter composition controls hexachlorobenzene-soil-interactions: adsorption isotherms and quantum chemical modeling.

    PubMed

    Ahmed, Ashour A; Kühn, Oliver; Aziz, Saadullah G; Hilal, Rifaat H; Leinweber, Peter

    2014-04-01

    Hazardous persistent organic pollutants (POPs) interact in soil with the soil organic matter (SOM) but this interaction is insufficiently understood at the molecular level. We investigated the adsorption of hexachlorobenzene (HCB) on soil samples with systematically modified SOM. These samples included the original soil, the soil modified by adding a hot water extract (HWE) fraction (soil+3 HWE and soil+6 HWE), and the pyrolyzed soil. The SOM contents increased in the order pyrolyzed soiladsorption. The pyrolyzed soil adsorbed more HCB than the other samples at low initial concentrations, but at higher concentrations the HCB adsorption became weaker than in the samples with HWE addition. This adsorption combined with the differences in the chemical composition between the soil samples suggested that alkylated aromatic, phenol, and lignin monomer compounds contributed most to the HCB adsorption. To obtain a molecular level understanding, a test set has been developed on the basis of elemental analysis which comprises 32 representative soil constituents. The calculated binding energy for HCB with each representative system shows that HCB binds to SOM stronger than to soil minerals. For SOM, HCB binds to alkylated aromatic, phenols, lignin monomers, and hydrophobic aliphatic compounds stronger than to polar aliphatic compounds confirming the above adsorption isotherms. Moreover, quantitative structure-activity relationship (QSAR) of the binding energy with independent physical properties of the test set systems for the first time indicated that the polarizability, the partial charge on the carbon atoms, and the molar volume are the most important properties controlling HCB-SOM interactions. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. FY-2015 Methyl Iodide Deep-Bed Adsorption Test Report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Soelberg, Nicholas Ray; Watson, Tony Leroy

    2015-09-30

    Nuclear fission produces fission and activation products, including iodine-129, which could evolve into used fuel reprocessing facility off-gas systems, and could require off-gas control to limit air emissions to levels within acceptable emission limits. Deep-bed methyl iodide adsorption testing has continued in Fiscal Year 2015 according to a multi-laboratory methyl iodide adsorption test plan. Updates to the deep-bed test system have also been performed to enable the inclusion of evaporated HNO 3 and increased NO 2 concentrations in future tests. This report summarizes the result of those activities. Test results showed that iodine adsorption from gaseous methyl iodide using reducedmore » silver zeolite (AgZ) resulted in initial iodine decontamination factors (DFs, ratios of uncontrolled and controlled total iodine levels) under 1,000 for the conditions of the long-duration test performed this year (45 ppm CH3I, 1,000 ppm each NO and NO 2, very low H 2O levels [3 ppm] in balance air). The mass transfer zone depth exceeded the cumulative 5-inch depth of 4 bed segments, which is deeper than the 2-4 inch depth estimated for the mass transfer zone for adsorbing I 2 using AgZ in prior deep-bed tests. The maximum iodine adsorption capacity for the AgZ under the conditions of this test was 6.2% (6.2 g adsorbed I per 100 g sorbent). The maximum Ag utilization was 51%. Additional deep-bed testing and analyses are recommended to (a) expand the data base for methyl iodide adsorption and (b) provide more data for evaluating organic iodide reactions and reaction byproducts for different potential adsorption conditions.« less

  20. Single, binary and multi-component adsorption of some anions and heavy metals on environmentally friendly Carpobrotus edulis plant.

    PubMed

    Chiban, Mohamed; Soudani, Amina; Sinan, Fouad; Persin, Michel

    2011-02-01

    A low-cost adsorbent and environmentally friendly adsorbent from Carpobrotus edulis plant was used for the removal of NO(3)(-), H(2)PO(4)(-), Pb(2+) and Cd(2+) ions from single, binary and multi-component systems. The efficiency of the adsorbent was studied using batch adsorption technique under different experimental conditions by varying parameters such as pH, initial concentration and contact time. In single component systems, the dried C. edulis has the highest affinity for Pb(2+), followed by NO(3)(-), Cd(2+) and H(2)PO(4)(-), with adsorption capacities of 175mg/g, 125mg/g, 28mg/g and 26mg/g, respectively. These results showed that the adsorption of NO(3)(-) and H(2)PO(4)(-) ions from single and binary component systems can be successfully described by Langmuir and Freundlich isotherms. Freundlich adsorption model, showed the best fit to the single and binary experimental adsorption data. These results also indicated that the adsorption yield of Pb(2+) ion was reduced by the presence of Cd(2+) ion in binary metal mixture. The competitive adsorption of NO(3)(-), H(2)PO(4)(-), Pb(2+) and Cd(2+) ions on dried C. edulis plant shows that NO(3)(-) and H(2)PO(4)(-) anions are able to adsorb on different free binding sites and Pb(2+) and Cd(2+) cations are able to adsorb on the same active sites of C. edulis particles. The dried C. edulis was found to be efficient in removing nitrate, phosphate, cadmium and lead from aqueous solution as compared to other adsorbents already used for the removal of these ions. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. Adsorption of NO on alumina-supported oxides and oxide-hydroxides of manganese.

    PubMed

    Spasova, I; Nikolov, P; Mehandjiev, D

    2005-10-15

    The adsorption capacity for NO of alumina-supported oxides and oxide-hydroxides of manganese have been studied. Two series of samples have been prepared by precipitation on gamma-alumina and appropriate thermal treatment. The samples have been characterized by adsorption methods, magnetic methods, electronic paramagnetic resonance (EPR), transient response technique, and temperature-programmed desorption (TPD). The influence of the concentration of the initial manganese-containing solution has been investigated. The sample, prepared with a solution with Mn concentration of 4 g/100 ml, has been shown to be the best adsorbent for NO under the conditions of the experiment. It has been found that the presence mainly of Mn3+ ions on the surface of the support is probably responsible for the enhanced adsorption capacity.

  2. Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test.

    PubMed

    Nam, Sangchul; Namkoong, Wan; Kang, Jeong-Hee; Park, Jin-Kyu; Lee, Namhoon

    2013-10-01

    Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Fixed-bed column performances of azure-II and auramine-O adsorption by Pinus eldarica stalks activated carbon and its composite with zno nanoparticles: Optimization by response surface methodology based on central composite design.

    PubMed

    Jafari, Maryam; Rahimi, Mahmood Reza; Ghaedi, Mehrorang; Javadian, Hamedreza; Asfaram, Arash

    2017-12-01

    A continuous adsorption was used for removal of azure II (AZ II) and auramine O (AO) from aqueous solutions using Pinus eldarica stalks activated carbon (PES-AC) from aqueous solutions. The effects of initial dye concentration, flow rate, bed height and contact time on removal percentage of AO and AZ II were evaluated and optimized by central composite design (CCD) at optimum pH = 7.0. ZnO nanoparticles loaded on activated carbon were also used to remove AO and AZ II at pH = 7.0 and other optimum conditions. The breakthrough curves were obtained at different flow rates, initial dye concentrations and bed heights and the experimental data were fitted by Thomas, Adams-Bohart and Yoon-Nelson models. The main parameters of fixed-bed column including its adsorption capacity at breakthrough point (q b ), adsorption capacity at saturation point (q s ), mass transfer zone (MTZ), total removal percentage (R%), and empty bed contact time (EBCT) were calculated. The removal percentages calculated for AZ II and AO II were in the range of 51.6-61.1% and 40.6-61.6%, respectively. Bed adsorption capacity (N 0 ) and critical bed depth (Z 0 ) were obtained by BDST model. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Adsorption removal of tannic acid from aqueous solution by polyaniline: Analysis of operating parameters and mechanism.

    PubMed

    Sun, Chencheng; Xiong, Bowen; Pan, Yang; Cui, Hao

    2017-02-01

    Polyaniline (PANI) prepared by chemical oxidation was studied for adsorption removal of tannic acid (TA) from aqueous solution. Batch adsorption studies were carried out under different adsorbent dosages, pH, ionic strength, initial TA concentration and coexisting anions. Solution pH had an important impact on TA adsorption onto PANI with optimal removal in the pH range of 8-11. TA adsorption on PANI at three ionic strength levels (0.02, 0.2 and 2molL -1 NaCl) could be well described by Langmuir model (monolayer adsorption process) and the maximum adsorption capacity was 230, 223 and 1023mgg -1 , respectively. Kinetic data showed that TA adsorption on PANI fitted well with pseudo-second-order model (controlled by chemical process). Among the coexisting anions tested, PO 4 3- significantly inhibited TA adsorption due to the enhancement of repulsive interaction. Continuous flow adsorption studies indicated good flexibility and adaptability of the PANI adsorbent under different flow rates and influent TA concentrations. The mechanism controlling TA adsorption onto PANI under different operating conditions was analyzed with the combination of electrostatic interactions, hydrogen bonding, π-π interactions and Van der Waals interactions. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Adsorption and mineralization of REE-lanthanum onto bacterial cell surface.

    PubMed

    Cheng, Yangjian; Zhang, Li; Bian, Xiaojing; Zuo, Hongyang; Dong, Hailiang

    2017-07-11

    A large number of rare earth element mining and application resulted in a series of problems of soil and water pollution. Environmental remediation of these REE-contaminated sites has become a top priority. This paper explores the use of Bacillus licheniformis to adsorb lanthanum and subsequent mineralization process in contaminated water. The maximum adsorption capacity of lanthanum on bacteria was 113.98 mg/g (dry weight) biomass. X-ray diffraction (XRD) and transmission electron microscopy (TEM) data indicated that adsorbed lanthanum on bacterial cell surface occurred in an amorphous form at the initial stage. Scanning electron microscopy with X-ray energy-dispersive spectroscopy (SEM/EDS) results indicated that lanthanum adsorption was correlated with phosphate. The amorphous material was converted into scorpion-like monazite (LaPO 4 nanoparticles) in a month. The above results provide a method of using bacterial surface as adsorption and nucleation sites to treat REE-contaminated water.

  6. Adsorption of ammonium from simulated wastewater by montmorillonite nanoclay and natural vermiculite: experimental study and simulation.

    PubMed

    Mazloomi, Farhad; Jalali, Mohsen

    2017-08-01

    In this research, montmorillonite nanoclay (MNC) and vermiculite were used to adsorb ammonium (NH 4 + ) from simulated wastewater. The effect of organic acids, cations, and anions on adsorption of NH 4 + was also studied using batch experiments. The presence of organic acids significantly decreased the NH 4 + adsorption using both adsorbents and the reduction followed the order of citric acid > malic acid > oxalic acid. The presence of cations in wastewater could decrease the adsorption of NH 4 + and the ion exchange selectivity on the MNC and vermiculite followed the orders Mg > Ca ≥ K > Na and Mg > > Ca > Na > K, respectively. Adsorption of NH 4 + by adsorbents in the presence of sulfate (SO 4 ) was higher than those in the presence of phosphate (PO 4 ) and chloride (Cl) anions. Results indicated that MNC and vermiculite had good potential for NH 4 + removal depending on adsorbent dosage, pH, contact time, and initial NH 4 + concentration. The effect of pH on removal of NH 4 + indicated that MNC would be more appropriate as the adsorbent than vermiculite at low pH values. Kinetic analysis demonstrated that the rate-controlling step adsorption for NH 4 + by MNC and vermiculite was heterogeneous chemisorption and followed the pseudo-second-order model. The desorption experiments indicated that the adsorption of NH 4 + by adsorbents was not fully reversible, and the total recovery of adsorbed NH 4 + for MNC and vermiculite varied in the range of 72 to 94.6% and 11.5 to 45.7%, respectively. Cation exchange model (CEM) in PHREEQC program was used to simulate NH 4 + adsorption. Agreement between measured and simulated data suggested that CEM was favored in simulating adsorption of NH 4 + by clay minerals. The results indicated that MNC and vermiculite have good performance as economic and nature-friendly adsorbents that can ameliorate the water and environment quality.

  7. Adsorptive removal of bisphenol A using synthesized magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Orimolade, B. O.; Adekola, F. A.; Adebayo, G. B.

    2018-03-01

    Bisphenol A (BPA) is an organic compound which is often used as plasticizer and has been reported to be hazardous to man. In this research the efficiency of removal of BPA from water by magnetite through adsorption process was studied. The magnetite was synthesized using reverse co-precipitation method and fully characterized. Various physicochemical parameters affecting the adsorption of BPA using magnetite were studied as well. The optimum time for the adsorption process was found to be 60 min at pH of 6, adsorbent dose of 0.2 g and 50 ppm of BPA. The adsorption data were fitted by the Langmuir adsorption isotherm best with a regression value of 0.957. The R L value was 0.179 which revealed that the process is favorable. The Freundlich constant n which was 1.901 also revealed that the adsorption is normal and favorable. The data were in agreement with the pseudo-second-order kinetics with regression value of 0.98. From the thermodynamic studies, the process was found to be exothermic and the Gibb's free energy value which was negative showed that the adsorption was spontaneous. The synthesized magnetite therefore offers great potential for the remediation of bisphenol A-contaminated media.

  8. Chromium (Ⅵ) removal from aqueous solutions through powdered activated carbon countercurrent two-stage adsorption.

    PubMed

    Wang, Wenqiang

    2018-01-01

    To exploit the adsorption capacity of commercial powdered activated carbon (PAC) and to improve the efficiency of Cr(VI) removal from aqueous solutions, the adsorption of Cr(VI) by commercial PAC and the countercurrent two-stage adsorption (CTA) process was investigated. Different adsorption kinetics models and isotherms were compared, and the pseudo-second-order model and the Langmuir and Freundlich models fit the experimental data well. The Cr(VI) removal efficiency was >80% and was improved by 37% through the CTA process compared with the conventional single-stage adsorption process when the initial Cr(VI) concentration was 50 mg/L with a PAC dose of 1.250 g/L and a pH of 3. A calculation method for calculating the effluent Cr(VI) concentration and the PAC dose was developed for the CTA process, and the validity of the method was confirmed by a deviation of <5%. Copyright © 2017. Published by Elsevier Ltd.

  9. Adenovirus type 5 intrinsic adsorption rates measured by surface plasmon resonance.

    PubMed

    Roper, D Keith; Nakra, Shamit

    2006-01-01

    Intrinsic adsorption rates of whole adenovirus type 5 (Ad5) onto a diethylaminoethyl (DEAE) anion exchange surface are measured for the first time by surface plasmon resonance (SPR). Fitting SPR sensorgrams to a two-compartment mass transport reaction model distinguishes intrinsic adsorption rates from slow diffusive Ad5 mass transport. Ad5 is a widely used viral vector for gene therapy that binds electrostatically to surfaces of cells and synthetics such as membranes, chromatographic resins, and glass. Increasing NaCl concentration from 4.8 to 14.4mM shifts binding of whole Ad5 from diffusion control to a regime where both sorption and diffusion affect binding. Intrinsic adsorption rates for Ad5-DEAE interaction are 16 times faster than intrinsic adsorption rates for Ad5 fiber knob interacting with soluble extracellular domain of coxsackievirus adenovirus receptors (s-CAR).

  10. Adsorption Characteristics of Bixin on Acid- and Alkali-Treated Kaolinite in Aprotic Solvents

    PubMed Central

    Rahmalia, Winda; Fabre, Jean-François; Usman, Thamrin

    2018-01-01

    The adsorption of bixin in aprotic solvents onto acid- and alkali-treated kaolinite was investigated. Kaolinite was treated three times, for 6 h each, with 8 M HCl or 5 M KOH. The adsorbents were characterized by XRD, FT-IR, EDS, and BET-N2. The effects of contact time and dye concentration on adsorption capacity and kinetics, electronic transition of bixin before and after adsorption, and also mechanism of bixin-kaolinite adsorption were investigated. Dye adsorption followed pseudo-second order kinetics and was faster in acetone than in dimethyl carbonate. The best adsorption results were obtained for KOH-treated kaolinite. In both of the solvents, the adsorption isotherm followed the Langmuir model and adsorption capacity was higher in dimethyl carbonate (q m = 0.43 mg/g) than in acetone (0.29 mg/g). The adsorption capacity and kinetics of KOH-treated kaolinite (q m = 0.43 mg/g, k 2 = 3.27 g/mg·min) were better than those of HCl-treated kaolinite (q m = 0.21 mg/g, k 2 = 0.25 g/mg·min) and natural kaolinite (q m = 0.18 mg/g, k 2 = 0.32 g/mg·min). There are shift in the band position of maximum intensity of bixin after adsorption on this adsorbent. Adsorption in this system seemed to be based essentially on chemisorption due to the electrostatic interaction of bixin with the strong basic and reducing sites of kaolinite. PMID:29581720

  11. Adsorption of emerging contaminant metformin using graphene oxide.

    PubMed

    Zhu, Shuai; Liu, Yun-Guo; Liu, Shao-Bo; Zeng, Guang-Ming; Jiang, Lu-Hua; Tan, Xiao-Fei; Zhou, Lu; Zeng, Wei; Li, Ting-Ting; Yang, Chun-Ping

    2017-07-01

    The occurrence of emerging contaminants in our water resources poses potential threats to the livings. Due to the poor treatment in wastewater management, treatment technologies are needed to effectively remove these products for living organism safety. In this study, Graphene oxide (GO) was tested for the first time for its capacity to remove a kind of emerging wastewater contaminants, metformin. The research was conducted by using a series of systematic adsorption and kinetic experiments. The results indicated that GO could rapidly and efficiently reduce the concentration of metformin, which could provide a solution in handling this problem. The uptake of metformin on the graphene oxide was strongly dependent on temperature, pH, ionic strength, and background electrolyte. The adsorption kinetic experiments revealed that almost 80% removal of metformin was achieved within 20 min for all the doses studied, corresponding to the relatively high k 1 (0.232 min -1 ) and k 2 (0.007 g mg -1  min -1 ) values in the kinetic models. It indicated that the highest adsorption capacity in the investigated range (q m ) of GO for metformin was at pH 6.0 and 288 K. Thermodynamic study indicated that the adsorption was a spontaneous (ΔG 0  < 0) and exothermic (ΔH 0  < 0) process. The adsorption of metformin increased when the pH values changed from 4.0 to 6.0, and decreased adsorption were observed at pH 6.0-11.0. GO still exhibited excellent adsorption capacity after several desorption/adsorption cycles. Besides, both so-called π-π interactions and hydrogen bonds might be mainly responsible for the adsorption of metformin onto GO. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Toward Accurate Adsorption Energetics on Clay Surfaces

    PubMed Central

    2016-01-01

    Clay minerals are ubiquitous in nature, and the manner in which they interact with their surroundings has important industrial and environmental implications. Consequently, a molecular-level understanding of the adsorption of molecules on clay surfaces is crucial. In this regard computer simulations play an important role, yet the accuracy of widely used empirical force fields (FF) and density functional theory (DFT) exchange-correlation functionals is often unclear in adsorption systems dominated by weak interactions. Herein we present results from quantum Monte Carlo (QMC) for water and methanol adsorption on the prototypical clay kaolinite. To the best of our knowledge, this is the first time QMC has been used to investigate adsorption at a complex, natural surface such as a clay. As well as being valuable in their own right, the QMC benchmarks obtained provide reference data against which the performance of cheaper DFT methods can be tested. Indeed using various DFT exchange-correlation functionals yields a very broad range of adsorption energies, and it is unclear a priori which evaluation is better. QMC reveals that in the systems considered here it is essential to account for van der Waals (vdW) dispersion forces since this alters both the absolute and relative adsorption energies of water and methanol. We show, via FF simulations, that incorrect relative energies can lead to significant changes in the interfacial densities of water and methanol solutions at the kaolinite interface. Despite the clear improvements offered by the vdW-corrected and the vdW-inclusive functionals, absolute adsorption energies are often overestimated, suggesting that the treatment of vdW forces in DFT is not yet a solved problem. PMID:27917256

  13. Characterization and evaluation of amorphous carbon thin film (ACTF) for sodium ion adsorption

    NASA Astrophysics Data System (ADS)

    Fathy, Mahmoud; Mousa, Mahmoud Ahmed; Moghny, Th. Abdel; Awadallah, Ahmed E.

    2017-12-01

    The removal of sodium ions from aqueous solutions by adsorption onto amorphous carbon thin film (ACTF) has been studied in batch mode. In this work, the ACTF as new adsorbent was synthesized based on rice straw, then its structure and properties were taken into consideration to study its ability to adsorb sodium ions from synthetic water. The influence of pH, contact time, and temperature of the ion adsorption on ACTF was also studied using batch tests. We found that the contact time of sodium adsorption and its isothermal adsorption studied were described by pseudo-second-order kinetic model and Langmuir isotherm, respectively. Our results indicated that the adsorption of sodium ions on ACTF become be stronger and depends on pH, furthermore, the maximum adsorption capacities of sodium on ACTF recorded 107, 120 and 135 mg g-1 at 35, 45, and 65 °C. The thermodynamic parameters explain that the adsorption of sodium ions on ACTF is a spontaneous process and endothermic reaction. According to adsorption studies, we found that the ACTF can be used effectively for ion chromatography or desalinate sodium ion using ion exchange process in the hybrid desalination process with insignificant loss of adsorption capacity. However, the ACTF has better properties than any other carbon materials obtained from an agricultural byproduct.

  14. Characterization of biochars derived from agriculture wastes and their adsorptive removal of atrazine from aqueous solution: A comparative study.

    PubMed

    Liu, Na; Charrua, Alberto Bento; Weng, Chih-Huang; Yuan, Xiaoling; Ding, Feng

    2015-12-01

    The physicochemical properties of biochars produced from soybeans (SBB), corn stalks (CSB), rice stalks (RSB), poultry manure (PMB), cattle manure (CMB), and pig manure (PgMB) and their adsorption characteristics of atrazine were investigated. The adsorption capacity increased with the increase of temperature and initial atrazine concentration. More atrazine was removed from basic solutions than acidic solutions, due to the effects of adsorption and hydrolysis. The Freundlich isotherm adsorption parameters indicated that the adsorption capacity decreased in the order SBB>RSB>CMB>CSB>PMB>PgMB, which is associated to the pore volume of biochars. The total pore volume and biochar pH were concluded to play important roles in determining the adsorption capacity, and they may have contributed to physical adsorption mechanisms dominating the overall adsorption process (the low activation energy for all of the biochars). Modified Freundlich and intraparticle diffusion models were used to describe the kinetics of the adsorption process. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Adsorption of dyes using different types of clay: a review

    NASA Astrophysics Data System (ADS)

    Adeyemo, Aderonke Ajibola; Adeoye, Idowu Olatunbosun; Bello, Olugbenga Solomon

    2017-05-01

    Increasing amount of dyes in the ecosystem particularly in wastewater has propelled the search for more efficient low-cost adsorbents. The effective use of the sorption properties (high surface area and surface chemistry, lack of toxicity and potential for ion exchange) of different clays as adsorbents for the removal of different type of dyes (basic, acidic, reactive) from water and wastewater as potential alternatives to activated carbons has recently received widespread attention because of the environmental-friendly nature of clay materials. Insights into the efficiencies of raw and modified/activated clay adsorbents and ways of improving their efficiencies to obtain better results are discussed. Acid-modified clay resulted in higher rate of dye adsorption and an increased surface area and porosity (49.05 mm2 and 53.4 %). Base-modified clay has lower adsorption capacities, while ZnCl2-modified clay had the least rate of adsorption with a surface area of 44.3 mm2 and porosity of 43.4 %. This review also explores the grey areas of the adsorption properties of the raw clays and the improved performance of activated/modified clay materials with particular reference to the effects of pH, temperature, initial dye concentration and adsorbent dosage on the adsorption capacities of the clays. Various challenges encountered in using clay materials are highlighted and a number of future prospects for the adsorbents are proposed.

  16. Hydrophilic crosslinked-polymeric surface capable of effective suppression of protein adsorption

    NASA Astrophysics Data System (ADS)

    Kamon, Yuri; Inoue, Naoko; Mihara, Erika; Kitayama, Yukiya; Ooya, Tooru; Takeuchi, Toshifumi

    2016-08-01

    We investigated the nonspecific adsorption of proteins towards three hydrophilic crosslinked-polymeric thin layers prepared by surface-initiated atom transfer radical polymerization using N,N‧-methylenebisacrylamide, 2-(methacryloyloxy)ethyl-[N-(2-methacryloyloxy)ethyl]phosphorylcholine (MMPC), or 6,6‧-diacryloyl-trehalose crosslinkers. Protein binding experiments were performed by surface plasmon resonance with six proteins of different pI values including α-lactalbumin, bovine serum albumin (BSA), myoglobin, ribonuclease A, cytochrome C, and lysozyme in buffer solution at pH 7.4. All of the obtained crosslinked-polymeric thin layers showed low nonspecific adsorption of negatively charged proteins at pH 7.4 such as α-lactalbumin, BSA, and myoglobin. Nonspecific adsorption of positively charged proteins including ribonuclease A, cytochrome C, and lysozyme was the lowest for poly(MMPC). These results suggest poly(MMPC) can effectively reduce nonspecific adsorption of a wide range of proteins that are negatively or positively charged at pH 7.4. MMPC is a promising crosslinker for a wide range of polymeric materials requiring low nonspecific protein binding.

  17. Polymyxin B immobilized on cross-linked cellulose microspheres for endotoxin adsorption.

    PubMed

    Cao, Xiaodong; Zhu, Biyan; Zhang, Xufeng; Dong, Hua

    2016-01-20

    Cross-linked cellulose microspheres (CL-CMs) were successfully prepared by inverse crosslinking suspension method. NaOH/urea aqueous solution was used as solvent to dissolve cellulose at low temperature. The microspheres presented good spherical shape and monodispersity, which were applied to synthesize endotoxin adsorbent with polymyxin B (PMB) as ligand. The adsorbent showed good adsorption capability on endotoxin in physiologic saline solution and the maximum adsorption capacity was 3605 EU/g (1 EU=100 pg). It was worth noting that more than 70% of endotoxin could be effectively removed from the human plasma with the initial concentration of endotoxin ranged from 1 EU/mL to 5 EU/mL. The dynamic adsorption efficiency of endotoxin was 72.3% at the plasma perfusion rate of 300 mL/h with the endotoxin concentration of 4 EU/mL, while the variation of plasma protein before and after adsorption was only 8.9%. It suggests that the PMB immobilized CL-CMs have great potential application in clinical blood purification. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Adsorption of Ni(II) onto Chemically Modified Spent Grated Coconut (Cocos Nucifera)

    NASA Astrophysics Data System (ADS)

    Hamzah, F. I.; Khalid, K.; Hanafiah, M. A. K. M.

    2017-06-01

    A new adsorbent of plant waste origin from coconut processing food factory was explored for removing Ni(II) from aqueous solutions. Several parameters such as pH, dosage, concentration and contact time were studied to obtain optimum conditions for treatment of Ni(II) contaminated wastewater. Spent grated coconut (Cocos nucifera) treated with sulfuric acid (SSGC) showed good adsorption capacity for Ni(II) ion. The amount adsorbed was affected by solution pH with the highest value achieved at pH 5. Other optimum conditions found were; dosage of 0.02 g, and 60 min of equilibrium time. Ni(II) adsorption obeyed the pseudo-second order kinetic model which suggested that chemisorption mechanism occurred in the adsorption process. The equilibrium data presented a better fitting to the Langmuir isotherm model, an indication that monolayer adsorption occurred onto a homogeneous surface. The maximum adsorption capacity, qmax was 97.09 mg g-1, thus SSGC can be classified as good and comparable with other plant waste adsorbents.

  19. Adsorption Study on Moringa Oleifera Seeds and Musa Cavendish as Natural Water Purification Agents for Removal of Lead, Nickel and Cadmium from Drinking Water

    NASA Astrophysics Data System (ADS)

    Aziz, N. A. A.; Jayasuriya, N.; Fan, L.

    2016-07-01

    The effectiveness of plant based materials Moringa oleifera (Moringa) seeds and Musa cavendish (banana peel) for removing heavy metals namely lead (Pb), nickel (Ni) and cadmium (Cd) from contaminated groundwater was studied. Tests were carried out with individual and combined biomass at neutral pH condition on synthetic groundwater samples. The optimum biomass doses were determined as 200 mg/L for single biomass and 400 mg/L (in the ratio of 200 mg/L: 200 mg/L) for combined biomasses and used for adsorption isotherm studies with contact time of 30 minutes. Results showed that combined biomasses was able to met the Pb, Ni and Cd WHO standards from higher Pb, Ni and Cd initial concentrations which were up to 40 µg/L, 50 µg/L 9 µg/L, respectively compared to individual biomass of Moringa seed and banana peel. Moringa seeds exhibited the highest removal of Pb (81%) while the combined biomasses was most effective in removing Ni (74%) and Cd (97%) over wider their initial concentration ranges. The experimental data were linearized with Langmuir and Freundlich adsorption isotherm models. Freundlich model described the Pb adsorption better than the Langmuir model for all the tested biomasses. However, the Langmuir model fit better with the experimental data of Ni adsorption by Moringa seeds. Both models showed negligible differences in the coefficient of determination (R2) when applied for Ni and Cd adsorption on banana peel and combined biomasses, suggesting that there were multiple layers on the biomass interacting with the metals. Chemisorption is suggested to be involved in Pb adsorption for all tested biomasses as the value of nF calculated was lower than one. This type of adsorption could explain the phenomenon of different behavior of Pb removal and the higher Pb adsorption capacity (represented by KF values) compared to Ni and Cd. The study demonstrates that Moringa seeds, banana peel and their combination have the potential to be used as a natural alternative

  20. Adsorption of Pb(II) and Cu(II) by Ginkgo-Leaf-Derived Biochar Produced under Various Carbonization Temperatures and Times.

    PubMed

    Lee, Myoung-Eun; Park, Jin Hee; Chung, Jae Woo

    2017-12-07

    Ginkgo trees are common street trees in Korea, and the large amounts of leaves that fall onto the streets annually need to be cleaned and treated. Therefore, fallen gingko leaves have been used as a raw material to produce biochar for the removal of heavy metals from solutions. Gingko-leaf-derived biochar was produced under various carbonization temperatures and times. This study evaluated the physicochemical properties and adsorption characteristics of gingko-leaf-derived biochar samples produced under different carbonization conditions regarding Pb(II) and Cu(II). The biochar samples that were produced at 800 °C for 90 and 120 min contained the highest oxygen- and nitrogen-substituted carbons, which might contribute to a high metal-adsorption rate. The intensity of the phosphate bond was increased with the increasing of the carbonization temperature up to 800 °C and after 90 min of carbonization. The Pb(II) and Cu(II) adsorption capacities were the highest when the gingko-leaf-derived biochar was produced at 800 °C, and the removal rates were 99.2% and 34.2%, respectively. The highest removal rate was achieved when the intensity of the phosphate functional group in the biochar was the highest. Therefore, the gingko-leaf-derived biochar produced at 800 °C for 90 min can be used as an effective bio-adsorbent in the removal of metals from solutions.

  1. Adsorption Removal of Environmental Hormones of Dimethyl Phthalate Using Novel Magnetic Adsorbent.

    PubMed

    Chang, Chia-Chi; Tseng, Jyi-Yeong; Ji, Dar-Ren; Chiu, Chun-Yu; Lu, De-Sheng; Chang, Ching-Yuan; Yuan, Min-Hao; Chang, Chiung-Fen; Chiou, Chyow-San; Chen, Yi-Hung; Shie, Je-Lueng

    2015-01-01

    Magnetic polyvinyl alcohol adsorbent M-PVAL was employed to remove and concentrate dimethyl phthalate DMP. The M-PVAL was prepared after sequential syntheses of magnetic Fe3O4 (M) and polyvinyl acetate (M-PVAC). The saturated magnetizations of M, M-PVAC, and M-PVAL are 57.2, 26.0, and 43.2 emu g(-1) with superparamagnetism, respectively. The average size of M-PVAL by number is 0.75 μm in micro size. Adsorption experiments include three cases: (1) adjustment of initial pH (pH0) of solution to 5, (2) no adjustment of pH0 with value in 6.04-6.64, and (3) adjusted pH0 = 7. The corresponding saturated amounts of adsorption of unimolecular layer of Langmuir isotherm are 4.01, 5.21, and 4.22 mg g(-1), respectively. Values of heterogeneity factor of Freundlich isotherm are 2.59, 2.19, and 2.59 which are greater than 1, revealing the favorable adsorption of DMP/M-PVAL system. Values of adsorption activation energy per mole of Dubinin-Radushkevich isotherm are, respectively, of low values of 7.04, 6.48, and 7.19 kJ mol(-1), indicating the natural occurring of the adsorption process studied. The tiny size of adsorbent makes the adsorption take place easily while its superparamagnetism is beneficial for the separation and recovery of micro adsorbent from liquid by applying magnetic field after completion of adsorption.

  2. Effect of degree of deacetylation of chitosan on adsorption capacity and reusability of chitosan/polyvinyl alcohol/TiO2 nano composite.

    PubMed

    Habiba, Umma; Joo, Tan Chin; Siddique, Tawsif A; Salleh, Areisman; Ang, Bee Chin; Afifi, Amalina M

    2017-11-01

    The chitosan/polyvinyl alcohol/TiO 2 composite was synthesized. Two different degrees of deacetylation of chitosan were prepared by hydrolysis to compare the effectiveness of them. The composite was analyzed via field emission scanning electron microscopy, Fourier transform infrared, X-ray diffraction, thermal gravimetric analysis, weight loss test and adsorption study. The FTIR and XRD results proved the interaction among chitosan, PVA and TiO 2 without any chemical reaction. It was found that, chitosan with higher degree of deacetylation has better stability. Furthermore, it also showed that higher DD of chitosan required less time to reach equilibrium for methyl orange. The adsorption followed the pseudo-second-order kinetic model. The Langmuir and Freundlich isotherm models were fitted well for isotherm study. Adsorption capacity was higher for the composite containing chitosan with higher DD. The dye removal rate was independent of the dye's initial concentration. The adsorption capacity was increased with temperature and it was found from reusability test that the composite containing chitosan with higher DD is more reusable. It was notable that adsorption capacity was even after 15 runs. Therefore, chitosan/PVA/TiO 2 composite can be a very useful material for dye removal. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Adsorption of heavy metals from aqueous solutions by Mg-Al-Zn mingled oxides adsorbent.

    PubMed

    El-Sayed, Mona; Eshaq, Gh; ElMetwally, A E

    2016-10-01

    In our study, Mg-Al-Zn mingled oxides were prepared by the co-precipitation method. The structure, composition, morphology and thermal stability of the synthesized Mg-Al-Zn mingled oxides were analyzed by powder X-ray diffraction, Fourier transform infrared spectrometry, N 2 physisorption, scanning electron microscopy, differential scanning calorimetry and thermogravimetry. Batch experiments were performed to study the adsorption behavior of cobalt(II) and nickel(II) as a function of pH, contact time, initial metal ion concentration, and adsorbent dose. The maximum adsorption capacity of Mg-Al-Zn mingled oxides for cobalt and nickel metal ions was 116.7 mg g -1 , and 70.4 mg g -1 , respectively. The experimental data were analyzed using pseudo-first- and pseudo-second-order kinetic models in linear and nonlinear regression analysis. The kinetic studies showed that the adsorption process could be described by the pseudo-second-order kinetic model. Experimental equilibrium data were well represented by Langmuir and Freundlich isotherm models. Also, the maximum monolayer capacity, q max , obtained was 113.8 mg g -1 , and 79.4 mg g -1 for Co(II), and Ni(II), respectively. Our results showed that Mg-Al-Zn mingled oxides can be used as an efficient adsorbent material for removal of heavy metals from industrial wastewater samples.

  4. [Adsorption kinetics and mechanism of lead (II) on polyamine-functionalized mesoporous activated carbon].

    PubMed

    Li, Kun-Quan; Wang, Yan-Jin; Yang, Mei-Rong; Zhu, Zhi-Qiang; Zheng, Zheng

    2014-08-01

    Bagasse mesoporous carbon was prepared by microwave assisted H3 PO4 activation. Amido and imido groups were modified with ethanediamine on the channels' surface of mesoporous carbon through nitric oxidation and amide reaction. The influence of Pb(II) concentration, adsorption time on Pb(II) adsorption on the ethanediamine-modified mesoporous carbon (AC-EDA) was investigated. The adsorption kinetics and mechanism were also discussed. The results showed that AC-EDA had a great performance for Pb(II) adsorption, and more than 70% of Pb(II) was adsorbed in 5 minutes. The adsorption amount of Pb(II) on the carbon increased with the increase of solution pH in acidic conditions. It was found that AC-EDA had different binding energies on different adsorption sites for Pb(II) separation. The Pb(II) adsorption process on AC-EDA was controlled by intra-particle diffusion in the first 3 min, and then film diffusion played the important pole on the adsorption. The adsorption amount increased with the increase of temperature, indicating the adsorption was an endothermic reaction. The high adsorption energy (> 11 kJ x mol(-1)) implied that the) adsorption was a chemical adsorption. The XPS of AC-EDA before and after Pb(II) adsorption showed that the polyamine group was involved in the adsorption, and should be a main factor of the high efficient adsorption.

  5. Time-dependent importance sampling in semiclassical initial value representation calculations for time correlation functions.

    PubMed

    Tao, Guohua; Miller, William H

    2011-07-14

    An efficient time-dependent importance sampling method is developed for the Monte Carlo calculation of time correlation functions via the initial value representation (IVR) of semiclassical (SC) theory. A prefactor-free time-dependent sampling function weights the importance of a trajectory based on the magnitude of its contribution to the time correlation function, and global trial moves are used to facilitate the efficient sampling the phase space of initial conditions. The method can be generally applied to sampling rare events efficiently while avoiding being trapped in a local region of the phase space. Results presented in the paper for two system-bath models demonstrate the efficiency of this new importance sampling method for full SC-IVR calculations.

  6. Research of combined adsorption-coagulation process in treating petroleum refinery effluent.

    PubMed

    Wang, Bing; Shui, Yiyu; Ren, Hongyang; He, Min

    2017-02-01

    The petroleum refinery industry generates a significant amount of wastewater that contains a high level of organic matter, which calls for effective and costly treatments. In this research, the effectiveness of the petroleum refinery effluent (PRE) treatment with physicochemical process of combined adsorption and coagulation was evaluated. The effects of initial pH, hydraulic condition , and combined sequence of treatment process, different treating reagent types and dosages on the chemical oxygen demand (COD) removal were investigated. Additionally, the elimination efficiency of pollutant wastewater was monitored by gas chromatography-mass spectrometry (GC-MS), and Fourier transformed infrared (FT-IR) spectrophotometer was adopted to describe the structure of the wastewater. Wooden activated carbon was chosen as adsorbent at the dosage of 10 g/L as a primary treatment, and 1500 mg/L polymeric magnesium ferric sulfate was used in coagulation. Results showed that adsorption and subsequent coagulation displayed the best performance when initial pH was 9 at shear rates (G) of G1 = 65 s -1 and G2 = 20 s -1 , which reached maximal removal rate of COD and total organic carbon GC-MS testing result revealed that adsorption was effective in phenols and iso-alkanes removal, whereas coagulation was good at removing esters and n-alkanes.

  7. Macroscopic and Microscopic Investigation of U(VI) and Eu(III) Adsorption on Carbonaceous Nanofibers.

    PubMed

    Sun, Yubing; Wu, Zhen-Yu; Wang, Xiangxue; Ding, Congcong; Cheng, Wencai; Yu, Shu-Hong; Wang, Xiangke

    2016-04-19

    The adsorption mechanism of U(VI) and Eu(III) on carbonaceous nanofibers (CNFs) was investigated using batch, IR, XPS, XANES, and EXAFS techniques. The pH-dependent adsorption indicated that the adsorption of U(VI) on the CNFs was significantly higher than the adsorption of Eu(III) at pH < 7.0. The maximum adsorption capacity of the CNFs calculated from the Langmuir model at pH 4.5 and 298 K for U(VI) and Eu(III) were 125 and 91 mg/g, respectively. The CNFs displayed good recyclability and recoverability by regeneration experiments. Based on XPS and XANES analyses, the enrichment of U(VI) and Eu(III) was attributed to the abundant adsorption sites (e.g., -OH and -COOH groups) of the CNFs. IR analysis further demonstrated that -COOH groups were more responsible for U(VI) adsorption. In addition, the remarkable reducing agents of the R-CH2OH groups were responsible for the highly efficient adsorption of U(VI) on the CNFs. The adsorption mechanism of U(VI) on the CNFs at pH 4.5 was shifted from inner- to outer-sphere surface complexation with increasing initial concentration, whereas the surface (co)precipitate (i.e., schoepite) was observed at pH 7.0 by EXAFS spectra. The findings presented herein play an important role in the removal of radionuclides on inexpensive and available carbon-based nanoparticles in environmental cleanup applications.

  8. Adsorption of phosphate in water using one-step synthesized zirconium-loaded reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Luo, Xin; Wang, Xiurong; Bao, Shaopan; Liu, Xiawei; Zhang, Weicheng; Fang, Tao

    2016-12-01

    In this account, a one-step green hydrothermal method for zirconium-loaded reduced graphene oxide (RGO-Zr) adsorbent was developed in pure water. It is based on the formation of initially strong-coupling RGO-Zr nanocomposites followed by in situ reduction of GO to RGO during the hydrothermal treatment. The phosphate adsorption performance of the as-prepared nanocomposites was investigated in aqueous environment under various conditions. The characterization results of RGO-Zr nanocomposites showed that ZrO2 was successfully integrated onto the RGO sheets in amorphous. The data from equilibrium phosphate adsorption on RGO-Zr revealed that the adsorption kinetics followed a pseudo-second-order kinetic model, where the adsorption isotherm fitted the Langmuir isotherm model with a maximum adsorption capacity of 27.71 mg P/g at pH 5 and 298 K. The improved phosphate adsorption on RGO-Zr was caused by the dispersion of ZrO2 on the RGO surface. Furthermore, the phosphate adsorption was found insensitive to the increase in pH while it was sensitive to the increase in temperature. The coexisting anions of SO42-, F-, Cl-, NO3- and CO32- affected the phosphate adsorption in a different way. Results suggest that the present RGO-Zr adsorbent has the potential for controlling phosphorus pollution in water.

  9. Study of gas adsorption on as-produced and modified carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Rawat, Dinesh Singh

    Volumetric adsorption isotherm measurements were used to study the adsorption characteristics of Ethane (C2H6) and Butane (C 4H10) on as-produced single-walled carbon nanotubes. The binding energy of the adsorbed alkane molecule was found to increase with increasing carbon chain length. Two adsorption substeps were obtained for each alkane molecule. However, the size of the high pressure substep was found to be gradually smearing with the increase in size of the adsorbed molecule. This phenomenon is interpreted as size entropy effect for linear molecules. This interpretation was also verified by determining the specific surface area of the substrate using linear molecules of different sizes. Kinetics measurements of alkane adsorption on SWNTs were also conducted and their dependence on the molecular length was determined. Similar adsorption measurements were performed for Argon (Ar) on as-produced single-walled carbon nanotubes and nanotubes that were structurally modified using acid treatment. Enhancement of the sorptive capacity and the presence of two distinct kinetics of gas adsorption verified partial opening of single walled carbon nanotubes as a result of chemical treatment. Mutiwalled carbon nanotubes were exposed to oxygen plasma treatment for varying time periods. Afterwards, adsorption measurements of Methane (CH 4) were conducted on untreated and oxygen plasma treated tubes. The presence of an additional substep, after exposing multiwalled carbon nanotubes to oxygen plasma for varying time periods, suggested progressive cleaning of nanotube surface.

  10. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash.

    PubMed

    Liu, Minmin; Hou, Li-An; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-05-15

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29 Si and 27 Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin-Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics.

  11. Molecular dynamics simulations of collagen adsorption onto grooved rutile surface: the effects of groove width.

    PubMed

    Chen, Mingjun; Zheng, Ting; Wu, Chunya; Xing, Cheng

    2014-09-01

    The early adsorption stages of collagen onto nano-grooved rutile surface without hydroxylation were studied using molecular dynamics and steered MD simulations. On the basis of plane rutile (110), two kinds of models have been adopted: single groove and parallel grooves along [1-11] crystal orientation with various width dimensions. Initially, collagens were parallel or perpendicular to the groove orientation, respectively, in order to investigate the influence of groove width on collagen adsorption. The simulation result suggests that surface grooves could exert a strong effect on collagen adsorption: when collagen was parallel to the groove direction, adsorption was favored if the groove width matched well with the dimension of collagen. However, adsorption strength may decrease as the groove width expanded. As for the condition of collagen perpendicular to the groove orientation, collagen was difficult to bend and insert into grooves in the free adsorption procedure. But the steered MD simulation results reveal that more energy was consumed for collagen to insert into narrower grooves which may be interpreted as strong barrier for adsorption. We believe that adsorption will be favored if appropriate dimension match between dimension of collagen and the groove width was approached. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Adsorptive removal of Lead from water by the effective and reusable magnetic cellulose nanocomposite beads entrapping activated bentonite.

    PubMed

    Luo, Xiaogang; Lei, Xiaojuan; Xie, Xiuping; Yu, Bo; Cai, Ning; Yu, Faquan

    2016-10-20

    Many efforts have been driven to decontaminate the drinking water, and the development of efficient adsorbents with the advantages of cost-effectiveness and operating convenience for the removal of Pb(2+) from water is a major challenge. This work was aimed to explore the possibility of using cellulose-based adsorbents for efficient adsorption of Pb(2+). The millimeter-scale magnetic cellulose-based nanocomposite beads were fabricated via an optimal extrusion dropping technology by blending cellulose with the carboxyl-functionalized magnetite nanoparticles and acid-activated bentonite in NaOH/urea aqueous solution, and then they had been tested to evaluate the effectiveness in the removal of Pb(2+) from water. The effects of contact time, initial heavy metal ion concentrations, adsorption isotherms and solution pH on the sorption behavior were studied. The thermodynamic parameters (ΔG, ΔH and ΔS) indicated that the adsorption processes were feasible, spontaneous, endothermic and mainly controlled by chemical mechanisms. The reusability of the adsorbent was also studied. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Surface rheology of saponin adsorption layers.

    PubMed

    Stanimirova, R; Marinova, K; Tcholakova, S; Denkov, N D; Stoyanov, S; Pelan, E

    2011-10-18

    Extracts of the Quillaja saponaria tree contain natural surfactant molecules called saponins that very efficiently stabilize foams and emulsions. Therefore, such extracts are widely used in several technologies. In addition, saponins have demonstrated nontrivial bioactivity and are currently used as essential ingredients in vaccines, food supplements, and other health products. Previous preliminary studies showed that saponins have some peculiar surface properties, such as a very high surface modulus, that may have an important impact on the mechanisms of foam and emulsion stabilization. Here we present a detailed characterization of the main surface properties of highly purified aqueous extracts of Quillaja saponins. Surface tension isotherms showed that the purified Quillaja saponins behave as nonionic surfactants with a relatively high cmc (0.025 wt %). The saponin adsorption isotherm is described well by the Volmer equation, with an area per molecule of close to 1 nm(2). By comparing this area to the molecular dimensions, we deduce that the hydrophobic triterpenoid rings of the saponin molecules lie parallel to the air-water interface, with the hydrophilic glucoside tails protruding into the aqueous phase. Upon small deformation, the saponin adsorption layers exhibit a very high surface dilatational elasticity (280 ± 30 mN/m), a much lower shear elasticity (26 ± 15 mN/m), and a negligible true dilatational surface viscosity. The measured dilatational elasticity is in very good agreement with the theoretical predictions of the Volmer adsorption model (260 mN/m). The measured characteristic adsorption time of the saponin molecules is 4 to 5 orders of magnitude longer than that predicted theoretically for diffusion-controlled adsorption, which means that the saponin adsorption is barrier-controlled around and above the cmc. The perturbed saponin layers relax toward equilibrium in a complex manner, with several relaxation times, the longest of them being around 3

  14. Hydrogen adsorption and diffusion, and subcritical-crack growth in high strength steels and nickel base alloys

    NASA Technical Reports Server (NTRS)

    Wei, R. P.; Klier, K.; Simmons, G. W.; Chornet, E.

    1973-01-01

    Embrittlement, or the enhancement of crack growth by gaseous hydrogen in high strength alloys, is of primary interest in selecting alloys for various components in the space shuttle. Embrittlement is known to occur at hydrogen gas pressures ranging from fractions to several hundred atmospheres, and is most severe in the case of martensitic high strength steels. Kinetic information on subcritical crack growth in gaseous hydrogen is sparse at this time. Corroborative information on hydrogen adsorption and diffusion is inadequate to permit a clear determination of the rate controlling process and possible mechanism in hydrogen enhanced crack growth, and for estimating behavior over a range of temperatures and pressures. Therefore, coordinated studies of the kinetics of crack growth, and adsorption and diffusion of hydrogen, using identical materials, have been initiated. Comparable conditions of temperature and pressure will be used in the chemical and mechanical experiments. Inconel 718 alloy and 18Ni(200) maraging steel have been selected for these studies. Results from these studies are expected to provide not only a better understanding of the gaseous hydrogen embrittlement phenomenon itself, but also fundamental information on hydrogen adsorption and diffusion, and crack growth information that can be used directly for design.

  15. Molybdenum isotope fractionation during adsorption to organic matter

    USGS Publications Warehouse

    King, Elizabeth K.; Perakis, Steven; Pett-Ridge, Julie C.

    2018-01-01

    Organic matter is of emerging interest as a control on molybdenum (Mo) biogeochemistry, and information on isotope fractionation during adsorption to organic matter can improve interpretations of Mo isotope variations in natural settings. Molybdenum isotope fractionation was investigated during adsorption onto insolubilized humic acid (IHA), a surrogate for organic matter, as a function of time (2–170 h) and pH (2–7). For the time series experiment performed at pH 4.2, the average Mo isotope fractionation between the solution and the IHA (Δ98Mosolution-IHA) was 1.39‰ (± 0.16‰, 2σ, based on 98Mo/95Mo relative to the NIST 3134 standard) at steady state. For the pH series experiment, Mo adsorption decreased as pH increased from 2.0 to 6.9, and the Δ98Mosolution-IHA increased from 0.82‰ to 1.79‰. We also evaluated natural Mo isotope patterns in precipitation, foliage, organic horizon, surface mineral soil, and bedrock from 12 forested sites in the Oregon Coast Range. The average Mo isotope offset observed between precipitation and organic (O) horizon soil was 2.1‰, with light Mo isotopes adsorbing preferentially to organic matter. Fractionation during adsorption to organic matter is similar in magnitude and direction to prior observations of Mo fractionation during adsorption to Fe- and Mn- (oxyhydr)oxides. Our finding that organic matter influences Mo isotope composition has important implications for the role of organic matter as a driver of trace metal retention and isotopic fractionation.

  16. Molybdenum isotope fractionation during adsorption to organic matter

    NASA Astrophysics Data System (ADS)

    King, E. K.; Perakis, S. S.; Pett-Ridge, J. C.

    2018-02-01

    Organic matter is of emerging interest as a control on molybdenum (Mo) biogeochemistry, and information on isotope fractionation during adsorption to organic matter can improve interpretations of Mo isotope variations in natural settings. Molybdenum isotope fractionation was investigated during adsorption onto insolubilized humic acid (IHA), a surrogate for organic matter, as a function of time (2-170 h) and pH (2-7). For the time series experiment performed at pH 4.2, the average Mo isotope fractionation between the solution and the IHA (Δ98Mosolution-IHA) was 1.39‰ (±0.16‰, 2σ, based on 98Mo/95Mo relative to the NIST 3134 standard) at steady state. For the pH series experiment, Mo adsorption decreased as pH increased from 2.0 to 6.9, and the Δ98Mosolution-IHA increased from 0.82‰ to 1.79‰. We also evaluated natural Mo isotope patterns in precipitation, foliage, organic horizon, surface mineral soil, and bedrock from 12 forested sites in the Oregon Coast Range. The average Mo isotope offset observed between precipitation and organic (O) horizon soil was 2.1‰, with light Mo isotopes adsorbing preferentially to organic matter. Fractionation during adsorption to organic matter is similar in magnitude and direction to prior observations of Mo fractionation during adsorption to Fe- and Mn- (oxyhydr)oxides. Our finding that organic matter influences Mo isotope composition has important implications for the role of organic matter as a driver of trace metal retention and isotopic fractionation.

  17. An experimental design approach for modeling As(V) adsorption from aqueous solution by activated carbon.

    PubMed

    Bakkal Gula, C; Bilgin Simsek, E; Duranoglu, D; Beker, U

    2015-01-01

    The present paper discusses response surface methodology as an efficient approach for predictive model building and optimization of As(V) adsorption on activated carbon derived from a food industry waste: peach stones. The objectives of the study are application of a three-factor 2³ full factorial and central composite design technique for maximizing As(V) removal by produced activated carbon, and examination of the interactive effects of three independent variables (i.e., solution pH, temperature, and initial concentration) on As(V) adsorption capacity. Adsorption equilibrium was investigated by using Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models. First-order and second-order kinetic equations were used for modeling of adsorption kinetics. Thermodynamic parameters (ΔG °, ΔH °, and ΔS °) were calculated and used to explain the As(V) adsorption mechanism. The negative value of ΔH (-7.778 kJ mol⁻¹) supported the exothermic nature of the sorption process and the Gibbs free energy values (ΔG°) were found to be negative, which indicates that the As(V) adsorption is feasible and spontaneous.

  18. Adsorption of NH4+-N on Chinese loess: Non-equilibrium and equilibrium investigations.

    PubMed

    Xie, Haijian; Wang, Shaoyi; Qiu, Zhanhong; Jiang, Jianqun

    2017-11-01

    NH 4 + -N is a crucial pollutant in landfill leachate and can be in high concentrations for a long period of time due to anaerobic condition of landfills. The adsorption properties of NH 4 + -N on the Chinese loess were investigated using Batch test. The influences of ammonium concentration, temperature, reaction time, slurry concentration, and pH on the adsorption process are evaluated. Adsorption kinetics and isotherm behaviors were studied by applying different models to the test data to determine the adsorption parameters. The equilibrating duration was shown to be less than 60 min. The data on adsorption kinetics can be well fitted by the pseudo-second-order kinetics model. According to the Langmuir isotherm model, the adsorption capacity of Chinese loess about NH 4 + -N was predicted to be 72.30 mg g -1 . The uptake of NH 4 + -N by Chinese loess was considered to be the type of physical adsorption on the basis of D-R isotherm analysis. The optimal pH and slurry concentration are 4 and 2 g/50 ml, respectively. According to the calculated values of free energy, enthalpy and entropy change, the adsorption process is determined to be exothermic. The disorder of the system appeared lowest at temperature of 308.15 K. The predicted Gibb's free energies also indicate the adsorption process is endothermic and spontaneous. The FTIR spectrum and EDX analysis showed the adsorption process of NH 4 + involves cation exchange and dissolution of calcite. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. [Characteristic of ammonia nitrogen adsorption on karst underground river sediments].

    PubMed

    Guo, Fang; Chen, Kun-Kun; Jiang, Guang-Hui

    2011-02-01

    Karst aquifers are one of the most important aquifers in Southwestern China. One of the characteristics of karst aquifers is the enhanced permeability permits high flow velocities are capable of transporting suspended and bedload sediments. Mobile sediment in karst may act as a vector for the transport of contaminates. 14 sediment samples were collected from two underground rivers in two typical karst areas in Liuzhou city, Guangxi Autonomous Region, China. According to simulated experiment methods, characteristic of adsorption of ammonia nitrogen on sediment was studied. The results of ammonia nitrogen adsorption dynamics on sediments showed that the maximum adsorption velocity was less than 2 h. The adsorption balance quantity in 5 h accounted for 71% - 98% of the maximum adsorption quantity. The maximum adsorption quantity of ammonia nitrogen was 385.5 mg/kg, which was sediment from a cave in the middle areas of Guancun underground river system. The study of isotherm adsorption indicated adsorption quantity of NH4+ increase followed by incremental balance concentration of NH4+ in the aquatic phase. Adsorption quantity of ammonia nitrogen in sediments has a relative linear relationship with adsorption balance concentrations. Adsorption-desorption balance concentrations were all low, indicating sediments from underground rivers have great adsorption potential. Under the condition of low and high concentrations of ammonia nitrogen in overlying water, Langmuir and Tempkin couldn't simulate or simulate results couldn't reach remarkable level, whilst Linear and Freundlich models could simulate well. Research on different type sediments, sampling times and depths from two underground rivers shows characteristic of ammonia nitrogen adsorption on karst underground river sediments doesn't have good correspondence with the type of sediments. One of the reasons is there is no big difference between sediments in the development of climate, geology, hydrological conditions

  20. 34 CFR 5.81 - Time for initiation of request for review.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... PUBLIC PURSUANT TO PUB. L. 90-23 (Eff. until 7-14-10) Administrative Review § 5.81 Time for initiation of request for review. A person whose request has been denied may initiate a review by filing a request for... 34 Education 1 2010-07-01 2010-07-01 false Time for initiation of request for review. 5.81 Section...

  1. Removal of Reactofix Navy Blue 2 GFN from aqueous solutions using adsorption techniques.

    PubMed

    Gupta, Vinod Kumar; Jain, Rajeev; Varshney, Shaily; Saini, Vipin Kumar

    2007-03-15

    The wheat husk, an agricultural by-product, has been activated and used as an adsorbent for the adsorption of Reactofix Navy Blue 2 GFN from aqueous solution. In this work, adsorption of Reactofix Navy Blue 2 GFN on wheat husk and charcoal has been studied by using batch studies. The equilibrium adsorption level was determined to be a function of the solution pH, adsorbent dosage, dye concentration and contact time. The equilibrium adsorption capacities of wheat husk and charcoal for dye removal were obtained using Freundlich and Langmuir isotherms. Thermodynamic parameters such as the free energies, enthalpies and entropies of adsorption were also evaluated. Adsorption process is considered suitable for removing color, COD from waste water.

  2. Competitive adsorption-desorption reactions of two hazardous heavy metals in contaminated soils.

    PubMed

    Davari, Masoud; Rahnemaie, Rasoul; Homaee, Mehdi

    2015-09-01

    Investigating the interactions of heavy metals is imperative for sustaining environment and human health. Among those, Cd is toxic for organisms at any concentration. While Ni acts as a micronutrient at very low concentration but is hazardous toxic above certain threshold value. In this study, the chemical adsorption and desorption reactions of Ni and Cd in contaminated soils were investigated in both single and binary ion systems. Both Ni and Cd experimental data demonstrated Langmuir type adsorption. In the competitive systems, an antagonistic effect was observed, implying that both ions compete for same type of adsorption sites. Adverse effect of Cd on Ni adsorption was slightly stronger than that of opposite system, consistent with adsorption isotherms in single ion systems. Variation in ionic strength indicated that Ca, a much weaker adsorbate, could also compete with Cd and Ni for adsorption on soil particles. Desorption data indicated that Cd and Ni are adsorbed very tightly such that after four successive desorption steps, less than 0.5 % of initially adsorbed ions released into the soil solution. This implies that Ca, at concentration in equilibrium with calcite mineral, cannot adequately compete with and replace adsorbed Ni and Cd ions. This adsorption behavior was led to considerable hysteresis between adsorption and desorption in both single and binary ion systems. In the binary ion systems, desorption of Cd and Ni was increased by increase in both equilibrium concentration of adsorbed ion and concentration of competitor ion. The overall results obtained in this research indicate that Cd and Ni are strongly adsorbed in calcareous soil and Ca, the major dissolved ion, insignificantly influences metal ions adsorption. Consequently, the contaminated soils by Ni and Cd can simultaneously be remediated by environmentally oriented technologies such as phytoremediation.

  3. Adsorption and photodecomposition of Mo(CO)[sub 6] on Si(111) 7[times]7: An infrared reflection absorption spectroscopy study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Richter, L.J.; Buntin, S.A.; Chu, P.M.

    1994-02-15

    The adsorption and photodecomposition of Mo(CO)[sub 6] adsorbed on Si(111) 7[times]7 surfaces has been studied with Auger electron spectroscopy, temperature programmed desorption, low energy electron diffraction and infrared reflection absorption spectroscopy in a single external reflection configuration. The external-reflection technique is demonstrated to have adequate sensitivity to characterize submonolayer coverages of photogenerated Mo(CO)[sub [ital x

  4. Surface and adsorptive properties of Moringa oleifera bark for removal of V(V) from aqueous solutions.

    PubMed

    Mnisi, Robert Londi; Ndibewu, Peter Papoh

    2017-11-04

    The bark of Moringa oleifera, a cheap and readily available natural biopolymeric resource material, found to significantly reduce coliform load and turbidity in contaminated water is investigated in this paper. Its surface and adsorptive properties are investigated to explore its adsorptive potential in removing V(V) from aqueous solutions. Surface properties were investigated using FTIR, HRSEM/EDS, IC, and BET-N 2 adsorption techniques. Adsorptive properties were investigated by optimizing adsorption parameters such as pH, temperature, initial metal concentration, and adsorbent dosage, using V(V) as an adsorbate. The adsorption-desorption isotherms are typical of type II with a H3 hysteresis loop and is characteristic of a largely macroporous material. Bottle ink pores are observed, which can provide good accessibility of the active sites, even though the internal BET surface area is typically low (1.79 g/m 2 ). Solution pH significantly influences the adsorptive potential of the material. The low surface area negatively impacts on the adsorption capacity, but is compensated for by the exchangeable anions (Cl - , F - , PO 4 3- , NO 3 - , and SO 4 2- ) and cations (Ca 2+ , K + , Mg 2+ , and Al 3+ ) at the surface and the accessibility of the active sites. Adsorption isotherm modeling show that the surface is largely heterogeneous with complex multiple sites and adsorption is not limited to monolayer.

  5. Preparation of chitosan/amine modified diatomite composites and adsorption properties of Hg(II) ions.

    PubMed

    Fu, Yong; Huang, Yue; Hu, Jianshe; Zhang, Zhengjie

    2018-03-01

    A green functional adsorbent (CAD) was prepared by Schiff base reaction of chitosan and amino-modified diatomite. The morphology, structure and adsorption properties of the CAD were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and Brunauer Emmett Teller measurements. The effect of pH value, contact time and temperature on the adsorption of Hg(II) ions for the CAD is discussed in detail. The experimental results showed that the CAD had a large specific surface area and multifunctional groups such as amino, hydroxyl and Schiff base. The optimum adsorption effect was obtained when the pH value, temperature and contact time were 4, 25 °C and 120 min, respectively, and the corresponding maximum adsorption capacity of Hg(II) ions reached 102 mg/g. Moreover, the adsorption behavior of Hg(II) ions for the CAD followed the pseudo-second-order kinetic model and Langmuir model. The negative ΔG 0 and ΔH 0 suggested that the adsorption was a spontaneous exothermic process.

  6. Adsorption enhancement of elemental mercury onto sulphur-functionalized silica gel adsorbents.

    PubMed

    Johari, Khairiraihanna; Saman, Norasikin; Mat, Hanapi

    2014-01-01

    In this study, elemental mercury (EM) adsorbents were synthesized using tetraethyl orthosilicate (TEOS) and 3-mercaptopropyl trimethoxysilane as silica precursors. The synthesized silica gel (SG)-TEOS was further functionalized through impregnation with elemental sulphur and carbon disulphide (CS2). The SG adsorbents were then characterized by using scanning electron microscope, Fourier transform infra-red spectrophotometer, nitrogen adsorption/desorption, and energy-dispersive X-ray diffractometer. The EM adsorption of the SG adsorbents was determined using fabricated fixed-bed adsorber. The EM adsorption results showed that the sulphur-functionalized SG adsorbents had a greater Hgo breakthrough adsorption capacity, confirming that the presence of sulphur in silica matrices can improve Hgo adsorption performance due to their high affinity towards mercury. The highest Hgo adsorption capacity was observed for SG-TEOS(CS2) (82.62 microg/g), which was approximately 2.9 times higher than SG-TEOS (28.47 microg/g). The rate of Hgo adsorption was observed higher for sulphur-impregnated adsorbents, and decreased with the increase in the bed temperatures.

  7. Bovine serum albumin adsorption on titania surfaces and its relation to wettability aspects.

    PubMed

    Valagão Amadeu do Serro, A P; Fernandes, A C; de Jesus Vieira Saramago, B; Norde, W

    1999-09-05

    The adsorption of bovine serum albumin (BSA) from sodium chloride solution and Hanks' balanced salt solution (HBSS) onto TiO2-silicon surfaces is studied by reflectometry in stagnation point flow. The results are compared with those obtained by dynamic contact-angle (DCA) analysis of titanium substrates. The adsorption isotherms show that the adsorbed amount of protein always is lower in HBSS, that is, in the presence of calcium and phosphate ions. This may be related to the increase in surface hydrophilicity caused by these ions, as suggested by the authors in previous works. The rate of adsorption also is lower in HBSS solutions. Comparison of the initial adsorption rates with the rate of mass transfer to the surface reveals that in both solvents only a small fraction of the protein that arrives at the surface adsorbs onto it. Electrostatic and/or conformational effects can explain the energy barrier to adsorption. The DCA analysis of high concentration (4 mg/mL) protein solutions shows a strong reduction of the contact-angle hysteresis, both in HBSS and in NaCl solutions, which confirms that the immediate adsorption of the protein to the surface forms a stable, hydrophilic film. Copyright 1999 John Wiley & Sons, Inc.

  8. Fabrication of a novel NiFe2O4/Zn-Al layered double hydroxide intercalated with EDTA composite and its adsorption behavior for Cr(VI) from aqueous solution

    NASA Astrophysics Data System (ADS)

    Deng, Lin; Shi, Zhou; Wang, Li; Zhou, Shiqing

    2017-05-01

    A novel magnetic NiFe2O4/Zn-Al layered double hydroxide intercalated with EDTA composite (NiFe2O4/ZnAl-EDTA LDH) was prepared through modified coprecipitation method and employed for adsorptive removal of Cr(VI) from aqueous solution. The adsorbents were characterized using Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and X-ray photoelectron spectroscopy (XPS). Factors affecting the Cr(VI) adsorption, such as initial solution pH, adsorbent dosage, contact time, initial Cr(VI) concentration, temperature and coexisting ions, were studied systematically. Experiments results show that the magnetic NiFe2O4/ZnAl-EDTA LDH exhibits high adsorption efficiency within a wide pH range of 3.0-7.0 (R>80% at Cr(VI) concentration 50 mg L-1, contact time 360 min, and adsorbent dosage 2 g/L) and quick separation property. The adsorption process is fitted well with the Langmuir isotherm and pseudo-second-order kinetic model. The maximum theoretical adsorption capacity is found to be 77.22 mg g-1 at pH 6.0 and 318 K. The positive ΔH value (2.907 kJ mol-1) and negative ΔG value (-4.722 kJ mol-1) at 298-318 K reveals that the adsorption process is feasible, spontaneous and endothermic. Coexisting anions (PO43-, SO42-, CO32-, HCO3-, Cl-, and NO3-) have no significant effect on Cr(VI) removal. The mechanism study indicates that the adsorption of Cr(VI) onto NiFe2O4/ZnAl-EDTA LDH mainly involves electrostatic attraction and ion exchange interaction. It is interesting to note that a proportion of Cr(VI) adsorbed on the adsorbent surface are reduced to Cr(III) during the adsorption process. Results from this study demonstrate the potential utility of the magnetic NiFe2O4/ZnAl-EDTA LDH that could be developed into a viable technology for efficient removal of Cr(VI) from aqueous solution.

  9. Adsorption of 2,4-Dichlorophenoxyacetic Acid from an Aqueous Solution on Fly Ash.

    PubMed

    Kuśmierek, Krzysztof; Świątkowski, Andrzej

    2016-03-01

    The adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) on fly ash was studied. The effects of adsorbent dose, contact time, pH, ionic strength, and temperature on the adsorption were investigated. Adsorption kinetic data were analyzed using pseudo-first and pseudo-second order models, and results showed that adsorption kinetics were better represented by the pseudo-second order model. Adsorption isotherms of 2,4-D on fly ash were analyzed using the Freundlich and Langmuir models. Thermodynamic parameters (ΔG°, ΔH°, and ΔS°) indicated that the adsorption process was spontaneous and endothermic. The negative values of ΔG° and the positive value of ΔH° indicate the spontaneous nature of 2,4-D adsorption on fly ash, and that the adsorption process was endothermic. Results showed that fly ash is an efficient, low-cost adsorbent for removal of 2,4-D from water.

  10. The effect of carbon surface chemical composition on the adsorption of acetanilide.

    PubMed

    Terzyk, Artur P

    2004-04-01

    The study of acetanilide adsorption-desorption performed at three temperatures (300, 310, and 320 K) and at two pH levels (7.0 and 1.5) on the series of D43/1 carbons (initial and modified with HNO3, fuming H2SO4, and gaseous NH3) is reported. Sorption data are additionally supplemented with the results of thermal analysis and calorimetric and kinetic measurements. It is shown that, generally, acetanilide adsorption at the neutral pH level is reversible (only on the more acidic carbons and at the lowest temperature does hysteresis occur due to the formation of hydrogen bonds with surface OH groups), and it decreases for the chemically modified carbons. In contrast, at the acidic pH level acetanilide adsorption is irreversible. A mechanism of irreversibility is proposed and it is shown that hysteresis is caused by the chemical reaction between the nucleophile (carbon) and the protonized acetanilide molecules. For all studied carbons, at the acidic pH level, adsorption increases and this is caused by the weakly basic character of acetanilide molecule. Adsorption results are described applying adsorbability and Dubinin-Astakhov, quasi-Freundlich and solution analogue of the Toth adsorption isotherm equations. Using the kinetic data, the effective diffusion coefficients and the energy of diffusion are calculated. It is shown that the diffusion is mainly a surface process, and the contribution of the pore diffusion increases with the rise in temperature. By applying different correlations between the parameters obtained from the theoretical description of experimental data and those characterizing the chemical composition of the studied carbons, the role of the latter in the adsorption and kinetics of acetanilide adsorption is determined.

  11. Removal of malachite green from aqueous solutions by electrocoagulation/peanut shell adsorption coupling in a batch system.

    PubMed

    Wang, Xiansheng; Ni, Jiaheng; Pang, Shuo; Li, Ying

    2017-04-01

    A electrocoagulation (EC)/peanut shell (PS) adsorption coupling technique was studied for the removal of malachite green (MG) in our present work. The addition of an appropriate PS dosage (5 g/L) resulted in remarkable increase in the removal efficiency of MG at lower current density and shorter operating time compared with the conventional EC process. The effect of current density, pH of MG solution, dosage of PS and initial concentration of MG were also investigated. The maximum removal efficiency of MG was 98% under optimum conditions in 5 min. And it was 23% higher than that in EC process. Furthermore, the unit energy demand (UED) and the unit electrode material demand (UEMD) were calculated and discussed. The results demonstrated that the EC/PS adsorption coupling method achieved a reduction of 94% UED and UEMD compared with EC process.

  12. A comparative study for adsorption of lysozyme from aqueous samples onto Fe3O4 magnetic nanoparticles using different ionic liquids as modifier.

    PubMed

    Kamran, Sedigheh; Absalan, Ghodratollah; Asadi, Mozaffar

    2015-12-01

    In this paper, nanoparticles of Fe3O4 as well as their modified forms with different ionic liquids (IL-Fe3O4) were prepared and used for adsorption of lysozyme. The mean size and the surface morphology of the nanoparticles were characterized by TEM, XRD and FTIR techniques. Adsorption studies of lysozyme were performed under different experimental conditions in batch system on different modified magnetic nanoparticles such as, lysozyme concentration, pH of the solution, and contact time. Experimental results were obtained under the optimum operational conditions of pH 9.0 and a contact time of 10 min when initial protein concentrations of 0.05-2.0 mg mL(-1) were used. The isotherm evaluations revealed that the Langmuir model attained better fits to the equilibrium data than the Freundlich model. The maximum obtained adsorption capacities were 370.4, 400.0 500.0 and 526.3 mg of lysozyme for adsorption onto Fe3O4 and modified magnetic nanoparticles by [C4MIM][Br], [C6MIM][Br] and [C8MIM][Br] per gram of adsorbent, respectively. The Langmuir adsorption constants were 0.004, 0.019, 0.024 and 0.012 L mg(-1) for adsorptions of lysozyme onto Fe3O4 and modified magnetic nanoparticles by [C4MIM][Br], [C6MIM][Br] and [C8MIM][Br], respectively. The adsorption capacity of lysozyme was found to be dependent on its chemical structure, pH of the solution, temperature and type of ionic liquid as modifier. The applicability of two kinetic models including pseudo-first order and pseudo-second order model was estimated. Furthermore, the thermodynamic parameters were calculated. Protein could desorb from IL-Fe3O4 nanoparticles by using NaCl solution at pH 9.5 and was reused.

  13. Gas chemical adsorption characterization of lanthanide hexafluoroacetylacetonates

    DOE PAGES

    Stratz, S. Adam; Jones, Steven J.; Mullen, Austin D.; ...

    2017-03-21

    Newly-established adsorption enthalpy and entropy values of 12 lanthanide hexafluoroacetylacetonates, denoted Ln[hfac] 4, along with the experimental and theoretical methodology used to obtain these values, are presented for the first time. The results of this work can be used in conjunction with theoretical modeling techniques to optimize a large-scale gas-phase separation experiment using isothermal chromatography. The results to date indicate average adsorption enthalpy and entropy values of the 12 Ln[hfac] 4 complexes ranging from -33 to -139 kJ/mol K and -299 to -557 J/mol, respectively.

  14. Temperature and pH influence adsorption of cellobiohydrolase onto lignin by changing the protein properties.

    PubMed

    Lu, Xianqin; Wang, Can; Li, Xuezhi; Zhao, Jian

    2017-12-01

    Non-productive adsorption of cellulase onto lignin restricted the movement of cellulase and also hindered the cellulase recycling in bioconversion of lignocellulose. In this study, effect of temperature and pH on adsorption and desorption of cellobiohydrolase (CBH) on lignin and its possible mechanism were discussed. It found that pH value and temperature influenced the adsorption and desorption behaviors of CBH on lignin. Different thermodynamic models suggested that the action between lignin and CBH was physical action. More CBH was adsorbed onto lignin, but lower initial adsorption velocity was detected at 50°C comparing with 4°C. Elevating pH value could improve desorption of cellulase from lignin. The changes of hydrophobicity and electric potential on protein surface may partially explain the impact of environmental conditions on the adsorption and desorption behaviors of CBH on lignin, and comparing to electrical interaction, the hydrophobicity may be the dominating factor influencing the behaviors. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Biodesulfurization of gas oil using inorganic supports biomodified with metabolically active cells immobilized by adsorption.

    PubMed

    Dinamarca, M Alejandro; Ibacache-Quiroga, C; Baeza, P; Galvez, S; Villarroel, M; Olivero, P; Ojeda, J

    2010-04-01

    The immobilization of Pseudomonas stutzeri using adsorption on different inorganic supports was studied in relation to the number of adsorbed cells, metabolic activity and biodesulfurization (BDS). The electrophoretic migration (EM) measurements and Tetrazolioum (TTC) method were used to evaluate adsorption and metabolic activity. Results indicate that maximal immobilization was obtained with an initial load of 14 x 10(8) cells mL(-1) for Al and Sep, whereas Ti requires 20 x 10(8) cells mL(-1). The highest interaction was observed in the P. stutzeri/Si and P. stutzeri/Sep biocatalysts. The IEP values and metabolic activities indicate that P. stutzeri change the surface of supports and maintains metabolic activity. A direct relation between BDS activity and the adsorption capacity of the bacterial cells was observed at the adsorption/desorption equilibrium level. The biomodification of inorganic supports by the adsorption process increases the bioavailability of sulphur substrates for bacterial cells, improving BDS activity. Copyright 2009 Elsevier Ltd. All rights reserved.

  16. Adsorption equilibrium of organic vapors on single-walled carbon nanotubes

    USGS Publications Warehouse

    Agnihotri, S.; Rood, M.J.; Rostam-Abadi, M.

    2005-01-01

    Gravimetric techniques were employed to determine the adsorption capacities of commercially available purified electric arc and HiPco single-walled carbon nanotubes (SWNTs) for organic compounds (toluene, methyl ethyl ketone (MEK), hexane and cyclohexane) at relative pressures, p/p0, ranging from 1 ?? 10-4 to 0.95 and at isothermal conditions of 25, 37 and 50 ??C. The isotherms displayed both type I and type II characteristics. Adsorption isotherm modeling showed that SWNTs are heterogeneous adsorbents, and the Freundlich equation best describes the interaction between organic molecules and SWNTs. The heats of adsorption were 1-4 times the heats of vaporization, which is typical for physical adsorption of organic vapors on porous carbons. ?? 2005 Elsevier Ltd. All rights reserved.

  17. Adsorption behavior of bisphenol A on CTAB-modified graphite

    NASA Astrophysics Data System (ADS)

    Wang, Li-Cong; Ni, Xin-jiong; Cao, Yu-Hua; Cao, Guang-qun

    2018-01-01

    In this work, the adsorption behavior of BPA on CTAB-modified graphite was investigated thoroughly to develop a novel absorbent material. Atomic force microscopy revealed that conical admicelles formed on the surface of graphite. The surface area of graphite decreased significantly from 1.46 to 0.95 m2 g-1, which confirmed the formation of the larger size admicelle instead of the original smaller particle on the surface. CTAB concentration and incubation time affected the progress of admicelle formation on the surface of graphite. Adsolubilization is key in BPA adsorption by CTAB-modified graphite. An extraordinary cation-π electron interaction between CTAB and BPA, revealed by a red-shift in the ultraviolet spectrum, as well as a hydrophobic interaction contribute substantially to BPA adsolubilization. The equilibrium adsorption capacity of the modified graphite for BPA was 125.01 mg g-1. The adsorption kinetic curves of BPA on modified graphite were shown to follow a pseudosecond-order rate. The adsorption process was observed to be both spontaneous and exothermic complied with the Freundlich model.

  18. Enhancement of elemental mercury adsorption by silver supported material.

    PubMed

    Khunphonoi, Rattabal; Khamdahsag, Pummarin; Chiarakorn, Siriluk; Grisdanurak, Nurak; Paerungruang, Adjana; Predapitakkun, Somrudee

    2015-06-01

    Mercury, generally found in natural gas, is extremely hazardous. Although average mercury levels are relatively low, they are further reduced to comply with future mercury regulations, which are stringent in order to avoid releasing to the environment. Herein, vapor mercury adsorption was therefore investigated using two kinds of supports, granular activated carbon (GAC) and titanium dioxide (TiO2). Both supports were impregnated by silver (5 and 15 wt.%), before testing against a commercial adsorbent (sulfur-impregnated activated carbon, SAC). The adsorption isotherm, kinetics, and its thermodynamics of mercury adsorption were reported. The results revealed that Langmuir isotherm provided a better fit to the experimental data. Pseudo second-order was applicable to describe adsorption kinetics. The higher uniform Ag dispersion was a key factor for the higher mercury uptake. TiO2 supported silver adsorbent showed higher mercury adsorption than the commercial one by approximately 2 times. Chemisorption of mercury onto silver active sites was confirmed by an amalgam formation found in the spent adsorbents. Copyright © 2015. Published by Elsevier B.V.

  19. Highly efficient adsorption of cationic dye by biochar produced with Korean cabbage waste.

    PubMed

    Sewu, Divine D; Boakye, Patrick; Woo, Seung H

    2017-01-01

    Biochar was produced from Korean cabbage (KC), rice straw (RS) and wood chip (WC) and the use as alternative adsorbents to activated carbon (AC) in wastewater treatment was investigated. Congo red (CR) and crystal violet (CV) were used as a model anionic and cationic dye, respectively. Initial solution pH had little effect on CR and CV adsorption onto all biochars except for AC on CR. The isotherm models and kinetic data showed that adsorption of CR and CV onto all biochars were dominantly by chemisorption. All biochars had lower adsorption capacity for CR than AC. KC showed higher Langmuir maximum adsorption capacity (1304mg/g) than AC (271.0mg/g), RS (620.3mg/g) and WC (195.6mg/g) for CV. KC may be a good alternative to conventional AC as cheap, superb and industrially viable adsorbent for removal of cationic dyes in wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Designing transition metal surfaces for their adsorption properties and chemical reactivity

    NASA Astrophysics Data System (ADS)

    Montemore, Matthew M.

    adsorbate-surface coupling. A single equation, with only a single adsorbate-dependent fitting parameter as well as a few universal fitting parameters, is developed that can predict the adsorption energy of any radical on any close-packed transition metal surface. The surface electronic properties that are input into this equation can be estimated based on the alloy structure of the surface, improving prospects for high-throughput screening and rational catalyst design. The methods discussed in this thesis are used to design a novel catalyst for ethylene epoxidation, which is experimentally synthesized and tested. Initial tests indicate that this catalyst may have improved selectivity over pure Ag.

  1. Adsorption kinetics of surfactants on activated carbon

    NASA Astrophysics Data System (ADS)

    Arnelli; Aditama, WP; Fikriani, Z.; Astuti, Y.

    2018-04-01

    A study on the adsorption of both cationic and anionic surfactants using activated carbon as well as the investigation of the adsorption isotherms and adsorption kinetics has been conducted. The results showed that the adsorption of sodium lauryl sulfate (SLS) by activated carbon was Langmuir’s adsorption isotherm while its adsorption kinetics showed pseudo-second order with an adsorption rate constant of 2.23 x 103 g mg-1 hour-1. Meanwhile, the adsorption of HDTMA-Br by activated carbon showed that the isotherm adsorption tended to follow Freundlich’s isotherm and was pseudo-second order with an adsorption rate constant of 89.39 g mg-1 hour-1.

  2. Physico-chemical characteristics and protein adsorption potential of hydroxyapatite particles: influence on in vitro biocompatibility of ceramics after sintering.

    PubMed

    Rouahi, M; Champion, E; Gallet, O; Jada, A; Anselme, K

    2006-01-15

    Through the example of two HA ceramics prepared from two HA powders (HAD and HAL), we explored the relation between the physico-chemical qualities of the initial HA powder and the final HA ceramic and their influence on the protein adsorption and cell response to the final HA ceramics. The powders were characterized by XRD, FT-IR, zeta potential, and specific surface area (SSA). Their protein adsorption potential was tested after immersion in culture medium +15% of fetal calf serum. These results were correlated with the protein adsorption potential of the two ceramics (cHAD and cHAL) prepared from the HAD and HAL powders respectively and to the cell attachment after 4, 24 and 72 h on the ceramics. From our results, it appears that a relation can be established between the physico-chemical characteristics of the initial HA powders and the final biological response to the sintered ceramics prepared from these powders. An inverse relation exists between the SSA and the protein adsorption capacity of HA powders and the protein adsorption and cell attachment on HA ceramics. This inverse relation is related to phenomenon occurring during the sintering phase and the formation of inter-granular micro-porosity.

  3. Adsorption of 2,4-dichlorophenoxyacetic acid by mesoporous activated carbon prepared from H3PO4-activated langsat empty fruit bunch.

    PubMed

    Njoku, V O; Islam, Md Azharul; Asif, M; Hameed, B H

    2015-05-01

    The removal of toxic herbicide from wastewater is challenging due to the availability of suitable adsorbents. The Langsat empty fruit bunch is an agricultural waste and was used in this study as a cheap precursor to produce activated carbon for the adsorption of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) at different initial concentrations ranging from 50 to 400 mg/L. The produced Langsat empty fruit bunch activated carbon (LEFBAC) was mesoporous and had high surface area of 1065.65 m(2)/g with different active functional groups. The effect of shaking time, temperature and pH on 2,4-D removal were investigated using the batch technique. The adsorption capacity of 2,4-D by LEFBAC was decreased with increase in pH of solution whereas adsorption capacity increased with temperature. The adsorption data was well described by Langmuir isotherm followed by removal capacity of 261.2 mg/g at 30 °C. The results from this work showed that LEFBAC can be used as outstanding material for anionic herbicide uptake from wastewater. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Treatment of soil eluate containing nitro aromatic compounds by adsorption on activated coke (AC).

    PubMed

    Zhang, Yiping; Jiang, Zhenming; Zhao, Quanlin; Zhang, Zhenzhong; Su, Hongping; Gao, Xuewen; Ye, Zhengfang

    2016-01-01

    Soil washing is a kind of physical method to remove organic matters from contaminated soil. However, its eluate after washing may result in secondary pollution to the environment. In this study, activated coke (AC) was used to remove organic pollutants from contaminated soil eluate. The effect of temperature, initial chemical oxygen demand (COD) and AC dosage on COD removal efficiency was investigated. The results showed that the organic matter can be removed in the eluate because the COD dropped a lot. When the AC dosage was 20 g·L(-1), 88.92% of COD decreased after 480 min of adsorption at 50 °C. The process of adsorption can be described by the Redlich-Peterson isotherm. The adsorption was spontaneous and endothermic. The pseudo-second-order model can be used to describe the adsorption process. After adsorption, the acute toxicity of the eluate was reduced by 76%, and the water qualities were in agreement with Chinese discharge standard GB 14470.1-2002, which means the eluate could be discharged to the environment.

  5. Amino-functionalized mesoporous MCM-41 silica as an efficient adsorbent for water treatment: batch and fixed-bed column adsorption of the nitrate anion

    NASA Astrophysics Data System (ADS)

    Ebrahimi-Gatkash, Mehdi; Younesi, Habibollah; Shahbazi, Afsaneh; Heidari, Ava

    2017-07-01

    In the present study, amino-functionalized Mobil Composite Material No. 41 (MCM-41) was used as an adsorbent to remove nitrate anions from aqueous solutions. Mono-, di- and tri-amino functioned silicas (N-MCM-41, NN-MCM-41 and NNN-MCM-41) were prepared by post-synthesis grafting method. The samples were characterized by means of X-ray powder diffraction, FTIR spectroscopy, thermogravimetric analysis, scanning electron microscopy and nitrogen adsorption-desorption. The effects of pH, initial concentration of anions, and adsorbent loading were examined in batch adsorption system. Results of adsorption experiments showed that the adsorption capacity increased with increasing adsorbent loading and initial anion concentration. It was found that the Langmuir mathematical model indicated better fit to the experimental data than the Freundlich. According to the constants of the Langmuir equation, the maximum adsorption capacity for nitrate anion by N-MCM-41, NN-MCM-41 and NNN-MCM-41 was found to be 31.68, 38.58 and 36.81 mg/g, respectively. The adsorption kinetics were investigated with pseudo-first-order and pseudo-second-order model. Adsorption followed the pseudo-second-order rate kinetics. The coefficients of determination for pseudo-second-order kinetic model are >0.99. For continuous adsorption experiments, NNN-MCM-41 adsorbent was used for the removal of nitrate anion from solutions. Breakthrough curves were investigated at different bed heights, flow rates and initial nitrate anion concentrations. The Thomas and Yan models were utilized to calculate the kinetic parameters and to predict the breakthrough curves of different bed height. Results from this study illustrated the potential utility of these adsorbents for nitrate removal from water solution.

  6. A study of adsorption behavior of human serum albumin and ovalbumin on hydroxyapatite/chitosan composite.

    PubMed

    Xu, Chao; He, Deliang; Zeng, Liping; Luo, Shenglian

    2009-10-15

    In situ adsorption of human serum albumin (HSA) and ovalbumin (OVA) was real-time monitored by piezoelectric quartz crystal impedance (PQCI) technique to fully understand the initial cellular response on hydroxyapatite/chitosan (HAP/CS) composite. The PQCI parameters, such as resonant frequency (f), static capacitance (C(s)), and motional resistance (R(m)) were measured for investigating the kinetic adsorption behaviors of both proteins. The change in frequency shifts (Deltaf) depends on the amount of the adsorbed protein, and the change in motional resistance (DeltaR(m)) results from the microporosity variation of HAP/CS coating. The results show that the amount of the absorbed HSA is much greater than that of OVA on HAP/CS coating because of the unique construction of HSA as well as a flexible protein. Furthermore, Deltaf and DeltaR(m) data were fitted according to the kinetic exponential decay equations. It can be seen that there is only one adsorption process for OVA, but the absorption process for HSA is followed by a rearrangement process, and the former process is faster than the rearrangement process. Subsequently, the composite binding with proteins were demonstrated by the Fourier transform infrared (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).

  7. Adsorbent for p-phenylenediamine adsorption and removal based on graphene oxide functionalized with magnetic cyclodextrin

    NASA Astrophysics Data System (ADS)

    Wang, Dongxue; Liu, Liangliang; Jiang, Xinyu; Yu, Jingang; Chen, Xiaohong; Chen, Xiaoqing

    2015-02-01

    Recently, graphene oxide (GO) based magnetic nanocomposites have been widely used in an adsorption-based process for the removal of organic pollutants from the water system. In this study, magnetic β-cyclodextrin-graphene oxide nanocomposites (MCG) were synthesized according to covalent binding of magnetic β-cyclodextrin nanoparticles onto the GO surface and the as-made nanocomposites were successfully applied as adsorbents for the adsorption and removal of p-phenylenediamines (PPD). The composition and morphology of prepared materials were characterized by Fourier infrared spectrometry (FT-IR), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Effects of pH, temperature, time and reusability on the adsorption of PPD were investigated, as well as the kinetics and isotherms parameters of the adsorbents were determined. The results indicated that the maximum adsorption capacity of MCG was 1102.58 mg/g at 45 °C and pH 8. The adsorption capacity remained at 81% after five cycles. Removal rate could reach 98% after three times of adsorption. The adsorption process with PPD was found that fitted pseudo-second-order kinetics equations and the Langmuir adsorption model. The results showed the MCG had a good adsorption ability to remove organic pollutants in wastewater.

  8. Strong Selective Adsorption of Polymers.

    PubMed

    Ge, Ting; Rubinstein, Michael

    2015-06-09

    A scaling theory is developed for selective adsorption of polymers induced by the strong binding between specific monomers and complementary surface adsorption sites. By "selective" we mean specific attraction between a subset of all monomers, called "sticky", and a subset of surface sites, called "adsorption sites". We demonstrate that, in addition to the expected dependence on the polymer volume fraction ϕ bulk in the bulk solution, selective adsorption strongly depends on the ratio between two characteristic length scales, the root-mean-square distance l between neighboring sticky monomers along the polymer, and the average distance d between neighboring surface adsorption sites. The role of the ratio l / d arises from the fact that a polymer needs to deform to enable the spatial commensurability between its sticky monomers and the surface adsorption sites for selective adsorption. We study strong selective adsorption of both telechelic polymers with two end monomers being sticky and multisticker polymers with many sticky monomers between sticky ends. For telechelic polymers, we identify four adsorption regimes at l / d < 1 that are characterized by the fraction of occupied adsorption sites and whether the dominant conformation of adsorbed chains is a single-end-adsorbed "mushroom" or double-end-adsorbed loop. For l / d > 1, we expect that the adsorption layer at exponentially low ϕ bulk consists of separated unstretched loops, while as ϕ bulk increases the layer crosses over to a brush of extended loops with a second layer of weakly overlapping tails. For multisticker chains, in the limit of exponentially low ϕ bulk , adsorbed polymers are well separated from each other. As l / d increases, the conformation of an individual polymer changes from a single-end-adsorbed "mushroom" to a random walk of loops. For high ϕ bulk , adsorbed polymers at small l / d are mushrooms that cover all the adsorption sites. At sufficiently large l / d , adsorbed multisticker

  9. Electrostatic and dispersion interactions during protein adsorption on topographic nanostructures.

    PubMed

    Elter, Patrick; Lange, Regina; Beck, Ulrich

    2011-07-19

    Recently, biomaterials research has focused on developing functional implant surfaces with well-defined topographic nanostructures in order to influence protein adsorption and cellular behavior. To enhance our understanding of how proteins interact with such surfaces, we analyze the adsorption of lysozyme on an oppositely charged nanostructure using a computer simulation. We present an algorithm that combines simulated Brownian dynamics with numerical field calculation methods to predict the preferred adsorption sites for arbitrarily shaped substrates. Either proteins can be immobilized at their initial adsorption sites or surface diffusion can be considered. Interactions are analyzed on the basis of Derjaguin-Landau-Verway-Overbeek (DLVO) theory, including electrostatic and London dispersion forces, and numerical solutions are derived using the Poisson-Boltzmann and Hamaker equations. Our calculations show that for a grooved nanostructure (i.e., groove and plateau width 8 nm, height 4 nm), proteins first contact the substrate primarily near convex edges because of better geometric accessibility and increased electric field strengths. Subsequently, molecules migrate by surface diffusion into grooves and concave corners, where short-range dispersion interactions are maximized. In equilibrium, this mechanism leads to an increased surface protein concentration in the grooves, demonstrating that the total amount of protein per surface area can be increased if substrates have concave nanostructures.

  10. Studies on adsorption of phenol from wastewater by agricultural waste.

    PubMed

    Girish, C R; Ramachandramurty, V

    2013-07-01

    In this paper, preliminary investigation of various agricultural wastes-Rice mill residue (RM), Wheat mill reside (WM), Dall mill residue (DM) and the Banana peels (BM) was carried out to study their ability to be used as adsorbents for phenol-removal from wastewater. This study reports the feasibility of employing dal mill residue waste (DM) as an adsorbent for removing phenol from wastewater. The performance of DM was compared with the commercially available activated carbon (CAC). Batch mode experiments were conducted with activated DM to study the effects of initial concentration of phenol, pH and the temperature of aqueous solution on adsorption. Equilibrium adsorption isotherms and kinetics were investigated. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models and the isotherm data fitted well to the Freundlich isotherm with monolayer adsorption capacity of 6.189 mg/g. The kinetic data obtained at different concentrations were analyzed using a pseudo-first order and pseudo-second- order equation. The experimental data fitted very well with the pseudo-first-order kinetic model. The FTIR analysis revealed that carboxyl and hydroxyl functional groups were mainly responsible for the sorption of phenol. Finally, the DM was found to be a promising adsorbent for phenol adsorption as compared to activated carbon.

  11. Adsorption behavior of sulfamethazine in an activated sludge process treating swine wastewater.

    PubMed

    Ben, Weiwei; Qiang, Zhimin; Yin, Xiaowei; Qu, Jiuhui; Pan, Xun

    2014-08-01

    Swine wastewater is an important pollution source of antibiotics entering the aquatic environment. In this work, the adsorption behavior of sulfamethazine (SMN), a commonly-used sulfonamide antibiotic, on activated sludge from a sequencing batch reactor treating swine wastewater was investigated. The results show that the adsorption of SMN on activated sludge was an initially rapid process and reached equilibrium after 6hr. The removal efficiency of SMN from the water phase increased with an increasing concentration of mixed liquor suspended solids, while the adsorbed concentration of SMN decreased. Solution pH influenced both the speciation of SMN and the surface properties of activated sludge, thus significantly impacting the adsorption process. A linear partition model could give a good fit for the equilibrium concentrations of SMN at the test temperatures (i.e., 10, 20 and 30°C). The partition coefficient (Kd) was determined to be 100.5L/kg at 20°C, indicating a quite high adsorption capacity for SMN. Thermodynamic analysis revealed that SMN adsorption on activated sludge was an exothermic process. This study could help to clarify the fate and behavior of sulfonamide antibiotics in the activated sludge process and assess consequent environmental risks arising from sludge disposal as well. Copyright © 2014. Published by Elsevier B.V.

  12. Reversible adsorption of catalase onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogels.

    PubMed

    Aktaş Uygun, Deniz; Uygun, Murat; Akgöl, Sinan; Denizli, Adil

    2015-05-01

    In this presented study, poly(acrylamide-glycidyl methacrylate) [poly(AAm-GMA)] cryogels were synthesized by cryopolymerization technique at sub-zero temperature. Prepared cryogels were then functionalized with iminodiacetic acid (IDA) and chelated with Fe(3+) ions in order produce the metal chelate affinity matrix. Synthesized cryogels were characterized with FTIR, ESEM and EDX analysis, and it was found that the cryogel had sponge like structure with interconnected pores and their pore diameter was about 200 μm. Fe(3+) chelated poly(AAm-GMA)-IDA cryogels were used for the adsorption of catalase and optimum adsorption conditions were determined by varying the medium pH, initial catalase concentration, temperature and ionic strength. Maximum catalase adsorption onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was found to be 12.99 mg/g cryogel at 25 °C, by using pH 5.0 acetate buffer. Adsorbed catalase was removed from the cryogel by using 1.0M of NaCl solution and desorption yield was found to be 96%. Additionally, reusability profile of the Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was also investigated and it was found that, adsorption capacity of the cryogels didn't decrease significantly at the end of the 40 reuses. Catalase activity studies were also tested and it was demonstrated that desorbed catalase retained 70% of its initial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Phenols removal using ozonation-adsorption with granular activated carbon (GAC) in rotating packed bed reactor

    NASA Astrophysics Data System (ADS)

    Karamah, E. F.; Leonita, S.; Bismo, S.

    2018-01-01

    Synthetic wastewater containing phenols was treated using combination method of ozonation-adsorption with GAC (Granular Activated Carbon) in a packed bed rotating reactor. Ozone reacts quickly with phenol and activated carbon increases the oxidation process by producing hydroxyl radicals. Performance parameters evaluated are phenol removal percentage, the quantity of hydroxyl radical formed, changes in pH and ozone utilization, dissolved ozone concentration and ozone concentration in off gas. The performance of the combination method was compared with single ozonation and single adsorption. The influence of GAC dose and initial pH of phenols were evaluated in ozonation-adsorption method. The results show that ozonation-adsorption method generates more OH radicals than a single ozonation. Quantity of OH radical formation increases with increasing pH and quantity of the GAC. The combination method prove better performance in removing phenols. At the same operation condition, ozonation-adsorption method is capable of removing of 78.62% phenols as compared with single ozonation (53.15%) and single adsorption (36.67%). The increasing percentage of phenol removal in ozonation-adsorption method is proportional to the addition of GAC dose, solution pH, and packed bed rotator speed. Maximum percentage of phenol removal is obtained under alkaline conditions (pH 10) and 125 g of GAC

  14. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash

    PubMed Central

    Liu, Minmin; Hou, Li-an; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-01-01

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin–Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics. PMID:23687400

  15. Single and binary adsorption of heavy metal ions from aqueous solutions using sugarcane cellulose-based adsorbent.

    PubMed

    Wang, Futao; Pan, Yuanfeng; Cai, Pingxiong; Guo, Tianxiang; Xiao, Huining

    2017-10-01

    A high efficient and eco-friendly sugarcane cellulose-based adsorbent was prepared in an attempt to remove Pb 2+ , Cu 2+ and Zn 2+ from aqueous solutions. The effects of initial concentration of heavy metal ions and temperature on the adsorption capacity of the bioadsorbent were investigated. The adsorption isotherms showed that the adsorption of Pb 2+ , Cu 2+ and Zn 2+ followed the Langmuir model and the maximum adsorptions were as high as 558.9, 446.2 and 363.3mg·g -1 , respectively, in single component system. The binary component system was better described with the competitive Langmuir isotherm model. The three dimensional sorption surface of binary component system demonstrated that the presence of Pb 2+ decreased the sorption of Cu 2+ , but the adsorption amount of other metal ions was not affected. The result from SEM-EDAX revealed that the adsorption of metal ions on bioadsorbent was mainly driven by coordination, ion exchange and electrostatic association. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Role of adsorption in liquid lubrication

    NASA Technical Reports Server (NTRS)

    Groszek, A. J.

    1973-01-01

    Changes at solid-liquid interfaces caused by adsorption from solution are discussed paying attention to the following aspects: (1) stability of adsorbed films and the structure of metal-additive-film-liquid interface and effect of adsorbate orientation. (2) chemical versus physical adsorption, (3) heat of adsorption, (4) adsorption of additives, (5) activated adsorption, effect of activating adsorbates, (6) displacement phenomena at solid-liquid interfaces, (7) competition of antiwear additives, their solvents, and water, (8) effect of adsorption on the orientation of liquid in the interfacial region, and (9) relation between the chemical nature of solid surfaces and their interaction with liquid lubricants. The relevance of the above adsorption phenomena to lubrication is discussed, referring where possible to specific examples.

  17. Single and competitive adsorption of OMPs by carbon nanotubes - mechanism and fitting models

    NASA Astrophysics Data System (ADS)

    Kamińska, Gabriela; Dudziak, Mariusz; Bohdziewicz, Jolanta; Kudlek, Edyta

    2017-11-01

    The adsorption of three organic micropollutants (diclofenac - DFN, pentachlorophenol - PCP and octylphenol - OP) on two kinds of carbon nanotubes (single walled carbon nanotubes - SWCNT and single walled carbon nanotubes with amine group - SWCNT-NH2) was investigated, in single and bicomponent solution at pH 5. SWCNT-NH2 had three times lower specific surface area than SWCNT. Significant differences were observed in sorption capacity of SWCNT and SWCNT-NH2 for given chemicals. The sorption uptake changes in the following order: OP > PCP > DFN for SWCNT and DFN > PCP > OP for SWCNT-NH2. A few times higher adsorption of OP on SWCNT came from low OP solubility in water in comparison to PCP and DFN. While, higher adsorption of DFN and PCP on SWCNT-NH2 was a result of electrostatic attraction between dissociated form of these chemicals and positively charged SWCNT-NH2 at pH 5. In adsorption from bicomponent solution, significant competition was observed between PCP and DFN due to similar adsorption mechanism on SWCNT-NH2. Opposite tendency was observed for SWCNT, DFN did not greatly affect adsorption of PCP and OP since they were very easily absorbable by sigma-sigma interaction.

  18. Recyclable graphene oxide grafted with poly(N-isopropylacrylamide) and its enhanced selective adsorption for phenols

    NASA Astrophysics Data System (ADS)

    Gong, Zailin; Li, Shujin; Han, Weifang; Wang, Jiaping; Ma, Jun; Zhang, Xiangdong

    2016-01-01

    The graphene oxide (GO) was synthesized with Brodie's method and grafted with poly (N-isopropylacrylamide) (NIPAM) in aqueous solution at ambient temperature. Compared with the initial GO, the PNIPAM graft GO (GO-PNIPAM) has larger surface area, pore volume and self-flocculation effect with rapid response to temperature. Moreover, the GO-PNIPAM also has selective adsorptions with different phenol pollutants because of the different interactions of hydrogen bonds and the molecule structure of the adsorbates. Compared with phenol and bisphenol A, hydroquinone has better adsorption on GO-PNIPAM because of the ample phenolic hydroxyl group and the appropriate molecule structure. The adsorption performance of hydroquinone on GO-PNIPAM is also temperature sensitive because of the thermoresponsive transition of the hydrogen bond. The thermoresponsive adsorption and self-flocculation will make the GO-PNIPAM recyclable in the potential water remediation.

  19. Study of polyethyleneimine- and amidoxime-functionalized hybrid biomass of Spirulina (Arthrospira) platensis for adsorption of uranium (VI) ion.

    PubMed

    Bayramoglu, Gulay; Akbulut, Aydin; Arica, M Yakup

    2015-11-01

    This study investigates the potential application of the polyethyleneimine- (PEI) and amidoxime-modified Spirulina (Arthrospira) platensis biomasses for the removal of uranium ion in batch mode using the native biomass as a control system. The uranium ion adsorption was also characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra, zeta potential analysis, and surface area measurement studies. The effects of pH, biomass amount, contact time, initial uranium ion concentration, and ionic strength were evaluated by using native and modified algal biomass preparations. The uranium ion removal was rapid, with more than 70% of total adsorption taking place in 40 min, and equilibrium was established within 60 min. From the experimental data, it was found that the amount of adsorption uranium ion on the algal preparations decreased in the following series: amidoxime-modified algal biomass > PEI-modified algal biomass > native algal biomass. Maximum adsorption capacities of amidoxime- and PEI-modified, and native algal biomasses were found to be 366.8, 279.5, and 194.6 mg/g, respectively, in batchwise studies. The adsorption rate of U(VI) ion by amidoxime-modified algal biomass was higher than those of the native and PEI-modified counterparts. The adsorption processes on all the algal biomass preparations followed by the Dubinin-Radushkevitch (D-R) and Temkin isotherms and pseudo-second-order kinetic models. The thermodynamic parameters were determined at four different temperatures (i.e., 15, 25, 35, and 45 °C) using the thermodynamics constant of the Temkin isotherm model. The ΔH° and ΔG° values of U(VI) ion adsorption on algal preparations show endothermic heat of adsorption; higher temperatures favor the process. The native and modified algal biomass preparations were regenerated using 10 mM HNO3. These results show that amidoxime-modified algal biomass can be a potential candidate for effective removal of U(VI) ion from

  20. Label-free, real-time interaction and adsorption analysis 1: surface plasmon resonance.

    PubMed

    Fee, Conan J

    2013-01-01

    A key requirement for the development of proteins for use in nanotechnology is an understanding of how individual proteins bind to other molecules as they assemble into larger structures. The introduction of labels to enable the detection of biomolecules brings the inherent risk that the labels themselves will influence the nature of biomolecular interactions. Thus, there is a need for label-free interaction and adsorption analysis. In this and the following chapter, two biosensor techniques are reviewed: surface plasmon resonance (SPR) and the quartz crystal microbalance (QCM). Both allow real-time analysis of biomolecular interactions and both are label-free. The first of these, SPR, is an optical technique that is highly sensitive to the changes in refractive index that occur with protein (or other molecule) accumulation near an illuminated gold surface. Unlike QCM ( Chapter 18 ) SPR is not affected by the water that may be associated with the adsorbed layer nor by conformational changes in the adsorbed species. SPR thus provides unique information about the interaction of a protein with its binding partners.

  1. Overcoming double-step CO2 adsorption and minimizing water co-adsorption in bulky diamine-appended variants of Mg2(dobpdc).

    PubMed

    Milner, Phillip J; Martell, Jeffrey D; Siegelman, Rebecca L; Gygi, David; Weston, Simon C; Long, Jeffrey R

    2018-01-07

    Alkyldiamine-functionalized variants of the metal-organic framework Mg 2 (dobpdc) (dobpdc 4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) are promising for CO 2 capture applications owing to their unique step-shaped CO 2 adsorption profiles resulting from the cooperative formation of ammonium carbamate chains. Primary , secondary (1°,2°) alkylethylenediamine-appended variants are of particular interest because of their low CO 2 step pressures (≤1 mbar at 40 °C), minimal adsorption/desorption hysteresis, and high thermal stability. Herein, we demonstrate that further increasing the size of the alkyl group on the secondary amine affords enhanced stability against diamine volatilization, but also leads to surprising two-step CO 2 adsorption/desorption profiles. This two-step behavior likely results from steric interactions between ammonium carbamate chains induced by the asymmetrical hexagonal pores of Mg 2 (dobpdc) and leads to decreased CO 2 working capacities and increased water co-adsorption under humid conditions. To minimize these unfavorable steric interactions, we targeted diamine-appended variants of the isoreticularly expanded framework Mg 2 (dotpdc) (dotpdc 4- = 4,4''-dioxido-[1,1':4',1''-terphenyl]-3,3''-dicarboxylate), reported here for the first time, and the previously reported isomeric framework Mg-IRMOF-74-II or Mg 2 (pc-dobpdc) (pc-dobpdc 4- = 3,3'-dioxidobiphenyl-4,4'-dicarboxylate, pc = para -carboxylate), which, in contrast to Mg 2 (dobpdc), possesses uniformally hexagonal pores. By minimizing the steric interactions between ammonium carbamate chains, these frameworks enable a single CO 2 adsorption/desorption step in all cases, as well as decreased water co-adsorption and increased stability to diamine loss. Functionalization of Mg 2 (pc-dobpdc) with large diamines such as N -( n -heptyl)ethylenediamine results in optimal adsorption behavior, highlighting the advantage of tuning both the pore shape and the diamine size for the development of

  2. ARSENIC TREATMENT BY ADSORPTIVE TECHNOLOGY

    EPA Science Inventory

    Presentation will discuss the removal of arsenic from drinking water using the adsorptive media treatment process. Fundamental information is provided on the design and operation of adsorptive media technology including the selection of the adsorptive media. The information cites...

  3. Enhanced adsorption of chromium onto activated carbon by microwave-assisted H(3)PO(4) mixed with Fe/Al/Mn activation.

    PubMed

    Sun, Yuanyuan; Yue, Qinyan; Mao, Yanpeng; Gao, Baoyu; Gao, Yuan; Huang, Lihui

    2014-01-30

    FeCl3, AlCl3 and MnCl2 were used as the assisted activation agent in activated carbon preparation by H3PO4 activation using microwave heating method. The physico-chemical properties of activated carbons were investigated by scanning electron microscope (SEM), N2 adsorption/desorption, Boehm's titration, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). To investigate the adsorption performances of chromium onto these newly developed activated carbons, a batch of experiments were performed under different adsorption conditions: solution pH, initial Cr(VI) ion concentration, contact time and co-existing ions. The results suggested that carbon with MnCl2 as assisted activation agent displayed the highest BET surface area (1332m(2)/g) and the highest pore volume (1.060cm(3)/g). FeCl3, AlCl3 and MnCl2 had successfully improved Cr(VI) adsorption and activated carbon with FeCl3 as assisted activation agent exhibited the best uptake capacity. To study the transformation of Cr(VI) in adsorption process, total chromium in the aqueous solution was also recorded. The ratio of the amount of Cr(VI) to Cr(III) on each adsorbent was explained by XPS analysis results. Both the co-existing salts (Na2SO4 and NaNO3) demonstrated promoted effects on Cr(VI) removal by four carbons. The pseudo-second-order model and Freundlich equation displayed a good correlation with adsorption data. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Accelerating Gas Adsorption on 3D Percolating Carbon Nanotubes.

    PubMed

    Li, Hui; Wen, Chenyu; Zhang, Youwei; Wu, Dongping; Zhang, Shi-Li; Qiu, Zhi-Jun

    2016-02-18

    In the field of electronic gas sensing, low-dimensional semiconductors such as single-walled carbon nanotubes (SWCNTs) can offer high detection sensitivity owing to their unprecedentedly large surface-to-volume ratio. The sensitivity and responsivity can further improve by increasing their areal density. Here, an accelerated gas adsorption is demonstrated by exploiting volumetric effects via dispersion of SWCNTs into a percolating three-dimensional (3D) network in a semiconducting polymer. The resultant semiconducting composite film is evaluated as a sensing membrane in field effect transistor (FET) sensors. In order to attain reproducible characteristics of the FET sensors, a pulsed-gate-bias measurement technique is adopted to eliminate current hysteresis and drift of sensing baseline. The rate of gas adsorption follows the Langmuir-type isotherm as a function of gas concentration and scales with film thickness. This rate is up to 5 times higher in the composite than only with an SWCNT network in the transistor channel, which in turn results in a 7-fold shorter time constant of adsorption with the composite. The description of gas adsorption developed in the present work is generic for all semiconductors and the demonstrated composite with 3D percolating SWCNTs dispersed in functional polymer represents a promising new type of material for advanced gas sensors.

  5. Interaction of polyhydroxy fullerenes with ferrihydrite: adsorption and aggregation.

    PubMed

    Liu, Jing; Zhu, Runliang; Xu, Tianyuan; Laipan, Mingwang; Zhu, Yanping; Zhou, Qing; Zhu, Jianxi; He, Hongping

    2018-02-01

    The rapid development of nanoscience and nanotechnology, with thousands types of nanomaterials being produced, will lead to various environmental impacts. Thus, understanding the behaviors and fate of these nanomaterials is essential. This study focused on the interaction between polyhydroxy fullerenes (PHF) and ferrihydrite (Fh), a widespread iron (oxyhydr)oxide nanomineral and geosorbent. Our results showed that PHF were effectively adsorbed by Fh. The adsorption isotherm fitted the D-R model well, with an adsorption capacity of 67.1mg/g. The adsorption mean free energy of 10.72kJ/mol suggested that PHF were chemisorbed on Fh. An increase in the solution pH and a decrease of the Fh surface zeta potential were observed after the adsorption of PHF on Fh; moreover, increasing initial solution pH led to a reduction of adsorption. The Fourier transform infrared spectra detected a red shift of C-O stretching from 1075 to 1062cm -1 and a decrease of Fe-O bending, implying the interaction between PHF oxygenic functional groups and Fh surface hydroxyls. On the other hand, PHF affected the aggregation and reactivity of Fh by changing its surface physicochemical properties. Aggregation of PHF and Fh with individual particle sizes increasing from 2nm to larger than 5nm was measured by atomic force microscopy. The uniform distribution of C and Fe suggested that the aggregates of Fh were possibly bridged by PHF. Our results indicated that the interaction between PHF and Fh could evidently influence the migration of PHF, as well as the aggregation and reactivity of Fh. Copyright © 2017. Published by Elsevier B.V.

  6. Adsorption of VOCs on reduced graphene oxide.

    PubMed

    Yu, Lian; Wang, Long; Xu, Weicheng; Chen, Limin; Fu, Mingli; Wu, Junliang; Ye, Daiqi

    2018-05-01

    A modified Hummer's method was adopted for the synthesis of graphene oxide (GO) and reduced graphene oxide (rGO). It was revealed that the modified method is effective for the production of GO and rGO from graphite. Transmission electron microscopy (TEM) images of GO and rGO showed a sheet-like morphology. Because of the presence of oxygenated functional groups on the carbon surface, the interlayer spacing of the prepared GO was higher than that of rGO. The presence of OH and CO groups in the Fourier transform infrared spectra (FTIR) spectrum and G-mode and 2D-mode in Raman spectra confirmed the synthesis of GO and rGO. rGO (292.6m 2 /g) showed higher surface area than that of GO (236.4m 2 /g). The prepared rGO was used as an adsorbent for benzene and toluene (model pollutants of volatile organic compounds (VOCs)) under dynamic adsorption/desorption conditions. rGO showed higher adsorption capacity and breakthrough times than GO. The adsorption capacity of rGO for benzene and toluene was 276.4 and 304.4mg/g, respectively. Desorption experiments showed that the spent rGO can be successfully regenerated by heating at 150.0°C. Its excellent adsorption/desorption performance for benzene and toluene makes rGO a potential adsorbent for VOC adsorption. Copyright © 2017. Published by Elsevier B.V.

  7. Adsorption and desorption characteristics of endosulfan in two typical agricultural soils in Southwest China.

    PubMed

    Qian, Sheng; Zhu, Heng; Xiong, Bailian; Zheng, Guocan; Zhang, Jinzhong; Xu, Weihong

    2017-04-01

    Endosulfan is an organochlorine pesticide widely used in Southwest China. In this paper, the adsorption and desorption characteristics of endosulfan in two typical agricultural soils (latosol and lateritic red soil) in this area were studied. The results showed that Langmuir isothermal equation could well describe the adsorption thermodynamic characteristics of endosulfan in latosol and lateritic red soil, and the maximum adsorption capacities of α-endosulfan were 0.186 and 0.209 mg/g, while those of β-endosulfan were 0.140 and 0.148 mg/g, respectively. Endosulfan adsorption in the two soils was an exothermic physicochemical process, but dominated by physical process. The adsorption kinetic characteristics of endosulfan in the two soils could be well described by second-order kinetic equation, and the initial rate constants were 0.228 and 0.325 mg/(g min) for α-endosulfan, while those were 0.119 and 0.125 mg/(g min) for β-endosulfan, respectively. The adsorbed endosulfan in the two soils was difficult to be desorbed into the liquid phase, and showed weak desorption hysteresis. These results implied that endosulfan could be firmly adsorbed by the two soils, and their adsorption and desorption abilities may be related to the contents of soil clay and organic matter.

  8. Green preparation of a novel red mud@carbon composite and its application for adsorption of 2,4-dichlorophenoxyacetic acid from aqueous solution.

    PubMed

    Kazak, Omer; Eker, Yasin Ramazan; Akin, Ilker; Bingol, Haluk; Tor, Ali

    2017-10-01

    This study reports the eco-friendly preparation of a novel composite material consisting of red mud and carbon spheres, denoted as red mud@C composite, and its application for the removal of 2,4-dichlorophenoxyacetic acid herbicide (2,4-D) from aqueous solution. The preparation route has a green approach because it follows the low-energy consuming one-step hydrothermal process by using starch as a renewable carbon precursor and red mud as a waste from aluminum production industry. Characterization of the red mud@C composite was performed by FT-IR, TGA, SEM, TEM, BET, XRD, and Raman microscopy analyses. The batch adsorption studies revealed that the red mud@C composite has higher 2,4-D adsorption efficiency than those of the red mud and the naked carbon spheres. The maximum removal at initial pH of 3.0 is explained by considering the pKa of 2,4-D and pH of point of zero charge (pH pzc ) of the composite material. The adsorption equilibrium time was 60 min, which followed the pseudo-second-order kinetic model together with intra-particle diffusion model. The isotherm analysis indicated that Freundlich isotherm model better represented the adsorption data, with isotherm parameters of k [15.849 (mg/g) (mg/L) -1/n ] and n (2.985). The prepared composite is reusable at least 5 cycles of adsorption-desorption with no significant decrease in the adsorption capacity.

  9. Effective adsorption of phenolic compound from aqueous solutions on activated semi coke

    NASA Astrophysics Data System (ADS)

    Gao, Xiaoming; Dai, Yuan; Zhang, Yu; Fu, Feng

    2017-03-01

    Activated Semi coke was prepared by KOH activation and employed as adsorbent to study adsorption function of phenolic compound from aqueous solutions. The adsorption result showed that the adsorption capacity of the activated semi coke for phenolic compound increased with contact time and adsorbent dosage, and slightly affected by temperature. The surface structure property of the activated semi coke was characterized by N2 adsorption, indicating that the activated semi coke was essentially macroporous, and the BET surface area was 347.39 m2 g-1. Scanning electron microscopy indicated that the surface of the activated semi coke had a high developed pore. The adsorption kinetics were investigated according to pseudofirst order, pseudosecond order and intraparticle diffusion, and the kinetics data were fitted by pseudosecond order model, and intraparticle diffusion was not the only rate-controlling step. Adsorption isotherm was studied by Langmuir, Freundlich, Temkin, Redlich-Peterson, Sips and Toth models. The result indicated that adsorption isotherm data could fit well with Langmuir, Redlich-Peterson, Sips and Toth models.

  10. Use of adsorption using granular activated carbon (GAC) for the enhancement of removal of chromium from synthetic wastewater by electrocoagulation.

    PubMed

    Vivek Narayanan, N; Ganesan, Mahesh

    2009-01-15

    The present work deals with removal of hexavalent chromium from synthetic effluents in a batch stirred electrocoagulation cell with iron-aluminium electrode pair coupled with adsorption using granular activated carbon (GAC). Several working parameters such as pH, current density, adsorbent concentration and operating time were studied in an attempt to achieve higher removal capacity. Results obtained with synthetic wastewater revealed that most effective removal capacities of chromium (VI) could be achieved when the initial pH was near 8. The removal of chromium (VI) during electrocoagulation, is due to the combined effect of chemical precipitation, coprecipitation, sweep coagulation and adsorption. In addition, increasing current density in a range of 6.7-26.7mA/cm2 and operating time from 20 to 100min enhanced the treatment rate to reduce metal ion concentration below admissible legal levels. The addition of GAC as adsorbent resulted in remarkable increase in the removal rate of chromium at lower current densities and operating time, than the conventional electrocoagulation process. The method was found to be highly efficient and relatively fast compared to existing conventional techniques.

  11. Adsorption of organic chemicals in soils.

    PubMed Central

    Calvet, R

    1989-01-01

    This paper presents a review on adsorption of organic chemicals on soils sediments and their constituents. The first part of this review deals with adsorption from gas and liquid phases and gives a discussion on the physical meaning of the shape of adsorption isotherms. Results show that no general rules can be proposed to describe univocally the relation between the shape of isotherms and the nature of adsorbate-adsorbent system. Kinetics of adsorption is discussed through the description of various models. Theoretical developments exist both for the thermodynamics and the kinetics of adsorption, but there is a strong need for experimental results. Possible adsorption mechanisms are ion exchange, interaction with metallic cations, hydrogen bonds, charge transfers, and London-van der Waals dispersion forces/hydrophobic effect. However, direct proofs of a given mechanism are rare. Several factors influence adsorption behavior. Electronic structure of adsorbed molecules, properties of adsorbents, and characteristics of the liquid phase are discussed in relation to adsorption. Such properties as water solubility, organic carbon content of adsorbing materials, and the composition of the liquid phase are particularly important. Evaluation of adsorption can be obtained through either laboratory measurements or use of several correlations. Adsorption measurements must be interpreted, taking into account treatment of adsorbent materials, experimental conditions, and secondary phenomena such as degradations. Correlations between adsorption coefficients and water-octanol partition coefficient or water solubility are numerous. They may be useful tools for prediction purposes. Relations with transport, bioavailability, and degradation are described. PMID:2695323

  12. Adsorptive removal of antibiotics from water using magnetic ion exchange resin.

    PubMed

    Wang, Tianyue; Pan, Xun; Ben, Weiwei; Wang, Jianbing; Hou, Pin; Qiang, Zhimin

    2017-02-01

    The occurrence of antibiotics in the environment has recently raised serious concern regarding their potential threat to aquatic ecosystem and human health. In this study, the magnetic ion exchange (MIEX) resin was applied for removing three commonly-used antibiotics, sulfamethoxazole (SMX), tetracycline (TCN) and amoxicillin (AMX) from water. The results of batch experiments show that the maximum adsorption capacities on the MIEX resin for SMX, TCN and AMX were 789.32, 443.18 and 155.15μg/mL at 25°C, respectively, which were 2-7 times that for the powdered activated carbon. The adsorption kinetics of antibiotics on the MIEX resin could be simulated by the pseudo-second-order model (R 2 =0.99), and the adsorption isotherm data were well described by the Langmuir model (R 2 =0.97). Solution pH exhibited a remarkable impact on the adsorption process and the absorbed concentrations of the tested antibiotics were obtained around the neutral pH. The MIEX resin could be easily regenerated by 2mol/L NaCl solution and maintained high adsorption removal for the tested antibiotics after regeneration. Anion exchange mechanism mainly controlled the adsorption of antibiotic and the formation of hydrogen binding between the antibiotic and resin can also result in the increase of adsorption capacity. The high adsorption capacity, fast adsorption rate and prominent reusability make the MIEX resin a potential adsorbent in the application for removing antibiotics from water. Copyright © 2016. Published by Elsevier B.V.

  13. Correlational switching between 3{times}1 and 6{times}1 surface reconstructions on Si(111) with submonolayer Ag adsorption

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kempa, K.; Broido, D.A.; Weitering, H.H.

    Electron correlations are strongly enhanced in low dimensional systems. Taking correlations as the dominant mechanism, we provide and explanation of the recently observed electrostatically enforced structural phase transition (3x1 to 6x1) on a Si(111) surface with sub-monolayer Ag adsorption.

  14. Universal emulsion stabilization from the arrested adsorption of rough particles at liquid-liquid interfaces

    PubMed Central

    Zanini, Michele; Marschelke, Claudia; Anachkov, Svetoslav E.; Marini, Emanuele; Synytska, Alla; Isa, Lucio

    2017-01-01

    Surface heterogeneities, including roughness, significantly affect the adsorption, motion and interactions of particles at fluid interfaces. However, a systematic experimental study, linking surface roughness to particle wettability at a microscopic level, is currently missing. Here we synthesize a library of all-silica microparticles with uniform surface chemistry, but tuneable surface roughness and study their spontaneous adsorption at oil–water interfaces. We demonstrate that surface roughness strongly pins the particles' contact lines and arrests their adsorption in long-lived metastable positions, and we directly measure the roughness-induced interface deformations around isolated particles. Pinning imparts tremendous contact angle hysteresis, which can practically invert the particle wettability for sufficient roughness, irrespective of their chemical nature. As a unique consequence, the same rough particles stabilize both water-in-oil and oil-in-water emulsions depending on the phase they are initially dispersed in. These results both shed light on fundamental phenomena concerning particle adsorption at fluid interfaces and indicate future design rules for particle-based emulsifiers. PMID:28589932

  15. Adsorption behavior comparison of trivalent and hexavalent chromium on biochar derived from municipal sludge.

    PubMed

    Chen, Tan; Zhou, Zeyu; Xu, Sai; Wang, Hongtao; Lu, Wenjing

    2015-08-01

    In this work, static equilibrium experiments were conducted to distinguish the adsorption performance between the two valence states of chromium on biochar derived from municipal sludge. The removal capacity of Cr(VI) is lower than 7mg/g at the initial chromium concentration range of 50-200mg/L, whereas that of Cr(III) higher than 20mg/g. It indicates that Cr(III) is much easier to be stabilized than Cr(VI). No significant changes in the biochar surface functional groups are observed before and after the adsorption equilibrium, demonstrating the poor contribution of organic matter in chromium adsorption. The main mechanism of heavy metal adsorption by biochar involves (1) surface precipitation through pH increase caused by biochar buffer ability, and (2) exchange between cations in solution (Cd(2+)) and in biochar matrix (e.g. Ca(2+) and Mg(2+)). The reduction of Cr(VI) to Cr(III) is necessary to improve removal efficiency of chromium. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Universal emulsion stabilization from the arrested adsorption of rough particles at liquid-liquid interfaces

    NASA Astrophysics Data System (ADS)

    Zanini, Michele; Marschelke, Claudia; Anachkov, Svetoslav E.; Marini, Emanuele; Synytska, Alla; Isa, Lucio

    2017-06-01

    Surface heterogeneities, including roughness, significantly affect the adsorption, motion and interactions of particles at fluid interfaces. However, a systematic experimental study, linking surface roughness to particle wettability at a microscopic level, is currently missing. Here we synthesize a library of all-silica microparticles with uniform surface chemistry, but tuneable surface roughness and study their spontaneous adsorption at oil-water interfaces. We demonstrate that surface roughness strongly pins the particles' contact lines and arrests their adsorption in long-lived metastable positions, and we directly measure the roughness-induced interface deformations around isolated particles. Pinning imparts tremendous contact angle hysteresis, which can practically invert the particle wettability for sufficient roughness, irrespective of their chemical nature. As a unique consequence, the same rough particles stabilize both water-in-oil and oil-in-water emulsions depending on the phase they are initially dispersed in. These results both shed light on fundamental phenomena concerning particle adsorption at fluid interfaces and indicate future design rules for particle-based emulsifiers.

  17. Enhancing adsorption of U(VI) onto EDTA modified L. cylindrica using epichlorohydrin and ethylenediamine as a bridge

    PubMed Central

    Su, Shouzheng; Liu, Qi; Liu, Jingyuan; Zhang, Hongsen; Li, Rumin; Jing, Xiaoyan; Wang, Jun

    2017-01-01

    Benefiting from strong coordination ability and unique vascular structure, EDTA modified L. cylindrica opens up an alternative way for uranium recovery from seawater. However, limitations, such as poor adsorption capacity and slow adsorption rate due to low graft ratio of EDTA via one-step esterification block its practical application. Here, a strategy for increasing the graft ratio is proposed in order to improve the adsorption performance. The strategy initially involves immobilization of epichlorohydrin (EPI) onto L. cylindrica and then ethylenediamine (EDA) is introduced via facile ring-opening reaction. EPI and EDA serve as a bridge between L. cylindrica and EDTA. The graft ratio is promoted (15.01 to 21.44%) contributing to the smaller steric hindrance of EPI and EDA than EDTA and improvement in adsorption performance. In addition, the adsorbent prepared by the new strategy exhibits excellent adsorption properties in simulated seawater. PMID:28272435

  18. Adsorptive Removal of Nitrate from Aqueous Solution Using Nitrogen Doped Activated Carbon.

    PubMed

    Machida, Motoi; Goto, Tatsuru; Amano, Yoshimasa; Iida, Tatsuya

    2016-01-01

    Activated carbon (AC) has been widely applied for adsorptive removal of organic contaminants from aqueous phase, but not for ionic pollutants. In this study, nitrogen doped AC was prepared to increase the adsorption capacity of nitrate from water. AC was oxidized with (NH 4 ) 2 S 2 O 8 solution to maximize oxygen content for the first step, and then NH 3 gas treatment was carried out at 950°C to aim at forming quaternary nitrogen (N-Q) species on AC surface (Ox-9.5AG). Influence of solution pH was examined so as to elucidate the relationship between surface charge and adsorption amounts of nitrate. The results showed that Ox-9.5AG exhibited about twice higher adsorption capacity than non-treatment AC at any initial nitrate concentration and any equilibrium solution pH (pH e ) investigated. The more decrease in pH e value, the more adsorption amount of negatively charged nitrate ion, because the surface charge of AC and Ox-9.5AG could become more positive in acidic solution. The oxidation and consecutive ammonia treatments lead to increase in nitrogen content from 0.35 to 6.4% and decrease in the pH of the point of zero charge (pH pzc ) from 7.1 to 4.0 implying that positively charged N-Q of a Lewis acid was created on the surface of Ox-9.5AG. Based on a Langmuir data analysis, maximum adsorption capacity attained 0.5-0.6 mmol/g of nitrate and adsorption affinity was 3.5-4.0 L/mmol at pH e 2.5 for Ox-9.5AG.

  19. Methylene blue adsorption on graphene oxide/calcium alginate composites.

    PubMed

    Li, Yanhui; Du, Qiuju; Liu, Tonghao; Sun, Jiankun; Wang, Yonghao; Wu, Shaoling; Wang, Zonghua; Xia, Yanzhi; Xia, Linhua

    2013-06-05

    Graphene oxide has been used as an adsorbent in wastewater treatment. However, the dispersibility in aqueous solution and the biotoxicity to human cells of graphene oxide limits its practical application in environmental protection. In this research, a novel environmental friendly adsorbent, calcium alginate immobilized graphene oxide composites was prepared. The effects of pH, contact time, temperature and dosage on the adsorption properties of methylene blue onto calcium alginate immobilized graphene oxide composites were investigated. The equilibrium adsorption data were described by the Langmuir and Freundlich isotherms. The maximum adsorption capacity obtained from Langmuir isotherm equation was 181.81 mg/g. The pseudo-first order, pseudo-second order, and intraparticle diffusion equation were used to evaluate the kinetic data. Thermodynamic analysis of equilibriums indicated that the adsorption reaction of methylene blue onto calcium alginate immobilized graphene oxide composites was exothermic and spontaneous in nature. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Adsorption calorimetry during metal vapor deposition on single crystal surfaces: Increased flux, reduced optical radiation, and real-time flux and reflectivity measurements

    NASA Astrophysics Data System (ADS)

    Sellers, Jason R. V.; James, Trevor E.; Hemmingson, Stephanie L.; Farmer, Jason A.; Campbell, Charles T.

    2013-12-01

    Thin films of metals and other materials are often grown by physical vapor deposition. To understand such processes, it is desirable to measure the adsorption energy of the deposited species as the film grows, especially when grown on single crystal substrates where the structure of the adsorbed species, evolving interface, and thin film are more homogeneous and well-defined in structure. Our group previously described in this journal an adsorption calorimeter capable of such measurements on single-crystal surfaces under the clean conditions of ultrahigh vacuum [J. T. Stuckless, N. A. Frei, and C. T. Campbell, Rev. Sci. Instrum. 69, 2427 (1998)]. Here we describe several improvements to that original design that allow for heat measurements with ˜18-fold smaller standard deviation, greater absolute accuracy in energy calibration, and, most importantly, measurements of the adsorption of lower vapor-pressure materials which would have previously been impossible. These improvements are accomplished by: (1) using an electron beam evaporator instead of a Knudsen cell to generate the metal vapor at the source of the pulsed atomic beam, (2) changing the atomic beam design to decrease the relative amount of optical radiation that accompanies evaporation, (3) adding an off-axis quartz crystal microbalance for real-time measurement of the flux of the atomic beam during calorimetry experiments, and (4) adding capabilities for in situ relative diffuse optical reflectivity determinations (necessary for heat signal calibration). These improvements are not limited to adsorption calorimetry during metal deposition, but also could be applied to better study film growth of other elements and even molecular adsorbates.

  1. Adsorption calorimetry during metal vapor deposition on single crystal surfaces: increased flux, reduced optical radiation, and real-time flux and reflectivity measurements.

    PubMed

    Sellers, Jason R V; James, Trevor E; Hemmingson, Stephanie L; Farmer, Jason A; Campbell, Charles T

    2013-12-01

    Thin films of metals and other materials are often grown by physical vapor deposition. To understand such processes, it is desirable to measure the adsorption energy of the deposited species as the film grows, especially when grown on single crystal substrates where the structure of the adsorbed species, evolving interface, and thin film are more homogeneous and well-defined in structure. Our group previously described in this journal an adsorption calorimeter capable of such measurements on single-crystal surfaces under the clean conditions of ultrahigh vacuum [J. T. Stuckless, N. A. Frei, and C. T. Campbell, Rev. Sci. Instrum. 69, 2427 (1998)]. Here we describe several improvements to that original design that allow for heat measurements with ~18-fold smaller standard deviation, greater absolute accuracy in energy calibration, and, most importantly, measurements of the adsorption of lower vapor-pressure materials which would have previously been impossible. These improvements are accomplished by: (1) using an electron beam evaporator instead of a Knudsen cell to generate the metal vapor at the source of the pulsed atomic beam, (2) changing the atomic beam design to decrease the relative amount of optical radiation that accompanies evaporation, (3) adding an off-axis quartz crystal microbalance for real-time measurement of the flux of the atomic beam during calorimetry experiments, and (4) adding capabilities for in situ relative diffuse optical reflectivity determinations (necessary for heat signal calibration). These improvements are not limited to adsorption calorimetry during metal deposition, but also could be applied to better study film growth of other elements and even molecular adsorbates.

  2. Microgravimetric Analysis Method for Activation-Energy Extraction from Trace-Amount Molecule Adsorption.

    PubMed

    Xu, Pengcheng; Yu, Haitao; Li, Xinxin

    2016-05-03

    Activation-energy (Ea) value for trace-amount adsorption of gas molecules on material is rapidly and inexpensively obtained, for the first time, from a microgravimetric analysis experiment. With the material loaded, a resonant microcantilever is used to record in real time the adsorption process at two temperatures. The kinetic parameter Ea is thereby extracted by solving the Arrhenius equation. As an example, two CO2 capture nanomaterials are examined by the Ea extracting method for evaluation/optimization and, thereby, demonstrating the applicability of the microgravimetric analysis method. The achievement helps to solve the absence in rapid quantitative characterization of sorption kinetics and opens a new route to investigate molecule adsorption processes and materials.

  3. Coverage-dependent adsorption and desorption of oxygen on Pd(100)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dunnen, Angela den; Jacobse, Leon; Wiegman, Sandra

    2016-06-28

    We have studied the adsorption and desorption of O{sub 2} on Pd(100) by supersonic molecular beam techniques and thermal desorption spectroscopy. Adsorption measurements on the bare surface confirm that O{sub 2} initially dissociates for all kinetic energies between 56 and 380 meV and surface temperatures between 100 and 600 K via a direct mechanism. At and below 150 K, continued adsorption leads to a combined O/O{sub 2} overlayer. Dissociation of molecularly bound O{sub 2} during a subsequent temperature ramp leads to unexpected high atomic oxygen coverages, which are also obtained at high incident energy and high surface temperature. At intermediatemore » temperatures and energies, these high final coverages are not obtained. Our results show that kinetic energy of the gas phase reactant and reaction energy dissipated during O{sub 2} dissociation on the cold surface both enable activated nucleation of high-coverage surface structures. We suggest that excitation of local substrate phonons may play a crucial role in oxygen dissociation at any coverage.« less

  4. Removal of lead(II) by adsorption using treated granular activated carbon: batch and column studies.

    PubMed

    Goel, Jyotsna; Kadirvelu, Krishna; Rajagopal, Chitra; Kumar Garg, Vinod

    2005-10-17

    In the present study, a deeper understanding of adsorption behavior of Pb(II) from aqueous systems onto activated carbon and treated activated carbon has been attempted via static and column mode studies under various conditions. It probes mainly two adsorbents that is, activated carbon (AC) and modified activated carbon (AC-S). Characterization of both the adsorbents was one of the key focal areas of the present study. This has shown a clear change or demarcation in the various physical and chemical properties of the modified adsorbent from its precursor activated carbon. Both the adsorbents are subjected to static mode adsorption studies and then after a comparison based on isotherm analysis; more efficient adsorbent is screened for column mode adsorption studies. The lead removal increased for sample of treated carbon. The extent of Pb(II) removal was found to be higher in the treated activated carbon. The aim of carrying out the continuous-flow studies was to assess the effect of various process variables, viz., of bed height, hydraulic loading rate and initial feed concentration on breakthrough time and adsorption capacity. This has helped in ascertaining the practical applicability of the adsorbent. Breakthrough curves were plotted for the adsorption of lead on the adsorbent using continuous-flow column operation by varying different operating parameters like hydraulic loading rate (3.0-10.5 m3/(hm2)), bed height (0.3-0.5 m) and feed concentrations (2.0-6.0 mg/l). At the end, an attempt has also been made to model the data generated from column studies using the empirical relationship based on Bohart-Adams model. This model has provided an objective framework to the subjective interpretation of the adsorption system and the model constant obtained here can be used to achieve the ultimate objective of our study that is, up scaling and designing of adsorption process at the pilot plant scale level. AC-S column regeneration using 0.5 and 1.0M concentration of

  5. Simultaneous ultrasound-assisted ternary adsorption of dyes onto copper-doped zinc sulfide nanoparticles loaded on activated carbon: optimization by response surface methodology.

    PubMed

    Asfaram, Arash; Ghaedi, Mehrorang; Hajati, Shaaker; Goudarzi, Alireza; Bazrafshan, Ali Akbar

    2015-06-15

    The simultaneous and competitive ultrasound-assisted removal of Auramine-O (AO), Erythrosine (Er) and Methylene Blue (MB) from aqueous solutions were rapidly performed onto copper-doped zinc sulfide nanoparticles loaded on activated carbon (ZnS:Cu-NP-AC). ZnS:Cu nanoparticles were studied by FESEM, XRD and TEM. First, the effect of pH was optimized in a one-at-a-time procedure. Then the dependency of dyes removal percentage in their ternary solution on the level and magnitude of variables such as sonication time, initial dyes concentrations and adsorbent dosage was fully investigated and optimized by central composite design (CCD) under response surface methodology (RSM) as well as by regarding desirability function (DF) as a good and general criterion. The good agreement found between experimental and predicted values supports and confirms the suitability of the present model to predict adsorption state. The applied ultrasound strongly enhanced mass transfer process and subsequently performance. Hence, a small amount of the adsorbent (0.04 g) was capable to remove high percentage of dyes, i.e. 100%, 99.6% and 100% for MB, AO and Er, respectively, in very short time (2.5 min). The experimental equilibrium data fitting to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models showed that the Langmuir model applies well for the evaluation and description of the actual behavior of adsorption. The small amount of proposed adsorbent (0.015 g) was applicable for successful removal of dyes (RE>99.0%) in short time (2.5 min) with high adsorption capacity in single component system (123.5 mg g(-1) for MB, 123 mg g(-1) for AO and 84.5 mg g(-1) for Er). Kinetics evaluation of experiments at various time intervals reveals that adsorption processes can be well predicated and fitted by pseudo-second-order and Elovich models. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Removal of emerging contaminants from the environment by adsorption.

    PubMed

    Sophia A, Carmalin; Lima, Eder C

    2018-04-15

    Emerging contaminants (EC's) are pollutants of growing concern. They are mainly organic compounds such as: pesticides, pharmaceuticals and personal care products, hormones, plasticizers, food additives, wood preservatives, laundry detergents, surfactants, disinfectants, flame retardants, and other organic compounds that were found recently in natural wastewater stream generated by human and industrial activities. A majority of ECs does not have standard regulations and could lead to lethal effects on human and aquatic life even at small concentrations. The conventional primary and secondary water treatment plants do not remove or degrade these toxic pollutants efficiently and hence need cost effective tertiary treatment method. Adsorption is a promising method worldwide for EC removal since it is low initial cost for implementation, highly-efficient and has simple operating design. Research has shown that the application of different adsorbents such as, activated carbons(ACs), modified biochars (BCs), nanoadsorbents (carbon nanotubes and graphene), composite adsorbents, and other are being used for EC's removal from water and wastewater. The current review intends to investigate adsorption process as an efficient method for the treatment of ECs. The mechanism of adsorption has also been discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Mesoporous-activated carbon prepared from chitosan flakes via single-step sodium hydroxide activation for the adsorption of methylene blue.

    PubMed

    Marrakchi, F; Ahmed, M J; Khanday, W A; Asif, M; Hameed, B H

    2017-05-01

    In this work, mesoporous-activated carbon (CSAC) was prepared from chitosan flakes (CS) via single-step sodium hydroxide activation for the adsorption of methylene blue (MB). CSAC was prepared using different impregnation ratios of NaOH:CS (1:1, 2:1, 3:1, and 4:1) at 800°C for 90min. The adsorption performance of CSAC was evaluated for MB at different adsorption variables, such MB initial concentrations (25-400mg/L), solution pH (3-11), and temperature (30-50°C). The adsorption isotherm data of CSAC-MB were well fitted to Langmuir model with a maximum adsorption capacity 143.53mg/g at 50°C. Best representation of kinetic data was obtained by the pseudo-second order model. CSAC exhibited excellent adsorption uptake for MB and can potentially be used for other cationic dyes. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Adsorption of aluminum and lead from wastewater by chitosan-tannic acid modified biopolymers: Isotherms, kinetics, thermodynamics and process mechanism.

    PubMed

    Badawi, M A; Negm, N A; Abou Kana, M T H; Hefni, H H; Abdel Moneem, M M

    2017-06-01

    Chitosan was reacted by tannic acid to obtain three modified chitosan biopolymer. Their chemical structures were characterized by FTIR and elemental analysis. The prepared biopolymers were used to adsorb Al(III) and Pb(II) metal ions from industrial wastewater. The factors affecting the adsorption process were biosorbent amount, initial concentration of metal ion and pH of the medium. The adsorption efficiency increased considerably with the increase of the biosorbent amount and pH of the medium. The adsorption process of biosorbent on different metal ions was fitted by Freundlich adsorption model. The adsorption kinetics was followed Pseudo-second-order kinetic model. The adsorption process occurred according to diffusion mechanism which was confirmed by the interparticle diffusion model. The modified biopolymers were efficient biosorbents for removal of Pb(II) and Al(III) metal ions from the medium. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Molybdate adsorption from steel slag eluates by subsoils.

    PubMed

    Matern, K; Rennert, T; Mansfeldt, T

    2013-11-01

    Steel slags are industrial by-products which are generated in large amounts worldwide, e.g. 150-230×10(6) Mg in 2012, and which are partly used for construction. Molybdenum (Mo) can be added during steel processing in order to harden the steel. The objective of this study was to evaluate the adsorption behaviour of molybdate (MoO4(2-)) from slag eluates in subsoils. Molybdate batch adsorption experiments were carried out with eluates obtained from two different kinds of steel slags (i) LD slag (Linz-Donawitz operation, LDS) and (ii) electric arc furnace slag (EAF) to assess the risk that may arise from the contamination of groundwater by the leaching of molybdate. Six different subsoils were chosen in order to provide a wide range of chemical properties (pH 4.0-7.6; dithionite-extractable Fe 0.73-14.7 g kg(-1)). Molybdate adsorption experiments were carried out at the pH of the steel slag eluates (pH 11-12) as well as at pH values adjusted to the soil pH. The data were evaluated with the Freundlich equation. Molybdate adsorption exhibited a maximum near pH 4 for steel slag eluates adjusted to the soil pH, and decreased rapidly with increasing pH until adsorption was virtually zero at pH>11. Adsorption was greater for soils with high amounts of dithionite-extractable Fe oxides. The extent and behaviour of molybdate adsorption from both eluates was similar. After a reaction time of 24h, the pH of the EAF slag eluate was lower than that of the LD steel slag eluate, which was caused by different acid buffer capacities. Some soils were able to decrease the pH of the EAF slag eluates by about 4 pH units, enhancing the adsorption of molybdate. Transport simulations indicated that molybdate discharge is low in acidic soils. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Biogas pre-upgrading by adsorption of trace compounds onto granular activated carbons and an activated carbon fiber-cloth.

    PubMed

    Boulinguiez, B; Le Cloirec, P

    2009-01-01

    The study assesses the adsorption onto activated carbon materials of selected volatile organic compounds -VOCs- (dichloromethane, 2-propanol, toluene, siloxane D4) in a biogas matrix composed of methane and carbon dioxide (55:45 v/v). Three different adsorbents are tested, two of them are granular activated carbon (GAC), and the last is an activated carbon fiber-cloth (ACFC). The adsorption isotherm data are fitted by different models by nonlinear regression. The Langmuir-Freundlich model appears to be the adequate one to describe the adsorption phenomena independently of the VOC considered or the adsorbent. The adsorbents present attractive adsorption capacity of the undesirable compounds in biogas atmosphere though the maximum adsorption capacities for a VOC are quite different from each other. The adsorption kinetics are characterized through three coefficients: the initial adsorption coefficient, the external film mass transfer coefficient and the internal diffusion coefficient of Weber. The ACFC demonstrates advanced kinetic yields compared to the granular activated carbon materials whatever VOC is considered. Therefore, pre-upgrading of biogas produced from wastewater sludge or co-digestion system by adsorption onto activated carbon appears worth investigating. Especially with ACFC material that presents correct adsorption capacities toward VOCs and concrete regeneration process opportunity to realize such process.

  11. Equilibrium and kinetic adsorption study of Basic Yellow 28 and Basic Red 46 by a boron industry waste.

    PubMed

    Olgun, Asim; Atar, Necip

    2009-01-15

    In this study, the adsorption characteristics of Basic Yellow 28 (BY 28) and Basic Red 46 (BR 46) onto boron waste (BW), a waste produced from boron processing plant were investigated. The equilibrium adsorption isotherms and kinetics were investigated. The adsorption equilibrium data were analyzed by using various adsorption isotherm models and the results have shown that adsorption behavior of two dyes could be described reasonably well by a generalized isotherm. Kinetic studies indicated that the kinetics of the adsorption of BY 28 and BR 46 onto BW follows a pseudo-second-order model. The result showed that the BW exhibited high-adsorption capacity for basic dyes and the capacity slightly decreased with increasing temperature. The maximum adsorption capacities of BY 28 and BR 46 are reported at 75.00 and 74.73mgg(-1), respectively. The dye adsorption depended on the initial pH of the solution with maximum uptake occurring at about pH 9 and electrokinetic behavior of BW. Activation energy of 15.23kJ/mol for BY 28 and 18.15kJ/mol for BR 46 were determined confirming the nature of the physisorption onto BW. These results indicate that BW could be employed as low-cost material for the removal of the textile dyes from effluents.

  12. A comparative examination of the adsorption mechanism of an anionic textile dye (RBY 3GL) onto the powdered activated carbon (PAC) using various the isotherm models and kinetics equations with linear and non-linear methods

    NASA Astrophysics Data System (ADS)

    Açıkyıldız, Metin; Gürses, Ahmet; Güneş, Kübra; Yalvaç, Duygu

    2015-11-01

    The present study was designed to compare the linear and non-linear methods used to check the compliance of the experimental data corresponding to the isotherm models (Langmuir, Freundlich, and Redlich-Peterson) and kinetics equations (pseudo-first order and pseudo-second order). In this context, adsorption experiments were carried out to remove an anionic dye, Remazol Brillant Yellow 3GL (RBY), from its aqueous solutions using a commercial activated carbon as a sorbent. The effects of contact time, initial RBY concentration, and temperature onto adsorbed amount were investigated. The amount of dye adsorbed increased with increased adsorption time and the adsorption equilibrium was attained after 240 min. The amount of dye adsorbed enhanced with increased temperature, suggesting that the adsorption process is endothermic. The experimental data was analyzed using the Langmuir, Freundlich, and Redlich-Peterson isotherm equations in order to predict adsorption isotherm. It was determined that the isotherm data were fitted to the Langmuir and Redlich-Peterson isotherms. The adsorption process was also found to follow a pseudo second-order kinetic model. According to the kinetic and isotherm data, it was found that the determination coefficients obtained from linear method were higher than those obtained from non-linear method.

  13. Adsorption performance and mechanism of magnetic reduced graphene oxide in glyphosate contaminated water.

    PubMed

    Li, Yajuan; Zhao, Chuanqi; Wen, Yujuan; Wang, Yuanyuan; Yang, Yuesuo

    2018-05-16

    In this study, the magnetic reduced graphene oxide (RGO/Fe 3 O 4 ), with easy separation and high adsorption performance, was prepared and used to treat glyphosate (GLY) contaminated water. GLY adsorption performance of RGO/Fe 3 O 4 was investigated, and influences of pH, adsorption time, temperature, contaminant concentration, and competing anions were analyzed. Moreover, the adsorption mechanism was discussed in the light of several characterization methods, including scanning electron microscopy (SEM), energy dispersive spectrum (EDS), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the RGO/Fe 3 O 4 presented a significant GLY adsorption capacity and acid condition was beneficial for this adsorption. The pseudo-second-order kinetic model and the Langmuir model correlated satisfactorily to the experimental data, indicating that this process was controlled by chemical adsorption and monolayer adsorption. Thermodynamic studies revealed that the adsorption of glyphosate onto RGO/Fe 3 O 4 was spontaneous, endothermic, and feasible process. High temperatures were beneficial to GLY adsorption. The GLY adsorption mechanism of RGO/Fe 3 O 4 was mainly attributed to hydrogen-bond interaction, electrostatic interaction, and coordination. Therefore, the RGO/Fe 3 O 4 investigated in this research may offer an attractive adsorbent candidate for treatment of glyphosate contaminated water and warrant further study as a mechanism for glyphosate efficient removal.

  14. Adsorption of multi-heavy metals Zn and Cu onto surficial sediments: modeling and adsorption capacity analysis.

    PubMed

    Li, Shanshan; Zhang, Chen; Wang, Meng; Li, Yu

    2014-01-01

    Improved multiple regression adsorption models (IMRAMs) was developed to estimate the adsorption capacity of the components [Fe oxides (Fe), Mn oxides (Mn), organic materials (OMs), residuals] in surficial sediments for multi-heavy metal Zn and Cu. IMRAM is an improved version over MRAM, which introduces a computer program in the model developing process. As MRAM, Zn(Cu) IMRAM, and Cu(Zn) IMRAM again confirmed that there is significant interaction effects that control the adsorption of compounded Zn and Cu, which was neglected by additional adsorption model. The verification experiment shows that the relative deviation of the IMRAMs is less than 13%. It is revealed by the IMRAMs that Mn, which has the greatest adsorption capability for compounded Zn and Cu (54.889 and 161.180 mg/l, respectively), follows by interference adsorption capacity of Fe/Mn (-1.072 and -24.591 mg/l respectively). Zn and Cu influence each other through different mechanisms. When Zn is the adsorbate, compounded Cu mainly affects the adsorption capacities of Fe/Mn and Fe/Mn/OMs; while when Cu is the adsorbate, compounded Zn mainly exerts its effect on Mn, Fe/Mn, and Mn/OMs. It also shows that the compounded Zn or Cu weakened the interference adsorption of Fe/Mn, and meanwhile, strengthened the interference adsorption of Mn/OMs.

  15. Enhanced adsorption of methylene blue by citric acid modification of biochar derived from water hyacinth (Eichornia crassipes).

    PubMed

    Xu, Yan; Liu, Yunguo; Liu, Shaobo; Tan, Xiaofei; Zeng, Guangming; Zeng, Wei; Ding, Yang; Cao, Weicheng; Zheng, Bohong

    2016-12-01

    In this work, a novel potential adsorbent, citric acid (CA)-modified biochar, named as CAWB, was obtained from water hyacinth biomass by slow pyrolysis in a N 2 environment at 300 °C. The CA modification focused on enhancing the contaminants adsorption capacity of biochar pyrolyzed at relatively low temperature. Over 90 % of the total methylene blue (MB) could be removed at the first 60 min by CAWB, and the maximum MB adsorption capacity could reach to 395 mg g -1 . The physicochemical properties of CAWB was examined by FTIR, XPS, SEM, and BET analysis. The results indicated that the additional carboxyl groups were introduced to the surface of CAWB via the esterification reaction with CA, which played a significant role in the adsorption of MB. Batch adsorption studies showed that the initial MB concentration, solution pH, background ionic strength, and temperature could affect the removal efficiency obviously. The adsorption process could be well described by the pseudo-second-order kinetic model and Langmuir isotherm. Thermodynamic analysis revealed that the MB adsorption onto CAWB was an endothermic and spontaneous process. The regeneration study revealed that CAWB still exhibited an excellent regeneration and adsorption performance after multiple cycle adsorptions. The adsorption experiments of actual dye wastewater by CAWB suggested that it had a great potential in environmental application.

  16. Investigating alternative solutions for adsorption-contact drying when burning vegetable wastes

    NASA Astrophysics Data System (ADS)

    Golubkovich, A. V.

    2007-06-01

    Results are presented from investigation of three alternative solutions for adsorption-contact drying: combined (with cooling by means of outdoor air), with afterburning of combustible matters, and with limited adsorption of moisture using solid products of fuel combustion. Mathematical models and simplified expressions for calculating the time taken for the fuel drying to proceed are proposed.

  17. Adsorptive removal of organics from aqueous phase by acid-activated coal fly ash: preparation, adsorption, and Fenton regenerative valorization of "spent" adsorbent.

    PubMed

    Wang, Nannan; Hao, Linlin; Chen, Jiaqing; Zhao, Qiang; Xu, Han

    2018-05-01

    Raw coal fly ash was activated to an adsorbent by sulfuric acid impregnation. The activation condition, the adsorption capacity, and the regenerative valorization of the adsorbent were studied. The results show that the optimal preparation conditions of the adsorbent are [H 2 SO 4 ] = 1 mol L -1 , activation time = 30 min, the ratio of coal fly ash to acid = 1:20 (g:mL), calcination temperature = 100 °C. The adsorption of p-nitrophenol on the adsorbent accords with the pseudo-second-order kinetic equation and the adsorption rate constant is 0.089 g mg -1  min -1 . The adsorption on this adsorbent can be considered enough after 35 min, when the corresponding adsorption capacity is 1.07 mg g -1 (85.6% of p-nitrophenol removal). Compared with raw coal fly ash, the adsorbent has a stable adsorption performance at low pH range (pH = 1-6) and the adsorption of p-nitrophenol is an exothermic process. Ninety minutes is required for the regenerative valorization of saturated adsorbent by Fenton process. The regenerative valorization for this saturated adsorbent can reach 89% under the optimal proposed conditions (30 °C, pH = 3, [H 2 O 2 ] = 5.0 mmol L -1 , [Fe 2+ ] = 5.5 mmol L -1 ). Within 15 experimental runs, the adsorbent has a better and better stability with the increase of experimental runs. Finally, the mechanism of activating coal fly ash is proposed, being verified by the results of the SEM and BET test.

  18. Comparison of H2S adsorption by two hydrogel composite (HBC) derived by Empty Fruit Bunch (EFB) biochar and Coal Fly Ash (CFA)

    NASA Astrophysics Data System (ADS)

    Meri, N. H.; Alias, A. B.; Talib, N.; Rashid, Z. A.; Ghani, W. A. W. A. K.

    2018-03-01

    This study are covered the adsorption performance of two adsorbent Empty Fruit Bunch Hydrogel Biochar Composite (EFB-HBC) and Coal Fly Ash Hydrogel Composite (CFA-HC) on hydrogen sulphide. The EFB biochar were produce by pyrolysed and heated from room temperature to 550˚C at 10˚C/min under the Nitrogen flow. Meanwhile, coal fly ash collected from a power plant located in Selangor, Malaysia. Both of the materials is a waste from different industries and became the precursor to our adsorbents. EFB biochar and coal fly ash has been synthesized to become hydrogel by polymerization process with acrylamide (AAm) as monomer, N,N’-methylene bisacry lamide (MBA) as cross linker and ammonium persulfate (APS) as initiator. In addition, because of the speciality of hydrogel itself, which is has high ability in storing water, the effect of H2O wetness on EFB-HBC and CFA-HC were investigate in adsorption of H2S. EFB-HBC gave a longest breakthrough time and highest adsorption capacity compared with CFA-HC in both condition (dry/wet). The result also indicated that, the increased the bed height, increased the adsorption capacity.

  19. MgO-based adsorbents for CO2 adsorption: Influence of structural and textural properties on the CO2 adsorption performance.

    PubMed

    Elvira, Gutiérrez-Bonilla; Francisco, Granados-Correa; Víctor, Sánchez-Mendieta; Alberto, Morales-Luckie Raúl

    2017-07-01

    A series of MgO-based adsorbents were prepared through solution-combustion synthesis and ball-milling process. The prepared MgO-based powders were characterized using X-ray diffraction, scanning electron microscopy, N 2 physisorption measurements, and employed as potential adsorbents for CO 2 adsorption. The influence of structural and textural properties of these adsorbents over the CO 2 adsorption behaviour was also investigated. The results showed that MgO-based products prepared by solution-combustion and ball-milling processes, were highly porous, fluffy, nanocrystalline structures in nature, which are unique physico-chemical properties that significantly contribute to enhance their CO 2 adsorption. It was found that the MgO synthesized by solution combustion process, using a molar ratio of urea to magnesium nitrate (2:1), and treated by ball-milling during 2.5hr (MgO-BM2.5h), exhibited the maximum CO 2 adsorption capacity of 1.611mmol/g at 25°C and 1atm, mainly via chemisorption. The CO 2 adsorption behaviour on the MgO-based adsorbents was correlated to their improved specific surface area, total pore volume, pore size distribution and crystallinity. The reusability of synthesized MgO-BM2.5h was confirmed by five consecutive CO 2 adsorption-desorption times, without any significant loss of performance, that supports the potential of MgO-based adsorbent. The results confirmed that the special features of MgO prepared by solution-combustion and treated by ball-milling during 2.5hr are favorable to be used as effective MgO-based adsorbent in post-combustion CO 2 capture technologies. Copyright © 2016. Published by Elsevier B.V.

  20. Crystal-face-selective adsorption of Au nanoparticles onto polycrystalline diamond surfaces.

    PubMed

    Kondo, Takeshi; Aoshima, Shinsuke; Hirata, Kousuke; Honda, Kensuke; Einaga, Yasuaki; Fujishima, Akira; Kawai, Takeshi

    2008-07-15

    Crystal-face-selective adsorption of Au nanoparticles (AuNPs) was achieved on polycrystalline boron-doped diamond (BDD) surface via the self-assembly method combined with a UV/ozone treatment. To the best of our knowledge, this is the first report of crystal-face-selective adsorption on an inorganic solid surface. Hydrogen-plasma-treated BDD samples and those followed by UV/ozone treatment for 2 min or longer showed almost no adsorption of AuNP after immersion in the AuNP solution prepared by the citrate reduction method. However, the samples treated by UV/ozone for 10 s showed AuNP adsorption on their (111) facets selectively after the immersion. Moreover, the sample treated with UV/ozone for 40-60 s showed AuNP adsorption on the whole surface. These results indicate that the AuNP adsorption behavior can be controlled by UV/ozone treatment time. This phenomenon was highly reproducible and was applied to a two-step adsorption method, where AuNPs from different batches were adsorbed on the (111) and (100) surface in this order. Our findings may be of great value for the fabrication of advanced nanoparticle-based functional materials via bottom-up approaches with simple macroscale procedures.