Bioavailability of organic and inorganic phosphates adsorbed on short-range ordered aluminum precipitate.

PubMed

Shang, C; Caldwell, D E; Stewart, J W; Tiessen, H; Huang, P M

1996-01-01

A nonreductive community-level study of P availability was conducted using various forms of adsorbed P. Orthophosphate (Pi), inositol hexaphosphate (IHP), and glucose 6-phosphate (G6P) were adsorbed to a short-range ordered Al precipitate. These bound phosphates provided a P source sufficient to support the growth of microbial communities from acidic Brazilian soils (oxisols). Adsorbed IHP, the most abundant form of organic phosphate in most soils, had the lowest bioavailability among the three phosphates studied. Adsorbed G6P and Pi were almost equally available. The amount of adsorbed Pi (1 cmol P kg(-1)) required to support microbial growth was at least 30 times less than that of IHP (30 cmol P kg(-1)). With increased surface coverage, adsorbed IHP became more bioavailable. This availability was attributed to a change in the structure of surface complexes and presumably resulted from the decreased number of high-affinity surface sites remaining at high levels of coverage. It thus appears that the bioavailability of various forms of adsorbed phosphate was determined primarily by the stability of the phosphate-surface complexes that they formed, rather than by the total amount of phosphate adsorbed. IHP, having the potential to form stable multiple-ring complexes, had the highest surface affinity and the lowest bioavailability. Bioaggregates consisting of bacteria and Al precipitate were observed and may be necessary for effective release of adsorbed P. Bacteria in the genera Enterobacter and Pseudomonas were the predominate organisms selected during these P-limited enrichments.

Hydroxyapatite-gelatin nanocomposite as a novel adsorbent for nitrobenzene removal from aqueous solution

NASA Astrophysics Data System (ADS)

Wei, Wei; Sun, Rong; Jin, Zhu; Cui, Jing; Wei, Zhenggui

2014-02-01

A novel adsorbent of hydroxyapatite-gelatin (HAP-GEL) nanocomposite was developed for nitrobenzene removal from aqueous solution. The adsorbent was characterized and its performance in nitrobenzene removal was evaluated. The effects of contact time, adsorbent dosage, temperature, pH, ionic strength, humic acid, and the presence of solvent on nitrobenzene adsorption, as well as the thermodynamic parameters for adsorption equilibrium were also investigated. Results showed that HAP-GEL nanocomposite possessed good adsorption ability to nitrobenzene. The adsorption process was fast, and it reached a steady state after only 1 min. Nitrobenzene removal was increased with an increasing amount of adsorbent dosage but decreased as the temperature and pH increased. Meanwhile the amount of nitrobenzene adsorbed decreased with an increase of ionic strength from 0.01 to 1.0 mol/L and humic acid from 10 to 50 mg/L. The adsorption isotherm studies showed that both Langmuir and Freundlich models could fit the experimental data well, and the maximum adsorption capacity was estimated to be 42.373 mg/g. The thermodynamic parameters suggested that the adsorption of nitrobenzene on HAP-GEL nanocomposite was physisorption, spontaneous and exothermic in nature. Findings of this study demonstrated the potential utility of the HAP-GEL nanocomposite as an effective adsorbent for nitrobenzene removal from aqueous solution.

Complexation of lysozyme with adsorbed PtBS-b-SCPI block polyelectrolyte micelles on silver surface.

PubMed

Papagiannopoulos, Aristeidis; Christoulaki, Anastasia; Spiliopoulos, Nikolaos; Vradis, Alexandros; Toprakcioglu, Chris; Pispas, Stergios

2015-01-20

We present a study of the interaction of the positively charged model protein lysozyme with the negatively charged amphiphilic diblock polyelectrolyte micelles of poly(tert-butylstyrene-b-sodium (sulfamate/carboxylate)isoprene) (PtBS-b-SCPI) on the silver/water interface. The adsorption kinetics are monitored by surface plasmon resonance, and the surface morphology is probed by atomic force microscopy. The micellar adsorption is described by stretched-exponential kinetics, and the micellar layer morphology shows that the micelles do not lose their integrity upon adsorption. The complexation of lysozyme with the adsorbed micellar layers depends on the micelles arrangement and density in the underlying layer, and lysozyme follows the local morphology of the underlying roughness. When the micellar adsorbed amount is small, the layers show low capacity in protein complexation and low resistance in loading. When the micellar adsorbed amount is high, the situation is reversed. The adsorbed layers both with or without added protein are found to be irreversibly adsorbed on the Ag surface.

Catalase-like activity studies of the manganese(II) adsorbed zeolites

NASA Astrophysics Data System (ADS)

ćiçek, Ekrem; Dede, Bülent

2013-12-01

Preparation of manganese(II) adsorbed on zeolite 3A, 4A, 5A. AW-300, ammonium Y zeolite, organophilic, molecular sieve and catalase-like enzyme activity of manganese(II) adsorbed zeolites are reported herein. Firstly zeolites are activated at 873 K for two hours before contact manganese(II) ions. In order to observe amount of adsorption, filtration process applied for the solution. The pure zeolites and manganese(II) adsorbed zeolites were analysed by FT-IR. As a result according to the FT-IR spectra, the incorporation of manganese(II) cation into the zeolite structure causes changes in the spectra. These changes are expected particularly in the pseudolattice bands connected with the presence of alumino and silicooxygen tetrahedral rings in the zeolite structure. Furthermore, the catalytic activities of the Mn(II) adsorbed zeolites for the disproportionation of hydrogen peroxide were investigated in the presence of imidazole. The Mn(II) adsorbed zeolites display efficiency in the disproportion reactions of hydrogen peroxide, producing water and dioxygen in catalase-like activity.

CO adsorption on ion bombarded Ni(111): characterization by photoemission from adsorbed xenon

NASA Astrophysics Data System (ADS)

Fu, Sabrina S.; Malafsky, Geoffrey P.; Hsu, David S. Y.

1993-11-01

The adsorption of CO on Ni(111), ion bombarded with various fluences of 1.0 keV Ar + ions, has been investigated using photoemission from adsorbed xenon (PAX). After ion bombardment of the Ni(111) surface, various amounts of CO were adsorbed, followed by adsorption of xenon at 85 K. Two pressures of xenon were used in examining the 3d {5}/{2} peak of xenon: 5 × 10 -6 and 7 × 10 -10 Torr. PAX data taken at both pressures show that CO selectively adsorbs onto the defect (step) sites created by ion bombardment. In addition, it was found that the amount of CO which could occupy a defect site previously occupied by one Xe atom varied from 10 to 2.5, depending on the ion fluence.

High performance of a unique mesoporous polystyrene-based adsorbent for blood purification

PubMed Central

Chen, Jian; Han, Wenyan; Chen, Jie; Zong, Wenhui; Wang, Weichao; Wang, Yue; Cheng, Guanghui; Li, Chunran; Ou, Lailiang; Yu, Yaoting

2017-01-01

A multi-functional polystyrene based adsorbent (NKU-9) with a unique mesoporous and a high surface area was prepared by suspension polymerization for removal of therapeutic toxins in blood purification. The adsorbent produced had an almost equal amount of mesopore distribution in the range from 2 to 50 nm. The adsorption of serum toxins with different molecular weights were examined by in vitro adsorption assays and compared with some clinical currently used adsorbents such as HA-330, Cytosorb and BL-300 which are produced by China, America and Japan, respectively. Test results indicated that the adsorption rate for pentobarbital by NKU-9 was 81.24% which is nearly as high as HA-330 (81.44%). The latter adsorbent is currently used for acute detoxification treatment in China. To reach adsorption equilibrium, NKU-9 was faster than HA-330, which implies short treatment time. For the removal of middle molecular toxins such as β2-microglobulin (98.88%), NKU-9 performed better adsorptive selectivity than Cytosorb (92.80%). In addition, NKU-9 showed high performance for the removal of albumin-bound toxins (e.g., bilirubin), and its adsorption rate for total bilirubin (80.79%) in plasma was 8.4% higher than that of anion exchange resin BL-300 which is currently used to eliminate bilirubin in clinic. Therefore, our results indicate that the newly developed adsorbent with a wide distribution and almost equal amount of mesopores is a multifunctional adsorbent for high efficient removal of serum toxins with different molecular weights which might be an excellent blood purification adsorbent especially to treat diseases that conventional medical methods are low or not efficient. PMID:28149527

High performance of a unique mesoporous polystyrene-based adsorbent for blood purification.

PubMed

Chen, Jian; Han, Wenyan; Chen, Jie; Zong, Wenhui; Wang, Weichao; Wang, Yue; Cheng, Guanghui; Li, Chunran; Ou, Lailiang; Yu, Yaoting

2017-02-01

A multi-functional polystyrene based adsorbent (NKU-9) with a unique mesoporous and a high surface area was prepared by suspension polymerization for removal of therapeutic toxins in blood purification. The adsorbent produced had an almost equal amount of mesopore distribution in the range from 2 to 50 nm. The adsorption of serum toxins with different molecular weights were examined by in vitro adsorption assays and compared with some clinical currently used adsorbents such as HA-330, Cytosorb and BL-300 which are produced by China, America and Japan, respectively. Test results indicated that the adsorption rate for pentobarbital by NKU-9 was 81.24% which is nearly as high as HA-330 (81.44%). The latter adsorbent is currently used for acute detoxification treatment in China. To reach adsorption equilibrium, NKU-9 was faster than HA-330, which implies short treatment time. For the removal of middle molecular toxins such as β2-microglobulin (98.88%), NKU-9 performed better adsorptive selectivity than Cytosorb (92.80%). In addition, NKU-9 showed high performance for the removal of albumin-bound toxins (e.g., bilirubin), and its adsorption rate for total bilirubin (80.79%) in plasma was 8.4% higher than that of anion exchange resin BL-300 which is currently used to eliminate bilirubin in clinic. Therefore, our results indicate that the newly developed adsorbent with a wide distribution and almost equal amount of mesopores is a multifunctional adsorbent for high efficient removal of serum toxins with different molecular weights which might be an excellent blood purification adsorbent especially to treat diseases that conventional medical methods are low or not efficient.

Factors influencing antibiotics adsorption onto engineered adsorbents.

PubMed

Xia, Mingfang; Li, Aimin; Zhu, Zhaolian; Zhou, Qin; Yang, Weiben

2013-07-01

The study evaluated the adsorption of two antibiotics by four engineered adsorbents (hypercrosslinked resin MN-202, macroporous resin XAD-4, activated carbon F-400, and multi-walled carbon nanotubes (MWCNT)) from aqueous solutions. The dynamic results demonstrated the dominant influence of pore size in adsorption. The adsorption amounts of antibiotics on XAD-4 were attributed to the hydrophobic effect, whereas steric hindrance or micropore-filling played a main role in the adsorption of antibiotics by F-400 because of its high microporosity. Aside from F-400, similar patterns of pH-dependent adsorption were observed, implying the importance of antibiotic molecular forms to the adsorption process for adsorbents. Increasing the ionic concentration with CaC12 produced particular adsorption characteristics on MWCNT at pH 2.0 and F-400 at pH 8.0, which were attributed to the highly available contact surfaces and molecular sieving, respectively. Its hybrid characteristics incorporating a considerable portion of mesopores and micropores made hypercross linked MN-202 a superior antibiotic adsorbent with high adsorption capacity. Furthermore, the adsorption capacity of MWCNT on the basis of surface area was more advantageous than that of the other adsorbents because MWCNT has a much more compact molecular arrangement.

Modeling adsorption: Investigating adsorbate and adsorbent properties

NASA Astrophysics Data System (ADS)

Webster, Charles Edwin

1999-12-01

Surface catalyzed reactions play a major role in current chemical production technology. Currently, 90% of all chemicals are produced by heterogeneously catalyzed reactions. Most of these catalyzed reactions involve adsorption, concentrating the substrate(s) (the adsorbate) on the surface of the solid (the adsorbent). Pore volumes, accessible surface areas, and the thermodynamics of adsorption are essential in the understanding of solid surface characteristics fundamental to catalyst and adsorbent screening and selection. Molecular properties such as molecular volumes and projected molecular areas are needed in order to convert moles adsorbed to surface volumes and areas. Generally, these molecular properties have been estimated from bulk properties, but many assumptions are required. As a result, different literature values are employed for these essential molecular properties. Calculated molar volumes and excluded molecular areas are determined and tabulated for a variety of molecules. Molecular dimensions of molecules are important in the understanding of molecular exclusion as well as size and shape selectivity, diffusion, and adsorbent selection. Molecular dimensions can also be used in the determination of the effective catalytic pore size of a catalyst. Adsorption isotherms, on zeolites, (crystalline mineral oxides) and amorphous solids, can be analyzed with the Multiple Equilibrium Analysis (MEA) description of adsorption. The MEA produces equilibrium constants (Ki), capacities (ni), and thermodynamic parameters (enthalpies, ΔHi, and entropies, ΔSi) of adsorption for each process. Pore volumes and accessible surface areas are calculated from the process capacities. Adsorption isotherms can also be predicted for existing and new adsorbate-adsorbent systems with the MEA. The results show that MEA has the potential of becoming a standard characterization method for microporous solids that will lead to an increased understanding of their behavior in gas

Viscoelastic properties of cationic starch adsorbed on quartz studied by QCM-D.

PubMed

Tammelin, Tekla; Merta, Juha; Johansson, Leena-Sisko; Stenius, Per

2004-12-07

The adsorption and viscoelastic properties of layers of a cationic polyelectrolyte (cationic starch, CS, with 2-hydroxy-3-trimethylammoniumchloride as the substituent) adsorbed from aqueous solutions (pH 7.5, added NaCl 0, 1, 100, and 500 mM) on silica were studied with a quartz crystal microbalance with dissipation (QCM-D). Three different starches were investigated (weight-average molecular weights M(w) approximately 8.7 x 10(5) and 4.5 x 10(5) with degree of substitution DS = 0.75 and M(w) approximately 8.8 x 10(5) with DS = 0.2). At low ionic strength, the adsorbed layers are thin and rigid and the amount adsorbed can be calculated using the Sauerbrey equation. When the ionic strength is increased, significant changes take place in the amount of adsorbed CS and the viscoelasticity of the adsorbed layer. These changes were analyzed assuming that the layer can be described as a Voigt element on a rigid surface in contact with purely viscous solvent. It was found that CS with low charge density forms a thicker and more mobile layer with higher viscosity and elasticity than CS with high charge density. The polymers adsorbed on the silica even when the ionic strength was so high that electrostatic interactions were effectively screened. At this high ionic strength, it was possible to study the effect of molecular weight and molecular weight distribution of the CS on the properties of the adsorbed film. Increasing the molecular weight of CS resulted in a larger hydrodynamic thickness. CS with a narrow molecular weight distribution formed a more compact and rigid layer than broadly distributed CS, presumably due to the better packing of the molecules.

A novel starch-based adsorbent for removing toxic Hg(II) and Pb(II) ions from aqueous solution.

PubMed

Huang, Li; Xiao, Congming; Chen, Bingxia

2011-08-30

A novel effective starch-based adsorbent was prepared through two common reactions, which included the esterification of starch with excess maleic anhydride in the presence of pyridine and the cross-linking reaction of the obtained macromonomer with acrylic acid by using potassium persulphate as initiator. The percentage of carboxylic groups of the macromonomer ranged from 14% to 33.4%. The cross-linking degree of the adsorbent was tailored with the amount of acrylic acid which varied from 10wt% to 80wt%. Both Fourier transform infrared spectra and thermogravimetric analysis results verified the structure of the adsorbent. The maximum gel fraction and swelling ratio of the adsorbent were about 72% and 6.25, respectively, and they were able to be adjusted with the amount of monomers. The weight loss percentage of the adsorbent could reach 96.9% after immersing in the buffer solution that contained α-amylase for 14h. It was found that the adsorption capacities of the adsorbent for lead and mercury ions could be 123.2 and 131.2mg/g, respectively. In addition, the adsorbent was able to remove ca. 51-90% Pb(II) and Hg(II) ions that existed in the decoctions of four medicinal herbals. Copyright © 2011 Elsevier B.V. All rights reserved.

Fundamental adsorption characteristics of carbonaceous adsorbents for 1,2,3,4-tetrachlorobenzene in a model gas of an incineration plant.

PubMed

Inoue, Kenichiro; Kawamoto, Katsuya

2005-08-01

Carbonaceous adsorbents such as activated carbon have been used to reduce the emission of organic pollutants from incineration plants. However, with this method, the amount and type of adsorbent to be used are based only on empirical results, which may lead to overuse of the adsorbents. The fundamental adsorption characteristics of several kinds of activated carbon, activated coke, and carbide wood were examined using 1 ,2,3,4-tetrachlorobenzene as an adsorbate. The removal performance and various equilibrium adsorption characteristics of these adsorbents were analyzed using laboratory-scale adsorption equipment. The equilibrium adsorption amount increased by a factor of 1.9-3.2 at 150 degrees C compared with that at 190 degrees C. The effect of the moisture content on adsorption capacity was relatively small in comparison with that of the temperature. The micropore volume for pore diameters of 2 nm or less was the most important factor governing the adsorption capacity for all adsorbents. Activated carbon showed superior adsorption ability compared to activated coke and carbide wood, although all adsorbents were sufficient for practical use.

Possible pore size effects on the state of tris(8-quinolinato)aluminum(III) (Alq3) adsorbed in mesoporous silicas and their temperature dependence.

PubMed

Tagaya, Motohiro; Ogawa, Makoto

2008-12-07

The states of tris(8-quinolinato)aluminum(III) (Alq3) adsorbed in mesoporous silicas with different pore sizes (2.5, 3.1 and 5.0 nm) were investigated. Alq3 was successfully occluded into the mesoporous silicas from solution and the adsorbed amount of Alq3 per BET surface area was effectively controlled by changing the added amount Alq3 to the solution. The state of Alq3 in the mesopore varied depending on the pore size as well as the adsorbed amount of Alq3 as revealed by variation of the photoluminescence spectra. The luminescence of the adsorbed Alq3 was found to be temperature-dependent, indicating the mobility of the adsorbed Alq3 to temperature variations. The temperature-dependence also depended on the pore size. The guest-guest interactions between Alq3 molecules as well as the host-guest interactions between Alq3 and the mesopore were controlled by the pore size.

Uranium Adsorbent Fibers Prepared by Atom-Transfer Radical Polymerization from Chlorinated Polypropylene and Polyethylene Trunk Fibers

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

Brown, Suree; Chatterjee, Sabornie; Li, Meijun

Seawater contains a large amount of uranium (~4.5 billion tons) which can serve as a limitless supply of an energy source. However, in order to make the recovery of uranium from seawater economically feasible, lower manufacturing and deployment costs are required, and thus, solid adsorbents must have high uranium uptake, reusability, and high selectivity toward uranium. In this study, atom-transfer radical polymerization (ATRP), without the radiation-induced graft polymerization (RIGP), was used for grafting acrylonitrile (AN) and tert-butyl acrylate (tBA) from a new class of trunk fibers, forming adsorbents in a readily deployable form. The new class of trunk fibers wasmore » prepared by the chlorination of PP round fiber, hollow-gear-shaped PP fiber, and hollow-gear-shaped PE fiber. During ATRP, degrees of grafting (d.g.) varied according to the structure of active chlorine sites on trunk fibers and ATRP conditions, and the d.g. as high as 2570% was obtained. Resulting adsorbent fibers were evaluated in U-spiked simulated seawater and the maximum adsorption capacity of 146.6 g U/kg, much higher than that of a standard adsorbent JAEA fiber (75.1 g/kg), was obtained. This new type of trunk fibers can be used for grafting a variety of uranium-interacting ligands, including designed ligands that are highly selective toward uranium.« less

Uranium Adsorbent Fibers Prepared by Atom-Transfer Radical Polymerization from Chlorinated Polypropylene and Polyethylene Trunk Fibers

DOE PAGES

Brown, Suree; Chatterjee, Sabornie; Li, Meijun; ...

2015-12-10

Seawater contains a large amount of uranium (~4.5 billion tons) which can serve as a limitless supply of an energy source. However, in order to make the recovery of uranium from seawater economically feasible, lower manufacturing and deployment costs are required, and thus, solid adsorbents must have high uranium uptake, reusability, and high selectivity toward uranium. In this study, atom-transfer radical polymerization (ATRP), without the radiation-induced graft polymerization (RIGP), was used for grafting acrylonitrile (AN) and tert-butyl acrylate (tBA) from a new class of trunk fibers, forming adsorbents in a readily deployable form. The new class of trunk fibers wasmore » prepared by the chlorination of PP round fiber, hollow-gear-shaped PP fiber, and hollow-gear-shaped PE fiber. During ATRP, degrees of grafting (d.g.) varied according to the structure of active chlorine sites on trunk fibers and ATRP conditions, and the d.g. as high as 2570% was obtained. Resulting adsorbent fibers were evaluated in U-spiked simulated seawater and the maximum adsorption capacity of 146.6 g U/kg, much higher than that of a standard adsorbent JAEA fiber (75.1 g/kg), was obtained. This new type of trunk fibers can be used for grafting a variety of uranium-interacting ligands, including designed ligands that are highly selective toward uranium.« less

Adsorbent capability testing using desorption efficiency method on palm oil fiber

NASA Astrophysics Data System (ADS)

Manap, Nor Rahafza Abdul; Shamsudin, Roslinda

2015-09-01

The palm oil fiber had been used as filler in making thermoplastics, biocomposites and also used as adsorbent in treating waste water. In this study, palm oil fiber was used as adsorbent to treat indoor air pollutants that caused by toluene, ethylbenzene, ortho-, meta-, and para- xylene (o-, m-, p-xylene). Known amount of pollutants, ranges between 1.3 to 28 ppm was spiked into palm oil fiber and left in refrigerator for 24 hours. Then, elution of the pollutants was carried out by carbon disulphide as mobile phase or eluent. The ability of palm oil fiber as adsorbent was determine using desorption efficiency technique by gas chromatography with flame ionization detector (GC/FID). The desorption efficiency percentage given by toluene was in the range of 88.9% to 100%, 91% to 100% for ethylbenzene, 65% to 100% for pm-xylene and 92.9% to 100% for o-xylene. This percentage indicates that palm oil fiber can be used as adsorbent to treat indoor air pollutants.

In Situ Investigation the Photolysis of the PAHs Adsorbed on Mangrove Leaf Surfaces by Synchronous Solid Surface Fluorimetry

PubMed Central

Wang, Ping; Wu, Tun-Hua; Zhang, Yong

2014-01-01

An established synchronous solid surface fluorimetry (S-SSF) was utilized for in situ study the photolysis processes of anthracene (An) and pyrene (Py) adsorbed on the leaf surfaces of Kandelia obovata seedlings (Ko) and Aegiceras corniculata (L.) Blanco seedlings (Ac). Experimental results demonstrated that the photolysis of An and Py adsorbed on the leaf surfaces of two mangrove species under the laboratory conditions, followed first-order kinetics with their photolysis rates in the order of Ac>Ko. In addition, with the same amount of substances, the photolysis rate of An adsorbed on the same mangrove leaf surfaces was much faster than the adsorbed Py. In order to investigate further, the photolysis processes of An and Py in water were also studied for comparison. And the photolysis of An and Py in water also followed first-order kinetics. Moreover, for the same initial amount, the photolysis rate of the PAH in water was faster than that adsorbed on the leaf surfaces of two mangrove species. Therefore, photochemical behaviors of PAHs were dependent not only on their molecular structures but also the physical-chemical properties of the substrates on which they are adsorbed. PMID:24404158

Molecular Adsorber Coating

NASA Technical Reports Server (NTRS)

Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Hedgeland, Randy; Petro, John; Novo-Gradac, Kevin; Wong, Alfred; Triolo, Jack; Miller, Cory

2011-01-01

A document discusses a zeolite-based sprayable molecular adsorber coating that has been developed to alleviate the size and weight issues of current ceramic puck-based technology, while providing a configuration that more projects can use to protect against degradation from outgassed materials within a spacecraft, particularly contamination-sensitive instruments. This coating system demonstrates five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was developed and refined, and a procedure for spray application was developed. Samples were spray-coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate-based coatings. The coating can also function as a thermal- control coating. This adsorber will dramatically reduce the mass and volume restrictions, and is less expensive than the currently used molecular adsorber puck design.

From MDF and PB wastes to adsorbents for the removal of pollutants

NASA Astrophysics Data System (ADS)

Gomes, J. A. F. L.; Azaruja, B. A.; Mourão, P. A. M.

2016-09-01

The production of activated carbons in powder and monolith forms, by physical activation with CO2, with specific surface areas between 804 and 1469 m2 g-1, porous volume between 0.33 and 0.59 cm3 g-1, with basic nature (PZC ∼ 9.6-10.6) was achieved in our lab, from medium density fibreboard (MDF) and particleboard (PB), engineered wood composites wastes. These highly porous adsorbents were applied in kinetic and equilibrium adsorption studies, in batch and dynamic modes, in powder and monolith forms, of specific adsorptives, considered pollutants, namely phenol (P), p-nitrophenol (PNP) and neutral red (NR). In batch the maximum adsorbed amount was 267, 162 and 92 mg g-1, for PNP, P and NR, respectively. The application of different kinetic models (pseudo-first order, pseudo-second order and intraparticle diffusion model) leads to a better knowledge of the adsorption mechanisms of those adsorptives. The results obtained in the kinetic and equilibrium tests show that the combination of the structural features and the surface chemistry nature of the adsorbents, with the adsorptives properties, establish the kinetic performance, the type and amount adsorbed for each system. This work confirms the potential of these types of wastes in the production of activated carbons and its application in adsorption from liquid phase.

Performance evaluation of oxygen adsorbents using negative corona discharge-ion mobility spectrometry.

PubMed

Azadkish, Kamal; Jafari, Mohammad T; Ghaziaskar, Hassan S

2017-02-08

Trace amounts of oxygen was determined using negative corona discharge as an ionization source for ion mobility spectrometry. A point-in-cylinder geometry with novel design was used to establish the corona discharge without interferences of negative ions such as NO X - . The desirable background spectrum shows only electrons peak, providing the instrument capable of trace analysis of oxygen in gaseous samples. The limit of detection and linear dynamic range with high coefficient of determination (r 2  = 0.9997), were obtained for oxygen as 8.5 and 28-14204 ppm, respectively. The relative standard deviations of the method for intraday and interday were obtained 4 and 11%, respectively. The satisfactory results revealed the ability of the negative corona discharge ion mobility spectrometry for investigating the performance of synthesized oxygen adsorbents in nitrogen streams. Two oxygen scavengers of MnO and Cu powder were prepared and the optimum temperature of the reactor containing MnO and Cu powder were obtained as 180 and 230 °C, respectively. Due to higher lifetime of copper powder, it was selected as the oxygen scavenger and some parameters such as: the type of adsorbent support, the size of adsorbent particles, and the amount of copper were studied for preparation of more efficient oxygen adsorbent. Copyright © 2016 Elsevier B.V. All rights reserved.

Desorption of isopropyl alcohol from adsorbent with non-thermal plasma.

PubMed

Shiau, Chen Han; Pan, Kuan Lun; Yu, Sheng Jen; Yan, Shaw Yi; Chang, Moo Been

2017-09-01

Effective desorption of isopropyl alcohol (IPA) from adsorbents with non-thermal plasma is developed. In this system, IPA is effectively adsorbed with activated carbon while dielectric barrier discharge is applied to replace the conventional thermal desorption process to achieve good desorption efficiency, making the treatment equipment smaller in size. Various adsorbents including molecular sieves and activated carbon are evaluated for IPA adsorption capacity. The results indicate that BAC has the highest IPA adsorption capacity (280.31 mg IPA/g) under the operating conditions of room temperature, IPA of 400 ppm, and residence time of 0.283 s among 5 adsorbents tested. For the plasma desorption process, the IPA selectivity of 89% is achieved with BAC as N 2 is used as desorbing gas. In addition, as air or O 2 is used as desorbing gas, the IPA desorption concentration is reduced, because air and O 2 plasmas generate active species to oxidize IPA to form acetone, CO 2 , and even CO. Furthermore, the results of the durability test indicate that the amount of IPA desorbed increases with increasing desorption times and plasma desorption process has a higher energy efficiency if compared with thermal desorption. Overall, this study indicates that non-thermal plasma is a viable process for removing VOCs to regenerate adsorbent.

Rapid detection of trace amounts of surfactants using nanoparticles in fluorometric assays

NASA Astrophysics Data System (ADS)

Härmä, Harri; Laakso, Susana; Pihlasalo, Sari; Hänninen, Pekka; Faure, Bertrand; Rana, Subhasis; Bergström, Lennart

2010-01-01

Rapid microtiter assays that utilize the time-resolved fluorescence resonance energy transfer or quenching of dye-labeled proteins adsorbed onto the surfaces of polystyrene or maghemite nanoparticles have been developed for the detection and quantification of trace amounts of surfactants at concentrations down to 10 nM.Rapid microtiter assays that utilize the time-resolved fluorescence resonance energy transfer or quenching of dye-labeled proteins adsorbed onto the surfaces of polystyrene or maghemite nanoparticles have been developed for the detection and quantification of trace amounts of surfactants at concentrations down to 10 nM. Electronic supplementary information (ESI) available: Experimental details and Fig. S1 and S2. See DOI: 10.1039/b9nr00172g

Selective Gas Capture Ability of Gas-Adsorbent-Incorporated Cellulose Nanofiber Films.

PubMed

Shah, Kinjal J; Imae, Toyoko

2016-05-09

The 2,2,6,6-tetramethylpiperidine-1-oxyl radical-oxidized cellulose nanofibers (TOCNF) were hybridized with cation and anion-exchange organoclays, where poly(amido amine) dendrimers were loaded to enhance the functionality of gas adsorption, since dendrimers have the high adsorbability and the enough selectivity on the gas adsorption. The thin films were prepared from the organoclay-TOCNF hybrids and supplied to the gas adsorption. The adsorption of CO2 and NH3 gases increased with an increasing amount of organoclays in TOCNF films, but the behavior of the increase depended on gases, clays, and dendrimers. The hydrotalcite organoclay-TOCNF films displayed the highest adsorption of both gases, but the desorption of CO2 gas from hydrotalcite organoclay-TOCNF films was drastically high in comparison with the other systems. While the CO2 gas is adsorbed and remained on cationic dendrimer sites in cation-exchange organoclay-TOCNF films, the CO2 gas is adsorbed on cationic clay sites in anion exchange organoclay-TOCNF films, and it is easily desorbed from the films. The NH3 adsorption is inversive to the CO2 adsorption. Then the CO2 molecules adsorbed on the cationic dendrimers and the NH3 molecules adsorbed on the anionic dendrimers are preferably captured in these adsorbents. The present research incorporated dendrimers will be contributing to the development of gas-specialized adsorbents, which are selectively storable only in particular gases.

The uranium from seawater program at PNNL: Overview of marine testing, adsorbent characterization, adsorbent durability, adsorbent toxicity, and deployment studies

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

Gill, Gary A.; Kuo, Li -Jung; Janke, Christopher James

The Pacific Northwest National Laboratory's (PNNL) Marine Science Laboratory (MSL) located along the coast of Washington State is evaluating the performance of uranium adsorption materials being developed for seawater extraction under realistic marine conditions with natural seawater. Two types of exposure systems were employed in this program: flow-through columns for testing of fixed beds of individual fibers and pellets and a recirculating water flume for testing of braided adsorbent material. Testing consists of measurements of the adsorption of uranium and other elements from seawater as a function of time, typically 42 to 56 day exposures, to determine the adsorbent capacitymore » and adsorption rate (kinetics). Analysis of uranium and other trace elements collected by the adsorbents was conducted following strong acid digestion of the adsorbent with 50% aqua regia using either Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The ORNL 38H adsorbent had a 56 day adsorption capacity of 3.30 ± 0.68 g U/ kg adsorbent (normalized to a salinity of 35 psu), a saturation adsorption capacity of 4.89 ± 0.83 g U/kg of adsorbent material (normalized to a salinity of 35 psu) and a half-saturation time of 28 10 days. The AF1 adsorbent material had a 56 day adsorption capacity of 3.9 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu), a saturation capacity of 5.4 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu) and a half saturation time of 23 2 days. The ORNL amidoxime-based adsorbent materials are not specific for uranium, but also adsorb other elements from seawater. The major doubly charged cations in seawater (Ca and Mg) account for a majority of the cations adsorbed (61% by mass and 74% by molar percent). For the ORNL AF1 adsorbent material, U is the 4th most abundant element adsorbed by mass and 7th most abundant by molar percentage. Marine testing

The uranium from seawater program at PNNL: Overview of marine testing, adsorbent characterization, adsorbent durability, adsorbent toxicity, and deployment studies

DOE PAGES

Gill, Gary A.; Kuo, Li -Jung; Janke, Christopher James; ...

2016-02-07

The Pacific Northwest National Laboratory's (PNNL) Marine Science Laboratory (MSL) located along the coast of Washington State is evaluating the performance of uranium adsorption materials being developed for seawater extraction under realistic marine conditions with natural seawater. Two types of exposure systems were employed in this program: flow-through columns for testing of fixed beds of individual fibers and pellets and a recirculating water flume for testing of braided adsorbent material. Testing consists of measurements of the adsorption of uranium and other elements from seawater as a function of time, typically 42 to 56 day exposures, to determine the adsorbent capacitymore » and adsorption rate (kinetics). Analysis of uranium and other trace elements collected by the adsorbents was conducted following strong acid digestion of the adsorbent with 50% aqua regia using either Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The ORNL 38H adsorbent had a 56 day adsorption capacity of 3.30 ± 0.68 g U/ kg adsorbent (normalized to a salinity of 35 psu), a saturation adsorption capacity of 4.89 ± 0.83 g U/kg of adsorbent material (normalized to a salinity of 35 psu) and a half-saturation time of 28 10 days. The AF1 adsorbent material had a 56 day adsorption capacity of 3.9 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu), a saturation capacity of 5.4 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu) and a half saturation time of 23 2 days. The ORNL amidoxime-based adsorbent materials are not specific for uranium, but also adsorb other elements from seawater. The major doubly charged cations in seawater (Ca and Mg) account for a majority of the cations adsorbed (61% by mass and 74% by molar percent). For the ORNL AF1 adsorbent material, U is the 4th most abundant element adsorbed by mass and 7th most abundant by molar percentage. Marine testing

Evaluation of pharmaceuticals removal by sewage sludge-derived adsorbents with rapid small-scale column tests

NASA Astrophysics Data System (ADS)

Zhang, P.; Ding, R.; Wallace, R.; Bandosz, T.

2015-12-01

New composite adsorbents were developed by pyrolyzing sewage sludge and fish waste (75:25 or 90:10 dry mass ratio) at 650 oC and 950 oC. Batch adsorption experiments demonstrated that the composite adsorbents were able to adsorb a wide range of organic contaminants (volatile organic compounds, pharmaceuticals and endocrine disrupting compounds (EDCs), and nitrosamine disinfection byproducts) with high capacities. Here we further examine the performance of the adsorbents for the simultaneous removal of 8 pharmaceuticals and EDCs with rapid small-scale column tests (RSSCT). Results show that the order of breakthrough in RSSCT is in general consistent with the affinity determined via batch tests. As expected, the maximum amount of adsorption for each compound obtained from RSSCT is identical to or less than that obtained from batch tests (with only one exception), due to adsorption kinetics. However, despite the very different input concentration (1 mg/L vs. 100 mg/L) and contact time (2 min empty bed contact time vs. 16 hour equilibrium time) used in RSSCT and batch tests, the maximum amount of pharmaceuticals and EDCs adsorbed under RSSCT is still about one half of that under equilibrium batch tests, validating the approach of using batch tests with much higher input concentrations to determine adsorption capacities. Results of a pilot-scale column test in a drinking water treatment plant for pharmaceuticals removal will also be presented.

New Fiber Materials with Sorption Capacity at 5.0 g-U/kg Adsorbent under Marine Testing Conditions

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

Saito, Tomonori; Brown, S.; Das, Sadananda

The Fuel Resources program of the Fuel Cycle Research and Development program of the Office of Nuclear Energy (NE) has focused on assuring that nuclear fuel resources are available in the United States for a long term. An immense source of uranium is seawater, which contains an estimated amount of 4.5 billion tonnes of dissolved uranium. Extraction of the uranium resource in seawater can provide a price cap and ensure centuries of uranium supply for future nuclear energy production. NE initiated a multidisciplinary program with participants from national laboratories, universities, and research institutes to enable technical breakthroughs related to uraniummore » recovery from seawater. The goal is to develop advanced adsorbents to make the seawater uranium recovery technology a cost competitive, viable technology. Under this program, Oak Ridge National Laboratory (ORNL) has developed several novel adsorbents, which enhanced the uranium capacity 4-5 times from the state-of-the art Japanese adsorbents. Uranium exists uniformly at a concentration of ~3.3 ppb in seawater. Because of the vast volume of the oceans, the total estimated amount of uranium in seawater is approximately 1000 times larger than its amount in terrestrial resources. However, due to the low concentration, a significant challenge remains for making the extraction of uranium from seawater a commercially viable alternative technology. The biggest challenge for this technology to overcome to efficiently reduce the extraction cost is to develop adsorbents with increased uranium adsorption capacity. Two major approaches were investigated for synthesizing novel adsorbents with enhanced uranium adsorption capacity. One method utilized conventional radiation induced graft polymerization (RIGP) to synthesize adsorbents on high-surface area trunk fibers and the other method utilized a chemical grafting technique, atom-transfer radical polymerization (ATRP). Both approaches have shown promising uranium

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.

Establishment of hepatitis A vaccine (inactivated, non-adsorbed) BRP batches 2 and 3.

PubMed

Morgeaux, S; Manniam, I; Variot, P; Buchheit, K H; Daas, A; Wierer, M; Costanzo, A

2015-01-01

The current hepatitis A vaccine (HAV), inactivated, non-adsorbed, European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP) is used for the in vitro potency assay of HAV as prescribed by the Ph. Eur. general chapter 2.7.14 Assay of hepatitis A vaccine. This reference preparation was calibrated in 2008 through an international collaborative study and was assigned a potency of 12 IU/mL. During use of this BRP it appeared to be inapplicable in certain cases due to a low nominal antigen content. Consequently, the European Directorate for the Quality of Medicines and HealthCare (EDQM) established replacement batches for this BRP, calibrated against the 1(st) WHO International Standard (IS) for HAV (inactivated), using the standard in vitro ELISA (enzyme-linked immunosorbent assay) method validated previously. The results of the study showed that the candidate BRPs were suitable for the intended purpose, and following completion of the study, they were adopted in November 2014 by the Ph. Eur. Commission as HAV (inactivated, non-adsorbed) BRP batches 2 and 3, with an assigned potency of 1350 IU/mL, for in vitro antigen content determination by ELISA. As the amount of material in each vial largely exceeds the amount required for the performance of a single assay, the BRPs are to be aliquoted by users as single-use aliquots and refrozen below -50 °C prior to their use as reference preparations.

TiO2/porous adsorbents: Recent advances and novel applications.

PubMed

MiarAlipour, Shayan; Friedmann, Donia; Scott, Jason; Amal, Rose

2018-01-05

This article reviews two interrelated areas of research: the first is the use of TiO 2 -supported adsorbent materials as enhanced heterogeneous photocatalysts and their application to various reactions for organic pollutant removal from air and water; the second is the combination of adsorbent materials with TiO 2 photocatalysts which aims to efficiently regenerate adsorbent materials using illumination. By reviewing both areas of research, the following topics are covered; (i) photocatalytic activation of TiO 2; (ii) related properties of photocatalytic TiO 2; (iii) shortcomings of photocatalytic processes; (iv) preparation methods of composite TiO 2 /adsorbent materials and their photocatalytic performance; (v) properties of common adsorbents and their applications for pollutant removal from air and water; (vi) adsorbent regeneration methods and their economic and operational issues; (vii) conclusions and future outlooks. This topic has not been previously reviewed to such an extent, and considerable knowledge can be gained from assembling the large number of studies on adsorption-photocatalysis combinations. As such, this review provides guidance for researchers working in the fields of environmental and chemical engineering focussing on organic pollutant removal and the engineering of new high performance photocatalytic TiO 2 -supported porous adsorbent materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Titanium-incorporated organic–inorganic hybrid adsorbent for improved CO{sub 2} adsorption performance

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

Zhang, Xiaoyun; Qin, Hongyan; Zhang, Sisi

2015-02-15

Highlights: • Titanium-incorporated organic–inorganic hybrid adsorbent was prepared. • The incorporation of Ti to the adsorbent showed significant effect. • The sorbent shows high CO{sub 2} capture capacity both in pure and diluted CO{sub 2} at RT. • The sorbent exhibits a high recycling stability after 15 cycling runs. - Abstract: The CO{sub 2} adsorption performance of acrylonitrile (AN)–tetraethylenepentamine (TEPA) adduct (hereafter referred to as TN) impregnated adsorbent was greatly enhanced by introduction of Titanium atom into the silica matrix. The adsorbents were characterized by X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), transmission electron microscopy (TEM), N{sub 2} adsorption/desorption, UV–vismore » spectroscopy, Fourier transform infrared (FTIR) spectroscopy. The adsorption experiments together with the physicochemical characterization demonstrated that these adsorbents containing an optimal amount of Titanium (Ti/Si ≈ 0.1) remarkably reinforced the CO{sub 2} adsorption capacity and recycling stability. The highest CO{sub 2} uptakes reached 4.65 and 1.80 mmol CO{sub 2}/g adsorbent at 25 °C under 90% CO{sub 2} (CO{sub 2}/N{sub 2}, 90:10 V/V) and 1% CO{sub 2} (CO{sub 2}/N{sub 2}, 1:99 V/V) conditions for sample Ti(0.1)-DMS-TN, respectively. Repeated adsorption/desorption cycles revealed that the Ti-incorporated adsorbent showed only a tiny decrease in adsorption capacity (1.778 mmol CO{sub 2}/g adsorbent after 15 cycles, decreased by 0.95%), significantly enhanced the adsorbent recycling stability.« less

Effect of adsorbed chlorine and oxygen on shear strength of iron and copper junctions

NASA Technical Reports Server (NTRS)

Wheeler, D. R.

1975-01-01

Static friction experiments were performed in ultrahigh vacuum at room temperature on copper, iron, and steel contacts selectively contaminated with oxygen and chlorine in submonolayer amounts. The concentration of the adsorbates was determined with Auger electron spectroscopy and was measured relative to the saturation concentration of oxygen on iron (concentration 1.0). The coefficient of static friction decreased with increasing adsorbate concentration. It was independent of the metal and the adsorbate. The results compared satisfactorily with an extension of the junction growth theory to heterogeneous interfaces. The reduction in interfacial shear strength was measured by the ratio sub a/sub m where sub a is the shear strength of the interface with an adsorbate concentration of 1.0, and sub m is the strength of the clean metal interface. This ratio was 0.835 + or - 0.012 for all the systems tested.

The Uranium from Seawater Program at the Pacific Northwest National Laboratory: Overview of Marine Testing, Adsorbent Characterization, Adsorbent Durability, Adsorbent Toxicity, and Deployment Studies

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

Gill, Gary A.; Kuo, Li-Jung; Janke, Chris J.

The Pacific Northwest National Laboratory’s (PNNL) Marine Science Laboratory (MSL) located along the coast of Washington State is evaluating the performance of uranium adsorption materials being developed for seawater extraction under realistic marine conditions with natural seawater. Two types of exposure systems were employed in this program: flow-through columns for testing of fixed beds of individual fibers and pellets and a recirculating water flume for testing of braided adsorbent material. Testing consists of measurements of the adsorption of uranium and other elements from seawater as a function of time, typically 42 to 56 day exposures, to determine the adsorbent capacitymore » and adsorption rate (kinetics). Analysis of uranium and other trace elements collected by the adsorbents was conducted following strong acid digestion of the adsorbent with 50% aqua regia using either Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The ORNL 38H adsorbent had a 56 day adsorption capacity of 3.30 ± 0.68 g U/ kg adsorbent (normalized to a salinity of 35 psu), a saturation adsorption capacity of 4.89 ± 0.83 g U/kg of adsorbent material (normalized to a salinity of 35 psu) and a half-saturation time of 28 ± 10 days. The AF1 adsorbent material had a 56 day adsorption capacity of 3.9 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu), a saturation capacity of 5.4 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu) and a half saturation time of 23 ± 2 days. The ORNL amidoxime-based adsorbent materials are not specific for uranium, but also adsorb other elements from seawater. The major doubly charged cations in seawater (Ca and Mg) account for a majority of the cations adsorbed (61% by mass and 74% by molar percent). For the ORNL AF1 adsorbent material, U is the 4th most abundant element adsorbed by mass and 7th most abundant by molar percentage« less

Direct observation of the photodegradation of anthracene and pyrene adsorbed onto mangrove leaves.

PubMed

Wang, Ping; Wu, Tun-Hua; Zhang, Yong

2014-01-01

An established synchronous fluorimetry method was used for in situ investigation of the photodegradation of pyrene (PYR) and anthracene (ANT) adsorbed onto fresh leaves of the seedlings of two mangrove species, Aegiceras corniculatum (L.) Blanco (Ac) and Kandelia obovata (Ko) in multicomponent mixtures (mixture of the ANT and PYR). Experimental results indicated that photodegradation was the main transformation pathway for both ANT and PYR in multicomponent mixtures. The amount of the PAHs volatilizing from the leaf surfaces and entering the inner leaf tissues was negligible. Over a certain period of irradiation time, the photodegradation of both PYR and ANT adsorbed onto the leaves of Ac and Ko followed first-order kinetics, with faster rates being observed on Ac leaves. In addition, the photodegradation rate of PYR on the leaves of the mangrove species in multicomponent mixtures was much slower than that of adsorbed ANT. Compared with the PAHs adsorbed as single component, the photodegradation rate of ANT adsorbed in multicomponent mixtures was slower, while that of PYR was faster. Moreover, the photodegradation of PYR and ANT dissolved in water in multicomponent mixtures was investigated for comparison. The photodegradation rate on leaves was much slower than in water. Therefore, the physical-chemical properties of the substrate may strongly influence the photodegradation rate of adsorbed PAHs.

Complete braided adsorbent for marine testing to demonstrate 3g-U/kg-adsorbent

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

Janke, Chris; Yatsandra, Oyola; Mayes, Richard

ORNL has manufactured four braided adsorbents that successfully demonstrated uranium adsorption capacities ranging from 3.0-3.6 g-U/kg-adsorbent in marine testing at PNNL. Four new braided and leno woven fabric adsorbents have also been prepared by ORNL and are currently undergoing marine testing at PNNL.

Remediation of AMD using industrial waste adsorbents

NASA Astrophysics Data System (ADS)

Mohammed, Nuur Hani Bte; Yaacob, Wan Zuhairi Wan

2016-11-01

The study investigates the characteristic of industrial waste as adsorbents and its potential as heavy metals absorbents in AMD samples. The AMD sample was collected from active mine pond and the pH was measured in situ. The metal contents were analyzed by ICP-MS. The AMD water was very acidic (pH< 3.5), and the average heavy metals content in AMD were high especially in Fe (822.029 mg/l). Fly ash was found to be the most effective absorbent material containing high percentage of CaO (57.24%) and SiO2 (13.88%), followed by ladle furnace slag containing of high amount of CaO (51.52%) and Al2O3 (21.23%), while biomass ash consists of SiO2 (43.07%) and CaO (12.97%). Tank analysis display a huge changes due to pH value change from acidity to nearly neutral phases. After 50 days, fly ash remediation successfully increase the AMD pH values from pH 2.57-7.09, while slag change from acidity to nearly alkaline phase from pH 2.60-7.3 and biomass has change to pH 2.54-6.8. Fly ash has successfully remove Fe, Mn, Cu, and Ni. Meanwhile, slag sample displays as an effective adsorbent to adsorb more Pb and Cd in acid mine drainage.

Consumption with Large Sip Sizes Increases Food Intake and Leads to Underestimation of the Amount Consumed

PubMed Central

Bolhuis, Dieuwerke P.; Lakemond, Catriona M. M.; de Wijk, Rene A.; Luning, Pieternel A.; de Graaf, Cees

2013-01-01

Background A number of studies have shown that bite and sip sizes influence the amount of food intake. Consuming with small sips instead of large sips means relatively more sips for the same amount of food to be consumed; people may believe that intake is higher which leads to faster satiation. This effect may be disturbed when people are distracted. Objective The objective of the study is to assess the effects of sip size in a focused state and a distracted state on ad libitum intake and on the estimated amount consumed. Design In this 3×2 cross-over design, 53 healthy subjects consumed ad libitum soup with small sips (5 g, 60 g/min), large sips (15 g, 60 g/min), and free sips (where sip size was determined by subjects themselves), in both a distracted and focused state. Sips were administered via a pump. There were no visual cues toward consumption. Subjects then estimated how much they had consumed by filling soup in soup bowls. Results Intake in the small-sip condition was ∼30% lower than in both the large-sip and free-sip conditions (P<0.001). In addition, subjects underestimated how much they had consumed in the large-sip and free-sip conditions (P<0.03). Distraction led to a general increase in food intake (P = 0.003), independent of sip size. Distraction did not influence sip size or estimations. Conclusions Consumption with large sips led to higher food intake, as expected. Large sips, that were either fixed or chosen by subjects themselves led to underestimations of the amount consumed. This may be a risk factor for over-consumption. Reducing sip or bite sizes may successfully lower food intake, even in a distracted state. PMID:23372657

Rotary adsorbers for continuous bulk separations

DOEpatents

Baker, Frederick S [Oak Ridge, TN

2011-11-08

A rotary adsorber for continuous bulk separations is disclosed. The rotary adsorber includes an adsorption zone in fluid communication with an influent adsorption fluid stream, and a desorption zone in fluid communication with a desorption fluid stream. The fluid streams may be gas streams or liquid streams. The rotary adsorber includes one or more adsorption blocks including adsorbent structure(s). The adsorbent structure adsorbs the target species that is to be separated from the influent fluid stream. The apparatus includes a rotary wheel for moving each adsorption block through the adsorption zone and the desorption zone. A desorption circuit passes an electrical current through the adsorbent structure in the desorption zone to desorb the species from the adsorbent structure. The adsorbent structure may include porous activated carbon fibers aligned with their longitudinal axis essentially parallel to the flow direction of the desorption fluid stream. The adsorbent structure may be an inherently electrically-conductive honeycomb structure.

Aminosilica materials as adsorbents for the selective removal of aldehydes and ketones from simulated bio-oil.

PubMed

Drese, Jeffrey H; Talley, Anne D; Jones, Christopher W

2011-03-21

The fast pyrolysis of biomass is a potential route to the production of liquid biorenewable fuel sources. However, degradation of the bio-oil mixtures due to reaction of oxygenates, such as aldehydes and ketones, reduces the stability of the liquids and can impact long-term storage and shipping. Herein, solid aminosilica adsorbents are described for the selective adsorptive removal of reactive aldehyde and ketone species. Three aminosilica adsorbents are prepared through the reaction of amine-containing silanes with pore-expanded mesoporous silica. A fourth aminosilica adsorbent is prepared through the ring-opening polymerization of aziridine from pore-expanded mesoporous silica. Adsorption experiments with a representative mixture of bio-oil model compounds are presented using each adsorbent at room temperature and 45 °C. The adsorbent comprising only primary amines adsorbs the largest amount of aldehydes and ketones. The overall reactivity of this adsorbent increases with increasing temperature. Additional aldehyde screening experiments show that the reactivity of aldehydes with aminosilicas varies depending on their chemical functionality. Initial attempts to regenerate an aminosilica adsorbent by acid hydrolysis show that they can be at least partially regenerated for further use. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorbent materials from paper industry waste materials and their use in Cu(II) removal from water.

PubMed

Méndez, A; Barriga, S; Fidalgo, J M; Gascó, G

2009-06-15

This paper deals with the removal of Cu(2+) from water using adsorbent materials prepared from paper industry waste materials (one de-inking paper sludge and other sludge from virgin pulp mill). Experimental results showed that de-inking paper sludge leads to mesoporous materials (V(mic)/V(T)=0.13 and 0.14), whereas the sludge from virgin pulp mill produces high microporous adsorbents (V(mic)/V(T)=0.39 and 0.41). Adsorbent materials were then used for Cu(2+) removal from water at acid pH. During water treatment, heavy metals lixiviation from adsorbent materials was not produced. However, important Ca and Mg leaching was observed. Final pH significantly increases after treatment of water with adsorbent materials probably due to their elevated CaCO(3) content. In general, highest Cu(2+) removal was obtained using adsorbent materials from de-inking paper sludge. This result could be due to their higher content in oxygenated surface groups, high average pore diameter, elevated superficial charge density, high CaCO(3) amount and high Ca and Mg exchange content.

Direct Observation of the Photodegradation of Anthracene and Pyrene Adsorbed onto Mangrove Leaves

PubMed Central

Wang, Ping; Wu, Tun-Hua; Zhang, Yong

2014-01-01

An established synchronous fluorimetry method was used for in situ investigation of the photodegradation of pyrene (PYR) and anthracene (ANT) adsorbed onto fresh leaves of the seedlings of two mangrove species, Aegiceras corniculatum (L.) Blanco (Ac) and Kandelia obovata (Ko) in multicomponent mixtures (mixture of the ANT and PYR). Experimental results indicated that photodegradation was the main transformation pathway for both ANT and PYR in multicomponent mixtures. The amount of the PAHs volatilizing from the leaf surfaces and entering the inner leaf tissues was negligible. Over a certain period of irradiation time, the photodegradation of both PYR and ANT adsorbed onto the leaves of Ac and Ko followed first-order kinetics, with faster rates being observed on Ac leaves. In addition, the photodegradation rate of PYR on the leaves of the mangrove species in multicomponent mixtures was much slower than that of adsorbed ANT. Compared with the PAHs adsorbed as single component, the photodegradation rate of ANT adsorbed in multicomponent mixtures was slower, while that of PYR was faster. Moreover, the photodegradation of PYR and ANT dissolved in water in multicomponent mixtures was investigated for comparison. The photodegradation rate on leaves was much slower than in water. Therefore, the physical-chemical properties of the substrate may strongly influence the photodegradation rate of adsorbed PAHs. PMID:25144741

The molecular mechanism of mediation of adsorbed serum proteins to endothelial cells adhesion and growth on biomaterials.

PubMed

Yang, Dayun; Lü, Xiaoying; Hong, Ying; Xi, Tingfei; Zhang, Deyuan

2013-07-01

To explore molecular mechanism of mediation of adsorbed proteins to cell adhesion and growth on biomaterials, this study examined endothelial cell adhesion, morphology and viability on bare and titanium nitride (TiN) coated nickel titanium (NiTi) alloys and chitosan film firstly, and then identified the type and amount of serum proteins adsorbed on the three surfaces by proteomic technology. Subsequently, the mediation role of the identified proteins to cell adhesion and growth was investigated with bioinformatics analyses, and further confirmed by a series of cellular and molecular biological experiments. Results showed that the type and amount of adsorbed serum proteins associated with cell adhesion and growth was obviously higher on the alloys than on the chitosan film, and these proteins mediated endothelial cell adhesion and growth on the alloys via four ways. First, proteins such as adiponectin in the adsorbed protein layer bound with cell surface receptors to generate signal transduction, which activated cell surface integrins through increasing intracellular calcium level. Another way, thrombospondin 1 in the adsorbed protein layer promoted TGF-β signaling pathway activation and enhanced integrins expression. The third, RGD sequence containing proteins such as fibronectin 1, vitronectin and thrombospondin 1 in the adsorbed protein layer bound with activated integrins to activate focal adhesion pathway, increased focal adhesion formation and actin cytoskeleton organization and mediated cell adhesion and spreading. In addition, the activated focal adhesion pathway promoted the expression of cell growth related genes and resulted in cell proliferation. The fourth route, coagulation factor II (F2) and fibronectin 1 in the adsorbed protein layer bound with cell surface F2 receptor and integrin, activated regulation of actin cytoskeleton pathway and regulated actin cytoskeleton organization. Copyright © 2013 Elsevier Ltd. All rights reserved.

Presentation of a large amount of moving objects in a virtual environment

NASA Astrophysics Data System (ADS)

Ye, Huanzhuo; Gong, Jianya; Ye, Jing

2004-05-01

It needs a lot of consideration to manage the presentation of a large amount of moving objects in virtual environment. Motion state model (MSM) is used to represent the motion of objects and 2n tree is used to index the motion data stored in database or files. To minimize the necessary memory occupation for static models, cache with LRU or FIFO refreshing is introduced. DCT and wavelet work well with different playback speeds of motion presentation because they can filter low frequencies from motion data and adjust the filter according to playback speed. Since large amount of data are continuously retrieved, calculated, used for displaying, and then discarded, multithreading technology is naturally employed though single thread with carefully arranged data retrieval also works well when the number of objects is not very big. With multithreading, the level of concurrence should be placed at data retrieval, where waiting may occur, rather than at calculating or displaying, and synchronization should be carefully arranged to make sure that different threads can collaborate well. Collision detection is not needed when playing with history data and sampled current data; however, it is necessary for spatial state prediction. When the current state is presented, either predicting-adjusting method or late updating method could be used according to the users' preference.

Removal of Lead from Water Using Calcium Alginate Beads Doped with Hydrazine Sulphate-Activated Red Mud as Adsorbent

PubMed Central

2017-01-01

Calcium alginate beads doped with hydrazine sulphate-treated red mud are investigated as adsorbent for extracting lead ions from water using batch methods of extraction. Different extraction conditions are optimised for maximum lead extraction. Substantial amount of lead is removed, and the adsorption ability is found to be 138.6 mg/g. Surface characterization using FTIR, EDX, and FESEM confirms that lead is “onto” the surface of the adsorbent. Thermodynamic parameters, adsorption isotherms, and kinetics of adsorption are analysed. Adsorption is “physisorption” in nature and spontaneous. The adsorbent developed can be regenerated using 0.1 M HCl. Thus regenerated adsorbent can be used as the adsorbent for further removal of lead at least 10 times, and this enables the complete removal of lead from water by repetitive use of the regenerated adsorbent. The beads facilitate the easy filtration. The methodology developed is successfully applied for removing lead from industrial waste waters. PMID:29527385

A MBD-seq protocol for large-scale methylome-wide studies with (very) low amounts of DNA.

PubMed

Aberg, Karolina A; Chan, Robin F; Shabalin, Andrey A; Zhao, Min; Turecki, Gustavo; Staunstrup, Nicklas Heine; Starnawska, Anna; Mors, Ole; Xie, Lin Y; van den Oord, Edwin Jcg

2017-09-01

We recently showed that, after optimization, our methyl-CpG binding domain sequencing (MBD-seq) application approximates the methylome-wide coverage obtained with whole-genome bisulfite sequencing (WGB-seq), but at a cost that enables adequately powered large-scale association studies. A prior drawback of MBD-seq is the relatively large amount of genomic DNA (ideally >1 µg) required to obtain high-quality data. Biomaterials are typically expensive to collect, provide a finite amount of DNA, and may simply not yield sufficient starting material. The ability to use low amounts of DNA will increase the breadth and number of studies that can be conducted. Therefore, we further optimized the enrichment step. With this low starting material protocol, MBD-seq performed equally well, or better, than the protocol requiring ample starting material (>1 µg). Using only 15 ng of DNA as input, there is minimal loss in data quality, achieving 93% of the coverage of WGB-seq (with standard amounts of input DNA) at similar false/positive rates. Furthermore, across a large number of genomic features, the MBD-seq methylation profiles closely tracked those observed for WGB-seq with even slightly larger effect sizes. This suggests that MBD-seq provides similar information about the methylome and classifies methylation status somewhat more accurately. Performance decreases with <15 ng DNA as starting material but, even with as little as 5 ng, MBD-seq still achieves 90% of the coverage of WGB-seq with comparable genome-wide methylation profiles. Thus, the proposed protocol is an attractive option for adequately powered and cost-effective methylome-wide investigations using (very) low amounts of DNA.

Diffusion Monte Carlo simulations of gas phase and adsorbed D2-(H2)n clusters

NASA Astrophysics Data System (ADS)

Curotto, E.; Mella, M.

2018-03-01

We have computed ground state energies and analyzed radial distributions for several gas phase and adsorbed D2(H2)n and HD(H2)n clusters. An external model potential designed to mimic ionic adsorption sites inside porous materials is used [M. Mella and E. Curotto, J. Phys. Chem. A 121, 5005 (2017)]. The isotopic substitution lowers the ground state energies by the expected amount based on the mass differences when these are compared with the energies of the pure clusters in the gas phase. A similar impact is found for adsorbed aggregates. The dissociation energy of D2 from the adsorbed clusters is always much higher than that of H2 from both pure and doped aggregates. Radial distributions of D2 and H2 are compared for both the gas phase and adsorbed species. For the gas phase clusters, two types of hydrogen-hydrogen interactions are considered: one based on the assumption that rotations and translations are adiabatically decoupled and the other based on nonisotropic four-dimensional potential. In the gas phase clusters of sufficiently large size, we find the heavier isotopomer more likely to be near the center of mass. However, there is a considerable overlap among the radial distributions of the two species. For the adsorbed clusters, we invariably find the heavy isotope located closer to the attractive interaction source than H2, and at the periphery of the aggregate, H2 molecules being substantially excluded from the interaction with the source. This finding rationalizes the dissociation energy results. For D2-(H2)n clusters with n ≥12 , such preference leads to the desorption of D2 from the aggregate, a phenomenon driven by the minimization of the total energy that can be obtained by reducing the confinement of (H2)12. The same happens for (H2)13, indicating that such an effect may be quite general and impact on the absorption of quantum species inside porous materials.

Oxygen sensor via the quenching of room-temperature phosphorescence of perdeuterated phenanthrene adsorbed on Whatman 1PS filter paper.

PubMed

Ramasamy, S M; Hurtubise, R J

1998-11-01

Perdeuterated phenanthrene (d-phen) exhibits strong room-temperature phosphorescence (RTP) when adsorbed on Whatman 1PS filter paper. An oxygen sensor was developed that depends on oxygen quenching of RTP intensity of adsorbed d-phen. The system designed employed a continuous flow of nitrogen or nitrogen-air onto the adsorbed phosphor. The sensor is simple to prepare and needs no elaborate fabrication procedure, but did show a somewhat drifting baseline for successive determinations of oxygen. Nevertheless, very good reproducibility was achieved with the RTP quenching data by measuring the RTP intensities just before and at the end of each oxygen determination. The calibration plots gave a nonlinear relationship over the entire range of oxygen (0-21%). However, a linear range was obtained up to 1.10% oxygen. A detection limit of 0.09% oxygen in dry nitrogen was acquired. Also, carbon dioxide was found to have a minimal effect on the RTP quenching. Thus, oxygen could be measured accurately in relatively large amounts of carbon dioxide. The performance of the oxygen sensor was evaluated by comparing data obtained with a commercial electrochemical trace oxygen analyzer. Also, additional information on the quenching phenomena for this system was obtained from the RTP lifetime data acquired at various oxygen contents.

Detection of tiny amounts of fissile materials in large-sized containers with radioactive waste

NASA Astrophysics Data System (ADS)

Batyaev, V. F.; Skliarov, S. V.

2018-01-01

The paper is devoted to non-destructive control of tiny amounts of fissile materials in large-sized containers filled with radioactive waste (RAW). The aim of this work is to model an active neutron interrogation facility for detection of fissile ma-terials inside NZK type containers with RAW and determine the minimal detectable mass of U-235 as a function of various param-eters: matrix type, nonuniformity of container filling, neutron gen-erator parameters (flux, pulse frequency, pulse duration), meas-urement time. As a result the dependence of minimal detectable mass on fissile materials location inside container is shown. Nonu-niformity of the thermal neutron flux inside a container is the main reason of the space-heterogeneity of minimal detectable mass in-side a large-sized container. Our experiments with tiny amounts of uranium-235 (<1 g) confirm the detection of fissile materials in NZK containers by using active neutron interrogation technique.

Lysozyme adsorption onto mesoporous materials: effect of pore geometry and stability of adsorbents.

PubMed

Vinu, Ajayan; Miyahara, Masahiko; Hossain, Kazi Zakir; Takahashi, Motoi; Balasubramanian, Veerappan Vaithilingam; Mori, Toshiyuki; Ariga, Katsuhiko

2007-03-01

In this paper, adsorption of lysozyme onto two kinds of mesoporous adsorbents (KIT-5 and AISBA-15) has been investigated and the results on the effects of pore geometry and stability of the adsorbents are also discussed. The KIT-5 mesoporous silica materials possess cage-type pore geometry while the AISBA-15 adsorbent has mesopores of cylindrical type with rather large diameter (9.7 nm). Adsorption of lysozyme onto AISBA-15 aluminosilicate obeys a Langmuir isotherm, resulting in pore occupation of 25 to 30%. In contrast, the KIT-5 adsorbents showed very small adsorption capacities for the lysozyme adsorption, typically falling in 6 to 13% of pore occupation. The cage-type KIT-5 adsorbents have narrow channel (4 to 6 nm) where penetration of the lysozyme (3 x 3 x 4.5 nm) might be restricted. The KIT-5 adsorbent tends to collapse after long-time immersion in water, as indicated by XRD patterns, while the AISBA-15 adsorbent retains its regular structure even after immersion in basic water for 4 days. These facts confirm superiority of the AISBA-15 as an adsorbent as compared with the KIT-5 mesoporous silicates. This research strikingly demonstrates the selection of mesoporous materials is crucial to achieve efficient immobilization of biomaterials in aqueous environment.

Quantum impurity models for magnetic adsorbates on superconductor surfaces

NASA Astrophysics Data System (ADS)

Žitko, Rok

2018-05-01

Magnetic atoms adsorbed on surfaces have a quenched orbital moment while their ground-state spin multiplet is partially split as a consequence of the spin-orbit coupling which, even if intrinsically weak, has a large effect due to the abrupt change of the potential at the surface. Such metal adsorbates should be modelled using quantum impurity models that include the relevant internal degrees of freedom and the interaction terms, in particular the magnetic anisotropy and the Kondo exchange coupling. When adsorbed on superconducting surfaces, these impurities have complex spectra of sub-gap excitations due to magnetic anisotropy splitting and Kondo screening. Both anisotropy splitting and Zeeman splitting due to the external magnetic field are significantly renormalized by the coupling to the substrate electrons. In this work I discuss the quantum-to-classical crossover and the applicability of classical static-local-spin picture for discussing magnetic nanostructures on superconductors.

A new soil test for quantitative measurement of available and adsorbed boron

USDA-ARS?s Scientific Manuscript database

Boron soil tests currently in use, do not extract all plant available B but are used by relating the extractable amount of B to plant B content. There is a need to accurately measure all plant available or adsorbed B because B can be toxic to plants at elevated concentrations and can cause marked y...

3D Oxidized Graphene Frameworks: An Efficient Adsorbent for Methylene Blue

NASA Astrophysics Data System (ADS)

Pandey, Abhishek; Deb, Madhurima; Tiwari, Shreya; Pawar, Pranav Bhagwan; Saxena, Sumit; Shukla, Shobha

2018-04-01

Extraordinary properties of graphene and its derivatives have found application in varied areas such as energy, electronics, optical devices and sensors, to name a few. Large surface area along with specialized functional groups make these materials attractive for removal of dye molecules in solution via adsorption. Industrial effluents contain large amounts of toxic chemicals resulting in pollution of water bodies, which pose environmental hazards in general. Here we report application of 3D oxidized graphene frameworks in the efficient removal of cationic dye molecules such as methylene blue via adsorption. Systematic parametric studies investigating the effect of the initial dye concentration, pH and contact time have been performed. Spectroscopic analysis of the filtrate suggests that tortuous paths in 3D oxidized graphene frameworks result in efficient removal of dye molecules due to enhanced interaction. The hydroxyl groups retained in these 3D oxidized graphene frameworks facilitate adsorption of the dye molecules while passing through the adsorbent. pH studies suggest that maximum removal efficiency for methylene blue was achieved at pH value of 9. The results suggest that these 3D oxidized graphene frameworks can be used for purification of large volumes of contaminated water from cationic dyes in waste water treatment plants.

Nanoporous Boron Nitride as Exceptionally Thermally Stable Adsorbent: Role in Efficient Separation of Light Hydrocarbons.

PubMed

Saha, Dipendu; Orkoulas, Gerassimos; Yohannan, Samuel; Ho, Hoi Chun; Cakmak, Ercan; Chen, Jihua; Ozcan, Soydan

2017-04-26

In this work, nanoporous boron nitride sample was synthesized with a Brunauer-Emmett-Teller (BET) surface area of 1360 m 2 /g and particle size 5-7 μm. The boron nitride was characterized with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and electron microscopy (TEM and SEM). Thermogravimetric analysis (TGA) under nitrogen and air and subsequent analysis with XPS and XRD suggested that its structure is stable in air up to 800 °C and in nitrogen up to 1050 °C, which is higher than most of the common adsorbents reported so far. Nitrogen and hydrocarbon adsorption at 298 K and pressure up to 1 bar suggested that all hydrocarbon adsorption amounts were higher than that of nitrogen and the adsorbed amount of hydrocarbon increases with an increase in its molecular weight. The kinetics of adsorption data suggested that adsorption becomes slower with the increase in molecular weight of hydrocarbons. The equilibrium data suggested that that boron nitride is selective to paraffins in a paraffin-olefin mixture and hence may act as an "olefin generator". The ideal adsorbed solution theory (IAST)-based selectivity for CH 4 /N 2 , C 2 H 6 /CH 4 , and C 3 H 8 /C 3 H 6 was very high and probably higher than the majority of adsorbents reported in the literature. IAST-based calculations were also employed to simulate the binary mixture adsorption data for the gas pairs of CH 4 /N 2 , C 2 H 6 /CH 4 , C 2 H 6 /C 2 H 4 , and C 3 H 8 /C 3 H 6 . Finally, a simple mathematical model was employed to simulate the breakthrough behavior of the above-mentioned four gas pairs in a dynamic column experiment. The overall results suggest that nanoporous boron nitride can be used as a potential adsorbent for light hydrocarbon separation.

To-date spacecraft applications and demonstration testing results, and future product development for new molecular adsorber technologies

NASA Technical Reports Server (NTRS)

Thomson, Shaun; Hansen, Patricia; Straka, Sharon; Chen, Philip; Triolo, Jack; Bettini, Ron; Carosso, Paolo; Carosso, Nancy

1997-01-01

The use of molecular adsorbers, in order to aid in the reduction of the spacecraft contamination levels, is discussed. Molecular adsorbers are characterized by an extremely large surface area, molecularly-porous substructure, and processing charged sites capable of retaining molecular contaminant species. Molecular adsorbers were applied on two Hubble Space Telescope servicing missions, as well as on the tropical rainfall measuring mission. The use of molecular adsorbers carries the potential for low cost, easy fabrication and integration of reliable means for reducing the contamination level around spacecraft.

Copper and zinc removal from roof runoff: from research to full-scale adsorber systems.

PubMed

Steiner, M; Boller, M

2006-01-01

Large, uncoated copper and zinc roofs cause environmental problems if their runoff is infiltrated into the underground or discharged into receiving waters. Since source control is not always feasible, barrier systems for efficient copper and zinc removal are recommended in Switzerland. During the last few years, research carried out in order to test the performance of GIH-calcite adsorber filters as a barrier system. Adsorption and mass transport processes were assessed and described in a mathematical model. However, this model is not suitable for practical design, because it does not give explicit access to design parameters such as adsorber diameter and adsorber bed depth. Therefore, for e.g. engineers, an easy to use design guideline for GIH-calcite adsorber systems was developed, mainly based on the mathematical model. The core of this guideline is the design of the depth of the GIH-calcite adsorber layer. The depth is calculated by adding up the GIH depth for sorption equilibrium and the depth for the mass transfer zone (MTZ). Additionally, the arrangement of other adsorber system components such as particle separation and retention volume was considered in the guideline. Investigations of a full-scale adsorber confirm the successful application of this newly developed design guideline for the application of GIH-calcite adsorber systems in practice.

Analysis of Adsorbed Natural Gas Tank Technology

NASA Astrophysics Data System (ADS)

Knight, Ernest; Schultz, Conrad; Rash, Tyler; Dohnke, Elmar; Stalla, David; Gillespie, Andrew; Sweany, Mark; Seydel, Florian; Pfeifer, Peter

With gasoline being an ever decreasing finite resource and with the desire to reduce humanity's carbon footprint, there has been an increasing focus on innovation of alternative fuel sources. Natural gas burns cleaner, is more abundant, and conforms to modern engines. However, storing compressed natural gas (CNG) requires large, heavy gas cylinders, which limits space and fuel efficiency. Adsorbed natural gas (ANG) technology allows for much greater fuel storage capacity and the ability to store the gas at a much lower pressure. Thus, ANG tanks are much more flexible in terms of their size, shape, and weight. Our ANG tank employs monolithic nanoporous activated carbon as its adsorbent material. Several different configurations of this Flat Panel Tank Assembly (FPTA) along with a Fuel Extraction System (FES) were examined to compare with the mass flow rate demands of an engine.

Effect of adsorbed/intercalated anionic dyes into the mechanical properties of PVA: layered zinc hydroxide nitrate nanocomposites.

PubMed

Marangoni, Rafael; Mikowski, Alexandre; Wypych, Fernando

2010-11-15

Zinc hydroxide nitrate (ZHN) was adsorbed with anions of blue dyes (Chicago sky blue, CSB; Evans blue, EB; and Niagara blue, NB) and intercalated with anions of orange dyes (Orange G, OG; Orange II, OII; methyl orange, MO). Transparent, homogeneous and colored nanocomposite films were obtained by casting after dispersing the pigments (dye-intercalated/adsorbed into LHSs) into commercial poly(vinyl alcohol) (PVA). The films were characterized by XRD, UV-Vis spectroscopy, and mechanical testing. The mechanical properties of the PVA compounded with the dye-intercalated/adsorbed ZHN were evaluated, and reasonable increases in Young's modulus and ultimate tensile strength were observed, depending on the amount and choice of layered filler. These results demonstrate the possibility of using a new class of layered hydroxide salts intercalated and adsorbed with anionic dyes to prepare multifunctional polymer nanocomposite materials. Copyright © 2010 Elsevier Inc. All rights reserved.

Cytokine adsorbing columns.

PubMed

Taniguchi, Takumi

2010-01-01

Sepsis induces the activation of complement and the release of inflammatory cytokines such as TNF-alpha and IL-1beta. The inflammatory cytokines and nitric oxide induced by sepsis can decrease systemic vascular resistance, resulting in profound hypotension. The combination of hypotension and microvascular occlusion results in tissue ischemia and ultimately leads to multiple organ failure. Recently, several experimental and clinical studies have reported that treatment for adsorption of cytokines is beneficial during endotoxemia and sepsis. Therefore, the present article discusses cytokine adsorbing columns. These columns, such as CytoSorb, CYT-860-DHP, Lixelle, CTR-001 and MPCF-X, the structures of which vary significantly, have excellent adsorption rates for inflammatory cytokines such as TNF-alpha, IL-1beta, IL-6 and IL8. Many studies have demonstrated that treatment with cytokine adsorbing columns has beneficial effects on the survival rate and inflammatory responses in animal septic models. Moreover, several cases have been reported in which treatment with cytokine adsorbing columns is very effective in hemodynamics and organ failures in critically ill patients. Although further investigations and clinical trials are needed, in the future treatment with cytokine adsorbing columns may play a major role in the treatment of hypercytokinemia such as multiple organ failure and acute respiratory distress syndrome. Copyright 2010 S. Karger AG, Basel.

Discovering Related Clinical Concepts Using Large Amounts of Clinical Notes

PubMed Central

Ganesan, Kavita; Lloyd, Shane; Sarkar, Vikren

2016-01-01

The ability to find highly related clinical concepts is essential for many applications such as for hypothesis generation, query expansion for medical literature search, search results filtering, ICD-10 code filtering and many other applications. While manually constructed medical terminologies such as SNOMED CT can surface certain related concepts, these terminologies are inadequate as they depend on expertise of several subject matter experts making the terminology curation process open to geographic and language bias. In addition, these terminologies also provide no quantifiable evidence on how related the concepts are. In this work, we explore an unsupervised graphical approach to mine related concepts by leveraging the volume within large amounts of clinical notes. Our evaluation shows that we are able to use a data driven approach to discovering highly related concepts for various search terms including medications, symptoms and diseases. PMID:27656096

Milestone Report - Complete New Adsorbent Materials for Marine Testing to Demonstrate 4.5 g-U/kg Adsorbent

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

Janke, Christopher James; Das, Sadananda; Oyola, Yatsandra

2014-08-01

This report describes work on the successful completion of Milestone M2FT-14OR03100115 (8/20/2014) entitled, “Complete new adsorbent materials for marine testing to demonstrate 4.5 g-U/kg adsorbent”. This effort is part of the Seawater Uranium Recovery Program, sponsored by the U.S. Department of Energy, Office of Nuclear Energy, and involved the development of new adsorbent materials at the Oak Ridge National Laboratory (ORNL) and marine testing at the Pacific Northwest National Laboratory (PNNL). ORNL has recently developed two new families of fiber adsorbents that have demonstrated uranium adsorption capacities greater than 4.5 g-U/kg adsorbent after marine testing at PNNL. One adsorbent wasmore » synthesized by radiation-induced graft polymerization of itaconic acid and acrylonitrile onto high surface area polyethylene fibers followed by amidoximation and base conditioning. This fiber showed a capacity of 4.6 g-U/kg adsorbent in marine testing at PNNL. The second adsorbent was prepared by atom-transfer radical polymerization of t-butyl acrylate and acrylonitrile onto halide-functionalized round fibers followed by amidoximation and base hydrolysis. This fiber demonstrated uranium adsorption capacity of 5.4 g-U/kg adsorbent in marine testing at PNNL.« less

Amine-pillared Nanosheet Adsorbents for CO2 Capture Applications

NASA Astrophysics Data System (ADS)

Jiang, Hui

Amine-functionalized solid adsorbents have gained attention within the last decade for their application in carbon dioxide capture, due to their many advantages such as low energy cost for regeneration, tunable structure, elimination of corrosion problems, and additional advantages. However, one of the challenges facing this technology is to accomplish both high CO 2 capture capacity along with high CO2 diffusion rates concurrently. Current amine-based solid sorbents such as porous materials similar to SBA-15 have large pores diffusion entering molecules; however, the pores become clogged upon amine inclusion. To meet this challenge, our group's solution involves the creation of a new type of material which we are calling-amino-pillared nanosheet (APN) adsorbents which are generated from layered nanosheet precursors. These materials are being proposed because of their unique lamellar structure which exhibits ability to be modified by organic or inorganic pillars through consecutive swelling and pillaring steps to form large mesoporous interlayer spaces. After the expansion of the layer space through swelling and pillaring, the large pore space can be functionalized with amine groups. This selective functionalization is possible by the choice of amine group introduced. Our choice, large amine molecules, do not access the micropore within each layer; however, either physically or chemically immobilized onto the surface of the mesoporous interlayer space between each layer. The final goal of the research is to investigate the ability to prepare APN adsorbents from a model nanoporous layered materials including nanosheets precursor material MCM-22(P) and nanoporous layered silicate material AMH-3. MCM-22(P) contains 2-dimensional porous channels, 6 membered rings (MB) openings perpendicular to the layers and 10 MB channels in the plane of the layers. However, the transport limiting openings (6 MB) to the layers is smaller than CO2 gas molecules. In contrast, AMH-3 has

Making large amounts of meteorological plots easily accessible to users

NASA Astrophysics Data System (ADS)

Lamy-Thepaut, Sylvie; Siemen, Stephan; Sahin, Cihan; Raoult, Baudouin

2015-04-01

The European Centre for Medium-Range Weather Forecasts (ECMWF) is an international organisation providing its member organisations with forecasts in the medium time range of 3 to 15 days, and some longer-range forecasts for up to a year ahead, with varying degrees of detail. As part of its mission, ECMWF generates an increasing number of forecast data products for its users. To support the work of forecasters and researchers and to let them make best use of ECMWF forecasts, the Centre also provides tools and interfaces to visualise their products. This allows users to make use of and explore forecasts without having to transfer large amounts of raw data. This is especially true for products based on ECMWF's 50 member ensemble forecast, where some specific processing and visualisation are applied to extract information. Every day, thousands of raw data are being pushed to the ECMWF's interactive web charts application called ecCharts, and thousands of products are processed and pushed to ECMWF's institutional web site ecCharts provides a highly interactive application to display and manipulate recent numerical forecasts to forecasters in national weather services and ECMWF's commercial customers. With ecCharts forecasters are able to explore ECMWF's medium-range forecasts in far greater detail than has previously been possible on the web, and this as soon as the forecast becomes available. All ecCharts's products are also available through a machine-to-machine web map service based on the OGC Web Map Service (WMS) standard. ECMWF institutional web site provides access to a large number of graphical products. It was entirely redesigned last year. It now shares the same infrastructure as ECMWF's ecCharts, and can benefit of some ecCharts functionalities, for example the dashboard. The dashboard initially developed for ecCharts allows users to organise their own collection of products depending on their work flow, and is being further developed. In its first

Synthesis of magnetic ordered mesoporous carbon (Fe-OMC) adsorbent and its evaluation for fuel desulfurization

NASA Astrophysics Data System (ADS)

Farzin Nejad, N.; Shams, E.; Amini, M. K.

2015-09-01

In this work, magnetic ordered mesoporous carbon adsorbent was synthesized using soft templating method to adsorb sulfur from model oil (dibenzothiophene in n-hexane). Through this research, pluronic F-127, resorcinol-formaldehyde and hydrated iron nitrate were respectively used as soft template, carbon source and iron source. The adsorbent was characterized by X-ray diffraction, nitrogen adsorption-desorption isotherm and transmission electron microscopy. Nitrogen adsorption-desorption measurement revealed the high surface area (810 m2 g-1), maxima pore size of 3.3 nm and large pore volume (1.01 cm3 g-1) of the synthesized sample. The adsorbent showed a maximum adsorption capacity of 111 mg dibenzothiophene g-1 of adsorbent. Sorption process was described by the pseudo-second-order rate equation and could be better fitted by the Freundlich model, showing the heterogeneous feature of the adsorption process. In addition, the adsorption capacity of regenerated adsorbent was 78.6% of the initial level, after five regeneration cycles.

From illite/smectite clay to mesoporous silicate adsorbent for efficient removal of chlortetracycline from water.

PubMed

Wang, Wenbo; Tian, Guangyan; Zong, Li; Zhou, Yanmin; Kang, Yuru; Wang, Qin; Wang, Aiqin

2017-01-01

A series of mesoporous silicate adsorbents with superior adsorption performance for hazardous chlortetracycline (CTC) were sucessfully prepared via a facile one-pot hydrothermal reaction using low-cost illite/smectite (IS) clay, sodium silicate and magnesium sulfate as the starting materials. In this process, IS clay was "teared up" and then "rebuilt" as new porous silicate adsorbent with high specific surface area of 363.52m 2 /g (about 8.7 folds higher than that of IS clay) and very negative Zeta potential (-34.5mV). The inert SiOSi (Mg, Al) bonds in crystal framework of IS were broken to form Si(Al) O - groups with good adsorption activity, which greatly increased the adsorption sites served for holding much CTC molecules. Systematic evaluation on adsorption properties reveals the optimal silicate adsorbent can adsorb 408.81mg/g of CTC (only 159.7mg/g for raw IS clay) and remove 99.3% (only 46.5% for raw IS clay) of CTC from 100mg/L initial solution (pH3.51; adsorption temperature 30°C; adsorbent dosage, 3g/L). The adsorption behaviors of CTC onto the adsorbent follows the Langmuir isotherm model, Temkin equation and pseudo second-order kinetic model. The mesopore adsorption, electrostatic attraction and chemical association mainly contribute to the enhanced adsorption properties. As a whole, the high-efficient silicate adsorbent could be candidates to remove CTC from the wastewater with high amounts of CTC. Copyright © 2016. Published by Elsevier B.V.

Radiation synthesis of a new amidoximated UHMWPE fibrous adsorbent with high adsorption selectivity for uranium over vanadium in simulated seawater

NASA Astrophysics Data System (ADS)

Gao, Qianhong; Hu, Jiangtao; Li, Rong; Xing, Zhe; Xu, Lu; Wang, Mouhua; Guo, Xiaojing; Wu, Guozhong

2016-05-01

A new kind of highly efficient adsorbent material has been fabricated in this study for the purpose of extracting uranium from seawater. Ultra-high molecular weight polyethylene (UHMWPE) fiber was used as a trunk material for the adsorbent, which was prepared by a series of modification reactions, as follows: (1) grafting of glycidyl methacrylate (GMA) and methyl acrylate (MA) onto UHMWPE fibers via 60Co γ-ray pre-irradiation; (2) aminolyzation of UHMWPE fiber by the ring-opening reaction between of epoxy groups PGMA and ethylene diamine (EDA); (3) Michael addition of amino groups with acrylonitrile (AN) to yield nitrile groups; (4) amidoximation of the attached nitrile moieties by hydroxylamine in dimethyl sulfoxide-water mixture. Modified UHMWPE fibers were characterized by means of attenuated total reflectance-Fourier transformed infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) to confirm the attachment of amidoxime (AO) groups onto the UHMWPE fibers. The results of X-ray diffraction (XRD) and single fiber tensile strength verified that the modified UHMWPE fiber retained excellent mechanical properties at a low absorbed radiation dose. The adsorption performance of the UHMWPE fibrous adsorbent was evaluated by subjecting it to an adsorption test in simulated seawater using a continuous-flow mode. The amount of uranium adsorbed by this AO-based UHMWPE fibrous adsorbent was 1.97 mg-U/g after 42 days. This new adsorbent also showed high selectivity for the uranyl ion, and its selectivity for metal ions was found to decrease in the following order: U>Cu>Fe>Ca>Mg>Ni>Zn>Pb>V>Co. The adsorption selectivity for uranium is significantly higher than that for vanadium. In addition, preparation of this modified adsorbent consumes much smaller amounts of the toxic acrylonitrile monomer than the conventional preparation methods of AO-based polyethylene fibers.

A MODIFIED METHOD OF OBTAINING LARGE AMOUNTS OF RICKETTSIA PROWAZEKI BY ROENTGEN IRRADIATION OF RATS

PubMed Central

Macchiavello, Atilio; Dresser, Richard

1935-01-01

The radiation method described by Zinsser and Castaneda for obtaining large amounts of Rickettsia has been carried out successfully with an ordinary radiographic machine. This allows the extension of the method to those communities which do not possess a high voltage Roentgen therapy unit as originally employed. PMID:19870416

Solid waste from leather industry as adsorbent of organic dyes in aqueous-medium.

PubMed

Oliveira, Luiz C A; Gonçalves, Maraísa; Oliveira, Diana Q L; Guerreiro, Mário C; Guilherme, Luiz R G; Dallago, Rogério M

2007-03-06

The industrial tanning of leather usually produces considerable amounts of chromium-containing solid waste and liquid effluents and raises many concerns on its environmental effect as well as on escalating landfill costs. Actually, these shortcomings are becoming increasingly a limiting factor to this industrial activity that claims for alternative methods of residue disposals. In this work, it is proposed a novel alternative destination of the solid waste, based on the removal of organic contaminants from the out coming aqueous-residue. The adsorption isotherm pattern for the wet blue leather from the Aurea tanning industry in Erechim-RS (Brazil) showed that these materials present high activity on adsorbing the reactive red textile dye as well as other compounds. The adsorbent materials were characterized by IR spectroscopy and SEM and tested for the dye adsorption (reactive textile and methylene blue dyes). The concentrations of dyes were measured by UV-vis spectrophotometry and the chromium extraction from leather waste was realized by basic hydrolysis and determined by atomic absorption. As a low cost abundant adsorbent material with high adsorption ability on removing dye methylene blue (80mgg(-1)) and textile dye reactive red (163mgg(-1)), the leather waste is revealed to be a interesting alternative relatively to more costly adsorbent materials.

Method And Apparatus For Regenerating Nox Adsorbers

DOEpatents

Driscoll, J. Joshua; Endicott, Dennis L.; Faulkner, Stephen A.; Verkiel, Maarten

2006-03-28

Methods and apparatuses for regenerating a NOx adsorber coupled with an exhaust of an engine. An actuator drives a throttle valve to a first position when regeneration of the NOx adsorber is desired. The first position is a position that causes the regeneration of the NOx adsorber. An actuator drives the throttle valve to a second position while regeneration of the NOx adsorber is still desired. The second position being a position that is more open than the first position and operable to regenerate a NOx adsorber.

Removal of microcystin-LR from drinking water using a bamboo-based charcoal adsorbent modified with chitosan.

PubMed

Zhang, Hangjun; Zhu, Guoying; Jia, Xiuying; Ding, Ying; Zhang, Mi; Gao, Qing; Hu, Ciming; Xu, Shuying

2011-01-01

A new kind of low-cost syntactic adsorbent from bamboo charcoal and chitosan was developed for the removal of microcystin-LR from drinking water. Removal efficiency was higher for the syntactic adsorbent when the amount of bamboo charcoal was increased. The optimum dose ratio of bamboo charcoal to chitosan was 6:4, and the optimum amount was 15 mg/L; equilibrium time was 6 hr. The adsorption isotherm was non-linear and could be simulated by the Freundlich model (R2 = 0.9337). Adsorption efficiency was strongly affected by pH and natural organic matter (NOM). Removal efficiency was 16% higher at pH 3 than at pH 9. Efficiency rate was reduced by 15% with 25 mg/L NOM (UV254 = 0.089 cm(-1)) in drinking water. This study demonstrated that the bamboo charcoal modified with chitosan can effectively remove microcystin-LR from drinking water.

Adsorption characteristics of water vapor on gear-pellet and honeycomb-pellet types of adsorbents containing A-type zeolite

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

Nakamura, A.; Munakata, K.; Hara, K.

2015-03-15

It is necessary to recover or process tritiated species that are extensively coexistent in nuclear fusion installations. A conventional way to recover tritium release to atmosphere is catalytic oxidation of tritiated species and adsorption of tritiated water vapor on adsorbents with high surface areas. Therefore, new adsorbents with low pressure loss and high surface areas need to be developed and utilized for such large-scale adsorption systems. In this study, attention was focused on new adsorbents, which are gear-type pellet MS5A adsorbent, gear-type pellet MS4A adsorbent and honeycomb-type pellet MS5A adsorbent. The adsorption characteristics of the new adsorbent were comparatively studiedmore » with conventional type of adsorbents (pellet-type MS5A adsorbent and pebble-type MS5A adsorbent), in terms of adsorption capacity, pressure loss and adsorption rate. It was found that the adsorption capacity of water vapor on the gear-type adsorbents is higher than that on a honeycomb-type adsorbent. The experimental breakthrough curves indicate that the adsorption rates of water vapor on gear-type and honeycomb-type adsorbents are smaller than that on conventional type adsorbents. Various adsorption models were also tested to correlate the experimental isotherms. It was found that the Langmuir-Freundlich model could properly correlate the experimental adsorption isotherms.« less

Analytics to Better Interpret and Use Large Amounts of Heterogeneous Data

NASA Astrophysics Data System (ADS)

Mathews, T. J.; Baskin, W. E.; Rinsland, P. L.

2014-12-01

Data scientists at NASA's Atmospheric Science Data Center (ASDC) are seasoned software application developers who have worked with the creation, archival, and distribution of large datasets (multiple terabytes and larger). In order for ASDC data scientists to effectively implement the most efficient processes for cataloging and organizing data access applications, they must be intimately familiar with data contained in the datasets with which they are working. Key technologies that are critical components to the background of ASDC data scientists include: large RBMSs (relational database management systems) and NoSQL databases; web services; service-oriented architectures; structured and unstructured data access; as well as processing algorithms. However, as prices of data storage and processing decrease, sources of data increase, and technologies advance - granting more people to access to data at real or near-real time - data scientists are being pressured to accelerate their ability to identify and analyze vast amounts of data. With existing tools this is becoming exceedingly more challenging to accomplish. For example, NASA Earth Science Data and Information System (ESDIS) alone grew from having just over 4PBs of data in 2009 to nearly 6PBs of data in 2011. This amount then increased to roughly10PBs of data in 2013. With data from at least ten new missions to be added to the ESDIS holdings by 2017, the current volume will continue to grow exponentially and drive the need to be able to analyze more data even faster. Though there are many highly efficient, off-the-shelf analytics tools available, these tools mainly cater towards business data, which is predominantly unstructured. Inadvertently, there are very few known analytics tools that interface well to archived Earth science data, which is predominantly heterogeneous and structured. This presentation will identify use cases for data analytics from an Earth science perspective in order to begin to identify

Toluene and acetaldehyde removal from air on to graphene-based adsorbents with microsized pores.

PubMed

Kim, Ji Min; Kim, Ji Hoon; Lee, Chang Yeon; Jerng, Dong Wook; Ahn, Ho Seon

2018-02-15

Volatile organic compound (VOC) gases can cause harm to the human body with exposure over the long term even at very low concentrations (ppmv levels); thus, effective absorbents for VOC gas removal are an important issue. In this study, accordingly, graphene-based adsorbents with microsized pores were used as adsorbents to remove toluene and acetaldehyde gases at low concentrations (30ppm). Sufficient amounts of the adsorbents were prepared for use on filters and were loaded uniformly at 0.1-0.5g on a 50×50mm 2 area, to evaluate their adsorption features with low gas concentrations. The morphology and chemical composition of the adsorbents were characterized using scanning electron microscopy, N 2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and Raman spectroscopy. Microwave irradiation and heat treatment near 800°C under KOH activation resulted in enlargement of the pristine graphene surface and its specific surface area; maximum volume capacities of 3510m 3 /g and 630m 3 /g were observed for toluene and acetaldehyde gas. The high removal efficiency for toluene (98%) versus acetaldehyde (30%) gas was attributed to π-π interactions between the pristine graphene surface and toluene molecules. Copyright © 2017 Elsevier B.V. All rights reserved.

Selective removal of organochlorine pesticides (OCPs) from aqueous solution by triolein-embedded composite adsorbent.

PubMed

Ru, J; Liu, H J; Qu, J H; Wang, A M; Dai, R H; Wang, Z J

2007-01-01

A novel composite adsorbent (CA-T) was used for the selective removal of organochlorine pesticides (OCPs) from aqueous solution. The adsorbent was composed of the supporting activated carbon and the surrounding triolein-embedded cellulose acetate membrane. Scanning electron microscopy (SEM), N2 adsorption isotherms and fluorescence methods were used to characterize the physicochemical properties of CA-T. Triolein was perfectly embedded in the cellulose acetate membrane and deposited on the surface of activated carbon. The adsorbent was stable in water and no triolein leakage was detected during the test periods. Some organochlorine pesticides (OCPs), such as dieldrin, endrin, aldrin, and heptachlor epoxide, were used as model contaminants and removed by CA-T in laboratory batch experiments. The adsorption isotherm followed the Freundlich equation and the kinetic data fitted well to the pseudo-second-order reaction model. Results also indicated that CA-T appeared to be a promising adsorbent with good selectivity and satisfactory removal rate for lipophilic OCPs from aqueous solutions when present in trace amounts. The adsorption rate and removal efficiency for lipophilic OCPs were positively related to their octanol-water partition coefficients (log K(ow)). Lower residual concentrations of OCPs were achieved when compared to granular activated carbon (GAC).

Database of Novel and Emerging Adsorbent Materials

National Institute of Standards and Technology Data Gateway

SRD 205 NIST/ARPA-E Database of Novel and Emerging Adsorbent Materials (Web, free access)   The NIST/ARPA-E Database of Novel and Emerging Adsorbent Materials is a free, web-based catalog of adsorbent materials and measured adsorption properties of numerous materials obtained from article entries from the scientific literature. Search fields for the database include adsorbent material, adsorbate gas, experimental conditions (pressure, temperature), and bibliographic information (author, title, journal), and results from queries are provided as a list of articles matching the search parameters. The database also contains adsorption isotherms digitized from the cataloged articles, which can be compared visually online in the web application or exported for offline analysis.

Characterization of natural organic matter adsorption in granular activated carbon adsorbers.

PubMed

Velten, Silvana; Knappe, Detlef R U; Traber, Jacqueline; Kaiser, Hans-Peter; von Gunten, Urs; Boller, Markus; Meylan, Sébastien

2011-07-01

The removal of natural organic matter (NOM) from lake water was studied in two pilot-scale adsorbers containing granular activated carbon (GAC) with different physical properties. To study the adsorption behavior of individual NOM fractions as a function of time and adsorber depth, NOM was fractionated by size exclusion chromatography (SEC) into biopolymers, humics, building blocks, and low molecular weight (LMW) organics, and NOM fractions were quantified by both ultraviolet and organic carbon detectors. High molecular weight biopolymers were not retained in the two adsorbers. In contrast, humic substances, building blocks and LMW organics were initially well and irreversibly removed, and their effluent concentrations increased gradually in the outlet of the adsorbers until a pseudo-steady state concentration was reached. Poor removal of biopolymers was likely a result of their comparatively large size that prevented access to the internal pore structure of the GACs. In both GAC adsorbers, adsorbability of the remaining NOM fractions, compared on the basis of partition coefficients, increased with decreasing molecular size, suggesting that increasingly larger portions of the internal GAC surface area could be accessed as the size of NOM decreased. Overall DOC uptake at pseudo-steady state differed between the two tested GACs (18.9 and 28.6 g-C/kg GAC), and the percent difference in DOC uptake closely matched the percent difference in the volume of pores with widths in the 1-50 nm range that was measured for the two fresh GACs. Despite the differences in NOM uptake capacity, individual NOM fractions were removed in similar proportions by the two GACs. Copyright © 2011 Elsevier Ltd. All rights reserved.

Method for modifying trigger level for adsorber regeneration

DOEpatents

Ruth, Michael J.; Cunningham, Michael J.

2010-05-25

A method for modifying a NO.sub.x adsorber regeneration triggering variable. Engine operating conditions are monitored until the regeneration triggering variable is met. The adsorber is regenerated and the adsorbtion efficiency of the adsorber is subsequently determined. The regeneration triggering variable is modified to correspond with the decline in adsorber efficiency. The adsorber efficiency may be determined using an empirically predetermined set of values or by using a pair of oxygen sensors to determine the oxygen response delay across the sensors.

Adsorbed molecules in external fields: Effect of confining potential

NASA Astrophysics Data System (ADS)

Tyagi, Ashish; Silotia, Poonam; Maan, Anjali; Prasad, Vinod

2016-12-01

We study the rotational excitation of a molecule adsorbed on a surface. As is well known the interaction potential between the surface and the molecule can be modeled in number of ways, depending on the molecular structure and the geometry under which the molecule is being adsorbed by the surface. We explore the effect of change of confining potential on the excitation, which is largely controlled by the static electric fields and continuous wave laser fields. We focus on dipolar molecules and hence we restrict ourselves to the first order interaction in field-molecule interaction potential either through permanent dipole moment or/and the molecular polarizability parameter. It is shown that confining potential shapes, strength of the confinement, strongly affect the excitation. We compare our results for different confining potentials.

Chitosan-edible oil based materials as upgraded adsorbents for textile dyes.

PubMed

Dos Santos, Clayane Carvalho; Mouta, Rodolpho; Junior, Manoel Carvalho Castro; Santana, Sirlane Aparecida Abreu; Silva, Hildo Antonio Dos Santos; Bezerra, Cícero Wellington Brito

2018-01-15

Biopolymer chitosan is a low cost, abundant, environmentally friendly, very selective and efficient anionic dyes adsorbent, being a promising material for large-scale removal of dyes from wastewater. However, raw chitosan (CS) is an ineffective cationic dyes adsorbent and its performance is pH sensitive, thus, CS modifications that address these issues need to be developed. Here, we report the preparation and characterization of two new CS modifications using edible oils (soybean oil or babassu oil), and their adsorption performance for two dyes, one anionic (remazol red, RR) and one cationic (methylene blue, MB). Both modifications extended the pH range of RR adsorption. The babassu oil modification increased adsorption capacity of the cationic dye MB, whereas the soybean oil modification increased that of RR. Such improvements demonstrate the potential of these two new CS modifications as adsorbent candidates for controlling dyes pollution in effluents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electronic properties of NH{sub 4}-adsorbed graphene nanoribbon as a promising candidate for a gas sensor

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

Harada, Naoki, E-mail: harada.naoki@jp.fujitsu.com; Sato, Shintaro

2016-05-15

The electronic properties of NH{sub 4}-adsorbed N = 7 armchair graphene nanoribbons (AGNRs) were theoretically investigated using self-consistent atomistic simulations to explore the feasibility of AGNRs as a gas sensing material. Whereas a pristine AGNR has a finite band gap and is an intrinsic semiconductor, an NH{sub 4}-adsorbed AGNR exhibits heavily doped n-type properties similar to a graphene sheet with the molecules adsorbed. The electric characteristics of a back-gated AGNR gas sensor were also simulated and the drain current changed exponentially with increasing number of adsorbed molecules. We may conclude that an AGNR is promising as a highly sensitive gas-sensingmore » material with large outputs.« less

Carbon coated magnetic nanoparticles as a novel magnetic solid phase extraction adsorbent for simultaneous extraction of methamphetamine and ephedrine from urine samples.

PubMed

Taghvimi, Arezou; Hamishehkar, Hamed

2017-01-15

This paper develops a highly selective, specific and efficient method for simultaneous determination of ephedrine and methamphetamine by a new carbon coated magnetic nanoparticles (C/MNPs) as a magnetic solid phase extraction (MSPE) adsorbent in biological urine medium. The characterization of synthesized magnetic nano adsorbent was completely carried out by various characterization techniques like Fourier transform infrared (FT-IR) spectroscopy, powder x-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). Nine important parameters influencing extraction efficiency including amount of adsorbent, amounts of sample volume, pH, type and amount of extraction organic solvent, time of extraction and desorption, agitation rate and ionic strength of extraction medium, were studied and optimized. Under optimized extraction conditions, a good linearity was observed in the concentration range of 100-2000ng/mL for ephedrine and 100-2500ng/mL for methamphetamine. Analysis of positive urine samples was carried out by proposed method with the recovery of 98.71 and 97.87% for ephedrine and methamphetamine, respectively. The results indicated that carbon coated magnetic nanoparticles could be applied in clinical and forensic laboratories for simultaneous determination of abused drugs in urine media. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis and comparison of inertinite-derived adsorbent with conventional adsorbents.

PubMed

Gangupomu, Roja Haritha; Kositkanawuth, Ketwalee; Sattler, Melanie L; Ramirez, David; Dennis, Brian H; MacDonnell, Frederick M; Billo, Richard; Priest, John W

2012-05-01

To increase U.S. petroleum energy-independence, the University of Texas at Arlington (UT Arlington) has developed a coal liquefaction process that uses a hydrogenated solvent and a proprietary catalyst to convert lignite coal to crude oil. This paper reports on part of the environmental evaluation of the liquefaction process: the evaluation of the solid residual from liquefying the coal, called inertinite, as a potential adsorbent for air and water purification. Inertinite samples derived from Arkansas and Texas lignite coals were used as test samples. In the activated carbon creation process, inertinite samples were heated in a tube furnace (Lindberg, Type 55035, Arlington, UT) at temperatures ranging between 300 and 850 degrees C for time spans of 60, 90, and 120 min, using steam and carbon dioxide as oxidizing gases. Activated inertinite samples were then characterized by ultra-high-purity nitrogen adsorption isotherms at 77 K using a high-speed surface area and pore size analyzer (Quantachrome, Nova 2200e, Kingsville, TX). Surface area and total pore volume were determined using the Brunauer Emmet, and Teller method, for the inertinite samples, as well as for four commercially available activated carbons (gas-phase adsorbents Calgon Fluepac-B and BPL 4 x 6; liquid-phase adsorbents Filtrasorb 200 and Carbsorb 30). In addition, adsorption isotherms were developed for inertinite and the two commercially available gas-phase carbons, using methyl ethyl ketone (MEK) as an example compound. Adsorption capacity was measured gravimetrically with a symmetric vapor sorption analyzer (VTI, Inc., Model SGA-100, Kingsville, TX). Also, liquid-phase adsorption experiments were conducted using methyl orange as an example organic compound. The study showed that using inertinite from coal can be beneficially reused as an adsorbent for air or water pollution control, although its surface area and adsorption capacity are not as high as those for commercially available activated

NOx adsorber and method of regenerating same

DOEpatents

Endicott, Dennis L [Peoria, IL; Verkiel, Maarten [Metamora, IL; Driscoll, James J [Dunlap, IL

2007-01-30

New technologies, such as NOx adsorber catalytic converters, are being used to meet increasingly stringent regulations on undesirable emissions, including NOx emissions. NOx adsorbers must be periodically regenerated, which requires an increased fuel consumption. The present disclosure includes a method of regenerating a NOx adsorber within a NOx adsorber catalytic converter. At least one sensor positioned downstream from the NOx adsorber senses, in the downstream exhaust, at least one of NOx, nitrous oxide and ammonia concentrations a plurality of times during a regeneration phase. The sensor is in communication with an electronic control module that includes a regeneration monitoring algorithm operable to end the regeneration phase when a time rate of change of the at least one of NOx, nitrous oxide and ammonia concentrations is after an expected plateau region begins.

Carbonised jackfruit peel as an adsorbent for the removal of Cd(II) from aqueous solution.

PubMed

Inbaraj, B Stephen; Sulochana, N

2004-08-01

The fruit of the jack (Artocarpus heterophyllus) is one of the popular fruits in India, where the total area under this fruit is about 13,460 ha. A significant amount of peel (approximately 2,714-11,800 kg per tree per year) is discarded as agricultural waste, as apart from its use as a table fruit, it is popular in many culinary preparations. Treatment of jackfruit peel with sulphuric acid produced a carbonaceous product which was used to study its efficiency as an adsorbent for the removal of Cd(II) from aqueous solution. Batch experiments were performed as a function of process parameters; agitation time, initial metal concentration, adsorbent concentration and pH. Kinetic analyses made with Lagergren pseudo-first-order, Ritchie second-order and modified Ritchie second-order models showed better fits with modified Ritchie second-order model. The Langmuir-Freundlich (Sips equation) model best defined the experimental equilibrium data among the three isotherm models (Freundlich, Langmuir and Langmuir-Freundlich) tested. Taking a particular metal concentration, the optimum dose and pH required for the maximum metal removal was established. A complete recovery of the adsorbed metal ions from the spent adsorbent was achieved by using 0.01 M HCl.

Epoxide-functionalization of polyethyleneimine for synthesis of stable carbon dioxide adsorbent in temperature swing adsorption

PubMed Central

Choi, Woosung; Min, Kyungmin; Kim, Chaehoon; Ko, Young Soo; Jeon, Jae Wan; Seo, Hwimin; Park, Yong-Ki; Choi, Minkee

2016-01-01

Amine-containing adsorbents have been extensively investigated for post-combustion carbon dioxide capture due to their ability to chemisorb low-concentration carbon dioxide from a wet flue gas. However, earlier studies have focused primarily on the carbon dioxide uptake of adsorbents, and have not demonstrated effective adsorbent regeneration and long-term stability under such conditions. Here, we report the versatile and scalable synthesis of a functionalized-polyethyleneimine (PEI)/silica adsorbent which simultaneously exhibits a large working capacity (2.2 mmol g−1) and long-term stability in a practical temperature swing adsorption process (regeneration under 100% carbon dioxide at 120 °C), enabling the separation of concentrated carbon dioxide. We demonstrate that the functionalization of PEI with 1,2-epoxybutane reduces the heat of adsorption and facilitates carbon dioxide desorption (>99%) during regeneration compared with unmodified PEI (76%). Moreover, the functionalization significantly improves long-term adsorbent stability over repeated temperature swing adsorption cycles due to the suppression of urea formation and oxidative amine degradation. PMID:27572662

Correlation between surface morphology and surface forces of protein A adsorbed on mica.

PubMed Central

Ohnishi, S; Murata, M; Hato, M

1998-01-01

We have investigated the morphology and surface forces of protein A adsorbed on mica surface in the protein solutions of various concentrations. The force-distance curves, measured with a surface force apparatus (SFA), were interpreted in terms of two different regimens: a "large-distance" regimen in which an electrostatic double-layer force dominates, and an "adsorbed layer" regimen in which a force of steric origin dominates. To further clarify the forces of steric origin, the surface morphology of the adsorbed protein layer was investigated with an atomic force microscope (AFM) because the steric repulsive forces are strongly affected by the adsorption mode of protein A molecules on mica. At lower protein concentrations (2 ppm, 10 ppm), protein A molecules were adsorbed "side-on" parallel to the mica surfaces, forming a monolayer of approximately 2.5 nm. AFM images at higher concentrations (30 ppm, 100 ppm) showed protruding structures over the monolayer, which revealed that the adsorbed protein A molecules had one end oriented into the solution, with the remainder of each molecule adsorbed side-on to the mica surface. These extending ends of protein A overlapped each other and formed a "quasi-double layer" over the mica surface. These AFM images proved the existence of a monolayer of protein A molecules at low concentrations and a "quasi-double layer" with occasional protrusions at high concentrations, which were consistent with the adsorption mode observed in the force-distance curves. PMID:9449346

Adsorbed molecules in external fields: Effect of confining potential.

PubMed

Tyagi, Ashish; Silotia, Poonam; Maan, Anjali; Prasad, Vinod

2016-12-05

We study the rotational excitation of a molecule adsorbed on a surface. As is well known the interaction potential between the surface and the molecule can be modeled in number of ways, depending on the molecular structure and the geometry under which the molecule is being adsorbed by the surface. We explore the effect of change of confining potential on the excitation, which is largely controlled by the static electric fields and continuous wave laser fields. We focus on dipolar molecules and hence we restrict ourselves to the first order interaction in field-molecule interaction potential either through permanent dipole moment or/and the molecular polarizability parameter. It is shown that confining potential shapes, strength of the confinement, strongly affect the excitation. We compare our results for different confining potentials. Copyright © 2016 Elsevier B.V. All rights reserved.

Kondo effect in single cobalt phthalocyanine molecules adsorbed on Au(111) monoatomic steps

NASA Astrophysics Data System (ADS)

Zhao, Aidi; Hu, Zhenpeng; Wang, Bing; Xiao, Xudong; Yang, Jinlong; Hou, J. G.

2008-06-01

The Kondo effect in single dehydrogenated cobalt phthalocyanine (CoPc) molecules adsorbed on Au(111) monoatomic steps was studied with a low temperature scanning tunneling microscope. The CoPc molecules adsorbed on Au(111) monoatomic steps show two typical configurations, which can be dehydrogenated to reveal Kondo effect. Moreover, the Kondo temperatures (TK) measured for different molecules vary in a large range from ~150 to ~550 K, increasing monotonically with decreasing Co-Au distance. A simple model consisting of a single Co 3dz2 orbital and a Au 6s orbital is considered and gives a qualitative explanation to the dependence. The large variation of TK is attributed to the variation of the interaction between the magnetic-active cobalt ion and the Au substrate resulted from different Co-Au distances.

Development of a new adsorbent from agro-industrial waste and its potential use in endocrine disruptor compound removal.

PubMed

Rovani, Suzimara; Censi, Monique T; Pedrotti, Sidnei L; Lima, Eder C; Cataluña, Renato; Fernandes, Andreia N

2014-04-30

A new activated carbon (AC) material was prepared by pyrolysis of a mixture of coffee grounds, eucalyptus sawdust, calcium hydroxide and soybean oil at 800°C. This material was used as adsorbent for the removal of the endocrine disruptor compounds 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) from aqueous solutions. The carbon material was characterized by scanning electron microscopy (SEM), infrared spectroscopy (FTIR), N2 adsorption/desorption curves and point of zero charge (pHPZC). Variables including the initial pH of the adsorbate solutions, adsorbent masses and contact time were optimized. The optimum range of initial pH for removal of endocrine disruptor compounds (EDC) was 2.0-11.0. The kinetics of adsorption were investigated using general order, pseudo first-order and pseudo-second order kinetic models. The Sips isotherm model gave the best fits of the equilibrium data (298K). The maximum amounts of E2 and EE2 removed at 298K were 7.584 (E2) and 7.883mgg(-1) (EE2) using the AC as adsorbent. The carbon adsorbent was employed in SPE (solid phase extraction) of E2 and EE2 from aqueous solutions. Copyright © 2014 Elsevier B.V. All rights reserved.

Molecular Structure and Equilibrium Forces of Bovine Submaxillary Mucin Adsorbed at a Solid-Liquid Interface.

PubMed

Zappone, Bruno; Patil, Navinkumar J; Madsen, Jan B; Pakkanen, Kirsi I; Lee, Seunghwan

2015-04-21

By combining dynamic light scattering, circular dichroism spectroscopy, atomic force microscopy, and surface force apparatus, the conformation of bovine submaxillary mucin in dilute solution and nanomechanical properties of mucin layers adsorbed on mica have been investigated. The samples were prepared by additional chromatographic purification of commercially available products. The mucin molecule was found to have a z-average hydrodynamic diameter of ca. 35 nm in phosphate buffered solution, without any particular secondary or tertiary structure. The contour length of the mucin is larger than, yet of the same order of magnitude as the diameter, indicating that the molecule can be modeled as a relatively rigid polymeric chain due to the large persistence length of the central glycosylated domain. Mucin molecules adsorbed abundantly onto mica from saline buffer, generating polymer-like, long-ranged, repulsive, and nonhysteretic forces upon compression of the adsorbed layers. Detailed analysis of such forces suggests that adsorbed mucins had an elongated conformation favored by the stiffness of the central domain. Acidification of aqueous media was chosen as means to reduce mucin-mucin and mucin-substrate electrostatic interactions. The hydrodynamic diameter in solution did not significantly change when the pH was lowered, showing that the large persistence length of the mucin molecule is due to steric hindrance between sugar chains, rather than electrostatic interactions. Remarkably, the force generated by an adsorbed layer with a fixed surface coverage also remained unaltered upon acidification. This observation can be linked to the surface-protective, pH-resistant role of bovine submaxillary mucin in the variable environmental conditions of the oral cavity.

Adsorbent catalytic nanoparticles and methods of using the same

DOEpatents

Slowing, Igor Ivan; Kandel, Kapil

2017-01-31

The present invention provides an adsorbent catalytic nanoparticle including a mesoporous silica nanoparticle having at least one adsorbent functional group bound thereto. The adsorbent catalytic nanoparticle also includes at least one catalytic material. In various embodiments, the present invention provides methods of using and making the adsorbent catalytic nanoparticles. In some examples, the adsorbent catalytic nanoparticles can be used to selectively remove fatty acids from feedstocks for biodiesel, and to hydrotreat the separated fatty acids.

Adsorbed Molecules and Surface Treatment Effect on Optical Properties of ZnO Nanowires Grown by MOCVD

NASA Astrophysics Data System (ADS)

Jabri, S.; Souissi, H.; Sallet, V.; Lusson, A.; Meftah, A.; Galtier, P.; Oueslati, M.

2017-07-01

We have investigated the optical properties of ZnO nanowires grown by metalorganic chemical vapor deposition (MOCVD) with nitrous oxide (N2O) as oxygen precursor. Photoluminescence (PL) and Raman measurements showed the influence of adsorbed molecules on the optical properties. Low-temperature (4 K) PL studies on the surface exciton (SX) at 3.3660 eV elucidated the nature and origin of this emission. In particular, surface treatment by annealing at high temperature under inert gas reduced the emission intensity of SX. Raman vibrational spectra proved that presence of a considerable amount of adsorbed molecules on the surface of ZnO nanowires plays a key role in the occurrence of surface excitons.

197 Au Mössbauer study of the gold species adsorbed on carbon from cyanide solutions

NASA Astrophysics Data System (ADS)

Kongolo, K.; Bahr, A.; Friedl, J.; Wagner, F. E.

1990-04-01

The gold species present on activated carbon after adsorption from solutions of Au(CN)2 - have been studied by197Au Mössbauer spectroscopy as a function of the pH value of the solution, the loading of the carbon, the coadsorption of polyvalent cations, and the treatment of the samples after adsorption. The gold was found to be adsorbed mainly as Au(CN)2 -. Coadsorbed polyvalent cations (Ca²+, Gd³+) have no influence on the Mössbauer parameters of the adsorbed gold complex. After adsorption from acidic solutions (pH ≲ 4), one finds a substantial amount of adsorbed gold with Mössbauer parameters similar to those of crystalline AuCN. Presumably, this gold is bound in Aux(CN)x+1 oligomers which form during drying. An additional product with Mössbauer parameters close to those of KAu(CN)2Cl2 was observed on dried samples after adsorption at pH 1. A minor gold species with an uncommonly small electric quadrupole splitting was found on wet carbons but disappeared on drying.

Enhanced CO2 adsorptive performance of PEI/SBA-15 adsorbent using phosphate ester based surfactants as additives.

PubMed

Cheng, Dandan; Liu, Yue; Wang, Haiqiang; Weng, Xiaole; Wu, Zhongbiao

2015-12-01

In this study, a series of polyetherimide/SBA-15: 2-D hexagonal P6mm, Santa Barbara USA (PEI/SBA-15) adsorbents modified by phosphoric ester based surfactants (including tri(2-ethylhexyl) phosphate (TEP), bis(2-ethylhexyl) phosphate (BEP) and trimethyl phosphonoacetate (TMPA)) were prepared for CO2 adsorption. Experimental results indicated that the addition of TEP and BEP had positive effects on CO2 adsorption capacity over PEI/SBA-15. In particular, the CO2 adsorption amount could be improved by around 20% for 45PEI-5TEP/SBA-15 compared to the additive-free adsorbent. This could be attributed to the decrease of CO2 diffusion resistance in the PEI bulk network due to the interactions between TEP and loaded PEI molecules, which was further confirmed by adsorption kinetics results. In addition, it was also found that the cyclic performance of the TEP-modified adsorbent was better than the surfactant-free one. This could be due to two main reasons, based on the results of in situ DRIFT and TG-DSC tests. First and more importantly, adsorbed CO2 species could be desorbed more rapidly over TEP-modified adsorbent during the thermal desorption process. Furthermore, the enhanced thermal stability after TEP addition ensured lower degradation of amine groups during adsorption/desorption cycles. Copyright © 2015. Published by Elsevier B.V.

Removing ammonium from water and wastewater using cost-effective adsorbents: A review.

PubMed

Huang, Jianyin; Kankanamge, Nadeeka Rathnayake; Chow, Christopher; Welsh, David T; Li, Tianling; Teasdale, Peter R

2018-01-01

Ammonium is an important nutrient in primary production; however, high ammonium loads can cause eutrophication of natural waterways, contributing to undesirable changes in water quality and ecosystem structure. While ammonium pollution comes from diffuse agricultural sources, making control difficult, industrial or municipal point sources such as wastewater treatment plants also contribute significantly to overall ammonium pollution. These latter sources can be targeted more readily to control ammonium release into water systems. To assist policy makers and researchers in understanding the diversity of treatment options and the best option for their circumstance, this paper produces a comprehensive review of existing treatment options for ammonium removal with a particular focus on those technologies which offer the highest rates of removal and cost-effectiveness. Ion exchange and adsorption material methods are simple to apply, cost-effective, environmentally friendly technologies which are quite efficient at removing ammonium from treated water. The review presents a list of adsorbents from the literature, their adsorption capacities and other parameters needed for ammonium removal. Further, the preparation of adsorbents with high ammonium removal capacities and new adsorbents is discussed in the context of their relative cost, removal efficiencies, and limitations. Efficient, cost-effective, and environmental friendly adsorbents for the removal of ammonium on a large scale for commercial or water treatment plants are provided. In addition, future perspectives on removing ammonium using adsorbents are presented. Copyright © 2017. Published by Elsevier B.V.

Cutting Edge: Protection by Antiviral Memory CD8 T Cells Requires Rapidly Produced Antigen in Large Amounts.

PubMed

Remakus, Sanda; Ma, Xueying; Tang, Lingjuan; Xu, Ren-Huan; Knudson, Cory; Melo-Silva, Carolina R; Rubio, Daniel; Kuo, Yin-Ming; Andrews, Andrew; Sigal, Luis J

2018-05-15

Numerous attempts to produce antiviral vaccines by harnessing memory CD8 T cells have failed. A barrier to progress is that we do not know what makes an Ag a viable target of protective CD8 T cell memory. We found that in mice susceptible to lethal mousepox (the mouse homolog of human smallpox), a dendritic cell vaccine that induced memory CD8 T cells fully protected mice when the infecting virus produced Ag in large quantities and with rapid kinetics. Protection did not occur when the Ag was produced in low amounts, even with rapid kinetics, and protection was only partial when the Ag was produced in large quantities but with slow kinetics. Hence, the amount and timing of Ag expression appear to be key determinants of memory CD8 T cell antiviral protective immunity. These findings may have important implications for vaccine design. Copyright © 2018 by The American Association of Immunologists, Inc.

Detection of adsorbed water and hydroxyl on the Moon.

PubMed

Clark, Roger N

2009-10-23

Data from the Visual and Infrared Mapping Spectrometer (VIMS) on Cassini during its flyby of the Moon in 1999 show a broad absorption at 3 micrometers due to adsorbed water and near 2.8 micrometers attributed to hydroxyl in the sunlit surface on the Moon. The amounts of water indicated in the spectra depend on the type of mixing and the grain sizes in the rocks and soils but could be 10 to 1000 parts per million and locally higher. Water in the polar regions may be water that has migrated to the colder environments there. Trace hydroxyl is observed in the anorthositic highlands at lower latitudes.

Development of carbon dioxide adsorbent from rice husk char

NASA Astrophysics Data System (ADS)

Abang, S.; Janaun, J.; Anisuzzaman, S. M.; Ikhwan, F. S.

2016-06-01

This study was mainly concerned about the development of carbon dioxide (CO2) adsorbent from rice husk (RH). Several chemical treatments were used to produce activated rice husk char (RHAC) from RH. Initially the RH was refluxed with 3M of sodium hydroxide (NaOH) solution, activation followed by using 0.5M of zinc chloride (ZnCl2) solution and finally acidic treatment by using 0.1M of hydrochloric acid (HCl). Then, the RHAC was functionalized by using 3-chloropropylamine hydrochloride (3-CPA) and noted as RHN. RHN samples were characterized with scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), fourier transform infrared spectroscopy (FTIR). Based on the SEM, the RHN sample had a large pore diameter compared to RH sample after being treated. Based on MIP data, the average pore diameter between RH and RHAC samples were increased significantly from 0.928 microns to 1.017 microns. The RHN sample also had higher total porosity (%) compared to RHAC and RH (58.45%, 47.82% and 45.57% respectively). The total specific surface area of the sample was much increasing from RHO to RHAC (29.17 m2/g and 62.94 m2/g respectively) and slightly being decreasing from RHAC to RHN (58.88 m2/g). FTIR result showed the present of weak band at 1587 cm-1 which demonstrating of the amine group present on the sample. The CO2 capture result showed that the decreasing of operating temperature can increase the breakthrough time of CO2 capture. On the contrary decreasing of CO2 gas flow rate can increase the breakthrough time of CO2 capture. The highest total amount of CO2 adsorbed was 25338.57 mg of CO2/g of RHN sample by using 100 mL/min of gas flow rate at 30oC. Based on adsorption isotherm analysis, the Freundlich isotherm was the best isotherm to describe the CO2 adsorption on the sample.

Allantoin as a solid phase adsorbent for removing endotoxins.

PubMed

Vagenende, Vincent; Ching, Tim-Jang; Chua, Rui-Jing; Gagnon, Pete

2013-10-04

In this study we present a simple and robust method for removing endotoxins from protein solutions by using crystals of the small-molecule compound 2,5-dioxo-4-imidazolidinyl urea (allantoin) as a solid phase adsorbent. Allantoin crystalline powder is added to a protein solution at supersaturated concentrations, endotoxins bind and undissolved allantoin crystals with bound endotoxins are removed by filtration or centrifugation. This method removes an average of 99.98% endotoxin for 20 test proteins. The average protein recovery is ∼80%. Endotoxin binding is largely independent of pH, conductivity, reducing agent and various organic solvents. This is consistent with a hydrogen-bond based binding mechanism. Allantoin does not affect protein activity and stability, and the use of allantoin as a solid phase adsorbent provides better endotoxin removal than anion exchange, polymixin affinity and biological affinity methods for endotoxin clearance. Copyright © 2013 Elsevier B.V. All rights reserved.

Investigations Into the Reusability of Amidoxime-Based Polymeric Uranium Adsorbents

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

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

Significant advancements in amidoxime-based polymeric adsorbents to extract uranium from seawater are achieved in recent years. The success of uranium adsorbent development can help provide a sustainable supply of fuel for nuclear reactors. To bring down the production cost of this new technology, in addition to the development of novel adsorbents with high uranium capacity and manufacture cost, the development of adsorbent re-using technique is critical because it can further reduce the cost of the adsorbent manufacture. In our last report, the use of high concentrations of bicarbonate solution (3M KHCO3) was identified as a cost-effective, environmental friendly method tomore » strip uranium from amidoxime-based polymeric adsorbents. This study aims to further improve the method for high recovery of uranium capacity in re-uses and to evaluate the performance of adsorbents after multiple re-use cycles. Adsorption of dissolved organic matter (DOM) on the uranium adsorbents during seawater exposure can hinder the uranium adsorption and slow down the adsorption rate. An additional NaOH rinse (0.5 M NaOH, room temperature) was applied after the 3 M KHCO3 elution to remove natural organic matter from adsorbents. The combination of 3 M KHCO3 elution and 0.5 M NaOH rinse significantly improves the recovery of uranium adsorption capacity in the re-used adsorbents. In the first re-use, most ORNL adsorbents tested achieve ~100% recovery by using 3 M KHCO3 elution + 0.5 M NaOH rinse approach, in comparison to 54% recovery when only 3 M KHCO3 elution was applied. A significant drop in capacity was observed when the adsorbents went through more than one re-use. FTIR spectra revealed that degradation of amidoxime ligands occurs during seawater exposure, and is more significant the longer the exposure time. Significantly elevated ratios of Ca/U and Mg/U in re-used adsorbents support the decrease in abundance of amidoxime ligands and increase carboxylate group from FT

Binary chromatographic data and estimation of adsorbent porosities. [data for system n-heptane/n-pentane

NASA Technical Reports Server (NTRS)

Meisch, A. J.

1972-01-01

Data for the system n-pentane/n-heptane on porous Chromosorb-102 adsorbent were obtained at 150, 175, and 200 C for mixtures containing zero to 100% n-pentane by weight. Prior results showing limitations on superposition of pure component data to predict multicomponent chromatograms were verified. The thermodynamic parameter MR0 was found to be a linear function of sample composition. A nonporous adsorbent failed to separate the system because of large input sample dispersions. A proposed automated data processing scheme involving magnetic tape recording of the detector signals and processing by a minicomputer was rejected because of resolution limitations of the available a/d converters. Preliminary data on porosity and pore size distributions of the adsorbents were obtained.

A potential low cost adsorbent for the removal of cationic dyes from aqueous solutions

NASA Astrophysics Data System (ADS)

Uddin, Md. Tamez; Rahman, Md. Arifur; Rukanuzzaman, Md.; Islam, Md. Akhtarul

2017-10-01

This study was aimed at using mango leaf powder (MLP) as a potential adsorbent for the removal of methylene blue (MB) from aqueous solutions. Characterization of the adsorbent was carried out with scanning electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption-desorption analysis. The pH at the point of zero charge of the adsorbent was determined by titration method and was found a value to be 5.6 ± 0.2. Batch studies were performed to evaluate the influence of various experimental parameters like initial solution pH, contact time, initial concentration of dye and adsorbent dosage on the removal of MB. An adsorption-desorption study was carried out resulting the mechanism of adsorption was carried out by electrostatic force of attraction. The adsorption equilibrium time required for the adsorption of MB on MLP was almost 2 h and 85 ± 5% of the total amount of dye uptake was found to occur in the first rapid phase (30 min). The Langmuir and Freundlich isotherm models were used for modeling the adsorption equilibrium. The experimental equilibrium data could be well interpreted by Langmuir isotherm with maximum adsorption capacity of 156 mg/g. To state the sorption kinetics, the fits of pseudo-first-order and pseudo-second-order kinetic models were investigated. It was obtained that the adsorption process followed the pseudo-second-order rate kinetics. The above findings suggest that MLP can be effectively used for decontamination of dye containing wastewater.

Evaluation of Adsorbed Arsenic and Potential Contribution to Shallow Groundwater in Tulare Lake Bed Area, Tulare Basin, California

USGS Publications Warehouse

Gao, S.; Fujii, R.; Chalmers, A.T.; Tanji, K.K.

2004-01-01

Elevated As concentrations in shallow groundwater in parts of the Tulare Basin, California, are a concern because of potential migration into deeper aquifers that could serve as a source of future drinking water. The objectives of this study were to evaluate adsorbed As and the potential contribution to groundwater using (i) isotopic dilution, (ii) successive extraction with an electrolyte solution resembling the pore-water chemical composition, and (iii) PO4 exchange for As. Sediment samples collected from 2 to 4 m below land surface in the Tulare Lake bed area contained a total As concentration of 24 mg As kg-1. Pore water extracted under hydraulic pressure contained a total As concentration of 590 ??g As L-1, which predominantly contained As as arsenate [As(V), 97%], a minor amount of arsenite [As(III), 3%], and non-detectable organic As. The isotopic dilution method [73As(V)] estimated that the concentration of adsorbed As(V) on the sediment was 5.7 mg As kg-1 at pH 8.5 and 6.7 mg As kg-1 at pH 7.5, respectively. Fourteen successive 24-h extractions with the artificial pore water released up to 57 to 61% of the adsorbed As(V) that was determined by isotopic dilution, indicating that only a portion of the adsorbed As could be released to groundwater. The phosphate-exchangeable As (0.1 M PO4, pH 8.5 or 7.5) was 63% of the isotopically exchangeable As(V). Thus, extraction of As by 0.1 M PO4 at ambient pHs is recommended as a method to determine the potential amount of As(V) on sediments that could be released to the solution phase. The overall results indicated that adsorbed As could be a significant source of As to groundwater. However, other factors that affect As transport such as the leaching rate need to be considered.

A Reliable Hybrid Adsorbent for Efficient Radioactive Cesium Accumulation from Contaminated Wastewater

PubMed Central

Awual, Md. Rabiul; Yaita, Tsuyoshi; Miyazaki, Yuji; Matsumura, Daiju; Shiwaku, Hideaki; Taguchi, Tomitsugu

2016-01-01

Cesium (Cs) removal from nuclear liquid wastewater has become an emerging issue for safeguarding public health after the accident at the Fukushima Daiichi Nuclear Power Plant. A novel macrocyclic ligand of o-benzo-p-xylyl-22-crown-6-ether (OBPX22C6) was developed and successfully immobilized onto mesoporous silica for the preparation of hybrid adsorbent. The benzene ring π electron is the part of crown ether of OBPX22C6 for easy orientation of the macrocyclic compound for making the π electron donation with Cs complexation. The potential and feasibility of the hybrid adsorbent as being Cs selective was evaluated in terms of sensitivity, selectivity and reusability. The results clarified that the Cs removal process was rapid and reached saturation within a short time. Considering the effect of competitive ions, sodium (Na) did not markedly affect the Cs adsorption whereas potassium (K) was slightly affected due to the similar ionic radii. However, the oxygen in long ethylene glycol chain in OBPX22C6 was expected to show strong coordination, including Cs-π interaction with Cs even in the presence of the high amount of K and Na. Due to its high selectivity and reusability, significant volume reduction is expected as this promising hybrid adsorbent is used for Cs removal in Fukushima wastewater. PMID:26818070

A Reliable Hybrid Adsorbent for Efficient Radioactive Cesium Accumulation from Contaminated Wastewater.

PubMed

Awual, Md Rabiul; Yaita, Tsuyoshi; Miyazaki, Yuji; Matsumura, Daiju; Shiwaku, Hideaki; Taguchi, Tomitsugu

2016-01-28

Cesium (Cs) removal from nuclear liquid wastewater has become an emerging issue for safeguarding public health after the accident at the Fukushima Daiichi Nuclear Power Plant. A novel macrocyclic ligand of o-benzo-p-xylyl-22-crown-6-ether (OBPX22C6) was developed and successfully immobilized onto mesoporous silica for the preparation of hybrid adsorbent. The benzene ring π electron is the part of crown ether of OBPX22C6 for easy orientation of the macrocyclic compound for making the π electron donation with Cs complexation. The potential and feasibility of the hybrid adsorbent as being Cs selective was evaluated in terms of sensitivity, selectivity and reusability. The results clarified that the Cs removal process was rapid and reached saturation within a short time. Considering the effect of competitive ions, sodium (Na) did not markedly affect the Cs adsorption whereas potassium (K) was slightly affected due to the similar ionic radii. However, the oxygen in long ethylene glycol chain in OBPX22C6 was expected to show strong coordination, including Cs-π interaction with Cs even in the presence of the high amount of K and Na. Due to its high selectivity and reusability, significant volume reduction is expected as this promising hybrid adsorbent is used for Cs removal in Fukushima wastewater.

Geo-reCAPTCHA: Crowdsourcing large amounts of geographic information from earth observation data

NASA Astrophysics Data System (ADS)

Hillen, Florian; Höfle, Bernhard

2015-08-01

The reCAPTCHA concept provides a large amount of valuable information for various applications. First, it provides security, e.g., for a form on a website, by means of a test that only a human could solve. Second, the effort of the user for this test is used to generate additional information, e.g., digitization of books or identification of house numbers. In this work, we present a concept for adapting the reCAPTCHA idea to create user-generated geographic information from earth observation data, and the requirements during the conception and implementation are depicted in detail. Furthermore, the essential parts of a Geo-reCAPTCHA system are described, and afterwards transferred, to a prototype implementation. An empirical user study is conducted to investigate the Geo-reCAPTCHA approach, assessing time and quality of the resulting geographic information. Our results show that a Geo-reCAPTCHA can be solved by the users of our study on building digitization in a short amount of time (19.2 s on average) with an overall average accuracy of the digitizations of 82.2%. In conclusion, Geo-reCAPTCHA has the potential to be a reasonable alternative to the typical reCAPTCHA, and to become a new data-rich channel of crowdsourced geographic information.

Antibody recognition of the glycoprotein g of viral haemorrhagic septicemia virus (VHSV) purified in large amounts from insect larvae

PubMed Central

2011-01-01

Background There are currently no purification methods capable of producing the large amounts of fish rhabdoviral glycoprotein G (gpG) required for diagnosis and immunisation purposes or for studying structure and molecular mechanisms of action of this molecule (ie. pH-dependent membrane fusion). As a result of the unavailability of large amounts of the gpG from viral haemorrhagic septicaemia rhabdovirus (VHSV), one of the most dangerous viruses affecting cultured salmonid species, research interests in this field are severely hampered. Previous purification methods to obtain recombinant gpG from VHSV in E. coli, yeast and baculovirus grown in insect cells have not produced soluble conformations or acceptable yields. The development of large-scale purification methods for gpGs will also further research into other fish rhabdoviruses, such as infectious haematopoietic necrosis virus (IHNV), spring carp viremia virus (SVCV), hirame rhabdovirus (HIRRV) and snakehead rhabdovirus (SHRV). Findings Here we designed a method to produce milligram amounts of soluble VHSV gpG. Only the transmembrane and carboxy terminal-deleted (amino acid 21 to 465) gpG was efficiently expressed in insect larvae. Recognition of G21-465 by ß-mercaptoethanol-dependent neutralizing monoclonal antibodies (N-MAbs) and pH-dependent recognition by sera from VHSV-hyperimmunized or VHSV-infected rainbow trout (Oncorhynchus mykiss) was demonstrated. Conclusions Given that the purified G21-465 conserved some of its most important properties, this method might be suitable for the large-scale production of fish rhabdoviral gpGs for use in diagnosis, fusion and antigenicity studies. PMID:21693048

Antibody recognition of the glycoprotein g of viral haemorrhagic septicemia virus (VHSV) purified in large amounts from insect larvae.

PubMed

Encinas, Paloma; Gomez-Sebastian, Silvia; Nunez, Maria Carmen; Gomez-Casado, Eduardo; Escribano, Jose M; Estepa, Amparo; Coll, Julio

2011-06-21

There are currently no purification methods capable of producing the large amounts of fish rhabdoviral glycoprotein G (gpG) required for diagnosis and immunisation purposes or for studying structure and molecular mechanisms of action of this molecule (ie. pH-dependent membrane fusion). As a result of the unavailability of large amounts of the gpG from viral haemorrhagic septicaemia rhabdovirus (VHSV), one of the most dangerous viruses affecting cultured salmonid species, research interests in this field are severely hampered. Previous purification methods to obtain recombinant gpG from VHSV in E. coli, yeast and baculovirus grown in insect cells have not produced soluble conformations or acceptable yields. The development of large-scale purification methods for gpGs will also further research into other fish rhabdoviruses, such as infectious haematopoietic necrosis virus (IHNV), spring carp viremia virus (SVCV), hirame rhabdovirus (HIRRV) and snakehead rhabdovirus (SHRV). Here we designed a method to produce milligram amounts of soluble VHSV gpG. Only the transmembrane and carboxy terminal-deleted (amino acid 21 to 465) gpG was efficiently expressed in insect larvae. Recognition of G21-465 by ß-mercaptoethanol-dependent neutralizing monoclonal antibodies (N-MAbs) and pH-dependent recognition by sera from VHSV-hyperimmunized or VHSV-infected rainbow trout (Oncorhynchus mykiss) was demonstrated. Given that the purified G21-465 conserved some of its most important properties, this method might be suitable for the large-scale production of fish rhabdoviral gpGs for use in diagnosis, fusion and antigenicity studies.

Nanofiber adsorbents for high productivity downstream processing.

PubMed

Hardick, Oliver; Dods, Stewart; Stevens, Bob; Bracewell, Daniel G

2013-04-01

Electrospun polymeric nanofiber adsorbents offer an alternative ligand support surface for bioseparations. Their non-woven fiber structure with diameters in the sub-micron range creates a remarkably high surface area. To improve the purification productivity of biological molecules by chromatography, cellulose nanofiber adsorbents were fabricated and assembled into a cartridge and filter holder format with a volume of 0.15 mL, a bed height of 0.3 mm and diameter of 25 mm. The present study investigated the performance of diethylaminoethyl (DEAE) derivatized regenerated cellulose nanofiber adsorbents based on criteria including mass transfer and flow properties, binding capacity, and fouling effects. Our results show that nanofibers offer higher flow and mass transfer properties. The non-optimized DEAE-nanofiber adsorbents indicate a binding capacity of 10% that of packed bed systems with BSA as a single component system. However, they operate reproducibly at flowrates of a hundred times that of packed beds, resulting in a potential productivity increase of 10-fold. Lifetime studies showed that this novel adsorbent material operated reproducibly with complex feed material (centrifuged and 0.45 µm filtered yeast homogenate) and harsh cleaning-in-place conditions over multiple cycles. DEAE nanofibers showed superior operating performance in permeability and fouling over conventional adsorbents indicating their potential for bioseparation applications. Copyright © 2012 Wiley Periodicals, Inc.

Highly Sensitive GMO Detection Using Real-Time PCR with a Large Amount of DNA Template: Single-Laboratory Validation.

PubMed

Mano, Junichi; Hatano, Shuko; Nagatomi, Yasuaki; Futo, Satoshi; Takabatake, Reona; Kitta, Kazumi

2018-03-01

Current genetically modified organism (GMO) detection methods allow for sensitive detection. However, a further increase in sensitivity will enable more efficient testing for large grain samples and reliable testing for processed foods. In this study, we investigated real-time PCR-based GMO detection methods using a large amount of DNA template. We selected target sequences that are commonly introduced into many kinds of GM crops, i.e., 35S promoter and nopaline synthase (NOS) terminator. This makes the newly developed method applicable to a wide range of GMOs, including some unauthorized ones. The estimated LOD of the new method was 0.005% of GM maize events; to the best of our knowledge, this method is the most sensitive among the GM maize detection methods for which the LOD was evaluated in terms of GMO content. A 10-fold increase in the DNA amount as compared with the amount used under common testing conditions gave an approximately 10-fold reduction in the LOD without PCR inhibition. Our method is applicable to various analytical samples, including processed foods. The use of other primers and fluorescence probes would permit highly sensitive detection of various recombinant DNA sequences besides the 35S promoter and NOS terminator.

Chitin Adsorbents for Toxic Metals: A Review

PubMed Central

Anastopoulos, Ioannis; Bhatnagar, Amit; Bikiaris, Dimitrios N.; Kyzas, George Z.

2017-01-01

Wastewater treatment is still a critical issue all over the world. Among examined methods for the decontamination of wastewaters, adsorption is a promising, cheap, environmentally friendly and efficient procedure. There are various types of adsorbents that have been used to remove different pollutants such as agricultural waste, compost, nanomaterials, algae, etc., Chitin (poly-β-(1,4)-N-acetyl-d-glucosamine) is the second most abundant natural biopolymer and it has attracted scientific attention as an inexpensive adsorbent for toxic metals. This review article provides information about the use of chitin as an adsorbent. A list of chitin adsorbents with maximum adsorption capacity and the best isotherm and kinetic fitting models are provided. Moreover, thermodynamic studies, regeneration studies, the mechanism of adsorption and the experimental conditions are also discussed in depth. PMID:28067848

Recovery of iron oxides from acid mine drainage and their application as adsorbent or catalyst.

PubMed

Flores, Rubia Gomes; Andersen, Silvia Layara Floriani; Maia, Leonardo Kenji Komay; José, Humberto Jorge; Moreira, Regina de Fatima Peralta Muniz

2012-11-30

Iron oxide particles recovered from acid mine drainage represent a potential low-cost feedstock to replace reagent-grade chemicals in the production of goethite, ferrihydrite or magnetite with relatively high purity. Also, the properties of iron oxides recovered from acid mine drainage mean that they can be exploited as catalysts and/or adsorbents to remove azo dyes from aqueous solutions. The main aim of this study was to recover iron oxides with relatively high purity from acid mine drainage to act as a catalyst in the oxidation of dye through a Fenton-like mechanism or as an adsorbent to remove dyes from an aqueous solution. Iron oxides (goethite) were recovered from acid mine drainage through a sequential precipitation method. Thermal treatment at temperatures higher than 300 °C produces hematite through a decrease in the BET area and an increase in the point of zero charge. In the absence of hydrogen peroxide, the solids adsorbed the textile dye Procion Red H-E7B according to the Langmuir model, and the maximum amount adsorbed decreased as the temperature of the thermal treatment increased. The decomposition kinetics of hydrogen peroxide is dependent on the H(2)O(2) concentration and iron oxides dosage, but the second-order rate constant normalized to the BET surface area is similar to that for different iron oxides tested in this and others studies. These results indicate that acid mine drainage could be used as a source material for the production of iron oxide catalysts/adsorbents, with comparable quality to those produced using analytical-grade reagents. Copyright © 2012 Elsevier Ltd. All rights reserved.

Methane Recovery from Gaseous Mixtures Using Carbonaceous Adsorbents

NASA Astrophysics Data System (ADS)

Buczek, Bronisław

2016-06-01

Methane recovery from gaseous mixtures has both economical and ecological aspect. Methane from different waste gases like mine gases, nitrogenated natural gases and biogases can be treated as local source for production electric and heat energy. Also occurs the problem of atmosphere pollution with methane that shows over 20 times more harmful environmental effect in comparison to carbon dioxide. One of the ways utilisation such gases is enrichment of methane in the PSA technique, which requires appropriate adsorbents. Active carbons and carbon molecular sieve produced by industry and obtained in laboratory scale were examined as adsorbent for methane recuperation. Porous structure of adsorbents was investigated using densimetry measurements and adsorption of argon at 77.5K. On the basis of adsorption data, the Dubinin-Radushkevich equation parameters, micropore volume (Wo) and characteristics of energy adsorption (Eo) as well as area micropores (Smi) and BET area (SBET) were determined. The usability of adsorbents in enrichment of the methane was evaluated in the test, which simulate the basic stages of PSA process: a) adsorbent degassing, b) pressure raise in column by feed gas, c) cocurrent desorption with analysis of out flowing gas. The composition of gas phase was accepted as the criterion of the suitability of adsorbent for methane separation from gaseous mixtures. The relationship between methane recovery from gas mixture and texture parameters of adsorbents was found.

Utility of adsorbents in the purification of drinking water: a review of characterization, efficiency and safety evaluation of various adsorbents.

PubMed

Dubey, Shashi Prabha; Gopal, Krishna; Bersillon, J L

2009-05-01

Clean drinking water is one of the implicit requisites fora healthy human population. However the growing industrialization and extensive use of chemicals for various concerns, has increased the burden of unwanted pollutants in the drinking water of developing countries like India. The entry of potentially hazardous substances into the biota has been magnifying day by day. In the absence of a possible stoppage of these, otherwise, useful chemicals, the only way to maintain safer water bodies is to develop efficient purifying technologies. One such immensely beneficial procedure that has been in use is that of purification of water using 'adsorbents'. Indigenous minerals and natural plants products have potential for removing many pollutants viz. fluoride, arsenic, nitrate, heavy metals, pesticides as well as trihalomethanes. Adsorbents which are derived from carbon, alumina, zeolite, clay minerals, iron ores, industrial by products, and natural products viz. parts of the plants, herbs and algal biomass offer promising potential of removal. In the recent years attention has been paid to develop process involving screening/pretreatment/activation/impregnation using alkalies, acids, alum, lime, manganese dioxide, ferric chloride and other chemicals which are found to enhance their adsorbing efficiency. Chemical characterization of these adsorbents recapitulates the mechanism of the process. It is imperative to observe that capacities of the adsorbents may vary depending on the characteristics, chemical modifications and concentration of the individual adsorbent. Removal kinetics is found to be based on the experimental conditions viz. pH, concentration of the adsorbate, quantity of the adsorbent and temperature. It is suggested that isotherm model is suitable tool to assess the adsorption capacities in batch and column modes. Safety evaluation and risk assessment of the process/products may be useful to provide guidelines for its sustainable disposal.

Amounts and activity concentrations of radioactive wastes from the cleanup of large areas contaminated in nuclear accidents

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

Lehto, J.; Ikaeheimonen, T.K.; Salbu, B.

The fallout from a major nuclear accident at a nuclear plant may result in a wide-scale contamination of the environment. Cleanup of contaminated areas is of special importance if these areas are populated or cultivated. All cleanup measures generate high amounts of radioactive waste, which have to be treated and disposed of in a safe manner. Scenarios assessing the amounts and activity concentrations of radioactive wastes for various cleanup measures after severe nuclear accidents have been worked out for urban, forest and agricultural areas. These scenarios are based on contamination levels and ares of contaminated lands from a model accident,more » which simulates a worst case accident at a nuclear power plant. Amounts and activity concentrations of cleanup wastes are not only dependent on the contamination levels and areas of affected lands, but also on the type of deposition, wet or dry, on the time between the deposition and the cleanup work, on the season, at which the deposition took place, and finally on the level of cleanup work. In this study practically all types of cleanup wastes were considered, whether or not the corresponding cleanup measures are cost-effective or justified. All cleanup measures are shown to create large amounts of radioactive wastes, but the amounts, as well as the activity concentrations vary widely from case to case.« less

Novel adhesive properties of poly(ethylene-oxide) adsorbed nanolayers

NASA Astrophysics Data System (ADS)

Zeng, Wenduo

Solid-polymer interfaces play crucial roles in the multidisciplinary field of nanotechnology and are the confluence of physics, chemistry, biology, and engineering. There is now growing evidence that polymer chains irreversibly adsorb even onto weakly attractive solid surfaces, forming a nanometer-thick adsorbed polymer layer ("adsorbed polymer nanolayers"). It has also been reported that the adsorbed layers greatly impact on local structures and properties of supported polymer thin films. In this thesis, I aim to clarify adhesive and tribological properties of adsorbed poly(ethylene-oxide) (PEO) nanolayers onto silicon (Si) substrates, which remain unsolved so far. The adsorbed nanolayers were prepared by the established protocol: one has to equilibrate the melt or dense solution against a solid surface; the unadsorbed chains can be then removed by a good solvent, while the adsorbed chains are assumed to maintain the same conformation due to the irreversible freezing through many physical solid-segment contacts. I firstly characterized the formation process and the surface/film structures of the adsorbed nanolayers by using X-ray reflectivity, grazing incidence X-ray diffraction, and atomic force microscopy. Secondly, to compare the surface energy of the adsorbed layers with the bulk, static contact angle measurements with two liquids (water and glycerol) were carried out using a optical contact angle meter equipped with a video camera. Thirdly, I designed and constructed a custom-built adhesion-testing device to quantify the adhesive property. The experimental results provide new insight into the microscopic structure - macroscopic property relationship at the solid-polymer interface.

Flow boundary conditions for chain-end adsorbing polymer blends.

PubMed

Zhou, Xin; Andrienko, Denis; Delle Site, Luigi; Kremer, Kurt

2005-09-08

Using the phenol-terminated polycarbonate blend as an example, we demonstrate that the hydrodynamic boundary conditions for a flow of an adsorbing polymer melt are extremely sensitive to the structure of the epitaxial layer. Under shear, the adsorbed parts (chain ends) of the polymer melt move along the equipotential lines of the surface potential whereas the adsorbed additives serve as the surface defects. In response to the increase of the number of the adsorbed additives the surface layer becomes thinner and solidifies. This results in a gradual transition from the slip to the no-slip boundary condition for the melt flow, with a nonmonotonic dependence of the slip length on the surface concentration of the adsorbed ends.

Nano-sized Adsorbate Structure Formation in Anisotropic Multilayer System

NASA Astrophysics Data System (ADS)

Kharchenko, Vasyl O.; Kharchenko, Dmitrii O.; Yanovsky, Vladimir V.

2017-05-01

In this article, we study dynamics of adsorbate island formation in a model plasma-condensate system numerically. We derive the generalized reaction-diffusion model for adsorptive multilayer system by taking into account anisotropy in transfer of adatoms between neighbor layers induced by electric field. It will be found that with an increase in the electric field strength, a structural transformation from nano-holes inside adsorbate matrix toward separated nano-sized adsorbate islands on a substrate is realized. Dynamics of adsorbate island sizes and corresponding distributions are analyzed in detail. This study provides an insight into details of self-organization of adatoms into nano-sized adsorbate islands in anisotropic multilayer plasma-condensate systems.

EVALUATION OF SOLID ADSORBENTS FOR THE COLLECTION AND ANALYSES OF AMBIENT BIOGENIC VOLATILE ORGANICS

EPA Science Inventory

Micrometeorological flux measurements of biogenic volatile organic compounds (BVOCs) usually require that large volumes of air be collected (whole air samples) or focused during the sampling process (cryogenic trapping or gas-solid partitioning on adsorbents) in order to achiev...

Mobilization of arsenite by dissimilatory reduction of adsorbed arsenate

USGS Publications Warehouse

Zobrist, J.; Dowdle, P.R.; Davis, J.A.; Oremland, R.S.

2000-01-01

Sulfurospirillum barnesii is capable of anaerobic growth using ferric iron or arsenate as electron acceptors. Cell suspensions of S. barnesii were able to reduce arsenate to arsenite when the former oxyanion was dissolved in solution, or when it was adsorbed onto the surface of ferrihydrite, a common soil mineral, by a variety of mechanisms (e.g., coprecipitation, presorption). Reduction of Fe(III) in ferrihydrite to soluble Fe(II) also occurred, but dissolution of ferrihydrite was not required in order for adsorbed arsenate reduction to be achieved. This was illustrated by bacterial reduction of arsenate coprecipitated with aluminum hydroxide, a mineral that does not undergo reductive dissolution. The rate of arsenate reduction was influenced by the method in which arsenate became associated with the mineral phases and may have been strongly coupled with arsenate desorption rates. The extent of release of arsenite into solution was governed by adsorption of arsenite onto the ferrihydrite or alumina phases. The results of these experiments have interpretive significance to the mobilization of arsenic in large alluvial aquifers, such as those of the Ganges in India and Bangladesh, and in the hyporheic zones of contaminated streams.Sulfurospirillum barnesii is capable of anaerobic growth using ferric iron or arsenate as electron acceptors. Cell suspensions of S. barnesii were able to reduce arsenate to arsenite when the former oxyanion was dissolved in solution, or when it was adsorbed onto the surface of ferrihydrite a common soil mineral, by a variety of mechanisms (e.g., coprecipitation, presorption). Reduction of Fe(III) in ferrihydrite to soluble Fe(II) also occurred, but dissolution of ferrihydrite was not required in order for adsorbed arsenate reduction to be achieved. This was illustrated by bacterial reduction of arsenate coprecipitated with aluminum hydroxide, a mineral that does not undergo reductive dissolution. The rate of arsenate reduction was

Activity, conformation and dynamics of cutinase adsorbed on poly(methyl methacrylate) latex particles.

PubMed

Baptista, R P; Santos, A M; Fedorov, A; Martinho, J M G; Pichot, C; Elaïssari, A; Cabral, J M S; Taipa, M A

2003-05-08

The adsorption of a recombinant cutinase from Fusarium solani pisi onto the surface of 100 nm diameter poly(methyl methacrylate) (PMMA) latex particles was evaluated. Adsorption of cutinase is a fast process since more than 70% of protein molecules are adsorbed onto PMMA at time zero of experiment, irrespective of the tested conditions. A Langmuir-type model fitted both protein and enzyme activity isotherms at 25 degrees C. Gamma(max) increased from 1.1 to 1.7 mg m(-2) and U(max) increased from 365 to 982 U m(-2) as the pH was raised from 4.5 to 9.2, respectively. A decrease (up to 50%) in specific activity retention was observed at acidic pH values (pH 4.5 and 5.2) while almost no inactivation (eta(act) congruent with 87-94%) was detected upon adsorption at pH 7.0 and 9.2. Concomitantly, far-UV circular dichroism (CD) spectra evidenced a reduction in the alpha-helical content of adsorbed protein at acidic pH values while at neutral and alkaline pH the secondary structure of adsorbed cutinase was similar to that of native protein. Fluorescence anisotropy decays showed the release of some constraints to the local motion of the Trp69 upon protein adsorption at pH 8.0, probably due to the disruption of the tryptophan-alanine hydrogen bond when the tryptophan interacts with the PMMA surface. Structural data associated with activity measurements at pH 7.0 and 9.2 showed that cutinase adsorbs onto PMMA particles in an end-on orientation with active site exposed to solvent and full integrity of cutinase secondary structure. Hydrophobic interactions are likely the major contribution to the adsorption mechanism at neutral and alkaline pH values, and a higher amount of protein is adsorbed to PMMA particles with increasing temperature at pH 9.2. The maximum adsorption increased from 88 to 140 mg cutinase per g PMMA with temperature raising from 25 to 50 degrees C, at pH 9.2.

Combination of rice husk and coconut shell activated adsorbent to adsorb Pb(II) ionic metal and it’s analysis using solid-phase spectrophotometry (sps)

NASA Astrophysics Data System (ADS)

Rohmah, D. N.; Saputro, S.; Masykuri, M.; Mahardiani, L.

2018-03-01

The purpose of this research was to know the effect and determine the mass comparation which most effective combination between rice husk and coconut shell activated adsorbent to adsorb Pb (II) ion using SPS method. This research used experimental method. Technique to collecting this datas of this research is carried out by several stages, which are: (1) carbonization of rice husk and coconut shell adsorbent using muffle furnace at a temperature of 350°C for an hour; (2) activation of the rice husk and coconut shell adsorbent using NaOH 1N and ZnCl2 15% activator; (3) contacting the adsorbent of rice husk and coconut shell activated adsorbent with liquid waste simulation of Pb(II) using variation comparison of rice husk and coconut shell, 1:0; 0:1; 1:1; 2:1; 1:2; (4) analysis of Pb(II) using Solid-Phase Spectrophotometry (SPS); (5) characterization of combination rice husk and coconut shell activated adsorbent using FTIR. The result of this research show that the combined effect of combination rice husk and coconut shell activated adsorbent can increase the ability of the adsorbent to absorb Pb(II) ion then the optimum adsorbent mass ratio required for absorbing 20 mL of Pb(II) ion with a concentration of 49.99 µg/L is a ratio of 2:1 with the absorption level of 97,06%Solid-Phase Spectrophotometry (SPS) is an effective method in the level of µg/L, be marked with the Limit of Detection (LOD) of 0.03 µg/L.

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.

Treatment of wastewater containing a large amount of suspended solids by a novel multi-staged UASB reactor.

PubMed

Uemura, S; Harada, H; Ohashi, A; Torimura, S

2005-12-01

Treatment of artificial wastewater containing a large amount of suspended solids comprised of soybean processing waste and pig fodder was studied using a novel multi-staged upflow anaerobic sludge blanket reactor. The reactor consisted of three compartments, each containing a gas solid separator. The wastewater had chemical oxygen demand of approximately 21600 mg l(-1), suspended solids of 12800 mg l(-1), and an ammonia concentration of 945 mg l(-1). A continuous experiment without effluent circulation showed that the multi-staged reactor was not that effective for the treatment of wastewater containing a large amount of suspended solids. However, operation of the reactor with circulation of effluent enabled the reactor to achieve organic removal of 85% and approximately 70% methane conversion at loading rates of between 4.0 to 5.4 kg-chemical oxygen demand per cubic meter per day, meaning that the reactor was more effective when effluent was circulated. Morphological investigation revealed that the crude fiber in the sludge was partially degraded and that it had many small depressions on its surface. Evolved biogas may have become caught in these depressions of the fibers and caused washout of the sludge.

Carbon dioxide pressure swing adsorption process using modified alumina adsorbents

DOEpatents

Gaffney, Thomas Richard; Golden, Timothy Christopher; Mayorga, Steven Gerard; Brzozowski, Jeffrey Richard; Taylor, Fred William

1999-01-01

A pressure swing adsorption process for absorbing CO.sub.2 from a gaseous mixture containing CO.sub.2 comprising introducing the gaseous mixture at a first pressure into a reactor containing a modified alumina adsorbent maintained at a temperature ranging from 100.degree. C. and 500.degree. C. to adsorb CO.sub.2 to provide a CO.sub.2 laden alumina adsorbent and a CO.sub.2 depleted gaseous mixture and contacting the CO.sub.2 laden adsorbent with a weakly adsorbing purge fluid at a second pressure which is lower than the first pressure to desorb CO.sub.2 from the CO.sub.2 laden alumina adsorbent. The modified alumina adsorbent which is formed by depositing a solution having a pH of 3.0 or more onto alumina and heating the alumina to a temperature ranging from 100.degree. C. and 600.degree. C., is not degraded by high concentrations of water under process operating conditions.

Carbon dioxide pressure swing adsorption process using modified alumina adsorbents

DOEpatents

Gaffney, T.R.; Golden, T.C.; Mayorga, S.G.; Brzozowski, J.R.; Taylor, F.W.

1999-06-29

A pressure swing adsorption process for absorbing CO[sub 2] from a gaseous mixture containing CO[sub 2] comprises introducing the gaseous mixture at a first pressure into a reactor containing a modified alumina adsorbent maintained at a temperature ranging from 100 C and 500 C to adsorb CO[sub 2] to provide a CO[sub 2] laden alumina adsorbent and a CO[sub 2] depleted gaseous mixture and contacting the CO[sub 2] laden adsorbent with a weakly adsorbing purge fluid at a second pressure which is lower than the first pressure to desorb CO[sub 2] from the CO[sub 2] laden alumina adsorbent. The modified alumina adsorbent which is formed by depositing a solution having a pH of 3.0 or more onto alumina and heating the alumina to a temperature ranging from 100 C and 600 C, is not degraded by high concentrations of water under process operating conditions. 1 fig.

Activated carbon prepared from coffee pulp: potential adsorbent of organic contaminants in aqueous solution.

PubMed

Gonçalves, Maraisa; Guerreiro, Mário César; Ramos, Paulize Honorato; de Oliveira, Luiz Carlos Alves; Sapag, Karim

2013-01-01

The processing of coffee beans generates large amounts of solid and liquid residues. The solid residues (pulp, husk and parchment) represent a serious environmental problem and do not have an adequate disposal mechanism. In this work, activated carbons (ACs) for adsorption of organic compounds were prepared from coffee pulp by controlled temperature at different pulp/Na2HPO4 ratios (4:1, 2:1, 5:4 and 1:1). The N2 adsorption/desorption isotherms showed ACs with high quantities of mesopores and micropores and specific surface areas of 140, 150, 450 and 440 m(2)g(-1) for AC 4:1, AC 2:1, AC 5:4 and AC 1:1, respectively. The prepared material AC 5:4 showed a higher removal capacity of the organic contaminants methylene blue (MB), direct red (DR) and phenol than did a Merck AC. The maximum capacities for this AC are approximately 150, 120 and 120 mg g(-1) for MB, DR and phenol, respectively. Thus, a good adsorbent was obtained from coffee pulp, an abundant Brazilian residue.

Headgroup effects of template monolayers on the adsorption behavior and conformation of glucose oxidase adsorbed at air/liquid interfaces.

PubMed

Wang, Ke-Hsuan; Syu, Mei-Jywan; Chang, Chien-Hsiang; Lee, Yuh-Lang

2011-06-21

Stearic acid (SA) and octadecylamine (ODA) monolayers at the air/liquid interface were used as template layers to adsorb glucose oxidase (GOx) from aqueous solution. The effect of the template monolayers on the adsorption behavior of GOx was studied in terms of the variation of surface pressure, the evolution of surface morphology observed by BAM and AFM, and the conformation of adsorbed GOx. The results show that the presence of a template monolayer can enhance the adsorption rate of GOx; furthermore, ODA has a higher ability, compared to SA, to adsorb GOx, which is attributed to the electrostatic attractive interaction between ODA and GOx. For adsorption performed on a bare surface or on an SA monolayer, the surface pressure approaches an equilibrium value (ca. 8 mN/m) after 2 to 3 h of adsorption and remains nearly constant in the following adsorption process. For the adsorption on an ODA monolayer, the surface pressure will increase further 1 to 2 h after approaching the first equilibrium pressure, which is termed the second adsorption stage. The measurement of circular dichroism (CD) spectroscopy indicates that the Langmuir-Blodgett films of adsorbed GOx transferred at the first equilibrium state (π = 8 mN/m) have mainly a β-sheet conformation, which is independent of the type of template monolayers. However, the ODA/GOx LB film transferred at the second adsorption stage has mainly an α-helix conformation. It is concluded that the specific interaction between ODA and GOx not only leads to a higher adsorption rate and adsorbed amount of GOx but also induces a conformation change in adsorbed GOx from β-sheet to α-helix. The present results indicate that is possible to control the conformation of adsorbed protein by selecting the appropriate template monolayer. © 2011 American Chemical Society

A novel approach for arsenic adsorbents regeneration using MgO.

PubMed

Tresintsi, Sofia; Simeonidis, Konstantinos; Katsikini, Maria; Paloura, Eleni C; Bantsis, Georgios; Mitrakas, Manassis

2014-01-30

An integrated procedure for the regeneration of iron oxy-hydroxide arsenic adsorbents by granulated MgO is proposed in this study. A continuous recirculation configuration, with a NaOH solution flowing sequentially through the saturated adsorbent (leaching step) and the MgO (adsorption step) column beds, was optimized by utilizing the high arsenic adsorption efficiency of MgO at strong alkaline environments. Experimental results indicated that the total amount of leached arsenic was captured by MgO whereas the regenerated iron oxy-hydroxide recovered around 80% of its removal capacity upon reuse. The improved adsorption capacity of MgO for As(V), which is maximized at pH 10, is explained by the intermediate hydration to Mg(OH)2 and the following As(V) oxy-anions adsorption on its surface through the formation of monodentate inner sphere complexes, as it is deduced from the AsK-edge X-ray absorption fine structure (EXAFS) analysis. In addition to the economical-benefits, corresponding tests proved that the solid wastes of this process, namely spent MgO/Mg(OH)2, can be environmentally safely disposed as stable additives in cement products, while the alkaline solution is completely detoxified and can be recycled to the regeneration task. Copyright © 2013 Elsevier B.V. All rights reserved.

Magnetic nano graphene oxide as solid phase extraction adsorbent coupled with liquid chromatography to determine pseudoephedrine in urine samples.

PubMed

Taghvimi, Arezou; Hamishehkar, Hamed; Ebrahimi, Mahmoud

2016-01-15

This paper reports on a method based on magnetic solid phase extraction (MSPE) for the determination of pseudoephedrine. Magnetic nanographene oxide (MNGO) was applied as a new adsorbent for the extraction of pseudoephedrine from urine samples. Synthesis of MNGO was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The main factors influencing extraction efficiency, including the amounts of sample volume, amount of adsorbent, type and amount of extraction organic solvent, time of extraction and desorption, pH, ionic strength of extraction medium, and agitation rate, were investigated and optimized. Under optimized extraction conditions, a good linearity was observed in the range of 100-2000ng/mL with a correlation coefficient of 0.9908 (r(2)). Limit of detection (LOD) and limit of quantification (LOQ) were 25 and 82.7ng/mL, respectively. Inter-day and intra-day precision and accuracy were 6.01 and 0.34 (%), and 8.70 and 0.29 (%), respectively. The method was applied for the determination of pseudoephedrine in urine samples of volunteers receiving pseudoephedrine with the recovery of 96.42. It was concluded that the proposed method can be applied in diagnostic clinics. Copyright © 2015 Elsevier B.V. All rights reserved.

Interplay of polyelectrolytes with different adsorbing surfaces

NASA Astrophysics Data System (ADS)

Xie, Feng

We study the adsorption of polyelectrolytes from solution onto different adsorbing surfaces, focusing on the electrostatic interactions. Measurements of the surface excess, fractional ionization of chargeable groups, segmental orientation, and adsorption kinetics were made using Fourier transform infrared spectroscopy in the mode of attenuated total reflection. Different adsorbing surfaces, from single solid surfaces, solid surfaces modified with adsorbed polymer layer, to fluid-like surfaces-biomembranes were adopted. Both atomic force microscopy (AFM) and fluorescent techniques were employed to investigate the fluid-like surfaces in the absence and in the presence of polyelectrolytes. The work focuses on three primary issues: (i) the charge regulation of weak polyelectrolytes on both homogeneous and heterogeneous surfaces, (ii) the dynamics of adsorption when the surface possesses reciprocal mobility, i.e., biomembrane surface, and (iii) the structural and dynamical properties of the fluid-like surfaces interacting with polyelectrolytes. We find that the ionization of chargeable groups in weak polyelectrolytes is controlled by the charge balance between the adsorbates and the surfaces. A new interpretation of ionization in the adsorbed layer provides a new insight into the fundamental problem of whether ions of opposite charge associate or remain separate. Bjerrum length is found to be a criterion for the onset of surface ionization suppression, which helps to predict and control the conformation transition of proteins. In addition to the effect of different surfaces on the adsorption behavior of polyelectrolytes, we also focused on the response of the surfaces to the adsorbates. Chains that encountered sparsely-covered surfaces spread to maximize the number of segment-surface contacts at rates independent of the molar mass. Surface reconstruction rather than molar mass of the adsorbing molecules appeared to determine the rate of spreading. This contrasts starkly

Penicillium sp. strain that efficiently adsorbs lignosulfonate in the presence of sulfate ion.

PubMed

Aoyama, Akihisa; Kurane, Ryuichiro; Nagai, Kazuo

2013-03-01

Lignin is one of the major water insoluble substances that support the physical properties of plants and can be solubilized by sulfite or alkaline treatment in accordance with pulpification. The lignin derivatives produced by both the sulfite and the kraft processes are called lignosulfonate (LS) and kraft lignin (KL), respectively, and both derivatives show a broad spectrum of optical absorbance from ultraviolet to visible light. When the spore suspension of an isolated Penicillium sp., Penicillium sp. A, was inoculated to a medium containing 0.1% commercial LS, absorbance at 480 nm (A480) almost completely disappeared after 5 days of cultivation. Maximum decolorization of the culture broth was observed when the microbe was cultured in the 0.8% LS medium reaching 88%, and the amount of LS removed was calculated to be 7 g/L. In a similar assay with the dark-liquid containing KL, 80% of the A480 of a 20% (v/v) dark-liquid medium disappeared after 5 days of culturing and the amount of KL removed was calculated to be 2.9 g/L. These values significantly exceeded the previously reported amounts with respect to substrate concentration and decolorization. Furthermore, since similar results were obtained in the cases of both LS and KL, it is expected that the present strain is able to non-specifically adsorb a wide range of lignin derivatives, because most of the colored substances were recovered in the culture sediments. Thus, the strain can be used to clean up waste fluids containing water soluble lignin derivatives, adsorb lignin derivatives in waste fluids before dehydration. Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Extracting Uranium from Seawater: Promising AF Series Adsorbents

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

Das, S.; Oyola, Y.; Mayes, Richard T.

A new family of high-surface-area polyethylene fiber adsorbents named the AF series was recently developed at the Oak Ridge National Laboratory (ORNL). The AF series adsorbents were synthesized by radiation-induced graft polymerization of acrylonitrile and itaconic acid (at different monomer/comonomer mol ratios) onto high surface area polyethylene fibers. The degree of grafting (%DOG) of AF series adsorbents was found to be 154-354%. The grafted nitrile groups were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with 0.44 M KOH at 80 °C followed by screening at ORNL with sodium-based synthetic aqueous solution, spiked withmore » 8 ppm uranium. The uranium adsorption capacity in simulated seawater screening ranged from 170 to 200 g-U/kg-ads irrespective of %DOG. A monomer/comonomer molar ratio in the range of 7.57-10.14 seemed to be optimum for highest uranium loading capacity. Subsequently, the adsorbents were also tested with natural seawater at Pacific Northwest National Laboratory (PNNL) using flow-through column experiments to determine uranium loading capacity with varying KOH conditioning times at 80 °C. The highest adsorption capacity of AF1 measured after 56 days of marine testing was demonstrated as 3.9 g-U/kg-adsorbent and 3.2 g-U/kg-adsorbent for 1 and 3 h of KOH conditioning at 80 °C, respectively. Based on capacity values of several AF1 samples, it was observed that changing KOH conditioning from 1 to 3 h at 80 °C resulted in a 22-27% decrease in uranium adsorption capacity in seawater.« less

Selectivity of β-Sitosterol Imprinted Polymers as Adsorbent

NASA Astrophysics Data System (ADS)

Fauziah, St.; Hariani Soekamto, Nunuk; Taba, Paulina; Bachri Amran, Muh

2018-03-01

Molecularly Imprinted Polymers (MIPs) are smart materials that have been used as adsorbents in separation processes of compounds because they have a memorial effect to a certain compound. In this research, MIP synthesized was used as adsorbent for β-sitosterol. The objective of the research was to know the selectivity of MIP in adsorbing β-sitosterol. The concentrations of β-sitosterol after adsorption and desorption were analyzed by a UV-Vis spectrophotometer and the selectivity test was analyzed by HPLC. Result showed that the MIP had high adsorption ability ( qe ). The recovery of β-sitosterol from MIP for the adsorption-desorption process was 68.48%. The MIP was very selective to β-sitosterol compared to cholesterol because it can adsorb β-sitosterol as many as 100%, whereas the adsorption of cholesterol was only 30.27 %.

Biodegradable metal adsorbent synthesized by graft polymerization onto nonwoven cotton fabric

NASA Astrophysics Data System (ADS)

Sekine, Ayako; Seko, Noriaki; Tamada, Masao; Suzuki, Yoshio

2010-01-01

A fibrous adsorbent for Hg ions was synthesized by radiation-induced emulsion graft polymerization of glycidyl methacrylate (GMA) onto a nonwoven cotton fabric and subsequent chemical modification. The optimal pre-irradiation dose for initiation of the graft polymerization of GMA, which minimized the effects of radiation damage on the mechanical strength of the nonwoven cotton fabric, was found to be 10 kGy. The GMA-grafted nonwoven cotton fabric was subsequently modified with ethylenediamine (EDA) or diethylenetriamine (DETA) to obtain a Hg adsorbent. The resulting amine-type adsorbents were evaluated for batch and continuous adsorption of Hg. In batch adsorption, the distribution coefficients of Hg reached 1.9×10 5 and 1.0×10 5 for EDA- and DETA-type adsorbents, respectively. A column packed with EDA-type adsorbent removed Hg from 1.8 ppm Hg solution at a space velocity of 100 h -1, which corresponds to 16,000 times the volume of the packed adsorbent. The adsorbed Hg on the EDA-type adsorbent could be completely eluted by 1 M HCl solution. A microbial oxidative degradation test revealed that the EDA-type adsorbent is biodegradable.

Nanopore reactive adsorbents for the high-efficiency removal of waste species

DOEpatents

Yang, Arthur Jing-Min; Zhang, Yuehua

2005-01-04

A nanoporous reactive adsorbent incorporates a relatively small number of relatively larger reactant, e.g., metal, enzyme, etc., particles (10) forming a discontinuous or continuous phase interspersed among and surrounded by a continuous phase of smaller adsorbent particles (12) and connected interstitial pores (14) therebetween. The reactive adsorbent can effectively remove inorganic or organic impurities in a liquid by causing the liquid to flow through the adsorbent. For example, silver ions may be adsorbed by the adsorbent particles (12) and reduced to metallic silver by reducing metal, such as ions, as the reactant particles (10). The column can be regenerated by backwashing with the liquid effluent containing, for example, acetic acid.

Gold recovery from low concentrations using nanoporous silica adsorbent

NASA Astrophysics Data System (ADS)

Aledresse, Adil

The development of high capacity adsorbents with uniform porosity denoted 5%MP-HMS (5% Mercaptopropyl-Hexagonal Mesoporous Structure) to extract gold from noncyanide solutions is presented. The preliminary studies from laboratory simulated noncyanide gold solutions show that the adsorption capacities of these materials are among the highest reported. The high adsorption saturation level of these materials, up to 1.9 mmol/g (37% of the adsorbent weight) from gold chloride solutions (potassium tetrachloroaurate) and 2.9 mmol/g (57% of the adsorbent weight) from gold bromide solutions (potassium tetrabromoaurate) at pH = 2, is a noteworthy feature of these materials. This gold loading from [AuC4]- and [AuBr4 ]- solutions corresponds to a relative Au:S molar ratio of 2.5:1 and 3.8:1, respectively. These rates are significantly higher than the usual 1:1 (Au:S) ratio expected for metal ion binding with the material. The additional gold ions loaded have been spontaneously reduced to metallic gold in the mesoporous material. Experimental studies indicated high maximum adsorptions of gold as high as 99.9% recovery. Another promising attribute of these materials is their favourable adsorption kinetics. The MP-HMS reaches equilibrium (saturation) in less than 1 minute of exposure in gold bromide and less than 10 minutes in gold chloride. The MP-HMS materials adsorption is significantly improved by agitation and the adsorption capacity of Au (III) ions increases with the decrease in pH. The recovery of adsorbed gold and the regeneration of spent adsorbent were investigated for MP-HMS adsorbent. The regenerated adsorbent (MP-HMS) maintained its adsorption capacity even after repeated use and all the gold was successfully recovered from the spent adsorbent. For the fist time, a promising adsorbent system has been found that is capable of effectively concentrating gold thiosulphate complexes, whereas conventional carbon-inpulp (CIP) and carbon-in-leach (CIL) systems fail. The

Adsorption of β-galactosidase on silica and aluminosilicate adsorbents

NASA Astrophysics Data System (ADS)

Atyaksheva, L. F.; Dobryakova, I. V.; Pilipenko, O. S.

2015-03-01

It is shown that adsorption of β-galactosidase of Aspergillus oryzae fungi on mesoporous and biporous silica and aluminosilicate adsorbents and the rate of the process grow along with the diameter of the pores of the adsorbent. It is found that the shape of the adsorption isotherms changes as well, depending on the texture of the adsorbent: the Michaelis constant rises from 0.3 mM for the enzyme in solution to 0.4-0.5 mM for the enzyme on a surface in the hydrolysis of o-nitrophenyl-β-D-galactopyranoside. It is concluded that β-galactosidase displays its maximum activity on the surface of biporous adsorbents.

Carbonaceous adsorbent regeneration and halocarbon displacement by hydrocarbon gases

DOEpatents

Senum, G.I.; Dietz, R.N.

1994-04-05

This invention describes a process for regeneration of halocarbon bearing carbonaceous adsorbents through which a carbonaceous adsorbent is contacted with hydrocarbon gases, preferably propane, butane and pentane at near room temperatures and at atmospheric pressure. As the hydrocarbon gases come in contact with the adsorbent, the hydrocarbons displace the halocarbons by physical adsorption. As a result of using this process, the halocarbon concentration and the hydrocarbon eluant is increased thereby allowing for an easier recovery of pure halocarbons. By using the process of this invention, carbonaceous adsorbents can be regenerated by an inexpensive process which also allows for subsequent re-use of the recovered halocarbons. 8 figures.

Carbonaceous adsorbent regeneration and halocarbon displacement by hydrocarbon gases

DOEpatents

Senum, Gunnar I.; Dietz, Russell N.

1994-01-01

This invention describes a process for regeneration of halocarbon bearing carbonaceous adsorbents through which a carbonaceous adsorbent is contacted with hydrocarbon gases, preferably propane, butane and pentane at near room temperatures and at atmospheric pressure. As the hydrocarbon gases come in contact with the adsorbent, the hydrocarbons displace the halocarbons by physical adsorption. As a result of using this process, the halocarbon concentration and the hydrocarbon eluant is increased thereby allowing for an easier recovery of pure halocarbons. By using the process of this invention, carbonaceous adsorbents can be regenerated by an inexpensive process which also allows for subsequent re-use of the recovered halocarbons.

Thermal properties of adsorbed molecule in external field

NASA Astrophysics Data System (ADS)

Devi, Sumana; Vidhani, Bhavna; Prasad, Vinod

2018-05-01

Thermodynamic properties such as free energy, internal energy, entropy and specific heat of an adsorbed molecule are systematically investigated in static electric field for four different confinements. The confined potentials taken are suitable for different experimental conditions and are very useful in determining properties of molecules adsorbed under different environments. The time independent Schrödinger equation is solved numerically using accurate 9-point finite difference method. The Energy spectrum thus obtained is used to find thermal properties of the adsorbed molecule. Interesting results are obtained and explained.

Membrane Perturbation Induced by Interfacially Adsorbed Peptides

PubMed Central

Zemel, Assaf; Ben-Shaul, Avinoam; May, Sylvio

2004-01-01

The structural and energetic characteristics of the interaction between interfacially adsorbed (partially inserted) α-helical, amphipathic peptides and the lipid bilayer substrate are studied using a molecular level theory of lipid chain packing in membranes. The peptides are modeled as “amphipathic cylinders” characterized by a well-defined polar angle. Assuming two-dimensional nematic order of the adsorbed peptides, the membrane perturbation free energy is evaluated using a cell-like model; the peptide axes are parallel to the membrane plane. The elastic and interfacial contributions to the perturbation free energy of the “peptide-dressed” membrane are evaluated as a function of: the peptide penetration depth into the bilayer's hydrophobic core, the membrane thickness, the polar angle, and the lipid/peptide ratio. The structural properties calculated include the shape and extent of the distorted (stretched and bent) lipid chains surrounding the adsorbed peptide, and their orientational (C-H) bond order parameter profiles. The changes in bond order parameters attendant upon peptide adsorption are in good agreement with magnetic resonance measurements. Also consistent with experiment, our model predicts that peptide adsorption results in membrane thinning. Our calculations reveal pronounced, membrane-mediated, attractive interactions between the adsorbed peptides, suggesting a possible mechanism for lateral aggregation of membrane-bound peptides. As a special case of interest, we have also investigated completely hydrophobic peptides, for which we find a strong energetic preference for the transmembrane (inserted) orientation over the horizontal (adsorbed) orientation. PMID:15189858

Live microbial cells adsorb Mg2+ more effectively than lifeless organic matter

NASA Astrophysics Data System (ADS)

Qiu, Xuan; Yao, Yanchen; Wang, Hongmei; Duan, Yong

2018-03-01

The Mg2+ content is essential in determining different Mg-CaCO3 minerals. It has been demonstrated that both microbes and the organic matter secreted by microbes are capable of allocating Mg2+ and Ca2+ during the formation of Mg-CaCO3, yet detailed scenarios remain unclear. To investigate the mechanism that microbes and microbial organic matter potentially use to mediate the allocation of Mg2+ and Ca2+ in inoculating systems, microbial mats and four marine bacterial strains ( Synechococcus elongatus, Staphylococcus sp., Bacillus sp., and Desulfovibrio vulgaris) were incubated in artificial seawater media with Mg/Ca ratios ranging from 0.5 to 10.0. At the end of the incubation, the morphology of the microbial mats and the elements adsorbed on them were analyzed using scanning electronic microscopy (SEM) and energy diffraction spectra (EDS), respectively. The content of Mg2+ and Ca2+ adsorbed by the extracellular polysaccharide substances (EPS) and cells of the bacterial strains were analyzed with atomic adsorption spectroscopy (AAS). The functional groups on the surface of the cells and EPS of S. elongatus were estimated using automatic potentiometric titration combined with a chemical equilibrium model. The results show that live microbial mats generally adsorb larger amounts of Mg2+ than Ca2+, while this rarely is the case for autoclaved microbial mats. A similar phenomenon was also observed for the bacterial strains. The living cells adsorb more Mg2+ than Ca2+, yet a reversed trend was observed for EPS. The functional group analysis indicates that the cell surface of S. elongatus contains more basic functional groups (87.24%), while the EPS has more acidic and neutral functional groups (83.08%). These features may be responsible for the different adsorption behavior of Mg2+ and Ca2+ by microbial cells and EPS. Our work confirms the differential Mg2+ and Ca2+ mediation by microbial cells and EPS, which may provide insight into the processes that microbes use to

Verification of chloride adsorption effect of mortar with salt adsorbent

NASA Astrophysics Data System (ADS)

Hoshina, T.; Nakajima, N.; Sudo, H.; Date, S.

2017-11-01

In order to investigate the chloride adsorption effect of mortar mixed with chloride adsorbent, electrophoresis test using mortar specimen and immersion dry repeated test were conducted to evaluate chloride adsorption effect. As a result, it was confirmed that soluble salt content that causes corrosion of rebar in the specimen was reduced by the chloride adsorbent and corrosion inhibiting effect of the rebar was also obtained. It was also confirmed that by increasing dosage of the chloride adsorbent, the chloride adsorbing effect becomes larger as well..

Adsorption characteristics of benzene on biosolid adsorbent and commercial activated carbons.

PubMed

Chiang, Hung-Lung; Lin, Kuo-Hsiung; Chen, Chih-Yu; Choa, Ching-Guan; Hwu, Ching-Shyung; Lai, Nina

2006-05-01

This study selected biosolids from a petrochemical waste-water treatment plant as the raw material. The sludge was immersed in 0.5-5 M of zinc chloride (ZnCl2) solutions and pyrolyzed at different temperatures and times. Results indicated that the 1-M ZnCl2-immersed biosolids pyrolyzed at 500 degrees C for 30 min could be reused and were optimal biosolid adsorbents for benzene adsorption. Pore volume distribution analysis indicated that the mesopore contributed more than the macropore and micropore in the biosolid adsorbent. The benzene adsorption capacity of the biosolid adsorbent was 65 and 55% of the G206 (granular-activated carbon) and BPL (coal-based activated carbon; Calgon, Carbon Corp.) activated carbons, respectively. Data from the adsorption and desorption cycles indicated that the benzene adsorption capacity of the biosolid adsorbent was insignificantly reduced compared with the first-run capacity of the adsorbent; therefore, the biosolid adsorbent could be reused as a commercial adsorbent, although its production cost is high.

Radiation grafted adsorbents for newly emerging environmental applications

NASA Astrophysics Data System (ADS)

Mahmoud Nasef, Mohamed; Ting, T. M.; Abbasi, Ali; Layeghi-moghaddam, Alireza; Sara Alinezhad, S.; Hashim, Kamaruddin

2016-01-01

Radiation induced grafting (RIG) is acquired to prepare a number of adsorbents for newly emerging environmental applications using a single route involving RIG of glycidymethacrylate (GMA) onto polyethylene-polypropylene (PE-PP) non-woven fabric. The grafted fabric was subjected to one of three functionalization reactions to impart desired ionic characters. This included treatment with (1) N-dimethyl-D-glucamine, (2) triethylamine and (3) triethylamine and alkalisation with KOH. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) were used to study the changes in chemical and physical structures of the obtained fibrous adsorbents. The potential applications of the three adsorbents for removal of boron from solutions, capturing CO2 from CO2/N2 mixtures and catalysing transesterification of triacetin/methanol to methyl acetate (biodiesel) were explored. The obtained fibrous adsorbents provide potential alternatives to granular resins for the investigated applications and require further development.

Atomic scale friction of molecular adsorbates during diffusion.

PubMed

Lechner, B A J; de Wijn, A S; Hedgeland, H; Jardine, A P; Hinch, B J; Allison, W; Ellis, J

2013-05-21

Experimental observations suggest that molecular adsorbates exhibit a larger friction coefficient than atomic species of comparable mass, yet the origin of this increased friction is not well understood. We present a study of the microscopic origins of friction experienced by molecular adsorbates during surface diffusion. Helium spin-echo measurements of a range of five-membered aromatic molecules, cyclopentadienyl, pyrrole, and thiophene, on a copper(111) surface are compared with molecular dynamics simulations of the respective systems. The adsorbates have different chemical interactions with the surface and differ in bonding geometry, yet the measurements show that the friction is greater than 2 ps(-1) for all these molecules. We demonstrate that the internal and external degrees of freedom of these adsorbate species are a key factor in the underlying microscopic processes and identify the rotation modes as the ones contributing most to the total measured friction coefficient.

Removal of Direct Red 12B by garlic peel as a cheap adsorbent: Kinetics, thermodynamic and equilibrium isotherms study of removal

NASA Astrophysics Data System (ADS)

Asfaram, A.; Fathi, M. R.; Khodadoust, S.; Naraki, M.

2014-06-01

The removal of dyes from industrial waste is very important from health and hygiene point of view and for environmental protection. In this work, efficiency and performance of garlic peel (GP) adsorbent for the removal of Direct Red 12B (DR12B) from wastewater was investigated. The influence of variables including pH, concentration of the dye and amount of adsorbent, particle size, contact time and temperature on the dye removal has been investigated. It was observed that the pseudo-second-order kinetic model fits better with good correlation coefficient and the equilibrium data fitted well with the Langmuir model. More than 99% removal efficiency was obtained within 25 min at adsorbent dose of 0.2 g per 50 ml for initial dye concentration of 50 mg L-1. Calculation of various thermodynamic parameters such as, Gibb's free energy, entropy and enthalpy of the on-going adsorption process indicate feasibility and endothermic nature of DR12B adsorption.

The Application Law of Large Numbers That Predicts The Amount of Actual Loss in Insurance of Life

NASA Astrophysics Data System (ADS)

Tinungki, Georgina Maria

2018-03-01

The law of large numbers is a statistical concept that calculates the average number of events or risks in a sample or population to predict something. The larger the population is calculated, the more accurate predictions. In the field of insurance, the Law of Large Numbers is used to predict the risk of loss or claims of some participants so that the premium can be calculated appropriately. For example there is an average that of every 100 insurance participants, there is one participant who filed an accident claim, then the premium of 100 participants should be able to provide Sum Assured to at least 1 accident claim. The larger the insurance participant is calculated, the more precise the prediction of the calendar and the calculation of the premium. Life insurance, as a tool for risk spread, can only work if a life insurance company is able to bear the same risk in large numbers. Here apply what is called the law of large number. The law of large numbers states that if the amount of exposure to losses increases, then the predicted loss will be closer to the actual loss. The use of the law of large numbers allows the number of losses to be predicted better.

Determination of Adsorption Equations for Chloro Derivatives of Aniline on Halloysite Adsorbents Using Inverse Liquid Chromatography.

PubMed

Słomkiewicz, Piotr M; Szczepanik, Beata; Garnuszek, Magdalena; Rogala, Paweł; Witkiewicz, Zygfryd

2017-11-01

Chloro derivatives of aniline are commonly used in the production of dyes, pharmaceuticals, and agricultural agents. They are toxic compounds with a large accumulation ability and low natural biodegradability. Halloysite is known as an efficient adsorbent of toxic compounds, such as phenols or herbicides, from wastewater. Inverse LC was applied to measure the adsorption of aniline and 2-chloroaniline (2-CA), 3-chloroaniline (3-CA), and 4-chloroaniline (4-CA) on halloysite adsorbents. A peak division (PD) method was used to determine a Langmuir equation in accordance with the adsorption measurement results. The values of adsorption equilibrium constants and enthalpy were determined and compared by breakthrough curve and PD methods. The physical sense of the calculated adsorption enthalpy values was checked by applying Boudart's entropy criteria. Of note, adsorption enthalpy values for halloysite adsorbents decreased in the following order: aniline > 4-CA > 2-CA > 3-CA.

Magnetic copper-based metal organic framework as an effective and recyclable adsorbent for removal of two fluoroquinolone antibiotics from aqueous solutions.

PubMed

Wu, Gege; Ma, Jiping; Li, Shuang; Guan, Jing; Jiang, Bo; Wang, Liyan; Li, Jinhua; Wang, Xiaoyan; Chen, Lingxin

2018-05-30

Fe 3 O 4 /HKUST-1 magnetic copper based metal-organic frameworks (MOF) were synthesized by a simple and facile method and applied as an effective and recyclable adsorbent for the adsorptive removal of two widely used ciprofloxacin (CIP) and norfloxacin (NOR) fluoroquinolone antibiotics (FQAs) from aqueous solutions. Fe 3 O 4 /HKUST-1 was thoroughly characterized, and the major influence factors including solution pH, adsorbent amount and salt concentration were investigated. Compared to the reported adsorbents, Fe 3 O 4 /HKUST-1 has a very high adsorption rate, and it is found that CIP and NOR could be removed within 30 min. Moreover, the maximum adsorption capacities of the magnetic composites toward CIP and NOR reached as high as 538 mg g -1 and 513 mg g -1 , respectively, much higher than those of most of the reported adsorbents for these two FQAs. The saturation magnetization value of Fe 3 O 4 /HKUST-1 was 44 emu g -1 , which was sufficient for the separation of the Fe 3 O 4 /HKUST-1adsorbent from the aqueous solution by the application of an external magnetic field. Additionally, this magnetic material showed a good reusability with the adsorption capability decreasing only slightly after reuse for ten cycles. These results indicated that the magnetic composites Fe 3 O 4 /HKUST-1 may be a promising adsorbent in the decontamination of FQAs from wastewater due to its high adsorption capability, fast kinetics, easy separation from water, and excellent recyclability. The adsorption mechanism was proposed based on the effects of pH on adsorption and on the zeta potential of the adsorbent. For the adsorption of CIP and NOR by Fe 3 O 4 /HKUST-1, both electrostatic and π-π interactions may be important. Copyright © 2018 Elsevier Inc. All rights reserved.

Black Molecular Adsorber Coatings for Spaceflight Applications

NASA Technical Reports Server (NTRS)

Abraham, Nithin Susan; Hasegawa, Mark Makoto; Straka, Sharon A.

2014-01-01

The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

Development and Testing of Molecular Adsorber Coatings

NASA Technical Reports Server (NTRS)

Abraham, Nithin; Hasegawa, Mark; Straka, Sharon

2012-01-01

The effect of on-orbit molecular contamination has the potential to degrade the performance of spaceflight hardware and diminish the lifetime of the spacecraft. For example, sensitive surfaces, such as optical surfaces, electronics, detectors, and thermal control surfaces, are vulnerable to the damaging effects of contamination from outgassed materials. The current solution to protect these surfaces is through the use of zeolite coated ceramic adsorber pucks. However, these pucks and its additional complex mounting hardware requirements result in several disadvantages, such as size, weight, and cost related concerns, that impact the spacecraft design and the integration and test schedule. As a result, a new innovative molecular adsorber coating was developed as a sprayable alternative to mitigate the risk of on-orbit molecular contamination. In this study, the formulation for molecular adsorber coatings was optimized using various binders, pigment treatment methods, binder to pigment ratios, thicknesses, and spray application techniques. The formulations that passed coating adhesion and vacuum thermal cycling tests were further tested for its adsorptive capacity. Accelerated molecular capacitance tests were performed in an innovatively designed multi-unit system containing idealized contaminant sources. This novel system significantly increased the productivity of the testing phase for the various formulations that were developed. Work performed during the development and testing phases has demonstrated successful application of molecular adsorber coatings onto metallic substrates, as well as, very promising results for the adhesion performance and the molecular capacitance of the coating. Continued testing will assist in the qualification of molecular adsorber coatings for use on future contamination sensitive spaceflight missions.

Black molecular adsorber coatings for spaceflight applications

NASA Astrophysics Data System (ADS)

Abraham, Nithin S.; Hasegawa, Mark M.; Straka, Sharon A.

2014-09-01

The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

Trace contaminant studies of HSC adsorbent. M.S. Thesis

NASA Technical Reports Server (NTRS)

Yieh, D. T. N.

1978-01-01

The adsorption and desorption of fifteen trace contaminants on HSC (polyethylenimine coated acrylic ester) adsorbent were experimentally investigated with the following two objectives: to test the removal potential and the adsorption reversibility of the selected trace contaminants, and to test the effect a preadsorbed trace contaminant has on the CO2 adsorption capacity. The experimental method for acquiring the adsorption equilibrium data used is based on the volumetric (or displacement) concept of vacuum adsorption. From the experimental results, it was found that the HSC adsorbent has good adsorption potential for contaminants of alcohol compounds, esters, and benzene compounds; whereas, adsorption of ketone compounds, oxidizing and reducing agents are detrimental to the adsorbent. In addition, all liquid contaminants reduce the CO2 capacity of HSC adsorbent.

Regenerable activated bauxite adsorbent alkali monitor probe

DOEpatents

Lee, S.H.D.

1992-12-22

A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases. 6 figs.

Breakthrough in Xenon Capture and Purification Using Adsorbent-Supported Silver Nanoparticles.

PubMed

Deliere, Ludovic; Coasne, Benoit; Topin, Sylvain; Gréau, Claire; Moulin, Christophe; Farrusseng, David

2016-07-04

Rare gas capture and purification is a major challenge for energy, environment, and health applications. Of utmost importance for the nuclear industry, novel separation processes for Xe are urgently needed for spent nuclear fuel reprocessing and nuclear activity monitoring. The recovered, non-radioactive Xe is also of high economic value for lighting, surgical anesthetic, etc. Here, using adsorption and breakthrough experiments and statistical mechanics molecular simulation, we show the outstanding performance of zeolite-supported silver nanoparticles to capture/separate Xe at low concentrations (0.087-100 ppm). We also establish the efficiency of temperature swing adsorption based on such adsorbents for Xe separation from Kr/Xe mixtures and air streams corresponding to off-gases generated by nuclear reprocessing. This study paves the way for the development of novel, cost-efficient technologies relying on the large selectivity/capacity of adsorbent-supported silver nanoparticles which surpass all materials ever tested. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Three-dimensionally porous graphene: A high-performance adsorbent for removal of albumin-bonded bilirubin.

PubMed

Ma, Chun Fang; Gao, Qiang; Xia, Kai Sheng; Huang, Zhi Yuan; Han, Bo; Zhou, Cheng Gang

2017-01-01

The development of bilirubin adsorbents with high adsorption efficiencies towards albumin-bonded bilirubin is still a considerable challenge. In this work, a three-dimensionally porous graphene (3D-pGR) has been fabricated through a simple carbon dioxide (CO 2 ) activation of thermally exfoliated graphite oxide (EGO). Intriguingly, the resultant 3D-pGR material showed hierarchically micro-meso-macroporous structure, high specific surface area of up to 843m 2 g -1 , and large pore volume as high as 2.71cm 3 g -1 . Besides, the large planar π-configuration structure of 3D-pGR made it possible to compete effectively with albumin for bilirubin binding. Taking advantages of these fantastic characteristics, the 3D-pGR was demonstrated to be extraordinarily efficient for bilirubin removal from a bovine serum albumin (BSA)-rich solution. Under optimized conditions, the maximum adsorption capacity of 3D-pGR for BSA-bonded bilirubin was up to 126.1mgg -1 , which is not only significantly higher than the adsorption capacities of currently available adsorbents towards albumin-bonded bilirubin, but also superior to those of many reported adsorbents towards free bilirubin. In addition, the hemolysis assay of 3D-pGR indicated that this material had negligible hemolysis effect. Findings from this study may open up important new possibilities for removal of protein-bonded toxins. Copyright © 2016 Elsevier B.V. All rights reserved.

Extracting uranium from seawater: Promising AF series adsorbents

DOE PAGES

Das, Sadananda; Oyola, Y.; Mayes, Richard T.; ...

2015-11-02

Here, a new family of high surface area polyethylene fiber adsorbents (AF series) was recently developed at the Oak Ridge National Laboratory (ORNL). The AF series of were synthesized by radiation-induced graft polymerization of acrylonitrile and itaconic acid (at different monomer/co-monomer mol ratios) onto high surface area polyethylene fibers. The degree of grafting (%DOG) of AF series adsorbents was found to be 154 354%. The grafted nitrile groups were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with 0.44M KOH at 80 C followed by screening at ORNL with simulated seawater spiked with 8more » ppm uranium. Uranium adsorption capacity in simulated seawater screening ranged from 170-200 g-U/kg-ads irrespective of %DOG. A monomer/co-monomer mol ratio in the range of 7.57-10.14 seemed to be optimum for highest uranium loading capacity. Subsequently, the adsorbents were also tested with natural seawater at Pacific Northwest National Laboratory (PNNL) using flow-through exposure uptake experiments to determine uranium loading capacity with varying KOH conditioning time at 80 C. The highest adsorption capacity of AF1 measured after 56 days of marine testing was demonstrated as 3.9 g-U/kg-adsorbent and 3.2 g-U/kg-adsorbent for 1hr and 3hrs of KOH conditioning at 80 C, respectively. Based on capacity values of several AF1 samples, it was observed that changing KOH conditioning from 3hrs to 1hr at 80 C resulted in 22-27% increase in uranium loading capacity in seawater.« less

Extracting uranium from seawater: Promising AF series adsorbents

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

Das, Sadananda; Oyola, Y.; Mayes, Richard T.

Here, a new family of high surface area polyethylene fiber adsorbents (AF series) was recently developed at the Oak Ridge National Laboratory (ORNL). The AF series of were synthesized by radiation-induced graft polymerization of acrylonitrile and itaconic acid (at different monomer/co-monomer mol ratios) onto high surface area polyethylene fibers. The degree of grafting (%DOG) of AF series adsorbents was found to be 154 354%. The grafted nitrile groups were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with 0.44M KOH at 80 C followed by screening at ORNL with simulated seawater spiked with 8more » ppm uranium. Uranium adsorption capacity in simulated seawater screening ranged from 170-200 g-U/kg-ads irrespective of %DOG. A monomer/co-monomer mol ratio in the range of 7.57-10.14 seemed to be optimum for highest uranium loading capacity. Subsequently, the adsorbents were also tested with natural seawater at Pacific Northwest National Laboratory (PNNL) using flow-through exposure uptake experiments to determine uranium loading capacity with varying KOH conditioning time at 80 C. The highest adsorption capacity of AF1 measured after 56 days of marine testing was demonstrated as 3.9 g-U/kg-adsorbent and 3.2 g-U/kg-adsorbent for 1hr and 3hrs of KOH conditioning at 80 C, respectively. Based on capacity values of several AF1 samples, it was observed that changing KOH conditioning from 3hrs to 1hr at 80 C resulted in 22-27% increase in uranium loading capacity in seawater.« less

Adsorption of aromatic compounds by carbonaceous adsorbents: a comparative study on granular activated carbon, activated carbon fiber, and carbon nanotubes.

PubMed

Zhang, Shujuan; Shao, Ting; Kose, H Selcen; Karanfil, Tanju

2010-08-15

Adsorption of three aromatic organic compounds (AOCs) by four types of carbonaceous adsorbents [a granular activated carbon (HD4000), an activated carbon fiber (ACF10), two single-walled carbon nanotubes (SWNT, SWNT-HT), and a multiwalled carbon nanotube (MWNT)] with different structural characteristics but similar surface polarities was examined in aqueous solutions. Isotherm results demonstrated the importance of molecular sieving and micropore effects in the adsorption of AOCs by carbonaceous porous adsorbents. In the absence of the molecular sieving effect, a linear relationship was found between the adsorption capacities of AOCs and the surface areas of adsorbents, independent of the type of adsorbent. On the other hand, the pore volume occupancies of the adsorbents followed the order of ACF10 > HD4000 > SWNT > MWNT, indicating that the availability of adsorption site was related to the pore size distributions of the adsorbents. ACF10 and HD4000 with higher microporous volumes exhibited higher adsorption affinities to low molecular weight AOCs than SWNT and MWNT with higher mesopore and macropore volumes. Due to their larger pore sizes, SWNTs and MWNTs are expected to be more efficient in adsorption of large size molecules. Removal of surface oxygen-containing functional groups from the SWNT enhanced adsorption of AOCs.

Old age and underlying interstitial abnormalities are risk factors for development of ARDS after pleurodesis using limited amount of large particle size talc.

PubMed

Shinno, Yuki; Kage, Hidenori; Chino, Haruka; Inaba, Atsushi; Arakawa, Sayaka; Noguchi, Satoshi; Amano, Yosuke; Yamauchi, Yasuhiro; Tanaka, Goh; Nagase, Takahide

2018-01-01

Talc pleurodesis is commonly performed to manage refractory pleural effusion or pneumothorax. It is considered as a safe procedure as long as a limited amount of large particle size talc is used. However, acute respiratory distress syndrome (ARDS) is a rare but serious complication after talc pleurodesis. We sought to determine the risk factors for the development of ARDS after pleurodesis using a limited amount of large particle size talc. We retrospectively reviewed patients who underwent pleurodesis with talc or OK-432 at the University of Tokyo Hospital. Twenty-seven and 35 patients underwent chemical pleurodesis using large particle size talc (4 g or less) or OK-432, respectively. Four of 27 (15%) patients developed ARDS after talc pleurodesis. Patients who developed ARDS were significantly older than those who did not (median 80 vs 66 years, P = 0.02) and had a higher prevalence of underlying interstitial abnormalities on chest computed tomography (CT; 2/4 vs 1/23, P < 0.05). No patient developed ARDS after pleurodesis with OK-432. This is the first case series of ARDS after pleurodesis using a limited amount of large particle size talc. Older age and underlying interstitial abnormalities on chest CT seem to be risk factors for developing ARDS after talc pleurodesis. © 2017 Asian Pacific Society of Respirology.

EMERGING TECHNOLOGY SUMMARY: DEMONSTRATION OF AMBERSORB 563 ADSORBENT TECHNOLOGY

EPA Science Inventory

A field pilot study was conducted to demonstrate the technical feasibility and cost-effectiveness of Ambersorb® 5631 carbonaceous adsorbent for remediating groundwater contaminated with volatile organic compounds (VOCs). The Ambersorb adsorbent technology demonstration consist...

Removal of arsenic from water using nano adsorbents and challenges: A review.

PubMed

Lata, Sneh; Samadder, S R

2016-01-15

Many researchers have used nanoparticles as adsorbents to remove water pollutants including arsenic after modifying the properties of nanoparticles by improving reactivity, biocompatibility, stability, charge density, multi-functionalities, and dispersibility. For arsenic removal, nano adsorbents emerged as the potential alternatives to existing conventional technologies. The present study critically reviewed the past and current available information on the potential of nano adsorbents for arsenic removal from contaminated water and the challenges involved in that. The study discussed the separation and regeneration techniques of nano adsorbents and the performance thereof. The study evaluated the adsorption efficiency of the various nanoparticles based on size of nanoparticles, types of nano adsorbents, method of synthesis, separation and regeneration of the nano adsorbents. The study found that more studies are required on suitable holding materials for the nano adsorbents to improve the permeability and to make the technology applicable at the field condition. The study will help the readers to choose suitable nanomaterials and to take up further research required for arsenic removal using nano adsorbents. Copyright © 2015 Elsevier Ltd. All rights reserved.

The influence of adsorbent microstructure upon adsorption equilibria: Investigations of a model system

NASA Astrophysics Data System (ADS)

Kaminsky, R. D.; Monson, P. A.

1991-08-01

We present a theoretical study of the influence of the microstructure of a porous adsorbent upon associated adsorption behavior. A model is developed which describes the interactions of adsorbed molecules with an adsorbent treated as a matrix of particles each of which is a continuum of interaction centers. The model leads to an analytic expression for the adsorbate-adsorbent particle potential which is an analog of the 9-3 potential model for adsorption on planar solid surfaces. To illustrate the utility of the approach, an application to methane adsorbed in a microporous silica gel is presented. Several adsorbent microstructures are investigated, including a variety of crystal lattices as well as structures derived from equilibrium configurations of hard spheres. Adsorption in these structures is studied through calculation of Henry's law constants and by using grand canonical Monte Carlo simulation to determine adsorption isotherms and the structure of adsorbed fluids. The results obtained are related to details of the adsorbent microstructure.

Evaluation of Flush-Mounted, S-Duct Inlets with Large Amounts of Boundary Layer Ingestion

NASA Technical Reports Server (NTRS)

Berrier, Bobby L.; Morehouse, Melissa B.

2003-01-01

A new high Reynolds number test capability for boundary layer ingesting inlets has been developed for the NASA Langley Research Center 0.3-Meter Transonic Cryogenic Tunnel. Using this new capability, an experimental investigation of four S-duct inlet configurations with large amounts of boundary layer ingestion (nominal boundary layer thickness of about 40% of inlet height) was conducted at realistic operating conditions (high subsonic Mach numbers and full-scale Reynolds numbers). The objectives of this investigation were to 1) provide a database for CFD tool validation on boundary layer ingesting inlets operating at realistic conditions and 2) provide a baseline inlet for future inlet flow-control studies. Tests were conducted at Mach numbers from 0.25 to 0.83, Reynolds numbers (based on duct exit diameter) from 5.1 million to a full-scale value of 13.9 million, and inlet mass-flow ratios from 0.39 to 1.58 depending on Mach number. Results of this investigation indicate that inlet pressure recovery generally decreased and inlet distortion generally increased with increasing Mach number. Except at low Mach numbers, increasing inlet mass-flow increased pressure recovery and increased distortion. Increasing the amount of boundary layer ingestion (by decreasing inlet throat height) or ingesting a boundary layer with a distorted (adverse) profile decreased pressure recovery and increased distortion. Finally, increasing Reynolds number had almost no effect on inlet distortion but increased inlet recovery by about one-half percent at a Mach number near cruise.

Development and characterization of activated hydrochars from orange peels as potential adsorbents for emerging organic contaminants.

PubMed

Fernandez, M E; Ledesma, B; Román, S; Bonelli, P R; Cukierman, A L

2015-05-01

Activated hydrochars obtained from the hydrothermal carbonization of orange peels (Citrus sinensis) followed by various thermochemical processing were assessed as adsorbents for emerging contaminants in water. Thermal activation under flows of CO2 or air as well as chemical activation with phosphoric acid were applied to the hydrochars. Their characteristics were analyzed and related to their ability to uptake three pharmaceuticals (diclofenac sodium, salicylic acid and flurbiprofen) considered as emerging contaminants. The hydrothermal carbonization and subsequent activations promoted substantial chemical transformations which affected the surface properties of the activated hydrochars; they exhibited specific surface areas ranging from 300 to ∼620 m(2)/g. Morphological characterization showed the development of coral-like microspheres dominating the surface of most hydrochars. Their ability to adsorb the three pharmaceuticals selected was found largely dependent on whether the molecules were ionized or in their neutral form and on the porosity developed by the new adsorbents. Copyright © 2015 Elsevier Ltd. All rights reserved.

Carbon/Attapulgite Composites as Recycled Palm Oil-Decoloring and Dye Adsorbents

PubMed Central

Tian, Guangyan; Zhu, Yongfeng; Zong, Li; Kang, Yuru; Wang, Aiqin

2018-01-01

Activated clay minerals have been widely used in the edible oil refining industry for decolorization of crude oil by adsorption, and so far many methods have been used to improve their decolorization efficiency. Herein, we successfully prepared a series of carbon/attapulgite (C/APT) composite adsorbents by a one-step in-situ carbonization process with natural starch (St) as the carbon source. It has been revealed that the adsorbent had better decolorization efficiency for crude palm oil than acid-activated APT. However, more than a million tons of decolorized waste is produced every year in the oil-refining industry, which was often treated as solid waste and has not yet been reutilized effectively. In order to explore a viable method to recycle and reuse the decolorant, the waste decolorant was further prepared into new C/APT adsorbents for the removal of dyes from wastewater, and then the dyes adsorbed on the adsorbent were used as the carbon sources to produce new C/APT adsorbents by a cyclic carbonization process. The results showed that the adsorbents prepared from the decolorized waste could remove more than 99.5% of the methylene blue (MB), methyl violet (MV), and malachite green (MG) dyes from the simulated wastewater with the dye concentration of 200 mg/L, and the C/APT–Re adsorbent consecutively regenerated five times using the adsorbed dyes as a carbon source still exhibit good adsorption efficiency for dyes. As a whole, this process opens a new avenue to develop efficient decolorants of palm oil and achieves recyclable utilization of decolored waste. PMID:29316634

Methotrexate-loaded porous polymeric adsorbents as oral sustained release formulations.

PubMed

Wang, Xiuyan; Yan, Husheng

2017-09-01

Methotrexate as a model drug with poor aqueous solubility was adsorbed into porous polymeric adsorbents, which was used as oral sustained release formulations. In vitro release assay in simulated gastrointestinal fluids showed that the methotrexate-loaded adsorbents showed distinct sustained release performance. The release rate increased with increase in pore size of the adsorbents. In vivo pharmacokinetic study showed that the maximal plasma methotrexate concentrations after oral administration of free methotrexate and methotrexate-loaded DA201-H (a commercial porous polymeric adsorbent) to rats occurred at 40min and 5h post-dose, respectively; and the plasma concentrations decreased to 22% after 5h for free methotrexate and 44% after 24h for methotrexate-loaded DA201-H, respectively. The load of methotrexate into the porous polymeric adsorbents not only resulted in obvious sustained release, but also enhanced the oral bioavailability of methotrexate. The areas under the curve, AUC 0-24 and AUC 0-inf , for methotrexate-loaded DA201-H increased 3.3 and 7.7 times, respectively, compared to those for free methotrexate. Copyright © 2017 Elsevier B.V. All rights reserved.

Differences between tethered polyelectrolyte chains adsorbed onto bare mica and hydrophobically modified mica, comparison with theory.

NASA Astrophysics Data System (ADS)

Balastre, Marc; Tamashiro, Mario N.; Hernandez, Ernesto; Pincus, Philip; Tirrell, Matthew

2001-03-01

End-grafted polymers generated from the adsorption of asymmetric diblock copolymers on solid surface play an important role in many areas of science and technology. While the small insoluble block acts as an anchor, the charged soluble block confers useful properties to the surface. This study looks at tethered layers of poly(styrene sulfonate)/poly(t-butyl styrene) (PtBS-PSS) adsorbed on both mica (hydrophilic) and octadecyltriethoxysilane (OTE) modified mica (hydrophobic). Normal compressing forces at two different constant grafting densities (bare and modified mica) were measured with the surface force apparatus and compared with theoretical prediction. The effect of salt concentration (Cs) upon the thickness of the self-assembled layers (Lo) was measured in each case. For adsorption of diblock copolymers onto OTE the resulting scaling relationship is much closer to the brush theory, Lo Cs-1/3. This result suggests that the adsorbed amount on mica is not high enough to form a brush.

Equilibrium and heat of adsorption of diethyl phthalate on heterogeneous adsorbents.

PubMed

Zhang, Weiming; Xu, Zhengwen; Pan, Bingcai; Hong, Changhong; Jia, Kun; Jiang, Peijuan; Zhang, Qingjian; Pan, Bingjun

2008-09-01

Removal of phthalate esters from water has been of considerable concern recently. In the present study, the adsorptive removal performance of diethyl phthalate (DEP) from water was investigated with the aminated polystyrene resin (NDA-101) and oxidized polystyrene resin (NDA-702). In addition, the commercial homogeneous polystyrene resin (XAD-4) and acrylic ester resin (Amberlite XAD-7) as well as coal-based granular activated carbon (AC-750) were chosen for comparison. The corresponding equilibrium isotherms are well described by the Freundlich equation and the adsorption capacities for DEP followed the order NDA-702 > NDA-101 > AC-750 > XAD-4 > XAD-7. Analysis of adsorption mechanisms suggested that these adsorbents spontaneously adsorb DEP molecules driven mainly by enthalpy change, and the adsorption process was derived by multiple adsorbent-adsorbate interactions such as hydrogen bonding, pi-pi stacking, and micropore filling. The information related to the adsorbent surface heterogeneity and the adsorbate-adsorbate interaction was obtained by Do's model. All the results indicate that heterogeneous resins NDA-702 and NDA-101 have excellent potential as an adsorption material for the removal of DEP from the contaminated water.

Development of silver nanoparticle-doped adsorbents for the separation and recovery of radioactive iodine from alkaline solutions.

PubMed

Kim, Taewoon; Lee, Seung-Kon; Lee, Suseung; Lee, Jun Sig; Kim, Sang Wook

2017-11-01

Removing radioactive iodine from solutions containing fission products is essential for nuclear facility decontamination, radioactive waste treatment, and medical isotope production. For example, the production of high-purity fission 99 Mo by irradiation of 235 U with neutrons involves the removal of iodine from an alkaline solution of the irradiated target (which contains numerous fission products and a large quantity of aluminate ions) using silver-based materials or anion-exchange resins. To be practically applicable, the utilized iodine adsorbent should exhibit a decontamination factor of at least 200. Herein, the separation of radioactive iodine from alkaline solutions was achieved using alumina doped with silver nanoparticles (Ag NPs). Ag NPs have a larger surface area than Ag powder/wires and can thus adsorb iodine more effectively and economically, whereas alumina is a suitable inert support that does not adsorb 99 Mo and is stable under basic conditions. The developed adsorbents with less impurities achieved iodine removal and recovery efficiencies of 99.7 and 62%, respectively, thus being useful for the production of 131 I, a useful medical isotope. Copyright © 2017. Published by Elsevier Ltd.

Vibrational Studies of Adsorbate-Induced Reconstruction on Molybdenum Surfaces.

NASA Astrophysics Data System (ADS)

Lopinski, Gregory Peter

Adsorbate-induced rearrangement of the substrate structure strongly modifies the adsorbate-substrate and adsorbate-adsorbate interactions, leading to the complex behavior observed in many chemisorption systems. In this thesis the H/Mo(211), O/Mo(211) and Na/Mo(100) systems have been studied using high resolution electron energy loss spectroscopy (HREELS) to observe vibrations of the adsorbed atoms. The vibrational data is correlated with observations of the long-range order probed by LEED as well as the work function changes induced by adsorption. Adsorbate -induced substrate reconstruction plays an important role in all three of these systems. Studies of the coadsorption systems O+H/Mo(211) and Na+O/Mo(100) indicate how these effects can influence interactions between adsorbates. For H/Mo(211), above 1ML a (1 x 1) to (1 x 2) transition is observed and attributed to modification of the substrate periodicity. Below 1ML, H atoms are bridge bonded and induce local distortions of the substrate. The transition to the (1 x 2) phase involves the ordering of these displacements and occupation of three-fold sites partially populated by conversion of the bridge bonded species. This conversion accounts for the sawtooth-like coverage dependence of the work function. The structural model proposed for this system is also supported by the desorption parameters and partial molar entropy extracted from adsorption isobars. Oxygen adsorption on Mo(211) involves the occupation of multiple binding sites, with both the long-range order and the local geometry of the adsorbate phases strongly temperature dependent. Coadsorption of low coverages of oxygen and hydrogen leads to segregation of the two adsorbates which can be understood in terms of a substrate-mediated repulsive interaction between O and H. For Na/Mo(100), the frequency of the Na-Mo symmetric stretch mode does not shift with coverage although the mode intensity is strongly coverage dependent. The absence of a frequency shift

Potential of polyaniline modified clay nanocomposite as a selective decontamination adsorbent for Pb(II) ions from contaminated waters; kinetics and thermodynamic study.

PubMed

Piri, Somayeh; Zanjani, Zahra Alikhani; Piri, Farideh; Zamani, Abbasali; Yaftian, Mohamadreza; Davari, Mehdi

2016-01-01

Nowadays significant attention is to nanocomposite compounds in water cleaning. In this article the synthesis and characterization of conductive polyaniline/clay (PANI/clay) as a hybrid nanocomposite with extended chain conformation and its application for water purification are presented. Clay samples were obtained from the central plain of Abhar region, Abhar, Zanjan Province, Iran. Clay was dried and sieved before used as adsorbent. The conductive polyaniline was inflicted into the layers of clay to fabricate a hybrid material. The structural properties of the fabricated nanocomposite are studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). The elimination process of Pb(II) and Cd(II) ions from synthetics aqueous phase on the surface of PANI/clay as adsorbent were evaluated in batch experiments. Flame atomic absorption instrument spectrophotometer was used for determination of the studied ions concentration. Consequence change of the pH and initial metal amount in aqueous solution, the procedure time and the used adsorbent dose as the effective parameters on the removal efficiency was investigated. Surface characterization was exhibited that the clay layers were flaked in the hybrid nanocomposite. The results show that what happen when a nanocomposite polyaniline chain is inserted between the clay layers. The adsorption of ions confirmed a pH dependency procedure and a maximum removal value was seen at pH 5.0. The adsorption isotherm and the kinetics of the adsorption processes were described by Temkin model and pseudo-second-order equation. Time of procedure, pH and initial ion amount have a severe effect on adsorption efficiency of PANI/clay. By using suggested synthesise method, nano-composite as the adsorbent simply will be prepared. The prepared PANI/clay showed excellent adsorption capability for decontamination of Pb ions from contaminated water. Both of suggested synthesise and

Monitoring and Control of an Adsorption System Using Electrical Properties of the Adsorbent for Organic Compound Abatement.

PubMed

Hu, Ming-Ming; Emamipour, Hamidreza; Johnsen, David L; Rood, Mark J; Song, Linhua; Zhang, Zailong

2017-07-05

Adsorption systems typically need gas and temperature sensors to monitor their adsorption/regeneration cycles to separate gases from gas streams. Activated carbon fiber cloth (ACFC)-electrothermal swing adsorption (ESA) is an adsorption system that has the potential to be controlled with the electrical properties of the adsorbent and is studied here to monitor and control the adsorption/regeneration cycles without the use of gas and temperature sensors and to predict breakthrough before it occurs. The ACFC's electrical resistance was characterized on the basis of the amount of adsorbed organic gas/vapor and the adsorbent temperature. These relationships were then used to develop control logic to monitor and control ESA cycles on the basis of measured resistance and applied power values. Continuous sets of adsorption and regeneration cycles were performed sequentially entirely on the basis of remote electrical measurements and achieved ≥95% capture efficiency at inlet concentrations of 2000 and 4000 ppm v for isobutane, acetone, and toluene in dry and elevated relative humidity gas streams, demonstrating a novel cyclic ESA system that does not require gas or temperature sensors. This contribution is important because it reduces the cost and simplifies the system, predicts breakthrough before its occurrence, and reduces emissions to the atmosphere.

Adlayer structure dependent ultrafast desorption dynamics in carbon monoxide adsorbed on Pd (111)

NASA Astrophysics Data System (ADS)

Hong, Sung-Young; Xu, Pan; Camillone, Nina R.; White, Michael G.; Camillone, Nicholas

2016-07-01

We report our ultrafast photoinduced desorption investigation of the coverage dependence of substrate-adsorbate energy transfer in carbon monoxide adlayers on the (111) surface of palladium. As the CO coverage is increased, the adsorption site population shifts from all threefold hollows (up to 0.33 ML), to bridge and near bridge (>0.5 to 0.6 ML) and finally to mixed threefold hollow plus top site (at saturation at 0.75 ML). We show that between 0.24 and 0.75 ML this progression of binding site motifs is accompanied by two remarkable features in the ultrafast photoinduced desorption of the adsorbates: (i) the desorption probability increases roughly two orders magnitude, and (ii) the adsorbate-substrate energy transfer rate observed in two-pulse correlation experiments varies nonmonotonically, having a minimum at intermediate coverages. Simulations using a phenomenological model to describe the adsorbate-substrate energy transfer in terms of frictional coupling indicate that these features are consistent with an adsorption-site dependent electron-mediated energy coupling strength, ηel, that decreases with binding site in the order: three-fold hollow > bridge and near bridge > top site. This weakening of ηel largely counterbalances the decrease in the desorption activation energy that accompanies this progression of adsorption site motifs, moderating what would otherwise be a rise of several orders of magnitude in the desorption probability. Within this framework, the observed energy transfer rate enhancement at saturation coverage is due to interadsorbate energy transfer from the copopulation of molecules bound in three-fold hollows to their top-site neighbors.

Lotus Dust Mitigation Coating and Molecular Adsorber Coating

NASA Technical Reports Server (NTRS)

O'Connor, Kenneth M.; Abraham, Nithin S.

2015-01-01

NASA Goddard Space Flight Center has developed two unique coating formulations that will keep surfaces clean and sanitary and contain contaminants.The Lotus Dust Mitigation Coating, modeled after the self-cleaning, water-repellant lotus leaf, disallows buildup of dust, dirt, water, and more on surfaces. This coating, has been successfully tested on painted, aluminum, glass, silica, and some composite surfaces, could aid in keeping medical assets clean.The Molecular Adsorber Coating is a zeolite-based, sprayable molecular adsorber coating, designed to prevent outgassing in materials in vacuums. The coating works well to adsorb volatiles and contaminates in manufacturing and processing, such as in pharmaceutical production. The addition of a biocide would also aid in controlling bacteria levels.

Polymer-based adsorbent for heavy metals removal from aqueous solution

NASA Astrophysics Data System (ADS)

Mahmud, H. N. M. E.; Huq, A. K. O.; Yahya, R.

2017-06-01

A novel conducting polymer-based adsorbent, polypyrrole (PPy) fine powder has successfully been prepared as a new adsorbent and utilized in the adsorption of heavy metal ions like arsenic, zinc and cadmium ions from aqueous solution. PPy was chemically synthesized by using FeCl3.6H2O as an oxidant. The prepared PPy adsorbent was characterized by Brunauer-Emmet-Teller (BET) surface analysis, field emission scanning electron microscopy (FESEM) and attenuated total reflectance fourier transform infrared ATR-(FTIR) spectroscopy. The adsorption was conducted by varying different parameters such as, contact time, pH and adsorbent dosage. The concentrations of metal ions were measured by inductively coupled plasma mass spectroscopy (ICP-MS). The results show that PPy acts as an effective sorbent for the removal of arsenic, zinc and cadmium ions from aqueous solution. The as-prepared PPy fine powder is easy to prepare and appeared as an effective adsorbent for heavy metal ions particularly arsenic in wastewater treatment.

Arsenic Adsorption from Water Using Graphene-Based Materials as Adsorbents: a Critical Review

NASA Astrophysics Data System (ADS)

Yang, Xuetong; Xia, Ling; Song, Shaoxian

2017-07-01

Adsorption is widely applied to remove arsenic from water. This paper reviewed and compared the recent progresses on the arsenic removal by adsorption using two-dimensional and three-dimensional graphene-based materials as adsorbents. Functional graphene sheet achieved the largest As(III) adsorption capacity of 138.79mg/g, while Mg-Al LDH/GO2 showed the largest As(V) adsorption capacity of 183.11mg/g. Parameters including pH, temperature, co-existing ions and loaded metal or metal oxide affected the adsorption process. The adsorption mechanisms of graphene-based materials for As(III) and As(V) could be explained by surface complexation and the electrostatic attraction, respectively. Future works are suggested to focus on regenerating of two-dimensional graphene-based adsorbents and developing the three-dimensional with large specific surface area and better adsorption performance.

Removal of acutely hazardous pharmaceuticals from water using multi-template imprinted polymer adsorbent.

PubMed

Venkatesh, Avinash; Chopra, Nikita; Krupadam, Reddithota J

2014-05-01

Molecularly imprinted polymer adsorbent has been prepared to remove a group of recalcitrant and acutely hazardous (p-type) chemicals from water and wastewaters. The polymer adsorbent exhibited twofold higher adsorption capacity than the commercially used polystyrene divinylbenzene resin (XAD) and powdered activated carbon adsorbents. Higher adsorption capacity of the polymer adsorbent was explained on the basis of high specific surface area formed during molecular imprinting process. Freundlich isotherms drawn showed that the adsorption of p-type chemicals onto polymer adsorbent was kinetically faster than the other reference adsorbents. Matrix effect on adsorption of p-type chemicals was minimal, and also polymer adsorbent was amenable to regeneration by washing with water/methanol (3:1, v/v) solution. The polymer adsorbent was unaltered in its adsorption capacity up to 10 cycles of adsorption and desorption, which will be more desirable in cost reduction of treatment compared with single-time-use activated carbon.

Food wastes derived adsorbents for carbon dioxide and benzene gas sorption.

PubMed

Opatokun, Suraj Adebayo; Prabhu, Azhagapillai; Al Shoaibi, Ahmed; Srinivasakannan, C; Strezov, Vladimir

2017-02-01

Food wastes are produced worldwide in large quantities that could have potential to produce higher value products, including industrial adsorbents. The present work attempts valorization of food waste by CO 2 activation and functionalization through nitric acid and melamine treatment. The prepared porous materials were subjected to gas phase adsorption of CO 2 and benzene gases. The resultant highly porous carbon materials with surface area range from 797 to 1025 m 2 /g were synthesized showing uptake capacities of 4.41, 4.07, 4.18 and 4.36 mmol/g of CO 2 and 345, 305, 242.5 and 380.7 mg/g of C 6 H 6 respectively for PyF515, PyF520, PyF715 and PyF720 in the absence of doped carbon matrix. Differential thermogravimetric (DTG) analysis showed the thermostability of the precursors to validate selected initial pyrolysis temperatures (500 and 700 °C). C 6 H 6 sorption lies mainly in the physisorption region for all adsorbents ensuring re-generation potential. PyF720 and PyF520 recorded the highest isosteric enthalpy of 64.4 kJ/mol and 48.7 kJ/mol respectively, despite the low degree of coverage of the latter. Thus, PyF515 and PyF720 demonstrated the potential for use as sustainable and cost effective adsorbents for benzene gas containment suitable for swing adsorption system. Copyright © 2016 Elsevier Ltd. All rights reserved.

Magnetic graphene-carbon nanotube iron nanocomposites as adsorbents and antibacterial agents for water purification.

PubMed

Sharma, Virender K; McDonald, Thomas J; Kim, Hyunook; Garg, Vijayendra K

2015-11-01

One of the biggest challenges of the 21st century is to provide clean and affordable water through protecting source and purifying polluted waters. This review presents advances made in the synthesis of carbon- and iron-based nanomaterials, graphene-carbon nanotubes-iron oxides, which can remove pollutants and inactivate virus and bacteria efficiently in water. The three-dimensional graphene and graphene oxide based nanostructures exhibit large surface area and sorption sites that provide higher adsorption capacity to remove pollutants than two-dimensional graphene-based adsorbents and other conventional adsorbents. Examples are presented to demonstrate removal of metals (e.g., Cu, Pb, Cr(VI), and As) and organics (e.g., dyes and oil) by grapheme-based nanostructures. Inactivation of Gram-positive and Gram-negative bacterial species (e.g., Escherichia coli and Staphylococcus aureus) is also shown. A mechanism involving the interaction of adsorbents and pollutants is briefly discussed. Magnetic graphene-based nanomaterials can easily be separated from the treated water using an external magnet; however, there are challenges in implementing the graphene-based nanotechnology in treating real water. Copyright © 2015 Elsevier B.V. All rights reserved.

Framework for scalable adsorbate–adsorbate interaction models

DOE PAGES

Hoffmann, Max J.; Medford, Andrew J.; Bligaard, Thomas

2016-06-02

Here, we present a framework for physically motivated models of adsorbate–adsorbate interaction between small molecules on transition and coinage metals based on modifications to the substrate electronic structure due to adsorption. We use this framework to develop one model for transition and one for coinage metal surfaces. The models for transition metals are based on the d-band center position, and the models for coinage metals are based on partial charges. The models require no empirical parameters, only two first-principles calculations per adsorbate as input, and therefore scale linearly with the number of reaction intermediates. By theory to theory comparison withmore » explicit density functional theory calculations over a wide range of adsorbates and surfaces, we show that the root-mean-squared error for differential adsorption energies is less than 0.2 eV for up to 1 ML coverage.« less

Effect of the morphology of adsorbed oleate on the wettability of a collophane surface

NASA Astrophysics Data System (ADS)

Ye, Junjian; Zhang, Qin; Li, Xianbo; Wang, Xianchen; Ke, Baolin; Li, Xianhai; Shen, Zhihui

2018-06-01

The adsorption of surfactants on a solid surface could alter its wettability, which offers a wide range of relevant applications such as mineral flotation, hydrophobic material preparation and nanomaterial dispersion. The morphology of adsorbed oleate on a collophane surface was visualized using the peakforce tapping mode of atomic force microscopy (AFM), and its effect on the wettability of collophane was analysed by contact angle measurements, adsorption measurements and molecular dynamics (MD) simulations. The AFM images demonstrated that the adsorbed structure varied with different oleate concentrations. First, the small cylindrical micelles with concomitant monolayer and bilayer structures were observed above the hemimicelle concentration (hmc) of 1 × 10-5 mol/L, which enhanced the hydrophobicity of the collophane surface, and the collophane surface was not completely covered with the oleate monolayer due to surface heterogeneity. Then, large cylindrical micelles with a major bilayer were formed as the critical micelle concentration (cmc) of 1 × 10-3 mol/L was approached, which decreased its hydrophobicity, and finally the formation of large cylindrical micelles with multilayer at the cmc caused the hydrophilicity of the collophane surface. Therefore, there was a suitable equilibrium concentration between the hmc and cmc for oleate as a collector during mineral flotation, and oleate could also be used as a dispersant for colloidal stability when its equilibrium concentration reached the cmc. The effect of the adsorbed structure on the wettability of collophane was also confirmed by MD simulations. This study provides a good understanding of the surface modification of particles by surfactants for flotation and dispersion applications.

Efficient adsorption of Au(CN)2- from gold cyanidation with graphene oxide-polyethylenimine hydrogel as adsorbent

NASA Astrophysics Data System (ADS)

Yang, Lang; Jia, Feifei; Yang, Bingqiao; Song, Shaoxian

The adsorption of gold cyanide complex ion (Au(CN)2-) on graphene oxide-polyethylenimine hydrogel (GO/PEI hydrogel) from gold cyanidation has been studied to explore the possibility of the application of GO/PEI hydrogel in gold cyanidation process for extracting gold from ores. The adsorption was carried out in artificial Au(CN)2- aqueous solution with GO/PEI hydrogel as adsorbent. The experimental results, as well as IR, XPS and SEM-EDS, have shown that GO/PEI hydrogel exhibited a high adsorption capacity and a fast adsorption rate of Au(CN)2-, suggesting that GO/PEI hydrogel might be a good adsorbent for the recovery of Au(CN)2-. The adsorption of Au(CN)2- on GO/PEI hydrogel obeyed the Langmuir isotherm model and fitted well with the pseudo second order model. The good recovery of Au(CN)2- was largely related to the porous structure, large specific surface area, as well as the oxygenous functional groups on the surface of GO/PEI hydrogel.

Evaluation of Flush-Mounted, S-Duct Inlets With Large Amounts of Boundary Layer Ingestion

NASA Technical Reports Server (NTRS)

Berrier, Bobby L.; Morehouse, Melissa B.

2003-01-01

A new high Reynolds number test capability for boundary layer ingesting inlets has been developed for the NASA Langley Research Center 0.3-Meter Transonic Cryogenic Tunnel. Using this new capability, an experimental investigation of four S-duct inlet configurations with large amounts of boundary layer ingestion (nominal boundary layer thickness of about 40% of inlet height) was conducted at realistic operating conditions (high subsonic Mach numbers and full-scale Reynolds numbers). The objectives of this investigation were to 1) develop a new high Reynolds number, boundary-layer ingesting inlet test capability, 2) evaluate the performance of several boundary layer ingesting S-duct inlets, 3) provide a database for CFD tool validation, and 4) provide a baseline inlet for future inlet flow-control studies. Tests were conducted at Mach numbers from 0.25 to 0.83, Reynolds numbers (based on duct exit diameter) from 5.1 million to a fullscale value of 13.9 million, and inlet mass-flow ratios from 0.39 to 1.58 depending on Mach number. Results of this investigation indicate that inlet pressure recovery generally decreased and inlet distortion generally increased with increasing Mach number. Except at low Mach numbers, increasing inlet mass-flow increased pressure recovery and increased distortion. Increasing the amount of boundary layer ingestion (by decreasing inlet throat height and increasing inlet throat width) or ingesting a boundary layer with a distorted profile decreased pressure recovery and increased distortion. Finally, increasing Reynolds number had almost no effect on inlet distortion but increased inlet recovery by about one-half percent at a Mach number near cruise.

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.

[Effects of various adsorbants on coagulation factors (author's transl)].

PubMed

Soulier, J P; Prou-Wartelle, O

1975-01-01

Adsorption of clotting factors by various adsorbants is studied (tricalcium phosphate, baryum sulfate or carbonate or citrate, calcium oxalate, aluminium hydroxyde and several silicate such as: kaolin, celite, bentonite, attapulgite, beidellite, asbestos). The main properties of each adsorbant are listed as well as several applications such as: selective adsorption of fibrinogen, separation between fibrinogen and factor VIII, separation of factor II from the other components of the prothrombin complex. Activation of factors XII and XI by the various silicates, as well as the activation of factor V by attapulgite are studied. Finally, the action of such adsorbants on the fibrinolytic system is summarized.

Application of advanced sampling and analysis methods to predict the structure of adsorbed protein on a material surface

PubMed Central

Abramyan, Tigran M.; Hyde-Volpe, David L.; Stuart, Steven J.; Latour, Robert A.

2017-01-01

The use of standard molecular dynamics simulation methods to predict the interactions of a protein with a material surface have the inherent limitations of lacking the ability to determine the most likely conformations and orientations of the adsorbed protein on the surface and to determine the level of convergence attained by the simulation. In addition, standard mixing rules are typically applied to combine the nonbonded force field parameters of the solution and solid phases the system to represent interfacial behavior without validation. As a means to circumvent these problems, the authors demonstrate the application of an efficient advanced sampling method (TIGER2A) for the simulation of the adsorption of hen egg-white lysozyme on a crystalline (110) high-density polyethylene surface plane. Simulations are conducted to generate a Boltzmann-weighted ensemble of sampled states using force field parameters that were validated to represent interfacial behavior for this system. The resulting ensembles of sampled states were then analyzed using an in-house-developed cluster analysis method to predict the most probable orientations and conformations of the protein on the surface based on the amount of sampling performed, from which free energy differences between the adsorbed states were able to be calculated. In addition, by conducting two independent sets of TIGER2A simulations combined with cluster analyses, the authors demonstrate a method to estimate the degree of convergence achieved for a given amount of sampling. The results from these simulations demonstrate that these methods enable the most probable orientations and conformations of an adsorbed protein to be predicted and that the use of our validated interfacial force field parameter set provides closer agreement to available experimental results compared to using standard CHARMM force field parameterization to represent molecular behavior at the interface. PMID:28514864

Deformability of adsorbents during adsorption and principles of the thermodynamics of solid-phase systems

NASA Astrophysics Data System (ADS)

Tovbin, Yu. K.

2017-09-01

A microscopic theory of adsorption, based on a discrete continuum lattice gas model for noninert (including deformable) adsorbents that change their lattice parameters during adsorption, is presented. Cases of the complete and partial equilibrium states of the adsorbent are considered. In the former, the adsorbent consists of coexisting solid and vapor phases of adsorbent components, and the adsorbate is a mobile component of the vapor phase with an arbitrary density (up to that of the liquid adsorbate phase). The adsorptive transitioning to the bound state changes the state of the near-surface region of the adsorbent. In the latter, there are no equilibrium components of the adsorbent between the solid and vapor phases. The adsorbent state is shown to be determined by its prehistory, rather than set by chemical potentials of vapor of its components. Relations between the microscopic theory and thermodynamic interpretations are discussed: (1) adsorption on an open surface, (2) two-dimensional stratification of the adsorbate mobile phase on an open homogeneous surface, (3) small microcrystals in vacuum and the gas phase, and (4) adsorption in porous systems.

Generation Expansion Planning With Large Amounts of Wind Power via Decision-Dependent Stochastic Programming

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

Zhan, Yiduo; Zheng, Qipeng P.; Wang, Jianhui

Power generation expansion planning needs to deal with future uncertainties carefully, given that the invested generation assets will be in operation for a long time. Many stochastic programming models have been proposed to tackle this challenge. However, most previous works assume predetermined future uncertainties (i.e., fixed random outcomes with given probabilities). In several recent studies of generation assets' planning (e.g., thermal versus renewable), new findings show that the investment decisions could affect the future uncertainties as well. To this end, this paper proposes a multistage decision-dependent stochastic optimization model for long-term large-scale generation expansion planning, where large amounts of windmore » power are involved. In the decision-dependent model, the future uncertainties are not only affecting but also affected by the current decisions. In particular, the probability distribution function is determined by not only input parameters but also decision variables. To deal with the nonlinear constraints in our model, a quasi-exact solution approach is then introduced to reformulate the multistage stochastic investment model to a mixed-integer linear programming model. The wind penetration, investment decisions, and the optimality of the decision-dependent model are evaluated in a series of multistage case studies. The results show that the proposed decision-dependent model provides effective optimization solutions for long-term generation expansion planning.« less

Development of the Molecular Adsorber Coating for Spacecraft and Instrument Interiors

NASA Technical Reports Server (NTRS)

Abraham, Nithin

2011-01-01

On-orbit Molecular Contamination occurs when materials outgas and deposit onto very sensitive interior surfaces of the spacecraft and instruments. The current solution, Molecular Adsorber Pucks, has disadvantages, which are reviewed. A new innovative solution, Molecular Adsorber Coating (MAC), is currently being formulated, optimized, and tested. It is a sprayable alternative composed of Zeolite-based coating with adsorbing properties.

Storm impacts upon the composition of organic matrices in Nagara River--a study based on molecular weight and activated carbon adsorbability.

PubMed

Li, Fusheng; Yuasa, Akira; Chiharada, Hajime; Matsui, Yoshihiko

2003-09-01

The impacts of a heavy storm of rain on the composition of natural organic matter (NOM) in Nagara River water were studied in terms of molecular weights (MWs) and activated carbon (AC) adsorbabilities using six water samples collected during a critical Typhoon weather condition. The composition in MWs was analyzed using a HPSEC system and that in adsorbabilities was characterized using parameters devised to reflect NOMs average adsorptive strength (K(M)), adsorptive strength polydispersity (sigma), affinity to AC (1/n) and non-adsorbable fraction (C(non)/C(T0)), respectively. These parameters were determined by model description of observed isotherms with a distributed fictive component method. The heavy storm of rain brought higher content of larger organic components into the river source, thus causing changes of NOMs weight-averaged MWs in the range of 2962-3495 Dalton and MW polydispersity in the narrow range of 1.153-1.226. Comparison of K(M) and sigma values for all samples assessed with both indices of TOC and UV260 showed that large proportions of the storm-induced organic components had adsorptive strengths similar to those existent before the storm, with the presence levels for components revealing much strong and weak adsorbabilities being low. Among all organic components brought into the river by the storm of rain, the percentages of non-adsorbable ones was lower (smaller C(non)/C(T0) values); and the adsorbable ones had generally more affinity to the adsorbents used (smaller 1/n values).

Structural properties of atactic polystyrene adsorbed onto solid surfaces.

PubMed

Tatek, Yergou B; Tsige, Mesfin

2011-11-07

In the present work, we are studying the local conformation of chains in a thin film of polystyrene adsorbed on a solid substrate by using atomistically detailed simulations. The simulations are carried out by using the readily available and massively parallel molecular dynamics code known as LAMMPS. In particular, a special emphasis is given to the density and orientation of side chains (which consist of phenyl groups and methylene units) at solid/polymer and polymer/vacuum interfaces. Three types of substrates were used in our study: α-quartz, graphite, and amorphous silica. Our investigation was restricted to atactic polystyrene. Our results show that the density and structural properties of side chains depend on the type of surface. An excess of phenyl rings is observed near the α-quartz substrate while the film adsorbed on graphite is depleted in C(6)H(5). Moreover, the orientation of the rings and methylene units on the substrate/film interface show a strong dependence on the type of the substrate, while the rings at the film/vacuum interface show a marked tendency to point outward, away from the film. The results we obtained are in a large part in good agreement with previous experimental and simulation results.

Investigations into Alternative Desorption Agents for Amidoxime-Based Polymeric Uranium Adsorbents

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

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

2015-06-01

Amidoxime-based polymeric braid adsorbents that can extract uranium (U) from seawater are being developed to provide a sustainable supply of fuel for nuclear reactors. A critical step in the development of the technology is to develop elution procedures to selectively remove U from the adsorbents and to do so in a manner that allows the adsorbent material to be reused. This study investigates use of high concentrations of bicarbonate along with targeted chelating agents as an alternative means to the mild acid elution procedures currently in use for selectively eluting uranium from amidoxime-based polymeric adsorbents.

Semantic interoperability challenges to process large amount of data perspectives in forensic and legal medicine.

PubMed

Jaulent, Marie-Christine; Leprovost, Damien; Charlet, Jean; Choquet, Remy

2018-07-01

This article is a position paper dealing with semantic interoperability challenges. It addresses the Variety and Veracity dimensions when integrating, sharing and reusing large amount of heterogeneous data for data analysis and decision making applications in the healthcare domain. Many issues are raised by the necessity to conform Big Data to interoperability standards. We discuss how semantics can contribute to the improvement of information sharing and address the problem of data mediation with domain ontologies. We then introduce the main steps for building domain ontologies as they could be implemented in the context of Forensic and Legal medicine. We conclude with a particular emphasis on the current limitations in standardisation and the importance of knowledge formalization. Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Cadmium telluride nanoparticles loaded on activated carbon as adsorbent for removal of sunset yellow

NASA Astrophysics Data System (ADS)

Ghaedi, M.; Hekmati Jah, A.; Khodadoust, S.; Sahraei, R.; Daneshfar, A.; Mihandoost, A.; Purkait, M. K.

2012-05-01

Adsorption is a promising technique for decolorization of effluents of textile dyeing industries but its application is limited due to requirement of high amounts of adsorbent required. The objective of this study was to assess the potential of cadmium telluride nanoparticles loaded onto activated carbon (CdTN-AC) for the removal of sunset yellow (SY) dye from aqueous solution. Adsorption studies were conducted in a batch mode varying solution pH, contact time, initial dye concentration, CdTN-AC dose, and temperature. In order to investigate the efficiency of SY adsorption on CdTN-AC, pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion kinetic models were studied. It was observed that the pseudo-second-order kinetic model fits better than other kinetic models with good correlation coefficient. Equilibrium data were fitted to the Langmuir model. Thermodynamic parameters such as enthalpy, entropy, activation energy, and sticking probability were also calculated. It was found that the sorption of SY onto CdTN-AC was spontaneous and endothermic in nature. The proposed adsorbent is applicable for SY removal from waste of real effluents including pea-shooter, orange drink and jelly banana with efficiency more than 97%.

STM observation of the chemical reaction of atomic hydrogen on the N-adsorbed Cu(001) surface

NASA Astrophysics Data System (ADS)

Hattori, Takuma; Yamada, Masamichi; Komori, Fumio

2017-01-01

Chemical reaction of atomic hydrogen with the N-adsorbed Cu(001) surfaces was investigated at room temperature by scanning tunnel microscopy. At the low exposure of atomic hydrogen, it reacted with the N atoms and turned to be the NH species on the surface. The reaction rate is proportional to the amount of the unreacted N atoms. By increasing the exposure of atomic hydrogen from this condition, the amount of nitrogen species on the surface decreased. This is attributed to the formation of ammonia and its desorption from the surface. The NH species on the surface turn to NH3 through the surface NH2 species by atomic hydrogen. Coexistence of the clean Cu surface enhances the rate of ammonia formation owing to atomic hydrogen migrating on the clean surface.

Highly effective removal of mercury and lead ions from wastewater by mercaptoamine-functionalised silica-coated magnetic nano-adsorbents: Behaviours and mechanisms

NASA Astrophysics Data System (ADS)

Bao, Shuangyou; Li, Kai; Ning, Ping; Peng, Jinhui; Jin, Xu; Tang, Lihong

2017-01-01

A novel hybrid material was fabricated using mercaptoamine-functionalised silica-coated magnetic nanoparticles (MAF-SCMNPs) and was effective in the extraction and recovery of mercury and lead ions from wastewater. The properties of this new magnetic material were explored using various characterisation and analysis methods. Adsorbent amounts, pH levels and initial concentrations were optimised to improve removal efficiency. Additionally, kinetics, thermodynamics and adsorption isotherms were investigated to determine the mechanism by which the fabricated MAF-SCMNPs adsorb heavy metal ions. The results revealed that MAF-SCMNPs were acid-resistant. Sorption likely occurred by chelation through the amine group and ion exchange between heavy metal ions and thiol functional groups on the nanoadsorbent surface. The equilibrium was attained within 120 min, and the adsorption kinetics showed pseudo-second-order (R2 > 0.99). The mercury and lead adsorption isotherms were in agreement with the Freundlich model, displaying maximum adsorption capacities of 355 and 292 mg/g, respectively. The maximum adsorptions took place at pH 5-6 and 6-7 for Hg(II) and Pb(II), respectively. The maximum adsorptions were observed at 10 mg and 12 mg adsorbent quantities for Hg(II) and Pb(II), respectively. The adsorption process was endothermic and spontaneous within the temperature range of 298-318 K. This work demonstrates a unique magnetic nano-adsorbent for the removal of Hg(II) and Pb(II) from wastewater.

Formic Acid Dissociative Adsorption on NiO(111): Energetics and Structure of Adsorbed Formate

DOE PAGES

Zhao, Wei; Doyle, Andrew D.; Morgan, Sawyer E.; ...

2017-11-21

Here, the dissociative adsorption of carboxylic acids on oxide surfaces is important for understanding adsorbed carboxylates, which are important as intermediates in catalytic reactions, for the organo-functionalization of oxide surfaces, and in many other aspects of oxide surface chemistry. We present here the first direct experimental measurement of the heat of dissociative adsorption of any carboxylic acid on any single-crystal oxide surface. The enthalpy of the dissociative adsorption of formic acid, the simplest carboxylic acid, to produce adsorbed formate and hydrogen (as a surface hydroxyl) on a (2 × 2)-NiO(111) surface is measured by single crystal adsorption calorimetry. The differentialmore » heat of adsorption decreases with formic acid coverage from 202 to 99 kJ/mol at saturation (0.25 ML). The structure of the adsorbed products is clarified by density functional theory (DFT) calculations, which provide energies in reasonable agreement with the calorimetry. These calculations show that formic acid readily dissociates on both the oxygen and Ni terminations of the octapolar NiO(111) surfaces, donating its acid H to a surface lattice oxygen, while HCOO adsorbs preferentially with bridging-type geometry near the M-O 3/O-M 3 sites. The calculated energetics at low coverages agrees well with experimental data, while larger differences are observed at high coverage (0.25 ML). The large decrease in experimental heat of adsorption with coverage can be brought into agreement with the DFT energies if we assume that both types of octapolar surface terminations (O- and Ni-) are present on the starting surface.« less

Formic Acid Dissociative Adsorption on NiO(111): Energetics and Structure of Adsorbed Formate

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

Zhao, Wei; Doyle, Andrew D.; Morgan, Sawyer E.

Here, the dissociative adsorption of carboxylic acids on oxide surfaces is important for understanding adsorbed carboxylates, which are important as intermediates in catalytic reactions, for the organo-functionalization of oxide surfaces, and in many other aspects of oxide surface chemistry. We present here the first direct experimental measurement of the heat of dissociative adsorption of any carboxylic acid on any single-crystal oxide surface. The enthalpy of the dissociative adsorption of formic acid, the simplest carboxylic acid, to produce adsorbed formate and hydrogen (as a surface hydroxyl) on a (2 × 2)-NiO(111) surface is measured by single crystal adsorption calorimetry. The differentialmore » heat of adsorption decreases with formic acid coverage from 202 to 99 kJ/mol at saturation (0.25 ML). The structure of the adsorbed products is clarified by density functional theory (DFT) calculations, which provide energies in reasonable agreement with the calorimetry. These calculations show that formic acid readily dissociates on both the oxygen and Ni terminations of the octapolar NiO(111) surfaces, donating its acid H to a surface lattice oxygen, while HCOO adsorbs preferentially with bridging-type geometry near the M-O 3/O-M 3 sites. The calculated energetics at low coverages agrees well with experimental data, while larger differences are observed at high coverage (0.25 ML). The large decrease in experimental heat of adsorption with coverage can be brought into agreement with the DFT energies if we assume that both types of octapolar surface terminations (O- and Ni-) are present on the starting surface.« less

PERVAPORATION USING ADSORBENT-FILLED MEMBRANES

EPA Science Inventory

Membranes containing selective fillers, such as zeolites and activated carbon, can improve the separation by pervaporation. Applications of adsorbent-filled membranes in pervaporation have been demonstrated by a number of studies. These applications include removal of organic co...

Sorption of lead from aqueous solution by chemically modified carbon adsorbents.

PubMed

Nadeem, Muhammad; Mahmood, A; Shahid, S A; Shah, S S; Khalid, A M; McKay, G

2006-12-01

An indigenously prepared, steam activated and chemically modified carbon from husk and pods of Moringa oleifera (M. oleifera), an agricultural waste, was comparatively examined as an adsorbent for the removal of lead from aqueous solutions. Studies were conducted as a function of contact time, initial metal concentration, dose of adsorbent, agitation speed, particle size and pH. Maximum uptake capacities were found to be, 98.89, 96.58, 91.8, 88.63, 79.43% for cetyltrimethyl ammonium bromide (CTAB), phosphoric, sulfuric, hydrochloric acid treated and untreated carbon adsorbents, respectively. Bangham, pseudo-first- and second-order, intra-particle diffusion equations were implemented to express the sorption mechanism by utilized adsorbents. Adsorption rate of lead ions was found to be considerably faster for chemically modified adsorbents than unmodified. The results of adsorption were fitted to both the Langmuir and Freundlich models. Satisfactory agreement between the metal uptake capacities by the adsorbents at different time intervals was expressed by the correlation coefficient (R(2)). The Langmuir model represented the sorption process better than the Freundlich one, with R(2) values ranging from 0.994 to 0.998.

Process for producing an activated carbon adsorbent with integral heat transfer apparatus

NASA Technical Reports Server (NTRS)

Jones, Jack A. (Inventor); Yavrouian, Andre H. (Inventor)

1996-01-01

A process for producing an integral adsorbent-heat exchanger apparatus useful in ammonia refrigerant heat pump systems. In one embodiment, the process wets an activated carbon particles-solvent mixture with a binder-solvent mixture, presses the binder wetted activated carbon mixture on a metal tube surface and thereafter pyrolyzes the mixture to form a bonded activated carbon matrix adjoined to the tube surface. The integral apparatus can be easily and inexpensively produced by the process in large quantities.

Formulation of an alginate-vineyard pruning waste composite as a new eco-friendly adsorbent to remove micronutrients from agroindustrial effluents.

PubMed

Vecino, X; Devesa-Rey, R; Moldes, A B; Cruz, J M

2014-09-01

The cellulosic fraction of vineyard pruning waste (free of hemicellulosic sugars) was entrapped in calcium alginate beads and evaluated as an eco-friendly adsorbent for the removal of different nutrients and micronutrients (Mg, P, Zn, K, N-NH4, SO4, TN, TC and PO4) from an agroindustrial effluent (winery wastewater). Batch adsorption studies were performed by varying the amounts of cellulosic adsorbent (0.5-2%), sodium alginate (1-5%) and calcium chloride (0.05-0.9M) included in the biocomposite. The optimal formulation of the adsorbent composite varied depending on the target contaminant. Thus, for the adsorption of cationic contaminants (Mg, Zn, K, N-NH4 and TN), the best mixture comprised 5% sodium alginate, 0.05M calcium chloride and 0.5% cellulosic vineyard pruning waste, whereas for removal of anionic compounds (P, SO4 and PO4), the optimal mixture comprised 1% sodium alginate, 0.9M calcium chloride and 0.5% cellulosic vineyard pruning waste. To remove TC from the winery wastewater, the optimal mixture comprised 3% of sodium alginate, 0.475M calcium chloride and 0.5% cellulosic vineyard pruning waste. Copyright © 2014 Elsevier Ltd. All rights reserved.

EFFECT OF SIMULATED SULFURIC ACID RAIN ON THE CHEMISTRY OF A SULFATE-ADSORBING FOREST SOIL

EPA Science Inventory

Simulated H2SO4 rain (pH 3.0, 3.5, 4.0) or control rain (pH 5.6) was applied for 3.5 yr to large lysimeter boxes containing a sulfate-adsorbing forest soil and either red alder (Alnus rubra) or sugar maple (Acer saccharum) seedlings. After removal of the plants and the litter lay...

Internal Reflection Spectra of Surface Compounds and Adsorbed Molecules

NASA Astrophysics Data System (ADS)

Zolotarev, V. M.; Lygin, V. I.; Tarasevich, B. N.

1981-01-01

The application of attenuated total reflection (ATR) spectroscopy in surface studies of inorganic adsorbents and catalysts, polymers, and optically transparent electrodes is discussed. The basic principles of ATR spectroscopy as applied to surface phenomena are considered, with special reference to thin films, industrial adsorbents and catalysts, and polymer degradation processes. 276 references.

Removal of dieldrin from aqueous solution by a novel triolein-embedded composite adsorbent.

PubMed

Ru, Jia; Liu, Huijuan; Qu, Jiuhui; Wang, Aimin; Dai, Ruihua

2007-03-06

In this study, a novel triolein-embedded activated carbon composite adsorbent (CA-T) was prepared and applied for the adsorption and removal of dieldrin from aqueous systems. Experiments were carried out to investigate the adsorption behavior of dieldrin on CA-T, including adsorption isotherms, adsorption kinetics, the influence of initial concentration, temperature, shaking speed, pH and the addition of humic acid (HA) on adsorption. The adsorption isotherms accorded with Freundlich equation. Three kinetics models, including pseudo-first-order, pseudo-second-order and intraparticle diffusion models, were used to fit the experimental data. By comparing the correlation coefficients, it was found that both pseudo-second-order and intraparticle diffusion models were used to well describe the adsorption of dieldrin on CA-T. The addition of HA had little effect on dieldrin adsorption by CA-T. Results indicated that CA-T appeared to be a promising adsorbent for removing lipophilic dieldrin in trace amount, which was advantageous over pure granular activated carbon (GAC). The adsorption rate increased with increasing shaking speed, initial concentration and temperature, and remained almost unchanged in the pH range of 4-8. Thermodynamic calculations indicated that the adsorption reaction was spontaneous with a high affinity and the adsorption was an endothermic reaction.

Determination of Adsorption Capacity and Kinetics of Amidoxime-Based Uranium Adsorbent Braided Material in Unfiltered Seawater Using a Flume Exposure System

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

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

days. The amount of biomass increase retained by the adsorbent in the dark flume was only a quarter of that observed in the light-exposed flume. Biofouling in sunlit surface seawater has the potential to reduce uranium adsorption capacity by ~30% after 42 days of exposure. Minimal or no adsorption loss due to biofouling occurred in the dark flume exposure. Attempts to assess time series measurements of uranium adsorption capacity using “snips” off a master braid are fraught with problems due to the inability to easily determine the mass of the adsorbent material when the biofouling is present. The ability to determine the adsorption of biogenically important trace elements (e.g. Fe, Mn, Zn, Cu, and Sr) on biofouled adsorbents is also problematic.« less

Application of low-cost adsorbents for dye removal--a review.

PubMed

Gupta, V K; Suhas

2009-06-01

Dyes are an important class of pollutants, and can even be identified by the human eye. Disposal of dyes in precious water resources must be avoided, however, and for that various treatment technologies are in use. Among various methods adsorption occupies a prominent place in dye removal. The growing demand for efficient and low-cost treatment methods and the importance of adsorption has given rise to low-cost alternative adsorbents (LCAs). This review highlights and provides an overview of these LCAs comprising natural, industrial as well as synthetic materials/wastes and their application for dyes removal. In addition, various other methods used for dye removal from water and wastewater are also complied in brief. From a comprehensive literature review, it was found that some LCAs, in addition to having wide availability, have fast kinetics and appreciable adsorption capacities too. Advantages and disadvantages of adsorbents, favourable conditions for particular adsorbate-adsorbent systems, and adsorption capacities of various low-cost adsorbents and commercial activated carbons as available in the literature are presented. Conclusions have been drawn from the literature reviewed, and suggestions for future research are proposed.

Interactions of organic contaminants with mineral-adsorbed surfactants

USGS Publications Warehouse

Zhu, L.; Chen, B.; Tao, S.; Chiou, C.T.

2003-01-01

Sorption of organic contaminants (phenol, p-nitrophenol, and naphthalene) to natural solids (soils and bentonite) with and without myristylpyridinium bromide (MPB) cationic surfactant was studied to provide novel insight to interactions of contaminants with the mineral-adsorbed surfactant. Contaminant sorption coefficients with mineral-adsorbed surfactants, Kss, show a strong dependence on surfactant loading in the solid. At low surfactant levels, the Kss values increased with increasing sorbed surfactant mass, reached a maximum, and then decreased with increasing surfactant loading. The Kss values for contaminants were always higher than respective partition coefficients with surfactant micelles (Kmc) and natural organic matter (Koc). At examined MPB concentrations in water the three organic contaminants showed little solubility enhancement by MPB. At low sorbed-surfactant levels, the resulting mineral-adsorbed surfactant via the cation-exchange process appears to form a thin organic film, which effectively "adsorbs" the contaminants, resulting in very high Kss values. At high surfactant levels, the sorbed surfactant on minerals appears to form a bulklike medium that behaves essentially as a partition phase (rather than an adsorptive surface), with the resulting Kss being significantly decreased and less dependent on the MPB loading. The results provide a reference to the use of surfactants for remediation of contaminated soils/sediments or groundwater in engineered surfactant-enhanced washing.

Preparation and characterization of a novel adsorbent from Moringa oleifera leaf

NASA Astrophysics Data System (ADS)

Bello, Olugbenga Solomon; Adegoke, Kayode Adesina; Akinyunni, Opeyemi Omowumi

2017-06-01

A new and novel adsorbent was obtained by impregnation of Moringa oleifera leaf in H2SO4 and NaOH, respectively. Prepared adsorbents were characterized using elemental analysis, FT-IR, SEM, TGA and EDX analyses, respectively. The effects of operational parameters, such as pH, moisture content, ash content, porosity and iodine number on these adsorbents were investigated and compared with those of commercial activated carbon (CAC). EDX results of acid activated M. oleifera leaf have the highest percentage of carbon by weight (69.40 %) and (76.11 %) by atom, respectively. Proximate analysis showed that the fixed carbon content of acid activated M. oleifera leaf (69.14 ± 0.01) was the highest of all adsorbents studied. Conclusively, the present investigation shows that acid activated M. oleifera leaf is a good alternative adsorbent that could be used in lieu of CAC for recovery of dyes and heavy metal from aqueous solutions and other separation techniques.

An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid

EPA Science Inventory

Zinc oxide (ZnO)-coated zeolite adsorbents were developed by both nitric acid modification and Zn(NO3)2•6H2O functionalization of zeolite. The developed adsorbents were used for the removal of humic acid (HA) from aqueous solutions. The adsorption capacity of the adsorbents at 21...

Multi-pesticides residue analysis of grains using modified magnetic nanoparticle adsorbent for facile and efficient cleanup.

PubMed

Liu, Zhenzhen; Qi, Peipei; Wang, Xiangyun; Wang, Zhiwei; Xu, Xiahong; Chen, Wenxue; Wu, Liyu; Zhang, Hu; Wang, Qiang; Wang, Xinquan

2017-09-01

A facile, rapid sample pretreatment method was developed based on magnetic nanoparticles for multi-pesticides residue analysis of grains. Magnetite (Fe 3 O 4 ) nanoparticles modified with 3-(N,N-diethylamino)propyltrimethoxysilane (Fe 3 O 4 -PSA) and commercial C18 were selected as the cleanup adsorbents to remove the target interferences of the matrix, such as fatty acids and non-polar compounds. Rice was used as the representative grain sample for method optimization. The amount of Fe 3 O 4 -PSA and C18 were systematically investigated for selecting the suitable purification conditions, and the simultaneous determination of 50 pesticides and 8 related metabolites in rice was established by liquid chromatography-tandem mass spectrometry. Under the optimal conditions, the method validation was performed including linearity, sensitivity, matrix effect, recovery and precision, which all satisfy the requirement for pesticides residue analysis. Compared to the conventional QuEChERS method with non-magnetic material as cleanup adsorbent, the present method can save 30% of the pretreatment time, giving the high throughput analysis possible. Copyright © 2017 Elsevier Ltd. All rights reserved.

Unusual Entropy of Adsorbed Methane on Zeolite-Templated Carbon

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

Stadie, Nicholas P.; Murialdo, Maxwell; Ahn, Channing C.

2015-11-25

Methane adsorption at high pressures and across a wide range of temperatures was investigated on the surface of three porous carbon adsorbents with complementary structural properties. The measured adsorption equilibria were analyzed using a method that can accurately account for nonideal fluid properties and distinguish between absolute and excess quantities of adsorption, and that also allows the direct calculation of the thermodynamic potentials relevant to adsorption. On zeolite-templated carbon (ZTC), a material that exhibits extremely high surface area with optimal pore size and homogeneous structure, methane adsorption occurs with unusual thermodynamic properties that are greatly beneficial for deliverable gas storage:more » an enthalpy of adsorption that increases with site occupancy, and an unusually low entropy of the adsorbed phase. The origin of these properties is elucidated by comparison of the experimental results with a statistical mechanical model. The results indicate that temperature-dependent clustering (i.e., reduced configurations) of the adsorbed phase due to enhanced lateral interactions can account for the peculiarities of methane adsorbed on ZTC.« less

Simulations of noble gases adsorbed on graphene

NASA Astrophysics Data System (ADS)

Maiga, Sidi; Gatica, Silvina

2014-03-01

We present results of Grand Canonical Monte Carlo simulations of adsorption of Kr, Ar and Xe on a suspended graphene sheet. We compute the adsorbate-adsorbate interaction by a Lennard-Jones potential. We adopt a hybrid model for the graphene-adsorbate force; in the hybrid model, the potential interaction with the nearest carbon atoms (within a distance rnn) is computed with an atomistic pair potential Ua; for the atoms at r>rnn, we compute the interaction energy as a continuous integration over a carbon uniform sheet with the density of graphene. For the atomistic potential Ua, we assume the anisotropic LJ potential adapted from the graphite-He interaction proposed by Cole et.al. This interaction includes the anisotropy of the C atoms on graphene, which originates in the anisotropic π-bonds. The adsorption isotherms, energy and structure of the layer are obtained and compared with experimental results. We also compare with the adsorption on graphite and carbon nanotubes. This research was supported by NSF/PRDM (Howard University) and NSF (DMR 1006010).

Development of porous structured polyvinyl alcohol/zeolite/carbon composites as adsorbent

NASA Astrophysics Data System (ADS)

Laksmono, J. A.; Sudibandriyo, M.; Saputra, A. H.; Haryono, A.

2017-05-01

Adsorption is a separation process that has higher energy efficiency than others. Analyzing the nature of the adsorbate and the selection of suitable adsorbent are key success in adsorption. The performance of the adsorbent can be modified either physically or chemically to obtain the efficiency and effectiveness of the adsorption, this can be facilitated by using a composite adsorbent. In this study, we have conducted the preparation process of a polyvinyl alcohol (PVA)/zeolite/carbon composites. The resulting adsorbent composites are dedicated for ethanol - water dehydration proposes. The composites were prepared using cross-linked polymerization method followed by supercritical fluid extraction (SFE) to obtain the porous structured upon drying process. The characterization of the functional groups and morphology were performed by using Fourier Transform Infra-Red (FTIR) and Scanning Electron Microscopy (SEM), respectively. The FTIR analysis showed that composite prepared by SFE method formed hydrogen bonding confirmed by the appearance of peaks at 2950 - 3000 cm-1 compared to composite without SFE method, whereas, the results of SEM study showed the formation of three layered structures. On basis of the obtained results, it can be shown that PVA/zeolite/carbon has high potential to be develop further as an adsorbent composite.

Analysis of Adsorbate-Adsorbate and Adsorbate-Adsorbent Interactions to Decode Isosteric Heats of Gas Adsorption.

PubMed

Madani, S Hadi; Sedghi, Saeid; Biggs, Mark J; Pendleton, Phillip

2015-12-21

A qualitative interpretation is proposed to interpret isosteric heats of adsorption by considering contributions from three general classes of interaction energy: fluid-fluid heat, fluid-solid heat, and fluid-high-energy site (HES) heat. Multiple temperature adsorption isotherms are defined for nitrogen, T=(75, 77, 79) K, argon at T=(85, 87, 89) K, and for water and methanol at T=(278, 288, 298) K on a well-characterized polymer-based, activated carbon. Nitrogen and argon are subjected to isosteric heat analyses; their zero filling isosteric heats of adsorption are consistent with slit-pore, adsorption energy enhancement modelling. Water adsorbs entirely via specific interactions, offering decreasing isosteric heat at low pore filling followed by a constant heat slightly in excess of water condensation enthalpy, demonstrating the effects of micropores. Methanol offers both specific adsorption via the alcohol group and non-specific interactions via its methyl group; the isosteric heat increases at low pore filling, indicating the predominance of non-specific interactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Expert system shell to reason on large amounts of data

NASA Technical Reports Server (NTRS)

Giuffrida, Gionanni

1994-01-01

The current data base management systems (DBMS's) do not provide a sophisticated environment to develop rule based expert systems applications. Some of the new DBMS's come with some sort of rule mechanism; these are active and deductive database systems. However, both of these are not featured enough to support full implementation based on rules. On the other hand, current expert system shells do not provide any link with external databases. That is, all the data are kept in the system working memory. Such working memory is maintained in main memory. For some applications the reduced size of the available working memory could represent a constraint for the development. Typically these are applications which require reasoning on huge amounts of data. All these data do not fit into the computer main memory. Moreover, in some cases these data can be already available in some database systems and continuously updated while the expert system is running. This paper proposes an architecture which employs knowledge discovering techniques to reduce the amount of data to be stored in the main memory; in this architecture a standard DBMS is coupled with a rule-based language. The data are stored into the DBMS. An interface between the two systems is responsible for inducing knowledge from the set of relations. Such induced knowledge is then transferred to the rule-based language working memory.

Nanofiber adsorbents for high productivity continuous downstream processing.

PubMed

Hardick, Oliver; Dods, Stewart; Stevens, Bob; Bracewell, Daniel G

2015-11-10

An ever increasing focus is being placed on the manufacturing costs of biotherapeutics. The drive towards continuous processing offers one opportunity to address these costs through the advantages it offers. Continuous operation presents opportunities for real-time process monitoring and automated control with potential benefits including predictable product specification, reduced labour costs, and integration with other continuous processes. Specifically to chromatographic operations continuous processing presents an opportunity to use expensive media more efficiently while reducing their size and therefore cost. Here for the first time we show how a new adsorbent material (cellulosic nanofibers) having advantageous convective mass transfer properties can be combined with a high frequency simulated moving bed (SMB) design to provide superior productivity in a simple bioseparation. Electrospun polymeric nanofiber adsorbents offer an alternative ligand support surface for bioseparations. Their non-woven fiber structure with diameters in the sub-micron range creates a remarkably high surface area material that allows for rapid convective flow operations. A proof of concept study demonstrated the performance of an anion exchange nanofiber adsorbent based on criteria including flow and mass transfer properties, binding capacity, reproducibility and life-cycle performance. Binding capacities of the DEAE adsorbents were demonstrated to be 10mg/mL, this is indeed only a fraction of what is achievable from porous bead resins but in combination with a very high flowrate, the productivity of the nanofiber system is shown to be significant. Suitable packing into a flow distribution device has allowed for reproducible bind-elute operations at flowrates of 2,400 cm/h, many times greater than those used in typical beaded systems. These characteristics make them ideal candidates for operation in continuous chromatography systems. A SMB system was developed and optimised to

Mesoporous Silica Nanoparticles as an Adsorbent for Preconcentration and Determination of Trace Amount of Nickel in Environmental Samples by Atom Trap Flame Atomic Absorption Spectrometry

NASA Astrophysics Data System (ADS)

Shirkhanloo, H.; Falahnejad, M.; Zavvar Mousavi, H.

2016-01-01

A rapid enrichment method based on solid-phase extraction (SPE) has been established for preconcentration and separation of trace Ni(II) ions in water samples prior to their determination by atom trap flame atomic absorption spectrometry. A column filled with bulky NH2-UVM7 was used as the novel adsorbent. Under optimal conditions, the linear range, limit of detection (LOD), and preconcentration factor (PF) were 3-92 μg/L, 0.8 μg/L, and 100, respectively. The validity of the method was checked by the standard reference material.

Efficiency of basalt zeolite and Cuban zeolite to adsorb ammonia released from poultry litter.

PubMed

Nuernberg, Giselle B; Moreira, Marcelo A; Ernani, Paulo R; Almeida, Jaime A; Maciel, Tais M

2016-12-01

Confined poultry production is an important livestock activity, which generates large amounts of waste associated with the potential for environmental pollution and ammonia (NH 3 ) emissions. The release of ammonia negatively affects poultry production and decreases the N content of wastes that could be used as soil fertilizers. The objective of this study was to evaluate a low-cost, simple and rapid method to simulate ammonia emissions from poultry litter as well as to quantify the reduction in the ammonia emissions to the environment employing two adsorbent zeolites, a commercial Cuban zeolite (CZ) and a ground basalt Brazilian rock containing zeolite (BZ). The experiments were conducted in a laboratory, in 2012-2013. The zeolites were characterized by X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), physical adsorption of N 2 (BET) and scanning electron microscopy (SEM). Ammonia released from poultry litter and its simulation from NH 4 OH solution presented similar capture rates of 7.99 × 10 -5 and 7.35 × 10 -5  mg/h, respectively. Both zeolites contain SiO 2 and Al 2 O 3 as major constituents, with contents of 84% and 12% in the CZ, and 51% and 12% in the BZ, respectively, besides heulandite groups. Their BET surface areas were 89.4 and 11.3 m 2  g -1 , respectively, and the two zeolites had similar surface morphologies. The zeolites successfully adsorbed the ammonia released, but CZ was more efficient than BZ, since to capture all of the ammonia 5 g of CZ and 20 g of BZ were required. This difference is due to higher values for the superficial area, porosity, CEC and acid site strength of CZ relatively to BZ. The proposed methodology was shown to be an efficient method to simulate and quantify the ammonia released from poultry litter. Copyright © 2016 Elsevier Ltd. All rights reserved.

Preparation of amino acid-based polymer functionalized magnetic nanoparticles as adsorbents for analysis of plant growth regulators in bean sprouts.

PubMed

Ji, Shilei; Qi, Li; Li, Nan; Wang, Minglin

2016-09-01

A novel magnetic solid phase extraction (MSPE) adsorbent has been developed for enriching two plant growth regulators, including 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chlorophenoxyacetic acid (4-CPA), in bean sprouts. For preparing the MSPE adsorbent, poly(N-methacryloyl-L-phenylalanine methyl ester (P(MA-L-Phe-OMe)), amino acid-based polymer, was modified onto the magnetic nanoparticles via "grafting to" method by free radical polymerization. The resultant P(MA-L-Phe-OMe)-functionalized magnetic nanoparticles (Fe3O4@P(MA-L-Phe-OMe)) were characterized by Fourier transform infrared (FT-IR) spectroscopy and elemental analysis. The adsorption amount of Fe3O4@P(MA-L-Phe-OMe) nanoparticles to 2,4-D and 4-CPA were 39.82mgg(-1) and 29.02mgg(-1), respectively. Moreover, the prepared MSPE adsorbents showed good selectivity towards 2,4-D and 4-CPA due to the hydrophobic interactions and electrostatic forces between the target analytes and Fe3O4@P(MA-L-Phe-OMe). The results demonstrated that the proposed MSPE adsorbents have high affinity to the targets 2,4-D and 4-CPA. Under the optimized conditions, the proposed materials were successfully applied to enrich 2,4-D and 4-CPA in bean sprouts samples. The recovery values of the bean sprouts solution spiked the targets were from 90.9% to 96.4% with the relative standard deviations of 2.3-3.9%. Our work proved that the novel Fe3O4@P(MA-L-Phe-OMe) nanoparticles were the good adsorbents of magnetic solid phase extraction (MSPE) and have good potential for the analysis of trace compound in real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis of adsorbent from Tamarix hispida and modified by lanthanum metal for fluoride ions removal from wastewater: Adsorbent characteristics and real wastewater treatment data.

PubMed

Habibi, Nasim; Rouhi, Parham; Ramavandi, Bahman

2017-08-01

This data article describes a facile method for production of an adsorbent from Tamarix hispida wasted wood and modified by lanthanum metal for fluoride ions removal from wastewater. The main characteristics of the adsorbent consist of BET surface area, functional groups, and elemental analysis is presented. The data for attenuating the pollutants from a real wastewater treatment which was provided from a glass factory is also represented. More than 90% of fluoride content of the real wastewater was treated by the adsorbent. Generally, these data would be informative for extend research aim to industrial wastewater treatment and those who work in the wastewater treatment plants.

Silica/graphene oxide nanocomposites: Potential adsorbents for solid phase extraction of trace aflatoxins in cereal crops coupled with high performance liquid chromatography.

PubMed

Yu, Li; Ma, Fei; Ding, Xiaoxia; Wang, Hengling; Li, Peiwu

2018-04-15

Graphene oxide wrapped silica nanocomposites were synthesized and selected as solid phase extraction adsorbents for high performance liquid chromatography analysis of aflatoxins. The major parameters affecting extraction efficiency were optimized, including the amount of adsorbents, extraction time and desorption conditions. The limit of detections and the limit of quantifications were from 0.1 to 0.3 µg/kg and from 0.3 to 1.0 µg/kg, respectively. The recoveries of aflatoxins in the spiked maize and rice samples were in the range of 76.8-104.7% and 81.1-106.9%, respectively, and with the RSDs less than 12.4%. The proposed method was proven to be simple, rapid and reliable for routine analysis of aflatoxins in crops. Copyright © 2017 Elsevier Ltd. All rights reserved.

Extracting uranium from seawater: Promising AI series adsorbents

DOE PAGES

Das, Sadananda; Oyola, Y.; Mayes, Richard T.; ...

2015-11-10

A series of adsorbent (AI10 through AI17) were successfully developed at ORNL by radiation induced graft polymerization (RIGP) of acrylonitrile (AN) and vinylphosphonic acid (VPA) (at different mole/mole ratios) onto high surface area polyethylene fiber, with higher degree of grafting which ranges from 110 300%. The grafted nitrile groups were converted to amidoxime groups by reaction with 10 wt% hydroxylamine at 80 C for 72 hours. The amidoximated adsorbents were then conditioned with 0.44M KOH at 80 C followed by screening at ORNL with simulated seawater spiked with 8 ppm uranium. Uranium adsorption capacity in simulated seawater screening ranged frommore » 171-187 g-U/kg-ads irrespective of %DOG. The performance of the adsorbents for uranium adsorption in natural seawater was also carried out using flow-through-column at Pacific Northwest National Laboratory (PNNL). The three hours KOH conditioning was better for higher uranium uptake than one hour. The adsorbent AI11 containing AN and VPA at the mole ration of 3.52, emerged as the potential candidate for higher uranium adsorption (3.35 g-U/Kg-ads.) after 56 days of exposure in the seawater in the flow-through-column. The rate vanadium adsorption over uranium was linearly increased throughout the 56 days exposure. The total vanadium uptake was ~5 times over uranium after 56 days.« less

Extracting uranium from seawater: Promising AI series adsorbents

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

Das, Sadananda; Oyola, Y.; Mayes, Richard T.

A series of adsorbent (AI10 through AI17) were successfully developed at ORNL by radiation induced graft polymerization (RIGP) of acrylonitrile (AN) and vinylphosphonic acid (VPA) (at different mole/mole ratios) onto high surface area polyethylene fiber, with higher degree of grafting which ranges from 110 300%. The grafted nitrile groups were converted to amidoxime groups by reaction with 10 wt% hydroxylamine at 80 C for 72 hours. The amidoximated adsorbents were then conditioned with 0.44M KOH at 80 C followed by screening at ORNL with simulated seawater spiked with 8 ppm uranium. Uranium adsorption capacity in simulated seawater screening ranged frommore » 171-187 g-U/kg-ads irrespective of %DOG. The performance of the adsorbents for uranium adsorption in natural seawater was also carried out using flow-through-column at Pacific Northwest National Laboratory (PNNL). The three hours KOH conditioning was better for higher uranium uptake than one hour. The adsorbent AI11 containing AN and VPA at the mole ration of 3.52, emerged as the potential candidate for higher uranium adsorption (3.35 g-U/Kg-ads.) after 56 days of exposure in the seawater in the flow-through-column. The rate vanadium adsorption over uranium was linearly increased throughout the 56 days exposure. The total vanadium uptake was ~5 times over uranium after 56 days.« less

The Wide Field/Planetary Camera 2 (WFPC-2) molecular adsorber

NASA Technical Reports Server (NTRS)

Barengoltz, Jack; Moore, Sonya; Soules, David; Voecks, Gerald

1995-01-01

A device has been developed at the Jet Propulsion Laboratory, California Institute of Technology, for the adsorption of contaminants inside a space instrument during flight. The molecular adsorber was developed for use on the Wide Field Planetary Camera 2, and it has been shown to perform at its design specifications in the WFPC-2. The basic principle of the molecular adsorber is a zeolite-coated ceramic honeycomb. The arrangement is efficient for adsorption and also provides the needed rigidity to retain the special zeolite coating during the launch vibrational environment. The adsorber, on other forms, is expected to be useful for all flight instruments sensitive to internal sources of contamination. Typically, some internal contamination is unavoidable. A common design solution is to increase the venting to the exterior. However, for truly sensitive instruments, the external contamination environment is more severe. The molecular adsorber acts as a one-way vent to solve this problem. Continued development is planned for this device.

Powder-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

DOEpatents

Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

2016-05-03

A powder-based adsorbent and a related method of manufacture are provided. The powder-based adsorbent includes polymer powder with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the powder-based adsorbent includes irradiating polymer powder, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Powder-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

Foam-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

DOEpatents

Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

2015-06-02

Foam-based adsorbents and a related method of manufacture are provided. The foam-based adsorbents include polymer foam with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the foam-based adsorbents includes irradiating polymer foam, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Foam-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

Spinel type CoFe oxide porous nanosheets as magnetic adsorbents with fast removal ability and facile separation.

PubMed

Ge, X; Gu, C D; Wang, X L; Tu, J P

2015-09-15

Adsorption is often time consuming due to slow diffusion kinetic. Sizing he adsorbent down might help to accelerate adsorption. For CoFe spinel oxide, a magnetically separable adsorbent, the preparation of nanosheets faces many challenges including phase separation, grain growth and difficulty in preparing two-dimensional materials. In this work, we prepared porous CoFe oxide nanosheet with chemical formula of Co2.698Fe0.302O4 through topochemical transformation of a CoFe precursor, which has a layered double hydroxide (LDH) analogue structure and a large interlayer spacing. The LDH precursor was synthesized from a cheap deep eutectic solvent (DES) system. The calcined Co2.698Fe0.302O4 has small grain size (10-20nm), nanosheet morphology, and porous structure, which contribute to a large specific surface area of 79.5m(2)g(-1). The Co2.698Fe0.302O4 nanosheets show fast removal ability and good adsorption capacity for both organic waste (305mgg(-1) in 5min for Congo red) and toxic heavy metal ion (5.27mgg(-1) in 30min for Cr (VI)). Furthermore, the Co2.698Fe0.302O4 can be separated magnetically. Considering the precursor can be prepared through a fast, simple, surfactant-free and high-yield synthetic strategy, this work should have practical significance in fabricating adsorbents. Copyright © 2015 Elsevier Inc. All rights reserved.

[Selective removal of tannins from Polygonum cuspidatum extracts using collagen fiber adsorbent].

PubMed

Li, Juan; Liao, Xuepin; Shu, Xingxu; Shi, Bi

2010-03-01

To investigate the selective removal of tannins from Polygonum cuspidatum extracts by using collagen fiber adsorbent, and to evaluate the adsorption and desorption performances of collagen fiber adsorbent to tannins. The adsorbent was prepared from bovine skin collagen fiber through crosslinking reaction of glutaraldehyde, and then used for the selective removal of tannins from P. cuspidatum extracts. Gelatin-turbidity method, gelatin-ultraviolet spectrometry method and HPLC were used for detection of tannins in the solutions. Ethanol-water solutions with varying concentration were used to test their desorption ability of tannins in order to choose proper desorption solution. On the basis of batch experimental results, the column adsorption and desorption tests were carried out, by using gelatin-turbidity method for detection of tannins. The collagen fiber adsorbent exhibited excellent adsorption selectivity to tannins. It was found that tannins of P. cuspidatum were completely removed, while nearly no adsorption of active components (resveratrol as representative) was found. Moreover, the collagen fiber adsorbent could be regenerated by using 30% ethanol-water solution and then reused. The collagen fiber adsorbent can be considered as a promising material for selective removal of tannins from P. cuspidatum extracts.

Effect of adsorbent addition on floc formation and clarification.

PubMed

Younker, Jessica M; Walsh, Margaret E

2016-07-01

Adding adsorbent into the coagulation process is an emerging treatment solution for targeting hard-to-remove dissolved organic compounds from both drinking water and industrial wastewater. The impact of adding powdered activated carbon (PAC) or organoclay (OC) adsorbents with ferric chloride (FeCl3) coagulant was investigated in terms of potential changes to the coagulated flocs formed with respect to size, structure, and breakage and regrowth properties. The ability of dissolved air flotation (DAF) and sedimentation (SED) clarification processes to remove hybrid adsorbent-coagulant flocs was also evaluated through clarified water quality analysis of samples collected in bench-scale jar test experiments. The jar tests were conducted using both a synthetic fresh water and oily wastewater test water spiked with dissolved aromatic compounds phenol and naphthalene. Results of the study demonstrated that addition of adsorbent reduced the median coagulated floc size by up to 50% but did not affect floc strength or regrowth potential after application of high shear. Experimental results in fresh water demonstrated that sedimentation was more effective than DAF for clarification of both FeCl3-PAC and FeCl3-OC floc aggregates. However, experimental tests performed on the synthetic oily wastewater showed that coagulant-adsorbent floc aggregates were effectively removed with both DAF and sedimentation treatment, with lower residual turbidity achieved in clarified water samples than with coagulation treatment alone. Addition of OC or PAC into the coagulation process resulted in removals of over half, or nearly all of the dissolved aromatics, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Green Adsorbents for Wastewaters: A Critical Review

PubMed Central

Kyzas, George Z.; Kostoglou, Margaritis

2014-01-01

One of the most serious environmental problems is the existence of hazardous and toxic pollutants in industrial wastewaters. The major hindrance is the simultaneous existence of many/different types of pollutants as (i) dyes; (ii) heavy metals; (iii) phenols; (iv) pesticides and (v) pharmaceuticals. Adsorption is considered to be one of the most promising techniques for wastewater treatment over the last decades. The economic crisis of the 2000s led researchers to turn their interest in adsorbent materials with lower cost. In this review article, a new term will be introduced, which is called “green adsorption”. Under this term, it is meant the low-cost materials originated from: (i) agricultural sources and by-products (fruits, vegetables, foods); (ii) agricultural residues and wastes; (iii) low-cost sources from which most complex adsorbents will be produced (i.e., activated carbons after pyrolysis of agricultural sources). These “green adsorbents” are expected to be inferior (regarding their adsorption capacity) to the super-adsorbents of previous literature (complex materials as modified chitosans, activated carbons, structurally-complex inorganic composite materials etc.), but their cost-potential makes them competitive. This review is a critical approach to green adsorption, discussing many different (maybe in some occasions doubtful) topics such as: (i) adsorption capacity; (ii) kinetic modeling (given the ultimate target to scale up the batch experimental data to fixed-bed column calculations for designing/optimizing commercial processes) and (iii) critical techno-economical data of green adsorption processes in order to scale-up experiments (from lab to industry) with economic analysis and perspectives of the use of green adsorbents. PMID:28788460

Sum frequency generation and solid-state NMR study of the structure, orientation, and dynamics of polystyrene-adsorbed peptides

PubMed Central

Weidner, Tobias; Breen, Nicholas F.; Li, Kun; Drobny, Gary P.; Castner, David G.

2010-01-01

The power of combining sum frequency generation (SFG) vibrational spectroscopy and solid-state nuclear magnetic resonance (ssNMR) spectroscopy to quantify, with site specificity and atomic resolution, the orientation and dynamics of side chains in synthetic model peptides adsorbed onto polystyrene (PS) surfaces is demonstrated in this study. Although isotopic labeling has long been used in ssNMR studies to site-specifically probe the structure and dynamics of biomolecules, the potential of SFG to probe side chain orientation in isotopically labeled surface-adsorbed peptides and proteins remains largely unexplored. The 14 amino acid leucine-lysine peptide studied in this work is known to form an α-helical secondary structure at liquid-solid interfaces. Selective, individual deuteration of the isopropyl group in each leucine residue was used to probe the orientation and dynamics of each individual leucine side chain of LKα14 adsorbed onto PS. The selective isotopic labeling methods allowed SFG analysis to determine the orientations of individual side chains in adsorbed peptides. Side chain dynamics were obtained by fitting the deuterium ssNMR line shape to specific motional models. Through the combined use of SFG and ssNMR, the dynamic trends observed for individual side chains by ssNMR have been correlated with side chain orientation relative to the PS surface as determined by SFG. This combination provides a more complete and quantitative picture of the structure, orientation, and dynamics of these surface-adsorbed peptides than could be obtained if either technique were used separately. PMID:20628016

Oil palm biomass-based adsorbents for the removal of water pollutants--a review.

PubMed

Ahmad, Tanweer; Rafatullah, Mohd; Ghazali, Arniza; Sulaiman, Othman; Hashim, Rokiah

2011-07-01

This article presents a review on the role of oil palm biomass (trunks, fronds, leaves, empty fruit bunches, shells, etc.) as adsorbents in the removal of water pollutants such as acid and basic dyes, heavy metals, phenolic compounds, various gaseous pollutants, and so on. Numerous studies on adsorption properties of various low-cost adsorbents, such as agricultural wastes and its based activated carbons, have been reported in recent years. Studies have shown that oil palm-based adsorbent, among the low-cost adsorbents mentioned, is the most promising adsorbent for removing water pollutants. Further, these bioadsorbents can be chemically modified for better efficiency and can undergo multiple reuses to enhance their applicability at an industrial scale. It is evident from a literature survey of more than 100 recent papers that low-cost adsorbents have demonstrated outstanding removal capabilities for various pollutants. The conclusion is been drawn from the reviewed literature, and suggestions for future research are proposed.

Comparison of cadmium hydroxide nanowires and silver nanoparticles loaded on activated carbon as new adsorbents for efficient removal of Sunset yellow: Kinetics and equilibrium study.

PubMed

Ghaedi, Mehrorang

2012-08-01

Adsorption of Sunset yellow (SY) onto cadmium hydroxide nanowires loaded on activated carbon (Cd(OH)(2)-NW-AC) and silver nanoparticles loaded on activated carbon (Ag-NP-AC) was investigated. The effects of pH, contact time, amount of adsorbents, initial dye concentration, agitation speed and temperature on Sunset yellow removal on both adsorbents were studied. Following the optimization of variables, the experimental data were fitted to different conventional isotherm models like Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich (D-R) based on linear regression coefficient R(2) the Langmuir isotherm was found to be the best fitting isotherm model and the maximum monolayer adsorption capacities calculated based on this model for Cd(OH)(2)-NW-AC and Ag-NP-AC were found to be 76.9 and 37.03mg g(-1) at room temperatures, respectively. The experimental fitting of time dependency of adsorption of SY onto both adsorbent shows the applicability of second order kinetic model for interpretation of kinetic data. The pseudo-second order model best fits the adsorption kinetics. Thermodynamic parameters such as enthalpy, entropy, activation energy, sticking probability, and Gibb's free energy changes were also calculated. It was found that the sorption of SY over (Cd(OH)(2)-NW-AC) and (Ag-NP-AC) was spontaneous and endothermic in nature. Efficiency of the adsorbent was also investigated using real effluents and more than 95% SY removal for both adsorbents was observed. Copyright © 2012 Elsevier B.V. All rights reserved.

OZONE REACTION WITH N-ALDEHYDES (N=4-10), BENZALDEHYDE, ETHANOL, ISOPROPANOL, AND N-PROPANOL ADSORBED ON A DUAL-BED GRAPHITIZED CARBON/CARBON MOLECULAR SIEVE ADSORBENT CARTRIDGE

EPA Science Inventory

Ozone reacts with n-aldehydes (n = 4 - 10), benzaldehyde, ethanol, isopropanol, and n-propanol adsorbed on a dual-bed graphitized carbon/carbon molecular sieve adsorbent cartridge. Destruction of n-aldehydes increases with n number and with ozone concentration. In some samp...

Silver and zinc oxide nanostructures loaded on activated carbon as new adsorbents for removal of methylene green: a comparative study.

PubMed

Ghaedi, M; Karimi, H; Yousefi, F

2014-09-01

In this study, the removal of methylene green (MG) from aqueous solution based on two new adsorbents including silver nanoparticles and zinc oxide nanorods loaded on activated carbon (Ag-NP-AC and ZnO-NR-AC, respectively) has been carried out. The dependency of removal process to variables such as contact time, pH, amount of adsorbents, and initial MG concentration were examined and optimized. It was found that the maximum MG removal percentage was achieved at pH = 7.0 following stirring at 400 r min(-1) for 7 and 6 min for Ag-NP-AC and ZnO-NR-AC, respectively. Equilibrium data were well fitted with the Langmuir model having maximum adsorption capacity of 166.7 and 200 mg g(-1) for Ag-NP-AC and ZnO-NR-AC, respectively. Thermodynamic parameters of MG adsorption on Ag-NP-AC such as enthalpy and entropy changes, activation energy, sticking probability, and Gibbs free energy changes show the spontaneous and endothermic nature of the removal process. Among different conventional kinetic models, the pseudo second-order kinetics in addition to particle diffusion mechanism is the best and efficient model for the prediction and explanation of experimental data of MG adsorption onto both adsorbents. © The Author(s) 2014.

Evaluating of arsenic(V) removal from water by weak-base anion exchange adsorbents.

PubMed

Awual, M Rabiul; Hossain, M Amran; Shenashen, M A; Yaita, Tsuyoshi; Suzuki, Shinichi; Jyo, Akinori

2013-01-01

Arsenic contamination of groundwater has been called the largest mass poisoning calamity in human history and creates severe health problems. The effective adsorbents are imperative in response to the widespread removal of toxic arsenic exposure through drinking water. Evaluation of arsenic(V) removal from water by weak-base anion exchange adsorbents was studied in this paper, aiming at the determination of the effects of pH, competing anions, and feed flow rates to improvement on remediation. Two types of weak-base adsorbents were used to evaluate arsenic(V) removal efficiency both in batch and column approaches. Anion selectivity was determined by both adsorbents in batch method as equilibrium As(V) adsorption capacities. Column studies were performed in fixed-bed experiments using both adsorbent packed columns, and kinetic performance was dependent on the feed flow rate and competing anions. The weak-base adsorbents clarified that these are selective to arsenic(V) over competition of chloride, nitrate, and sulfate anions. The solution pH played an important role in arsenic(V) removal, and a higher pH can cause lower adsorption capacities. A low concentration level of arsenic(V) was also removed by these adsorbents even at a high flow rate of 250-350 h(-1). Adsorbed arsenic(V) was quantitatively eluted with 1 M HCl acid and regenerated into hydrochloride form simultaneously for the next adsorption operation after rinsing with water. The weak-base anion exchange adsorbents are to be an effective means to remove arsenic(V) from drinking water. The fast adsorption rate and the excellent adsorption capacity in the neutral pH range will render this removal technique attractive in practical use in chemical industry.

Extracting Uranium from Seawater: Promising AI Series Adsorbents

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

Das, S.; Oyola, Y.; Mayes, R. T.

A new series of adsorbents (AI10 through AI17) were successfully developed at ORNL by radiation induced graft polymerization (RIGP) of acrylonitrile (AN) and vinylphosphonic acid (VPA) (at different mole to mole ratios) onto high surface area polyethylene fiber, with high degrees of grafting (DOG) varying from 110 to 300%. The grafted nitrile groups were converted to amidoxime groups by reaction with 5 wt % hydroxylamine at 80 °C for 72 h. The amidoximated adsorbents were then conditioned with 0.44 M KOH at 80 °C followed by screening at ORNL with prescreening brine spiked with 8 ppm uranium. Uranium adsorption capacitiesmore » in prescreening ranged from 171 to 187 g-U/kg-ads irrespective of percent DOG. The performance of the adsorbents with respect to uranium adsorption in natural seawater was also investigated using flow-throughcolumn testing at the Pacific Northwest National Laboratory (PNNL). Three hours of KOH conditioning led to higher uranium uptake than 1 h of conditioning. The adsorbent AI11, containing AN and VPA at the mole ratio of 3.52, emerged as the potential candidate for the highest uranium adsorption (3.35 g-U/kg-ads.) after 56 days of exposure in seawater flow-through-columns. The rate of vanadium adsorption over uranium linearly increased throughout the 56 days of exposure. The total mass of vanadium uptake was ~5 times greater than uranium after 56 days.« less

Influence of hydrophobization of fumed oxides on interactions with polar and nonpolar adsorbates

NASA Astrophysics Data System (ADS)

Gun'ko, V. M.; Pakhlov, E. M.; Goncharuk, O. V.; Andriyko, L. S.; Marynin, A. I.; Ukrainets, A. I.; Charmas, B.; Skubiszewska-Zięba, J.; Blitz, J. P.

2017-11-01

A variety of unmodified and modified fumed silica A-300 and silica/titania (ST20 and ST76 at 20 and 76 wt.% of titania, respectively) was prepared to analyze features of their interactions with polar and nonpolar adsorbates. The materials were studied using nitrogen adsorption-desorption, ethanol evaporation kinetics, infrared (IR) spectroscopy, thermogravimetry (TG), photon correlation spectroscopy, differential scanning calorimetry (DSC), DSC and TG thermoporometry, and quantum chemistry. Changes in surface structure of modified nanooxides with increasing hydrophobization degree (ΘMS) from 20% to 100% have a strong affect on the textural characteristics of the materials and adsorption-desorption of various adsorbates. Confined space effects enhanced due to the location of adsorbates in narrow voids between nanoparticles lead to freezing-melting point depression for bound polar and nonpolar adsorbates. The behavior of particles of modified nanooxides in aqueous and water/ethanol media is strongly altered due to enhanced aggregations with increasing value of ΘMS. All of these change are non-monotonic functions of ΘMS which affects (i) rearrangement of nanoparticles, (ii) interactions with polar and nonpolar adsorbates, (iii) location of adsorbates in voids of different sizes, (iv) the clustering of adsorbates and formation of nearly bulk structures.

Investigations into the Reusability of Amidoxime-Based Polymeric Adsorbents for Seawater Uranium Extraction

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

Kuo, Li-Jung; Pan, Horng-Bin; Wai, Chien M.

The ability to re-use amidoxime-based polymeric adsorbents is a critical component in reducing the overall cost of the technology to extract uranium from seawater. This report describes an evaluation of adsorbent reusability in multiple re-use (adsorption/stripping) cycles in real seawater exposures with potassium bicarbonate (KHCO3) elution using several amidoxime-based polymeric adsorbents. The KHCO3 elution technique achieved ~100% recovery of uranium adsorption capacity in the first re-use. Subsequent re-uses showed significant drops in adsorption capacity. After the 4th re-use with the ORNL AI8 adsorbent, the 56-day adsorption capacity dropped to 28% of its original capacity. FTIR spectra revealed that there wasmore » a conversion of the amidoxime ligands to carboxylate groups during extended seawater exposure, becoming more significant with longer the exposure time. Ca and Mg adsorption capacities also increased with each re-use cycle supporting the hypothesis that long term exposure resulted in converting amidoxime to carboxylate, enhancing the adsorption of Ca and Mg. Shorter seawater exposure (adsorption/stripping) cycles (28 vs. 42 days) had higher adsorption capacities after re-use, but the shorter exposure cycle time did not produce an overall better performance in terms of cumulative exposure time. Recovery of uranium capacity in re-uses may also vary across different adsorbent formulations. Through multiple re-use the adsorbent AI8 can harvest 10 g uranium/kg adsorbent in ~140 days, using a 28-day adsorption/stripping cycle, a performance much better than would be achieved with a single use of the adsorbent through very long-term exposure (saturation capacity = 7.4 g U/kg adsorbent). A time dependent seawater exposure model to evaluate the cost associated with reusing amidoxime-based adsorbents in real seawater exposures was developed. The cost to extract uranium from seawater ranged from $610-830/kg U was predicted. Model simulation suggests that a

The use of date palm as a potential adsorbent for wastewater treatment: a review.

PubMed

Ahmad, Tanweer; Danish, Mohammad; Rafatullah, Mohammad; Ghazali, Arniza; Sulaiman, Othman; Hashim, Rokiah; Ibrahim, Mohamad Nasir Mohamad

2012-06-01

In tropical countries, the palm tree is one of the most abundant and important trees. Date palm is a principal fruit grown in many regions of the world. It is abundant, locally available and effective material that could be used as an adsorbent for the removal of different pollutants from aqueous solution. This article presents a review on the role of date palm as adsorbents in the removal of unwanted materials such as acid and basic dyes, heavy metals, and phenolic compounds. Many studies on adsorption properties of various low cost adsorbent, such as agricultural waste and activated carbons based on agricultural waste have been reported in recent years. Studies have shown that date palm-based adsorbents are the most promising adsorbents for removing unwanted materials. No previous review is available where researchers can get an overview of the adsorption capacities of date palm-based adsorbent used for the adsorption of different pollutants. This review provides the recent literature demonstrating the usefulness of date palm biomass-based adsorbents in the adsorption of various pollutants.

SERS spectra of pyridine adsorbed on nickel film prepared by magnetron sputtering

NASA Astrophysics Data System (ADS)

Li, Daoyong; Ouyang, Yu; Chen, Li; Cao, Weiran; Shi, Shaohua

2011-02-01

As a repeating well and cheaper enhancement substrate, the nickel film was fabricated with magnetron sputtering coating instrument. Surface enhanced Raman spectra (SERS) of pyridine adsorbed on this nickel film are compared with the experimental values of gaseous pyridine, the theoretical value of pyridine solution listed in other literatures and our method is better than electro-chemical etching electrode method for large scale preparation. The enhancement factor of the nickel film is calculated and the result indicates that magnetron sputtering coating technology is feasible for obtaining good SERS active surface.

Comparative study of selenite adsorption on carbon based adsorbents and activated alumina.

PubMed

Jegadeesan, G; Mondal, K; Lalvani, S B

2003-08-01

The sorption characteristics of carbon-based adsorbents such as activated carbon and chitin for the removal of selenite, Se (IV), an anionic, hazardous contaminant, are compared with those of alpha and gamma alumina. Batch experiments were conducted to determine the influence of pH, concentration of adsorbate, adsorbent loading and temperature on the sorption characteristics of the adsorbents. Generally, low pH of the solution resulted in favorable selenium removal. With the exception of activated carbon, uptakes decreased with increase in temperature. In comparison, chitin was found to be far less effective for the removal of Se (IV) from aqueous solutions. The data also showed that gamma alumina provided higher selenium removal percentages (99%) compared to alpha alumina (94%), activated carbon (87%) and chitin (49%). The selenite removal was found to decrease with increasing initial Se (IV) concentration in the solution. Adsorption capacities of the adsorbents are reported in terms of their Langmuir adsorption isotherms. The adsorption capacity (on unit mass basis) of the adsorbents for selenite is in the order: chitin (specific area (sa) = 9.58 m2 g(-1)) < activated carbon (sa = 96.37 m2 g(-1)) < alpha alumina (sa = 6 m2 g(-1)) < gamma alumina (sa = 150 m2 g(-1)).

REGENERATION AND REACTIVATION OF CARBON ADSORBENTS BY RADIO FREQUENCY INDUCTION HEATING

EPA Science Inventory

1. Electrical Properties of Adsorbents: We measured the electric permittivity of four commercially available carbon adsorbents (supplied by Wesvaco Inc) over the radio frequency range (1 to 40 MHz). Westvaco is by far the largest volume supplier of activated carbon...

Smart Adsorbents with Photoregulated Molecular Gates for Both Selective Adsorption and Efficient Regeneration.

PubMed

Cheng, Lei; Jiang, Yao; Yan, Ni; Shan, Shu-Feng; Liu, Xiao-Qin; Sun, Lin-Bing

2016-09-07

Selective adsorption and efficient regeneration are two crucial issues for adsorption processes; unfortunately, only one of them instead of both is favored by traditional adsorbents with fixed pore orifices. Herein, we fabricated a new generation of smart adsorbents through grafting photoresponsive molecules, namely, 4-(3-triethoxysilylpropyl-ureido)azobenzene (AB-TPI), onto pore orifices of the support mesoporous silica. The azobenzene (AB) derivatives serve as the molecular gates of mesopores and are reversibly opened and closed upon light irradiation. Irradiation with visible light (450 nm) causes AB molecules to isomerize from cis to trans configuration, and the molecular gates are closed. It is easy for smaller adsorbates to enter while difficult for the larger ones, and the selective adsorption is consequently facilitated. Upon irradiation with UV light (365 nm), the AB molecules are transformed from trans to cis isomers, promoting the desorption of adsorbates due to the opened molecular gates. The present smart adsorbents can consequently benefit not only selective adsorption but also efficient desorption, which are exceedingly desirable for adsorptive separation but impossible for traditional adsorbents with fixed pore orifices.

Method of recovering adsorbed liquid compounds from molecular sieve columns

DOEpatents

Burkholder, H.R.; Fanslow, G.E.

1983-12-20

Molecularly adsorbed volatile liquid compounds are recovered from molecular sieve adsorbent columns by directionally applying microwave energy to the bed of the adsorbent to produce a mixed liquid-gas effluent. The gas portion of the effluent generates pressure within the bed to promote the discharge of the effluent from the column bottoms. Preferably the discharged liquid-gas effluent is collected in two to three separate fractions, the second or intermediate fraction having a substantially higher concentration of the desorbed compound than the first or third fractions. The desorption does not need to be assisted by passing a carrier gas through the bed or by applying reduced pressure to the outlet from the bed. 8 figs.

Method of recovering adsorbed liquid compounds from molecular sieve columns

DOEpatents

Burkholder, Harvey R.; Fanslow, Glenn E.

1983-01-01

Molecularly adsorbed volatile liquid compounds are recovered from molecular sieve adsorbent columns by directionally applying microwave energy to the bed of the adsorbent to produce a mixed liquid-gas effluent. The gas portion of the effluent generates pressure within the bed to promote the discharge of the effluent from the column bottoms. Preferably the discharged liquid-gas effluent is collected in two to three separate fractions, the second or intermediate fraction having a substantially higher concentration of the desorbed compound than the first or third fractions. The desorption does not need to be assisted by passing a carrier gas through the bed or by applying reduced pressure to the outlet from the bed.

An eco-friendly approach for heavy metal adsorbent regeneration using CO2-responsive molecular octopus.

PubMed

Bai, Yu; Liang, Yen Nan; Hu, Xiao

2017-10-01

Perennial problems of adsorption in wastewater treatment include adsorbent recycling, generation of waste sludge and secondary pollution because harmful concentrated acids, bases or strong chelators are often used for adsorbent regeneration and adsorbate recovery. We report, for the first time, an eco-friendly regeneration concept demonstrated with a CO 2 -responsive octopus-like polymeric adsorbent. Various heavy metals can be scavenged at very high Q e by such adsorbent through coordination. Most importantly, the rapid and complete regeneration of the adsorbent and recovery of the heavy metal ions can be readily achieved by CO 2 bubbling within a few minutes under mild conditions, i.e., room temperature and atmospheric pressure. The adsorbent can then be restored to its adsorptive state and reused upon removal of CO 2 by simply bubbling another gas. This eco-friendly, effective, ultra-fast and repeatable CO 2 -triggered regeneration process using CO 2 -responsive adsorbent with versatile structure, morphology or form can be incorporated into a sustainable closed-loop wastewater treatment process to solve the perennial problems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stabilization of arsenic and fluoride bearing spent adsorbent in clay bricks: Preparation, characterization and leaching studies.

PubMed

Rathore, Vineet Kumar; Mondal, Prasenjit

2017-09-15

The presence of arsenic and fluoride in groundwater has been observed throughout the world. Many technologies have been developed by various research groups in order to tackle this problem. Adsorption has emerged as one of the best possible technique for the removal of arsenic, fluoride and many other pollutants from drinking water. Although a considerable amount of work has been published on the adsorptive removal of arsenic and fluoride, the area related to the management of spent adsorbent is not well explored. Present paper deals with the adsorptive removal of arsenic and fluoride from aqueous solution by three different types of adsorbents, namely, thermally treated laterite (TTL), acid-base treated laterite (ABTL) and aluminum oxide/hydroxide nanoparticles (AHNP). Under the experimental conditions in batch operation, the adsorption capacities of TTL, ABLT and AHNP for arsenic are found to be 6.43 μg/g, 9.25 μg/g and 48.5 μg/g respectively, whereas for fluoride, these values are found as 0.21 mg/g, 0.85 mg/g and 4.65 mg/g respectively. After adsorption, the spent adsorbents have been stabilized in the form of clay bricks. The effects of spent adsorbent concentration on the properties of bricks and their leaching properties are investigated. The bricks have been tested for various properties like density, percentage water absorption, shrinkage, compressive strength and efflorescence. The maximum values of density and shrinkage of the bricks formed are found as 2.3 g/cm 3 and 10.2%, whereas the percentage water absorption and compressive strength of the bricks are found between 11 and 14% and 35 to 150 kgf/cm 2 respectively. All the test results are in accordance with the criteria set by Indian Standards. The leaching test of arsenic and fluoride from the bricks reveals that their maximum values in leachate are 510 μg/L and 2.1 mg/L respectively, which are below the permissible limits of USEPA standards. Copyright © 2017 Elsevier Ltd. All rights

Geosciences help to protect human health: estimation of the adsorbed radiation doses while flight journeys, as important step to radiation risk assessment

NASA Astrophysics Data System (ADS)

Chernov, Anatolii; Shabatura, Olexandr

2016-04-01

Estimation of the adsorbed radiation dose while flight journeys is a complex problem, which should be solved to get correct evaluation of equivalent effective doses and radiation risk assessment. Direct measurements of the adsorbed dose in the aircrafts during regional flights (3-10 hours) has shown that the radiation in the plane may increase 10-15 times (to 2-4 mSv/h) compared to the values on the surface of the Earth (0.2-0.5 mSv/h). Results of instrumental research confirmed by the other investigations. It is a fact that adsorbed doses per year while flight journeys are less than doses from medical tests. However, while flight journeys passengers get the same doses as nuclear power plant staff, people in zones of natural radiation anomalies and so should be evaluated. According to the authors' research, flight journeys are safe enough, when solar activity is normal and if we fly under altitude of 18 km (as usual, while intercontinental flights). Most of people travel by plane not so often, but if flight is lasting in dangerous periods of solar activity (powerful solar winds and magnetic field storms), passengers and flight crew can adsorb great amount of radiation doses. People, who spend more than 500 hours in flight journeys (pilots, business oriented persons', government representatives, etc.) get amount of radiation, which can negatively influence on health and provoke diseases, such as cancer. Authors consider that problem actual and researches are still going on. It is revealed, that radiation can be calculated, using special equations. Great part of radiation depends on very variable outer-space component and less variable solar. Accurate calculations of doses will be possible, when we will take into account all features of radiation distribution (time, season of year and exact time of the day, duration of flight), technical features of aircraft and logistics of flight (altitude, latitude). Results of first attempts of radiation doses modelling confirmed

Preparation and characterization of novel carbon dioxide adsorbents based on polyethylenimine-modified Halloysite nanotubes.

PubMed

Cai, Haohao; Bao, Feng; Gao, Jie; Chen, Tao; Wang, Si; Ma, Rui

2015-01-01

New nano-sized carbon dioxide (CO2) adsorbents based on Halloysite nanotubes impregnated with polyethylenimine (PEI) were designed and synthesized, which were excellent adsorbents for the capture of CO2 at room temperature and had relatively high CO2 adsorption capacity. The prepared adsorbents were characterized by various techniques such as Fourier transform infrared spectrometry, gel permeation chromatography, dynamic light scattering, thermogravimetry, thermogravimetry-Fourier transform-infrared spectrometry, scanning electron microscopy and transmission electron microscopy. The adsorption characteristics and capacity were studied at room temperature, the highest CO2 adsorption capacity of 156.6 mg/g-PEI was obtained and the optimal adsorption capacity can reach a maximum value of 54.8 mg/g-adsorbent. The experiment indicated that this kind of adsorbent has a high stability at 80°C and PEI-impregnated adsorbents showed good reversibility and stability during cyclic adsorption-regeneration tests.

Physicochemical controls on adsorbed water film thickness in unsaturated geological media

NASA Astrophysics Data System (ADS)

Tokunaga, Tetsu K.

2011-08-01

Adsorbed water films commonly coat mineral surfaces in unsaturated soils and rocks, reducing flow and transport rates. Therefore, it is important to understand how adsorbed film thickness depends on matric potential, surface chemistry, and solution chemistry. Here the problem of adsorbed water film thickness is examined by combining capillary scaling with the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Novel aspects of this analysis include determining capillary influences on film thicknesses and incorporating solution chemistry-dependent electrostatic potential at air-water interfaces. Capillary analysis of monodisperse packings of spherical grains provided estimated ranges of matric potentials where adsorbed films are stable and showed that pendular rings within drained porous media retain most of the "residual" water except under very low matric potentials. Within drained pores, capillary contributions to thinning of adsorbed films on spherical grains are shown to be small, such that DLVO calculations for flat surfaces are suitable approximations. Hamaker constants of common soil minerals were obtained to determine ranges of the dispersion component to matric potential-dependent film thickness. The pressure component associated with electrical double-layer forces was estimated using the compression and linear superposition approximations. The pH-dependent electrical double-layer pressure component is the dominant contribution to film thicknesses at intermediate values of matric potential, especially in lower ionic strength solutions (<10 mol m-3) on surfaces with higher-magnitude electrostatic potentials (more negative than ≈-50 mV). Adsorbed water films are predicted to usually range in thickness from ≈1 to 20 nm in drained pores and fractures of unsaturated environments.

Electronic and magnetic properties of nonmetal atoms adsorbed ReS{sub 2} monolayers

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

Zhang, Xiaoou; Li, Qingfang, E-mail: qingfangli@nuist.edu.cn; Department of Physics, Nanjing University of Information Science and Technology, Nanjing 210044

2015-08-14

The stable configurations and electronic and magnetic properties of nonmetal atoms (H, N, P, O, S, F, and Cl) adsorbed ReS{sub 2} monolayers have been investigated by first-principles calculations. It is found that H, O, S, F, and Cl prefer to occupy the peak sites of S atoms, while both N and P atoms favor the valley sites of S atoms. The ReS{sub 2} sheet exhibits a good adsorption capability to nonmetal atoms. The reconstruction of the surface is pronounced in N- and P-adsorbed ReS{sub 2} monolayers. In H-adsorbed case, the Fermi level is pulled into the conduction band, whichmore » results in the semiconductor-metal transition. The same magnetic moment of 1μ{sub B} is found in the N-, P-, F-, and Cl-adsorbed ReS{sub 2} monolayers, while the mechanisms of forming magnetic moment for N (P)- and F (Cl)-adsorbed cases are different. In addition, the spatial extensions of spin density in P-, F-, and Cl-adsorbed cases are larger than that in N-adsorbed case, which is more suitable to achieve long-range magnetic coupling interaction at low defect concentrations. Our results provide insight for achieving metal-free magnetism and a tunable band gap for various electronic and spintronic devices based on ReS{sub 2}.« less

Suppression of single-wall carbon nanotube redox reaction by adsorbed proteins

NASA Astrophysics Data System (ADS)

Nakayama, Tomohito; Tanaka, Takeshi; Shiraki, Kentaro; Hase, Muneaki; Hirano, Atsushi

2018-07-01

Single-wall carbon nanotubes (SWCNTs) are widely used in biological applications. In biological systems, proteins readily adsorb to SWCNTs. However, little is known about the effects of proteins on the physicochemical properties of SWCNTs, such as their redox reaction. In this study, we measured the absorption and Raman spectra of SWCNTs dispersed in the presence of proteins such as bovine serum albumin to observe the redox reaction of the protein-adsorbed SWCNTs. The adsorbed proteins suppressed the redox reaction by forming thick and dense layers around the SWCNTs. Our findings are useful for understanding the behaviors of SWCNTs in biological systems.

Activated Carbon-hydrogen based Continuous Sorption Cooling in Single Adsorbent Bed with LN2 Heat Sink

NASA Astrophysics Data System (ADS)

Koley, Susmita; Ghosh, Indranil

Quick and periodic inflow-outflow of adsorbate in an adsorbent column createsa differential temperature between the two ends of it, allowing for the generation of continuous sorption cooling in a single adsorbent tube. The concept has been proven experimentally and theoretically for near room temperature applications using activated carbon-nitrogen. The feasibility of generating continuous solid sorption cooling in a single adsorbent tube in the cryogenic domainhas been studied theoretically with a different adsorbent-adsorbate pair, namely, activated carbon-hydrogen. Precooling of gaseous hydrogen (before it enters the adsorbent column) and removal of the heat of adsorption has been achieved using liquid nitrogen. Theoretical estimation shows nearly 20 K temperature difference between the two ends under no load condition. Finally, parametric variations have been performed.

The synthesis of corncobs (zea mays) active charcoal and water hyacinth (eichornia crassipes) adsorbent to adsorb Pb(II) with it’s analysis using solid-phase spectrophotometry (sps)

NASA Astrophysics Data System (ADS)

Saputro, S.; Masykuri, M.; Mahardiani, L.; Kurniastuti, D.

2018-03-01

This research aim to examine the effect of the combination between corncobs and water hyacinth to adsorb lead (II), the most effective combination have determined by compared the ratio of corncobs adsorbent and water hyacinth to the increasing adsorption of the Pb(II), prove the effectiveness of the solid-phase spectrophotometry (sps) to determine the levels of Pb(II) as the result of the corncobs active charcoal adsorption and water hyacinth in the level of µg/L. The research method used is experimental method. The data collecting technique is carried out by several stages, which are carbonization using muffle furnace at a temperature of 350°C for 1.5 hours, activation of the corncobs charcoal and water hyacinth using HCl 1M and HCl 5M activator, contacting the adsorbent of corncobs active charcoal and water hyacinth with liquid waste simulation of Pb(II) using variation of corncobns and water hyacinth, 1:0; 0:1; 1:1; 2:1; 1:2, analysis of Pb(II) using an sps, characterization of corncobs active charcoal adsorbent and water hyacinth using FTIR. Research results show that the combined effect of activated charcoal corncobs and water hyacinth can increase the ability of the adsorbent to absorb Pb(II), the optimum adsorbent mass ratio of 1:1 with the absorption level of 90.33%, SPS is an effective method to analyze the decreasing level of Pb(II) as the adsorbtion result of the corncobs active charcoal and water hyacinth in the level of µg/L, with the limit of detection (LOD) of 0.06 µg/L.

The determination of optimum condition in water hyacinth drying process by mixed adsorption drying method and modified fly ash as an adsorbent

NASA Astrophysics Data System (ADS)

Saputra, Asep Handaya; Putri, Rizky Anggreini

2017-05-01

Water hyacinth is an aquatic weed that has a very fast growth which makes it becomes a problem to the ecosystem. On the other hand, water hyacinth has a high fiber content (up to 20% by weight) which makes it potential to become raw material for composites and textile industries. As an aquatic plant, water hyacinth has a high initial moisture content that reaches more than 90%. Meanwhile the moisture content of fiber as a raw material for composite and textile industry should not be more than 10% to maintain the good quality of the products. Mixed adsorption drying method is one of the innovative method that can replace conventional drying process. Fluidization method which has been commonly used in agricultural and pharmaceutical products drying, can be enhanced by combining it with the adsorption method as performed in this study. In mixed fluidization-adsorption drying method, fly ash as adsorbent and water hyacinth fiber were put together into the fluidization column where the drying air evaporate the moisture content in water hyacinth fiber. In addition, the adsorbent adsorb the moisture content in the drying air to make the moisture content of the drying air remain low. The drying process is performed in various temperature and composition of water hyacinth and adsorbent in order to obtain the optimum drying condition. In addition, the effect of fly ash pellet and fly ash powder to the drying process was also performed. The result shows that the higher temperature and the more amount of adsorbent results in the faster drying rate. Fly ash pellet shows a better adsorption since it has a smaller pore diameter and wider surface area. The optimum temperature obtained from this study is 60°C and the optimum ratio of water hyacinth and fly ash is 50:50.

Poultry manure as raw material for mercury adsorbents in gas applications

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

Klasson, K.T.; Lima, I.M.; Boihem, L.L.

2009-09-30

The quantity of poultry manure generated each year is large, and technologies that take advantage of the material should be explored. At the same time, increased emphasis on the reduction of mercury emissions from coal-fired electric power plants has resulted in environmental regulations that may, in the future, require application of activated carbons as mercury sorbents. The sorbents could be injected into the flue gas stream, where they could adsorb the mercury. The sorbents (now containing mercury) would be removed via filtration or other means from the flue gas. Our preliminary work has demonstrated that activated carbon made from poultrymore » manure can adsorb mercury from air with good efficiency. In laboratory experiments, an activated carbon made from turkey cake manure removed the majority of elemental mercury from a hot air stream. Other activated carbons made from chicken and turkey litter manure were also efficient. In general, unwashed activated carbons made from poultry manure were more efficient in removing mercury than their acid-washed counterparts. The results suggest that the adsorption of mercury was mainly due to chemisorption on the surface of the carbon. Other potential uses for the activated carbons are the removal of mercury from air and natural gas.« less

Adsorbate-driven morphological changes on Cu(111) nano-pits

DOE PAGES

Mudiyanselage, K.; Xu, F.; Hoffmann, F. M.; ...

2014-12-09

Adsorbate-driven morphological changes of pitted-Cu(111) surfaces have been investigated following the adsorption and desorption of CO and H. The morphology of the pitted-Cu(111) surfaces, prepared by Ar + sputtering, exposed a few atomic layers deep nested hexagonal pits of diameters from 8 to 38 nm with steep step bundles. The roughness of pitted-Cu(111) surfaces can be healed by heating to 450-500 K in vacuum. Adsorption of CO on the pitted-Cu(111) surface leads to two infrared peaks at 2089-2090 and 2101-2105 cm -1 for CO adsorbed on under-coordinated sites in addition to the peak at 2071 cm -1 for CO adsorbedmore » on atop sites of the close-packed Cu(111) surface. CO adsorbed on under-coordinated sites is thermally more stable than that of atop Cu(111) sites. Annealing of the CO-covered surface from 100 to 300 K leads to minor changes of the surface morphology. In contrast, annealing of a H covered surface to 300 K creates a smooth Cu(111) surface as deduced from infrared data of adsorbed CO and scanning tunnelling microscopy (STM) imaging. The observation of significant adsorbate-driven morphological changes with H is attributed to its stronger modification of the Cu(111) surface by the formation of a sub-surface hydride with a hexagonal structure, which relaxes into the healed Cu(111) surface upon hydrogen desorption. These morphological changes occur ~150 K below the temperature required for healing of the pitted-Cu(111) surface by annealing in vacuum. In contrast, the adsorption of CO, which only interacts with the top-most Cu layer and desorbs by 160 K, does not significantly change the morphology of the pitted-Cu(111) surface.« less

Photoemission into water adsorbed on metals: Probing dissociative electron transfer using theory

NASA Astrophysics Data System (ADS)

Zhang, Yu; Whitten, J. L.

The photoinduced dissociation of water adsorbed on a silver nanoparticle is explored using theory to probe reaction pathways that produce hydrogen. Ab initio configuration theory is used to describe the systems. A formulation that allows excited electronic states embedded in a near continuum of lower energy states to be calculated accurately is described. Electron attachment of a photoemitted electron to adsorbed water can lead to the formation of H2 at a very low energy barrier with oxygen remaining on the Ag surface. A large energy barrier to form H2 plus adsorbed O is found for the ground state. The excited state has a much smaller barrier to OH stretch; however, to dissociate, the system must cross over from the excited state to the ground state potential energy surface. The cross over point is near the transition state for a ground state process. A characteristic feature of the excited state potential curve is an increase in energy in the early stages of OH stretch as the charge transfer state evolves from a state with considerable Rydberg character to one that has a typical OH antibonding molecular orbital. Another pathway releases a H atom leaving OH on the surface. Effects due to doping of a Ag nanoparticle with a K electron donor atom are compared with those caused by a Fermi level shift due to an applied potential. Results are also reported for electron transfer to a solvated lithium ion, Li(H2O) 6+, near the surface of a silver particle. A steering mechanism is found that involves the interaction of a hydridic hydrogen formed after electron transfer with an acidic hydrogen of a second solvated water molecule.

Effect of large amounts of dihydroxyacetone in the diet of rats.

NASA Technical Reports Server (NTRS)

Shapira, J.

1972-01-01

Experiments in which dihydroxyacetone (DHA) was used as nutrient for growing rats have not fulfilled the expectation that DHA could be used as a significant portion of the diet. Any attempt to treat major cerebral damage by prolonged administration of DHA is strongly contraindicated. For this reason, regenerated formose mixtures containing appreciable amounts of DHA will not be suitable as a significant portion of the diet for the crews of long-duration space missions.

Physical adsorption at the nanoscale: Towards controllable scaling of the substrate-adsorbate van der Waals interaction

NASA Astrophysics Data System (ADS)

Ambrosetti, Alberto; Silvestrelli, Pier Luigi; Tkatchenko, Alexandre

2017-06-01

The Lifshitz-Zaremba-Kohn (LZK) theory is commonly considered as the correct large-distance limit for the van der Waals (vdW) interaction of adsorbates (atoms, molecules, or nanoparticles) with solid substrates. In the standard approximate form, implicitly based on local dielectric functions, the LZK approach predicts universal power laws for vdW interactions depending only on the dimensionality of the interacting objects. However, recent experimental findings are challenging the universality of this theoretical approach at finite distances of relevance for nanoscale assembly. Here, we present a combined analytical and numerical many-body study demonstrating that physical adsorption can be significantly enhanced at the nanoscale. Regardless of the band gap or the nature of the adsorbate specie, we find deviations from conventional LZK power laws that extend to separation distances of up to 10-20 nm. Comparison with recent experimental observations of ultra-long-ranged vdW interactions in the delamination of graphene from a silicon substrate reveals qualitative agreement with the present theory. The sensitivity of vdW interactions to the substrate response and to the adsorbate characteristic excitation frequency also suggests that adsorption strength can be effectively tuned in experiments, paving the way to an improved control of physical adsorption at the nanoscale.

The structural and electronic properties of metal atoms adsorbed on graphene

NASA Astrophysics Data System (ADS)

Liu, Wenjiang; Zhang, Cheng; Deng, Mingsen; Cai, Shaohong

2017-09-01

Based on density functional theory (DFT), we studied the structural and electronic properties of seven different metal atoms adsorbed on graphene (M + graphene). The geometries, adsorption energies, density of states (DOS), band structures, electronic dipole moment, magnetic moment and work function (WF) of M + graphene were calculated. The adsorption energies ΔE indicated that Li, Na, K, Ca and Fe adsorbed on graphene were tending to form stable structures. However, diffusion would occur on Cu and Ag adsorbed on graphene. In addition, the electronic structure near the Fermi level of graphene was significantly affected by Fe (Cu and Ag), compared with Li (Na, K and Ca). The electronic dipole moment and magnetic moment of M + graphene were sensitive to the adsorbed metal atoms. Moreover, we found electropositive (electronegative) adsorption can decrease (increase) the WF of the surface. Specially, the WF of Ag + graphene and Fe + graphene would increase because surface dipole moment make a contribution to electron.

Kinetic Assembly of Near-IR Active Gold Nanoclusters using Weakly Adsorbing Polymers to Control Size

PubMed Central

Tam, Jasmine M.; Murthy, Avinash K.; Ingram, Davis R.; Nguyen, Robin; Sokolov, Konstantin V.; Johnston, Keith P.

2013-01-01

Clusters of metal nanoparticles with an overall size less than 100 nm and high metal loadings for strong optical functionality, are of interest in various fields including microelectronics, sensors, optoelectronics and biomedical imaging and therapeutics. Herein we assemble ~5 nm gold particles into clusters with controlled size, as small as 30 nm and up to 100 nm, which contain only small amounts of polymeric stabilizers. The assembly is kinetically controlled with weakly adsorbing polymers, PLA(2K)-b-PEG(10K)-b-PLA(2K) or PEG (MW = 3350), by manipulating electrostatic, van der Waals (VDW), steric, and depletion forces. The cluster size and optical properties are tuned as a function of particle volume fractions and polymer/gold ratios to modulate the interparticle interactions. The close spacing between the constituent gold nanoparticles and high gold loadings (80–85% w/w gold) produce a strong absorbance cross section of ~9×10−15 m2 in the NIR at 700 nm. This morphology results from VDW and depletion attractive interactions that exclude the weakly adsorbed polymeric stabilizer from the cluster interior. The generality of this kinetic assembly platform is demonstrated for gold nanoparticles with a range of surface charges from highly negative to neutral, with the two different polymers. PMID:20361735

Gas storage using fullerene based adsorbents

NASA Technical Reports Server (NTRS)

Mikhael, Michael G. (Inventor); Loutfy, Raouf O. (Inventor); Lu, Xiao-Chun (Inventor); Li, Weijiong (Inventor)

2000-01-01

This invention is directed to the synthesis of high bulk density high gas absorption capacity adsorbents for gas storage applications. Specifically, this invention is concerned with novel gas absorbents with high gravimetric and volumetric gas adsorption capacities which are made from fullerene-based materials. By pressing fullerene powder into pellet form using a conventional press, then polymerizing it by subjecting the fullerene to high temperature and high inert gas pressure, the resulting fullerene-based materials have high bulk densities and high gas adsorption capacities. By pre-chemical modification or post-polymerization activation processes, the gas adsorption capacities of the fullerene-based adsorbents can be further enhanced. These materials are suitable for low pressure gas storage applications, such as oxygen storage for home oxygen therapy uses or on-board vehicle natural gas storage. They are also suitable for storing gases and vapors such as hydrogen, nitrogen, carbon dioxide, and water vapor.

Poorly crystalline hydroxyapatite: A novel adsorbent for enhanced fulvic acid removal from aqueous solution

NASA Astrophysics Data System (ADS)

Wei, Wei; Yang, Lei; Zhong, Wenhui; Cui, Jing; Wei, Zhenggui

2015-03-01

In this study, poorly crystalline hydroxyapatite (HAP) was developed as an efficient adsorbent for the removal of fulvic acid (FA) from aqueous solution. Surface functionality, crystallinity, and morphology of the synthetic adsorbent were studied by Fourier-transformation infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of various parameters such as crystallinity of adsorbent, contact time, adsorbent dosage, pH, initial adsorbate concentration, temperature, ionic strength and the presence of alkaline earth metal ions on FA adsorption were investigated. Results indicated that the nanosized HAP calcined at lower temperature was poorly crystalline (Xc = 0.23) and had better adsorption capacity for FA than those (Xc = 0.52, 0.86) calcined at higher temperature. FA removal was increased with increases of adsorbent dosage, temperature, ionic strength and the presence of alkali earth metal ions, but decreased as the pH increased. Kinetic studies showed that pseudo-second-order kinetic model better described the adsorption process. Equilibrium data were best described by Sips models, and the estimated maximum adsorption capacity of poorly crystalline HAP was 90.20 mg/g at 318 K, displaying higher efficiency for FA removal than previously reported adsorbents. FT-IR results revealed that FA adsorption over the adsorbent could be attributed to the surface complexation between the oxygen atom of functional groups of FA and calcium ions of HAP. Regeneration studies indicated that HAP could be recyclable for a long term. Findings of the present work highlight the potential for using poorly crystalline HAP nanoparticles as an effective and recyclable adsorbent for FA removal from aqueous solution.

Characteristics of Microactive Carbon from Bamboo Var. Petung as Adsorbent

NASA Astrophysics Data System (ADS)

Wirawan, I. P. S.; Sutrisno; Seminar, K. B.; Nelwan, L. O.

2018-05-01

Bamboo has unique characteristics, such as in the carbonization process at a temperature of 500°C, the carbon characteristics is homogeneous. The characteristics of bamboo have great potential as a future bio-energy resource. Apart from being a bio-energy source of bamboo can also be used as an adsorbent material in the form of activated carbon. Activated carbon is the most inexpensive and easy to produce adsorbent material. One of the activated carbons of bamboo materials used is the micro-active carbon from bamboo. Microactivated carbon bamboo has a pore structure which is good for adsorption because of its surface area being much better than the other adsorbent, mainly on mesopore and micropore pore size. The purpose of this research is to make micro-activated carbon adsorbent bamboo var. petungand to analyze their characteristics. The characteristic of microactivecarbon was analyzed by SEM EDS and Iod number. The result showed a variation in pore size from 1μm to 11.157μm. The surface area of micro-active carbon of 200 mesh and 80 mesh is 1954.95 m2g-1 and 1516.34 m2g-1.

Adsorption and conformational modification of fibronectin and fibrinogen adsorbed on hydroxyapatite. A QCM-D study.

PubMed

Fernández-Montes Moraleda, Belén; San Román, Julio; Rodríguez-Lorenzo, Luís M

2016-10-01

Hydroxyapatite is a bioactive ceramic frequently used for bone engineering/replacement. One of the parameters that influence the biological response to implanted materials is the conformation of the first adsorbed protein layer. In this work, the adsorption and conformational changes of two fibroid serum proteins; fibronectin and fibrinogen adsorbed onto four different hydroxyapatite powders are studied with a Quartz Crystal Microbalance with Dissipation (QCM-D). Each of the calcined apatites adsorbs less protein than their corresponding synthesized samples. Adsorption on synthesized samples yields always an extended conformation whereas a reorganization of the layer is observed for the calcined samples. Fg acquires a "Side on" conformation in all the samples at the beginning of the experiment except for one of the synthesized samples where an "End-on" conformation is obtained during the whole experiment. The Extended conformation is the active conformation for Fn. This conformation is favored by apatites with large specific surface area (SSA) and on highly concentrated media. Apatite surface features should be considered in the selection or design of materials for bone regeneration, since it is possible to control the conformation mode of attachment of Fn and Fg by an appropriate selection of them. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2585-2594, 2016. © 2016 Wiley Periodicals, Inc.

Mustard plant ash: a source of micronutrient and an adsorbent for removal of 2,4-dichlorophenoxyacetic acid.

PubMed

Trivedi, Nikhilesh S; Mandavgane, Sachin A; Kulkarni, Bhaskar D

2016-10-01

The work highlights the utilization of an agricultural waste mustard plant ash (MPA) as a soil additive and an adsorbent. MPA was characterized by X-ray fluorescence (XRF), energy-dispersive X-ray spectroscopy (EDX), proximate analysis, CHNS analysis, Brunauer-Emmett-Teller (BET) surface area analysis, zeta potential measurements, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRF analysis confirmed the presence of CaO (31.35 %), K 2 O (18.55 %), and P 2 O 5 (6.99 %), all of which act as micronutrients to plants. EDX also confirms high amount of elemental O, Ca, K, and P. The adsorptive ability of MPA was investigated using a commonly used herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), as a representative chemical. Batch adsorption experiments were conducted to study the effect of different operational parameters such as adsorbent dose, initial 2,4-D concentration, contact time, and temperature on the adsorption process. Data from experiments were fitted to various kinetic and isothermal models. The pseudo-second-order kinetic model was found to show the best fit (R 2  > 0.99), with the highest k 2 value of the order 10 5 . Based on the study results, dosage of MPA/hectare for different crops has been recommended for effective removal of 2,4-D. To our knowledge, this is the first study in which MPA has been characterized in detail and investigated for dual applications (as an adsorbent and as a soil additive).

Diffusion in confinement: kinetic simulations of self- and collective diffusion behavior of adsorbed gases

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

Abouelnasr, MKF; Smit, B

2012-01-01

The self- and collective-diffusion behaviors of adsorbed methane, helium, and isobutane in zeolite frameworks LTA, MFI, AFI, and SAS were examined at various concentrations using a range of molecular simulation techniques including Molecular Dynamics (MD), Monte Carlo (MC), Bennett-Chandler (BC), and kinetic Monte Carlo (kMC). This paper has three main results. (1) A novel model for the process of adsorbate movement between two large cages was created, allowing the formulation of a mixing rule for the re-crossing coefficient between two cages of unequal loading. The predictions from this mixing rule were found to agree quantitatively with explicit simulations. (2) Amore » new approach to the dynamically corrected Transition State Theory method to analytically calculate self-diffusion properties was developed, explicitly accounting for nanoscale fluctuations in concentration. This approach was demonstrated to quantitatively agree with previous methods, but is uniquely suited to be adapted to a kMC simulation that can simulate the collective-diffusion behavior. (3) While at low and moderate loadings the self- and collective-diffusion behaviors in LTA are observed to coincide, at higher concentrations they diverge. A change in the adsorbate packing scheme was shown to cause this divergence, a trait which is replicated in a kMC simulation that explicitly models this behavior. These phenomena were further investigated for isobutane in zeolite MFI, where MD results showed a separation in self- and collective-diffusion behavior that was reproduced with kMC simulations.« less

Diffusion in confinement: kinetic simulations of self- and collective diffusion behavior of adsorbed gases.

PubMed

Abouelnasr, Mahmoud K F; Smit, Berend

2012-09-07

The self- and collective-diffusion behaviors of adsorbed methane, helium, and isobutane in zeolite frameworks LTA, MFI, AFI, and SAS were examined at various concentrations using a range of molecular simulation techniques including Molecular Dynamics (MD), Monte Carlo (MC), Bennett-Chandler (BC), and kinetic Monte Carlo (kMC). This paper has three main results. (1) A novel model for the process of adsorbate movement between two large cages was created, allowing the formulation of a mixing rule for the re-crossing coefficient between two cages of unequal loading. The predictions from this mixing rule were found to agree quantitatively with explicit simulations. (2) A new approach to the dynamically corrected Transition State Theory method to analytically calculate self-diffusion properties was developed, explicitly accounting for nanoscale fluctuations in concentration. This approach was demonstrated to quantitatively agree with previous methods, but is uniquely suited to be adapted to a kMC simulation that can simulate the collective-diffusion behavior. (3) While at low and moderate loadings the self- and collective-diffusion behaviors in LTA are observed to coincide, at higher concentrations they diverge. A change in the adsorbate packing scheme was shown to cause this divergence, a trait which is replicated in a kMC simulation that explicitly models this behavior. These phenomena were further investigated for isobutane in zeolite MFI, where MD results showed a separation in self- and collective- diffusion behavior that was reproduced with kMC simulations.

Towards understanding KOH conditioning of amidoxime-based oolymer adsorbents for sequestering uranium from seawater

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

Pan, Horng-Bin; Kuo, Li-Jung; Wood, Jordana

2015-11-17

Conditioning of polymer fiber adsorbents grafted with amidoxime and carboxylic acid groups is necessary to make the materials hydrophilic for sequestering uranium from seawater. In this paper, spectroscopic techniques were employed to study the effectiveness of the traditional KOH conditioning method (2.5% KOH at 80⁰C) on recently developed high-surface-area amidoxime-based polymer fiber adsorbents developed at Oak Ridge National Laboratory. FTIR spectra reveal that the KOH conditioning process removes the proton from the carboxylic acids and also converts the amidoxime groups to carboxylate groups in the adsorbent. With prolonged KOH treatment (>1 hr) at 80⁰C, physical damage to the adsorbent materialmore » occurs which can lead to a significant reduction in the adsorbent's uranium adsorption capability in real seawater during extended exposure times (>21 days). The physical damage to the adsorbent can be minimized by lowering KOH conditioning temperature. For the high-surface-area amidoxime-based adsorbents, 20 min of conditioning in 2.5% KOH at 80⁰C or 1 hr of conditioning in 2.5% KOH at 60⁰C appears sufficient to achieve de-protonation of the carboxylic acid with minimal harmful effects to the adsorbent material. Lastly, the use of NaOH instead of KOH can also reduce the cost of the base treatment process required for conditioning the amidoxime-based sorbents with minimal loss of adsorption capacity (≤7%).« less

[Concentrated adsorbed, cultured antirabies vaccine].

PubMed

Dulina, A V; Shafeeva, R S; Morogova, V M; Krutilina, D V; Nigamov, F N

1980-11-01

In animal experiments the antigenic activity of adsorbed concentrated tissue-culture rabies vaccine was shown to be significantly higher in comparison with the nonadsorbed concentrated preparation when introduced in 2 intramuscular injections at an interval of 21 and 30 days, as well as in comparison with commercial tissue-culture vaccine when introduced subcutaneously in a 14-day course of daily injections.

Chitosan-coated mesoporous microspheres of calcium silicate hydrate: environmentally friendly synthesis and application as a highly efficient adsorbent for heavy metal ions.

PubMed

Zhao, Jing; Zhu, Ying-Jie; Wu, Jin; Zheng, Jian-Qiang; Zhao, Xin-Yu; Lu, Bing-Qiang; Chen, Feng

2014-03-15

Chitosan-coated calcium silicate hydrate (CSH/chitosan) mesoporous microspheres formed by self-assembly of nanosheets have been synthesized in aqueous solution under ambient conditions without using any toxic surfactant or organic solvent. The method reported herein has advantages of simplicity, low cost and being environmentally friendly. The BET specific surface area of CSH/chitosan mesoporous microspheres is measured to be as high as ~356 m(2) g(-1), which is considerably high among calcium silicate materials. The as-prepared CSH/chitosan mesoporous microspheres are promising adsorbent and exhibit a quick and highly efficient adsorption behavior toward heavy metal ions of Ni(2+), Zn(2+), Cr(3+), Pb(2+) Cu(2+) and Cd(2+) in aqueous solution. The adsorption kinetics can be well fitted by the pseudo second-order model. The maximum adsorption amounts of Ni(2+), Zn(2+), Pb(2+), Cu(2+) and Cd(2+) on CSH/chitosan mesoporous microspheres are extremely high, which are 406.6, 400, 796, 425 and 578 mg/g, respectively. The CSH/chitosan adsorbent exhibits the highest affinity for Pb(2+) ions among five heavy metal ions. The adsorption capacities of the CSH/chitosan adsorbent toward heavy metal ions are relatively high compared with those reported in the literature. Copyright © 2013 Elsevier Inc. All rights reserved.

ε-Polylysine-based thermo-responsive adsorbents for immunoglobulin adsorption-desorption under mild conditions.

PubMed

Maruyama, Masashi; Shibuya, Keisuke

2017-08-22

Thermo-responsive adsorbents for immunoglobulin G (IgG) employing ε-polylysine (EPL) as a polymer backbone were developed. The introduction of mercaptoethylpyridine (MEP) as an IgG-binding ligand and hydrophobization of side chains afforded thermo-responsive IgG adsorbents, whose thermo-responsive IgG desorption ratio was up to 88% (EPL/MEP derivative 3m). The changes in surface densities of active MEP groups, which are caused by thermal conformational changes of the adsorbents, play key roles for IgG desorption. Although a trade-off of IgG adsorption capacity and IgG desorption ratio was observed, the present study offers a novel molecular design for thermo-responsive adsorbents with high synthetic accessibility and potentially low toxicity.

Comparing dissolved reactive phosphorus measured by DGT with ferrihydrite and titanium dioxide adsorbents: anionic interferences, adsorbent capacity and deployment time.

PubMed

Panther, Jared G; Teasdale, Peter R; Bennett, William W; Welsh, David T; Zhao, Huijun

2011-07-18

Two adsorbents (Metsorb and ferrihydrite) used in binding layers with the diffusive gradients in a thin film technique were evaluated for the measurement of dissolved reactive phosphorous (DRP) in synthetic and natural waters. Possible interferences were investigated with Cl(-) (up to 1.35 mol L(-1)) and SO(4)(2-) (up to 0.056 mol L(-1)) having no affect on either DGT binding layer, and HCO(3)(-) (up to 5.7 mmol L(-1)) having no effect on Metsorb-DGT, over 4 days. However, HCO(3)(-) interfered with the ferrihydrite-DGT measurement at concentrations typical of many natural waters (≥0.7 mmol L(-1)) after a deployment period of 1-2 days. The capacity of the Metsorb binding phase for DGT response was ∼37,000 ng P, whereas the capacities of a low-mass (17.8 mg of adsorbent per DGT sampler) and high-mass (29.2mg of adsorbent per DGT sampler) ferrihydrite binding phase were substantially lower (∼15,000 ng P and ∼25,000 ng P, low-mass and high-mass, respectively). Increasing the capacity of the ferrihydrite adsorbent allowed the ferrihydrite-DGT to be utilized for up to 3 days before interference by HCO(3)(-) was observed. Seawater deployments demonstrated that even high-capacity ferrihydrite-DGT devices underestimated the DRP concentration by 37%, whereas Metsorb-DGT measurements were accurate. The Metsorb-DGT is superior to the ferrihydrite-DGT for determining DRP over deployment times greater than 1 day and in waters with ≥0.7 mmol L(-1) HCO(3)(-). Based on the experience obtained from this detailed validation process, the authors propose a number of key requirements that need to be considered when developing new DGT binding layers, with testing the performance over longer deployment times being critical. Copyright © 2011 Elsevier B.V. All rights reserved.

Adsorbates in a Box: Titration of Substrate Electronic States

NASA Astrophysics Data System (ADS)

Cheng, Zhihai; Wyrick, Jonathan; Luo, Miaomiao; Sun, Dezheng; Kim, Daeho; Zhu, Yeming; Lu, Wenhao; Kim, Kwangmoo; Einstein, T. L.; Bartels, Ludwig

2010-08-01

Nanoscale confinement of adsorbed CO molecules in an anthraquinone network on Cu(111) with a pore size of ≈4nm arranges the CO molecules in a shell structure that coincides with the distribution of substrate confined electronic states. Molecules occupy the states approximately in the sequence of rising electron energy. Despite the sixfold symmetry of the pore boundary itself, the adsorbate distribution adopts the threefold symmetry of the network-substrate system, highlighting the importance of the substrate even for such quasi-free-electron systems.

Solid phase extraction of trace amounts of cadmium(II) ions in water and food samples using iron magnetite nanoparticles modified by sodium dodecyl sulfate and 2-mercaptobenzothiazole.

PubMed

Abbasi, Shahriar; ShanbehDehbalai, Mehdi; Khani, Hossein

2017-03-01

A new, simple and rapid method for solid phase extraction and preconcentration of trace amounts of cadmium ions using 2-mercaptobenzothiazole/sodium dodecyl sulfate immobilized on magnetite nanoparticles (MBT-SDS-MNPs) was proposed. The method is based on the extraction of cadmium ions via complexation with MBT immobilized on SDS-coated MNPs and their determination by flame atomic absorption spectrometry. The effects of different parameters - pH; eluent type, concentration and volume; amounts of salt and adsorbent; contact time and interfering ions - on the adsorption of cadmium ions were studied. Under optimized conditions, the calibration curve was linear in the range of 10-5,000 μg L -1 . Detection limit and relative standard deviation of the proposed method were 0.009 μg L -1 and 2.2%, respectively. The adsorption data were analyzed by Langmuir and Freundlich isotherm models and a maximum adsorption amount of 24.80 mg g -1 , a Langmuir adsorption equilibrium constant (b) of 4.62 and Freundlich constants K f and n of 6.075 mg 1-1/n L 1/n g -1 and 2.391, respectively, were obtained. Finally, this adsorbent was successfully used for extraction of cadmium from water and food samples.

Monitoring by Control Technique - Activated Carbon Adsorber

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about Activated Carbon Adsorber control techniques used to reduce pollutant emissions.

Microwave-assisted activated carbon from cocoa shell as adsorbent for removal of sodium diclofenac and nimesulide from aqueous effluents.

PubMed

Saucier, Caroline; Adebayo, Matthew A; Lima, Eder C; Cataluña, Renato; Thue, Pascal S; Prola, Lizie D T; Puchana-Rosero, M J; Machado, Fernando M; Pavan, Flavio A; Dotto, G L

2015-05-30

Microwave-induced chemical activation process was used to prepare an activated carbon from cocoa shell for efficient removal of two anti-inflammatories, sodium diclofenac (DFC) and nimesulide (NM), from aqueous solutions. A paste was obtained from a mixture of cocoa shell and inorganic components; with a ratio of inorganic: organic of 1 (CSC-1.0). The mixture was pyrolyzed in a microwave oven in less than 10 min. The CSC-1.0 was acidified with a 6 mol L(-1) HCl under reflux to produce MWCS-1.0. The CSC-1.0 and MWCS-1.0 were characterized using FTIR, SEM, N2 adsorption/desorption curves, X-ray diffraction, and point of zero charge (pHpzc). Experimental variables such as initial pH of the adsorbate solutions and contact time were optimized for adsorptive characteristics of MWCS-1.0. The optimum pH for removal of anti-inflammatories ranged between 7.0 and 8.0. The kinetic of adsorption was investigated using general order, pseudo first-order and pseu do-second order kinetic models. The maximum amounts of DCF and NM adsorbed onto MWCS-1.0 at 25 °C are 63.47 and 74.81 mg g(-1), respectively. The adsorbent was tested on two simulated hospital effluents. MWCS-1.0 is capable of efficient removal of DCF and NM from a medium that contains high sugar and salt concentrations. Copyright © 2015 Elsevier B.V. All rights reserved.

The Density and Refractive Index of Adsorbing Protein Layers

PubMed Central

Vörös, Janos

2004-01-01

The structure of the adsorbing layers of native and denatured proteins (fibrinogen, γ-immunoglobulin, albumin, and lysozyme) was studied on hydrophilic TiO2 and hydrophobic Teflon-AF surfaces using the quartz crystal microbalance with dissipation and optical waveguide lightmode spectroscopy techniques. The density and the refractive index of the adsorbing protein layers could be determined from the complementary information provided by the two in situ instruments. The observed density and refractive index changes during the protein-adsorption process indicated the presence of conformational changes (e.g., partial unfolding) in general, especially upon contact with the hydrophobic surface. The structure of the formed layers was found to depend on the size of the proteins and on the experimental conditions. On the TiO2 surface smaller proteins formed a denser layer than larger ones and the layer of unfolded proteins was less dense than that adsorbed from the native conformation. The hydrophobic surface induced denaturation and resulted in the formation of thin compact protein films of albumin and lysozyme. A linear correlation was found between the quartz crystal microbalance measured dissipation factor and the total water content of the layer, suggesting the existence of a dissipative process that is related to the solvent molecules present inside the adsorbed protein layer. Our measurements indicated that water and solvent molecules not only influence the 3D structure of proteins in solution but also play a crucial role in their adsorption onto surfaces. PMID:15240488

Preparation and performance of arsenate (V) adsorbents derived from concrete wastes.

PubMed

Sasaki, Takeshi; Iizuka, Atsushi; Watanabe, Masayuki; Hongo, Teruhisa; Yamasaki, Akihiro

2014-10-01

Solid adsorbent materials, prepared from waste cement powder and concrete sludge were assessed for removal of arsenic in the form of arsenic (As(V)) from water. All the materials exhibited arsenic removal capacity when added to distilled water containing 10-700 mg/L arsenic. The arsenic removal isotherms were expressed by the Langmuir type equations, and the highest removal capacity was observed for the adsorbent prepared from concrete sludge with heat treatment at 105°C, the maximum removal capacity being 175 mg-As(V)/g. Based on changes in arsenic and calcium ion concentrations, and solution pH, the removal mechanism for arsenic was considered to involve the precipitation of calcium arsenate, Ca3(AsO4)2. The enhanced removal of arsenic for the adsorbent prepared from concrete sludge with heat treatment was thought to reflect ion exchange by ettringite. The prepared adsorbents, derived from waste cement and concrete using simple procedures, may offer a cost effective approach for arsenic removal and clean-up of contaminated waters, especially in developing countries. Copyright © 2014 Elsevier Ltd. All rights reserved.

Supercritical fluid regeneration of adsorbents

NASA Astrophysics Data System (ADS)

Defilippi, R. P.; Robey, R. J.

1983-05-01

The results of a program to perform studies supercritical (fluid) carbon dioxide (SCF CO2) regeneration of adsorbents, using samples of industrial wastewaters from manufacturing pesticides and synthetic solution, and to estimate the economics of the specific wastewater treatment regenerations, based on test data are given. Processing costs for regenerating granular activated carbon GAC) for treating industrial wastewaters depend on stream properties and regeneration throughput.

Nonadiabatic dynamics of electron scattering from adsorbates in surface bands

NASA Astrophysics Data System (ADS)

Gumhalter, Branko; Šiber, Antonio; Buljan, Hrvoje; Fauster, Thomas

2008-10-01

We present a comparative study of nonadiabatic dynamics of electron scattering in quasi-two-dimensional surface band which is induced by the long-range component of the interactions with a random array of adsorbates. Using three complementary model descriptions of intraband spatiotemporal propagation of quasiparticles that go beyond the single-adsorbate scattering approach we are able to identify distinct subsequent regimes of evolution of an electron following its promotion into an unoccupied band state: (i) early quadratic or ballistic decay of the initial-state survival probability within the Heisenberg uncertainty window, (ii) preasymptotic exponential decay governed by the self-consistent Fermi golden rule scattering rate, and (iii) asymptotic decay described by a combined inverse power-law and logarithmic behavior. The developed models are applied to discuss the dynamics of intraband adsorbate-induced scattering of hot electrons excited into the n=1 image-potential band on Cu(100) surface during the first stage of a two-photon photoemission process. Estimates of crossovers between the distinct evolution regimes enable assessments of the lifespan of a standard quasiparticle behavior and thereby of the range of applicability of the widely used Fermi golden rule and optical Bloch equations approach for description of adsorbate-induced quasiparticle decay and dephasing in ultrafast experiments.

Ozonation of isoproturon adsorbed on silica particles under atmospheric conditions

NASA Astrophysics Data System (ADS)

Pflieger, Maryline; Grgić, Irena; Kitanovski, Zoran

2012-12-01

The results on heterogeneous ozonation of a phenylurea pesticide, isoproturon, under atmospheric conditions are presented for the first time in the present study. The study was carried out using an experimental device previously adopted and validated for the heterogeneous reactivity of organics toward ozone (Pflieger et al., 2011). Isoproturon was adsorbed on silica particles via a liquid-to-solid equilibrium with a load far below a monolayer (0.02% by weight/surface coverage of 0.5%). The rate constants were estimated by measuring the consumption of the organic (dark, T = 26 °C, RH < 1%). The experimental data were fitted by both the modified Langmuir-Hinshelwood and the Eley-Rideal patterns, resulting in atmospheric lifetimes of heterogeneous ozonation of 4 and 6 days, respectively (for 40 ppb of O3). Parameters, such as the number and the quantity of pesticides adsorbed on the solid support, which can significantly influence the heterogeneous kinetics, were investigated as well. The results obtained suggest that the organic compound is adsorbed in multilayer aggregates on the aerosol even though submonolayer coverage is assumed. The presence of a second herbicide, trifluralin, together with isoproturon on the aerosol surface does not affect the kinetics of ozonation, indicating that both compounds are adsorbed on different surface sites of silica particles.

A Method for Field Calibration of the PA260 Phosphorus Analyzer Using Solid Adsorbent Materials

DTIC Science & Technology

1989-12-01

plant environment. The solid adsorbent approach has two major advantages over other traditional air sampling devices such as bubblers or impingers...GC (60/80 mesh) or Chromosorb 106 (80/100 mesh). Both adsorbents were supplied by Alltech Associates (Deerfield, IL). The adsorbents were packed in

Heterogeneous Reactions of Limonene on Mineral Dust: Impacts of Adsorbed Water and Nitric Acid.

PubMed

Lederer, Madeline R; Staniec, Allison R; Coates Fuentes, Zoe L; Van Ry, Daryl A; Hinrichs, Ryan Z

2016-12-08

Biogenic volatile organic compounds (BVOCs), including the monoterpene limonene, are a major source of secondary organic aerosol (SOA). While gas-phase oxidation initiates the dominant pathway for BVOC conversion to SOA, recent studies have demonstrated that biogenic hydrocarbons can also directly react with acidic droplets. To investigate whether mineral dust may facilitate similar reactive uptake of biogenic hydrocarbons, we studied the heterogeneous reaction of limonene with mineral substrates using condensed-phase infrared spectroscopy and identified the formation of irreversibly adsorbed organic products. For kaolinite, Arizona Test Dust, and silica at 30% relative humidity, GC-MS identified limonene-1,2-diol as the dominant product with total organic surface concentrations on the order of (3-5) × 10 18 molecules m -2 . Experiments with 18 O-labeled water support a mechanism initiated by oxidation of limonene by surface redox sites forming limonene oxide followed by water addition to the epoxide to form limonenediol. Limonene uptake on α-alumina, γ-alumina, and montmorillonite formed additional products in high yield, including carveol, carvone, limonene oxide, and α-terpineol. To model tropospheric processing of mineral aerosol, we also exposed each mineral substrate to gaseous nitric acid prior to limonene uptake and identified similar surface adsorbed products that were formed at rates 2 to 5 times faster than without nitrate coatings. The initial rate of reaction was linearly dependent on gaseous limonene concentration between 5 × 10 12 and 5 × 10 14 molecules cm -3 (0.22-20.5 ppm) consistent with an Eley-Rideal-type mechanism in which gaseous limonene reacts directly with reactive surface sites. Increasing relative humidity decreased the amount of surface adsorbed products indicating competitive adsorption of surface adsorbed water. Using a laminar flow tube reactor we measured the uptake coefficient for limonene on kaolinite at 25% RH to range from

Advanced wide-field surface plasmon microscopy of single adsorbing nanoparticles

NASA Astrophysics Data System (ADS)

Nizamov, Shavkat; Scherbahn, Vitali; Mirsky, Vladimir M.

2017-05-01

In-situ detection and characterization of nanoparticles in biological media as well as in food or other complex samples is still a big challenge for existing analytical methods. Here we describe a label-free and cost-effective analytical method for detection of nanoparticles in the concentration range 106 -1010 NPs/ml. The proposed method is based on the surface plasmon resonance microscopy (SPRM) with a large field of view ( 1.3mm2 ). It is able to detect and count adsorbing nanoparticles individually, totally up to the hundreds of thousands of NPs on the sensor surface. At constant diffusion conditions the detection rate is proportional to the number concentration of NPs, this provides an approach to determine the NPs concentration. The adsorption of nanoparticle can be manipulated by the surface functionalization, pH and electrolyte concentration of suspensions. Images of detected nanoparticles can be quantified in order to characterize them individually. The image intensity grows quasi-linearly with nanoparticle size for the given material. However, the size and material of nanoparticle cannot be resolved directly from the image. For determination of chemical composition, SPRM can be assisted by electrochemical analysis. In this case, the gold sensor surface is used both as a resonant media for plasmon microscopy and as a working electrode. Under potential sweep, the adsorbed NPs can be subjected to electrochemical dissolution, which is detected optically. The potential of this conversion characterizes the material of NPs.

Oxidation of adsorbed ferrous iron: kinetics and influence of process conditions.

PubMed

Buamah, R; Petrusevski, B; Schippers, J C

2009-01-01

For the removal of iron from groundwater, aeration followed with rapid (sand) filtration is frequently applied. Iron removal in this process is achieved through oxidation of Fe(2 + ) in aqueous solution followed by floc formation as well as adsorption of Fe(2 + ) onto the filter media. The rate of oxidation of the adsorbed Fe(2 + ) on the filter media plays an important role in this removal process. This study focuses on investigating the effect of pH on the rate of oxidation of adsorbed Fe(2 + ). Fe(2 + ) has been adsorbed, under anoxic conditions, on iron oxide coated sand (IOCS) in a short filter column and subsequently oxidized by feeding the column with aerated water. Ferrous ions adsorbed at pH 5, 6, 7 and 8 demonstrated consumption of oxygen, when aerated water was fed into the column. The oxygen uptake at pH 7 and 8 was faster than at pH 5 and 6. However the difference was less pronounced than expected. The difference is attributed to the pH buffering effect of the IOCS. At feedwater pH 5, 6 and 7 the pH in the effluent was higher than in the influent, while a pH drop should occur because of oxidation of adsorbed Fe(2 + ). At pH 8, the pH dropped. These phenomena are attributed to the presence of calcium and /or ferrous carbonate in IOCS.

Quantification of the Influence of Protein-Protein Interactions on Adsorbed Protein Structure and Bioactivity

PubMed Central

Wei, Yang; Thyparambil, Aby A.; Latour, Robert A.

2013-01-01

While protein-surface interactions have been widely studied, relatively little is understood at this time regarding how protein-surface interaction effects are influenced by protein-protein interactions and how these effects combine with the internal stability of a protein to influence its adsorbed-state structure and bioactivity. The objectives of this study were to develop a method to study these combined effects under widely varying protein-protein interaction conditions using hen egg-white lysozyme (HEWL) adsorbed on silica glass, poly(methyl methacrylate), and polyethylene as our model systems. In order to vary protein-protein interaction effects over a wide range, HEWL was first adsorbed to each surface type under widely varying protein solution concentrations for 2 h to saturate the surface, followed by immersion in pure buffer solution for 15 h to equilibrate the adsorbed protein layers in the absence of additionally adsorbing protein. Periodic measurements were made at selected time points of the areal density of the adsorbed protein layer as an indicator of the level of protein-protein interaction effects within the layer, and these values were then correlated with measurements of the adsorbed protein’s secondary structure and bioactivity. The results from these studies indicate that protein-protein interaction effects help stabilize the structure of HEWL adsorbed on silica glass, have little influence on the structural behavior of HEWL on HDPE, and actually serve to destabilize HEWL’s structure on PMMA. The bioactivity of HEWL on silica glass and HDPE was found to decrease in direct proportion to the degree of adsorption-induce protein unfolding. A direct correlation between bioactivity and the conformational state of adsorbed HEWL was less apparent on PMMA, thus suggesting that other factors influenced HEWL’s bioactivity on this surface, such as the accessibility of HEWL’s bioactive site being blocked by neighboring proteins or the surface

The role of adsorbed water on the friction of a layer of submicron particles

USGS Publications Warehouse

Sammis, Charles G.; Lockner, David A.; Reches, Ze’ev

2011-01-01

Anomalously low values of friction observed in layers of submicron particles deformed in simple shear at high slip velocities are explained as the consequence of a one nanometer thick layer of water adsorbed on the particles. The observed transition from normal friction with an apparent coefficient near μ = 0.6 at low slip speeds to a coefficient near μ = 0.3 at higher slip speeds is attributed to competition between the time required to extrude the water layer from between neighboring particles in a force chain and the average lifetime of the chain. At low slip speeds the time required for extrusion is less than the average lifetime of a chain so the particles make contact and lock. As slip speed increases, the average lifetime of a chain decreases until it is less than the extrusion time and the particles in a force chain never come into direct contact. If the adsorbed water layer enables the otherwise rough particles to rotate, the coefficient of friction will drop to μ = 0.3, appropriate for rotating spheres. At the highest slip speeds particle temperatures rise above 100°C, the water layer vaporizes, the particles contact and lock, and the coefficient of friction rises to μ = 0.6. The observed onset of weakening at slip speeds near 0.001 m/s is consistent with the measured viscosity of a 1 nm thick layer of adsorbed water, with a minimum particle radius of approximately 20 nm, and with reasonable assumptions about the distribution of force chains guided by experimental observation. The reduction of friction and the range of velocities over which it occurs decrease with increasing normal stress, as predicted by the model. Moreover, the analysis predicts that this high-speed weakening mechanism should operate only for particles with radii smaller than approximately 1 μm. For larger particles the slip speed required for weakening is so large that frictional heating will evaporate the adsorbed water and weakening will not occur.

Investigation on removal of malachite green using EM based compost as adsorbent.

PubMed

Bhagavathi Pushpa, T; Vijayaraghavan, J; Sardhar Basha, S J; Sekaran, V; Vijayaraghavan, K; Jegan, J

2015-08-01

The discarded materials from different sources can be utilized as effective materials in wastewater remediation. This proposed study was aimed mainly to investigate the possibility of Effective Microorganisms based compost (EMKC), which is derived from the kitchen solid waste, as a non-conventional low cost adsorbent for the removal of malachite green from aqueous solution. Batch experiments were carried out to evaluate the optimum operating parameters like pH (2-9), initial dye concentration (50-1000mg/L), adsorbent particle size (0.6-2.36mm) and adsorbent dosage (2-12g/L). EMKC recorded maximum uptake of 136.6mg/g of MG at pH 8, initial dye concentration 1000mg/L, adsorbent particle size 1.18mm and adsorbent dosage 4g/L. Two and three parameter adsorption models were employed to describe experimental biosorption isotherm data. The results revealed that the Sips model resulted in better fit than other models. The pseudo-first and -second order models were applied to describe kinetic data, of which the pseudo-second order described experimental data better with high correlation coefficient. This investigation suggested that EMKC could be an effective and low cost material for the removal of malachite green dye from aqueous solution. Copyright © 2015 Elsevier Inc. All rights reserved.

Heat capacity of xenon adsorbed on nanobundle grooves

NASA Astrophysics Data System (ADS)

Chishko, K. A.; Sokolova, E. S.

2016-02-01

A model of a one-dimensional nonideal gas in an external transverse force field is used to interpret the experimentally observed thermodynamic properties of xenon deposited in grooves on the surface of carbon nanobundles. A nonideal gas model with pairwise interactions is not entirely adequate for describing dense adsorbates (at low temperatures), but makes it easy to account for the exchange of particles between the 1D adsorbate and the 3D atmosphere, which is an important factor at intermediate (on the order of 35 K for xenon) and, especially, high (˜100 K) temperatures. In this paper, we examine a 1D real gas taking only the one-dimensional Lennard-Jones interaction into account, but under exact equilibrium with respect to the number of particles between the 1D adsorbate and the 3D atmosphere of the measurement cell. The low-temperature branch of the specific heat is fitted independently by an elastic chain model so as to obtain the best agreement between theory and experiment over the widest possible region, beginning at zero temperature. The gas approximation sets in after temperatures for which the phonon specific heat of the chain essentially transforms to a one-dimensional equipartition law. Here the basic parameters of both models can be chosen so that the heat capacity C(T) of the chain transforms essentially continuously into the corresponding curve for the gas approximation. Thus, it can be expected that an adequate interpretation of the real temperature dependences of the specific heat of low-dimensionality atomic adsorbates can be obtained through a reasonable combination of the phonon and gas approximations. The main parameters of the gas approximation (such as the desorption energy) obtained by fitting the theory to experiments on the specific heat of xenon correlate well with published data.

Selective removal of caffeine from tea extracts using macroporous crosslinked polyvinyl alcohol adsorbents.

PubMed

Ma, Ning; Wang, Peng; Kong, Xia; Shi, Rongfu; Yuan, Zhi; Wang, Chunhong

2012-01-01

The hydrolysis reaction of ester groups in vinyl acetate (VAc) was used to introduce hydroxyl groups into the matrix of a macroporous adsorbent, which was itself prepared by free radical suspension copolymerization of triallyl isocyanurate (TAIC) and VAc. Therefore, the copolymerization incompatibility between the hydrophilic and the hydrophobic monomer was overcome successfully and the hydrophobic matrix of the polymeric adsorbent containing a polyvinyl alcohol (PVA) segment was obtained. Introduction of the PVA segment decreased the hydrophobic adsorption affinity of the adsorbent while producing the hydrogen-bonding interaction. When isolating the two active components, polyphenols (TPh) and caffeine (CAF), from green tea extracts, this polymeric adsorbent, namely poly(TAIC-co-VA), exhibited good adsorption selectivity towards TPh over CAF. The adsorption mechanism leading to this selectivity involved a hydrophobic interaction mechanism for CAF and multiple weak hydrophobic and hydrogen-bonding interactions for TPh. The adsorption thermodynamics for TPh on poly(TAIC-co-VA) were studied. The effects of adsorbent structure and gradient desorption conditions on isolation were investigated. The result showed that adsorbent, with 20% TAIC content, was able to efficiently remove CAF from different tea extracts with different ratios of TPh and CAF. Finally, almost no CAF was detected in the TPh fraction and the recovery of TPh was greater than 95%. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bicarbonate Elution of Uranium from Amidoxime-Based Polymer Adsorbents for Sequestering Uranium from Seawater

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

Pan, Horng-Bin; Wai, Chien M.; Kuo, Li-Jung

Uranium adsorbed on amidoxime-based polyethylene fibers in simulated seawater can be quantitatively eluted using 3 M KHCO3 at 40°C. Thermodynamic calculations are in agreement with the experimental observation that at high bicarbonate concentrations (3 M) uranyl ions bound to amidoxime molecules are converted to uranyl tris-carbonato complex in the aqueous solution. The elution process is basically the reverse reaction of the uranium adsorption process which occurs at a very low bicarbonate concentration (~10-3 M) in seawater. In real seawater experiments, the bicarbonate elution is followed by a NaOH treatment to remove natural organic matter adsorbed on the polymer adsorbent. Usingmore » the sequential bicarbonate and NaOH elution, the adsorbent is reusable after rinsing with deionized water and the recycled adsorbent shows no loss of uranium loading capacity based on real seawater experiments.« less

Bicarbonate Elution of Uranium from Amidoxime-Based Polymer Adsorbents for Sequestering Uranium from Seawater

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

Pan, Horng-Bin; Wai, Chien M.; Kuo, Li-Jung

Uranium adsorbed on amidoxime-based polyethylene fibers in simulated seawater can be quantitatively eluted using 3 M KHCO 3 at 40°C. Thermodynamic calculations are in agreement with the experimental observation that at high bicarbonate concentrations (3 M) uranyl ions bound to amidoxime molecules are converted to uranyl tris-carbonato complex in the aqueous solution. The elution process is basically the reverse reaction of the uranium adsorption process which occurs at a very low bicarbonate concentration (~10 -3 M) in seawater. The bicarbonate elution is followed by a NaOH treatment to remove natural organic matter adsorbed on the polymer adsorbent, in real seawatermore » experiments. Furthermore, by using the sequential bicarbonate and NaOH elution, the adsorbent is reusable after rinsing with deionized water and the recycled adsorbent shows no loss of uranium loading capacity based on real seawater experiments.« less

Bicarbonate Elution of Uranium from Amidoxime-Based Polymer Adsorbents for Sequestering Uranium from Seawater

DOE PAGES

Pan, Horng-Bin; Wai, Chien M.; Kuo, Li-Jung; ...

2017-05-02

Uranium adsorbed on amidoxime-based polyethylene fibers in simulated seawater can be quantitatively eluted using 3 M KHCO 3 at 40°C. Thermodynamic calculations are in agreement with the experimental observation that at high bicarbonate concentrations (3 M) uranyl ions bound to amidoxime molecules are converted to uranyl tris-carbonato complex in the aqueous solution. The elution process is basically the reverse reaction of the uranium adsorption process which occurs at a very low bicarbonate concentration (~10 -3 M) in seawater. The bicarbonate elution is followed by a NaOH treatment to remove natural organic matter adsorbed on the polymer adsorbent, in real seawatermore » experiments. Furthermore, by using the sequential bicarbonate and NaOH elution, the adsorbent is reusable after rinsing with deionized water and the recycled adsorbent shows no loss of uranium loading capacity based on real seawater experiments.« less

Effect of Solid to Liquid Ratio on Heavy Metal Removal by Geopolymer-Based Adsorbent

NASA Astrophysics Data System (ADS)

Ariffin, N.; Abdullah, M. M. A. B.; Arif Zainol, M. R. R. Mohd; Baltatu, M. S.; Jamaludin, L.

2018-06-01

Microstructure of three-dimensional aluminosilicate which similar to zeolite cause geopolymer based adsorbent accepted in the treatment of wastewater. This paper presents an investigation on the copper removal from the wastewater by varying the solid to liquid ratio in the fly ash, kaolin and sludge-based geopolymer adsorbent. The adsorption test was conducted to study the efficiency of the adsorbent and the copper concentration was examined by using Atomic Adsorption Spectrometry (AAS). The optimum solid to liquid ratio with the highest percentage removal were 1.0, 0.5 and 0.8 for fly ash-based geopolymer, kaolin-based geopolymer and sludge-based geopolymer adsorbent.

Empirical relationships between tree fall and landscape-level amounts of logging and fire

PubMed Central

Blanchard, Wade; Blair, David; McBurney, Lachlan; Stein, John; Banks, Sam C.

2018-01-01

Large old trees are critically important keystone structures in forest ecosystems globally. Populations of these trees are also in rapid decline in many forest ecosystems, making it important to quantify the factors that influence their dynamics at different spatial scales. Large old trees often occur in forest landscapes also subject to fire and logging. However, the effects on the risk of collapse of large old trees of the amount of logging and fire in the surrounding landscape are not well understood. Using an 18-year study in the Mountain Ash (Eucalyptus regnans) forests of the Central Highlands of Victoria, we quantify relationships between the probability of collapse of large old hollow-bearing trees at a site and the amount of logging and the amount of fire in the surrounding landscape. We found the probability of collapse increased with an increasing amount of logged forest in the surrounding landscape. It also increased with a greater amount of burned area in the surrounding landscape, particularly for trees in highly advanced stages of decay. The most likely explanation for elevated tree fall with an increasing amount of logged or burned areas in the surrounding landscape is change in wind movement patterns associated with cutblocks or burned areas. Previous studies show that large old hollow-bearing trees are already at high risk of collapse in our study area. New analyses presented here indicate that additional logging operations in the surrounding landscape will further elevate that risk. Current logging prescriptions require the protection of large old hollow-bearing trees on cutblocks. We suggest that efforts to reduce the probability of collapse of large old hollow-bearing trees on unlogged sites will demand careful landscape planning to limit the amount of timber harvesting in the surrounding landscape. PMID:29474487

Empirical relationships between tree fall and landscape-level amounts of logging and fire.

PubMed

Lindenmayer, David B; Blanchard, Wade; Blair, David; McBurney, Lachlan; Stein, John; Banks, Sam C

2018-01-01

Large old trees are critically important keystone structures in forest ecosystems globally. Populations of these trees are also in rapid decline in many forest ecosystems, making it important to quantify the factors that influence their dynamics at different spatial scales. Large old trees often occur in forest landscapes also subject to fire and logging. However, the effects on the risk of collapse of large old trees of the amount of logging and fire in the surrounding landscape are not well understood. Using an 18-year study in the Mountain Ash (Eucalyptus regnans) forests of the Central Highlands of Victoria, we quantify relationships between the probability of collapse of large old hollow-bearing trees at a site and the amount of logging and the amount of fire in the surrounding landscape. We found the probability of collapse increased with an increasing amount of logged forest in the surrounding landscape. It also increased with a greater amount of burned area in the surrounding landscape, particularly for trees in highly advanced stages of decay. The most likely explanation for elevated tree fall with an increasing amount of logged or burned areas in the surrounding landscape is change in wind movement patterns associated with cutblocks or burned areas. Previous studies show that large old hollow-bearing trees are already at high risk of collapse in our study area. New analyses presented here indicate that additional logging operations in the surrounding landscape will further elevate that risk. Current logging prescriptions require the protection of large old hollow-bearing trees on cutblocks. We suggest that efforts to reduce the probability of collapse of large old hollow-bearing trees on unlogged sites will demand careful landscape planning to limit the amount of timber harvesting in the surrounding landscape.

Treatment of Refinery Waste Water Using Environmental Friendly Adsorbent

NASA Astrophysics Data System (ADS)

Devi, M. Geetha; Al-Moshrafi, Samira Mohammed Khamis; Al Hudaifi, Alaa; Al Aisari, Buthaina Hamood

2017-12-01

This research evaluates the effectiveness of activated carbon prepared from walnut shell in the removal of pollutants from refinery waste water by adsorption technique. A series of batch experiments were carried out by varying the effluent solution pH, stirring time, stirring speed and adsorbent dosage in the reduction of pollutants from refinery effluent. Characterization of the adsorbent was performed using Scanning Electron Microscopy (SEM), Brunauer Emmett and Teller (BET) isotherm and Fourier Transform Infrared (FTIR) Spectroscopy. The best quality activated carbon was obtained with a particle size of 0.75 µm, activation temperature of 800 °C and activation time 24 h. The maximum BET surface area obtained was 165.2653 m2/g. The experimental results demonstrates that the highest percentage reduction in COD was 79%, using 0.6 g walnut shell powder at an optimum stirring speed of 100 rpm, at pH 6 and 120 min of contact time. The outcome of the result shows that walnut shell carbon is a potentially useful adsorbent for the removal of pollutants from refinery waste water.

Morin Flavonoid Adsorbed on Mesoporous Silica, a Novel Antioxidant Nanomaterial

PubMed Central

Arriagada, Francisco; Correa, Olosmira; Günther, Germán; Nonell, Santi; Mura, Francisco; Olea-Azar, Claudio

2016-01-01

Morin (2´,3, 4´,5,7-pentahydroxyflavone) is a flavonoid with several beneficial health effects. However, its poor water solubility and it sensitivity to several environmental factors avoid its use in applications like pharmaceutical and cosmetic. In this work, we synthetized morin-modified mesoporous silica nanoparticles (AMSNPs-MOR) as useful material to be used as potential nanoantioxidant. To achieve this, we characterized its adsorption kinetics, isotherm and the antioxidant capacity as hydroxyl radical (HO•) scavenger and singlet oxygen (1O2) quencher. The experimental data could be well fitted with Langmuir, Freundlich and Temkin isotherm models, besides the pseudo-second order kinetics model. The total quenching rate constant obtained for singlet oxygen deactivation by AMSNPs-MOR was one order of magnitude lower than the morin rate constant reported previously in neat solvents and lipid membranes. The AMSNPs-MOR have good antioxidant properties by itself and exhibit a synergic effect with morin on the antioxidant property against hydroxyl radical. This effect, in the range of concentrations studied, was increased when the amount of morin adsorbed increased. PMID:27812111

Astrocytes Specifically Remove Surface-Adsorbed Fibrinogen and Locally Express Chondroitin Sulfate Proteoglycans

PubMed Central

Hsiao, Tony W.; Swarup, Vimal P.; Kuberan, Balagurunathan; Tresco, Patrick A.; Hlady, Vladimir

2013-01-01

Surface-adsorbed fibrinogen (FBG) was recognized by adhering astrocytes and removed from the substrates in vitro by a two-phase removal process. The cells removed adsorbed FBG from binary proteins surface patterns (FBG + laminin, or FBG + albumin) while leaving the other protein behind. Astrocytes preferentially expressed chondroitin sulfate proteoglycan (CSPG) at the loci of fibrinogen stimuli; however no differences in overall CSPG production as a function of FBG surface coverage were identified. Removal of FBG by astrocytes was also found to be independent of transforming growth factor type β (TGF-β) receptor based signaling as cells maintained CSPG production in the presence of TGF-β receptor kinase inhibitor, SB 431542. The inhibitor decreased CSPG expression, but did not abolicsh it entirely. Because blood contact and subsequent FBG adsorption are unavoidable in neural implantations, the results indicate that implant-adsorbed FBG may contribute to reactive astrogliosis around the implant as astrocytes specifically recognize adsorbed FBG. PMID:23499985

Heating and cooling system for an on-board gas adsorbent storage vessel

DOEpatents

Tamburello, David A.; Anton, Donald L.; Hardy, Bruce J.; Corgnale, Claudio

2017-06-20

In one aspect, a system for controlling the temperature within a gas adsorbent storage vessel of a vehicle may include an air conditioning system forming a continuous flow loop of heat exchange fluid that is cycled between a heated flow and a cooled flow. The system may also include at least one fluid by-pass line extending at least partially within the gas adsorbent storage vessel. The fluid by-pass line(s) may be configured to receive a by-pass flow including at least a portion of the heated flow or the cooled flow of the heat exchange fluid at one or more input locations and expel the by-pass flow back into the continuous flow loop at one or more output locations, wherein the by-pass flow is directed through the gas adsorbent storage vessel via the by-pass line(s) so as to adjust an internal temperature within the gas adsorbent storage vessel.

Alternative Alkaline Conditioning of Amidoxime Based Adsorbent for Uranium Extraction from Seawater

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

Das, S.; Liao, W. -P.; Flicker Byers, M.

2016-04-20

Alkaline conditioning of the amidoxime based adsorbents is a significant step in the preparation of the adsorbent for uranium uptake from seawater. The effects of various alkaline conditioning parameters such as the type of alkaline reagent, reaction temperature, and reaction time were investigated with respect to uranium adsorption capacity from simulated seawater (spiked with 8 ppm uranium) and natural seawater (from Sequim Bay, WA). An adsorbent (AF1) was prepared at the Oak Ridge National Laboratory by radiation-induced graft polymerization (RIGP) with acrylonitrile and itaconic acid onto high-surface-area polyethylene fibers. For the AF1 adsorbent, sodium hydroxide emerged as a better reagentmore » for alkaline conditioning over potassium hydroxide, which has typically been used in previous studies, because of higher uranium uptake capacity and lower cost over the other candidate alkaline reagents investigated in this study. Use of sodium hydroxide in place of potassium hydroxide is shown to result in a 21-30% decrease in the cost of uranium recovery.« less

Graphene oxide/chitin nanofibril composite foams as column adsorbents for aqueous pollutants.

PubMed

Ma, Zhongshi; Liu, Dagang; Zhu, Yi; Li, Zehui; Li, Zhenxuan; Tian, Huafeng; Liu, Haiqing

2016-06-25

A novel graphene oxide/chitin nanofibrils (GO-CNF) composite foam as a column adsorbent was prepared for aqueous contaminant disposal. The structures, morphologies and properties of composite foams supported by nanofibrils were characterized. As a special case, the adsorption of methylene blue (MB) on GO-CNF was investigated regarding the static adsorption and column adsorption-desorption tests. Results from equilibrium adsorption isotherms indicated that the adsorption behavior was well-fitted to Langmuir model. The composite foams reinforced by CNF were dimensionally stable during the column adsorption process and could be reused after elution. The removal efficiency of MB was still nearly 90% after 3 cycles. Furthermore, other inorganic or organic pollutants adsorbed by composite foams were also explored. Therefore, this novel composite foam with remarkable properties such as dimensional stability, universal adsorbent for cationic pollutants, high adsorption capacity, and ease of regeneration was a desirable adsorbent in the future practical application of water pollutant treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Removal of salicylic acid as an emerging contaminant by a polar nano-dendritic adsorbent from aqueous media.

PubMed

Arshadi, M; Mousavinia, F; Abdolmaleki, M K; Amiri, M J; Khalafi-Nezhad, A

2017-05-01

A polar nano-dendritic adsorbent containing amine groups (SAPAMAA) was synthesized onto the nanoparticles of SiO 2 Al 2 O 3 and its uptake of salicylic acid (SA) from the synthetic and real water was investigated. The synthesized nanomaterials were fully studied by nuclear magnetic resonance spectrum ( 1 H NMR and 13 C NMR), Fourier transform infrared spectroscopy (FT-IR), zeta potential (ζ), inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and elemental analysis. Various parameters such as the effect of the contact time, adsorbent dosage, initial SA concentrations, effect of solution's temperature, interfering ions, the hydrophobicity of the nanoadsorbent and initial pH were assessed. The contact time to approach equilibrium for higher adsorption was 15min (252.8mgg -1 ). The isotherms could be fitted by Sips model (with the average relative error of 6.6) and the kinetic data could be characterized by pseudo-second-order rate equation (with the average relative error of 13.0), implying chemical adsorption as the ratelimiting step of uptake process which was supported by the experimental data from the effect of interfering ions, zeta potential, and altering of the adsorbent's hydrophobicity. The uptake capacities decreased with temperature increasing, and showed that the uptake of SA was chemically exothermic in nature between 15 and 80°C. In addition, the spent SAPAMAA could be regenerated by the removal of adsorbed SA with NaOH and ethanol to regain the original SAPAMAA, the regenerated SAPAMAA also exhibited the high adsorption capacity after 10 runs. Moreover, SAPAMAA could also be applied to uptake SA from a real water (Anzali lagoon water). We envisage that the prepared nano-dendritic with remarkable characteristics such as environmentally friendly, low-cost, easy preparation in large quantity, high mechanical and chemical stability

Development Trends in Porous Adsorbents for Carbon Capture.

PubMed

Sreenivasulu, Bolisetty; Sreedhar, Inkollu; Suresh, Pathi; Raghavan, Kondapuram Vijaya

2015-11-03

Accumulation of greenhouse gases especially CO2 in the atmosphere leading to global warming with undesirable climate changes has been a serious global concern. Major power generation in the world is from coal based power plants. Carbon capture through pre- and post- combustion technologies with various technical options like adsorption, absorption, membrane separations, and chemical looping combustion with and without oxygen uncoupling have received considerable attention of researchers, environmentalists and the stake holders. Carbon capture from flue gases can be achieved with micro and meso porous adsorbents. This review covers carbonaceous (organic and metal organic frameworks) and noncarbonaceous (inorganic) porous adsorbents for CO2 adsorption at different process conditions and pore sizes. Focus is also given to noncarbonaceous micro and meso porous adsorbents in chemical looping combustion involving insitu CO2 capture at high temperature (>400 °C). Adsorption mechanisms, material characteristics, and synthesis methods are discussed. Attention is given to isosteric heats and characterization techniques. The options to enhance the techno-economic viability of carbon capture techniques by integrating with CO2 utilization to produce industrially important chemicals like ammonia and urea are analyzed. From the reader's perspective, for different classes of materials, each section has been summarized in the form of tables or figures to get a quick glance of the developments.

In vitro and in vivo evaluation of ordered mesoporous silica as a novel adsorbent in liquisolid formulation

PubMed Central

Chen, Bao; Wang, Zhouhua; Quan, Guilan; Peng, Xinsheng; Pan, Xin; Wang, Rongchang; Xu, Yuehong; Li, Ge; Wu, Chuanbin

2012-01-01

Background A liquisolid technique has been reported to be a new approach to improve the release of poorly water-soluble drugs for oral administration. However, an apparent limitation of this technique is the formulation of a high dose because a large amount of liquid vehicle is needed, which finally results in a low-dose liquisolid formulation. Silica as an absorbent has been used extensively in liquisolid formulations. Although nanoparticle silica can be prepared and used to improve liquid adsorption capacity, loading a high dose of drug into a liquisolid is still a challenge. With the aim of improving adsorption capacity and accordingly achieving high drug loading, ordered mesoporous silica with a high surface area and narrow pore size distribution was synthesized and used in a liquisolid formulation. Methods Ordered mesoporous silica was synthesized and its particle size and morphology were tailored by controlling the concentration of cetyltrimethyl ammonium bromide. The ordered mesoporous silica synthesized was characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, small-angle x-ray diffraction, wide angle x-ray diffraction, and nitrogen adsorption-desorption measurements. The liquid adsorption capacity of ordered mesoporous silica was subsequently compared with that of conventional silica materials using PEG400 as the model liquid. Carbamazepine was chosen as a model drug to prepare the liquisolid formulation, with ordered mesoporous silica as the adsorbent material. The preparation was evaluated and compared with commercially available fast-release carbamazepine tablets in vitro and in vivo. Results Characterization of the ordered mesoporous silica synthesized in this study indicated a huge Brunauer–Emmett–Teller surface area (1030 m2/g), an ordered mesoporous structure with a pore size of 2.8 nm, and high adsorption capacity for liquid compared with conventional silica. Compared with fast

Towards understanding KOH conditioning of amidoxime-based polymer adsorbents for sequestering uranium from seawater

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

Pan, Horng-Bin; Kuo, Li-Jung; Wood, Jordana

2015-01-01

Conditioning of polymer fiber adsorbents grafted with amidoxime and carboxylic acid groups is necessary to make the materials hydrophilic for sequestering uranium from seawater. Spectroscopic techniques were employed to study the effectiveness of the traditional KOH conditioning method (2.5% KOH at 80 oC) on recently developed high-surface-area amidoxime-based polymer fiber adsorbents developed at Oak Ridge National Laboratory. FTIR spectra reveal that the KOH conditioning process removes the proton from the carboxylic acids and also converts the amidoxime groups to carboxylate groups in the adsorbent. With prolonged KOH treatment (>1 hr) at 80 oC, physical damage to the adsorbent material occursmore » which can lead to a significant reduction in the adsorbent’s uranium adsorption capability in real seawater during extended exposure times (>21 days). The physical damage to the adsorbent can be minimized by lowering KOH conditioning temperature. For the high-surface-area amidoxime-based adsorbents, 20 min of conditioning in 2.5% KOH at 80 oC or 1 hr of conditioning in 2.5% KOH at 60 oC appears sufficient to achieve de-protonation of the carboxylic acid with minimal harmful effects to the adsorbent material. The use of NaOH instead of KOH can also reduce the cost of the base treatment process required for conditioning the amidoxime-based sorbents with minimal loss of adsorption capacity (≤ 7%).« less

Development of chemically activated N-enriched carbon adsorbents from urea-formaldehyde resin for CO2 adsorption: Kinetics, isotherm, and thermodynamics.

PubMed

Tiwari, Deepak; Bhunia, Haripada; Bajpai, Pramod K

2018-07-15

Nitrogen enriched carbon adsorbents with high surface areas were successfully prepared by carbonizing the low-cost urea formaldehyde resin, followed by KOH activation. Different characterization techniques were used to determine the structure and surface functional groups. Maximum surface area and total pore volume of 4547 m 2  g -1 and 4.50 cm 3  g -1 were found by controlling activation conditions. The optimized sample denoted as UFA-3-973 possesses a remarkable surface area, which is found to be one of the best surface areas achieved so far. Nitrogen content of this sample was found to be 22.32%. Dynamic CO 2 uptake capacity of the carbon adsorbents were determined thermogravimetrically at different CO 2 concentrations (6-100%) and adsorption temperatures (303-373 K) which have a much more relevance for the flue gas application. Highest adsorption capacity of 2.43 mmol g -1 for this sample was obtained at 303 K under pure CO 2 flow. Complete regenerability of the adsorbent over four adsorption-desorption cycles was obtained. Fractional order kinetic model provided best description of adsorption over all adsorption temperatures and CO 2 concentrations. Heterogeneity of the adsorbent surface was confirmed from the Langmuir and Freundlich isotherms fits and isosteric heat of adsorption values. Exothermic, spontaneous and feasible nature of adsorption process was confirmed from thermodynamic parameter values. The combination of high surface area and large pore volume makes the adsorbent a new promising carbon material for CO 2 capture from power plant flue gas and for other relevant applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

A machine learning approach to graph-theoretical cluster expansions of the energy of adsorbate layers

NASA Astrophysics Data System (ADS)

Vignola, Emanuele; Steinmann, Stephan N.; Vandegehuchte, Bart D.; Curulla, Daniel; Stamatakis, Michail; Sautet, Philippe

2017-08-01

The accurate description of the energy of adsorbate layers is crucial for the understanding of chemistry at interfaces. For heterogeneous catalysis, not only the interaction of the adsorbate with the surface but also the adsorbate-adsorbate lateral interactions significantly affect the activation energies of reactions. Modeling the interactions of the adsorbates with the catalyst surface and with each other can be efficiently achieved in the cluster expansion Hamiltonian formalism, which has recently been implemented in a graph-theoretical kinetic Monte Carlo (kMC) scheme to describe multi-dentate species. Automating the development of the cluster expansion Hamiltonians for catalytic systems is challenging and requires the mapping of adsorbate configurations for extended adsorbates onto a graphical lattice. The current work adopts machine learning methods to reach this goal. Clusters are automatically detected based on formalized, but intuitive chemical concepts. The corresponding energy coefficients for the cluster expansion are calculated by an inversion scheme. The potential of this method is demonstrated for the example of ethylene adsorption on Pd(111), for which we propose several expansions, depending on the graphical lattice. It turns out that for this system, the best description is obtained as a combination of single molecule patterns and a few coupling terms accounting for lateral interactions.

Fiber-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

DOEpatents

Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

2016-09-06

A fiber-based adsorbent and a related method of manufacture are provided. The fiber-based adsorbent includes polymer fibers with grafted side chains and an increased surface area per unit weight over known fibers to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. The polymer fibers include a circular morphology in some embodiments, having a mean diameter of less than 15 microns, optionally less than about 1 micron. In other embodiments, the polymer fibers include a non-circular morphology, optionally defining multiple gear-shaped, winged-shaped or lobe-shaped projections along the length of the polymer fibers. A method for forming the fiber-based adsorbents includes irradiating high surface area polymer fibers, grafting with polymerizable reactive monomers, reacting the grafted fibers with hydroxylamine, and conditioning with an alkaline solution. High surface area fiber-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

Fiber-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

DOEpatents

Janke, Christopher J; Dai, Sheng; Oyola, Yatsandra

2014-05-13

A fiber-based adsorbent and a related method of manufacture are provided. The fiber-based adsorbent includes polymer fibers with grafted side chains and an increased surface area per unit weight over known fibers to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. The polymer fibers include a circular morphology in some embodiments, having a mean diameter of less than 15 microns, optionally less than about 1 micron. In other embodiments, the polymer fibers include a non-circular morphology, optionally defining multiple gear-shaped, winged-shaped or lobe-shaped projections along the length of the polymer fibers. A method for forming the fiber-based adsorbents includes irradiating high surface area polymer fibers, grafting with polymerizable reactive monomers, reacting the grafted fibers with hydroxylamine, and conditioning with an alkaline solution. High surface area fiber-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

Tunable magnetism in metal adsorbed fluorinated nanoporous graphene

DOE PAGES

Kumar, Pankaj; Sharma, Vinit; Reboredo, Fernando A.; ...

2016-08-24

Developing nanostructures with tunable magnetic states is crucial for designing novel data storage and quantum information devices. Using density functional theory, we study the thermodynamic stability and magnetic properties of tungsten adsorbed tri-vacancy fluorinated (TVF) graphene. We demonstrate a strong structure-property relationship and its response to external stimuli via defect engineering in graphene-based materials. Complex interplay between defect states and the chemisorbed atom results in a large magnetic moment of 7 μ B along with high in-plane magneto-crystalline anisotropy energy (MAE) of 17 meV. Under the influence of electric field, spin crossover effect accompanied by a change in the MAEmore » is observed. The ascribed change in spin-configuration is caused by the modification of exchange coupling between defect states and a change in the occupation of d-orbitals of the metal complex. In conclusion, our predictions open a promising way towards controlling the magnetic properties in graphene based spintronic and non-volatile memory devices.« less

Enhanced removal of nitrate from water using surface modification of adsorbents--a review.

PubMed

Loganathan, Paripurnanda; Vigneswaran, Saravanamuthu; Kandasamy, Jaya

2013-12-15

Elevated concentration of nitrate results in eutrophication of natural water bodies affecting the aquatic environment and reduces the quality of drinking water. This in turn causes harm to people's health, especially that of infants and livestock. Adsorbents with the high capacity to selectively adsorb nitrate are required to effectively remove nitrate from water. Surface modifications of adsorbents have been reported to enhance their adsorption of nitrate. The major techniques of surface modification are: protonation, impregnation of metals and metal oxides, grafting of amine groups, organic compounds including surfactant coating of aluminosilicate minerals, and heat treatment. This paper reviews current information on these techniques, compares the enhanced nitrate adsorption capacities achieved by the modifications, and the mechanisms of adsorption, and presents advantages and drawbacks of the techniques. Most studies on this subject have been conducted in batch experiments. These studies need to include continuous mode column trials which have more relevance to real operating systems and pilot-plant trials. Reusability of adsorbents is important for economic reasons and practical treatment applications. However, only limited information is available on the regeneration of surface modified adsorbents. Copyright © 2013 Elsevier Ltd. All rights reserved.

Preparation and Evaluation of Adsorbents from Coal and Irvingia gabonensis Seed Shell

NASA Astrophysics Data System (ADS)

Ezeokonkwo, Mercy A.; Ofor, Okechukwu F.; Ani, Julius U.

2017-12-01

The adsorption of Cd(II) and Pb(II) ions on adsorbents prepared from sub-bituminous coal, lignite and a blend of coal and Irvingia gabonensis seed shells was investigated. Fourier transform infrared, scanning electron microscope and X-ray fluorescence analyses implicated hydroxyl, carbonyl, Al2O3 and SiO2 as being responsible for binding the metal ions on the porous adsorbents. The optimum adsorption of carbonized lignite for the removal of Cd(II) and Pb(II) ions from aqueous media were 80.93% and 87.85%, respectively. Batch adsorption was done by effect of adsorbent dosage, pH, contact time, temperature, particle size, and initial concentration. Equilibrium for the removal of Pb(II) and Cd(II) was established within 100 and 120 min respectively. Blending the lignite-derived adsorbent with Irvingia gabonensis seed shell improved the performance significantly. More improvement was observed on modification of the blend using NaOH and H3PO4. Pb(II) was preferentially adsorbed than Cd(II) in all cases. Adsorption of Cd(II) and Pb(II) ions followed Langmuir isotherm. The kinetics of adsorption was best described by pseudo-second order model. The potential for using a blend of coal and agricultural byproduct (Irvingia gabonensis seed shell) was found to be a viable alternative for removal of toxic heavy metals from aqueous solutions.

Development of a cost-effective CO2 adsorbent from petroleum coke via KOH activation

NASA Astrophysics Data System (ADS)

Jang, Eunji; Choi, Seung Wan; Hong, Seok-Min; Shin, Sangcheol; Lee, Ki Bong

2018-01-01

The capture of CO2 via adsorption is considered an effective technology for decreasing global warming issues; hence, adsorbents for CO2 capture have been actively developed. Taking into account cost-effectiveness and environmental concerns, the development of CO2 adsorbents from waste materials is attracting considerable attention. In this study, petroleum coke (PC), which is the carbon residue remaining after heavy oil upgrading, was used to produce high-value-added porous carbon for CO2 capture. Porous carbon materials were prepared by KOH activation using different weight ratios of KOH/PC (1:1, 2:1, 3:1, and 4:1) and activation temperatures (600, 700, and 800 °C). The specific surface area and total pore volume of resulting porous carbon materials increased with KOH amount, reaching up to 2433 m2/g and 1.11 cm3/g, respectively. The sample prepared under moderate conditions with a KOH/PC weight ratio of 2:1 and activation temperature of 700 °C exhibited the highest CO2 adsorption uptake of 3.68 mmol/g at 25 °C and 1 bar. Interestingly, CO2 adsorption uptake was linearly correlated with the volume of micropores less than 0.8 nm, indicating that narrow micropore volume is crucial for CO2 adsorption. The prepared porous carbon materials also exhibited good selectivity for CO2 over N2, rapid adsorption, facile regeneration, and stable adsorption-desorption cyclic performance, demonstrating potential as a candidate for CO2 capture.

Extraction of triazole fungicides in environmental waters utilizing poly (ionic liquid)-functionalized magnetic adsorbent.

PubMed

Liu, Cheng; Liao, Yingmin; Huang, Xiaojia

2017-11-17

This work prepared a new poly (ionic liquid)-functionalized magnetic adsorbent (PFMA) for the extraction of triazole fungicides (TFs) in environmental waters prior to determination by high performance liquid chromatography/diode array detection (HPLC-DAD). A polymerizable ionic liquid, 1-methyl-3-allylimidazolium bis(trifluoromethylsulfonyl)imide was employed to copolymerize with divinylbenzene on the surface of modified magnetite to fabricate the PFMA. The morphology, spectroscopic and magnetic properties of the new adsorbent were investigated by different techniques. A series of key parameters that influence the extraction performance including the amount of PFMA, desorption solvent, adsorption and desorption time, sample pH value and ionic strength were optimized in detail. Under the optimum conditions, the prepared PFMA could extract targeted TFs effectively and quickly under the format of magnetic solid-phase extraction (MSPE). Satisfactory linearities were achieved in the range of 0.1-200.0μg/L for triadimenol and 0.05-200.0μg/L for other TFs with good coefficients of determination above 0.99 for all analytes. The limits of detection (S/N=3) and limits of quantification (S/N=10) for TFs were in the range of 0.0050-0.0078μg/L and 0.017-0.026μg/L, respectively. Environmental waters including lake, river and well waters were used to demonstrate the applicability of developed MSPE-HPLC-DAD method, and satisfactory recoveries and repeatability were obtained. Copyright © 2017 Elsevier B.V. All rights reserved.

Highly selective removal of Zn(II) ion from hot-dip galvanizing pickling waste with amino-functionalized Fe3O4@SiO2 magnetic nano-adsorbent.

PubMed

Bao, Shuangyou; Tang, Lihong; Li, Kai; Ning, Ping; Peng, Jinhui; Guo, Huibin; Zhu, Tingting; Liu, Ye

2016-01-15

Amino-functionalized Fe3O4@SiO2 magnetic nano-adsorbent was used as a novel sorbent to highly selective removal of Zn(II) ion from hot-dip galvanizing pickling waste in the presence of Fe(II). These hot-dip galvanizing pickling waste mainly contain ZnCl2 and FeCl2 in aqueous HCl media. The properties of this magnetic adsorbent were examined by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), infrared spectrometer (FT-IR) and BET surface area measurements. Various factors influencing the adsorption of Zn(II) ion such as initial concentration of metal ions, the amount of adsorbent, pH value of the solutions, the concentration of coexisting iron ion were investigated by batch experiments. The results indicated that the adsorption equilibrium data obeyed the Freundlich model with maximum adsorption capacities for Zn(II) to 169.5mg/g. The maximum adsorption occurred at pH 5±0.1 and Fe(II) interferences had no obvious influence. This work provides a potential and unique technique for zinc ion removal from hot-dip galvanizing pickling waste. Copyright © 2015 Elsevier Inc. All rights reserved.

Effect of gas adsorption on acoustic wave propagation in MFI zeolite membrane materials: experiment and molecular simulation.

PubMed

Manga, Etoungh D; Blasco, Hugues; Da-Costa, Philippe; Drobek, Martin; Ayral, André; Le Clezio, Emmanuel; Despaux, Gilles; Coasne, Benoit; Julbe, Anne

2014-09-02

The present study reports on the development of a characterization method of porous membrane materials which consists of considering their acoustic properties upon gas adsorption. Using acoustic microscopy experiments and atomistic molecular simulations for helium adsorbed in a silicalite-1 zeolite membrane layer, we showed that acoustic wave propagation could be used, in principle, for controlling the membranes operando. Molecular simulations, which were found to fit experimental data, showed that the compressional modulus of the composite system consisting of silicalite-1 with adsorbed He increases linearly with the He adsorbed amount while its shear modulus remains constant in a large range of applied pressures. These results suggest that the longitudinal and Rayleigh wave velocities (VL and VR) depend on the He adsorbed amount whereas the transverse wave velocity VT remains constant.

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.

Bromocriptine tablet of self-microemulsifying system adsorbed onto porous carrier to stimulate lipoproteins secretion for brain cellular uptake.

PubMed

Thongrangsalit, Sirigul; Phaechamud, Thawatchai; Lipipun, Vimolmas; Ritthidej, Garnpimol C

2015-07-01

Both low solubility and high hepatic metabolism cause low oral bioavailability of bromocriptine mesylate (BM) leading to very low drug amount in brain. Self-microemulsion (SME) tablets were developed to improve solubility, stimulate lipoprotein synthesis to promote lymphatic transport, avoid hepatic metabolism and target drug to brain. SME liquid containing castor oil, Tween(®) 80 and Cremophor(®) EL was prepared and then adsorbed onto solid carries, Aerosil(®)200, Aeroperl(®)300 or NeusilinUS2(®), yielding SME powders. The optimal ratios of SME liquid to carriers determined from flowability and scanning electron photomicrographs before tableting were 1.5:1, 2:1 and 2.5:1 for Aerosil(®)200, Aeroperl(®)300 and NeusilinUS2(®), respectively. Only Aeroperl(®)300 SME tablet had comparable dissolution to BM commercial tablet. From in vitro study in Caco-2 cells, fluorescein loaded SME tablet showed higher uptake than fluorescein loaded in either oil or surfactant. Although significantly lower amount of drug was permeated from SME tablet than from commercial tablet, higher drug uptake was obviously observed (P<0.05). In addition, higher lipoprotein synthesis expressing as content of apolipoprotein B (apo-B) found in secreted chylomicron resulted in higher drug uptake in co-culture of brain endothelial cells (bEnd.3) and astrocytes (CTX TNA2) from drug loaded SME tablet when compared to commercial tablet (P<0.05) due to binding of apo-B to LDL receptors expressed on the surface of endothelial cells. Therefore, tablet of SME adsorbed onto porous carrier potentially delivered BM to brain via lymphatic transport by increasing the lipoprotein synthesis. Copyright © 2015. Published by Elsevier B.V.

Lake Water Quality Improvement by Using Waste Mussel Shell Powder as an Adsorbent

NASA Astrophysics Data System (ADS)

Zukri, N. I.; Khamidun, M. H.; Sapiren, M. S.; Abdullah, S.; Rahman, M. A. A.

2018-04-01

Lake water in UTHM was slightly greenish in color indicating the eutrophication process. Eutrophication problem is due to excessive amount of nutrient in the lake water which causes nuisance growth of algae and other aquatic plant. The improvement of lake water quality should be conducted wisely in preventing from eutrophication problem by using a suitable water treatment method. Natural materials, agricultural wastes and industrial wastes are locally available sources can be utilized as low-cost adsorbents. The natural abundant source of waste mussel’s shells is advantages to use as basis material to produce the low cost adsorbent for water treatment. Batch experiments were carried out with the preparation 500 ml volume of lake water sample with the dosage of 2.5g, 7.5g and 12.5g. Then the solution shaking in an incubator with 200 rpm shaking speed. The various dosage of mussel shell greatly affected pollutants removal. Both of NH4+ and PO43- have a higher percentage removal with 31.28% and 21.74% at the 7.5g of sample dosage. Other parameters such as COD and TSS also shown good percentage of removal at 7.5g of dosage sample with 44.45% and 25% respectively. While, dosage at 2.5g was performed as a good adsorption capacity of NH4+, PO43-, COD and TSS as high as 0.142, 0.234, 7.6 and 20 mg/g, respectively. These experimental results suggested that the use of mussel shell powder as good basis material in removing pollutants from lake water.

Evaluation of Aluminium Dross as Adsorbent for Removal of Carcinogenic Congo Red Dye in Wastewater

NASA Astrophysics Data System (ADS)

Zakaria, Mohamad Zulfika Hazielim b.; Zauzi, Nur Syuhada Ahmad; Baini, Rubiyah; Sutan, Norsuzailina Mohamed; Rezaur Rahman, Md

2017-06-01

In this study, aluminium dross waste generated from aluminium smelting industries was employed as adsorbent in removing of congo red dye in aqueous solution. The raw aluminium dross as adsorbent was characterized using Scanning Electron Microscope (SEM), Brunauer-Emmett-Teller (BET) for surface area and X-Ray Fluorescence (XRF) Spectroscopy. Adsorption experiments were carried out by batch system at different adsorbent mass, pH, and initial dye concentration. The results showed that the per cent removal of dye increased as adsorbent mass increased. It was found that 0.4 gram of adsorbent can remove approximately 100 % of dye at pH 9 for dye concentration 20 and 40 ppm. Therefore, it can be concluded that raw aluminium dross without undergone any treatment can be effectively used for the adsorption of congo red in textile wastewater related industries.

Selective cesium removal from radioactive liquid waste by crown ether immobilized new class conjugate adsorbent.

PubMed

Awual, Md Rabiul; Yaita, Tsuyoshi; Taguchi, Tomitsugu; Shiwaku, Hideaki; Suzuki, Shinichi; Okamoto, Yoshihiro

2014-08-15

Conjugate materials can provide chemical functionality, enabling an assembly of the ligand complexation ability to metal ions that are important for applications, such as separation and removal devices. In this study, we developed ligand immobilized conjugate adsorbent for selective cesium (Cs) removal from wastewater. The adsorbent was synthesized by direct immobilization of dibenzo-24-crown-8 ether onto inorganic mesoporous silica. The effective parameters such as solution pH, contact time, initial Cs concentration and ionic strength of Na and K ion concentrations were evaluated and optimized systematically. This adsorbent was exhibited the high surface area-to-volume ratios and uniformly shaped pores in case cavities, and its active sites kept open functionality to taking up Cs. The obtained results revealed that adsorbent had higher selectivity toward Cs even in the presence of a high concentration of Na and K and this is probably due to the Cs-π interaction of the benzene ring. The proposed adsorbent was successfully applied for radioactive Cs removal to be used as the potential candidate in Fukushima nuclear wastewater treatment. The adsorbed Cs was eluted with suitable eluent and simultaneously regenerated into the initial form for the next removal operation after rinsing with water. The adsorbent retained functionality despite several cycles during sorption-elution-regeneration operations. Copyright © 2014 Elsevier B.V. All rights reserved.

Double-Layer Structured CO2 Adsorbent Functionalized with Modified Polyethyleneimine for High Physical and Chemical Stability.

PubMed

Jeon, Sunbin; Jung, Hyunchul; Kim, Sung Hyun; Lee, Ki Bong

2018-06-18

CO 2 capture using polyethyleneimine (PEI)-impregnated silica adsorbents has been receiving a lot of attention. However, the absence of physical stability (evaporation and leaching of amine) and chemical stability (urea formation) of the PEI-impregnated silica adsorbent has been generally established. Therefore, in this study, a double-layer impregnated structure, developed using modified PEI, is newly proposed to enhance the physical and chemical stabilities of the adsorbent. Epoxy-modified PEI and diepoxide-cross-linked PEI were impregnated via a dry impregnation method in the first and second layers, respectively. The physical stability of the double-layer structured adsorbent was noticeably enhanced when compared to the conventional adsorbents with a single layer. In addition to the enhanced physical stability, the result of simulated temperature swing adsorption cycles revealed that the double-layer structured adsorbent presented a high potential working capacity (3.5 mmol/g) and less urea formation under CO 2 -rich regeneration conditions. The enhanced physical and chemical stabilities as well as the high CO 2 working capacity of the double-layer structured adsorbent were mainly attributed to the second layer consisting of diepoxide-cross-linked PEI.

Affinity binding of antibodies to supermacroporous cryogel adsorbents with immobilized protein A for removal of anthrax toxin protective antigen.

PubMed

Ingavle, Ganesh C; Baillie, Les W J; Zheng, Yishan; Lis, Elzbieta K; Savina, Irina N; Howell, Carol A; Mikhalovsky, Sergey V; Sandeman, Susan R

2015-05-01

Polymeric cryogels are efficient carriers for the immobilization of biomolecules because of their unique macroporous structure, permeability, mechanical stability and different surface chemical functionalities. The aim of the study was to demonstrate the potential use of macroporous monolithic cryogels for biotoxin removal using anthrax toxin protective antigen (PA), the central cell-binding component of the anthrax exotoxins, and covalent immobilization of monoclonal antibodies. The affinity ligand (protein A) was chemically coupled to the reactive hydroxyl and epoxy-derivatized monolithic cryogels and the binding efficiencies of protein A, monoclonal antibodies to the cryogel column were determined. Our results show differences in the binding capacity of protein A as well as monoclonal antibodies to the cryogel adsorbents caused by ligand concentrations, physical properties and morphology of surface matrices. The cytotoxicity potential of the cryogels was determined by an in vitro viability assay using V79 lung fibroblast as a model cell and the results reveal that the cryogels are non-cytotoxic. Finally, the adsorptive capacities of PA from phosphate buffered saline (PBS) were evaluated towards a non-glycosylated, plant-derived human monoclonal antibody (PANG) and a glycosylated human monoclonal antibody (Valortim(®)), both of which were covalently attached via protein A immobilization. Optimal binding capacities of 108 and 117 mg/g of antibody to the adsorbent were observed for PANG attached poly(acrylamide-allyl glycidyl ether) [poly(AAm-AGE)] and Valortim(®) attached poly(AAm-AGE) cryogels, respectively, This indicated that glycosylation status of Valortim(®) antibody could significantly increase (8%) its binding capacity relative to the PANG antibody on poly(AAm-AGE)-protien-A column (p < 0.05). The amounts of PA which remained in the solution after passing PA spiked PBS through PANG or Valortim bound poly(AAm-AGE) cryogel were significantly (p < 0

Adsorbed water and thin liquid films on Mars

NASA Astrophysics Data System (ADS)

Boxe, C. S.; Hand, K. P.; Nealson, K. H.; Yung, Y. L.; Yen, A. S.; Saiz-Lopez, A.

2012-07-01

At present, bulk liquid water on the surface and near-subsurface of Mars does not exist due to the scarcity of condensed- and gas-phase water, pressure and temperature constraints. Given that the nuclei of soil and ice, that is, the soil solid and ice lattice, respectively, are coated with adsorbed and/or thin liquid films of water well below 273 K and the availability of water limits biological activity, we quantify lower and upper limits for the thickness of such adsorbed/water films on the surface of the Martian regolith and for subsurface ice. These limits were calculated based on experimental and theoretical data for pure water ice and water ice containing impurities, where water ice containing impurities exhibit thin liquid film enhancements, ranging from 3 to 90. Close to the cold limit of water stability (i.e. 273 K), thin liquid film thicknesses at the surface of the Martian regolith is 0.06 nm (pure water ice) and ranges from 0.2 to 5 nm (water ice with impurities). An adsorbed water layer of 0.06 nm implies a dessicated surface as the thickness of one monolayer of water is 0.3 nm but represents 0.001-0.02% of the Martian atmospheric water vapour inventory. Taking into account the specific surface area (SSA) of surface-soil (i.e. top 1 mm of regolith and 0.06 nm adsorbed water layer), shows Martian surface-soil may contain interfacial water that represents 6-66% of the upper- and lower-limit atmospheric water vapour inventory and almost four times and 33%, the lower- and upper-limit Martian atmospheric water vapour inventory. Similarly, taking the SSA of Martian soil, the top 1 mm or regolith at 5 nm thin liquid water thickness, yields 1.10×1013 and 6.50×1013 litres of waters, respectively, 55-325 times larger than Mars' atmospheric water vapour inventory. Film thicknesses of 0.2 and 5 nm represent 2.3×104-1.5×106 litres of water, which is 6.0×10-7-4.0×10-4%, respectively, of a 10 pr μm water vapour column, and 3.0×10-6-4.0×10-4% and 6.0×10

Alternative alkaline conditioning of amidoxime based adsorbent for uranium extraction from seawater

DOE PAGES

Das, Sadananda; Liao, Wei -Po; Byers, Maggie Flicker; ...

2015-10-18

Alkaline conditioning of the amidoxime based adsorbents is a significant step in the preparation of the adsorbent for uranium uptake from seawater. The effects of various alkaline conditioning parameters such as the type of alkaline reagent, reaction temperature, and reaction time were investigated with respect to uranium adsorption capacity from simulated seawater (spiked with 8 ppm uranium) and natural seawater (from Sequim Bay, WA). An adsorbent (AF1) was prepared at the Oak Ridge National Laboratory by radiation-induced graft polymerization (RIGP) with acrylonitrile and itaconic acid onto high-surface-area polyethylene fibers. For the AF1 adsorbent, sodium hydroxide emerged as a better reagentmore » for alkaline conditioning over potassium hydroxide, which has typically been used in previous studies, because of higher uranium uptake capacity and lower cost over the other candidate alkaline reagents investigated in this study. Furthermore, the use of sodium hydroxide in place of potassium hydroxide is shown to result in a 21–30% decrease in the cost of uranium recovery.« less

Alternative alkaline conditioning of amidoxime based adsorbent for uranium extraction from seawater

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

Das, Sadananda; Liao, Wei -Po; Byers, Maggie Flicker

Alkaline conditioning of the amidoxime based adsorbents is a significant step in the preparation of the adsorbent for uranium uptake from seawater. The effects of various alkaline conditioning parameters such as the type of alkaline reagent, reaction temperature, and reaction time were investigated with respect to uranium adsorption capacity from simulated seawater (spiked with 8 ppm uranium) and natural seawater (from Sequim Bay, WA). An adsorbent (AF1) was prepared at the Oak Ridge National Laboratory by radiation-induced graft polymerization (RIGP) with acrylonitrile and itaconic acid onto high-surface-area polyethylene fibers. For the AF1 adsorbent, sodium hydroxide emerged as a better reagentmore » for alkaline conditioning over potassium hydroxide, which has typically been used in previous studies, because of higher uranium uptake capacity and lower cost over the other candidate alkaline reagents investigated in this study. Furthermore, the use of sodium hydroxide in place of potassium hydroxide is shown to result in a 21–30% decrease in the cost of uranium recovery.« less

Improved of Natural Gas Storage with Adsorbed Natural Gas (ANG) Technology Using Activated Carbon from Plastic Waste Polyethylene Terepthalate

NASA Astrophysics Data System (ADS)

Yuliusman; Nasruddin; Sanal, A.; Bernama, A.; Haris, F.; Hardhi, M.

2017-07-01

Indonesia imports high amount of Fuel Oil. Although Indonesia has abundant amount of natural gas reserve, the obstacle lies within the process of natural gas storage itself. In order to create a safe repository, the ANG (Adsorbed Natural Gas) technology is planned. ANG technology in itself has been researched much to manufacture PET-based activated carbon for natural gas storage, but ANG still has several drawbacks. This study begins with making preparations for the equipment and materials that will be used, by characterizing the natural gas, measuring the empty volume, and degassing. The next step will be to examine the adsorption process. The maximum storage capacity obtained in this study for a temperature of 27°C and pressure of 35 bar is 0.0586 kg/kg, while for the desorption process, a maximum value for desorption efficiency was obtained on 35°C temperature with a value of 73.39%.

Modifying protein adsorption by layers of glutathione pre-adsorbed on Au(111)

NASA Astrophysics Data System (ADS)

Vallée, Anne; Humblot, Vincent; Méthivier, Christophe; Dumas, Paul; Pradier, Claire-Marie

2011-12-01

Molecular interaction with metal surfaces raises fundamental questions regarding their binding tendency, their dispersion on the surface, as well as their conformation which may change their biological properties; addressing these questions, and being able to tune protein interactions, is of primary importance for the control of biointerfaces. In this study, one tripeptide, GSH (glu-cys-gly), was used to condition gold surfaces and thus influence the adsorption of bovine serum albumin (BSA). Depending on the pH value of the GSH solution, cationic, zwitterionic or anionic forms of the tripeptide could be stabilised on the surface, before interacting with BSA solutions. The amount of proteins was observed to depend both on the chemical state of the adsorbed underlying peptide and on the solvent of the protein solution, indicating an important role of electrostatic interactions upon protein adsorption. Moreover, atomic force microscopy (AFM), and synchrotron IR microscopy revealed a heterogeneous distribution of proteins on the GSH layer.

Shock compression and flash-heating of molecular adsorbates on the picosecond time scale

NASA Astrophysics Data System (ADS)

Berg, Christopher Michael

An ultrafast nonlinear coherent laser spectroscopy termed broadband multiplex vibrational sum-frequency generation (SFG) with nonresonant suppression was employed to monitor vibrational transitions of molecular adsorbates on metallic substrates during laser-driven shock compression and flash-heating. Adsorbates were in the form of well-ordered self-assembled monolayers (SAMs) and included molecular explosive simulants, such as nitroaromatics, and long chain-length alkanethiols. Based on reflectance measurements of the metallic substrates, femtosecond flash-heating pulses were capable of producing large-amplitude temperature jumps with DeltaT = 500 K. Laser-driven shock compression of SAMs produced pressures up to 2 GPa, where 1 GPa ≈ 1 x 104 atm. Shock pressures were estimated via comparison with frequency shifts observed in the monolayer vibrational transitions during hydrostatic pressure measurements in a SiC anvil cell. Molecular dynamics during flash-heating and shock loading were probed with vibrational SFG spectroscopy with picosecond temporal resolution and sub-nanometer spatial resolution. Flash-heating studies of 4-nitrobenzenethiolate (NBT) on Au provided insight into effects from hot-electron excitation of the molecular adsorbates at early pump-probe delay times. At longer delay times, effects from the excitation of SAM lattice modes and lower-energy NBT vibrations were shown. In addition, flash-heating studies of alkanethiolates demonstrated chain disordering behaviors as well as interface thermal conductances across the Au-SAM junction, which was of specific interest within the context of molecular electronics. Shock compression studies of molecular explosive simulants, such as 4-nitrobenzoate (NBA), demonstrated the proficiency of this technique to observe shock-induced molecular dynamics, in this case orientational dynamics, on the picosecond time scale. Results validated the utilization of these refined shock loading techniques to probe the shock

Graphene oxide: an adsorbent for the extraction and quantification of aflatoxins in peanuts by high-performance liquid chromatography.

PubMed

Yu, Li; Li, Peiwu; Zhang, Qi; Zhang, Wen; Ding, Xiaoxia; Wang, Xiupin

2013-11-29

In this paper, graphene oxide (GO) was synthesized and specifically selected by centrifugation to extract four aflatoxins (B1, B2, G1, and G2) as an effective adsorbent. Then, the amount of aflatoxins was quantitatively measured by high-performance liquid chromatography (HPLC). The GO was characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), and ultraviolet (UV) spectrophotometer. Several parameters that could affect the extraction efficiency, including the GO amount, methanol concentration in the extraction solvent, spiked amount, extraction time, and elution cycle, were also investigated and optimized in this work. Under optimal conditions, good linear relationships were achieved with the correlation coefficient (r) ranging from 0.99217 to 0.99995. The detection limit of this method for the four aflatoxins ranged from 0.08 to 0.65ng/g. Finally, the proposed method has been successfully applied to determine aflatoxins in peanut samples. The results show that the recoveries of the four aflatoxins range from 85.1% to 100.8% with the relative standard deviations between 2.1% and 7.9%. Copyright © 2013 Elsevier B.V. All rights reserved.

Static and hydrodynamic studies of the conformation of adsorbed macromolecules at the solid/liquid interface

NASA Astrophysics Data System (ADS)

Yavorsky, D. P.

1981-08-01

The structure of an adsorbed macromolecular layer at the solid/liquid interface under both stationary and flow conditions is examined. The conformation of adsorbed bovine serum albumin (BSA) is deduced from the thickness of surface layers formed on the pore walls of track etched (mica) membranes. Changes in membrane permeability due to protein adsorption are related directly to a net reduction in pore size or an equivalent adsorbed layer thickness. Complementary permeability measurements using electrolyte conduction, tracer diffusion, and pressure driven flow have verified the unique structural qualities of the track etched membrane and collectively demonstrate an ability to determine bare pore size with an accuracy of + or - 2A. The average static thickness of an adsorbed BSA layer, as derived from electrolyte conduction and tracer diffusion, was 43 + or - 3A independent of pore size. In comparison with the known BSA solution dimensions, this measured thickness is consistent with a monolayer of structurally unperturbed protein molecules each oriented in a "side-on" position. Pronounced conformational changes in adsorbed BSA layers were observed under conditions of shear flow. Electrostatic interactions were also shown to significantly affect adsorbed protein conformation through changes in solution ionic strength and surface charge.

Enhanced encapsulation of metoprolol tartrate with carbon nanotubes as adsorbent

NASA Astrophysics Data System (ADS)

Garala, Kevin; Patel, Jaydeep; Patel, Anjali; Dharamsi, Abhay

2011-12-01

A highly water-soluble antihypertensive drug, metoprolol tartrate (MT), was selected as a model drug for preparation of multi-walled carbon nanotubes (MWCNTs)-impregnated ethyl cellulose (EC) microspheres. The present investigation was aimed to increase encapsulation efficiency of MT with excellent adsorbent properties of MWCNTs. The unique surface area, stiffness, strength and resilience of MWCNTs have drawn much anticipation as carrier for highly water-soluble drugs. Carbon nanotubes drug adsorbate (MWCNTs:MT)-loaded EC microspheres were further optimized by the central composite design of the experiment. The effects of independent variables (MWCNTs:MT and EC:adsorbate) were evaluated on responses like entrapment efficiency (EE) and t 50 (time required for 50% drug release). The optimized batch was compared with drug alone EC microspheres. The results revealed high degree of improvement in encapsulation efficiency for MWCNTs:MT-loaded EC microspheres. In vitro drug release study exhibited complete release form drug alone microspheres within 15 h, while by the same time only 50-60% drug was released for MWCNTs-impregnated EC microspheres. The optimized batch was further characterized by various instrumental analyses such as scanning electron microscopy, powder X-ray diffraction and differential scanning calorimetry. The results endorse encapsulation of MWCNTs:MT adsorbate inside the matrix of EC microspheres, which might have resulted in enhanced encapsulation and sustained effect of MT. Hence, MWCNTs can be utilized as novel carriers for extended drug release and enhanced encapsulation of highly water-soluble drug, MT.

Adsorbate Diffusion on Transition Metal Nanoparticles

DTIC Science & Technology

2015-01-01

different sizes and shapes using density functional theory calculations. We show that nanoparticles bind adsorbates more strongly than the...structure theoretical methods, a quantitative study with accurate density functional theory (DFT) calculations is still missing. Here, we perform a...functional theory . The projector augmented wave (PAW) potentials29,30 were used for electron- ion interactions and the generalized gradient approximation

Green synthesis of tannin-hexamethylendiamine based adsorbents for efficient removal of Cr(VI).

PubMed

Liu, Qiang; Liu, Qinze; Liu, Bingsi; Hu, Tao; Liu, Weiliang; Yao, Jinshui

2018-06-15

Newly developed adsorbents, poly(tannin-hexamethylendiamine) (PTHA), were fabricated by varying the mole ratio of tannin (TA) and hexamethylendiamine (HA) under one-pot reaction. The specific forming process of the adsorbent which had undergone the transition from hydrogen bonds to covalent bonds was subsequently explored. Based on the efficiency of Cr(VI) removal from aqueous solution over all prepared adsorbents, the PTHA-4 (mole ratio of TA/HA = 1:12.5) exhibited an excellent adsorption behavior. Adsorption experiments affected by contact time and ionic strength have been conducted successively by PTHA-4, and the equilibrium was reached at 24 h. The kinetic data revealed that the adsorption was good agreement with pseudo-second order model and needed to undergo the rate-controlling step. The maximum adsorption capacity was 283.29 mg/g at 30 °C, relying on the isothermal curve suitably described by Langmuir model. Furthermore, toxic Cr(VI) had been reduced to the low toxic Cr(III) during adsorption process. The structures and adsorption performance of adsorbent were confirmed by means of SEM, FT-IR, XPS etc. Thus, the cheap-sustainable adsorbents have a superior feature for Cr(VI)-wastewater purification in future. Copyright © 2018 Elsevier B.V. All rights reserved.

PVDF membranes containing hybrid nanoparticles for adsorbing cationic dyes: physical insights and mechanism

NASA Astrophysics Data System (ADS)

Sharma, Maya; Madras, Giridhar; Bose, Suryasarathi

2016-07-01

In this study, Fe (iron) and Ag (silver) based adsorbents were synthesized using solution combustion and in situ reduction techniques. The synthesized adsorbents were comprehensively characterized by different techniques including electron microscopy, BET, XRD, Zeta potential etc. Three chlorinated cationic dyes used were malachite green, methyl violet and pyronin Y. These dyes were adsorbed on various synthesized adsorbents [iron III oxide (Fe2O3)], iron III oxide decorated silver nanoparticles by combustion synthesis technique [Fe2O3-Ag(C)] and iron III oxide decorated silver nanoparticles using in situ reduction, [Fe2O3-Ag (S)]. The isotherm and the adsorption kinetics have been studied systematically. The kinetic data can be explained by the pseudo second order model and the adsorption equilibrium followed Langmuir isotherm. The equilibrium and kinetics results suggest that Fe2O3-Ag(S) nanoparticles showed the maximum adsorption among all the adsorbents. Hence, Polyvinylidene fluoride based membranes containing Fe2O3-Ag(S) nanoparticles were prepared via phase inversion (precipitation immersion using DMF/water) technique. The adsorption kinetics were studied in detail and it was observed that the composite membrane showed synergistic improvement in dye adsorption. Such membranes can be used for water purification.

Investigations into the Effect of Current Velocity on Amidoxime-Based Polymeric Uranium Adsorbent Performance

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

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

2015-12-01

The Fuel Resources Program at the U.S. Department of Energy’s (DOE), Office of Nuclear Energy (DOE-NE) is developing adsorbent technology to extract uranium from seawater. This technology is being developed to provide a sustainable and economically viable supply of uranium fuel for nuclear reactors (DOE, 2010). Among the key environmental variables to understand for adsorbent deployment in the coastal ocean is what effect flow-rates or linear velocity has on uranium adsorption capacity. The goal is to find a flow conditions that optimize uranium adsorption capacity in the shortest exposure time. Understanding these criteria will be critical in choosing a locationmore » for deployment of a marine adsorbent farm. The objective of this study was to identify at what linear velocity the adsorption kinetics for uranium extraction starts to drop off due to limitations in mass transport of uranium to the surface of the adsorbent fibers. Two independent laboratory-based experimental approaches using flow-through columns and recirculating flumes for adsorbent exposure were used to assess the effect of flow-rate (linear velocity) on the kinetic uptake of uranium on amidoxime-based polymeric adsorbent material. Time series observations over a 56 day period were conducted with flow-through columns over a 35-fold range in linear velocity from 0.29 to 10.2 cm/s, while the flume study was conducted over a narrower 11-fold range, from 0.48 to 5.52 cm/s. These ranges were specifically chosen to focus on the lower end of oceanic currents and expand above and below the linear velocity of ~ 2.5 cm/s adopted for marine testing of adsorbent material at PNNL.« less

Removal of lead and zinc ions from water by low cost adsorbents.

PubMed

Mishra, P C; Patel, R K

2009-08-30

In this study, activated carbon, kaolin, bentonite, blast furnace slag and fly ash were used as adsorbent with a particle size between 100 mesh and 200 mesh to remove the lead and zinc ions from water. The concentration of the solutions prepared was in the range of 50-100 mg/L for lead and zinc for single and binary systems which are diluted as required for batch experiments. The effect of contact time, pH and adsorbent dosage on removal of lead and zinc by adsorption was investigated. The equilibrium time was found to be 30 min for activated carbon and 3h for kaolin, bentonite, blast furnace slag and fly ash. The most effective pH value for lead and zinc removal was 6 for activated carbon. pH value did not effect lead and zinc removal significantly for other adsorbents. Adsorbent doses were varied from 5 g/L to 20 g/L for both lead and zinc solutions. An increase in adsorbent doses increases the percent removal of lead and zinc. A series of isotherm studies was undertaken and the data evaluated for compliance was found to match with the Langmuir and Freundlich isotherm models. To investigate the adsorption mechanism, the kinetic models were tested, and it follows second order kinetics. Kinetic studies reveals that blast furnace slag was not effective for lead and zinc removal. The bentonite and fly ash were effective for lead and zinc removal.

Zirconium-based highly porous metal-organic framework (MOF-545) as an efficient adsorbent for vortex assisted-solid phase extraction of lead from cereal, beverage and water samples.

PubMed

Tokalıoğlu, Şerife; Yavuz, Emre; Demir, Selçuk; Patat, Şaban

2017-12-15

In this study, zirconium-based highly porous metal-organic framework, MOF-545, was synthesized and characterized. The surface area of MOF-545 was found to be 2192m 2 /g. This adsorbent was used for the first time as an adsorbent for the vortex assisted-solid phase extraction of Pb(II) from cereal, beverage and water samples. Lead in solutions was determined by FAAS. The optimal experimental conditions were as follows: the amount of MOF-545, 10mg; pH of sample, 7; adsorption and elution time, 15min; and elution solvent, 2mL of 1molL -1 HCl. Under the optimal conditions of the method, the limit of detection, preconcentration factor and precision as RSD% were found to be 1.78μgL -1 , 125 and 2.6%, respectively. The adsorption capacity of the adsorbent for lead was found to be 73mgg -1 . The method was successfully verified by analyzing two certified reference materials (BCR-482 Lichen and SPS-WW1 Batch 114) and spiked chickpea, bean, wheat, lentil, cherry juice, mineral water, well water and wastewater samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis of polydopamine-functionalized magnetic graphene and carbon nanotubes hybrid nanocomposites as an adsorbent for the fast determination of 16 priority polycyclic aromatic hydrocarbons in aqueous samples.

PubMed

Chen, Kun; Jin, Rongrong; Luo, Chen; Song, Guoxin; Hu, Yaoming; Cheng, Hefa

2018-04-01

A novel adsorbent made of polydopamine-functionalized magnetic graphene and carbon nanotubes hybrid nanocomposite was synthesized and applied to determine 16 priority polycyclic aromatic hydrocarbons by magnetic solid phase extraction in water samples. FTIR spectroscopy, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy consistently indicate that the synthesized adsorbents are made of core-shell nanoparticles well dispersed on the surface of graphene and carbon nanotubes. The major factors affecting the extraction efficiency, including the pH value of samples, the amount of adsorbent, adsorption time and desorption time, type and volume of desorption solvent, were systematically optimized. Under the optimum extraction conditions, a linear response was obtained for polycyclic aromatic hydrocarbons between concentrations of 10 and 500 ng/L with the correlation coefficients ranging from 0.9958 to 0.9989, and the limits of detection (S/N = 3) were between 0.1 and 3.0 ng/L. Satisfactory results were also obtained when applying these magnetic graphene/carbon nanotubes/polydopamine hybrid nanocomposites to detect polycyclic aromatic hydrocarbons in several environmental aqueous samples. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Precisions Measurement for the Grasp of Welding Deformation amount of Time Series for Large-Scale Industrial Products

NASA Astrophysics Data System (ADS)

Abe, R.; Hamada, K.; Hirata, N.; Tamura, R.; Nishi, N.

2015-05-01

As well as the BIM of quality management in the construction industry, demand for quality management of the manufacturing process of the member is higher in shipbuilding field. The time series of three-dimensional deformation of the each process, and are accurately be grasped strongly demanded. In this study, we focused on the shipbuilding field, will be examined three-dimensional measurement method. The shipyard, since a large equipment and components are intricately arranged in a limited space, the installation of the measuring equipment and the target is limited. There is also the element to be measured is moved in each process, the establishment of the reference point for time series comparison is necessary to devise. In this paper will be discussed method for measuring the welding deformation in time series by using a total station. In particular, by using a plurality of measurement data obtained from this approach and evaluated the amount of deformation of each process.

Characterization and testing of amidoxime-based adsorbent materials to extract uranium from natural seawater

DOE PAGES

Kuo, Li-Jung; Janke, Christopher James; Wood, Jordana; ...

2015-11-19

Extraction of uranium (U) from seawater for use as a nuclear fuel is a significant challenge due to the low concentration of U in seawater (~3.3 ppb) and difficulties to selectively extract U from the background of major and trace elements in seawater. The Pacific Northwest National Laboratory (PNNL) s Marine Sciences Laboratory (MSL) has been serving as a marine test site for determining performance characteristics (adsorption capacity, adsorption kinetics, and selectivity) of novel amidoxime-based polymeric adsorbents developed at Oak Ridge National Laboratory (ORNL) under natural seawater exposure conditions. This report describes the performance of three formulations (38H, AF1, AI8)more » of amidoxime-based polymeric adsorbent produced at ORNL in MSL s ambient seawater testing facility. The adsorbents were produced in two forms, fibrous material (40-100 mg samples) and braided material (5-10 g samples), exposed to natural seawater using flow-through columns and recirculating flumes. All three formulations demonstrated high 56 day uranium adsorption capacity (>3 gU/kg adsorbent). The AF1 formulation had the best uranium adsorption performance, with 56-day capacity of 3.9 g U/kg adsorbent, saturation capacity of 5.4 g U/kg adsorbent, and ~25 days half-saturation time. The two exposure methods, flow-through columns and flumes were demonstrated to produce similar performance results, providing confidence that the test methods were reliable, that scaling up from 10 s of mg quantities of exposure in flow-through columns to gram quantities in flumes produced similar results, and that the manufacturing process produces a homogenous adsorbent. Adsorption kinetics appear to be element specific, with half-saturation times ranging from minutes for the major cations in seawater to 8-10weeks for V and Fe. Reducing the exposure time provides a potential pathway to improve the adsorption capacity of U by reducing the V/U ratio on the adsorbent.« less

Characterization and Testing of Amidoxime-Based Adsorbent Materials to Extract Uranium from Natural Seawater

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

Kuo, Li-Jung; Janke, Christopher J.; Wood, Jordana R.

Extraction of uranium (U) from seawater for use as a nuclear fuel is a significant challenge due to the low concentration of U in seawater (~3.3 ppb) and difficulties to selectively extract U from the background of major and trace elements in seawater. The Pacific Northwest National Laboratory (PNNL)’s Marine Sciences Laboratory (MSL) has been serving as a marine test site for determining performance characteristics (adsorption capacity, adsorption kinetics, and selectivity) of novel amidoxime-based polymeric adsorbents developed at Oak Ridge National Laboratory (ORNL) under natural seawater exposure conditions. This manuscript describes the performance of three formulations (38H, AF1, AI8) ofmore » amidoxime-based polymeric adsorbents produced at ORNL in MSL’s ambient seawater testing facility. The adsorbents were produced in two forms, fibrous material (40-100 mg samples) and braided material (5-10 g samples), and exposed to natural seawater using flow-through columns and recirculating flumes. All three formulations demonstrated high 56 day uranium adsorption capacity (>3 g U/kg adsorbent). The AF1 formulation had the best uranium adsorption performance, with a 56 day capacity of 3.9 g U/ kg adsorbent, a saturation capacity of 5.4 g U/kg adsorbent, and ~25 days half-saturation time. The two exposure methods, flowthrough columns and flumes, were demonstrated to produce similar performance results, providing confidence that the test methods were reliable, that scaling up from 10’s of mg quantities of exposure in flow-through columns to gram quantities in flumes produced similar results, and confirm that the manufacturing process produces a homogeneous adsorbent. Adsorption kinetics appear to be element specific, with half-saturation times ranging from minutes for the major cations in seawater, to 8-10 weeks for V and Fe. Reducing the exposure time provides a potential pathway to improve the adsorption capacity of U by reducing the V/U ratio on the adsorbent.« less

Characterization and testing of amidoxime-based adsorbent materials to extract uranium from natural seawater

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

Kuo, Li-Jung; Janke, Christopher James; Wood, Jordana

Extraction of uranium (U) from seawater for use as a nuclear fuel is a significant challenge due to the low concentration of U in seawater (~3.3 ppb) and difficulties to selectively extract U from the background of major and trace elements in seawater. The Pacific Northwest National Laboratory (PNNL) s Marine Sciences Laboratory (MSL) has been serving as a marine test site for determining performance characteristics (adsorption capacity, adsorption kinetics, and selectivity) of novel amidoxime-based polymeric adsorbents developed at Oak Ridge National Laboratory (ORNL) under natural seawater exposure conditions. This report describes the performance of three formulations (38H, AF1, AI8)more » of amidoxime-based polymeric adsorbent produced at ORNL in MSL s ambient seawater testing facility. The adsorbents were produced in two forms, fibrous material (40-100 mg samples) and braided material (5-10 g samples), exposed to natural seawater using flow-through columns and recirculating flumes. All three formulations demonstrated high 56 day uranium adsorption capacity (>3 gU/kg adsorbent). The AF1 formulation had the best uranium adsorption performance, with 56-day capacity of 3.9 g U/kg adsorbent, saturation capacity of 5.4 g U/kg adsorbent, and ~25 days half-saturation time. The two exposure methods, flow-through columns and flumes were demonstrated to produce similar performance results, providing confidence that the test methods were reliable, that scaling up from 10 s of mg quantities of exposure in flow-through columns to gram quantities in flumes produced similar results, and that the manufacturing process produces a homogenous adsorbent. Adsorption kinetics appear to be element specific, with half-saturation times ranging from minutes for the major cations in seawater to 8-10weeks for V and Fe. Reducing the exposure time provides a potential pathway to improve the adsorption capacity of U by reducing the V/U ratio on the adsorbent.« less

The First Layer of 4He, H2, and Ne Adsorbed on HiPco™ Carbon Nanotube Bundles

NASA Astrophysics Data System (ADS)

Vilches, O. E.; Ramachandran, S.; Wilson, T. A.; Dash, J. G.

2006-09-01

We summarize results from AC and DC heat capacity measurements of 4He, H2, and Ne adsorbed on HiPco™ purified, closed-end single-wall carbon nanotube bundles (SWNTB) for the first adsorbed layer. We find two regions in the coverage domain: below ≈1/3 monolayer the adsorbate occupies high binding energy sites, mostly the external grooves of the bundles, while above ≈1/3 monolayer the external graphene surface is covered. No phase transitions have been observed at any temperature for all the adsorbates, a range of T where two-dimensional phases and phase transitions are seen for the same adsorbates deposited on exfoliated graphite.

Magnetized graphene layers synthesized on the carbon nanofibers as novel adsorbent for the extraction of polycyclic aromatic hydrocarbons from environmental water samples.

PubMed

Rezvani-Eivari, Mostafa; Amiri, Amirhassan; Baghayeri, Mehdi; Ghaemi, Ferial

2016-09-23

The application of magnetized graphene (G) layers synthesized on the carbon nanofibers (CNFs) (m-G/CNF) was investigated as novel adsorbent for the magnetic solid-phase extraction (MSPE) of polycyclic aromatic hydrocarbons (PAHs) in water samples followed by gas chromatography-flame ionization detector (GC-FID). Six important parameters, affecting the extraction efficiency of PAHs, including: amount of adsorbent, adsorption and desorption times, type and volume of the eluent solvent and salt content of the sample were evaluated. The optimum extraction conditions were obtained as: 5min for extraction time, 20mg for sorbent amount, dichloromethane as desorption solvent, 1mL for desorption solvent volume, 5min for desorption time and 15% (w/v) for NaCl concentration. Good performance data were obtained at the optimized conditions. The calibration curves were linear over the concentration ranges from 0.012 to 100ngmL(-1) with correlation coefficients (r) between 0.9950 and 0.9967 for all the analytes. The limits of detection (LODs, S/N=3) of the proposed method for the studied PAHs were 0.004-0.03ngmL(-1). The relative standard deviations (RSDs) for five replicates at two concentration levels (0.1 and 50ngmL(-1)) of PAHs were ranged from 3.4 to 5.7%. Appropriate relative recovery values, in the range of 95.5-99.9%, were also obtained for the real water sample analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

Reorientational Dynamics of Enzymes Adsorbed on Quartz: A Temperature-Dependent Time-Resolved TIRF Anisotropy Study

PubMed Central

Czeslik, C.; Royer, C.; Hazlett, T.; Mantulin, W.

2003-01-01

The preservation of enzyme activity and protein binding capacity upon protein adsorption at solid interfaces is important for biotechnological and medical applications. Because these properties are partly related to the protein flexibility and mobility, we have studied the internal dynamics and the whole-body reorientational rates of two enzymes, staphylococcal nuclease (SNase) and hen egg white lysozyme, over the temperature range of 20–80°C when the proteins are adsorbed at the silica/water interface and, for comparison, when they are dissolved in buffer. The data were obtained using a combination of two experimental techniques, total internal reflection fluorescence spectroscopy and time-resolved fluorescence anisotropy measurements in the frequency domain, with the protein Trp residues as intrinsic fluorescence probes. It has been found that the internal dynamics and the whole-body rotation of SNase and lysozyme are markedly reduced upon adsorption over large temperature ranges. At elevated temperatures, both protein molecules appear completely immobilized and the fractional amplitudes for the whole-body rotation, which are related to the order parameter for the local rotational freedom of the Trp residues, remain constant and do not approach zero. This behavior indicates that the angular range of the Trp reorientation within the adsorbed proteins is largely restricted even at high temperatures, in contrast to that of the dissolved proteins. The results of this study thus provide a deeper understanding of protein activity at solid surfaces. PMID:12668461

Structure of Irreversibly Adsorbed Star Polymers

NASA Astrophysics Data System (ADS)

Akgun, Bulent; Aykan, Meryem Seyma; Canavar, Seda; Satija, Sushil K.; Uhrig, David; Hong, Kunlun

Formation of irreversibly adsorbed polymer chains on solid substrates have a huge impact on the wetting, glass transition, aging and polymer chain mobility in thin films. In recent years there has been many reports on the formation, kinetics and dynamics of these layers formed by linear homopolymers. Recent studies showed that by varying the number of polymer arms and arm molecular weight one can tune the glass transition temperature of thin polymer films. Using polymer architecture as a tool, the behavior of thin films can be tuned between the behavior of linear chains and soft colloids. We have studied the effect of polymer chain architecture on the structure of dead layer using X-ray reflectivity (XR) and atomic force microscopy. Layer thicknesses and densities of flattened and loosely adsorbed chains has been measured for linear, 4-arm, and 8-arm star polymers with identical total molecular weight as a function of substrate surface energy, annealing temperature and annealing time. Star polymers have been synthesized using anionic polymerization. XR measurements showed that 8-arm star PS molecules form the densest and the thickest dead layers among these three molecules.

Effect of biofouling on the performance of amidoxime-based polymeric uranium adsorbents

DOE PAGES

Park, Jiyeon; Gill, Gary A.; Strivens, Jonathan E.; ...

2016-01-27

Here, the Marine Science Laboratory at the Pacific Northwest National Laboratory evaluated the impact of biofouling on uranium adsorbent performance. A surface modified polyethylene adsorbent fiber provided by Oak Ridge National Laboratory, AF adsorbent, was tested either in the presence or absence of light to simulate deployment in shallow or deep marine environments. 42-day exposure tests in column and flume settings showed decreased uranium uptake by biofouling. Uranium uptake was reduced by up to 30 %, in the presence of simulated sunlight, which also increased biomass accumulation and altered the microbial community composition on the fibers. These results suggest thatmore » deployment below the photic zone would mitigate the effects of biofouling, resulting in greater yields of uranium extracted from seawater.« less

The kinetics of influenza-virus adsorption on iron oxide in the process of viral purification and concentration

PubMed Central

Larin, N. M.; Gallimore, P. H.

1971-01-01

This paper reports a study carried out to clarify the mechanisms involved in adsorption of influenza A and B viruses on iron oxide. Accordingly, the amounts of virus that are adsorbed from virus suspensions of varying concentrations per unit surface area of magnetic or non-magnetic oxide at fixed temperature and time have been determined. The principles involved are clearly the same as those involved in multiple equilibria during the interaction of particles with a large number of combining sites with different intrinsic affinity. Consequently, the amount of virus that is adsorbed per unit mass of iron oxide depends on the size of the adsorbent area, not on its magnetic property. Owing to a significant difference between the affinities of influenza A and B particles for the binding sites on iron oxide, unit surface area of the adsorbent is invariably capable of adsorbing significantly greater amounts of influenza A than B particles. The practical implications of these findings are that a better understanding of the mechanisms involved in virus adsorption on iron oxide will permit a more efficient separation of virus particles from impurities. The simplicity and the rapidity of the technique and the cheapness of the equipment required suggest that the iron oxide method is of great value for both small- or large-scale viral purification, whether it is used as a single step procedure or as a primary step followed by zonal separation. PMID:5291749

Investigation of the SERS Spectra of Hydroquinone Molecule Adsorbed on Titanium Dioxide

NASA Astrophysics Data System (ADS)

Polubotko, A. M.; Chelibanov, V. P.

2018-01-01

The paper analyzes the SERS spectrum of hydroquinone adsorbed on nanoparticles of titanium dioxide (TiO2). It is seen that the enhancement is stronger for a larger mean size of nanoparticles that is in agreement with an electrostatic approximation. In addition, it is found that there are the lines, which are forbidden in usual Raman spectra. There is also an enhancement caused both by the normal and tangential components of the electric field. This result is in agreement with the theory of SERS on semiconductor and dielectric substrates. The discovery of the forbidden lines indicates on the sufficiently large role of the strong quadrupole light-molecule interaction in such a system.

Characterization of Adsorbents for Cytokine Removal from Blood in an In Vitro Model.

PubMed

Harm, Stephan; Gabor, Franz; Hartmann, Jens

2015-01-01

Cytokines are basic targets that have to be removed effectively in order to improve the patient's health status in treating severe inflammation, sepsis, and septic shock. Although there are different adsorbents commercially available, the success of their clinical use is limited. Here, we tested different adsorbents for their effective removal of cytokines from plasma and the resulting effect on endothelial cell activation. The three polystyrene divinylbenzene (PS-DVB) based adsorbents Amberchrom CG161c and CG300m and a clinically approved haemoperfusion adsorbent (HAC) were studied with regard to cytokine removal in human blood. To induce cytokine release from leucocytes, human blood cells were stimulated with 1 ng/ml LPS for 4 hours. Plasma was separated and adsorption experiments in a dynamic model were performed. The effect of cytokine removal on endothelial cell activation was evaluated using a HUVEC-based cell culture model. The beneficial outcome was assessed by measuring ICAM-1, E-selectin, and secreted cytokines IL-8 and IL-6. Additionally the threshold concentration for HUVEC activation by TNF-α and IL-1β was determined using this cell culture model. CG161c showed promising results in removing the investigated cytokines. Due to its pore size the adsorbent efficiently removed the key factor TNF-α, outperforming the commercially available adsorbents. The CG161c treatment reduced cytokine secretion and expression of cell adhesion molecules by HUVEC which underlines the importance of effective removal of TNF-α in inflammatory diseases. These results confirm the hypothesis that cytokine removal from the blood should approach physiological levels in order to reduce endothelial cell activation.

Characterization of Adsorbents for Cytokine Removal from Blood in an In Vitro Model

PubMed Central

Gabor, Franz; Hartmann, Jens

2015-01-01

Introduction. Cytokines are basic targets that have to be removed effectively in order to improve the patient's health status in treating severe inflammation, sepsis, and septic shock. Although there are different adsorbents commercially available, the success of their clinical use is limited. Here, we tested different adsorbents for their effective removal of cytokines from plasma and the resulting effect on endothelial cell activation. Methods. The three polystyrene divinylbenzene (PS-DVB) based adsorbents Amberchrom CG161c and CG300m and a clinically approved haemoperfusion adsorbent (HAC) were studied with regard to cytokine removal in human blood. To induce cytokine release from leucocytes, human blood cells were stimulated with 1 ng/ml LPS for 4 hours. Plasma was separated and adsorption experiments in a dynamic model were performed. The effect of cytokine removal on endothelial cell activation was evaluated using a HUVEC-based cell culture model. The beneficial outcome was assessed by measuring ICAM-1, E-selectin, and secreted cytokines IL-8 and IL-6. Additionally the threshold concentration for HUVEC activation by TNF-α and IL-1β was determined using this cell culture model. Results. CG161c showed promising results in removing the investigated cytokines. Due to its pore size the adsorbent efficiently removed the key factor TNF-α, outperforming the commercially available adsorbents. The CG161c treatment reduced cytokine secretion and expression of cell adhesion molecules by HUVEC which underlines the importance of effective removal of TNF-α in inflammatory diseases. Conclusion. These results confirm the hypothesis that cytokine removal from the blood should approach physiological levels in order to reduce endothelial cell activation. PMID:26770992

Effects of surface imperfections on the binding of CH 3OH and H 2O on FeS 2(100): using adsorbed Xe as a probe of mineral surface structure

NASA Astrophysics Data System (ADS)

Guevremont, J. M.; Strongin, D. R.; Schoonen, M. A. A.

1997-11-01

Studies are presented that investigate the adsorption and binding of CH 3OH and H 2O on the atomically clean (100) crystallographic plane of pyrite, FeS 2. Temperature programmed desorption suggests that both reactants adsorb molecularly at 90 K and desorb thermally between 170 and 400 K depending on the surface coverage. Photoemission of adsorbed xenon (PAX) suggests that the surface of pyrite is heterogeneous and contains a significant fraction of defect sites that are believed to be, at least in part, anion vacancy or sulfur-deficient sites. An upper limit of 0.2 is proposed for the fraction of surface sites that are defects on FeS 2(100). PAX indicates that these defect sites at low adsorbate coverage serve as the exclusive binding sites for H 2O and CH 3OH adsorbate. We speculate, on the basis of our ability to interpret PAX data for pyrite, that PAX may be of use for understanding the effect of short range order on adsorbate binding on other complex mineral surfaces. On the basis of high resolution electron energy loss spectroscopy, it is found that some dissociation of the adsorbate occurs on the pyrite. Vibrational data obtained with this technique suggests that FeO species result from the adsorbate decomposition. After saturation of the defect sites, further molecular adsorption is accommodated on the less reactive surface that we postulate is largely disulfide, the characteristic structural group of pyrite.

29 CFR 4219.13 - Amount of liability for de minimis amounts.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 29 Labor 9 2011-07-01 2011-07-01 false Amount of liability for de minimis amounts. 4219.13 Section... Redetermination of Withdrawal Liability Upon Mass Withdrawal § 4219.13 Amount of liability for de minimis amounts. An employer that is liable for de minimis amounts shall be liable to the plan for the amount by which...

29 CFR 4219.13 - Amount of liability for de minimis amounts.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 9 2010-07-01 2010-07-01 false Amount of liability for de minimis amounts. 4219.13 Section... Redetermination of Withdrawal Liability Upon Mass Withdrawal § 4219.13 Amount of liability for de minimis amounts. An employer that is liable for de minimis amounts shall be liable to the plan for the amount by which...

Role of air bubbles overlooked in the adsorption of perfluorooctanesulfonate on hydrophobic carbonaceous adsorbents.

PubMed

Meng, Pingping; Deng, Shubo; Lu, Xinyu; Du, Ziwen; Wang, Bin; Huang, Jun; Wang, Yujue; Yu, Gang; Xing, Baoshan

2014-12-02

Hydrophobic interaction has been considered to be responsible for adsorption of perfluorooctanesulfonate (PFOS) on the surface of hydrophobic adsorbents, but the long C-F chain in PFOS is not only hydrophobic but also oleophobic. In this study, for the first time we propose that air bubbles on the surface of hydrophobic carbonaceous adsorbents play an important role in the adsorption of PFOS. The level of adsorption of PFOS on carbon nanotubes (CNTs), graphite (GI), graphene (GE), and powdered activated carbon (PAC) decreases after vacuum degassing. Vacuum degassing time and pressure significantly affect the removal of PFOS by these adsorbents. After vacuum degassing at 0.01 atm for 36 h, the extent of removal of PFOS by the pristine CNTs and GI decreases 79% and 74%, respectively, indicating the main contribution of air bubbles to PFOS adsorption. When the degassed solution is recontacted with air during the adsorption process, the removal of PFOS recovers to the value obtained without vacuum degassing, further verifying the key role of air bubbles in PFOS adsorption. By theoretical calculation, the distribution of PFOS in air bubbles on the adsorbent surfaces is discussed, and a new schematic sorption model of PFOS on carbonaceous adsorbents in the presence of air bubbles is proposed. The accumulation of PFOS at the interface of air bubbles on the adsorbents is primarily responsible for its adsorption, providing a new mechanistic insight into the transport, fate, and removal of PFOS.

Tetracycline removal from water by adsorption/bioadsorption on activated carbons and sludge-derived adsorbents.

PubMed

Rivera-Utrilla, José; Gómez-Pacheco, Carla V; Sánchez-Polo, Manuel; López-Peñalver, Jesús J; Ocampo-Pérez, Raúl

2013-12-15

The objective of this study was to analyze the behavior of activated carbons with different chemical and textural natures in the adsorption of three tetracyclines (TCs) (tetracycline, oxytetracycline, and chlortetracycline). We also assessed the influence of the solution pH and ionic strength on the adsorption of these compounds and studied their removal by the combined use of microorganisms and activated carbon (bioadsorption). Sludge-derived materials were also used to remove TC from water. The capacity of these materials to adsorb TC was very high and was much greater than that of commercial activated carbon. This elevated adsorption capacity (512.1-672.0 mg/g) is explained by the high tendency of TC to form complex ions with some of the metal ions present in these materials. The medium pH and presence of electrolytes considerably affected TCs adsorption on commercial activated carbon. These results indicate that electrostatic adsorbent-adsorbate interactions play an important role in TC adsorption processes when conducted at pH values that produce TC deprotonation. The presence of bacteria during the TCs adsorption process decreases their adsorption/bioadsorption on the commercial activated carbon, weakening interactions between the adsorbate and the microfilm formed on the carbon surface. The adsorptive capacity was considerably lower in dynamic versus static regime, attributable to problems of TC diffusion into carbon pores and the shorter contact time between adsorbate and adsorbent. Copyright © 2013 Elsevier Ltd. All rights reserved.

The application of textile sludge adsorbents for the removal of Reactive Red 2 dye.

PubMed

Sonai, Gabriela G; de Souza, Selene M A Guelli U; de Oliveira, Débora; de Souza, Antônio Augusto U

2016-03-01

Sludge from the textile industry was used as a low-cost adsorbent to remove the dye Reactive Red 2 from an aqueous solution. Adsorbents were prepared through the thermal and chemical treatment of sludge originating from physical-chemical (PC) and biological (BIO) effluent treatment processes. The adsorbent characterization was carried out through physical-chemical analysis, X-ray fluorescence (XRF) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, pHPZC determination, Boehm titration method, Brunauer-Emmett-Teller (BET) surface area analysis and scanning electron microscopy (SEM). Batch kinetic experiments and adsorption isotherm modeling were conducted under different pH and temperature conditions. The results for the kinetic studies indicate that the adsorption processes associated with these systems can be described by a pseudo-second-order model and for the equilibrium data the Langmuir model provided the best fit. The adsorption was strongly dependent on the pH but not on the temperature within the ranges studied. The maxima adsorption capacities were 159.3 mg g(-1) for the BIO adsorbent and 213.9 mg g(-1) for PC adsorbent at pH of 2 and 25 °C. Copyright © 2015 Elsevier Ltd. All rights reserved.

Rigorous Mathematical Modeling of Adsorption System with Electrothermal Regeneration of the Used Adsorbent

DTIC Science & Technology

2006-12-01

DISTRIBUTION STATEMENT. ________//signature//________________ ________//signature//________________ PATRICK D. SULLIVAN, Ph.D., P.E. SANDRA R ...adsorber, at r =1.24 cm: (a) gas phase; (b) solid phase..................................................................................... 30 46 The...34 57 Axial profiles of the gas velocity during adsorption in the 2-cartridge adsorber at r =1.25cm..... 34 60

First-principles study of pollutant molecules absorbed on polymeric adsorbents using the vdW-DF2 functional

NASA Astrophysics Data System (ADS)

Zhu, Jinguo; Wang, Yapeng; Tian, Ting; Zhang, Qianfan

2018-03-01

Polymeric adsorbents have been attracting increasing attention because of their favorable structrual properties and effectiveness of solving small molecules contaminants. However, due to the absence of deep insight into the adsorption mechanism of polymeric adsorbents, researches on new polymeric adsorbents can only be carried out by repeated experiments and tests, which is extremely inefficient. Therefore, investigating the adsorption process of polymeric adsorbents, especially the mechanism of adsorbing various air pollutant molecules by materials modelling and simulation, is of great significance. Here in this work, we systematically studied the adsorption mechanism by first-principles computation with van der Waals interaction. It demonstrates that the adsorption between them was pure physisorption originating from the hydrogen bond and intermolecular forces consisting of Keesom force, Debye force and London dispersion force. The proportions of these forces varied according to different adsorption systems. The adsorption effects were determined by the polymers’ dipole moment and polarizability. The adsorption performance of some polymers with special structures was also investigated to explore their possibility as potential adsorbents. The results of our simulation can provide some guidance for developing new polymeric adsorbents with better performance.

Porous materials as high performance adsorbents for CO2 capture, gas separation and purification

NASA Astrophysics Data System (ADS)

Wang, Jun

Global warming resulted from greenhouse gases emission has received a widespread attention. Among the greenhouse gases, CO2 contributes more than 60% to global warming due to its huge emission amount. The flue gas contains about 15% CO2 with N2 as the balance. If CO2 can be separated from flue gas, the benefit is not only reducing the global warming effect, but also producing pure CO2 as a very useful industry raw material. Substantial progress is urgent to be achieved in an industrial process. Moreover, energy crisis is one of the biggest challenges for all countries due to the short life of fossil fuels, such as, petroleum will run out in 50 years and coal will run out in 150 years according to today's speed. Moreover, the severe pollution to the environment caused by burning fossil fuels requires us to explore sustainable, environment-friendly, and facile energy sources. Among several alternative energy sources, natural gas is one of the most promising alternative energy sources due to its huge productivity, abundant feed stock, and ease of generation. In order to realize a substantial adsorption process in industry, synthesis of new adsorbents or modification of existing adsorbent with improved properties has become the most critical issue. This dissertation reports systemic characterization and development of five serials of novel adsorbents with advanced adsorption properties. In chapter 2, nitrogen-doped Hypercross-linking Polymers (HCPs) have been synthesized successfully with non-carcinogenic chloromethyl methyl ether (CME) as the cross-linking agent within a single step. Texture properties, surface morphology, CO2/N2 selectivity, and adsorption heat have been presented and demonstrated properly. A comprehensive discussion on factors that affect the CO2 adsorption and CO2/N 2 separation has also been presented. It was found that high micropore proportion and N-content could effectively enhance CO2 uptake and CO2/N2 separation selectivity. In chapter 3, a

Adsorption of mercury by carbonaceous adsorbents prepared from rubber of tyre wastes.

PubMed

Manchón-Vizuete, E; Macías-García, A; Nadal Gisbert, A; Fernández-González, C; Gómez-Serrano, V

2005-03-17

Rubber from tyre wastes has been used to prepare carbonaceous adsorbents and the products obtained have been tested as adsorbents for mercury in aqueous solution. The adsorbents have been prepared by applying thermal, chemical and combined (thermal and chemical or vice versa) treatments. Tyre rubber has been: heated at 400 or 900 degrees C for 2 h in N2, chemically-treated with H2SO4, HNO3 or H2SO4/HNO3 solution for 24 h, and in two successive steps first heated at 400 degrees C for 2h in N2 and then treated with a H2SO4/HNO3 solution for 24 h, or vice versa. Resultant products have been characterised in terms of elementary composition and textural properties. The adsorption of mercury has been studied from kinetic and equilibrium standpoints. The treatments effected to tyre rubber decrease the carbon content and the hydrogen content. The oxygen content and the nitrogen content increase for the chemically-treated products. The heat treatment of tyre rubber results in a larger development of surface area, microporosity, and mesoporosity than the chemical treatments. These treatments, however, produce a great creation of macropores. In comparison to the starting rubber, the adsorption process of mercury is faster when the material is heated or treated with the H2SO4, HNO3 or 1:3 H2SO4/HNO3 solution. These adsorbents are either a non-porous solid or possess a high mesopore volume or a wide pore size distribution in the macropore range. The adsorption capacity is larger for products prepared by heat, chemical and combined treatments of the rubber. A common textural characteristic of these adsorbents is their better developed microporosity. The ability to adsorb mercury is higher for the heated products than for the chemically-treated ones. The maximum adsorption of mercury is 211 mg g(-1). The constant Kf of the Freundlich equation is as high as 108.9 mg g(-1).

CO oxidation reaction on Pt(111) studied by the dynamic Monte Carlo method including lateral interactions of adsorbates.

PubMed

Nagasaka, Masanari; Kondoh, Hiroshi; Nakai, Ikuyo; Ohta, Toshiaki

2007-01-28

The dynamics of adsorbate structures during CO oxidation on Pt(111) surfaces and its effects on the reaction were studied by the dynamic Monte Carlo method including lateral interactions of adsorbates. The lateral interaction energies between adsorbed species were calculated by the density functional theory method. Dynamic Monte Carlo simulations were performed for the oxidation reaction over a mesoscopic scale, where the experimentally determined activation energies of elementary paths were altered by the calculated lateral interaction energies. The simulated results reproduced the characteristics of the microscopic and mesoscopic scale adsorbate structures formed during the reaction, and revealed that the complicated reaction kinetics is comprehensively explained by a single reaction path affected by the surrounding adsorbates. We also propose from the simulations that weakly adsorbed CO molecules at domain boundaries promote the island-periphery specific reaction.

Carbon dioxide adsorbents containing magnesium oxide suitable for use at high temperatures

DOEpatents

Mayorga, Steven Gerard; Weigel, Scott Jeffrey; Gaffney, Thomas Richard; Brzozowski, Jeffrey Richard

2001-01-01

Adsorption of carbon dioxide from gas streams at temperatures in the range of 300 to 500.degree. C. is carried out with a solid adsorbent containing magnesium oxide, preferably promoted with an alkali metal carbonate or bicarbonate so that the atomic ratio of alkali metal to magnesium is in the range of 0.006 to 2.60. Preferred adsorbents are made from the precipitate formed on addition of alkali metal and carbonate ions to an aqueous solution of a magnesium salt. Atomic ratios of alkali metal to magnesium can be adjusted by washing the precipitate with water. Low surface area adsorbents can be made by dehydration and CO.sub.2 removal of magnesium hydroxycarbonate, with or without alkali metal promotion. The process is especially valuable in pressure swing adsorption operations.

Recycling of spent adsorbents for oxyanions and heavy metal ions in the production of ceramics.

PubMed

Verbinnen, Bram; Block, Chantal; Van Caneghem, Jo; Vandecasteele, Carlo

2015-11-01

Spent adsorbents for oxyanion forming elements and heavy metals are classified as hazardous materials and they are typically treated by stabilization/solidification before landfilling. The use of lime or cement for stabilization/solidification entails a high environmental impact and landfilling costs are high. This paper shows that mixing spent adsorbents in the raw material for the production of ceramic materials is a valuable alternative to stabilize oxyanion forming elements and heavy metals. The produced ceramics can be used as construction material, avoiding the high economic and environmental impact of stabilization/solidification followed by landfilling. To study the stabilization of oxyanion forming elements and heavy metals during the production process, two series of experiments were performed. In the first series of experiments, the main pollutant, Mo was adsorbed onto iron-based adsorbents, which were then mixed with industrial sludge (3 w/w%) and heated at 1100°C for 30 min. Mo was chosen, as this element is easily adsorbed onto iron-based adsorbents and it is the element that is the most difficult to stabilize (i.e. the highest temperatures need to be reached before the concentrations in the leachate are reduced). Leaching concentration from the 97/3 sludge/adsorbent mixture before heating ranged between 85 and 154 mg/kg; after the heating process they were reduced to 0.42-1.48 mg/kg. Mo was actually stabilized, as the total Mo concentration after addition was not affected by the heat treatment. In the second series of experiments, the sludge was spiked with other heavy metals and oxyanion forming elements (Cr, Ni, Cu, Zn, As, Cd and Pb) in concentrations 5 times higher than the initial concentrations; after heat treatment the leachate concentrations were below the regulatory limit values. The incorporation of spent adsorbents in ceramic materials is a valuable and sustainable alternative to the existing treatment methods, saving raw materials in the

Smooth deuterated cellulose films for the visualisation of adsorbed bio-macromolecules

PubMed Central

Su, Jielong; Raghuwanshi, Vikram S.; Raverty, Warwick; Garvey, Christopher J.; Holden, Peter J.; Gillon, Marie; Holt, Stephen A.; Tabor, Rico; Batchelor, Warren; Garnier, Gil

2016-01-01

Novel thin and smooth deuterated cellulose films were synthesised to visualize adsorbed bio-macromolecules using contrast variation neutron reflectivity (NR) measurements. Incorporation of varying degrees of deuteration into cellulose was achieved by growing Gluconacetobacter xylinus in deuterated glycerol as carbon source dissolved in growth media containing D2O. The derivative of deuterated cellulose was prepared by trimethylsilylation(TMS) in ionic liquid(1-butyl-3-methylimidazolium chloride). The TMS derivative was dissolved in toluene for thin film preparation by spin-coating. The resulting film was regenerated into deuterated cellulose by exposure to acidic vapour. A common enzyme, horseradish peroxidase (HRP), was adsorbed from solution onto the deuterated cellulose films and visualized by NR. The scattering length density contrast of the deuterated cellulose enabled accurate visualization and quantification of the adsorbed HRP, which would have been impossible to achieve with non-deuterated cellulose. The procedure described enables preparing deuterated cellulose films that allows differentiation of cellulose and non-deuterated bio-macromolecules using NR. PMID:27796332

Amine-functionalized mesoporous ZSM-5 zeolite adsorbents for carbon dioxide capture

NASA Astrophysics Data System (ADS)

Wang, Yisong; Du, Tao; Song, Yanli; Che, Shuai; Fang, Xin; Zhou, Lifeng

2017-11-01

ZSM-5 type zeolite with mesoporous structure was prepared and then amine-functionalized with tetraethylenepentamine (TEPA) by wet impregnation method to form a series of CO2 adsorbents (ZTx). The structural properties of ZSM-5 and ZTx were characterized by XRD, FTIR, TGA/DTG, nitrogen adsorption/desorption, SEM and EDX techniques. The adsorption capacity of the adsorbents with different amine loading was measured at a temperature from 40 to 100 °C and the adsorption capacity of ZT7 was 1.80 mmol/g at 100 °C. The adsorption process and mechanism were studied by fitting the experimental data used the three adsorption kinetic models, and a complex physical and chemical mixing process was produced as the amine entered the surface and pore size of the zeolite. The high adsorption selectivity at 10% CO2 concentration and the stability of the five adsorption desorption cycles indicated that ZT7 is a suitable and promising CO2 adsorbent for the purification of industrial flue gas.

Elimination of persistent organic pollutants from fish oil with solid adsorbents.

PubMed

Ortiz, X; Carabellido, L; Martí, M; Martí, R; Tomás, X; Díaz-Ferrero, J

2011-02-01

Fish oils are one of the main sources of ω-3 fatty acids in animal and human diet. However, they can contain high concentrations of persistent organic pollutants due to their lipophilic properties. The aim of this study is the reduction of persistent organic pollutants in fish oil using silicon-based and carbon-based solid adsorbents. A wide screening study with different commercially available adsorbents was carried out, in order to determine their capacity of pollutant removal from fish oil. Moreover, adsorption conditions were evaluated and optimized with using an experimental design and adjustment of the experimental results to response surfaces, obtaining removals rates of more than 99% of PCDD/Fs, 81% of dioxin-like PCBs, 70% of HCB, 41% of DDTs, 16% of marker PCBs and 10% of PBDEs. Finally, fish oil fatty acids were analyzed before and after the treatment with solid adsorbents, confirming that it did not affect its nutritive properties. Copyright © 2010 Elsevier Ltd. All rights reserved.

Development of a computationally-designed polymeric adsorbent specific for mycotoxin patulin.

PubMed

Piletska, Elena V; Pink, Demi; Karim, Kal; Piletsky, Sergey A

2017-12-04

Patulin is a toxic compound which is found predominantly in apples affected by mould rot. Since apples and apple-containing products are a popular food for the elderly, children and babies, the monitoring of the toxin is crucial. This paper describes a development of a computationally-designed polymeric adsorbent for the solid-phase extraction of patulin, which provides an effective clean-up of the food samples and allows the detection and accurate quantification of patulin levels present in apple juice using conventional chromatography methods. The developed bespoke polymer demonstrates a quantitative binding towards the patulin present in undiluted apple juice. The polymer is inexpensive and easy to mass-produce. The contributing factors to the function of the adsorbent is a combination of acidic and basic functional monomers producing a zwitterionic complex in the solution that formed stronger binding complexes with the patulin molecule. The protocols described in this paper provide a blueprint for the development of polymeric adsorbents for other toxins or different food matrices.

How restrained eaters perceive the amount they eat.

PubMed

Jansen, A

1996-09-01

The cognitive model of binge eating states that it is the awareness of a broken diet that disinhibits the restrained eater. It is, according to that model, the perception of having overeaten that triggers disinhibited eating. However, although the perception of the amount eaten plays a central role in cognitive restraint theory, it has never directly been tested how restrained subjects perceive the amount of food they eat. In the present studies, participants were given ad libitum access to large amounts of palatable food and both their perception of the amount eaten and their estimated caloric intake were compared with the amount they actually ate. The restrained participants in these studies ate more than the unrestrained participants. In the first and second studies, the restrained participants consumed 571 and 372 'forbidden' calories respectively, without having the feeling that they had eaten very much, let alone too much. Moreover in both studies, the restrained eaters underestimated their caloric intake, whereas unrestrained eaters estimated their caloric intake quite well. The potential implications of the present findings for the cognitive restraint model are discussed.

Conformational changes of the amyloid beta-peptide (1-40) adsorbed on solid surfaces.

PubMed

Giacomelli, Carla E; Norde, Willem

2005-05-23

The conformational change of the 39-43 residues of the amyloid beta-peptide (Abeta) toward a beta-sheet enriched state promotes self-aggregation of the peptide molecules and constitutes the major peptide component of the amyloid plaques in Alzheimer patients. The crucial question behind the self-aggregation of Abeta is related to the different pathways the peptide may take after cleavage from the amyloid precursor proteins at cellular membranes. This work is aiming at determining the conformation of the Abeta (1-40) adsorbed on hydrophobic Teflon and hydrophilic silica particles, as model sorbent surfaces mimicking the apolar transmembrane environment and the polar, charged membrane surface, respectively. The mechanism by which the Abeta interacts with solid surfaces strongly depends on the hydrophobic/hydrophilic character of the particles. Hydrophobic and electrostatic interactions contribute differently in each case, causing a completely different conformational change of the adsorbed molecules on the two surfaces. When hydrophobic interactions between the peptide and the sorbent prevail, the adsorbed Abeta (1-40) mainly adopts an alpha-helix conformation due to H-bonding in the apolar part of the peptide that is oriented towards the surface. On the other hand, when the peptide adsorbs by electrostatic interactions beta-sheet formation is promoted due to intermolecular association between the apolar parts of the adsorbed peptide. Irrespective of the characteristics of the solid sorbent, crowding the surface results in intermolecular association between adsorbed molecules leading to a strong aggregation tendency of the Abeta (1-40). [Diagram: see text] CD spectra of Abeta (1-40) at pH 7: A) in solution ([Abeta]=0.2 mg.ml(-1)) freshly prepared (line) and after overnight incubation (symbols);B) on Teflon (Gamma=0.5 mg.m(-2)).

Influence of adsorbents in transdermal matrix patches on the release and the physical state of ethinyl estradiol and levonorgestrel.

PubMed

Schulz, Martin; Fussnegger, Bernhard; Bodmeier, Roland

2011-02-01

The drug release from medium molecular weight polyisobutene patches containing adsorbates (drug content: 0.2% ethinyl estradiol, 1.0% levonorgestrel; adsorbent content: 20%, w/w) increased in the order of no adsorbentadsorbent and the water uptake which increased in the order of no adsorbent (0.1%)=titanium dioxide (0.1%)adsorbates onto crospovidone were investigated in detail. Increasing the adsorbate's drug loading increased the drug release up to a crospovidone content of 15% (w/w). Patches were crystal free for crospovidone contents ≥ 10% (w/w), which corresponds to a drug loading of crospovidone of 12% (w/w). In conclusion, the incorporation of drug adsorbates onto crospovidone into patches based on polyisobutene significantly increased the drug release (approximately 9.1 times for ethinyl estradiol and 15.4 times for levonorgestrel) and prevented drug recrystallization. Copyright © 2010 Elsevier B.V. All rights reserved.

Influence of Current Velocity on Uranium Adsorption from Seawater Using an Amidoxime-based Polymer Fiber Adsorbent

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

Ladshaw, Austin; Kuo, Li-Jung; Strivens, Jonathan

2017-02-08

Passive adsorption using amidoxime-based polymeric adsorbents is being developed for uranium recovery from seawater. The local oceanic current velocity where the adsorbent is deployed is a key variable in determining locations that will maximize uranium adsorption rates. Two independent experimental approaches using flow-through columns and recirculating flumes were used to assess the influence of linear velocity on uranium uptake kinetics by the adsorbent. Little to no difference was observed in the uranium adsorption rate vs. linear velocity for seawater exposure in flow-through columns. In contrast, adsorption results from seawater exposure in a recirculating flume showed a nearly linear trend withmore » current velocity. The difference in adsorbent performance between columns and flume can be attributed to (i) flow resistance provided by the adsorbent braid in the flume and (ii) enhancement in braid movement (fluttering) with increasing linear velocity.« less

Influence of Current Velocity on Uranium Adsorption from Seawater Using an Amidoxime-Based Polymer Fiber Adsorbent

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

Ladshaw, Austin; Kuo, Li-Jung; Strivens, Jonathan

2017-02-17

Passive adsorption using amidoxime-based polymeric adsorbents is being developed for uranium recovery from seawater. The local oceanic current velocity where the adsorbent is deployed is a key variable in determining locations that will maximize uranium adsorption rates. Two independent experimental approaches using flow-through columns and recirculating flumes were used to assess the influence of linear velocity on uranium uptake kinetics by the adsorbent. Little to no difference was observed in the uranium adsorption rate vs. linear velocity for seawater exposure in flow-through columns. In contrast, adsorption results from seawater exposure in a recirculating flume showed a nearly linear trend withmore » current velocity. The difference in adsorbent performance between columns and flume can be attributed to (i) flow resistance provided by the adsorbent braid in the flume and (ii) enhancement in braid movement (fluttering) with increasing linear velocity.« less

Synthesis of Composite Adsorbent from Calcium Carbonate and Cocos Nucifera Carbon Powder Crosslinked with Biopolymer Matrix

NASA Astrophysics Data System (ADS)

Kamaruddin, M. A.; Bakri, M. M. A.; Norashiddin, F. A.; Zawawi, M. H.; Zainol, M. R. R. A.

2018-03-01

The use of coconut shell based adsorbent for removing various pollutants from wastewater offers attractive advantages such as exceptional adsorption capacity with larger surface area, low-cost and biocompatibility for a wide range of pollutants. The same goes for calcium carbonate based adsorbent, which provides better removal for metals ions through precipitation method. In fact, recycling of waste material is considered environmentally preferable and is supported by public opinion and government policy. However, because of unit operations mechanisms and effectiveness are different to one another in downstream process, it is quite difficult to provide good adsorbent that exhibits dual attributes of hydrophobic and hydrophilic characters. This paper provides brief process for sintering of composite adsorbent for separation and purification of industrial wastewater application. Characterization was performed by physical and chemical approach. Results prove that the inclusion of biopolymer as composite binder improved mechanical properties of the composite adsorbent.

Charge-transfer excited state in pyrene-1-carboxylic acids adsorbed on titanium dioxide nanoparticles

NASA Astrophysics Data System (ADS)

Krawczyk, S.; Nawrocka, A.; Zdyb, A.

2018-06-01

The electronic structure of excited photosensitizer adsorbed at the surface of a solid is the key factor in the electron transfer processes that underlie the efficiency of dye-sensitized solar cells and photocatalysts. In this work, Stark effect (electroabsorption) spectroscopy has been used to measure the polarizability and dipole moment changes in electronic transitions of pyrene-1-carboxylic (PCA), -acetic (PAA) and -butyric (PBA) acids in ethanol, both free and adsorbed on colloidal TiO2, in glassy ethanol at low temperature. The lack of appreciable increase of dipole moment in the excited state of free and adsorbed PAA and PBA points that two or more single bonds completely prevent the expansion of π-electrons from the aromatic ring towards the carboxylic group, thus excluding the possibility of direct electron injection into TiO2. In free PCA, the pyrene's forbidden S0 → S1 transition has increased intensity, exhibits a long progression in 1400 cm-1 Ag mode and is associated with |Δμ| of 2 D. Adsorption of PCA on TiO2 causes a broadening and red shift of the S0 → S1 absorption band and an increase in dipole moment change on electronic excitation to |Δμ| = 6.5 D. This value increased further to about 15 D when the content of acetic acid in the colloid was changed from 0.2% to 2%, and this effect is ascribed to the surface electric field. The large increase of |Δμ| points that the electric field effect can not only change the energetics of electron transfer from the excited sensitizer into the solid, but can also shift the molecular electronic density, thus directly influencing the electronic coupling factor relevant for electron transfer at the molecule-solid interface.

Sulfonated poly(ether ether ketone)/polypyrrole core-shell nanofibers: a novel polymeric adsorbent/conducting polymer nanostructures for ultrasensitive gas sensors.

PubMed

Wang, Wei; Li, Zhenyu; Jiang, Tingting; Zhao, Zhiwei; Li, Ye; Wang, Zhaojie; Wang, Ce

2012-11-01

Conducting polymers-based gas sensors have attracted increasing research attention these years. The introduction of inorganic sensitizers (noble metals or inorganic semiconductors) within the conducting polymers-based gas sensors has been regarded as the generally effective route for further enhanced sensors. Here we demonstrate a novel route for highly-efficient conducting polymers-based gas sensors by introduction of polymeric sensitizers (polymeric adsorbent) within the conducting polymeric nanostructures to form one-dimensional polymeric adsorbent/conducting polymer core-shell nanocomposites, via electrospinning and solution-phase polymerization. The adsorption effect of the SPEEK toward NH₃ can facilitate the mass diffusion of NH₃ through the PPy layers, resulting in the enhanced sensing signals. On the basis of the SPEEK/PPy nanofibers, the sensors exhibit large gas responses, even when exposed to very low concentration of NH₃ (20 ppb) at room temperature.

Temperature Dependence of Uranium and Vanadium Adsorption on Amidoxime-Based Adsorbents in Natural Seawater

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

Kuo, Li-Jung; Gill, Gary A.; Tsouris, Costas

Recent advances in the development of amidoxime-based adsorbents have made it highly promising for seawater uranium extraction. However, there is a great need to understand the influence of temperature on the uranium sequestration performance of the adsorbents in natural seawater. Here in this work, the apparent enthalpy and entropy of the sorption of uranium (VI) and vanadium (V) with amidoxime-based adsorbents were determined in natural seawater tests at 8, 20, and 31 °C that cover a broad range of ambient seawater temperature. The sorption of U was highly endothermic, producing apparent enthalpies of 57 ± 6.0 and 59 ± 11more » kJ mol -1 and apparent entropies of 314 ± 21 and 320 ± 36 J K-1 mol -1, respectively, for two adsorbent formulations. In contrast, the sorption of V showed a much smaller temperature sensitivity, producing apparent enthalpies of 6.1 ± 5.9 and -11 ± 5.7 kJ mol -1 and apparent entropies of 164 ± 20 and 103 ± 19 J K -1 mol -1, respectively. This new thermodynamic information suggests that amidoxime-based adsorbents will deliver significantly increased U adsorption capacities and improved selectivity in warmer waters. A separate field study of seawater uranium adsorption conducted in a warm seawater site (Miami, FL, USA) confirm the observed strong temperature effect on seawater uranium mining. Lastly, this strong temperature dependence demonstrates that the warmer the seawater where the amidoxime-based adsorbents are deployed the greater the yield for seawater uranium extraction.« less

Electronic structure studies of adsorbate-induced surface reconstructions: oxygen on Rh(1 0 0)

NASA Astrophysics Data System (ADS)

Kirsch, Janet E.; Harris, Suzanne

2004-03-01

Solid-state Fenske-Hall band structure calculations have been used to study the electronic structure and bonding that occur on an "asymmetric" clock reconstructed Rh(1 0 0) surface with a half-monolayer of O atom adsorbates. The displacement of the top-layer Rh atoms on reconstructed O/Rh(1 0 0) is similar to that observed when a half-monolayer of C or N atoms adsorb onto clean Ni(1 0 0). Unlike the five-coordinate C or N adsorbates that adsorb into effectively coplanar sites on the Ni(1 0 0) surface, however, O atoms sit well above the Rh surface plane and occupy three-coordinate adsorption sites. The results of these calculations show that the asymmetric clock reconstruction of O/Rh(1 0 0) increases the negative charge localized on the highly electronegative O atoms and strengthens the O-Rh bonding relative to an unreconstructed surface. This suggests that, in contrast to the C(N)/Ni(1 0 0) clock, which appears to be driven primarily by the restoration of metal-metal bonding, the asymmetric O/Rh(1 0 0) clock reconstruction is driven by the optimization of the O atom bonding environment. Comparisons of the O/Rh(1 0 0) and C(N, O)/Ni(1 0 0) surfaces further indicate that the electronegativity and electron count of the adsorbed species, as well as the electron count and physical size of the metal, all play a role in determining the preferred atomic geometries of these adsorbate-covered transition metal surfaces.

Temperature Dependence of Uranium and Vanadium Adsorption on Amidoxime-Based Adsorbents in Natural Seawater

DOE PAGES

Kuo, Li-Jung; Gill, Gary A.; Tsouris, Costas; ...

2018-01-16

Recent advances in the development of amidoxime-based adsorbents have made it highly promising for seawater uranium extraction. However, there is a great need to understand the influence of temperature on the uranium sequestration performance of the adsorbents in natural seawater. Here in this work, the apparent enthalpy and entropy of the sorption of uranium (VI) and vanadium (V) with amidoxime-based adsorbents were determined in natural seawater tests at 8, 20, and 31 °C that cover a broad range of ambient seawater temperature. The sorption of U was highly endothermic, producing apparent enthalpies of 57 ± 6.0 and 59 ± 11more » kJ mol -1 and apparent entropies of 314 ± 21 and 320 ± 36 J K-1 mol -1, respectively, for two adsorbent formulations. In contrast, the sorption of V showed a much smaller temperature sensitivity, producing apparent enthalpies of 6.1 ± 5.9 and -11 ± 5.7 kJ mol -1 and apparent entropies of 164 ± 20 and 103 ± 19 J K -1 mol -1, respectively. This new thermodynamic information suggests that amidoxime-based adsorbents will deliver significantly increased U adsorption capacities and improved selectivity in warmer waters. A separate field study of seawater uranium adsorption conducted in a warm seawater site (Miami, FL, USA) confirm the observed strong temperature effect on seawater uranium mining. Lastly, this strong temperature dependence demonstrates that the warmer the seawater where the amidoxime-based adsorbents are deployed the greater the yield for seawater uranium extraction.« less

The application of reused powdered wastes as adsorbent for treating arsenic containing mine drainage.

PubMed

Park, Youn-Jong; Yang, Jae-Kyu; Choi, Sang-Il

2008-07-15

This study examined the potential reuse of powdered wastes (PW) generated during the sanding and sawing process in a local chemical company in Korea with the viewpoint of the recycling these wastes and minimizing the level of contamination. The PW contained 40-60% aluminum hydroxide and 30-45% matrix resin. As a potential adsorbent, the suitability of thermal treated PW to remove arsenic from synthetic and real wastewater was investigated. As a pretreatment process, the reused adsorbent from PW was calcined at 550 degrees C for 3 hrs in a furnace. The calcination characteristics of PW were examined both quantitatively and qualitatively by X-ray fluorescence (XRF), and qualitatively by X-ray diffraction (XRD). The major inorganic composition of the calcined PW (CPW) was aluminum oxide with poor crystallinity. The CPW contained well developed meso-pores (0.143 cm(3) g(-1)) and showed a specific surface area of 234 m(2) g(-1). The pH of the zero point charge (pH(pzc)) of the CPW was determined to be 7.8 by acid-base titration. From the batch adsorption tests, the complete removal of arsenic (up to 20 mg L(-1)) was observed with CPW (2 g) at pH ranging from 3.0 to 8.0. However, there was a significant decrease in arsenate adsorption at higher pH. A kinetics study indicated that the uptake of arsenate followed a second-order rate equation. In the presence of sulfate, the removal of arsenate was increasingly affected by the sulfate concentration. The application of CPW to the removal of 4 different real mine drainages was also carried out. Mine drainage contains a relatively high arsenate concentration as well as sulfate. Whilst the amount of arsenic removed from real mine drainage by CPW was slightly lower than that removed from synthetic wastewater due to competitive sorption by multiple ions, the adsorption of arsenate showed rapid removal within 10 min with good removal efficiency, which meets the national wastewater discharge limits. These results suggest that CPW

Highly selective and efficient removal of lead with magnetic nano-adsorbent: Multivariate optimization, isotherm and thermodynamic studies.

PubMed

Khani, Rouhollah; Sobhani, Sara; Beyki, Mostafa Hossein

2016-03-15

2-Hydroxyethylammonium sulfonate immobilized on γ-Fe2O3 nanoparticles (γ-Fe2O3-2-HEAS) was synthesized by the reaction of n-butylsulfonated γ-Fe2O3 with ethanolamine. The structure of the resulting product was confirmed by fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD) spectrometry, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), elemental analysis, N2 adsorption-desorption and vibrating sample magnetometer (VSM) techniques. The supported ionic liquid on γ-Fe2O3 was applied as a new and green adsorbent to remove Pb(II) from aqueous solution. The effect of adsorption parameters such as pH, shaking time and amount of the adsorbent were investigated using two level three factor (2(3)) full factorial central composite design with the help of Design-Expert, Stat-Ease Inc. version 9.0 software. The significance of independent variables and their interactions were tested by means of the analysis of variance (ANOVA) with 95% confidence limits (α=0.05). The thermodynamic parameters of the adsorption process are estimated. It is found that the process is exothermic and spontaneous. The Langmuir and Freundlich models have been also applied to evaluate the removal efficiency and the data were correlated well with the Freundlich model. Copyright © 2015 Elsevier Inc. All rights reserved.

Amine-tethered solid adsorbents coupling high adsorption capacity and regenerability for CO2 capture from ambient air.

PubMed

Choi, Sunho; Gray, McMahan L; Jones, Christopher W

2011-05-23

Silica supported poly(ethyleneimine) (PEI) materials are prepared via impregnation and demonstrated to be promising adsorbents for CO(2) capture from ultra-dilute gas streams such as ambient air. A prototypical class 1 adsorbent, containing 45 wt% PEI (PEI/silica), and two new modified PEI-based aminosilica adsorbents, derived from PEI modified with 3-aminopropyltrimethoxysilane (A-PEI/silica) or tetraethyl orthotitanate (T-PEI/silica), are prepared and characterized by using thermogravimetric analysis and FTIR spectroscopy. The modifiers are shown to enhance the thermal stability of the polymer-oxide composites, leading to higher PEI decomposition temperatures. The modified adsorbents present extremely high CO(2) adsorption capacities under conditions simulating ambient air (400 ppm CO(2) in inert gas), exceeding 2 mol(CO (2)) kg(sorbent)(-1), as well as enhanced adsorption kinetics compared to conventional class 1 sorbents. The new adsorbents show excellent stability in cyclic adsorption-desorption operations, even under dry conditions in which aminosilica adsorbents are known to lose capacity due to urea formation. Thus, the adsorbents of this type can be considered promising materials for the direct capture of CO(2) from ultra-dilute gas streams such as ambient air. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison Analysis among Large Amount of SNS Sites

NASA Astrophysics Data System (ADS)

Toriumi, Fujio; Yamamoto, Hitoshi; Suwa, Hirohiko; Okada, Isamu; Izumi, Kiyoshi; Hashimoto, Yasuhiro

In recent years, application of Social Networking Services (SNS) and Blogs are growing as new communication tools on the Internet. Several large-scale SNS sites are prospering; meanwhile, many sites with relatively small scale are offering services. Such small-scale SNSs realize small-group isolated type of communication while neither mixi nor MySpace can do that. However, the studies on SNS are almost about particular large-scale SNSs and cannot analyze whether their results apply for general features or for special characteristics on the SNSs. From the point of view of comparison analysis on SNS, comparison with just several types of those cannot reach a statistically significant level. We analyze many SNS sites with the aim of classifying them by using some approaches. Our paper classifies 50,000 sites for small-scale SNSs and gives their features from the points of network structure, patterns of communication, and growth rate of SNS. The result of analysis for network structure shows that many SNS sites have small-world attribute with short path lengths and high coefficients of their cluster. Distribution of degrees of the SNS sites is close to power law. This result indicates the small-scale SNS sites raise the percentage of users with many friends than mixi. According to the analysis of their coefficients of assortativity, those SNS sites have negative values of assortativity, and that means users with high degree tend to connect users with small degree. Next, we analyze the patterns of user communication. A friend network of SNS is explicit while users' communication behaviors are defined as an implicit network. What kind of relationships do these networks have? To address this question, we obtain some characteristics of users' communication structure and activation patterns of users on the SNS sites. By using new indexes, friend aggregation rate and friend coverage rate, we show that SNS sites with high value of friend coverage rate activate diary postings

Evaluation of Toluene Adsorption Performance of Mortar Adhesives Using Porous Carbon Material as Adsorbent.

PubMed

Wi, Seunghwan; Chang, Seong Jin; Jeong, Su-Gwang; Lee, Jongki; Kim, Taeyeon; Park, Kyung-Won; Lee, Dong Ryeol; Kim, Sumin

2017-07-26

Porous carbon materials are advantageous in adsorbing pollutants due to their wide range of specific surface areas, pore diameter, and pore volume. Among the porous carbon materials in the current study, expanded graphite, xGnP, xGnP C-300, xGnP C-500, and xGnP C-750 were prepared as adsorbent materials. Brunauer-Emmett-Teller (BET) analysis was conducted to select the adsorbent material through the analysis of the specific surface area, pore size, and pore volume of the prepared porous carbon materials. Morphological analysis using SEM was also performed. The xGnP C-500 as adsorbent material was applied to a mortar adhesive that is widely used in the installation of interior building materials. The toluene adsorption performances of the specimens were evaluated using 20 L small chamber. Furthermore, the performance of the mortar adhesive, as indicated by the shear bond strength, length change rate, and water retention rate, was analyzed according to the required test method specified in the Korean standards. It was confirmed that for the mortar adhesives prepared using the xGnP C-500 as adsorbent material, the toluene adsorption performance was excellent and satisfied the required physical properties.

Evaluation of Toluene Adsorption Performance of Mortar Adhesives Using Porous Carbon Material as Adsorbent

PubMed Central

Chang, Seong Jin; Jeong, Su-Gwang; Lee, Jongki; Kim, Taeyeon; Park, Kyung-Won; Lee, Dong Ryeol; Kim, Sumin

2017-01-01

Porous carbon materials are advantageous in adsorbing pollutants due to their wide range of specific surface areas, pore diameter, and pore volume. Among the porous carbon materials in the current study, expanded graphite, xGnP, xGnP C-300, xGnP C-500, and xGnP C-750 were prepared as adsorbent materials. Brunauer–Emmett–Teller (BET) analysis was conducted to select the adsorbent material through the analysis of the specific surface area, pore size, and pore volume of the prepared porous carbon materials. Morphological analysis using SEM was also performed. The xGnP C-500 as adsorbent material was applied to a mortar adhesive that is widely used in the installation of interior building materials. The toluene adsorption performances of the specimens were evaluated using 20 L small chamber. Furthermore, the performance of the mortar adhesive, as indicated by the shear bond strength, length change rate, and water retention rate, was analyzed according to the required test method specified in the Korean standards. It was confirmed that for the mortar adhesives prepared using the xGnP C-500 as adsorbent material, the toluene adsorption performance was excellent and satisfied the required physical properties. PMID:28773214

Radiolysis of alanine adsorbed in a clay mineral

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

Aguilar-Ovando, Ellen Y.; Negron-Mendoza, Alicia

2013-07-03

Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role againstmore » external sources of ionizing radiation (specifically {gamma}-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine.« less

Physico-chemical properties of biodiesel manufactured from waste frying oil using domestic adsorbents

PubMed Central

Ismail, Samir Abd-elmonem A; Ali, Rehab Farouk M

2015-01-01

We have evaluated the efficiency of sugar cane bagasse ash (SCBA), date palm seed carbon (DPSC), and rice husk ash (RHA) as natural adsorbents and compared them with the synthetic adsorbent Magnesol XL for improving the quality of waste frying oil (WFO) and for the impact on the physicochemical properties of the obtained biodiesel. We measured moisture content, refractive index (RI), density, acid value (AV), iodine value (IV), peroxide value (PV), and saponification value (SV), as well as fatty acid profile. Purification treatments with various levels of adsorbents caused significant (P ≤ 0.05) decreases in free fatty acids (FFAs), PVs, and IVs. The highest yields (86.45 and 87.80%) were observed for biodiesel samples produced from WFO treated with 2% Magnesol and 3% of RHA, respectively, followed by samples treated with 2 and 3% of DPSC or RHA. Pre-treatments caused a significant decrease in the content of C 18:2 linoleic acids, consistent with a significant increase in the content of monounsaturated and saturated fatty acids (MUFA) in the treated samples. The highest oxidation value (COX) (1.30) was observed for biodiesel samples produced from WFO without purification treatments. However, the lowest values (0.44–0.73) were observed for biodiesel samples produced from WFO treated with different levels of adsorbents. Our results indicate that pre-treatments with different levels of adsorbents regenerated the quality of WFO and improved the quality of the obtained biodiesel. PMID:27877789

Physico-chemical properties of biodiesel manufactured from waste frying oil using domestic adsorbents

NASA Astrophysics Data System (ADS)

Ismail, Samir Abd-elmonem A.; Ali, Rehab Farouk M.

2015-06-01

We have evaluated the efficiency of sugar cane bagasse ash (SCBA), date palm seed carbon (DPSC), and rice husk ash (RHA) as natural adsorbents and compared them with the synthetic adsorbent Magnesol XL for improving the quality of waste frying oil (WFO) and for the impact on the physicochemical properties of the obtained biodiesel. We measured moisture content, refractive index (RI), density, acid value (AV), iodine value (IV), peroxide value (PV), and saponification value (SV), as well as fatty acid profile. Purification treatments with various levels of adsorbents caused significant (P ≤ 0.05) decreases in free fatty acids (FFAs), PVs, and IVs. The highest yields (86.45 and 87.80%) were observed for biodiesel samples produced from WFO treated with 2% Magnesol and 3% of RHA, respectively, followed by samples treated with 2 and 3% of DPSC or RHA. Pre-treatments caused a significant decrease in the content of C 18:2 linoleic acids, consistent with a significant increase in the content of monounsaturated and saturated fatty acids (MUFA) in the treated samples. The highest oxidation value (COX) (1.30) was observed for biodiesel samples produced from WFO without purification treatments. However, the lowest values (0.44-0.73) were observed for biodiesel samples produced from WFO treated with different levels of adsorbents. Our results indicate that pre-treatments with different levels of adsorbents regenerated the quality of WFO and improved the quality of the obtained biodiesel.

Type of adsorbent and column height in adsorption process of used cooking oil

NASA Astrophysics Data System (ADS)

Hasnelly, Hervelly, Taufik, Yusman; Melany, Ivo Nila

2015-12-01

The purpose of this research was to find out the best adsorbent and column height that can adsorb color and soluble impurities substances in used cooking oil. This research was meant for knowledge development of refined cooking oil technology. The used of this research was giving out information on the recycling process of used cooking oil. Research design used 2 × 2 factorial pattern in randomized group design with 6 repetitions. The first factor is adsorbent type (J) that consist of activated carbon (J1) and Zeolit (J2). The second factor is column height (K) with variations of 15 cm (k1) and 20 cm (k2). Chemical analysis parameter are free fatty acid, water content and saponification value. Physical parameter measurement was done on color with Hunter Lab system analysis and viscosity using viscometer method. Chemical analysis result of preliminary research on used cooking oil showed water content of 1,9%, free fatty acid 1,58%, saponification value 130,79 mg KOH/g oil, viscosity 0,6 d Pas and color with L value of -27,60, a value 1,04 and b value 1,54. Result on main research showed that adsorbent type only gave effect on water content whereas column height and its interaction was not gave significant effect on water content. Interaction between adsorbent type (J) and column height (K) gave significant effect to free fatty acid, saponification value, viscosity and color for L, a and b value of recycled cooking oil.

9 CFR 381.412 - Reference amounts customarily consumed per eating occasion.

Code of Federal Regulations, 2013 CFR

2013-01-01

... appropriate national food consumption surveys. (2) The Reference Amounts are calculated for an infant or child... are based on data set forth in appropriate national food consumption surveys. Such Reference Amounts... child under 4 years of age. (3) An appropriate national food consumption survey includes a large sample...

9 CFR 381.412 - Reference amounts customarily consumed per eating occasion.

Code of Federal Regulations, 2012 CFR

2012-01-01

... appropriate national food consumption surveys. (2) The Reference Amounts are calculated for an infant or child... are based on data set forth in appropriate national food consumption surveys. Such Reference Amounts... child under 4 years of age. (3) An appropriate national food consumption survey includes a large sample...

9 CFR 317.312 - Reference amounts customarily consumed per eating occasion.

Code of Federal Regulations, 2013 CFR

2013-01-01

... appropriate national food consumption surveys. (2) The Reference Amounts are calculated for an infant or child... are based on data set forth in appropriate national food consumption surveys. Such Reference Amounts... child under 4 years of age. (3) An appropriate national food consumption survey includes a large sample...

9 CFR 317.312 - Reference amounts customarily consumed per eating occasion.

Code of Federal Regulations, 2014 CFR

2014-01-01

... appropriate national food consumption surveys. (2) The Reference Amounts are calculated for an infant or child... are based on data set forth in appropriate national food consumption surveys. Such Reference Amounts... child under 4 years of age. (3) An appropriate national food consumption survey includes a large sample...

9 CFR 381.412 - Reference amounts customarily consumed per eating occasion.

Code of Federal Regulations, 2014 CFR

2014-01-01

... appropriate national food consumption surveys. (2) The Reference Amounts are calculated for an infant or child... are based on data set forth in appropriate national food consumption surveys. Such Reference Amounts... child under 4 years of age. (3) An appropriate national food consumption survey includes a large sample...

9 CFR 317.312 - Reference amounts customarily consumed per eating occasion.

Code of Federal Regulations, 2012 CFR

2012-01-01

... appropriate national food consumption surveys. (2) The Reference Amounts are calculated for an infant or child... are based on data set forth in appropriate national food consumption surveys. Such Reference Amounts... child under 4 years of age. (3) An appropriate national food consumption survey includes a large sample...

Fate of Adsorbed U(VI) during Sulfidization of Lepidocrocite and Hematite

PubMed Central

2017-01-01

The impact on U(VI) adsorbed to lepidocrocite (γ-FeOOH) and hematite (α-Fe2O3) was assessed when exposed to aqueous sulfide (S(-II)aq) at pH 8.0. With both minerals, competition between S(-II) and U(VI) for surface sites caused instantaneous release of adsorbed U(VI). Compared to lepidocrocite, consumption of S(-II)aq proceeded slower with hematite, but yielded maximum dissolved U concentrations that were more than 10 times higher, representing about one-third of the initially adsorbed U. Prolonged presence of S(-II)aq in experiments with hematite in combination with a larger release of adsorbed U(VI), enhanced the reduction of U(VI): after 24 h of reaction about 60–70% of U was in the form of U(IV), much higher than the 25% detected in the lepidocrocite suspensions. X-ray absorption spectra indicated that U(IV) in both hematite and lepidocrocite suspensions was not in the form of uraninite (UO2). Upon exposure to oxygen only part of U(IV) reoxidized, suggesting that monomeric U(IV) might have become incorporated in newly formed iron precipitates. Hence, sulfidization of Fe oxides can have diverse consequences for U mobility: in short-term, desorption of U(VI) increases U mobility, while reduction to U(IV) and its possible incorporation in Fe transformation products may lead to long-term U immobilization. PMID:28121137

Large Amounts of Reactivated Virus in Tears Precedes Recurrent Herpes Stromal Keratitis in Stressed Rabbits Latently Infected with Herpes Simplex Virus.

PubMed

Perng, Guey-Chuen; Osorio, Nelson; Jiang, Xianzhi; Geertsema, Roger; Hsiang, Chinhui; Brown, Don; BenMohamed, Lbachir; Wechsler, Steven L

2016-01-01

Recurrent herpetic stromal keratitis (rHSK), due to an immune response to reactivation of herpes simplex virus (HSV-1), can cause corneal blindness. The development of therapeutic interventions such as drugs and vaccines to decrease rHSK have been hampered by the lack of a small and reliable animal model in which rHSK occurs at a high frequency during HSV-1 latency. The aim of this study is to develop a rabbit model of rHSK in which stress from elevated temperatures increases the frequency of HSV-1 reactivations and rHSK. Rabbits latently infected with HSV-1 were subjected to elevated temperatures and the frequency of viral reactivations and rHSK were determined. In an experiment in which rabbits latently infected with HSV-1 were subjected to ill-defined stress as a result of failure of the vivarium air conditioning system, reactivation of HSV-1 occurred at over twice the normal frequency. In addition, 60% of eyes developed severe rHSK compared to <1% of eyes normally. All episodes of rHSK were preceded four to five days prior by an unusually large amount of reactivated virus in the tears of that eye and whenever this unusually large amount of reactivated virus was detected in tears, rHSK always appeared 4-5 days later. In subsequent experiments using well defined heat stress the reactivation frequency was similarly increased, but no eyes developed rHSK. The results reported here support the hypothesis that rHSK is associated not simply with elevated reactivation frequency, but rather with rare episodes of very high levels of reactivated virus in tears 4-5 days earlier.

Screening of metal-organic frameworks for carbon dioxide capture from flue gas using a combined experimental and modeling approach.

PubMed

Yazaydin, A Ozgür; Snurr, Randall Q; Park, Tae-Hong; Koh, Kyoungmoo; Liu, Jian; Levan, M Douglas; Benin, Annabelle I; Jakubczak, Paulina; Lanuza, Mary; Galloway, Douglas B; Low, John J; Willis, Richard R

2009-12-30

A diverse collection of 14 metal-organic frameworks (MOFs) was screened for CO(2) capture from flue gas using a combined experimental and modeling approach. Adsorption measurements are reported for the screened MOFs at room temperature up to 1 bar. These data are used to validate a generalized strategy for molecular modeling of CO(2) and other small molecules in MOFs. MOFs possessing a high density of open metal sites are found to adsorb significant amounts of CO(2) even at low pressure. An excellent correlation is found between the heat of adsorption and the amount of CO(2) adsorbed below 1 bar. Molecular modeling can aid in selection of adsorbents for CO(2) capture from flue gas by screening a large number of MOFs.

Adsorbate-induced lifting of substrate relaxation is a general mechanism governing titania surface chemistry.

PubMed

Silber, David; Kowalski, Piotr M; Traeger, Franziska; Buchholz, Maria; Bebensee, Fabian; Meyer, Bernd; Wöll, Christof

2016-09-30

Under ambient conditions, almost all metals are coated by an oxide. These coatings, the result of a chemical reaction, are not passive. Many of them bind, activate and modify adsorbed molecules, processes that are exploited, for example, in heterogeneous catalysis and photochemistry. Here we report an effect of general importance that governs the bonding, structure formation and dissociation of molecules on oxidic substrates. For a specific example, methanol adsorbed on the rutile TiO 2 (110) single crystal surface, we demonstrate by using a combination of experimental and theoretical techniques that strongly bonding adsorbates can lift surface relaxations beyond their adsorption site, which leads to a significant substrate-mediated interaction between adsorbates. The result is a complex superstructure consisting of pairs of methanol molecules and unoccupied adsorption sites. Infrared spectroscopy reveals that the paired methanol molecules remain intact and do not deprotonate on the defect-free terraces of the rutile TiO 2 (110) surface.

Adsorbate-induced lifting of substrate relaxation is a general mechanism governing titania surface chemistry

NASA Astrophysics Data System (ADS)

Silber, David; Kowalski, Piotr M.; Traeger, Franziska; Buchholz, Maria; Bebensee, Fabian; Meyer, Bernd; Wöll, Christof

2016-09-01

Under ambient conditions, almost all metals are coated by an oxide. These coatings, the result of a chemical reaction, are not passive. Many of them bind, activate and modify adsorbed molecules, processes that are exploited, for example, in heterogeneous catalysis and photochemistry. Here we report an effect of general importance that governs the bonding, structure formation and dissociation of molecules on oxidic substrates. For a specific example, methanol adsorbed on the rutile TiO2(110) single crystal surface, we demonstrate by using a combination of experimental and theoretical techniques that strongly bonding adsorbates can lift surface relaxations beyond their adsorption site, which leads to a significant substrate-mediated interaction between adsorbates. The result is a complex superstructure consisting of pairs of methanol molecules and unoccupied adsorption sites. Infrared spectroscopy reveals that the paired methanol molecules remain intact and do not deprotonate on the defect-free terraces of the rutile TiO2(110) surface.

Adsorption and Desorption of Carbon Dioxide and Water Mixtures on Synthetic Hydrophobic Carbonaceous Adsorbents

NASA Technical Reports Server (NTRS)

Finn, John E.; Harper, Lynn D. (Technical Monitor)

1994-01-01

Several synthetic carbonaceous adsorbents produced through pyrolysis of polymeric materials are available commercially. Some appear to have advantages over activated carbon for certain adsorption applications. In particular, they can have tailored hydrophobicities that are significantly greater than that of activated carbon, while moderately high surfaces areas are retained. These sorbents are being investigated for possible use in removing trace contaminants and excess carbon dioxide from air in closed habitats, plant growth chambers, and other applications involving purification of humid gas streams. We have analyzed the characteristics of a few of these adsorbents through adsorption and desorption experiments and standard characterization techniques. This paper presents pure and multicomponent adsorption data collected for carbon dioxide and water on two synthetic carbonaceous adsorbents having different hydrophobicities and capillary condensation characteristics. The observations are interpreted through consideration of the pore structure and surface chemistry of the solids and interactions between adsorbed carbon dioxide, water, and the solvent gas.

Exciton Splitting of Adsorbed and Free 4-Nitroazobenzene Dimers: A Quantum Chemical Study.

PubMed

Titov, Evgenii; Saalfrank, Peter

2016-05-19

Molecular photoswitches such as azobenzenes, which undergo photochemical trans ↔ cis isomerizations, are often mounted for possible applications on a surface and/or surrounded by other switches, for example, in self-assembled monolayers. This may suppress the isomerization cross section due to possible steric reasons, or, as recently speculated, by exciton coupling to neighboring switches, leading to ultrafast electronic quenching (Gahl et al., J. Am. Chem. Soc. 2010, 132, 1831). The presence of exciton coupling has been anticipated from a blue shift of the optical absorption band, compared to molecules in solution. From the theory side the need arises to properly analyze and quantify the change of absorption spectra of interacting and adsorbed switches. In particular, suitable methods should be identified, and effects of intermolecule and molecule-surface interactions on spectra should be disentangled. In this paper by means of time-dependent Hartree-Fock (TD-HF), various flavors of time-dependent density functional theory (TD-DFT), and the correlated wave function based coupled-cluster (CC2) method we investigated the 4-nitroazobenzene molecule as an example: The low-lying singlet excited states in the isolated trans monomer and dimer as well as their composites with a silicon pentamantane nanocluster, which serves also as a crude model for a silicon surface, were determined. As most important results we found that (i) HF, CC2, range-separated density functionals, or global hybrids with large amount of exact exchange are able to describe exciton (Davydov) splitting properly, while hybrids with small amount of exact exchange fail producing spurious charge transfer. (ii) The exciton splitting in a free dimer would lead to a blue shift of the absorption signal; however, this effect is almost nullified or even overcompensated by the shift arising from van der Waals interactions between the two molecules. (iii) Adsorption on the Si "surface" leads to a further

Magnetic hydroxyapatite nanoparticles: an efficient adsorbent for the separation and removal of nitrate and nitrite ions from environmental samples.

PubMed

Ghasemi, Ensieh; Sillanpää, Mika

2015-01-01

A novel type of magnetic nanosorbent, hydroxyapatite-coated Fe2O3 nanoparticles was synthesized and used for the adsorption and removal of nitrite and nitrate ions from environmental samples. The properties of synthesized magnetic nanoparticles were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray powder diffraction. After the adsorption process, the separation of γ-Fe2O3@hydroxyapatite nanoparticles from the aqueous solution was simply achieved by applying an external magnetic field. The effects of different variables on the adsorption efficiency were studied simultaneously using an experimental design. The variables of interest were amount of magnetic hydroxyapatite nanoparticles, sample volume, pH, stirring rate, adsorption time, and temperature. The experimental parameters were optimized using a Box-Behnken design and response surface methodology after a Plackett-Burman screening design. Under the optimum conditions, the adsorption efficiencies of magnetic hydroxyapatite nanoparticles adsorbents toward NO3(-) and NO2(-) ions (100 mg/L) were in the range of 93-101%. The results revealed that the magnetic hydroxyapatite nanoparticles adsorbent could be used as a simple, efficient, and cost-effective material for the removal of nitrate and nitrite ions from environmental water and soil samples. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Elimination of As(V) by bead cellulose adsorbent loaded with Fe (beta-FeOOH) from groundwater].

PubMed

Guo, Xue-jun; Chen, Fu-hua

2005-05-01

A new adsorbent, bead cellulose impregnated with Fe oxide hydroxide (beta-FeOOH) was prepared, which is porous and has excellent mechanical properties. The content of iron, the reactive center of the adsorbent was 360 mg/mL at the most (50% in mass). Batch sorption experiments show that the adsorbent had 15.6 mg/mL (33.2 mg/g) of As(V) maximum sorption while the iron content was 220 mg/mL. The adsorbent had good kinetic property for arsenate and the adsorption equilibrium reached in 10 h. The sorption kinetic data can be described by Lagergren pseudo-second order rate equation. The addition of chloride, sulfate and silicate did not affecte the arsenic adsorption. The column experiment indicated that the breakthrough bed volume was 5000 BV while influent As(V) concentration was 500 microg/L and empty contact time was 5.9 min. The spent adsorbent can be regenerated eluting with 1.5 mol x L(-1) NaOH solutions, and the desorption and regeneration process were more than 90%. The FeOOH was chemically stable during the column adsorption and regeneration. The preparation method is simple and innovative. The adsorbent has good future applying for the arsenic removal from groundwater and drinking water.

Development of the protocol for purification of artemisinin based on combination of commercial and computationally designed adsorbents.

PubMed

Piletska, Elena V; Karim, Kal; Cutler, Malcolm; Piletsky, Sergey A

2013-01-01

A polymeric adsorbent for extraction of the antimalarial drug artemisinin from Artemisia annua L. was computationally designed. This polymer demonstrated a high capacity for artemisinin (120 mg g(-1) ), quantitative recovery (87%) and was found to be an effective material for purification of artemisinin from complex plant matrix. The artemisinin quantification was conducted using an optimised HPLC-MS protocol, which was characterised by high precision and linearity in the concentration range between 0.05 and 2 μg mL(-1) . Optimisation of the purification protocol also involved screening of commercial adsorbents for the removal of waxes and other interfering natural compounds, which inhibit the crystallisation of artemisinin. As a result of a two step-purification protocol crystals of artemisinin were obtained, and artemisinin purity was evaluated as 75%. By performing the second stage of purification twice, the purity of artemisinin can be further improved to 99%. The developed protocol produced high-purity artemisinin using only a few purification steps that makes it suitable for large scale industrial manufacturing process. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High background in Luminex® assay for HLA antibody screening: Interest of Adsorb Out™.

PubMed

Zerrouki, Asmae; Ouadghiri, Sanae; Benseffaj, Nadia; Razine, Rachid; Essakalli, Malika

2016-05-01

The Luminex® technology has become an integral component of clinical decision-making and diagnosis of transplanted organ rejection. Despite the superior sensibility of this technology, it is not completely problem free. We have observed in these bead-based assays that sera of some patients give a high negative control bead (NC) value which makes assessing HLA antibodies difficult. Treatment of sera by the Adsorb Out™ reagent may reduce the high background. In this study, we want to evaluate the effect of the Adsorb Out™ on the NC's MFI value by comparing treated and untreated patients' sera. HLA antibody screening was performed on 3011 sera. These sera came from patients awaiting and undergoing renal transplant from different Moroccan hospitals. The sera were analyzed using the standard protocol for Luminex® antibody screening. Sera with high NC's value has been pre-incubated by the Adsorb Out™, and analyzed on Luminex®. 3% of studied samples have high NC's value. The Adsorb Out™ decreases the NC's value and brings it back to a normal range in 62.2% treated sera. It has no effect in 12.3%. The Adsorb Out™ effect depends only of NC's value, independently to age, storage date, sex and immunization. The Adsorb Out™ reagent has an important effect in decreasing NC value of sera. However, it has no effect in some patient's sera. In these cases we could try another treatment, as EDTA, DTT. The non-specific binding may be caused by multiple patient-specific factors, it would be important to search correlation between them and NC's values. Copyright © 2016 Elsevier B.V. All rights reserved.

Atmospheric fate of oil matter adsorbed on sea salt particles under UV light

NASA Astrophysics Data System (ADS)

Vaitilingom, M.; Avij, P.; Huang, H.; Valsaraj, K. T.

2014-12-01

The presence of liquid petroleum hydrocarbons at the sea water surface is an important source of marine pollution. An oil spill in sea-water will most likely occur due to an involuntary accident from tankers, offshore platforms, etc. However, a large amount of oil is also deliberately spilled in sea-water during the clean-out process of tank vessels (e.g. for the Mediterranean Sea, 490,000 tons/yr). Moreover, the pollution caused by an oil spill does not only affect the aquatic environment but also is of concern for the atmospheric environment. A portion of the oil matter present at the sea-water surface is transported into the atmosphere viaevaporation and adsorption at the surface of sea spray particles. Few studies are related to the presence of oil matter in airborne particles resulting from their adsorption on sea salt aerosols. We observed that the non-volatile oil matter was adsorbed at the surface of sea-salt crystals (av. size of 1.1 μm). Due to their small size, these particles can have a significant residence time in the atmosphere. The hydrocarbon matter adsorbed at the surface of these particles can also be transformed by catalyzers present in the atmosphere (i.e. UV, OH, O3, ...). In this work, we focused on the photo-oxidation rates of the C16 to C30alkanes present in these particles. We utilized a bubble column reactor, which produced an abundance of small sized bubbles. These bubbles generated droplets upon bursting at the air-salt water interface. These droplets were then further dried up and lifted to the top of the column where they were collected as particles. These particles were incubated in a controlled reactor in either dark conditions or under UV-visible light. The difference of alkane content analyzed by GC-MS between the particles exposed to UV or the particles not exposed to UV indicated that up to 20% in mass was lost after 20 min of light exposure. The degradation kinetics varied for each range of alkanes (C16-20, C21-25, C26

Prussian blue caged in spongiform adsorbents using diatomite and carbon nanotubes for elimination of cesium.

PubMed

Hu, Baiyang; Fugetsu, Bunshi; Yu, Hongwen; Abe, Yoshiteru

2012-05-30

We developed a spongiform adsorbent that contains Prussian blue, which showed a high capacity for eliminating cesium. An in situ synthesizing approach was used to synthesize Prussian blue inside diatomite cavities. Highly dispersed carbon nanotubes (CNTs) were used to form CNT networks that coated the diatomite to seal in the Prussian blue particles. These ternary (CNT/diatomite/Prussian-blue) composites were mixed with polyurethane (PU) prepolymers to produce a quaternary (PU/CNT/diatomite/Prussian-blue), spongiform adsorbent with an in situ foaming procedure. Prussian blue was permanently immobilized in the cell walls of the spongiform matrix and preferentially adsorbed cesium with a theoretical capacity of 167 mg/g cesium. Cesium was absorbed primarily by an ion-exchange mechanism, and the absorption was accomplished by self-uptake of radioactive water by the quaternary spongiform adsorbent. Copyright © 2012 Elsevier B.V. All rights reserved.

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.

First-principles configurational thermodynamics of alloyed nanoparticles with adsorbates

NASA Astrophysics Data System (ADS)

Wang, Lin-Lin; Tan, Teck L.; Johnson, Duane D.

2014-03-01

Transition-metal, alloyed nanoparticles (NPs) are key components in current and emerging energy technologies because they are found to improve catalytic activity and selectivity for many energy-conversion processes. However, thermodynamic investigations of the compositional profile of alloyed nanoparticles, which determines their catalytic properties, have been limited mostly to NP core-shell preference without the presence of adsorbates. Here, by extending cluster expansion methods to treat both alloyed nanoparticles and adsorbates, we study the configurational thermodynamics of bimetallic NPs under chemically reactive conditions, using databases from density functional theory calculations. With a few examples, we show that such simulations can provide information needed for rational design of NP catalysts. DOE/BES under DE-FG02-03ER15476 (Catalysis) and DE-AC02-07CH11358 at the Ames Laboratory.

XPS and bioactivity study of the bisphosphonate pamidronate adsorbed onto plasma sprayed hydroxyapatite coatings

NASA Astrophysics Data System (ADS)

McLeod, Kate; Kumar, Sunil; Smart, Roger St. C.; Dutta, Naba; Voelcker, Nicolas H.; Anderson, Gail I.; Sekel, Ron

2006-12-01

This paper reports the use of X-ray photoelectron spectroscopy (XPS) to investigate bisphosphonate (BP) adsorption onto plasma sprayed hydroxyapatite (HA) coatings commonly used for orthopaedic implants. BPs exhibit high binding affinity for the calcium present in HA and hence can be adsorbed onto HA-coated implants to exploit their beneficial properties for improved bone growth at the implant interface. A rigorous XPS analysis of pamidronate, a commonly used nitrogenous BP, adsorbed onto plasma sprayed HA-coated cobalt-chromium substrates has been carried out, aimed at: (a) confirming the adsorption of this BP onto HA; (b) studying the BP diffusion profile in the HA coating by employing the technique of XPS depth profiling; (c) confirming the bioactivity of the adsorbed BP. XPS spectra of plasma sprayed HA-coated discs exposed to a 10 mM aqueous BP solution (pamidronate) for periods of 1, 2 and 24 h showed nitrogen and phosphorous photoelectron signals corresponding to the BP, confirming its adsorption onto the HA substrate. XPS depth profiling of the 2 h BP-exposed HA discs showed penetration of the BP into the HA matrix to depths of at least 260 nm. The bioactivity of the adsorbed BP was confirmed by the observed inhibition of osteoclast (bone resorbing) cell activity. In comparison to the HA sample, the HA sample with adsorbed BP exhibited a 25-fold decrease in primary osteoclast cells.

Generalized scaling relationships on transition metals: Influence of adsorbate-coadsorbate interactions

NASA Astrophysics Data System (ADS)

Majumdar, Paulami; Greeley, Jeffrey

2018-04-01

Linear scaling relations of adsorbate energies across a range of catalytic surfaces have emerged as a central interpretive paradigm in heterogeneous catalysis. They are, however, typically developed for low adsorbate coverages which are not always representative of realistic heterogeneous catalytic environments. Herein, we present generalized linear scaling relations on transition metals that explicitly consider adsorbate-coadsorbate interactions at variable coverages. The slopes of these scaling relations do not follow the simple bond counting principles that govern scaling on transition metals at lower coverages. The deviations from bond counting are explained using a pairwise interaction model wherein the interaction parameter determines the slope of the scaling relationship on a given metal at variable coadsorbate coverages, and the slope across different metals at fixed coadsorbate coverage is approximated by adding a coverage-dependent correction to the standard bond counting contribution. The analysis provides a compact explanation for coverage-dependent deviations from bond counting in scaling relationships and suggests a useful strategy for incorporation of coverage effects into catalytic trends studies.

Continuous hemoadsorption with a cytokine adsorber during sepsis - a review of the literature.

PubMed

Houschyar, Khosrow S; Pyles, Malcolm N; Rein, Susanne; Nietzschmann, Ina; Duscher, Dominik; Maan, Zeshaan N; Weissenberg, Kristian; Philipps, Hubertus M; Strauss, Catharina; Reichelt, Beate; Siemers, Frank

2017-05-29

Sepsis is a well-recognized healthcare issue worldwide, ultimately resulting in significant mortality, morbidity and resource utilization during and after critical illness. In its most severe form, sepsis causes multi-organ dysfunction that produces a state of critical illness characterized by severe immune dysfunction and catabolism. Sepsis induces the activation of complement factor via 3 pathways and the release of inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin-1beta (IL-1β), resulting in a systemic inflammatory response. The inflammatory cytokines and nitric oxide release induced by sepsis decrease systemic vascular resistance, resulting in profound hypotension. The combination of hypotension and microvascular occlusion results in tissue ischemia and ultimately leads to multiple organ failure. Several clinical and experimental studies have reported that treatment using adsorption of cytokines is beneficial during endotoxemia and sepsis. This review article analyzes the efficacy of CytoSorb® adsorber in reducing the inflammatory response during sepsis. The CytoSorb® adsorber is known to have excellent adsorption rates for inflammatory cytokines such as IL-1β, IL-6, IL-8, IL-10, and TNF-α. Studies have demonstrated that treatment with cytokine adsorbing columns has beneficial effects on the survival rate and inflammatory responses in animal septic models. Additionally, several cases have been reported in which treatment with cytokine adsorbing columns is very effective in hemodynamic stabilization and in preventing organ failure in critically ill patients. Although further investigations and clinical trials are needed, treatment with cytokine adsorbing columns may play an important role in the treatment of sepsis in the near future.

The effect of sputter temperature on vacancy island behavior on Ni(111) measured by photoemission of adsorbed xenon

NASA Astrophysics Data System (ADS)

Malafsky, Geoffrey P.

1994-04-01

The temperature dependence of vacancy coalescence on an ion bombarded Ni(111) surface is measured by photoemission of adsorbed xenon (PAX). The Ni(111) crystal is sputtered by a low fluence (0.06 ML incident ions) Ar + ion beam with incident kinetic energies of 500-3000 eV. The Xe coverage decreases rapidly with increasing temperature between 88 and 375 K with little additional change from 375 to 775 K. The PAX spectra are acquired with a Xe chamber pressure of 8 × 10 -10 Torr and at a temperature of 88 K. Under these conditions, the Xe is selectively adsorbed at defect sites which would make the Xe coverage proportional to the surface defect density on simple defect structures but the large size of the Xe atom relative to the Ni atom prevents the direct relationship of Xe coverage to the defect density when complex and varying defect structures are present. The decrease in Xe coverage is not attributed to the loss of defect sites by adatom-vacancy recombination but the changing vacancy island shape and size with temperature which alters the ratio of adsorbed Xe atoms to surface vacancy sites. This ratio decreases with increasing temperature as the vacancy islands progress from small and irregularly shaped islands to larger and hexagonally shaped islands. This transition is seen in Monte Carlo simulations of the kinetically driven atomic diffusion on the sputtered surface.

Many-body dispersion effects in the binding of adsorbates on metal surfaces

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

Maurer, Reinhard J.; Ruiz, Victor G.; Tkatchenko, Alexandre

2015-09-14

A correct description of electronic exchange and correlation effects for molecules in contact with extended (metal) surfaces is a challenging task for first-principles modeling. In this work, we demonstrate the importance of collective van der Waals dispersion effects beyond the pairwise approximation for organic–inorganic systems on the example of atoms, molecules, and nanostructures adsorbed on metals. We use the recently developed many-body dispersion (MBD) approach in the context of density-functional theory [Tkatchenko et al., Phys. Rev. Lett. 108, 236402 (2012) and Ambrosetti et al., J. Chem. Phys. 140, 18A508 (2014)] and assess its ability to correctly describe the binding ofmore » adsorbates on metal surfaces. We briefly review the MBD method and highlight its similarities to quantum-chemical approaches to electron correlation in a quasiparticle picture. In particular, we study the binding properties of xenon, 3,4,9,10-perylene-tetracarboxylic acid, and a graphene sheet adsorbed on the Ag(111) surface. Accounting for MBD effects, we are able to describe changes in the anisotropic polarizability tensor, improve the description of adsorbate vibrations, and correctly capture the adsorbate–surface interaction screening. Comparison to other methods and experiment reveals that inclusion of MBD effects improves adsorption energies and geometries, by reducing the overbinding typically found in pairwise additive dispersion-correction approaches.« less

What Determines the Amount Students Borrow? Revisiting the Crisis-Convenience Debate

ERIC Educational Resources Information Center

Hart, Natala K.; Mustafa, Shoumi

2008-01-01

Recent studies have questioned the wisdom in blaming college costs for the escalation of student loans. It would appear that less affluent students borrow large amounts because inexpensive subsidized loans are available. This study attempted to verify the claim, estimating a model of the amount of loan received by students as a function of net…

Thermoelectric transport properties of Ti doped/adsorbed monolayer blue phosphorene.

PubMed

Zhu, Lin; Li, Bowen; Yao, Kailun

2018-08-10

Thermoelectric transport properties of Ti doped or adsorbed monolayer blue phosphorene are investigated by density functional theory combined with the nonequilibrium Green's function formalism. The thermal giant magnetoresistance and a nearly 100% spin polarization which solely relies on the temperature gradient of electrodes without bias or gate voltage are observed. Moreover, the spin Seebeck effect is also found. Furthermore, taking into account the electronic and phonon dispersion, the thermoelectric merit for Ti doping in the monolayer blue phosphorene at room temperature is also studied, the maximum value of thermoelectric merit can reach 1.01 near the Fermi level. The results indicate that Ti doped or adsorbed monolayer blue phosphorene has potential application in both spintronics and spin caloritronics.

Removal of Copper(II) Ions in Aqueous Solutions Using Tannin-Rich Plants as Natural Bio-Adsorbents

NASA Astrophysics Data System (ADS)

Paksamut, J.; Boonsong, P.

2018-03-01

In this study, the purpose of our interest is to investigatethe adsorption behavior of copper (II) ions in aqueous solution using some tannin-rich plants as natural bio-adsorbents such as mangosteen peels (Garciniamangostana L.), cassava leaves (Manihotesculenta Crantz) and Thai copper pod leaves (Sennasiamea (Lam.)) as powder form in different dosage of adsorbent plant materials.The adsorption capacities at different pH of solution and contact time were performed.All the experiments in this studywere chosen at room temperature by batch technique. From the experimental results showed that cassava leaves gave better adsorbent properties than mangosteen peels and Thai copper pod leaves. The increasing dosage of all adsorbents and contact time have been found to increase adsorption capacities. In this respect, the adsorption capacities depend crucially on the adsorbents and contact time. The optimum pH of copper (II) ions adsorption was pH4. According to this work, it was observed that bioadsorbent materials from tannin-rich plants could be used to remove copper (II) ions from aqueous solutions.

[Management of severe sepsis using a Cytokin-adsorber].

PubMed

Houschyar, Khosrow Siamak; Rein, Susanne; Weissenberg, Kristian; Duscher, Dominik; Philipps, Hubertus Maria; Nietzschmann, Ina; Schulz, Torsten; Siemers, Frank

2018-02-01

Based on a representative case, which was treated in our center for severe burn injuries, the severity of the Waterhouse-Friderichsen syndrome and the complexity of the prolonged course of treatment are illustrated. Special attention is focused on the new treatment paradigm using the CytoSorb® adsorber.

UiO-66-Type Metal-Organic Framework with Free Carboxylic Acid: Versatile Adsorbents via H-bond for Both Aqueous and Nonaqueous Phases.

PubMed

Song, Ji Yoon; Ahmed, Imteaz; Seo, Pill Won; Jhung, Sung Hwa

2016-10-03

The metal-organic framework (MOF) UiO-66 was synthesized in one step from zirconium chloride and isophthalic acid (IPA), together with the usual link material, terephthalic acid (TPA). UiO-66 with free -COOH can be obtained in a facile way by replacing up to 30% of the TPA with IPA. However, the chemical and thermal stability of the synthesized MOFs decreased with increasing IPA content used in the syntheses, suggesting an increase in the population of imperfect bonds in the MOFs because of the asymmetrical structure of IPA. The obtained MOFs with free -COOH were applied in liquid-phase adsorptions from both water and model fuel to not only estimate the potential applications but also confirm the presence of -COOH in the MOFs. The adsorbed amounts of several organics (triclosan and oxybenzone from water and indole and pyrrole from fuel) increased monotonously with increasing IPA content applied in MOF synthesis (or -COOH in the MOFs). The favorable contribution of free -COOH to adsorption can be explained by H-bonding, and the direction of H-bonds (adsorbates: H donor; MOFs: H acceptor) was confirmed by the adsorption of oxybenzone in a wide pH range. The versatile applications of the MOFs with -COOH in adsorptions from both polar and nonpolar phases are remarkable considering that hydrophobic and hydrophilic adsorbents are generally required for water and fuel purification, respectively. Finally, the presence of free -COOH in the MOFs was confirmed by liquid-phase adsorptions together with general Fourier transform infrared analyses and decreased chemical and thermal stability.

Decontamination of adsorbed chemical warfare agents on activated carbon using hydrogen peroxide solutions.

PubMed

Osovsky, Ruth; Kaplan, Doron; Nir, Ido; Rotter, Hadar; Elisha, Shmuel; Columbus, Ishay

2014-09-16

Mild treatment with hydrogen peroxide solutions (3-30%) efficiently decomposes adsorbed chemical warfare agents (CWAs) on microporous activated carbons used in protective garments and air filters. Better than 95% decomposition of adsorbed sulfur mustard (HD), sarin, and VX was achieved at ambient temperatures within 1-24 h, depending on the H2O2 concentration. HD was oxidized to the nontoxic HD-sulfoxide. The nerve agents were perhydrolyzed to the respective nontoxic methylphosphonic acids. The relative rapidity of the oxidation and perhydrolysis under these conditions is attributed to the microenvironment of the micropores. Apparently, the reactions are favored due to basic sites on the carbon surface. Our findings suggest a potential environmentally friendly route for decontamination of adsorbed CWAs, using H2O2 without the need of cosolvents or activators.

Miscibility and interaction between 1-alkanol and short-chain phosphocholine in the adsorbed film and micelles.

PubMed

Takajo, Yuichi; Matsuki, Hitoshi; Kaneshina, Shoji; Aratono, Makoto; Yamanaka, Michio

2007-09-01

The miscibility and interaction of 1-hexanol (C6OH) and 1-heptanol (C7OH) with 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) in the adsorbed films and micelles were investigated by measuring the surface tension of aqueous C6OH-DHPC and aqueous C7OH-DHPC solutions. The surface density, the mean molecular area, the composition of the adsorbed film, and the excess Gibbs energy of adsorption g(H,E), were estimated. Further, the critical micelle concentration of the mixtures was determined from the surface tension versus molality curves; the micellar composition was calculated. The miscibility of the 1-alkanols and DHPC molecules in the adsorbed film and micelles was examined using the phase diagram of adsorption (PDA) and that of micellization (PDM). The PDA and the composition dependence of g(H,E) indicated the non-ideal mixing of the 1-alkanols and DHPC molecules due to the attractive interaction between the molecules in the adsorbed film, while the PDM indicated that the 1-alkanol molecules were not incorporated in the micelles within DHPC rich region. The dependence of the mean molecular area of the mixtures on the surface composition suggested that the packing property of the adsorbed film depends on the chain length of 1-alkanol: C6OH expands the DHPC adsorbed film more than C7OH.

Large Amounts of Reactivated Virus in Tears Precedes Recurrent Herpes Stromal Keratitis in Stressed Rabbits Latently Infected with Herpes Simplex Virus

PubMed Central

Perng, Guey-Chuen; Osorio, Nelson; Jiang, Xianzhi; Geertsema, Roger; Hsiang, Chinhui; Brown, Don; BenMohamed, Lbachir; Wechsler, Steven L.

2017-01-01

Aim Recurrent herpetic stromal keratitis (rHSK), due to an immune response to reactivation of herpes simplex virus (HSV-1), can cause corneal blindness. The development of therapeutic interventions such as drugs and vaccines to decrease rHSK have been hampered by the lack of a small and reliable animal model in which rHSK occurs at a high frequency during HSV-1 latency. The aim of this study is to develop a rabbit model of rHSK in which stress from elevated temperatures increases the frequency of HSV-1 reactivations and rHSK. Materials and methods Rabbits latently infected with HSV-1 were subjected to elevated temperatures and the frequency of viral reactivations and rHSK were determined. Results In an experiment in which rabbits latently infected with HSV-1 were subjected to ill-defined stress as a result of failure of the vivarium air conditioning system, reactivation of HSV-1 occurred at over twice the normal frequency. In addition, 60% of eyes developed severe rHSK compared to <1% of eyes normally. All episodes of rHSK were preceded four to five days prior by an unusually large amount of reactivated virus in the tears of that eye and whenever this unusually large amount of reactivated virus was detected in tears, rHSK always appeared 4–5 days later. In subsequent experiments using well defined heat stress the reactivation frequency was similarly increased, but no eyes developed rHSK. Conclusions The results reported here support the hypothesis that rHSK is associated not simply with elevated reactivation frequency, but rather with rare episodes of very high levels of reactivated virus in tears 4–5 days earlier. PMID:25859798

Theory of raman scattering from molecules adsorbed at semiconductor surfaces

NASA Astrophysics Data System (ADS)

Ueba, H.

1983-09-01

A theory is presented to calculate the Raman polarizability of an adsorbed molecule at a semiconductor surface, where the electronic excitation in the molecular site interacts with excitons (elementary excitations in the semiconductor) through non-radiative energy transfer between them, in an intermediate state in the Raman scattering process. The Raman polarizability thus calculated is found to exhibit a peak at the energy corresponding to a resonant excitation of excitons, thereby suggesting the possibility of surface enhanced Raman scattering on semiconductor surfaces. The mechanism studied here can also give an explanation of a recent observation of the Raman excitation profiles of p-NDMA and p-DMAAB adsorbed on ZnO or TiO 2, where those profiles were best described by assuming a resonant intermediate state of the exciton transition in the semiconductors. It is also demonstrated that in addition to vibrational Raman scattering, excitonic Raman scattering of adsorbed molecules will occur in the coupled molecule-semiconductor system, where the molecular returns to its ground electronic state by leaving an exciton in the semiconductor. A spectrum of the excitonic Raman scattering is expected to appear in the background of the vibrational Raman band and to be characterized by the electronic structure of excitons. A desirable experiment is suggested for an examination of the theory.

Hexadimethrine-montmorillonite nanocomposite: Characterization and application as a pesticide adsorbent

NASA Astrophysics Data System (ADS)

Gámiz, B.; Hermosín, M. C.; Cornejo, J.; Celis, R.

2015-03-01

The goal of this work was to prepare and characterize a novel functional material by the modification of SAz-1 montmorillonite with the cationic polymer hexadimethrine (SA-HEXAD), and to explore the potential use of this nanocomposite as a pesticide adsorbent. Comparative preparation and characterization with the well-known hexadecyltrimethylammonium-modified SAz-1 montmorillonite (SA-HDTMA) was also assessed. The characterization was performed by elemental analysis, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), physisorption of N2, scanning electron microscopy (SEM) and Z potential measurements. The characterization and adsorption experiments showed that the extent of pesticide adsorption was markedly subjected to the structure and features of the surface of each organo-clay and also to the nature of the considered pesticide. SA-HEXAD displayed a high affinity for anionic pesticides which, presumably, were adsorbed by electrostatic attraction on positively-charged ammonium groups of the polymer not directly interacting with the clay. In contrast, SA-HDTMA displayed great adsorption of both uncharged and anionic pesticides with predominance of hydrophobic interactions. This work provided information about the surface properties of a new organic-inorganic nanohybrid material, SA-HEXAD, and its potential as an adsorbent for the removal of anionic organic pollutants from aqueous solutions.

In situ modification of chromatography adsorbents using cold atmospheric pressure plasmas

NASA Astrophysics Data System (ADS)

Olszewski, P.; Willett, T. C.; Theodosiou, E.; Thomas, O. R. T.; Walsh, J. L.

2013-05-01

Efficient manufacturing of increasingly sophisticated biopharmaceuticals requires the development of new breeds of chromatographic materials featuring two or more layers, with each layer affording different functions. This letter reports the in situ modification of a commercial beaded anion exchange adsorbent using atmospheric pressure plasma generated within gas bubbles. The results show that exposure to He-O2 plasma in this way yields significant reductions in the surface binding of plasmid DNA to the adsorbent exterior, with minimal loss of core protein binding capacity; thus, a bi-layered chromatography material exhibiting both size excluding and anion exchange functionalities within the same bead is produced.

Natural adsorbents of dyes from aqueous solution

NASA Astrophysics Data System (ADS)

Rahmani, Meryem; El Hajjaji, souad; Dahchour, Abdelmalek; El M'Rabet, Mohammadine

2017-04-01

Contamination of natural waters is a current environmental problem and lot of work has been done to find methods for its, prevention and remediation such as ionic exchange, adsorption on active carbon, filtration, electrolysis, biodegradation …etc. Adsorption is one of the most applied methods according to its effectiveness and easy management. Some adsorbents with good properties such as active alumina, zeolites, crop residues … etc, are suitable to substitute usual active carbon. This study aimed at the removal of dyes using oil shale as natural support, and its optimization by factorial experiment. Three factors were considered namly:pollutant concentration, pH and weight of the adsorbent. Tests have been performed with cationic and anionic dyes. Experimental results show that pseudo-first-order kinetic model provided the best fit to the experimental data for the adsorption by the oil shale. Langmuir, Freundlich and Temkin isotherm models were tested to fit experimental data, the adsorption equilibrium was well described by Freundlich isotherm for methylorange and Temkin for methyl blue. Analysis were completed by oil shale characterization educing XRD, IR, XRF techniques, and cationic exchange capacity.

Effects of pyrolysis temperature, time and leaf litter and powder coal ash addition on sludge-derived adsorbents for nitrogen oxide.

PubMed

Ren, Xiaoli; Liang, Baohong; Liu, Min; Xu, Xiaoyuan; Cui, Meihua

2012-12-01

The objective of this research was to seek a cost effective solution to prepare adsorbents for nitrogen oxide from surplus sludge. Leaf litter and powder coal ash were used as cheap and easily available additives. An adsorbent for nitrogen oxide was prepared by pyrolysis of dried sludge mixed with zinc chloride. Under optimum pyrolysis conditions of 375°C for 90 min and a zinc chloride content of 30%, the surface area of the adsorbent with leaf litter was 514.41 m(2)/g, the surface area of the adsorbent with powder coal ash was 432.34 m(2)/g, respectively, corresponding to an increase of 90.70% and 60.27% when compared to the adsorbent without the additives. The saturated adsorption quantity of the adsorbent with leaf litter reached 271 mg/g at 20°C. The results indicated that the sludge-derived adsorbent was quite promising for nitrogen oxide removal. Copyright © 2012 Elsevier Ltd. All rights reserved.

Feasibility of using drinking water treatment residuals as a novel chlorpyrifos adsorbent.

PubMed

Zhao, Yuanyuan; Wang, Changhui; Wendling, Laura A; Pei, Yuansheng

2013-08-07

Recent efforts have increasingly focused on the development of low-cost adsorbents for pesticide retention. In this work, the novel reuse of drinking water treatment residuals (WTRs), a nonhazardous ubiquitous byproduct, as an adsorbent for chlorpyrifos was investigated. Results showed that the kinetics and isothermal processes of chlorpyrifos sorption to WTRs were better described by a pseudo-second-order model and by the Freundlich equation, respectively. Moreover, compared with paddy soil and other documented absorbents, the WTRs exhibited a greater affinity for chlorpyrifos (log Koc = 4.76-4.90) and a higher chlorpyrifos sorption capacity (KF = 5967 mg(1-n)·L·kg(-1)) owing to the character and high content of organic matter. Further investigation demonstrated that the pH had a slight but statistically insignificant effect on chlorpyrifos sorption to WTRs; solution ionic strength and the presence of low molecular weight organic acids both resulted in concentration-dependent inhibition effects. Overall, these results confirmed the feasibility of using WTRs as a novel chlorpyrifos adsorbent.

Properties and potential environmental applications of carbon adsorbents from waste tire rubber

USGS Publications Warehouse

Lehmann, C.M.B.; Rameriz, D.; Rood, M.J.; Rostam-Abadi, M.

2000-01-01

The properties of tire-derived carbon adsorbents (TDCA) produced from select tire chars were compared with those derived from an Illinois coal and pistachio nut shells. Chemical analyses of the TDCA indicated that these materials contain metallic elements not present in coal-and nut shell-derived carbons. These metals, introduced during the production of tire rubber, potentially catalyze steam gasification reactions of tire char. TDCA carbons contained larger meso-and macopore volumes than their counterparts derived from coal and nut shell (on the moisture-and ash-free-basis). Adsorptive properties of the tire-derived adsorbent carbons for air separation, gas storage, and gas clean up were also evaluated and compared with those of the coal-and nut shell derived carbons as well as a commercial activated carbon. The results revealed that TDCA carbons are suitable adsorbents for removing vapor-phase mercury from combustion flue gases and hazardous organic compounds from industrial gas streams.

Insight into Multifunctional Reactive Adsorbents: Engaging Chemistry, Porosity, Photoactivity and Conductivity into Decontamination Process

DTIC Science & Technology

2017-06-07

AUTHORS 7. PERFORMING ORGANIZATION NAMES AND ADDRESSES 15. SUBJECT TERMS b. ABSTRACT 2. REPORT TYPE 17. LIMITATION OF ABSTRACT 15. NUMBER OF PAGES 5d...Insight Into Multifunctional Reactive Adsorbents: Engaging Chemistry , Porosity, Photoactivity and Conductivity into Decontamination Process The...Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 CWA decontamination, multifunctional adsorbents, porosity, surface chemistry

Gd uptake experiments for preliminary set of functionalized adsorbents

DOE Data Explorer

Clinton Noack

2015-03-16

These data summarize adsorption experiments conducted with Gd in 0.5 M NaCl. Results represent preliminary, proof-of-concept data utilizing fine-powder silica gel as the adsorbent support. Future testing will focus on larger, application-appropriate beads.

[Ability of typical greenery shrubs of Beijing to adsorb and arrest PM2.5 ].

PubMed

Liang, Dan; Wang, Bin; Wang, Yun-qi; Zhang, Hui-lan; Yang, Song-nan; Li, Ang

2014-09-01

Four typical types of green shrubs of Beijing (Euonymus japonicus, Buxus microphylla, Berberis thunbergii cv. atropurpurea, Taxus cuspidate cv. nana) were selected to study their capacities in adsorbing and arresting PM2.5 using both field observations and air chamber simulations. Concurrently, in order to analyze the pollution characteristics of Beijing in winter and spring, the PM2.5 concentrations of December 2012 to May 2013 were collected. Experimental results showed that: From the gas chamber experiments, the ability to adsorb and arrest PM2.5 was in the order of Berberis thunbergii cv. atropurpurea > Buxus microphylla > Taxus cuspidate cv. nana > Euonymus japonicus, mainly due to the differences in leaf characteristics; Outside measurement results showed that the ability to adsorb and arrest PM2.5 was ranked as Buxus microphylla > Berberis thunbergii cv. atropurpurea > Taxus cuspidate cv. nana > Euonymus japonicus. Chamber simulation and outdoor observation showed that Buxus microphylla and Berberis thunbergii cv. atropurpurea had strong ability to adsorb and arrest PM2.5; Meanwhile, the slight differences between the chamber simulation and outdoor observation results might be related to plant structure. Compared to tree species, the planting condition of shrub species was loose, and it greened quickly; By analyzing the Beijing PM2.5 concentration values in winter and spring, it was found that the PM2.5 concentration was particularly high in the winter of Beijing, and evergreen shrubs maintained the ability to adsorb and arrest PM2.5.

Removal of uranium from aqueous solution by a low cost and high-efficient adsorbent

NASA Astrophysics Data System (ADS)

Liu, Yun-Hai; Wang, You-Qun; Zhang, Zhi-Bin; Cao, Xiao-Hong; Nie, Wen-Bin; Li, Qin; Hua, Rong

2013-05-01

In this study, a low-cost and high-efficient carbonaceous adsorbent (HTC-COOH) with carboxylic groups was developed for U(VI) removal from aqueous solution compared with the pristine hydrothermal carbon (HTC). The structure and chemical properties of resultant adsorbents were characterized by Scanning electron microscope (SEM), N2 adsorption-desorption, Fourier transform-infrared spectra (FT-IR) and acid-base titration. The key factors (solution pH, contact time, initial U(VI) concentrations and temperature) affected the adsorption of U(VI) on adsorbents were investigated using batch experiments. The adsorption of U(VI) on HTC and HTC-COOH was pH-dependent, and increased with temperature and initial ion concentration. The adsorption equilibrium of U(VI) on adsorbents was well defined by the Langmuir isothermal equation, and the monolayer adsorption capacity of HTC-COOH was found to be 205.8 mg/g. The kinetics of adsorption was very in accordance with the pseudo-second-order rate model. The adsorption processes of U(VI) on HTC and HTC-COOH were endothermic and spontaneous in nature according to the thermodynamics of adsorption. Furthermore, HTC-COOH could selectively adsorption of U(VI) in aqueous solution containing co-existing ions (Mg2+, Co2+, Ni2+, Zn2+ and Mn2+). From the results of the experiments, it is found that the HTC-COOH is a potential adsorbent for effective removal of U(VI) from polluted water.

Enhancement of mass transfer by ultrasound: Application to adsorbent regeneration and food drying/dehydration.

PubMed

Yao, Ye

2016-07-01

The physical mechanisms of heat and mass transfer enhancement by ultrasound have been identified by people. Basically, the effect of 'cavitation' induced by ultrasound is the main reason for the enhancement of heat and mass transfer in a liquid environment, and the acoustic streaming and vibration are the main reasons for that in a gaseous environment. The adsorbent regeneration and food drying/dehydration are typical heat and mass transfer process, and the intensification of the two processes by ultrasound is of complete feasibility. This paper makes an overview on recent studies regarding applications of power ultrasound to adsorbent regeneration and food drying/dehydration. The concerned adsorbents include desiccant materials (typically like silica gel) for air dehumidification and other ones (typically active carbon and polymeric resin) for water treatment. The applications of ultrasound in the regeneration of these adsorbents have been proved to be energy saving. The concerned foods are mostly fruits and vegetables. Although the ultrasonic treatment may cause food degradation or nutrient loss, it can greatly reduce the food processing time and decrease drying temperature. From the literature, it can be seen that the ultrasonic conditions (i.e., acoustic frequency and power levels) are always focused on during the study of ultrasonic applications. The increasing number of relevant studies argues that ultrasound is a very promising technology applied to the adsorbent regeneration and food drying/dehydration. Copyright © 2016 Elsevier B.V. All rights reserved.

Competitive Adsorption of Metals onto Magnetic Graphene Oxide: Comparison with Other Carbonaceous Adsorbents

PubMed Central

Hur, Jin; Shin, Jaewon; Yoo, Jeseung; Seo, Young-Soo

2015-01-01

Competitive adsorption isotherms of Cu(II), Pb(II), and Cd(II) were examined on a magnetic graphene oxide (GO), multiwalled carbon nanotubes (MWCNTs), and powered activated carbon (PAC). A series of analyses confirmed the successful synthesis of the magnetic GO based on a simple ultrasonification method. Irrespective of the adsorbents, the adsorption was highly dependent on pH, and the adsorption was well described by the Langmuir isotherm model. The maximum adsorption capacities of the adsorbents were generally higher in the order of Pb(II) > Cu(II) > Cd(II), which is the same as the degree of the electronegativity and the hydrated radius of the metals, suggesting that the metal adsorption may be governed by an ion exchange between positively charged metals and negatively charged surfaces, as well as diffusion of metals into the surface layer. The adsorption of each metal was mostly lower for multi- versus single-metal systems. The antagonistic effects were influenced by solution pH as well as the type of metals, and they were higher in the order of the magnetic GO > MWCNT > PAC. Dissolved HS played a greater role than HS adsorbed onto the adsorbents, competing with the adsorption sites for metal complexation. PMID:25861683

Innovative Elution Processes for Recovering Uranium and Transition Metals from Amidoxime-based Adsorbents

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

Wai, Chien M.

Amidoxime-based polymer fibers are considered one of the most promising materials for sequestering uranium from seawater. The high-surface-area polymer fibers containing amidoxime and carboxylate groups synthesized by Oak Ridge National Lab (ORNL-AF1) show very high uranium adsorption capacities known in the literature. Effective elution of uranium and repeated use of the adsorbent are important factors affecting the cost of producing uranium from seawater using this material. Traditional acid leaching of uranium followed by KOH conditioning of the fiber causes chemical changes and physical damage to the ORNL-AF1 adsorbent. Two alkaline solution leaching methods were developed by this project, one usesmore » a highly concentrated (3 M) potassium bicarbonate solution at pH 8.3 and 40 °C; the other uses a mixture of sodium carbonate and hydrogen peroxide at pH 10.4. Both elution methods do not require KOH conditioning prior to reusing the fiber adsorbent. The conditions of eluting uranium from the amidoxime-based adsorbent using these alkaline solutions are confirmed by thermodynamic calculations. The bicarbonate elution method is selective for uranium recovery compared to other elution methods and causes no chemical change to the fiber material based on FTIR spectroscopy« less

Sacrificial adsorbate for surfactants utilized in chemical floods of enhanced oil recovery operations

DOEpatents