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Sample records for capacity mercury adsorption

  1. The adsorptive capacity of vapor-phase mercury chloride onto powdered activated carbon derived from waste tires

    SciTech Connect

    Hsun-Yu Lin; Chung-Shin Yuan; Chun-Hsin Wu; Chung-Hsuang Hung

    2006-11-15

    Injection of powdered activated carbon (PAC) upstream of particulate removal devices (such as electrostatic precipitator and baghouses) has been used effectively to remove hazardous air pollutants, particularly mercury containing pollutants, emitted from combustors and incinerators. Compared with commercial PACs (CPACs), an alternative PAC derived from waste tires (WPAC) was prepared for this study. The equilibrium adsorptive capacity of mercury chloride (HgCl{sub 2}) vapor onto the WPAC was further evaluated with a self-designed bench-scale adsorption column system. The adsorption temperatures investigated in the adsorption column were controlled at 25 and 150{sup o}C. The superficial velocity and residence time of the flow were 0.01 m/sec and 4 sec, respectively. The adsorption column tests were run under nitrogen gas flow. Experimental results showed that WPAC with higher Brunauer Emmett Teller (BET) surface area could adsorb more HgCl{sub 2} at room temperature. The equilibrium adsorptive capacity of HgCl{sub 2} for WPAC measured in this study was 1.49 x 10{sup -1} mg HgCl{sub 2}/g PAC at 25{sup o}C with an initial HgCl{sub 2} concentration of 25 {mu}g/m{sup 3}. With the increase of adsorption temperature {le} 150{sup o}C, the equilibrium adsorptive capacity of HgCl{sub 2} for WPAC was decreased to 1.34 x 10{sup -1} mg HgCl{sub 2}/g PAC. Furthermore, WPAC with higher sulfur contents could adsorb even more HgCl{sub 2}. It was demonstrated that the mechanisms for adsorbing HgCl{sub 2} onto WPAC were physical adsorption and chemisorption at 25 and 150{sup o}C, respectively. 35 refs., 4 figs., 4 tabs.

  2. The adsorptive capacity of vapor-phase mercury chloride onto powdered activated carbon derived from waste tires.

    PubMed

    Lin, Hsun-Yu; Yuan, Chung-Shin; Wu, Chun-Hsin; Hung, Chung-Hsuang

    2006-11-01

    Injection of powdered activated carbon (PAC) upstream of particulate removal devices (such as electrostatic precipitator and baghouses) has been used effectively to remove hazardous air pollutants, particularly mercury-containing pollutants, emitted from combustors and incinerators. Compared with commercial PACs (CPACs), an alternative PAC derived from waste tires (WPAC) was prepared for this study. The equilibrium adsorptive capacity of mercury chloride (HgCl2) vapor onto the WPAC was further evaluated with a self-designed bench-scale adsorption column system. The adsorption temperatures investigated in the adsorption column were controlled at 25 and 150 degrees C. The superficial velocity and residence time of the flow were 0.01 m/sec and 4 sec, respectively. The adsorption column tests were run under nitrogen gas flow. Experimental results showed that WPAC with higher Brunauer-Emmett-Teller (BET) surface area could adsorb more HgCl2 at room temperature. The equilibrium adsorptive capacity of HgCl2 for WPAC measured in this study was 1.49 x 10(-1) mg HgCl2/g PAC at 25 degrees C with an initial HgCI2 concentration of 25 microg/m3. With the increase of adsorption temperature < or = 150 degrees C, the equilibrium adsorptive capacity of HgCl2 for WPAC was decreased to 1.34 x 10(-1) mg HgCl2/g PAC. Furthermore, WPAC with higher sulfur contents could adsorb even more HgCl2 because of the reactions between sulfur and Hg2+ at 150 degrees C. It was demonstrated that the mechanisms for adsorbing HgCl2 onto WPAC were physical adsorption and chemisorption at 25 and 150 degrees C, respectively. Experimental results also indicated that the apparent overall driving force model appeared to have the good correlation with correlation coefficients (r) > 0.998 for HgCl2 adsorption at 25 and 150 degrees C. Moreover, the equilibrium adsorptive capacity of HgCl2 for virgin WPAC was similar to that for CPAC at 25 degrees C, whereas it was slightly higher for sulfurized WPAC than for

  3. Removal of mercury by adsorption: a review.

    PubMed

    Yu, Jin-Gang; Yue, Bao-Yu; Wu, Xiong-Wei; Liu, Qi; Jiao, Fei-Peng; Jiang, Xin-Yu; Chen, Xiao-Qing

    2016-03-01

    Due to natural and production activities, mercury contamination has become one of the major environmental problems over the world. Mercury contamination is a serious threat to human health. Among the existing technologies available for mercury pollution control, the adsorption process can get excellent separation effects and has been further studied. This review is attempted to cover a wide range of adsorbents that were developed for the removal of mercury from the year 2011. Various adsorbents, including the latest adsorbents, are presented along with highlighting and discussing the key advancements on their preparation, modification technologies, and strategies. By comparing their adsorption capacities, it is evident from the literature survey that some adsorbents have shown excellent potential for the removal of mercury. However, there is still a need to develop novel, efficient adsorbents with low cost, high stability, and easy production and manufacture for practical utility.

  4. Mercury adsorption-desorption and transport in soils.

    PubMed

    Liao, Lixia; Selim, H M; Delaune, R D

    2009-01-01

    Kinetic sorption and column miscible displacement transport experiments were performed to quantify the extent of retention/release and the mobility of mercury in different soils. Results indicated that adsorption of mercury was rapid and highly nonlinear with sorption capacities having the following sequence: Sharkey clay > Olivier loam > Windsor sand. Mercury adsorption by all soils was strongly irreversible where the amounts released or desorbed were often less than 1% of that applied. Moreover, the removal of soil organic matter resulted in a decrease of mercury adsorption in all soils. Adsorption was described with limited success using a nonlinear (Freundlich) model. Results from the transport experiments indicated that the mobility of mercury was highly retarded, with extremely low concentrations of mercury in column effluents. Furthermore, mercury breakthrough curves exhibited erratic patterns with ill-distinguished peaks. Therefore, mercury is best regarded as strongly retained and highly "immobile" in the soils investigated. This is most likely due to highly stable complex formation (irreversible forms) and strong binding to high-affinity sites. In a column packed with reference sand material, a symmetric breakthrough curve was obtained where the recovery of mercury in the leachate was only 17.3% of that applied. Mercury retention by the reference sand was likely due to adsorption by quartz and metal-oxides.

  5. Effects of sulfur impregnation temperature on the properties and mercury adsorption capacities of activated carbon fibers (ACFs).

    PubMed

    Hsi, H C; Rood, M J; Rostam-Abadi, M; Chen, S; Chang, R

    2001-07-01

    Laboratory studies were conducted to determine the role of sulfur functional groups and micropore surface area of carbon-based adsorbents on the adsorption of Hg0 from simulated coal combustion flue gases. In this study, raw activated carbon fibers that are microporous (ACF-20) were impregnated with elemental sulfur between 250 and 650 degrees C. The resulting samples were saturated with respect to sulfur content. Total sulfur content of the sulfur impregnated ACF samples decreased with increasing impregnation temperatures from 250 and 500 degrees C and then remained constant to 650 degrees C. Results from sulfur K-edge X-ray absorption near-edge structure (S-XANES) spectroscopy showed that sulfur impregnated on the ACF samples was in both elemental and organic forms. As sulfur impregnation temperature increased, however, the relative amounts of elemental sulfur decreased with a concomitant increase in the amount of organic sulfur. Thermal analyses and mass spectrometry revealed that sulfur functional groups formed at higher impregnation temperatures were more thermally stable. In general, sulfur impregnation decreased surface area and increased equilibrium Hg0 adsorption capacity when compared to the raw ACF sample. The ACF sample treated with sulfur at 400 degrees C had a surface area of only 94 m2/g compared to the raw ACF sample's surface area of 1971 m2/g, but at least 86% of this sample's surface area existed as micropores and it had the largest equilibrium Hg0 adsorption capacities (2211-11,343 micrograms/g). Such a result indicates that 400 degrees C is potentially an optimal sulfur impregnation temperature for this ACF. Sulfur impregnated on the ACF that was treated at 400 degrees C was in both elemental and organic forms. Thermal analyses and CS2 extraction tests suggested that elemental sulfur was the main form of sulfur affecting the Hg0 adsorption capacity. These findings indicate that both the presence of elemental sulfur on the adsorbent and a

  6. Effects of sulfur impregnation temperature on the properties and mercury adsorption capacities of activated carbon fibers (ACFs)

    USGS Publications Warehouse

    Hsi, H.-C.; Rood, M.J.; Rostam-Abadi, M.; Chen, S.; Chang, R.

    2001-01-01

    Laboratory studies were conducted to determine the role of sulfur functional groups and micropore surface area of carbon-based adsorbents on the adsorption of Hg0 from simulated coal combustion flue gases. In this study, raw activated carbon fibers that are microporous (ACF-20) were impregnated with elemental sulfur between 250 and 650 ??C. The resulting samples were saturated with respect to sulfur content. Total sulfur content of the sulfur impregnated ACF samples decreased with increasing impregnation temperatures from 250 and 500 ??C and then remained constant to 650 ??C. Results from sulfur K-edge X-ray absorption near-edge structure (S-XANES) spectroscopy showed that sulfur impregnated on the ACF samples was in both elemental and organic forms. As sulfur impregnation temperature increased, however, the relative amounts of elemental sulfur decreased with a concomitant increase in the amount of organic sulfur. Thermal analyses and mass spectrometry revealed that sulfur functional groups formed at higher impregnation temperatures were more thermally stable. In general, sulfur impregnation decreased surface area and increased equilibrium Hg0 adsorption capacity when compared to the raw ACF sample. The ACF sample treated with sulfur at 400 ??C had a surface area of only 94 m2/g compared to the raw ACF sample's surface area of 1971 m2/g, but at least 86% of this sample's surface area existed as micropores and it had the largest equilibrium Hg0adsorption capacities (2211-11343 ??g/g). Such a result indicates that 400 ??C is potentially an optimal sulfur impregnation temperature for this ACF. Sulfur impregnated on the ACF that was treated at 400 ??C was in both elemental and organic forms. Thermal analyses and CS2extraction tests suggested that elemental sulfur was the main form of sulfur affecting the Hg0 adsorption capacity. These findings indicate that both the presence of elemental sulfur on the adsorbent and a microporous structure are important properties for

  7. Preparation of hybrid organic-inorganic mesoporous silicas applied to mercury removal from aqueous media: Influence of the synthesis route on adsorption capacity and efficiency.

    PubMed

    Pérez-Quintanilla, Damián; Sánchez, Alfredo; Sierra, Isabel

    2016-06-15

    New hybrid organic-inorganic mesoporous silicas were prepared by employing three different synthesis routes and mercury adsorption studies were done in aqueous media using the batch technique. The organic ligands employed for the functionalization were derivatives of 2-mercaptopyrimidine or 2-mercaptothiazoline, and the synthesis pathways used were post-synthesis, post-synthesis with surface ion-imprinting and co-condensation with ion-imprinting. The incorporation of functional groups and the presence of ordered mesopores in the organosilicas was confirmed by XRD, TEM and SEM, nitrogen adsorption-desorption isotherms, (13)C MAS-NMR, (29)Si MAS-NMR, elemental and thermogravimetric analysis. The highest adsorption capacity and selectivity observed was for the material functionalized with 2-mercaptothiazoline ligand by means the co-condensation with ion-imprinting route (1.03 mmol g(-1) at pH 6). The prepared material could be potential sorbent for the extraction of this heavy metal from environmental and drinking waters.

  8. Mercury adsorption properties of sulfur-impregnated adsorbents

    USGS Publications Warehouse

    Hsi, N.-C.; Rood, M.J.; Rostam-Abadi, M.; Chen, S.; Chang, R.

    2002-01-01

    Carbonaceous and noncarbonaceous adsorbents were impregnated with elemental sulfur to evaluate the chemical and physical properties of the adsorbents and their equilibrium mercury adsorption capacities. Simulated coal combustion flue gas conditions were used to determine the equilibrium adsorption capacities for Hg0 and HgCl2 gases to better understand how to remove mercury from gas streams generated by coal-fired utility power plants. Sulfur was deposited onto the adsorbents by monolayer surface deposition or volume pore filling. Sulfur impregnation increased the total sulfur content and decreased the total and micropore surface areas and pore volumes for all of the adsorbents tested. Adsorbents with sufficient amounts of active adsorption sites and sufficient microporous structure had mercury adsorption capacities up to 4,509 ??g Hg/g adsorbent. Elemental sulfur, organic sulfur, and sulfate were formed on the adsorbents during sulfur impregnation. Correlations were established with R2>0.92 between the equilibrium Hg0/HgCl2 adsorption capacities and the mass concentrations of elemental and organic sulfur. This result indicates that elemental and organic sulfur are important active adsorption sites for Hg0 and HgCl2.

  9. Aqueous mercury adsorption by activated carbons.

    PubMed

    Hadi, Pejman; To, Ming-Ho; Hui, Chi-Wai; Lin, Carol Sze Ki; McKay, Gordon

    2015-04-15

    Due to serious public health threats resulting from mercury pollution and its rapid distribution in our food chain through the contamination of water bodies, stringent regulations have been enacted on mercury-laden wastewater discharge. Activated carbons have been widely used in the removal of mercuric ions from aqueous effluents. The surface and textural characteristics of activated carbons are the two decisive factors in their efficiency in mercury removal from wastewater. Herein, the structural properties and binding affinity of mercuric ions from effluents have been presented. Also, specific attention has been directed to the effect of sulfur-containing functional moieties on enhancing the mercury adsorption. It has been demonstrated that surface area, pore size, pore size distribution and surface functional groups should collectively be taken into consideration in designing the optimal mercury removal process. Moreover, the mercury adsorption mechanism has been addressed using equilibrium adsorption isotherm, thermodynamic and kinetic studies. Further recommendations have been proposed with the aim of increasing the mercury removal efficiency using carbon activation processes with lower energy input, while achieving similar or even higher efficiencies.

  10. Roles of metal/activated carbon hybridization on elemental mercury adsorption.

    PubMed

    Bae, Kyong-Min; Kim, Byung-Joo; Rhee, Kyong Yop; Park, Soo-Jin

    2014-08-01

    In this study, the elemental mercury removal behavior of metal (copper or nickel)/activated carbon hybrid materials were investigated. The pore structures and total pore volumes of the hybrid materials were analyzed using the N2/77 K adsorption isotherms. The microstructure and surface morphologies of the hybrid materials were characterized by X-ray diffraction and scanning electron microscopy, respectively. In the experimental results, the elemental mercury adsorption capacities of all copper/activated carbon hybrid materials were higher than that of the as-received material despite the decrease in specific surface areas and total pore volumes after the metal loading. All the samples containing the metal particles showed excellent elemental mercury adsorption. The Ni/ACs exhibited superior elemental mercury adsorption to those of Cu/ACs. This suggests that Ni/ACs have better elemental mercury adsorption due to the higher activity of nickel.

  11. Adsorption potential of mercury(II) from aqueous solutions onto Romanian peat moss.

    PubMed

    Bulgariu, Laura; Ratoi, Mioara; Bulgariu, Dumitru; Macoveanu, Matei

    2009-06-01

    This study was undertaken to evaluate the adsorption potential of Romanian peat moss for the removal of mercury(II) from aqueous solutions. The batch system experiments carried out showed that this natural material was effective in removing mercury(II). The analysis of FT-IR spectra indicated that the mechanism involved in the adsorption can be mainly attributed to the binding of mercury(II) with the carboxylic groups of Romanian peat moss. Adsorption equilibrium approached within 60 min. The adsorption data fitted well the Langmuir isotherm model. The maximum adsorption capacity (qmax) was 98.94 mg g(-1). Pseudo-second-order kinetic model was applicable to the adsorption data. The thermodynamic parameters indicate that the adsorption process was spontaneous as the Gibbs free energy values were found to be negative (between -17.58 and -27.25 kJ mol(-1)) at the temperature range of 6-54 degrees C.

  12. Adsorption properties and gaseous mercury transformation rate of natural biofilm.

    PubMed

    Cheng, Jinping; Zhao, Wenchang; Liu, Yuanyuan; Wu, Cheng; Liu, Caie; Wang, Wenhua

    2008-11-01

    Biofilms were developed on glass microscope slides in a natural aquatic environment and their mercury adsorption properties were evaluated. Results demonstrated that the biofilms contained a large number of bacterial cells and associated extracellular polymers. Mercury forms detected in the biofilms were mainly bound to residual matter and organic acids. The adsorption processes could be described by a Langmuir isotherm. The optimum conditions for adsorption of mercury to natural biofilm were an ionic strength of 0.1 mol/L, pH 6 and an optimum adsorption time of 40 min. The transformation rate was 0.79 microg gaseous mercury per gram of biofilm.

  13. Dynamic adsorption of ammonia: apparatus, testing conditions, and adsorption capacities

    NASA Astrophysics Data System (ADS)

    Amid, Hooman; Mazé, Benoît; Flickinger, Michael C.; Pourdeyhimi, Behnam

    2017-04-01

    There is a growing need for adsorbents with high capacities for adsorption of toxic gas molecules. Methods and conditions to test these materials introduce large discrepancies and overestimates (~90%) in the reported literature. This study describes a simple apparatus utilizing hand-held inexpensive gas sensors for testing adsorbents and hybrid adsorbent materials, explains possible sources for the observed discrepancies based on how the measurements are made, and provides guidelines for accurate measurements of adsorption capacity. Ammonia was the model gas and Ammonasorb™ activated carbon was the model commercial adsorbent. Inlet ammonia concentration, residence time, adsorbent pre-treatment (baking) and humidity, affected the measured adsorption capacities. Results suggest that the time lag in gas detection sensors leads to overestimated capacities. Monitoring both inlet and outlet concentrations using two calibrated sensors solved this issue. There was a direct relationship between adsorption capacity and residence time and capacities were higher at higher inlet concentrations. The size of the adsorbent particles did not show a significant effect on adsorption breakthrough, and the apparatus was able to quantify how humidity reduced the adsorption capacity.

  14. Enhancement of elemental mercury adsorption by silver supported material.

    PubMed

    Khunphonoi, Rattabal; Khamdahsag, Pummarin; Chiarakorn, Siriluk; Grisdanurak, Nurak; Paerungruang, Adjana; Predapitakkun, Somrudee

    2015-06-01

    Mercury, generally found in natural gas, is extremely hazardous. Although average mercury levels are relatively low, they are further reduced to comply with future mercury regulations, which are stringent in order to avoid releasing to the environment. Herein, vapor mercury adsorption was therefore investigated using two kinds of supports, granular activated carbon (GAC) and titanium dioxide (TiO2). Both supports were impregnated by silver (5 and 15 wt.%), before testing against a commercial adsorbent (sulfur-impregnated activated carbon, SAC). The adsorption isotherm, kinetics, and its thermodynamics of mercury adsorption were reported. The results revealed that Langmuir isotherm provided a better fit to the experimental data. Pseudo second-order was applicable to describe adsorption kinetics. The higher uniform Ag dispersion was a key factor for the higher mercury uptake. TiO2 supported silver adsorbent showed higher mercury adsorption than the commercial one by approximately 2 times. Chemisorption of mercury onto silver active sites was confirmed by an amalgam formation found in the spent adsorbents.

  15. Mercury adsorption of modified mulberry twig chars in a simulated flue gas.

    PubMed

    Shu, Tong; Lu, Ping; He, Nan

    2013-05-01

    Mulberry twig chars were prepared by pyrolysis, steam activation and impregnation with H2O2, ZnCl2 and NaCl. Textural characteristics and surface functional groups were performed using nitrogen adsorption and FTIR, respectively. Mercury adsorption of different modified MT chars was investigated in a quartz fixed-bed absorber. The results indicated that steam activation and H2O2-impregnation can improve pore structure significantly and H2O2-impregnation and chloride-impregnation promote surface functional groups. However, chloride-impregnation has adverse effect on pore structure. Mercury adsorption capacities of impregnated MT chars with 10% or 30% H2O2 are 2.02 and 1.77 times of steam activated MT char, respectively. Mercury adsorption capacity of ZnCl2-impregnated MT char increase with increasing ZnCl2 content and is better than that of NaCl-impregnated MT char at the same chloride content. The modified MT char (MT873-A-Z5) prepared by steam activation following impregnation with 5% ZnCl2 exhibits a higher mercury adsorption capacity (29.55 μg g(-1)) than any other MT chars.

  16. Effects of chemical functional groups on elemental mercury adsorption on carbonaceous surfaces.

    PubMed

    Liu, Jing; Cheney, Marcos A; Wu, Fan; Li, Meng

    2011-02-15

    A systematic theoretical study using density functional theory is performed to provide molecular-level understanding of the effects of chemical functional groups on mercury adsorption on carbonaceous surfaces. The zigzag and armchair edges were used in modeling the carbonaceous surfaces to simulate different adsorption sites. The edge atoms on the upper side of the models are unsaturated to simulate active sites. All calculations (optimizations, energies, and frequencies) were made at B3PW91 density functional theory level, using RCEP60VDZ basis set for mercury and 6-31G(d) pople basis set for other atoms. The results indicate that the embedding of halogen atom can increase the activity of its neighboring site which in turn increases the adsorption capacity of the carbonaceous surface for Hg(0). The adsorption belongs to chemisorptions, which is in good agreement with the experimental results. For the effects of oxygen functional groups, lactone, carbonyl and semiquinone favor Hg(0) adsorption because they increase the neighboring site's activity for mercury adsorption. On the contrary, phenol and carboxyl functional groups show a physisorption of Hg(0), and reduce Hg capture. This result can explain the seemingly conflicting experimental results reported in the literature concerning the influence of oxygen functional groups on mercury adsorption on carbonaceous surface.

  17. ENTRAINED-FLOW ADSORPTION OF MERCURY USING ACTIVATED CARBON

    EPA Science Inventory

    Bench-scale experiments were conducted in a flow reactor to simulate entrained-flow capture of elemental mercury (Hg) by activated carbon. Adsorption of Hg by several commercial activated carbons was examined at different carbon-to-mercury (C:Hg) ratios (by weight) (600:1 - 29000...

  18. ELEMENTAL MERCURY ADSORPTION BY ACTIVATED CARBON TREATED WITH SULFURIC ACID

    EPA Science Inventory

    The paper gives results of a study of the adsorption of elemental mercury at 125 C by a sulfuric-acid (H2S04, 50% w/w/ solution)-treated carbon for the removal of mercury from flue gas. The pore structure of the sample was characterized by nitrogen (N2) at -196 C and the t-plot m...

  19. ELEMENTAL MERCURY ADSORPTION BY ACTIVATED CARBON TREATED WITH SULFURIC ACID

    EPA Science Inventory

    The paper gives results of a study of the adsorption of elemental mercury at 125 C by a sulfuric-acid (H2S04, 50% w/w/ solution)-treated carbon for the removal of mercury from flue gas. The pore structure of the sample was characterized by nitrogen (N2) at -196 C and the t-plot m...

  20. Use of adsorption process to remove organic mercury thimerosal from industrial process wastewater.

    PubMed

    Velicu, Magdalena; Fu, Hongxiang; Suri, Rominder P S; Woods, Kevin

    2007-09-30

    Carbon adsorption process is tested for removal of high concentration of organic mercury (thimerosal) from industrial process wastewater, in batch and continuously flow through column systems. The organic mercury concentration in the process wastewater is about 1123 mg/L due to the thimerosal compound. Four commercially available adsorbents are tested for mercury removal and they are: Calgon F-400 granular activated carbon (GAC), CB II GAC, Mersorb GAC and an ion-exchange resin Amberlite GT73. The adsorption capacity of each adsorbent is described by the Freundlich isotherm model at pH 3.0, 9.5 and 11.0 in batch isotherm experiments. Acidic pH was favorable for thimerosal adsorption onto the GACs. Columns-in-series experiments are conducted with 30-180 min empty bed contact times (EBCTs). Mercury breakthrough of 30 mg/L occurred after about 47 h (96 Bed Volume Fed (BVF)) of operation, and 97 h (197 BVF) with 120 min EBCT and 180 min EBCT, respectively. Most of the mercury removal is attributed to the 1st adsorbent column. Increase in contact time by additional adsorbent columns did not lower the effluent mercury concentration below 30 mg/L. However, at a lower influent wastewater pH 3, the mercury effluent concentration decreased to less than 7 mg/L for up to 90 h of column operation (183 BVF).

  1. Kinetic studies of elemental mercury adsorption in activated carbon fixed bed reactor.

    PubMed

    Skodras, G; Diamantopoulou, Ir; Pantoleontos, G; Sakellaropoulos, G P

    2008-10-01

    Activated carbons are suitable materials for Hg(0) adsorption in fixed bed operation or in injection process. The fixed bed tests provide good indication of activated carbons effectiveness and service lives, which depend on the rates of Hg(0) adsorption. In order to correlate fixed bed properties and operation conditions, with their adsorptive capacity and saturation time, Hg(0) adsorption tests were realized in a bench-scale unit, consisted of F400 activated carbon fixed bed reactor. Hg(0) adsorption tests were conducted at 50 degrees C, under 0.1 and 0.35 ng/cm(3) Hg(0) initial concentrations and with carbon particle sizes ranging between 75-106 and 150-250 microm. Based on the experimental breakthrough data, kinetic studies were performed to investigate the mechanism of adsorption and the rate controlling steps. Kinetic models evaluated include the Fick's intraparticle diffusion equation, the pseudo-first order model, the pseudo-second order model and Elovich kinetic equation. The obtained experimental results revealed that the increase in particle size resulted in significant decrease of breakthrough time and mercury adsorptive capacity, due to the enhanced internal diffusion limitations and smaller external mass transfer coefficients. Additionally, higher initial mercury concentrations resulted in increased breakthrough time and mercury uptake. From the kinetic studies results it was observed that all the examined models describes efficiently Hg(0) breakthrough curves, from breakpoint up to equilibrium time. The most accurate prediction of the experimental data was achieved by second order model, indicating that the chemisorption rate seems to be the controlling step in the procedure. However, the successful attempt to describe mercury uptake with Fick's diffusion model and the first order kinetic model, reveals that the adsorption mechanism studied was complex and followed both surface adsorption and particle diffusion.

  2. Evidence of the direct adsorption of mercury in human hair during occupational exposure to mercury vapour.

    PubMed

    Queipo Abad, Silvia; Rodríguez-González, Pablo; García Alonso, J Ignacio

    2016-07-01

    We have found clear evidence of direct adsorption of mercury in human hair after the occupational exposure to mercury vapour. We have performed both longitudinal analysis of human hair by laser ablation ICP-MS and speciation analysis by gas chromatography ICP-MS in single hair strands of 5 individuals which were occupationally exposed to high levels of mercury vapour and showed acute mercury poisoning symptoms. Hair samples, between 3.5 and 11cm long depending on the individual, were taken ca. three months after exposure. Single point laser ablation samples of 50μm diameter were taken at 1mm intervals starting from the root of the hairs. Sulfur-34 was used as internal standard. The ratio (202)Hg/(34)S showed a distinct pattern of mercury concentration with much lower levels of mercury near the root of the hair and high levels of mercury near the end of the hair. In all cases a big jump in the concentration of mercury in hair occurred at a given distance from the root, between 32 and 42mm depending on the individual, with a high and almost constant concentration of mercury for longer distances to the root. When we took into account the rate of hair growth in humans, 9-15mm/month, the jump in mercury concentration agreed approximately with the dates when the contamination occurred with the new growing hair showing much lower mercury concentration. In some cases the concentration of mercury at the tip of the hair was ca. 1000 times higher than that near the root. Additionally, speciation studies confirmed that mercury in all hair samples was present as inorganic mercury. The only explanation for these results was the direct adsorption of mercury vapour in hair at the time of exposure. Copyright © 2016 Elsevier GmbH. All rights reserved.

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

    PubMed

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

    2017-06-01

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

  4. 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.

  5. Mechanisms of CPB Modified Zeolite on Mercury Adsorption in Simulated Wastewater.

    PubMed

    Liu, Jiang; Huang, Hui; Huang, Rong; Zhang, Jinzhong; Hao, Shuoshuo; Shen, Yuanyuan; Chen, Hong

    2016-06-01

    A systematic study was carried out to analyze the effects of mercury(II) adsorption by surface modified zeolite (SMZ) and adsorption mechanism. Cetylpyridinium bromide (CPB) was used to prepare SMZ. The characterization methods by means of powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM) showed that both the surface and internal zeolite were covered with CPB molecules, but the main binding sites were surface. Results showed that the organic carbon and cation exchange capacity of the SMZ were 7.76 times and 4.22 times higher than those of natural zeolite (NZ), respectively. Zeta potentials before and after modification were measured at -7.80 mV and -30.27 mV, respectively. Moreover, the saturation adsorptive capacity of SMZ was 16.35 times higher than NZ in mercury-containing wastewater. The possible mechanisms of mercury elimination were surface adsorption, hydrophobic interaction, ion exchange, electricity neutralization. The adsorption process was affected little by competitive ions.

  6. Adsorption of mercury from water by modified multi-walled carbon nanotubes: adsorption behaviour and interference resistance by coexisting anions.

    PubMed

    Chen, Paris Honglay; Hsu, Cheng-Feng; Tsai, David Dah-wei; Lu, Yen-Ming; Huang, Winn-Jung

    2014-08-01

    This investigation reports the use of modified multi-walled carbon nanotubes (MWCNTs) with various functional groups for adsorbing inorganic divalent mercury (Hg(II)) from water samples. To elucidate the behaviours and mechanisms of Hg(II) adsorption by modified MWCNTs, their adsorption capacity was studied by considering adsorption isotherms and kinetics. Particular attention was paid to interference of coexisting inorganic ions with Hg(II) adsorption. The results reveal that functionalization with oxygen-containing groups improved the Hg(II) adsorption capacity of the MWCNTs. Kinetic analysis demonstrated that the adsorption of Hg(II) by MWCNTs was closely described by the pseudo-second-order and Elovich models, suggesting that the adsorption of Hg(II) by MWCNTs was significantly affected by chemical adsorption. The kinetic results were also analysed using the intraparticle diffusion model, which revealed that intraparticle diffusion was not the only rate-controlling mechanism. The adsorption of Hg(II) on MWCNTs fell drastically as the ionic strength increased from 0 to 1.0mol/L chloride ions, and declined significantly as the pH increased from 2.2 to 10.5. The elemental maps obtained by energy-dispersive spectrometer (EDS) revealed the formation of surface complexes of chloride ions with functional groups on MWCNTs, which reduced the number of available sites for the adsorption of Hg(II) and strengthened the repulsive forces between Hg(II) and MWCNTs. The EDS results suggest that chloride ions are important in controlling Hg(II) speciation and adsorption on the surfaces of MWCNTs.

  7. Gas adsorption capacity of wood pellets

    DOE PAGES

    Yazdanpanah, F.; Sokhansanj, Shahabaddine; Lim, C. Jim; ...

    2016-02-03

    In this paper, temperature-programmed desorption (TPD) analysis was used to measure and analyze the adsorption of off-gases and oxygen by wood pellets during storage. Such information on how these gases interact with the material helps in the understanding of the purging/stripping behavior of off-gases to develop effective ventilation strategies for wood pellets. Steam-exploded pellets showed the lowest carbon dioxide (CO2) uptake compared to the regular and torrefied pellets. The high CO2 adsorption capacity of the torrefied pellets could be attributed to their porous structure and therefore greater available surface area. Quantifying the uptake of carbon monoxide by pellets was challengingmore » due to chemical adsorption, which formed a strong bond between the material and carbon monoxide. The estimated energy of desorption for CO (97.8 kJ/mol) was very high relative to that for CO2 (7.24 kJ/mol), demonstrating the mechanism of chemical adsorption and physical adsorption for CO and CO2, respectively. As for oxygen, the strong bonds that formed between the material and oxygen verified the existence of chemical adsorption and formation of an intermediate material.« less

  8. Gas adsorption capacity of wood pellets

    SciTech Connect

    Yazdanpanah, F.; Sokhansanj, Shahabaddine; Lim, C. Jim; Lau, A.; Bi, X. T.

    2016-02-03

    In this paper, temperature-programmed desorption (TPD) analysis was used to measure and analyze the adsorption of off-gases and oxygen by wood pellets during storage. Such information on how these gases interact with the material helps in the understanding of the purging/stripping behavior of off-gases to develop effective ventilation strategies for wood pellets. Steam-exploded pellets showed the lowest carbon dioxide (CO2) uptake compared to the regular and torrefied pellets. The high CO2 adsorption capacity of the torrefied pellets could be attributed to their porous structure and therefore greater available surface area. Quantifying the uptake of carbon monoxide by pellets was challenging due to chemical adsorption, which formed a strong bond between the material and carbon monoxide. The estimated energy of desorption for CO (97.8 kJ/mol) was very high relative to that for CO2 (7.24 kJ/mol), demonstrating the mechanism of chemical adsorption and physical adsorption for CO and CO2, respectively. As for oxygen, the strong bonds that formed between the material and oxygen verified the existence of chemical adsorption and formation of an intermediate material.

  9. Adsorption of elemental mercury vapors from synthetic exhaust combustion gas onto HGR carbon.

    PubMed

    Musmarra, D; Karatza, D; Lancia, A; Prisciandaro, M; Mazziotti di Celso, G

    2016-07-01

    An activated carbon commercially available named HGR, produced by Calgon-Carbon Group, was used to adsorbe metallic mercury. The work is part of a wider research activity by the same group focused on the removal of metallic and divalent mercury from combustion flue gas. With respect to previously published papers, this one is aimed at studying in depth thermodynamic equilibria of metallic mercury adsorption onto a commercial activated carbon. The innovativeness lies in the wider operative conditions explored (temperature and mercury concentrations) and in the evaluation of kinetic and thermodynamic data for a commercially available adsorbing material. In detail, experimental runs were carried out on a laboratory-scale plant, in which Hg° vapors were supplied in a nitrogen gas stream at different temperature and mercury concentration. The gas phase was flowed through a fixed bed of adsorbent material. Adsorbate loading curves for different Hg° concentrations together with adsorption isotherms were achieved as a function of temperature (120, 150, 200°C) and Hg° concentrations (1.0-7.0 mg/m(3)). Experimental runs demonstrated satisfying results of the adsorption process, while Langmuir parameters were evaluated with gas-solid equilibrium data. Especially, they confirmed that adsorption capacity is a favored process in case of lower temperature and they showed that the adsorption heat was -20 kJ/mol. Furthermore, a numerical integration of differential equations that model the adsorption process was proposed. Scanning electron microscopy (SEM) investigation was an useful tool to investigate about fresh and saturated carbon areas. The comparison between them allowed identification of surface sites where mercury is adsorbed; these spots correspond to carbon areas where sulfur concentration is greater. Mercury compounds can cause severe harm to human health and to the ecosystem. There are a lot of sources that emit mercury species to the atmosphere; the main ones are

  10. Thiol-ethylene bridged PMO: A high capacity regenerable mercury adsorbent via intrapore mercury thiolate crystal formation.

    PubMed

    Esquivel, Dolores; Ouwehand, Judith; Meledina, Maria; Turner, Stuart; Tendeloo, Gustaaf Van; Romero-Salguero, Francisco J; Clercq, Jeriffa De; Voort, Pascal Van Der

    2017-10-05

    Highly ordered thiol-ethylene bridged Periodic Mesoporous Organosilicas were synthesized directly from a homemade thiol-functionalized bis-silane precursor. These high surface area materials contain up to 4.3mmol/g sulfur functions in the walls and can adsorb up to 1183mg/g mercury ions. Raman spectroscopy reveals the existence of thiol and disulfide moieties. These groups have been evaluated by a combination of Raman spectroscopy, Ellman's reagent and elemental analysis. The adsorption of mercury ions was evidenced by different techniques, including Raman, XPS and porosimetry, which indicate that thiol groups are highly accessible to mercury. Scanning transmission electron microscopy combined with EDX showed an even homogenous distribution of the sulfur atoms throughout the structure, and have revealed for the first time that a fraction of the adsorbed mercury is forming thiolate nanocrystals in the pores. The adsorbent is highly selective for mercury and can be regenerated and reused multiple times, maintaining its structure and functionalities and showing only a marginal loss of adsorption capacity after several runs. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Mercury adsorption to gold nanoparticle and thin film surfaces

    NASA Astrophysics Data System (ADS)

    Morris, Todd Ashley

    Mercury adsorption to gold nanoparticle and thin film surfaces was monitored by spectroscopic techniques. Adsorption of elemental mercury to colloidal gold nanoparticles causes a color change from wine-red to orange that was quantified by UV-Vis absorption spectroscopy. The wavelength of the surface plasmon mode of 5, 12, and 31 nm gold particles blue-shifts 17, 14, and 7.5 nm, respectively, after a saturation exposure of mercury vapor. Colorimetric detection of inorganic mercury was demonstrated by employing 2.5 nm gold nanoparticles. The addition of low microgram quantities of Hg 2+ to these nanoparticles induces a color change from yellow to peach or blue. It is postulated that Hg2+ is reduced to elemental mercury by SCN- before and/or during adsorption to the nanoparticle surface. It has been demonstrated that surface plasmon resonance spectroscopy (SPRS) is sensitive to mercury adsorption to gold and silver surfaces. By monitoring the maximum change in reflectivity as a function of amount of mercury adsorbed to the surface, 50 nm Ag films were shown to be 2--3 times more sensitive than 50 nm Au films and bimetallic 15 nm Au/35 nm Ag films. In addition, a surface coverage of ˜40 ng Hg/cm2 on the gold surface results in a 0.03° decrease in the SPR angle of minimum reflectivity. SPRS was employed to follow Hg exposure to self-assembled monolayers (SAMs) on Au. The data indicate that the hydrophilic or hydrophobic character of the SAM has a significant effect on the efficiency of Hg penetration. Water adsorbed to carboxylic acid end group of the hydrophilic SAMs is believed to slow the penetration of Hg compared to methyl terminated SAMs. Finally, two protocols were followed to remove mercury from gold films: immersion in concentrated nitric acid and thermal annealing up to 200°C. The latter protocol is preferred because it removes all of the adsorbed mercury from the gold surface and does not affect the morphology of the gold surface.

  12. Equilibrium, kinetic and thermodynamic studies of mercury adsorption on almond shell.

    PubMed

    Khaloo, Shokooh Sadat; Matin, Amir Hossein; Sharifi, Sahar; Fadaeinia, Masoumeh; Kazempour, Narges; Mirzadeh, Shaghayegh

    2012-01-01

    The application of almond shell as a low cost natural adsorbent to remove Hg(2+) from aqueous solution was investigated. Batch experiments were carried out to evaluate the adsorption capacity of the material. The chemical and physical parameters such as pH, sorbent amount, initial ion concentration, and contact time were optimized for the maximum uptake of mercury onto the solid surface. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models, and the experimental data were found to fit the Langmuir model rather than the Freundlich. The maximum adsorption capacity obtained from the Langmuir isotherm was 135.13 mg/g. A kinetic study was carried out with pseudo-first-order and pseudo-second-order reaction equations and it was found that the Hg(2+) uptake process followed the pseudo-second-order rate expression. The thermodynamic values, ΔG(0), ΔH(0) and ΔS(0), indicated that adsorption was an endothermic and spontaneous process. The potential of this material for mercury elimination was demonstrated by efficient Hg(2+) removal from a synthetic effluent.

  13. Adsorption of mercury in coal-fired power plants gypsum slurry on TiO2/chitosan composite material

    NASA Astrophysics Data System (ADS)

    Gao, P.; Gao, B. B.; Gao, J. Q.; Zhang, K.; Chen, Y. J.; Yang, Y. P.; Chen, H. W.

    2016-07-01

    In this study, a simple method was used to prepare a chitosan adsorbent to mix with KI and TiO2. Gravimetric analysis (TG), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the samples before and after adsorption of Hg2+. A mercury adsorption experiment was also conducted in the gypsum slurry. The results show that using hydrobromic acid as a solvent of adsorbent resulted in a better adsorption effect than using acetic acid alone. Also, the sample (CS-KI/TiO2-HBr) had a maximum mercury adsorption capacity when the pH=5 and the t=50°C. The characterization experiments showed that the thermal stability of composite materials declined and the TiO2 uniformly dispersed in the surface of the samples with a lamellar structure, generating a lot of cracks and recesses that increased the reactive sites. Furthermore, when the TiO2 reacted with CS, it resulted in Ti-C, Ti-O and Ti-N bonds. The Br- can prevent the growth of TiO2 crystal grains and strengthen the ability of I- to remove mercury. The adsorption isotherm and kinetic results indicated that the adsorption behaviour of CS-KI/TiO2-HBr as it removes Hg2+ is an inhomogeneous multilayer adsorption process. The surface adsorption and intraparticle diffusion effects are both important in the Hg2+ adsorption process.

  14. Development of coconut pith chars towards high elemental mercury adsorption performance - Effect of pyrolysis temperatures.

    PubMed

    Johari, Khairiraihanna; Saman, Norasikin; Song, Shiow Tien; Cheu, Siew Chin; Kong, Helen; Mat, Hanapi

    2016-08-01

    In this study, chars from coconut pith (CP) were prepared aiming for superior adsorption towards elemental mercury (Hg(o)). The yield, proximate analysis, textural characteristics, surface functional groups and elemental composition analyses of the chars produced at pyrolysis temperature of 300 °C, 500 °C, 700 °C and 900 °C were compared. The surface area, pore volume, ash and carbon content of chars increased, while the yield and moisture content decreased with increasing pyrolysis temperatures. The changing of physical and chemical properties of the chars produced at variety pyrolysis temperature was much effect on the Hg(o) adsorption performance and definitely provides important information on the Hg(o) adsorption mechanism. The highest Hg(o) adsorption capacity was observed for CP900 (6067.49 μg/g), followed by CP700 (2395.98 μg/g), CP500 (289.76 μg/g), CP300 (1.68 μg/g), and CP (0.73 μg/g). The equilibrium data were well described by the Freundlich adsorption isotherm model. The pseudo-second order best described the kinetic data of the Hg(o) adsorption onto CP and CP300. For chars produced at higher pyrolysis temperature, however, the pseudo-zero order and pseudo-second order fitted well for the adsorption and breakthrough regions, respectively. The Hg(o) adsorption capacity of chars obtained from high pyrolysis temperature of CP significantly outperformed the commercial activated carbon (Darco KB-B) as well as superior to chars reported in the literature indicating the CP can be used as a precursor for preparation of chars as elemental mercury adsorbents.

  15. Enhanced and selective adsorption of mercury ions on chitosan beads grafted with polyacrylamide via surface-initiated atom transfer radical polymerization.

    PubMed

    Li, Nan; Bai, Renbi; Liu, Changkun

    2005-12-06

    Enhanced and selective removal of mercury ions was achieved with chitosan beads grafted with polyacrylamide (chitosan-g-polyacrylamide) via surface-initiated atom transfer radical polymerization (ATRP). The chitosan-g-polyacrylamide beads were found to have significantly greater adsorption capacities and faster adsorption kinetics for mercury ions than the chitosan beads. At pH 4 and with initial mercury concentrations of 10-200 mg/L, the chitosan-g-polyacrylamide beads can achieve a maximum adsorption capacity of up to 322.6 mg/g (in comparison with 181.8 mg/g for the chitosan beads) and displayed a short adsorption equilibrium time of less than 60 min (compared to more than 15 h for the chitosan beads). Coadsorption experiments with both mercury and lead ions showed that the chitosan-g-polyacrylamide beads had excellent selectivity in the adsorption of mercury ions over lead ions at pH < 6, in contrast to the chitosan beads, which did not show clear selectivity for either of the two metal species. Mechanism study suggested that the enhanced mercury adsorption was due to the many amide groups grafted onto the surfaces of the beads, and the selectivity in mercury adsorption can be attributed to the ability of mercury ions to form covalent bonds with the amide. It was found that adsorbed mercury ions on the chitosan-g-polyacrylamide beads can be effectively desorbed in a perchloric acid solution, and the regenerated beads can be reused almost without any loss of adsorption capacity.

  16. Influence of the pore structure and surface chemical properties of activated carbon on the adsorption of mercury from aqueous solutions.

    PubMed

    Lu, Xincheng; Jiang, Jianchun; Sun, Kang; Wang, Jinbiao; Zhang, Yanping

    2014-01-15

    Reactivation and chemical modification were used to obtain modified activated carbons with different pore structure and surface chemical properties. The samples were characterized by nitrogen absorption-desorption, Fourier transform infrared spectroscopy and the Bothem method. Using mercury chloride as the target pollutant, the Hg(2+) adsorption ability of samples was investigated. The results show that the Hg(2+) adsorption capacity of samples increased significantly with increases in micropores and acidic functional groups and that the adsorption process was exothermic. Different models and thermodynamic parameters were evaluated to establish the mechanisms. It was concluded that the adsorption occurred through a monolayer mechanism by a two-speed process involving both rapid adsorption and slow adsorption. The adsorption rate was determined by chemical reaction.

  17. Adsorption energies of mercury-containing species on CaO and temperature effects on equilibrium constants predicted by density functional theory calculations.

    PubMed

    Kim, Bo Gyeong; Li, Xinxin; Blowers, Paul

    2009-03-03

    The adsorption of Hg, HgCl, and HgCl2 on the CaO surface was investigated theoretically so the fundamental interactions between Hg species and this potential sorbent can be explored. Surface models of a 4 x 4 x 2 cluster, a 5 x 5 x 2 cluster, and a periodic structure using density functional theory calculations with LDA/PWC and GGA/BLYP functionals, as employed in the present work, offer a useful description for the thermodynamic properties of adsorption on metal oxides. The effect of temperature on the equilibrium constant for the adsorption of mercury-containing species on the CaO (0 0 1) surface was investigated with GGA/BLYP calculations in the temperature range of 250-600 K. Results show that, at low coverage of elemental mercury, adsorption on the surface is physisorption while the two forms of oxidized mercury adsorption undergo stronger adsorption. The adsorption energies decrease with increasing coverage for elemental mercury on the surfaces. The chlorine atom enhances the adsorption capacity and adsorbs mercury to the CaO surface more strongly. The adsorption energy is changed as the oxidation state varies, and the equilibrium constant decreases as the temperature increases, in good agreement with data for exothermic adsorption systems.

  18. Thorough removal of inorganic and organic mercury from aqueous solutions by adsorption on Lemna minor powder.

    PubMed

    Li, Shun-Xing; Zheng, Feng-Ying; Yang, Huang; Ni, Jian-Cong

    2011-02-15

    The adsorption ability of duckweed (Lemna minor) powders for removing inorganic and organic mercury (methyl and ethyl mercury) has been studied using cold vapour atomic absorption spectrometry. The optimal adsorption conditions were: (a) the pH value of the solution 7.0 for inorganic and ethyl mercury, 9.0 for methyl mercury, and (b) equilibrium adsorption time 10, 20, and 40 min for inorganic mercury, methyl mercury, and ethyl mercury, respectively. After adsorption by L. minor powder for 40 min, when the initial concentrations of inorganic and organic mercury were under 12.0 μg L(-1) and 50.0 μg L(-1), respectively, the residual concentrations of mercury could meet the criterion of drinking water (1.0 μg L(-1)) and the permitted discharge limit of wastewater (10.0 μg L(-1)) set by China and USEPA, respectively. Thorough removal of both inorganic and organic mercury from aqueous solutions was reported for the first time. The significant adsorption sites were C-O-P and phosphate groups by the surface electrostatic interactions with aqueous inorganic and organic mercury cations, and then the selective adsorption was resulted from the strong chelating interaction between amine groups and mercury on the surface of L. minor cells.

  19. Adsorption of mercury on laterite from Guizhou Province, China.

    PubMed

    Yu, Xiaohong; Zhu, Lijun; Guo, Baiwei; He, Shouyang

    2008-01-01

    The adsorption behaviors of Hg(II) on laterite from Guizhou Province, China, were studied and the adsorption mechanism was discussed. The results showed that different mineral compositons in the laterite will cause differences in the adsorption capacity of laterite to Hg(II). Illite and non-crystalloids are the main contributors to enhancing the adsorption capacity of laterite to Hg(II). The pH of the solution is an important factor affecting the adsorption of Hg(II) on laterite. The alkalescent environment (pH 7-9) is favorable to the adsorption of Hg(II). The amount of adsorbed Hg(II) increases with increasing pH. When the pH reaches a certain value, the amount of the adsorbed Hg(II) will reach the maximum level. The amount of adsorbed Hg(II) decreases with increasing pH. The optimal pHs of laterite and kaolinite are 9 and 8, respectively. The optimal initial concentrations of Hg(II) on laterite and kaolinite are 250 and 200 microg/ml, respectively. The adsorption isotherms were described by the Langmuir model. The adsorption of Hg(II) on laterite is a quick process while that of Hg(II) on kaolinite is a slow reaction. Laterite from Guizhou Province is a promising environmental material which can be used in the removal of Hg(II) from wastewater.

  20. Mercury adsorption on granular activated carbon in aqueous solutions containing nitrates and chlorides.

    PubMed

    Di Natale, F; Erto, A; Lancia, A; Musmarra, D

    2011-09-15

    Adsorption is an effective process to remove mercury from polluted waters. In spite of the great number of experiments on this subject, the assessment of the optimal working conditions for industrial processes is suffering the lack of reliable models to describe the main adsorption mechanisms. This paper presents a critical analysis of mercury adsorption on an activated carbon, based on the use of chemical speciation analysis to find out correlations between mercury adsorption and concentration of dissolved species. To support this analysis, a comprehensive experimental study on mercury adsorption at different mercury concentrations, temperatures and pH was carried out in model aqueous solutions. This study pointed out that mercury capture occurs mainly through adsorption of cationic species, the adsorption of anions being significant only for basic pH. Furthermore, it was shown that HgOH(+) and Hg(2+) are captured to a higher extent than HgCl(+), but their adsorption is more sensitive to solution pH. Tests on the effect of temperature in a range from 10 to 55 °C showed a peculiar non-monotonic trend for mercury solution containing chlorides. The chemical speciation and the assumption of adsorption exothermicity allow describing this experimental finding without considering the occurrence of different adsorption mechanisms at different temperature.

  1. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash.

    PubMed

    Liu, Minmin; Hou, Li-An; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-05-15

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and (29)Si and (27)Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin-Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics.

  2. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash

    NASA Astrophysics Data System (ADS)

    Liu, Minmin; Hou, Li-an; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-05-01

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin-Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics.

  3. Synthesis and characterization of gum acacia inspired silica hybrid xerogels for mercury(II) adsorption.

    PubMed

    Singh, Vandana; Singh, Somit Kumar

    2011-04-01

    In a sol-gel process, gum acacia inspired silica xerogels have been synthesized from tetraethylorthosilicate. Besides showing photoluminescence under ultraviolet excitation, the hybrid xerogels were very efficient in capturing mercury(II) from synthetic solution. To synthesize the optimum sample (in terms of Hg(II) uptake), different ratios of H(2)O:TEOS:EtOH were taken at fixed GA and catalyst concentrations where 4:1:1 ratio was found to be most favorable. Calcination in air further enhanced the mercury binding capacity of this sample. Optimum sample (H4) was obtained on calcination of the gel at 600°C. The hybrids have been structurally characterized using Infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermo gravimetric analysis, photoluminescence spectroscopy and Brunauer-Emmett-Teller analysis. In a preliminary batch adsorption experiment, H4 was evaluated to be highly efficient in the removal Hg(II) from synthetic aqueous solution.

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

    PubMed

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

    2017-08-01

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

  5. Characteristics and Stability of Mercury Vapor Adsorption over Two Kinds of Modified Semicoke

    PubMed Central

    Huawei, Zhang; Xiuli, Liu; Li, Wang; Peng, Liang

    2014-01-01

    In an attempt to produce effective and lower price gaseous Hg0 adsorbents, two methods of HCl and KMnO4/heat treatment were used respectively for the surface modification of liginite semicoke from inner Mongolia. The different effects of modification process on the surface physical and chemical properties were analyzed. The characteristics and stability of mercury vapor adsorption over two kinds of modified semicoke were investigated. The results indicated that modification process caused lower micropore quantity and volume capacity of semicoke; the C-Cl functional groups, C=O bond and delocalized electron π on the surface of Cl-SC, the amorphous higher valency Mnx+, and O=C–OH functional groups on the surface of Mn-H-SC were the active sites for oxidation and adsorption of gaseous Hg0. Modification process led to higher mercury removal efficiency of semicoke at 140°C and reduced the stability of adsorbed mercury of semicoke in simulated water circumstance simultaneously. PMID:25309948

  6. Characteristics and stability of mercury vapor adsorption over two kinds of modified semicoke.

    PubMed

    Huawei, Zhang; Xiuli, Liu; Li, Wang; Peng, Liang

    2014-01-01

    In an attempt to produce effective and lower price gaseous Hg(0) adsorbents, two methods of HCl and KMnO4/heat treatment were used respectively for the surface modification of liginite semicoke from inner Mongolia. The different effects of modification process on the surface physical and chemical properties were analyzed. The characteristics and stability of mercury vapor adsorption over two kinds of modified semicoke were investigated. The results indicated that modification process caused lower micropore quantity and volume capacity of semicoke; the C-Cl functional groups, C=O bond and delocalized electron π on the surface of Cl-SC, the amorphous higher valency Mn (x+) , and O=C-OH functional groups on the surface of Mn-H-SC were the active sites for oxidation and adsorption of gaseous Hg(0). Modification process led to higher mercury removal efficiency of semicoke at 140°C and reduced the stability of adsorbed mercury of semicoke in simulated water circumstance simultaneously.

  7. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash

    PubMed Central

    Liu, Minmin; Hou, Li-an; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-01-01

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin–Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics. PMID:23687400

  8. Adsorption behavior of mercury on functionalized aspergillus versicolor mycelia: atomic force microscopic study.

    PubMed

    Das, Sujoy K; Das, Akhil R; Guha, Arun K

    2009-01-06

    The adsorption characteristics of mercury on Aspergillus versicolor mycelia have been studied under varied environments. The mycelia are functionalized by carbon disulfide (CS(2)) treatment under alkaline conditions to examine the enhance uptake capacity and explore its potentiality in pollution control management. The functionalized A. versicolor mycelia have been characterized by scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDXA), attenuated total reflection infrared (ATR-IR), and atomic force microscopy (AFM) probing. SEM and AFM images exhibit the formation of nanoparticles on the mycelial surface. ATR-IR profile confirms the functionalization of the mycelia following chemical treatment. ATR-IR and EDXA results demonstrate the binding of the sulfur groups of the functionalized mycelia to the mercury and consequent formation metal sulfide. AFM study reveals that the mycelial surface is covered by a layer of densely packed domain like structures. Sectional analysis yields significant increase in average roughness (R(rms)) value (20.5 +/- 1.82 nm) compared to that of the pristine mycelia (4.56 +/- 0.82 nm). Surface rigidity (0.88 +/- 0.06 N/m) and elasticity (92.6 +/- 10.2 MPa) obtained from a force distance curve using finite element modeling are found to increase significantly with respect to the corresponding values of (0.65 +/- 0.05 N/m and 32.8 +/- 4.5 MPa) of the nonfunctionalized mycelia. The maximum mercury adsorption capacity of the functionalized mycelia is observed to be 256.5 mg/g in comparison to 80.71 mg/g for the pristine mycelia.

  9. Predicting protein dynamic binding capacity from batch adsorption tests.

    PubMed

    Carta, Giorgio

    2012-10-01

    The dynamic binding capacity (DBC) and its dependence on residence time influence the design and productivity of adsorption columns used in protein capture applications. This paper offers a very simple approach to predict the DBC of an adsorption column based on a measurement of the equilibrium binding capacity (EBC) and of the time needed to achieve one-half of the EBC in a batch adsorption test. The approach is based on a mass transfer kinetics model that assumes pore diffusion with a rectangular isotherm; however, the same approach is also shown to work for other systems where solute transport inside the particle occurs through other transport mechanisms.

  10. [Simulation study on the effect of salinity on the adsorption behavior of mercury in wastewater-irrigated area].

    PubMed

    Zheng, Shun-An; Li, Xiao-Hua; Xu, Zhi-Yu

    2014-05-01

    This study was designed to pinpoint the impact of salinity ( NaCl and Na2SO4, added at salinity levels of 0-5%, respectively) on the adsorption behavior of mercury in wastewater-irrigated areas of Tianjin City by batch and kinetic experiments. The results showed that, the Langmuir isotherm and the Elovich equation can well fitted batch and kinetic experimental data, respectively. As NaCI spiked in soil, Hg( II) adsorption capacity and strength had marked decreases, from 868.64 mgkg-1 and 1. 32 at control to 357.48 mgkg-1 and 0.63 at 5% salinity level of NaCI, respectively. As Na2SO4 spiked in soil, Hg(II) adsorption capacity (parameter qm in Langmuir isotherm) and strength (parameter k in Langmuir isotherm) changed slightly, from 868.64 mg kg-1 and 1.32 at control to 739.44 mg.kg-1 and 1. 18 at 5% salinity level of Na2 SO4, respectively. Kinetic data showed that, Hg( II) adsorption rate (parameter b in Elovich equation) in soil was not influenced by Na2SO, addition. However, the addition of NaC1 had a great effect on mercury adsorption rate. Hg(II ) adsorption capacity as a function of CI- or SO(2-)(4) content in soil could be simulated by the natural logarithm model, while Hg( II ) adsorption rate as a function of CI- content in soil could be simulated by the linear model. The study manifested that NaCI can significantly increase migration of Hg( II ) in the soil irrigated with wastewater, which may enhance Hg( II) bioavailability in the soil and cause a hazard to surface water. Especially, it will be harmful to human body through the food chain.

  11. Specific mercury(II) adsorption by thymine-based sorbent.

    PubMed

    Liu, Xiangjun; Qi, Cui; Bing, Tao; Cheng, Xiaohong; Shangguan, Dihua

    2009-04-15

    A new kind of polymer sorbent based on the specific interaction of Hg(II) with nucleic acid base, thymine, is described for the selective adsorption of Hg(II) from aqueous solution. Two types of sorbents immobilized with thymine were prepared by one-step swelling and polymerization and graft polymerization, respectively. The maximum static adsorption capacity of the new polymer sorbents for Hg(II) is proportional to the density of thymine on their surface, up to 200mg/g. Moreover, the new kind polymer sorbent shows excellent selectivity for Hg(II) over other interfering ions, such as Cu(II), Cd(II), Zn(II), Co(II), Ca(II) and Mg(II), exhibits very fast kinetics for Hg(II) adsorption from aqueous solution, and can be easily regenerated by 1.0M HCl. It also has been successfully used for the selective adsorption of spiked Hg(II) from real tap water samples. This new thymine polymer sorbent holds a great promise in laboratory and industrial applications such as separation, on-line enrichment, solid-phase extraction, and removal of Hg(II) from pharmaceutical, food and environmental samples.

  12. Optimization of a novel setup for an on-line study of elemental mercury adsorption by cold-vapor atomic absorption spectrometry.

    PubMed

    Assari, Mohammad Javad; Rezaee, Abbas; Jonidi Jafari, Ahmad; Bahrami, Abdolrahman

    2013-05-29

    The objective of this work was developing a simple and stable time-based on-line setup for assessing the potential of mercury (Hg) vapor adsorption of the commercial sorbents used in air sampling and control operation followed by cold vapor atomic absorption spectrometry (CVAAS). A special designed separation chamber was used where reduction of the injected Hg (II) solution took place. Purge gas passes through this chamber resulting to a prompt release of mercury vapor, purging into the adsorbent that regulated at the desired adsorption temperature. After sorbent saturation, in order to study the adsorption parameters of sorbents (activated carbon and bone char) such as breakthrough time (BTT), and adsorptive capacity, mercury gas stream was passed through the sorbents, directly transport to the CVAAS. Preliminary experiments concerning the reductant solution showed that SnCl2 offers higher stability than NaBH4. Around the loading range 0.125-2.5 ml min⁻¹ of 100 µg l⁻¹ Hg(II) solution, a linear calibration curve with the equation peak area=0.134; loading flow=-0.017 and a correlation coefficient r=0.996 was obtained, and the detection limit was improved up to c(L)=1 µg l⁻¹. The relative standard deviation of five measurements of lowest flow loading of Hg (II) was RSD=2.8%. The significant differences were observed in the breakthrough time and mercury adsorptive capacity between activated carbon and bone char (P=0.010). This novel setup is suitable for an on-line study of elemental mercury adsorption, determination of breakthrough time and adsorption capacity, and because of its stable performance during all experiments; it can be applied to the time based studies.

  13. Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed Reactor

    SciTech Connect

    Buitrago, Paula A.; Morrill, Mike; Lighty, JoAnn S.; Silcox, Geoffrey D.

    2009-06-15

    This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO2, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO2, and NO2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

  14. Evaluating the Adsorptive Capacities of Chemsorb 1000 and Chemsorb 1425

    NASA Technical Reports Server (NTRS)

    Monje, Oscar Alberto Monje; Surma, Jan M.; Johnsey, Marissa N.; Melendez, Orlando

    2014-01-01

    The Air Revitalization Lab at KSC tested Chemsorb 1000 and 1425, two candidate sorbents for use in future air revitalization technologies being evaluated by the ARREM project. Chemsorb 1000 and 1425 are granular coconut-shell activated carbon sorbents produced by Molecular Products, Inc. that may be used in the TCCS. Chemsorb 1000 is a high grade activated carbon for organic vapor adsorption. In contrast, Chemsorb 1425 is a high-grade impregnated activated carbon for adsorption of airborne ammonia and amines. Chemsorb 1000 was challenged with simulated spacecraft gas streams in order to determine its adsorptive capacities for mixtures of volatile organics compounds. Chemsorb 1425 was challenged with various NH3 concentrations to determine its adsorptive capacity.

  15. High capacity adsorption media and method of producing

    DOEpatents

    Tranter, Troy J.; Mann, Nicholas R.; Todd, Terry A.; Herbst, Ronald S.

    2010-10-05

    A method of producing an adsorption medium to remove at least one constituent from a feed stream. The method comprises dissolving and/or suspending at least one metal compound in a solvent to form a metal solution, dissolving polyacrylonitrile into the metal solution to form a PAN-metal solution, and depositing the PAN-metal solution into a quenching bath to produce the adsorption medium. The at least one constituent, such as arsenic, selenium, or antimony, is removed from the feed stream by passing the feed stream through the adsorption medium. An adsorption medium having an increased metal loading and increased capacity for arresting the at least one constituent to be removed is also disclosed. The adsorption medium includes a polyacrylonitrile matrix and at least one metal hydroxide incorporated into the polyacrylonitrile matrix.

  16. High capacity adsorption media and method of producing

    DOEpatents

    Tranter, Troy J [Idaho Falls, ID; Herbst, R Scott [Idaho Falls, ID; Mann, Nicholas R [Blackfoot, ID; Todd, Terry A [Aberdeen, ID

    2008-05-06

    A method of producing an adsorption medium to remove at least one constituent from a feed stream. The method comprises dissolving at least one metal compound in a solvent to form a metal solution, dissolving polyacrylonitrile into the metal solution to form a PAN-metal solution, and depositing the PAN-metal solution into a quenching bath to produce the adsorption medium. The at least one constituent, such as arsenic, selenium, or antimony, is removed from the feed stream by passing the feed stream through the adsorption medium. An adsorption medium having an increased metal loading and increased capacity for arresting the at least one constituent to be removed is also disclosed. The adsorption medium includes a polyacrylonitrile matrix and at least one metal hydroxide incorporated into the polyacrylonitrile matrix.

  17. Zearalenone adsorption capacity of lactic acid bacteria isolated from pigs.

    PubMed

    Vega, María F; Dieguez, Susana N; Riccio, Belén; Aranguren, Sandra; Giordano, Antonio; Denzoin, Laura; Soraci, Alejandro L; Tapia, María O; Ross, Romina; Apás, Ana; González, Silvia N

    The ability to adsorb zearalenone by five strain of lactic acid bacteria was evaluated: four strains of Lactobacillus spp. isolated from pig rectal swabs and one commercial strain (Lactobacillus rhamnosus). Several factors affecting the adsorption capacity were evaluated in order to improve the adsorption of the mycotoxin by bacteria. The stability of the zearalenone-bacteria complex was analyzed. In every case, bacterial adsorption capacity was higher than 40.0%. The strain showing the highest adsorption (68.2%) was selected for the following steps of this research. The adsorption percentages obtained after processing 6.5 and 7.5mL MRS broth were 57.40%+3.53 and 64.46%+0.76, respectively. The stability of zearalenone-bacteria complex was evaluated by successively rinsing. In the first rinsing step 42.26%+0.414 was still bound. In the second rinsing step 25.12%+0.664 was still bound, whereas 15.82%+0.675 remained in the pellet after the third rinse. Results obtained demonstrated that Lactic Acid Bacteria has capacity to adsorb zearalenone. Finally adsorption was increased using a higher volume of initial broth. These results could be used to design a new lyophilized powder for detoxification, using lactic acid bacteria as potential zearalenone adsorbents. Copyright © 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  18. An In Situ Surface Fourier Transform Infrared Study of the Adsorption of Isoquinoline at a Stationary Mercury Electrode

    DTIC Science & Technology

    1988-07-15

    Infrared Study of the Adsorption of Isoquinoline at a Stationary Mercury Electrode by DJ. Blackwood and S. Pons Prepared for publication in J...Secunt ClaMwfkation) An in situ Surface Fourier Transform Infrared Study of the Adsorption of Isoquinoline at a Stationary Mercury Electrode D.lc...SUBJECT TERMS (Continue on roverse if necessary and identify by block ’e’ 9ELD I GROUP I SUB-GROUP infrared spectroelectrochemistry ,adsorption, mercury I

  19. The adsorption of mercury(II) on the surface of silica modified with β-cyclodextrin

    NASA Astrophysics Data System (ADS)

    Belyakova, L. A.; Shvets, A. N.; Denil de Namor, A. F.

    2008-08-01

    Multistage chemical modification of the surface of silica with β-cyclodextrin was performed. IR spectroscopy and quantitative analysis of surface compounds were used to prove the structure of modified silica. The adsorption of Hg(II) from dilute solutions was studied. The adsorption affinity of silica for mercury ions increased because of the formation of supramolecular structures with chemically immobilized β-cyclodextrin.

  20. CHARACTERIZATION OF ACTIVATED CARBONS' PHYSICAL AND CHEMICAL PROPERTIES IN RELATION TO THEIR MERCURY ADSORPTION

    EPA Science Inventory

    The paper gives results of a characterization of the physical and chemical properties of the activated carbons used for elemental mercury (Hgo) adsorption, in order to understand the role of oxygen surface functional groups on the mechanism of Hgo adsorption by activated carbons....

  1. CHARACTERIZATION OF ACTIVATED CARBONS' PHYSICAL AND CHEMICAL PROPERTIES IN RELATION TO THEIR MERCURY ADSORPTION

    EPA Science Inventory

    The paper gives results of a characterization of the physical and chemical properties of the activated carbons used for elemental mercury (Hgo) adsorption, in order to understand the role of oxygen surface functional groups on the mechanism of Hgo adsorption by activated carbons....

  2. A study on the adsorption mechanism of mercury on Aspergillus versicolor biomass.

    PubMed

    Das, Sujoy K; Das, Akhil R; Guha, Arun K

    2007-12-15

    The adsorption behavior of mercury on Aspergillus versicolor biomass (AVB) has been investigated in aqueous solution to understand the physicochemical process involved and to explore the potentiality of AVB in pollution control management. This biomass has been successfully used for reducing the mercury concentration level in the effluent of chloralkali and battery industries to a permissible limit. The results establish that 75.6 mg of mercury is adsorbed per gram of biomass. The adsorption process is found to be a function of pH of the solution, with the optimum range being pH 5.0-6.0. The process obeys the Langmuir-Freundlich isotherm model. Scanning electron microscopic analysis demonstrates a conspicuous surface morphology change of the mercury-adsorbed biomass. A nearly uniform distribution of metal ions on the mycelial surface excepting a few aggregation points is revealed by X-ray elemental mapping profiles. The results of zeta potential measurement, Fourier transform infrared (FTIR) spectroscopy, and blocking of the functional groups by chemical modification reflect the binding of mercury on the biomass occurs through electrostatic and complexation reactions. The accumulation of mercury on the cell wall associated with negligible diffusion and or transportation into cytoplasm finds support from the results of adsorption kinetics and transmission electron micrographs. Mercury adsorption on biomass also leads to elongation of cells and cytoplasmic aggregation of spheroplast/protoplasts, indicating that the cell wall acts as a permeation barrier against this toxic metal.

  3. Simultaneous Removal of NOx and Mercury in Low Temperature Selective Catalytic and Adsorptive Reactor

    SciTech Connect

    Neville G. Pinto; Panagiotis G. Smirniotis

    2006-03-31

    The results of a 18-month investigation to advance the development of a novel Low Temperature Selective Catalytic and Adsorptive Reactor (LTSCAR), for the simultaneous removal of NO{sub x} and mercury (elemental and oxidized) from flue gases in a single unit operation located downstream of the particulate collectors, are reported. In the proposed LTSCAR, NO{sub x} removal is in a traditional SCR mode but at low temperature, and, uniquely, using carbon monoxide as a reductant. The concomitant capture of mercury in the unit is achieved through the incorporation of a novel chelating adsorbent. As conceptualized, the LTSCAR will be located downstream of the particulate collectors (flue gas temperature 140-160 C) and will be similar in structure to a conventional SCR. That is, it will have 3-4 beds that are loaded with catalyst and adsorbent allowing staged replacement of catalyst and adsorbent as required. Various Mn/TiO{sub 2} SCR catalysts were synthesized and evaluated for their ability to reduce NO at low temperature using CO as the reductant. It has been shown that with a suitably tailored catalyst more than 65% NO conversion with 100% N{sub 2} selectivity can be achieved, even at a high space velocity (SV) of 50,000 h-1 and in the presence of 2 v% H{sub 2}O. Three adsorbents for oxidized mercury were developed in this project with thermal stability in the required range. Based on detailed evaluations of their characteristics, the mercaptopropyltrimethoxysilane (MPTS) adsorbent was found to be most promising for the capture of oxidized mercury. This adsorbent has been shown to be thermally stable to 200 C. Fixed-bed evaluations in the targeted temperature range demonstrated effective removal of oxidized mercury from simulated flue gas at very high capacity ({approx}>58 mg Hg/g adsorbent). Extension of the capability of the adsorbent to elemental mercury capture was pursued with two independent approaches: incorporation of a novel nano-layer on the surface of the

  4. Evaluation of Fuller's earth for the adsorption of mercury from aqueous solutions: a comparative study with activated carbon.

    PubMed

    Oubagaranadin, John U Kennedy; Sathyamurthy, N; Murthy, Z V P

    2007-04-02

    Fuller's earth (FE) has been used as an adsorbent in this work to remove mercury from aqueous solutions. For the purpose of comparison, simultaneous experiments using activated carbon (AC) have also been done. The aim of the work is to test how best FE can be used as an adsorbent for mercury. Equilibrium isotherms, such as Freundlich, Langmuir, Dubinin-Redushkevich, Temkin, Harkins-Jura, Halsey and Henderson have been tested. Kinetic studies based on Lagergren first-order, pseudo-second-order rate expressions and intra-particle diffusion studies have been done. The batch experiments were conducted at room temperature (30 degrees C) and at the normal pH (6.7+/-0.2) of the solution. It has been observed that Hg(II) removal rate is better for FE than AC, due to large dosage requirement, whereas the adsorption capacity of AC is found to be much better than FE. Hence, although FE can be used as an adsorbent, a high dosage is required, when compared to AC. Hybrid fractional error function analysis shows that the best-fit for the adsorption equilibrium data is represented by Freundlich isotherm. Kinetic and film diffusion studies show that the adsorption of mercury on FE and AC is both intra-particle diffusion and film diffusion controlled.

  5. Surface functionalized nano-magnetic particles for wastewater treatment: adsorption and desorption of mercury.

    PubMed

    Tri, Pham Minh; Khim, Kwa Soo; Hidajat, K; Uddin, M S

    2009-02-01

    The present study deals with adsorption and desorption of mercury on surface functionalized nano-magnetic particles. The nano-magnetic particles (Fe3O4) were synthesized by chemical precipitation of Fe2+ and Fe3+ salts at 80 degrees C at alkaline condition and inert atmosphere. The particle surface was then functionalized in two different ways: surface charge controlled by solution pH and coating the surface with polymer (vinylpyrrolidone) with thiodiglycolic acid as the primary surfactant and 4-vinylaniline as the secondary surfactant. It was found that the adsorption of mercury was pH dependent and maximum adsorption occurred at pH of 7.5 with bare particles and at pH 10 for polymer grafted particles. Maximum adsorption of mercury was found to be 280 mg/g particle.

  6. Fabrication of a selective mercury sensor based on the adsorption of cold vapor of mercury on carbon nanotubes: determination of mercury in industrial wastewater.

    PubMed

    Safavi, Afsaneh; Maleki, Norouz; Doroodmand, Mohammad Mahdi

    2010-01-15

    A new sensor for the determination of mercury at microg ml(-1) levels is proposed based on the adsorption of mercury vapor on single-walled carbon nanotubes (SWCNTs). The changes in the impedance of SWCNTs were monitored upon adsorption of mercury vapor. The adsorption behaviour of mercury on SWCNTs was compared with that on multi-walled carbon nanotubes (MWCNTs) and carbon nanofibers (CNFs). Cold vapor of mercury was generated at 65 degrees C using Sn(II) solution as a reducing agent. The limit of detection was 0.64 microg ml(-1) for Hg(II) species. The calibration curve for Hg(II) was linear from 1.0 to 30.0 microg ml(-1). The relative standard deviation (RSD) of eight replicate analyses of 15 microg ml(-1) of Hg(II) was 2.7%. The results showed no interfering effects from many foreign species and hydride forming elements. The system was successfully applied to the determination of the mercury content of different types of wastewater samples.

  7. Enhancing the adsorption of vapor-phase mercury chloride with an innovative composite sulfur-impregnated activated carbon.

    PubMed

    Ie, Iau-Ren; Chen, Wei-Chin; Yuan, Chung-Shin; Hung, Chung-Hsuang; Lin, Yuan-Chung; Tsai, Hsieh-Hung; Jen, Yi-Shiu

    2012-05-30

    Mercury chloride (HgCl(2)) is the major mercury derivate emitted from municipal solid waste incinerators, which has high risk to the environment and human health. This study investigated the adsorption of vapor-phase HgCl(2) with an innovative composite sulfurized activated carbon (AC), which was derived from the pyrolysis, activation, and sulfurization of waste tires. The composite sulfur-impregnation process impregnated activated carbon with aqueous-phase sodium sulfide (Na(2)S) and followed with vapor-phase elemental sulfur (S(0)). Thermogravimetric analysis (TGA) was applied to investigate the adsorptive capacity of vapor-phase HgCl(2) using the composite sulfurized AC. The operating parameters included the types of composite sulfurized AC, the adsorption temperature, and the influent HgCl(2) concentration. Experimental results indicated that the sulfur-impregnation process could increase the sulfur content of the sulfurized AC, but decreased its specific surface area. This study further revealed that the composite sulfurized AC impregnated with aqueous-phase Na(2)S and followed with vapor-phase S(0) (Na(2)S+S(0) AC) had much higher saturated adsorptive capacity of HgCl(2) than AC impregnated in the reverse sequence (S(0)+Na(2)S AC). A maximum saturated adsorptive capacity of HgCl(2) up to 5236 μg-HgCl(2)/g-C was observed for the composite Na(2)S+S(0) AC, which was approximately 2.00 and 3.17 times higher than those for the single Na(2)S and S(0) ACs, respectively.

  8. Mechanistic studies of mercury adsorption and oxidation by oxygen over spinel-type MnFe2O4.

    PubMed

    Yang, Yingju; Liu, Jing; Zhang, Bingkai; Liu, Feng

    2017-01-05

    MnFe2O4 has been regarded as a very promising sorbent for mercury emission control in coal-fired power plants because of its high adsorption capacity, magnetic, recyclable and regenerable properties. First-principle calculations based on density functional theory (DFT) were used to elucidate the mercury adsorption and oxidation mechanisms on MnFe2O4 surface. DFT calculations show that Mn-terminated MnFe2O4 (1 0 0) surface is much more stable than Fe-terminated surface. Hg(0) is physically adsorbed on Fe-terminated MnFe2O4 (1 0 0) surface. Hg(0) adsorption on Mn-terminated MnFe2O4 (1 0 0) surface is a chemisorption process. The partial density of states (PDOS) analysis indicates that Hg atom interacts strongly with surface Mn atoms through the orbital hybridization. HgO is adsorbed on the MnFe2O4 surface in a chemical adsorption manner. The small HOMO-LUMO energy gap implies that HgO molecular shows high chemical reactivity for HgO adsorption on MnFe2O4 surface. The energy barriers of Hg(0) oxidation by oxygen on Fe- and Mn-terminated MnFe2O4 surfaces are 206.37 and 76.07kJ/mol, respectively. Mn-terminated surface is much more favorable for Hg(0) oxidation than Fe-terminated surface. In the whole Hg(0) oxidation process, the reaction between adsorbed mercury and surface oxygen is the rate-determining step.

  9. Characteristic and mercury adsorption of activated carbon produced by CO2 of chicken waste.

    PubMed

    Huang, Yaji; Jin, Baosheng; Zhong, Zhaoping; Zhong, Wenqi; Xiao, Rui

    2008-01-01

    Preparation of activated carbon from chicken waste is a promising way to produce a useful adsorbent for Hg removal. A three-stage activation process (drying at 200 degrees C, pyrolysis in N2 atmosphere, followed by CO2 activation) was used for the production of activated samples. The effects of carbonization temperature (400-600 degrees C), activation temperature (700-900 degrees C), and activation time (1-2.5 h) on the physicochemical properties (weight-loss and BET surface) of the prepared carbon were investigated. Adsorptive removal of mercury from real flue gas onto activated carbon has been studied. The activated carbon from chicken waste has the same mercury capacity as commercial activated carbon (Darco LH) (Hg(v): 38.7% vs. 53.5%, Hg(0): 50.5% vs. 68.8%), although its surface area is around 10 times smaller, 89.5 m2/g vs. 862 m2/g. The low cost activated carbon can be produced from chicken waste, and the procedure is suitable.

  10. Mercury oxidation and adsorption characteristics of potassium permanganate modified lignite semi-coke.

    PubMed

    Zhang, Huawei; Chen, Jitao; Liang, Peng; Wang, Li

    2012-01-01

    The adsorption characteristics of virgin and potassium permanganate modified lignite semi-coke (SC) for gaseous Hg0 were investigated in an attempt to produce more effective and lower price adsorbents for the control of elemental mercury emission. Brunauer-Emmett-Teller (BET) measurements, X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to analyze the surface physical and chemical properties of SC, Mn-SC and Mn-H-SC before and after mercury adsorption. The results indicated that potassium permanganate modification had significant influence on the properties of semi-coke, such as the specific surface area, pore structure and surface chemical functional groups. The mercury adsorption efficiency of modified semi-coke was lower than that of SC at low temperature, but much higher at high temperature. Amorphous Mn7+, Mn6+ and Mn4+ on the surface of Mn-SC and Mn-H-SC were the active sites for oxidation and adsorption of gaseous Hg0, which oxidized the elemental mercury into Hg2+ and captured it. Thermal treatment reduced the average oxidation degree of Mn(x+) on the surface of Mn-SC from 3.80 to 3.46. However, due to the formation of amorphous MnOx, the surface oxidation active sites for gaseous Hg0 increased, which gave Mn-H-SC higher mercury adsorption efficiency than that of Mn-SC at high temperature.

  11. Theoretical Study of Mercury Species Adsorption on CaO(100) Surface

    NASA Astrophysics Data System (ADS)

    Zhang, Chong; Liu, Yu; Zhao, Li; Cui, Min-Shu; Lu, Qiang

    2017-05-01

    As an important air pollutant, mercury produced by power generation can be captured by CaO incoal-firedfly ash. In order to understand the interaction mechanism of CaO with mercury in HCl atmosphere, the density functional theory method is utilizedto investigate the adsorption of mercury species on the fly ash components. The CaO(100) surface is built to study the stable adsorption configurations of Hg0, HCl, HgCl and HgCl2 on all possible adsorption sites. The results show that CaO(100) surface cannot absorb Hg0 directly, but the intermediate HgCl can be adsorbed on the surface stably, and then continue to combine with a Cl radical to produce HgCl2, which is easy to be removed.

  12. Evaluation of the adsorption capacity of alkali-treated waste materials for the adsorption of sulphamethoxazole.

    PubMed

    Kurup, Lisha

    2012-01-01

    The present work is to develop potential adsorbents from waste material and employ them for the removal of a hazardous antibacterial, sulphamethoxazole, from the wastewater by the Adsorption technique. The Adsorption technique was used to impound the dangerous antibiotics from wastewater using Deoiled Soya (DOS), an agricultural waste, and Water Hyacinth (WH), a prolific colonizer. The adsorption capacity of these adsorbents was further enhanced by treating them with sodium hydroxide solution and it was seen that the adsorption capacity increases by 10 to 25%. Hence a comparative account of the adsorption studies of all the four adsorbents, i.e. DOS, Alkali-treated DOS, WH and Alkali-treated Water Hyacinth has been discussed in this paper. Different isotherms like Freundlich, Langmuir and Dubinin-Radushkevich were also deduced from the adsorption data. Isotherm studies were in turn used in estimating the thermodynamic parameters. DOS showed sorption capacity of 0.0007 mol g(-1) while Alkali-treated Deoiled Soya exhibited 0.0011 mol g(-1) of sorption capacity, which reveals that the adsorption is higher in case of alkali-treated adsorbent. The mean sorption energy (E) was obtained between 9 and 12 kJ mol, which shows that the reaction proceeds by ion exchange reaction. Kinetic study reveals that the reaction follows pseudo-second-order rate equation. Moreover, mass transfer studies performed for the ongoing processes show that the mass transfer coefficient obtained for alkali-treated moieties was higher than the parent moieties. The breakthrough curves plotted from the column studies show percentage saturation of 90-98%. About 87-97% of sulphamethoxazole was recovered from column by desorption.

  13. Multifractal analysis of soil porosity based on mercury porosimetry and nitrogen adsorption

    NASA Astrophysics Data System (ADS)

    Paz-Ferreiro, J.; Vidal Vázquez, E.; Miranda, J. G. V.

    2009-04-01

    The soil pore space is composed of a continuum of pores extremely variable in size which include structures smaller than nanometres and as large as macropores > 20 mm in diameter, i.e. with an upper size limit of the order of centimetres. Thus, a ratio of at least 106 is displayed in soil pore sizes. Soil pore size distribution directly influences many soil physical, chemical and biological properties. Characterization of soil structure may be achieved by pore size distribution analysis. There is not a unique method for determining soil pore size distributions all over the size scale. Mercury injection porosimetry and N2 adsorption isotherms are techniques commonly used for assessing equivalent pore size diameters in selected ranges. The Hg injection technique provides pore size distributions in the range from about 50 nm to 100 m, whereas N2 adsorption isotherms may be used for finer pores ranging in size from about 2 to 500 nm. In this work, multifractal formalism has been used to describe Hg injection porosimetry and N2 adsorption isotherms measured in a Mollisol and in a Vertisol with four different soil use intensities, ranging from native, never cultivated, land to continuous cropping. Three samples per treatment were analyzed resulting in a total of twelve samples per soil. All the Hg injection curves and N2 adsorption isotherms exhibited multifractal behaviour as shown by singularity spectra and Rényi dimension spectra. The capacity dimension, D0, for both Hg injection and N2 adsorption data sets was not significantly different from 1.00. However, significantly different values of entropy dimension, D1, and correlation dimension, D2, were obtained for mercury injection and nitrogen adsorption experimental data. For instance, entropy dimension, D1, values extracted from multifractal spectra of Hg intrusion porosimetry were on average 0.913 and varied from 0.889 to 0.939. However, the corresponding figures for N2 adsorption isotherms were on average 0

  14. Adsorption of toxic mercury(II) by an extracellular biopolymer poly(gamma-glutamic acid).

    PubMed

    Inbaraj, B Stephen; Wang, J S; Lu, J F; Siao, F Y; Chen, B H

    2009-01-01

    Adsorption of mercury(II) by an extracellular biopolymer, poly(gamma-glutamic acid) (gamma-PGA), was studied as a function of pH, temperature, agitation time, ionic strength, light and heavy metal ions. An appreciable adsorption occurred at pH>3 and reached a maximum at pH 6. Isotherms were well predicted by Redlich-Peterson model with a dominating Freundlich behavior, implying the heterogeneous nature of mercury(II) adsorption. The adsorption followed an exothermic and spontaneous process with increased orderliness at solid/solution interface. The adsorption was rapid with 90% being attained within 5 min for a 80 mg/L mercury(II) solution, and the kinetic data were precisely described by pseudo second order model. Ionic strength due to added sodium salts reduced the mercury(II) binding with the coordinating ligands following the order: Cl(-) >SO(4)(2-) >NO(3)(-). Both light and heavy metal ions decreased mercury(II) binding by gamma-PGA, with calcium(II) ions showing a more pronounced effect than monovalent sodium and potassium ions, while the interfering heavy metal ions followed the order: Cu(2+) > Cd(2+) > Zn(2+). Distilled water adjusted to pH 2 using hydrochloric acid recovered 98.8% of mercury(II), and gamma-PGA reuse for five cycles of operation showed a loss of only 6.5%. IR spectra of gamma-PGA and Hg(II)-gamma-PGA revealed binding of mercury(II) with carboxylate and amide groups on gamma-PGA.

  15. Mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor.

    PubMed

    Zhang, Yongsheng; Zhao, Lilin; Guo, Ruitao; Song, Na; Wang, Jiawei; Cao, Yan; Orndorff, William; Pan, Wei-ping

    2015-07-01

    In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performance of the HBr-modified fly ash was enhanced significantly. The mercury species adsorbed by unmodified fly ash were HgCl2, HgS and HgO. The mercury adsorbed by HBr-modified fly ash, in the entrained-flow reactor, existed in two forms, HgBr2 and HgO, and the HBr was the dominant factor promoting oxidation of elemental mercury in the entrained-flow reactor. In the current study, the concentration of HgBr2 and HgO in ash from the fine ash vessel was 4.6 times greater than for ash from the coarse ash vessel. The fine ash had better mercury adsorption performance than coarse ash, which is most likely due to the higher specific surface area and longer residence time. Copyright © 2015. Published by Elsevier B.V.

  16. Silver impregnated carbon for adsorption and desorption of elemental mercury vapors.

    PubMed

    Karatza, Despina; Prisciandaro, Marina; Lancia, Amedeo; Musmarra, Dino

    2011-01-01

    The Hg(0) vapor adsorption experimental results on a novel sorbent obtained by impregnating a commercially available activated carbon (Darco G60 from BDH) with silver nitrate were reported. The study was performed by using a fundamental approach, in an apparatus at laboratory scale in which a synthetic flue gas, formed by Hg(0) vapors in a nitrogen gas stream, at a given temperature and mercury concentration, was flowed through a fixed bed of adsorbent material. Breakthrough curves and adsorption isotherms were obtained for bed temperatures of 90, 120 and 150 degrees C and for Hg(0) concentrations in the gas varying in the range of 0.8-5.0 mg/m3. The experimental gas-solid equilibrium data were used to evaluate the Langmuir parameters and the heat of adsorption. The experimental results showed that silver impregnated carbon was very effective to capture elemental mercury and the amount of mercury adsorbed by the carbon decreased as the bed temperature increased. In addition, to evaluate the possibility of adsorbent recovery, desorption was also studied. Desorption runs showed that both the adsorbing material and the mercury could be easily recovered, since at the end of desorption the residue on solid was almost negligible. The material balance on mercury and the constitutive equations of the adsorption phenomenon were integrated, leading to the evaluation of only one kinetic parameter which fits well both the experimentally determined breakthrough and desorption curves.

  17. Removal of trace level aqueous mercury by adsorption and photocatalysis on silica-titania composites.

    PubMed

    Byrne, Heather E; Mazyck, David W

    2009-10-30

    Silica-titania composites (STCs) were applied to trace level mercury solutions (100 microg/L Hg) to determine the degree of mercury removal that could be accomplished via adsorption and photocatalysis. STCs are a porous, high surface area silica substrate (> 200 m(2)/g), manufactured using sol-gel methodology, impregnated with TiO2 nanoparticles. The performance of this material along with its precursors, silica and Degussa P25 TiO2 were compared. Under adsorption alone (no UV illumination), STCs were able to achieve approximately 90% removal of mercury, which is comparable to that of Degussa P25. Silica without TiO2 performed poorly in comparison and was minimally affected by UV illumination. Contrary to expectations, the performance of Degussa P25 was not largely changed by UV irradiation and the STC was detrimentally affected under the same conditions. It was concluded that elemental mercury was formed under UV irradiation with or without the presence of TiO2 due to photochemical reactions, decreasing the mercury removal by STC. Additionally, the primary particle size of the STC was reduced to increase mass transfer. The result was improved Hg removal under adsorption and photocatalysis conditions. Improved adsorption kinetics were also achieved by altering the STC pore size and TiO2 loading.

  18. Toxicity and accumulation of mercury in three species of crabs with different osmoregulatory capacities

    SciTech Connect

    Bianchini, A.; Gilles, R.

    1996-07-01

    Synergism between mercury and salinity has been shown in invertebrates. Two authors have tied to correlate salinity effects with a higher or lower accumulation of mercury. Zauke, demonstrated lower mercury levels in several benthic invertebrates from limnic regions of the Elbe estuary when compared to those from Marine regions. On the other hand, Kendall did not report any significant difference in mercury concentrations in benthic macroinvertebrates throughout a salinity gradient in two estuaries from Georgia. In species hyperosmoregulating in diluted media, it could, however, be considered that the high water turnover would favor mercury accumulation. In this context, one could also expect a relationship between environmental salinity and mercury toxicity in different euryhaline species depending on their osmoregulatory capacities. We have tested this hypothesis analyzing the toxic effects and accumulation of mercury in three euryhaline crabs presenting different osmoregulatory capacities: Eriocheir sinensis (strong hyperosmoregulator), Carcinus maenas (weak hyperosmoregulator) and Cancer pagurus (osmoconformer). 16 refs., 4 figs., 1 tab.

  19. Multiscale characterization of pore size distributions using mercury porosimetry and nitrogen adsorption

    NASA Astrophysics Data System (ADS)

    Paz-Ferreiro, J.; Tarquis, A. M.; Miranda, J. G. V.; Vidal Vázquez, E.

    2009-04-01

    The soil pore space is a continuum extremely variable in size, including structures smaller than nanometres and as large as macropores or cracks with millimetres or even centimetres size. Pore size distributions (PSDs) affects important soil functions, such as those related with transmission and storage of water, and root growth. Direct and indirect measurements of PSDs are becoming increasingly used to characterize soil structure. Mercury injection porosimetry and nitrogen adsorption isotherms are techniques commonly employed for assessing equivalent pore size diameters in the range from about 50 nm to 100 m and 2 to 500 nm, respectively. The multifractal formalism was used to describe Hg injection curves and N2 adsorption isotherms from two series of a Mollisol cultivated under no tillage and minimum tillage. Soil samples were taken from 0-10, 10-20 and 20-30 cm depths in two experimental fields located in the north of Buenos Aires and South of Santa Fe provinces, Argentina. All the data sets analyzed from the two studied soil attributes showed remarkably good scaling trends as assessed by singularity spectrum and generalized dimension spectrum. Both, experimental Hg injection curves and N2 adsorption isotherms could be fitted reasonably well with multifractal models. A wide variety of singularity and generalized dimension spectra was found for the variables. The capacity dimensions, D0, for both Hg injection and N2 adsorption data were not significantly different from the Euclidean dimension. However, the entropy dimension, D1, and correlation dimension, D2, obtained from mercury injection and nitrogen adsorption data showed significant differences. So, D1 values were on average 0.868 and varied from 0.787 to 0.925 for Hg intrusion curves. Entropy dimension, D1, values for N2 adsorption isotherms were on average 0.582 significantly lower than those obtained when using the former technique. Twenty-three out of twenty-four N2 isotherms had D1 values in a

  20. Adsorption of pyrantel pamoate on mercury from aqueous solutions: studies by stripping voltammetry.

    PubMed

    Gupta, Vinod K; Jain, Rajeev; Jadon, N; Radhapyari, K

    2010-10-01

    Adsorption and electrochemical reduction of pyrantel pamoate are studied in Britton Robinson buffer medium at hanging mercury drop electrode (HMDE) by Adsorptive Stripping Voltammetric technique. The peak current shows a linear dependence with the drug concentration over the range 250 ng mL(-1) to 64 microg mL(-1). Applicability to assay the drug in urine samples is illustrated in the concentration range 5-20 microg mL(-1).

  1. EFFECT OF MOISTURE ON ADSORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBON

    EPA Science Inventory

    The paper discusses experiments using activated carbon to capture elemental mercury (Hgo), and a bench-scale dixed-bed reactor and a flow reactor to determine the role of surface moisture in Hgo adsorption. Three activated-carbon samples, with different pore structure and ash co...

  2. ROLE OF HCL IN ADSORPTION OF ELEMENTAL MERCURY VAPOR BY CALCIUM-BASED SORBENTS

    EPA Science Inventory

    The paper gives results of a study to identify active sites and surface functional groups that may contribute to the adsorption of elemental mercury (Hg?) by relatively inexpensive calcium (Ca)-based sorbents. (NOTE: Hg? capture has been mostly investigated using high-surface-ar...

  3. IMPORTANCE OF ACTIVATED CARBON'S OXYGEN SURFACE FUNCTIONAL GROUPS ON ELEMENTAL MERCURY ADSORPTION

    EPA Science Inventory

    The effect of varying physical and chemical properties of activated carbons on adsorption of elemental mercury [Hg(0)] was studied by treating two activated carbons to modify their surface functional groups and pore structures. Heat treatment (1200 K) in nitrogen (N2), air oxidat...

  4. IMPORTANCE OF ACTIVATED CARBON'S OXYGEN SURFACE FUNCTIONAL GROUPS ON ELEMENTAL MERCURY ADSORPTION

    EPA Science Inventory

    The effect of varying physical and chemical properties of activated carbons on adsorption of elemental mercury [Hg(0)] was studied by treating two activated carbons to modify their surface functional groups and pore structures. Heat treatment (1200 K) in nitrogen (N2), air oxidat...

  5. EFFECT OF MOISTURE ON ADSORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBON

    EPA Science Inventory

    The paper discusses experiments using activated carbon to capture elemental mercury (Hgo), and a bench-scale dixed-bed reactor and a flow reactor to determine the role of surface moisture in Hgo adsorption. Three activated-carbon samples, with different pore structure and ash co...

  6. ROLE OF HCL IN ADSORPTION OF ELEMENTAL MERCURY VAPOR BY CALCIUM-BASED SORBENTS

    EPA Science Inventory

    The paper gives results of a study to identify active sites and surface functional groups that may contribute to the adsorption of elemental mercury (Hg?) by relatively inexpensive calcium (Ca)-based sorbents. (NOTE: Hg? capture has been mostly investigated using high-surface-ar...

  7. THE EFFECT OF ACTIVATED CARBON SURFACE MOISTURE ON LOW TEMPERATURE MERCURY ADSORPTION

    EPA Science Inventory

    Experiments with elemental mercury (Hg0) adsorption by activated carbons were performed using a bench-scale fixed-bed reactor at room temperature (27 degrees C) to determine the role of surface moisture in capturing Hg0. A bituminous-coal-based activated carbon (BPL) and an activ...

  8. THE EFFECT OF ACTIVATED CARBON SURFACE MOISTURE ON LOW TEMPERATURE MERCURY ADSORPTION

    EPA Science Inventory

    Experiments with elemental mercury (Hg0) adsorption by activated carbons were performed using a bench-scale fixed-bed reactor at room temperature (27 degrees C) to determine the role of surface moisture in capturing Hg0. A bituminous-coal-based activated carbon (BPL) and an activ...

  9. Effect of calcium on adsorption capacity of powdered activated carbon.

    PubMed

    Li, Gang; Shang, Junteng; Wang, Ying; Li, Yansheng; Gao, Hong

    2013-12-01

    We investigated the effect of calcium ion on the adsorption of humic acid (HA) (as a target pollutant) by powered activated carbon. The HA adsorption isotherms at different pH and kinetics of two different solutions including HA alone and HA doped Ca(2+), were performed. It was showed that the adsorption capacity of powdered activated carbon (PAC) for HA was markedly enhanced when Ca(2+) was doped into HA. Also, HA and Ca(2+) taken as nitrate were tested on the uptake of each other respectively and it was showed that the adsorbed amounts of both of them were significantly promoted when HA and calcium co-existed. Furthermore, the adsorbed amount of HA slightly decreased with the increasing of Ca(2+) concentration, whereas the amount of calcium increased with the increasing of HA concentration, but all above the amounts without addition. Finally, the change of pH before and after adsorption process is studied. In the two different solutions including HA alone and HA doped Ca(2+), pH had a small rise, but the extent of pH of later solution was bigger.

  10. Proteomic analysis of protein adsorption capacity of different haemodialysis membranes.

    PubMed

    Urbani, Andrea; Lupisella, Santina; Sirolli, Vittorio; Bucci, Sonia; Amoroso, Luigi; Pavone, Barbara; Pieroni, Luisa; Sacchetta, Paolo; Bonomini, Mario

    2012-04-01

    Protein-adsorptive properties are a key feature of membranes used for haemodialysis treatment. Protein adsorption is vital to the biocompatibility of a membrane material and influences membrane's performance. The object of the present study is to investigate membrane biocompatibility by correlating the adsorbed proteome repertoire with chemical feature of the membrane surfaces. Dialyzers composed of either cellulose triacetate (Sureflux 50 L, effective surface area 0.5 m(2); Nipro Corporation, Japan) or the polysulfone-based helixone (FX40, effective surface area 0.4 m(2); Fresenius Medical Care AG, Germany) materials were employed to develop an ex vivo apparatus to study protein adsorption. Adsorbed proteins were eluted by a strong chaotropic buffer condition and investigated by a proteomic approach. The profiling strategy was based on 2D-electrophoresis separation of desorbed protein coupled to MALDI-TOF/TOF analysis. The total protein adsorption was not significantly different between the two materials. An average of 179 protein spots was visualised for helixone membranes while a map of retained proteins of cellulose triacetate membranes was made up of 239 protein spots. The cellulose triacetate material showed a higher binding capacity for albumin and apolipoprotein. In fact, a number of different protein spots belonging to the gene transcript of albumin were visible in the cellulose triacetate map. In contrast, helixone bound only a small proportion of albumin, while proved to be particularly active in retaining protein associated with the coagulation cascade, such as the fibrinogen isoforms. Our data indicate that proteomic techniques are a useful approach for the investigation of proteins surface-adsorbed onto haemodialysis membranes, and may provide a molecular base for the interpretation of the efficacy and safety of anticoagulation treatment during renal replacement therapy.

  11. Chemical modification of oxalate decarboxylase to improve adsorption capacity.

    PubMed

    Lin, Rihui; He, Junbin; Wu, Jia; Cai, Xinghua; Long, Han; Chen, Shengfeng; Liu, Haiqian

    2017-05-01

    In order to enhance the adsorption capacity of oxalate decarboxylase (Oxdc) on calcium oxalate monohydrate crystals and improve the application performance of Oxdc, chemical modification of Oxdc with ethylenediaminetetraacetic dianhydride (EDTAD) was investigated in this work. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and liquid chromatography tandem mass spectrometry (LC/MS) analysis results demonstrated that Oxdc and EDTAD have been covalently bound, and suggested that the chemical modification occurred at the free amino of the side chain and the α-amine of the N-terminus of Oxdc. Fluorescene and circular dichroic measurement showed that the structure and conformation of Oxdc were tinily altered after modification by EDTAD. The optimum pH of EDTAD-modified Oxdc was shifted to the alkaline side about 1.5 unit and it has a higher thermostability. The analysis of kinetic parameters indicated that the EDTAD-modified Oxdc showed a higher affinity towards the substrate. Through modification the adsorption capacity of Oxdc onto CaOx monohydrate crystals was increased by 42.42%. Copyright © 2017. Published by Elsevier B.V.

  12. Designing of the Nanosized Centers for Adsorption of Mercury (II) on a Silica Surface

    NASA Astrophysics Data System (ADS)

    Belyakova, L. A.; Lyashenko, D. Yu.; Shvets, O. M.

    The chemical design of nanosized centers for mercury (II)adsorption on a silica surface has been carried out. Chemically bonded molecules of β-cyclodextrin are the centers of adsorption. The kinetics of Hg (II) adsorption is analyzed within the framework of Lagergren model for processes of pseudo-first and pseudo-second orders. It was shown that the adsorption isotherm for β-cyclodextrin-containing silica is well described by Langmuir equation. The formation of inclusion complexes "β-cyclodextrin-nitrate-ion" with ratio 1:1 and supramolecules with composition C42H70O34·4Hg(NO3)2 on a surface of β-cyclodextrin-containing silica has been proved using IR and 1H NMR spectroscopy, spectrophotometry, elemental analysis, X-ray diffraction, and chemical analysis of surface compounds.

  13. Designing of the Nanosized Centers for Adsorption of Mercury (II) on a Silica Surface

    NASA Astrophysics Data System (ADS)

    Belyakova, L. A.; Lyashenko, D. Yu.; Shvets, O. M.

    The chemical design of nanosized centers for mercury (II)adsorption on a silica surface has been carried out. Chemically bonded molecules of β-cyclodextrin are the centers of adsorption. The kinetics of Hg (II) adsorption is analyzed within the framework of Lagergren model for processes of pseudo-first and pseudo-second orders. It was shown that the adsorption isotherm for β-cyclodextrin-containing silica is well described by Langmuir equation. The formation of inclusion complexes “β-cyclodextrin-nitrate-ion” with ratio 1:1 and supramolecules with composition C42H70O34·4Hg(NO3)2 on a surface of β-cyclodextrin-containing silica has been proved using IR and 1H NMR spectroscopy, spectrophotometry, elemental analysis, X-ray diffraction, and chemical analysis of surface compounds.

  14. Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed and Entrained-Flow Reactor

    SciTech Connect

    Buitrago, Paula A.; Morrill, Mike; Lighty, JoAnn S.; Silcox, Geoffrey D.

    2009-06-01

    This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO2, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO2, and NO2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

  15. Enhanced adsorption of mercury ions on thiol derivatized single wall carbon nanotubes.

    PubMed

    Bandaru, Narasimha Murthy; Reta, Nekane; Dalal, Habibullah; Ellis, Amanda V; Shapter, Joseph; Voelcker, Nicolas H

    2013-10-15

    Thiol-derivatized single walled carbon nanotube (SWCNT-SH) powders were synthesized by reacting acid-cut SWCNTs with cysteamine hydrochloride using carbodiimide coupling. Infrared (IR) spectroscopy, Raman spectroscopy and thermogravimetric analysis confirmed the successful functionalization of the SWCNTs. SWCNT-SH powders exhibited a threefold higher adsorption capacity for Hg(II) ions compared to pristine SWCNTs, and a fourfold higher adsorption capacity compared to activated carbon. The influence of adsorption time, pH, initial metal concentration and adsorbent dose on Hg(II) ion removal was investigated. The maximum adsorption capacity of the SWCNT-SH powders was estimated by using equilibrium isotherms, such as Freundlich and Langmuir, and the maximum adsorption capacity of the SWCNT-SH powder was found to be 131 mg/g. A first-order rate model was employed to describe the kinetic adsorption process of Hg(II) ions onto the SWCNT-SH powders. Desorption studies revealed that Hg(II) ions could be easily removed from the SWCNT-SH powders by altering the pH. Further, the adsorption efficiency of recovered SWCNT-SH powders was retained up to 91%, even after 5 adsorption/desorption cycles.

  16. Adsorption and Catalytic Oxidation of Gaseous Elemental Mercury in Flue Gas over MnOx/Alumina

    SciTech Connect

    Qiao, S.H.; Chen, J.; Li, J.F.; Qu, Z.; Liu, P.; Yan, N.Q.; Jia, J.Q.

    2009-04-15

    MnOx/Al{sub 2}O{sub 3} catalysts (i.e., impregnating manganese oxide on alumina) were employed to remove elemental mercury (Hg{sup 0}) from flue gas. MnOx/Al{sub 2}O{sub 3} was found to have significant adsorption performance on capturing Hg{sup 0} in the absence of hydrogen chloride (HCl), and its favorable adsorption temperature was about 600 K. However, the catalytic oxidation of Hg{sup 0} became dominant when HCl or chlorine (Cl{sub 2}) was present in flue gas, and the removal efficiency of Hg{sup 0} was up to 90% with 20 ppm of HCl or 2 ppm of Cl{sub 2}. In addition, the catalysts with adsorbed mercury could be chemically regenerated by rinsing with HCl gas to strip off the adsorbed mercury in the form of HgCl{sub 2}. Sulfur dioxide displayed inhibition to the adsorption of Hg{sup 0} on the catalysts, but the inhibition was less to the catalytic oxidation of Hg{sup 0}, especially in the presence of Cl{sub 2}. The analysis results of XPS and pyrolysis-AAS indicated that the adsorbed mercury was mainly in the forms of mercuric oxide (Hg{sup 0}) and the weakly bonded speciation, and the ratio of them varied with the adsorption amount and manganese content on catalysts. The multifunctional performances of MnOx/Al{sub 2}O{sub 3} on the removal of Hg{sup 0} appeared to the promising in the industrial applications.

  17. Polanyi Evaluation of Adsorptive Capacities of Commercial Activated Carbons

    NASA Technical Reports Server (NTRS)

    Monje, Oscar; Surma, Jan M.

    2017-01-01

    Commercial activated carbons from Calgon (207C and OVC) and Cabot Norit (RB2 and GCA 48) were evaluated for use in spacecraft trace contaminant control filters. The Polanyi potential plots of the activated carbons were compared using to those of Barnebey-Cheney Type BD, an untreated activated carbon with similar properties as the acid-treated Barnebey-Sutcliffe Type 3032 utilized in the TCCS. Their adsorptive capacities under dry conditions were measured in a closed loop system and the sorbents were ranked for their ability to remove common VOCs found in spacecraft cabin air. This comparison suggests that these sorbents can be ranked as GCA 48 207C, OVC RB2 for the compounds evaluated.

  18. Adsorption of multi-heavy metals Zn and Cu onto surficial sediments: modeling and adsorption capacity analysis.

    PubMed

    Li, Shanshan; Zhang, Chen; Wang, Meng; Li, Yu

    2014-01-01

    Improved multiple regression adsorption models (IMRAMs) was developed to estimate the adsorption capacity of the components [Fe oxides (Fe), Mn oxides (Mn), organic materials (OMs), residuals] in surficial sediments for multi-heavy metal Zn and Cu. IMRAM is an improved version over MRAM, which introduces a computer program in the model developing process. As MRAM, Zn(Cu) IMRAM, and Cu(Zn) IMRAM again confirmed that there is significant interaction effects that control the adsorption of compounded Zn and Cu, which was neglected by additional adsorption model. The verification experiment shows that the relative deviation of the IMRAMs is less than 13%. It is revealed by the IMRAMs that Mn, which has the greatest adsorption capability for compounded Zn and Cu (54.889 and 161.180 mg/l, respectively), follows by interference adsorption capacity of Fe/Mn (-1.072 and -24.591 mg/l respectively). Zn and Cu influence each other through different mechanisms. When Zn is the adsorbate, compounded Cu mainly affects the adsorption capacities of Fe/Mn and Fe/Mn/OMs; while when Cu is the adsorbate, compounded Zn mainly exerts its effect on Mn, Fe/Mn, and Mn/OMs. It also shows that the compounded Zn or Cu weakened the interference adsorption of Fe/Mn, and meanwhile, strengthened the interference adsorption of Mn/OMs.

  19. Influence of the surface structure of β-cyclodexrin-containing silica on the adsorption of mercury nitrate from dilute solutions

    NASA Astrophysics Data System (ADS)

    Belyakova, L. A.; Lyashenko, D. Yu.; Shvets, A. N.

    2010-04-01

    The construction of adsorption sites for mercury(II) by chemical immobilization of β-cyclodextrin and its functional derivatives on a surface of macroporous amorphous silica is proposed. It is shown that the adsorption of mercury(II) is adequately described by the Langmuir isotherm equation for monolayer adsorption on localized sites of energetically homogeneous surfaces. It is established that the considerably increased sorption of mercury nitrate on silica modified by different β-cyclodextrins is due to the formation of 1: 1 β-cyclodextrin-nitrate ion inclusion complexes on the surface and the participation of side functional groups of the upper edge of immobilized β-cyclodextrin molecules in the formation of mixed-ligand mercury(II) complexes.

  20. Adsorption of mercury on lignin: combined surface complexation modeling and X-ray absorption spectroscopy studies.

    PubMed

    Lv, Jitao; Luo, Lei; Zhang, Jing; Christie, Peter; Zhang, Shuzhen

    2012-03-01

    Adsorption of mercury (Hg) on lignin was studied at a range of pH values using a combination of batch adsorption experiments, a surface complexation model (SCM) and synchrotron X-ray absorption spectroscopy (XAS). Surface complexation modeling indicates that three types of acid sites on lignin surfaces, namely aliphatic carboxylic-, aromatic carboxylic- and phenolic-type surface groups, contributed to Hg(II) adsorption. The bond distance and coordination number of Hg(II) adsorption samples at pH 3.0, 4.0 and 5.5 were obtained from extended X-ray absorption fine structure (EXAFS) spectroscopy analysis. The results of SCM and XAS combined reveal that the predominant adsorption species of Hg(II) on lignin changes from HgCl(2)(0) to monodentate complex -C-O-HgCl and then bidentate complex -C-O-Hg-O-C- with increasing pH value from 2.0 to 6.0. The good agreement between SCM and XAS results provides new insight into understanding the mechanisms of Hg(II) adsorption on lignin.

  1. Adsorption capacity study of carbon nanopowder produced by laser pyrolisis

    NASA Astrophysics Data System (ADS)

    Sonu, Marcel; Savu, Ion; Pastean, Laurentiu; Voicu, Ion N.; Soare, Iuliana; Morjan, Ion G.; Grigoriu, Constantin

    2004-10-01

    The paper presents the experimental results on adsorption properties of carbon nanopowders which have been obtained by laser pyrolysis of hydrocarbon-based mixtures. We have investigated the adsorption of benzene, n-hexane and ciclohexane. The influence of the nanocarbon morphology (which depends on gaseous precursors and synthesis conditions) on adsorption characteristics is reported.

  2. Assessment of pumped mercury vapour adsorption tubes as passive samplers using a micro-exposure chamber.

    PubMed

    Brown, Richard J C; Burdon, Melia K; Brown, Andrew S; Kim, Ki-Hyun

    2012-09-01

    Mercury vapour adsorption tubes manufactured for pumped sampling and analysis have been evaluated for their performance as passive samplers. This has been done by exposing these tubes in a novel micro-exposure chamber. The uptake rates of these tubes have been found to be low (approximately 0.215 ml min(-1)) as compared to bespoke passive samplers for mercury vapour (typically in excess of 50 ml min(-1)). The measured uptake rates were shown to vary significantly between tubes and this was attributed to the variability in the air-sorbent interface and the proportion of the cross sectional area removed by the crimp in the quartz tubes used to secure the sorbent material. As a result of this variability the uptake rate of each tube must be determined using the micro-exposure chamber prior to deployment. Results have shown that the uptake rate determined in the micro-exposure chamber is invariant of concentration, and therefore these uptakes rates may be determined at a high mercury vapour concentration for many tubes at once in less than one hour. The uptake rate of the adsorption tubes under these conditions may be determined with a precision of 5%. Measurements made on a limited field trial in indoor and outdoor ambient air have shown that these tubes give results in acceptable agreement with more traditional pumped sampling methods, although longer sampling periods are required in order to reduce the uncertainty of the measurement, which is currently approximately 30%.

  3. Removal of mercury(II) ions in aqueous solution using the peel biomass of Pachira aquatica Aubl: kinetics and adsorption equilibrium studies.

    PubMed

    Santana, Andrea J; dos Santos, Walter N L; Silva, Laiana O B; das Virgens, Cesário F

    2016-05-01

    Mercury is a highly toxic substance that is a health hazard to humans. This study aims to investigate powders obtained from the peel of the fruit of Pachira aquatica Aubl, in its in natura and/or acidified form, as an adsorbent for the removal of mercury ions in aqueous solution. The materials were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. The infrared spectra showed bands corresponding to the axial deformation of carbonyls from carboxylic acids, the most important functional group responsible for fixing the metal species to the adsorbent material. The thermograms displayed mass losses related to the decomposition of three major components, i.e., hemicellulose, cellulose, and lignin. The adsorption process was evaluated using cold-vapor atomic fluorescence spectrometry (CV AFS) and cold-vapor atomic absorption spectrometry (CV AAS). Three isotherm models were employed. The adsorption isotherm model, Langmuir-Freundlich, best represented the adsorption process, and the maximum adsorption capacity was predicted to be 0.71 and 0.58 mg g(-1) at 25 °C in nature and acidified, respectively. Adsorption efficiencies were further tested on real aqueous wastewater samples, and removal of Hg(II) was recorded as 69.6 % for biomass acidified and 76.3 % for biomass in nature. Results obtained from sorption experiments on real aqueous wastewater samples revealed that recovery of the target metal ions was very satisfactory. The pseudo-second-order model showed the best correlation to the experimental data. The current findings showed that the investigated materials are potential adsorbents for mercury(II) ion removal in aqueous solution, with acidified P. aquatica Aubl being the most efficient adsorbent.

  4. Advantages of using a mercury coated, micro-wire, electrode in adsorptive cathodic stripping voltammetry.

    PubMed

    Gun, Jenny; Salaün, Pascal; van den Berg, Constant M G

    2006-06-30

    A mercury coated, gold, micro-wire electrode is used here for the determination of iron in seawater by catalytic cathodic stripping voltammetry (CSV) with a limit of detection of 0.1 nM Fe at a 60s adsorption time. It was found that the electrode surface is stable for extended periods of analyses (at least five days) and that it is reactivated by briefly (2s) applying a negative potential prior to each scan. Advantages of this electrode over mercury drop electrodes are that metallic mercury use is eliminated and that it can be readily used for flow analysis. This is demonstrated here by the determination of iron in seawater by continuous flow analysis. It is likely that this method can be extended to other elements. Experiments using bismuth coated, carbon fibre, electrodes showed that the bismuth catalyses the oxidation of the important oxidants bromate and hydrogen peroxide, which makes it impossible to use bismuth based electrodes for catalytic CSV involving these oxidants. For this reason mercury coated electrodes retain a major advantage for catalytic voltammetric analyses.

  5. Enhanced chromium adsorption capacity via plasma modification of natural zeolites

    NASA Astrophysics Data System (ADS)

    Cagomoc, Charisse Marie D.; Vasquez, Magdaleno R., Jr.

    2017-01-01

    Natural zeolites such as mordenite are excellent adsorbents for heavy metals. To enhance the adsorption capacity of zeolite, sodium-exchanged samples were irradiated with 13.56 MHz capacitively coupled radio frequency (RF) argon gas discharge. Hexavalent chromium [Cr(VI)] was used as the test heavy metal. Pristine and plasma-treated zeolite samples were soaked in 50 mg/L Cr solution and the amount of adsorbed Cr(VI) on the zeolites was calculated at predetermined time intervals. Compared with untreated zeolite samples, initial Cr(VI) uptake was 70% higher for plasma-treated zeolite granules (50 W 30 min) after 1 h of soaking. After 24 h, all plasma-treated zeolites showed increased Cr(VI) uptake. For a 2- to 4-month period, Cr(VI) uptake increased about 130% compared with untreated zeolite granules. X-ray diffraction analyses between untreated and treated zeolite samples revealed no major difference in terms of its crystal structure. However, for plasma-treated samples, an increase in the number of surface defects was observed from scanning electron microscopy images. This increase in the number of surface defects induced by plasma exposure played a crucial role in increasing the number of active sorption sites on the zeolite surface.

  6. High-capacity adsorption of aniline using surface modification of lignocellulose-biomass jute fibers.

    PubMed

    Gao, Da-Wen; Hu, Qi; Pan, Hongyu; Jiang, Jiping; Wang, Peng

    2015-10-01

    Pyromellitic dianhydride (PMDA) modified jute fiber (MJF) were prepared with microwave treatment to generate a biosorbent for aniline removal. The characterization of the biosorbent was investigated by SEM, BET and FT-IR analysis to discuss the adsorption mechanism. The studies of various factors influencing the adsorption behavior indicated that the optimum dosage for aniline adsorption was 3g/L, the maximum adsorption capacity was observed at pH 7.0 and the adsorption process is spontaneous and endothermic. The aniline adsorption follows the pseudo second order kinetic model and Langmuir isotherm model. Moreover, the biosorbent could be regenerated through the desorption of aniline by using 0.5M HCl solution, and the adsorption capacity after regeneration is even higher than that of virgin MJF. All these results prove MJF is a promising adsorbent for aniline removal in wastewater.

  7. Capability of defective graphene-supported Pd13 and Ag13 particles for mercury adsorption

    NASA Astrophysics Data System (ADS)

    Meeprasert, Jittima; Junkaew, Anchalee; Rungnim, Chompoonut; Kunaseth, Manaschai; Kungwan, Nawee; Promarak, Vinich; Namuangruk, Supawadee

    2016-02-01

    Reactivity of single-vacancy defective graphene (DG) and DG-supported Pdn and Agn (n = 1, 13) for mercury (Hg0) adsorption has been studied using density functional theory calculation. The results show that Pdn binds defective site of DG much stronger than the Agn, while metal nanocluster binds DG stronger than single metal atom. Metal clustering affects the adsorption ability of Pd composite while that of Ag is comparatively less. The binding strength of -8.49 eV was found for Pd13 binding on DG surface, indicating its high stability. Analyses of structure, energy, partial density of states, and d-band center (ɛd) revealed that the adsorbed metal atom or cluster enhances the reactivity of DG toward Hg adsorption. In addition, the Hg adsorption ability of Mn-DG composite is found to be related to the ɛd of the deposited Mn, in which the closer ɛd of Mn to the Fermi level correspond to the higher adsorption strength of Hg on Mn-DG composite. The order of Hg adsorption strength on Mn-DG composite are as follows: Pd13 (-1.68 eV) >> Ag13 (-0.67 eV) ∼ Ag1 (-0.69 eV) > Pd1 (-0.62 eV). Pd13-DG composite is therefore more efficient sorbent for Hg0 removal in terms of high stability and high adsorption reactivity compared to the Ag13. Further design of highly efficient carbon based sorbents should be focused on tailoring the ɛd of deposited metals.

  8. Adsorption-desorption characteristics of mercury in paddy soils of China.

    PubMed

    Jing, Y D; He, Z L; Yang, X E

    2008-01-01

    Mercury (Hg) has received considerable attention because of its association with various human health problems. Adsorption-desorption behavior of Hg at contaminated levels in two paddy soils was investigated. The two representative soils for rice production in China, locally referred to as a yellowish red soil (YRS) and silty loam soil (SLS) and classified as Gleyi-Stagnic Anthrosols in FAO/UNESCO nomenclature, were respectively collected from Jiaxin County and Xiasha District of Hangzhou City, Zhejiang Province. The YRS adsorbed more Hg(2+) than the SLS. The characteristics of Hg adsorption could be described by the simple Langmuir adsorption equation (r2 = 0.999 and 0.999, P < 0.01, respectively, for the SLS and YRS). The maximum adsorption values (Xm) that were obtained from the simple Langmuir model were 111 and 213 mg Hg(2+) kg(-1) soil, respectively, for the SLS and YRS. Adsorption of Hg(2+) decreased soil pH by 0.75 unit for the SLS soil and 0.91 unit for the YRS soil at the highest loading. The distribution coefficient (kd) of Hg in the soil decreased exponentially with increasing Hg(2+) loading. After five successive desorptions with 0.01 mol L(-1) KCl solution (pH 5.4), 0 to 24.4% of the total adsorbed Hg(2+) in the SLS soil was desorbed and the corresponding value of the YRS soil was 0 to 14.4%, indicating that the SLS soil had a lower affinity for Hg(2+) than the YRS soil at the same Hg(2+) loading. Different mechanisms are likely involved in Hg(2+) adsorption-desorption at different levels of Hg(2+) loading and between the two soils.

  9. [Effects of particle-sizes, pH and organic matter on adsorption and desorption of mercury to sediments in the Songhua River].

    PubMed

    Zhu, Hui; Yan, Bai-Xing; Zhang, Feng-Song; Lu, Yong-Zheng; Wang, Li-Xia

    2010-10-01

    The present study aims to further reveal the environmental behavior of mercury on sediments surface. Effects of particle-sizes, pH and concentrations of dissolved organic matter (DOM) on mercury adsorption and desorption to the surface of sediments in the Songhua River were investigated by simulation experiments. A distinct variety of absorption ability among sediments with different particle-sizes was observed. Under this experimental condition, the absorption ability increased inversely with particle-size of sediments. In all absorption systems, mercury adsorption was enhanced when pH increased from 3.5 to 4.5, while mercury adsorption was inhibited significantly with the increasing of pH when pH values were above 4.5. With the increasing of pH values, the desorption of mercury presented a decreasing-increasing trend, the minimum desorption occurred at pH 5. Citric acid inhibited the mercury adsorption, and the intensity was correlated with mercury concentrations. Effects of citric acid on desorption of mercury were also apparently. With the increasing of citric acid concentrations, its effect on desorption presented a trend as enhanced-inhibited-steadied. Therefore, the above factors affected the mercury adsorption and desorption obviously, and it was necessary to take these factors into consideration in conducting the rivers' mercury control and dealing with a sudden pollution incident.

  10. Saline cathartics and adsorptive capacity of activated charcoal for doxycycline.

    PubMed

    Afonne, O J; Orisakwe, O E; Ofuefule, S I; Tsalha, S; Obi, E; Ilondu, N A; Okorie, O

    2002-01-01

    The effects of sodium chloride and sodium citrate on the in vitro adsorption of doxycycline to activated charcoal have been studied. Solutions of doxycycline alone and doxycycline with 7.5 mg/ml cathartic solutions were vortex-mixed for 30 s with different quantities of activated charcoal, incubated for 30 min at 37 degrees C and analyzed for free doxycycline spectrophotometrically at 348 nm. Addition of NaCl had a significant (p<0.05) increase while sodium citrate produced a significant (p<0.05) decrease in the adsorption of doxycycline on activated charcoal. In all, the adsorption doxycycline on activated charcoal obeyed quantity-dependent kinetics.

  11. Modeling high adsorption capacity and kinetics of organic macromolecules on super-powdered activated carbon.

    PubMed

    Matsui, Yoshihiko; Ando, Naoya; Yoshida, Tomoaki; Kurotobi, Ryuji; Matsushita, Taku; Ohno, Koichi

    2011-02-01

    The capacity to adsorb natural organic matter (NOM) and polystyrene sulfonates (PSSs) on small particle-size activated carbon (super-powdered activated carbon, SPAC) is higher than that on larger particle-size activated carbon (powdered-activated carbon, PAC). Increased adsorption capacity is likely attributable to the larger external surface area because the NOM and PSS molecules do not completely penetrate the adsorbent particle; they preferentially adsorb near the outer surface of the particle. In this study, we propose a new isotherm equation, the Shell Adsorption Model (SAM), to explain the higher adsorption capacity on smaller adsorbent particles and to describe quantitatively adsorption isotherms of activated carbons of different particle sizes: PAC and SPAC. The SAM was verified with the experimental data of PSS adsorption kinetics as well as equilibrium. SAM successfully characterized PSS adsorption isotherm data for SPACs and PAC simultaneously with the same model parameters. When SAM was incorporated into an adsorption kinetic model, kinetic decay curves for PSSs adsorbing onto activated carbons of different particle sizes could be simultaneously described with a single kinetics parameter value. On the other hand, when SAM was not incorporated into such an adsorption kinetic model and instead isotherms were described by the Freundlich model, the kinetic decay curves were not well described. The success of the SAM further supports the adsorption mechanism of PSSs preferentially adsorbing near the outer surface of activated carbon particles.

  12. High-capacity hydrogen and nitric oxide adsorption and storage in a metal-organic framework.

    PubMed

    Xiao, Bo; Wheatley, Paul S; Zhao, Xuebo; Fletcher, Ashleigh J; Fox, Sarah; Rossi, Adriano G; Megson, Ian L; Bordiga, S; Regli, L; Thomas, K Mark; Morris, Russell E

    2007-02-07

    Gas adsorption experiments have been carried out on a copper benzene tricarboxylate metal-organic framework material, HKUST-1. Hydrogen adsorption at 1 and 10 bar (both 77 K) gives an adsorption capacity of 11.16 mmol H2 per g of HKUST-1 (22.7 mg g(-)1, 2.27 wt %) at 1 bar and 18 mmol per g (36.28 mg g(-)1, 3.6 wt %) at 10 bar. Adsorption of D2 at 1 bar (77 K) is between 1.09 (at 1 bar) and 1.20(at <100 mbar) times the H2 values depending on the pressure, agreeing with the theoretical expectations. Gravimetric adsorption measurements of NO on HKUST-1 at 196 K (1 bar) gives a large adsorption capacity of approximately 9 mmol g(-1), which is significantly greater than any other adsorption capacity reported on a porous solid. At 298 K the adsorption capacity at 1 bar is just over 3 mmol g(-1). Infra red experiments show that the NO binds to the empty copper metal sites in HKUST-1. Chemiluminescence and platelet aggregometry experiments indicate that the amount of NO recovered on exposure of the resulting complex to water is enough to be biologically active, completely inhibiting platelet aggregation in platelet rich plasma.

  13. Preparation of amine group-containing chelating fiber for thorough removal of mercury ions.

    PubMed

    Ma, Nianfang; Yang, Ying; Chen, Shuixia; Zhang, Qikun

    2009-11-15

    An aminated chelating fiber (AF) with high adsorption capacity for mercury ions was prepared by grafting copolymerization of acrylonitrile onto polypropylene fiber, followed by aminating with chelating molecule diethylenetriamine. Effects of reaction conditions such as temperature, reaction time, bath ratio and dosage of catalyst on the grafting yield were studied. Chemical structure, tensile strength and thermal stability of AF were characterized. The adsorption performances for mercury were evaluated by batch adsorption experiments and kinetic experiments. The results show that AF is effective for the removal of mercury over a wide range of pH. The chelating fiber also shows much higher adsorption capacities for mercury, the equilibrium adsorption amount could be as high as 657.9 mg/g for mercury. The high adsorption capacity of Hg(2+) on AF is resulted from the strong chelating interaction between amine groups and mercury ions. Two amine groups coordinate with one mercury ion could be speculated from the adsorption capacity and amine group content on AF. The kinetic adsorption results indicate that the adsorption rates of AF for mercury are very rapid. Furthermore, the residual concentration was less than 1 microg/L with feed concentration of mercury below 1mg/L, which can meet the criterion of drinking water, which indicates that the chelating fiber prepared in this study could be applied to low-level Hg contaminated drinking water purification.

  14. Methane adsorption on aggregates of fullerenes: site-selective storage capacities and adsorption energies.

    PubMed

    Kaiser, Alexander; Zöttl, Samuel; Bartl, Peter; Leidlmair, Christian; Mauracher, Andreas; Probst, Michael; Denifl, Stephan; Echt, Olof; Scheier, Paul

    2013-07-01

    Methane adsorption on positively charged aggregates of C60 is investigated by both mass spectrometry and computer simulations. Calculated adsorption energies of 118-281 meV are in the optimal range for high-density storage of natural gas. Groove sites, dimple sites, and the first complete adsorption shells are identified experimentally and confirmed by molecular dynamics simulations, using a newly developed force field for methane-methane and fullerene-methane interaction. The effects of corrugation and curvature are discussed and compared with data for adsorption on graphite, graphene, and carbon nanotubes.

  15. Methane Adsorption on Aggregates of Fullerenes: Site-Selective Storage Capacities and Adsorption Energies

    PubMed Central

    Kaiser, Alexander; Zöttl, Samuel; Bartl, Peter; Leidlmair, Christian; Mauracher, Andreas; Probst, Michael; Denifl, Stephan; Echt, Olof; Scheier, Paul

    2013-01-01

    Methane adsorption on positively charged aggregates of C60 is investigated by both mass spectrometry and computer simulations. Calculated adsorption energies of 118–281 meV are in the optimal range for high-density storage of natural gas. Groove sites, dimple sites, and the first complete adsorption shells are identified experimentally and confirmed by molecular dynamics simulations, using a newly developed force field for methane–methane and fullerene–methane interaction. The effects of corrugation and curvature are discussed and compared with data for adsorption on graphite, graphene, and carbon nanotubes. PMID:23744834

  16. Modeling the adsorption of mercury(II) on (hydr)oxides. 2: {alpha}-FeOOH (goethite) and amorphous silica

    SciTech Connect

    Bonnissel-Gissinger, P.; Alnot, M.; Ehrhardt, J.J.; Lickes, J.P.; Behra, P.

    1999-07-15

    The surface complexation model is used to describe sorption experiments of inorganic mercury(II) in the presence of an amorphous silica, Aerosil 200, or an iron (hydr)oxide, the goethite {alpha}-FeOOH (Bayferrox 910). In the simulations, one assumes the formation of a monodentate surface complex {triple_bond}S{single_bond}OHgOH and {triple_bond}S{single_bond}OHgCl, when chlorides are present in solution. Participation of the complex {triple_bond}S{single_bond}OHgCl has been especially evidenced. Comparisons with other data from the literature have been made to investigate the influence of the nature of the oxide on the mechanism of mercury(II) adsorption. X-ray photoelectron spectroscopy was used to characterize the surface of the (hydr)oxides prior to adsorption and to observe when possible the mercury surface compounds.

  17. Efficient removal and highly selective adsorption of Hg2+ by polydopamine nanospheres with total recycle capacity

    NASA Astrophysics Data System (ADS)

    Zhang, Xiulan; Jia, Xin; Zhang, Guoxiang; Hu, Jiamei; Sheng, Wenbo; Ma, Zhiyuan; Lu, Jianjiang; Liu, Zhiyong

    2014-09-01

    This study reported a new method for efficient removal of Hg2+ from contaminated water using highly selective adsorptive polydopamine (PDA) nanospheres, which were uniform and had a small diameter (150-200 nm). The adsorption isotherms, kinetics, thermodynamics were investigated. Also, the effects of ionic strength, co-existing ions on removing ability of PDA nanospheres for Hg2+ were studied. Adsorption of Hg2+ was very fast and efficient as adsorption equilibrium was completed within 4 h and the maximum adsorption capacities were 1861.72 mg/g, 2037.22 mg/g, and 2076.81 mg/g at 298 K, 313 K, and 328 K respectively, increasing with increasing of temperature. The PDA nanospheres exhibited highly selective adsorption of Hg2+ and had a total desorption capacity of 100% in hydrochloric acid solution, pH 1. The results showed that the structure of PDA nanospheres remained almost unchanged after recycling five times. Furthermore, X-ray photoelectron spectroscopy (XPS) was employed to determine the elements of PDA nanospheres before and after Hg2+ adsorption. Considering their efficient and highly Hg2+ selective adsorption, total recycle capacity, and high stability, PDA nanospheres will be feasible in a number of practical applications.

  18. Structural properties and adsorption capacity of holocellulose aerogels synthesized from an alkali hydroxide-urea solution

    NASA Astrophysics Data System (ADS)

    Kwon, Gu-Joong; Kim, Dae-Young; Hwang, Jae-Hyun; Kang, Joo-Hyon

    2014-05-01

    A tulip tree was used to synthesize a holocellulose aerogel from an aqueous alkali hydroxide-urea solution with the substitution of an organic solvent followed by freeze-drying. For comparison, the synthesized holocellulose aerogels were divided into two groups according to the source of the hydrogel, an upper suspended layer and a bottom concentrated layer of the centrifuged solution of cellulose and NaOH/urea solvents. We investigated the effects of the temperature of the pre-cooled NaOH/urea solution ( i.e., dissolution temperature) on the pore structure and the adsorption capacity of the holocellulose aerogel. A nano-fibrillar network structure of the holocellulose aerogel was observed, with little morphological difference in pore structure for different dissolution temperatures. Both micropores and mesopores were observed in the holocellulose aerogel. The specific surface area of the holocellulose aerogel was generally greater at lower dissolution temperatures. In a series of adsorption tests using methylene blue, the holocellulose aerogel showed the greatest adsorption capacity at the lowest dissolution temperature tested (-2°C). However, the dissolution temperature generally had little effect on the adsorption capacity. The holocellulose aerogel produced from the upper suspended layer of the centrifuged hydrogel solution showed a greater porosity and adsorption capacity than the one produced from the bottom concentrated layer. Overall, the aerogel made by utilizing a delignified tulip tree display a high surface area and a high adsorption property, indicating its possible application in eco-friendly adsorption materials.

  19. Solid phase extraction and spectrophotometric determination of mercury by adsorption of its diphenylthiocarbazone complex on an alumina column.

    PubMed

    Rajesh, N; Gurulakshmanan, G

    2008-02-01

    A simple method has been developed for the preconcentration of mercury based on the adsorption of its diphenylthiocarbazone complex on a neutral alumina column. The influence of acidity, eluting agents, stability of the column, sample volume and interfering ions has been investigated in detail. The adsorbed complex could be eluted using environmentally benign polyethylene glycol (PEG 400) and the concentration of mercury was determined by visible spectrophotometry at a wavelength maximum of 520nm. A detection limit of 4microgL(-1) could be achieved and the developed procedure was successfully applied for the determination of mercury in spiked water samples and city waste incineration ash (CRM176). The preconcentration factor attainable for quantitative recovery (>95%) of mercury(II) was 100 for a 1000mL sample volume.

  20. Mercury

    MedlinePlus

    Mercury is an element that is found in air, water and soil. It has several forms. Metallic mercury is a shiny, silver-white, odorless liquid. If ... with other elements to form powders or crystals. Mercury is in many products. Metallic mercury is used ...

  1. Cadmium, mercury, and nickel adsorption by tetravalent manganese feroxyhyte: selectivity, kinetic modeling, and thermodynamic study.

    PubMed

    Kokkinos, Evgenios; Soukakos, Konstantinos; Kostoglou, Margaritis; Mitrakas, Manassis

    2017-07-28

    This study is aiming to investigate tetravalent manganese feroxyhyte (TMFx) adsorption efficiency in removing heavy metals. The motivation of this study was the fact that TMFx is a highly negatively charged nanostructure material and that the metals Cd, Hg, and Ni were characterized as priority pollutants for drinking water. TMFx was evaluated through batch and continuous flow experiments in National Sanitation Foundation (NSF) water matrix which simulated the physicochemical characteristics of natural water. Water's pH significantly influences Cd and Ni adsorption efficiency which gradually increases when pH value rises from 5 to 9, while the corresponding one for Hg remains almost constant. Thermodynamic data showed a spontaneous and an exothermic nature weak-chemisorption (ΔΗ° = -17.5 ± 2 kJ/mol) of Cd, Ni, and Hg by TMFx. The determined ranking of adsorption affinity and selectivity (Cd > Ni > Hg) seems to be governed by the metals' speciation, as well as by hydration free energy, which is influenced, however, by their atomic radius. The lower adsorption capacity and selectivity of TMFx for Hg should be attributed both to uncharged species and to higher atomic radius. The similar Cd and Ni speciation in the NSF water matrix leads to the conclusion that the better affinity, selectivity, and adsorption kinetic of Cd versus Ni should be attributed to the lower hydration free energy of Cd which is in turn related to its higher atomic radius. The faster adsorption kinetic (Hg > Cd > Ni) of Hg may be attributed to the lower radius of its anhydrate species. Furthermore, TMFx showed high removal efficiency under continuous flow application in an adsorption bed setup. The determined uptake capacity (q RL) at equilibrium-breakthrough concentration equal to the drinking water regulation limit (RL) of each metal were q 1 = 2.5 μg Hg/mg TMFx, q 5 = 5.2 μg Cd/mg TMFx, and q 20 = 7.1 μg Ni/mg TMFx. Leaching tests of spent TMFx samples from the rapid small

  2. Reduction of adsorption capacity of coconut shell activated carbon for organic vapors due to moisture contents.

    PubMed

    Abiko, Hironobu; Furuse, Mitsuya; Takano, Tsuguo

    2010-01-01

    In occupational hygiene, activated carbon produced from coconut shell is a common adsorbent material for harmful substances including organic vapors due to its outstanding adsorption capacity and cost advantage. However, moisture adsorption of the carbon generally decreases the adsorption capacity for organic vapors. In a previous report, we prepared several coconut shell activated carbons which had been preconditioned by equilibration with moisture at different relative humidities and measured the breakthrough times for 6 kinds of organic vapor, in order to clarify the effect of preliminary moisture content in activated carbon on the adsorption capacity in detail. We found that the relative percent weight increase due to moisture adsorption of the carbon specimen had a quantitative effect, reducing the breakthrough time. In this report, we carried out further measurements of the effect of moisture content on the adsorption of 13 kinds of organic vapor, and investigated the relationship between moisture adsorption and the reduction of the breakthrough time of activated carbon specimens. We also applied the data to the Wood's breakthrough time estimation model which is an extension of the Wheeler-Jonas equation.

  3. Better adsorption capacity of SnO2 nanoparticles with different graphene addition

    NASA Astrophysics Data System (ADS)

    Paramarta, V.; Taufik, A.; Saleh, R.

    2016-11-01

    The adsorption capacity of SnO2 nanoparticle has been studied by graphene and nanographene platelets (NGP) additions using co-precipitation method. The crystalline phase, composition, and morphology of the samples are analyzed using X-Ray Diffraction (XRD), Energy Dispersive X-Ray (EDX), Fourier Transform Infrared Spectroscopy (FT-IR), and Transmission Electron Microscope (TEM). Tetragonal structure of SnO2 is shown for the nanoparticle and its composites. The presence of graphene and NGP is also confirmed. The adsorption capacity of the nanoparticle and its composites are analyzed by observing the degradation of methylene blue (MB) as the organic dye model using UV-Vis Spectroscopy. The result shows that SnO2 composite with graphene achieves higher adsorption capacity of about 20% than the composite with NGP. The fitting of equilibrium adsorption capacity result indicates that the adsorption mechanism of SnO2 composite with graphene tends to follow the Langmuir adsorption-isotherm model.

  4. Innate stimulatory capacity of high molecular weight transition metals Au (gold) and Hg (mercury).

    PubMed

    Rachmawati, Dessy; Alsalem, Inás W A; Bontkes, Hetty J; Verstege, Marleen I; Gibbs, Sue; von Blomberg, B M E; Scheper, Rik J; van Hoogstraten, Ingrid M W

    2015-03-01

    Nickel, cobalt and palladium ions can induce an innate immune response by triggering Toll-like receptor (TLR)-4 which is present on dendritic cells (DC). Here we studied mechanisms of action for DC immunotoxicity to gold and mercury. Next to gold (Na3Au (S2O3)2⋅2H2O) and mercury (HgCl2), nickel (NiCl2) was included as a positive control. MoDC activation was assessed by release of the pro-inflammatory mediator IL-8. Also PBMC were studied, and THP-1 cells were used as a substitution for DC for evaluation of cytokines and chemokines, as well as phenotypic, alterations in response to gold and mercury. Our results showed that both Na3Au (S2O3)2⋅2H2O and HgCl2 induce substantial release of IL-8, but not IL-6, CCL2 or IL-10, from MoDc, PBMC, or THP-1 cells. Also gold and, to a lesser extent mercury, caused modest dendritic cell maturation as detected by increased membrane expression of CD40 and CD80. Both metals thus show innate immune response capacities, although to a lower extent than reported earlier for NiCl2, CoCl2 and Na2 [PdCl4]. Importantly, the gold-induced response could be ascribed to TLR3 rather than TLR4 triggering, whereas the nature of the innate mercury response remains to be clarified. In conclusion both gold and mercury can induce innate immune responses, which for gold could be ascribed to TLR3 dependent signalling. These responses are likely to contribute to adaptive immune responses to these metals, as reflected by skin and mucosal allergies.

  5. [Determination and characterization on the capacity of humic acid for the reduction of divalent mercury].

    PubMed

    Jiang, Tao; Wet, Shi-Qiang; Li, Xue-Mei; Lu, Song; Li, Meng-Jie; Luo, Chang

    2012-01-01

    Reduction capacity (RC) has been recognized as an important parameter for evaluating the redox role of humic acid (HA). Thus, for understanding the capacity of HA for the reduction of mercury (Hg2+), chemical reduction capacity (CRC), microbial reduction capacity (MRC) and native reduction capacity (NRC) for mercury reduction by three types of HAs extracted from various sources (SH, TJ and JY) were measured respectively, following the pre-treatment of the HA samples by saturated hydrogen oscillation, soil solution incubation and the control (without any pretreatment). Three electron acceptors including mercuric chloride (HgCl2), mercuric nitrate [Hg(NO3)3] and ferric citrate (FeCit) as a reference were adapted respectively based on the Fe3+ reduction method. The principal results indicated that: (1) the capacity of HA for the reduction of Hg was significantly affected by various electron acceptors, with the RC values obtained under FeCit condition were all greatly higher than those in the conditions of Hg(NO3)2 and HgCl2, which suggested that the RC obtained using Fe3+ reduction method could exaggerate the actual capacity of HA for the reduction of Hg2+; (2) significant differences existed for the reduction capacity of Hg2+ by different HAs, with those of JY were the highest, which were (0.95 +/- 0.03) mmol(c) x mol(-1) (NRC), (5.95 +/- 0.63) mmol(c) x mol(-1) (CRC) and (6.26 +/- 0.51) mmol(c) x mol(-1) (MRC) respectively; (3) HA in solution forms had approximately 100% - 691.67% higher reduction capacity than those as solid forms. Meanwhile, through comparison of the differences among three RC indices, higher CRC and MRC values than NRC were observed, but no significant difference between CRC and MRC was concluded. Thus, CRC may not be applicable to comprehensively represent the real reduction capacity of HA for Hg reduction under microbial condition.

  6. Adsorption of mercury (II) from aqueous solutions using FeS and pyrite: A comparative study.

    PubMed

    Sun, Yue; Lv, Dan; Zhou, Jiasheng; Zhou, Xiaoxin; Lou, Zimo; Baig, Shams Ali; Xu, Xinhua

    2017-10-01

    In this study, a comparative evaluation of synthetic FeS and natural pyrite was performed to investigate their adsorptive potentials toward Hg(II) in aqueous system. Characterization analyses such as BET, SEM and TEM suggested that FeS had porous structures with abundant active sites, while pyrite with a hard and smooth surface relied mainly on surface adsorption to immobilize Hg(II). Results of batch tests revealed that FeS offered much greater Hg(II) maximum adsorption capacity (769.2 mg/g) as compared to pyrite (9.9 mg/g). Both iron sulfides showed high removal efficiency (>96%) with the initial Hg(II) concentration (1 mg/L) at pH = 7.0 ± 0.1, and the effluent could meet the permissible effluent concentration (<50 μg/L). Condition experiments (such as pH, co-ions) proved that the adaptive capacity of FeS was significantly higher than that of pyrite. A pseudo-second-order kinetic model was better able to illustrate the sorption kinetics on both FeS and pyrite (R(2) ≥ 0.9992). XRD and XPS analyses supported that precipitation, ion exchange and surface complexation were main reaction mechanisms involved in the adsorption process. In addition, it was also revealed that the structural changes of FeS before and after adsorption was much larger than pyrite. Findings from this study suggest FeS is a promising candidate for treatment of high-concentration Hg(II)-containing wastewater (<20 mg/L), while pyrite can be applied as a long-term adsorbing material in the immobilization of wastewater containing low Hg(II) concentration (<1 mg/L) due to its cost-effective property and local availability. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Memory effects on adsorption tubes for mercury vapor measurement in ambient air: elucidation, quantification, and strategies for mitigation of analytical bias.

    PubMed

    Brown, Richard J C; Kumar, Yarshini; Brown, Andrew S; Kim, Ki-Hyun

    2011-09-15

    The short- and long-term memory effects associated with measurements of mercury vapor in air using gold-coated silica adsorption tubes have been described. Data are presented to quantify these effects and to determine their dependence on certain relevant measurement parameters, such as number of heating cycles used for each analysis, age of adsorption tube, mass of mercury on adsorption tube, and the length of time between analyses. The results suggest that the long-term memory effect is due to absorption of mercury within the bulk gold in the adsorption tube, which may only be fully liberated by allowing enough time for this mercury to diffuse to the gold surface. The implications of these effects for air quality networks making these measurements routinely has been discussed, and recommendations have been made to ensure any measurement bias is minimized.

  8. Enhancement of the anionic dye adsorption capacity of clinoptilolite by Fe(3+)-grafting.

    PubMed

    Akgül, Murat

    2014-02-28

    In this paper, a batch system was applied to study the adsorption behavior of congo red (CR) on raw and modified clinoptilolites. Raw clinoptilolite (Raw-CL) was treated with Fe(NO3)3 in ethanol to obtain its iron-grafted form (Fe-CL). Adsorbents were characterized by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), energy dispersive X-ray spectroscopy (EDX), thermogravimetric/differential thermal analysis (TG/DTA), zeta-potential measurement and N2 gas adsorption-desorption techniques. Effects of the experimental parameters (initial pH, dye concentration, temperature and adsorption time) were investigated to find optimum conditions that result in highest adsorption capacity for CR removal. The obtained results suggest that the solution pH appears to be a key factor of the CR adsorption process. The maximum dye adsorption was achieved with Fe-CL adsorbent at pH ∼6.3 and the corresponding adsorption capacity was found to be 36.7mg/g, which is higher than that of its raw counterpart (16.9mg/g). A significant decrease in CR removal was given by Fe-CL between pH 7 and 11 opposite to Raw-CL which has nearly constant qe in the same pH range. The Fe(3+)-grafting increased the zeta potential of raw clinoptilolite, leading to a higher adsorption capacity compared to that of unfunctionalized adsorbent. Also, temperature change was found to have a significant effect on the adsorption process.

  9. Mercury adsorption on a carbon sorbent derived from fruit shell of Terminalia catappa.

    PubMed

    Inbaraj, B Stephen; Sulochana, N

    2006-05-20

    A carbonaceous sorbent derived from the fruit shell of Indian almond (Terminalia catappa) by sulfuric acid treatment was used for the removal of mercury(II) from aqueous solution. Sorption of mercury depends on the pH of the aqueous solution with maximum uptake occurring in the pH range of 5-6. The kinetics of sorption conformed well to modified second order model among the other kinetic models (pseudo first order and pseudo second order) tested. The Langmuir and Redlich-Peterson isotherm models defined the equilibrium data precisely compared to Freundlich model and the monolayer sorption capacity obtained was 94.43 mg/g. Sorption capacity increased with increase in temperature and the thermodynamic parameters, DeltaH degrees , DeltaS degrees and DeltaG degrees , indicated the Hg(II) sorption to be endothermic and spontaneous with increased randomness at the solid-solution interface. An optimum carbon dose of 4 g/l was required for the maximum uptake of Hg(II) from 30 mg/l and the mathematical relationship developed showed a correlation of 0.94 between experimental and calculated percentage removals for any carbon dose studied. About 60% of Hg(II) adsorbed was recovered from the spent carbon at pH 1.0, while 94% of it was desorbed using 1.0% KI solution.

  10. Correlation and prediction of adsorption capacity and affinity of aromatic compounds on carbon nanotubes.

    PubMed

    Wu, Wenhao; Yang, Kun; Chen, Wei; Wang, Wendi; Zhang, Jie; Lin, Daohui; Xing, Baoshan

    2016-01-01

    Adsorption of 22 nonpolar and polar aromatic compounds on 10 carbon nanotubes (CNTs) with various diameters, lengths and surface oxygen-containing group contents was investigated to develop predictive correlations for adsorption, using the isotherm fitting of Polanyi theory-based Dubinin-Ashtakhov (DA) model. Adsorption capacity of aromatic compounds on CNTs is negatively correlated with melting points of aromatic compounds, and surface oxygen-containing group contents and surface area ratios of mesopores to total pores of CNTs, but positively correlated with total surface area of CNTs. Adsorption affinity is positively correlated with solvatochromic parameters of aromatic compounds, independent of tube lengths and surface oxygen-containing group contents of CNTs, but negatively correlated with surface area ratios of mesopores to total pores of CNTs. The correlations of adsorption capacity and adsorption affinity with properties of both aromatic compounds and CNTs clearly have physical significance, can be used successfully with DA model to predict adsorption of aromatic compounds on CNTs from the well-known physiochemical properties of aromatic compounds (i.e., solvatochromic parameters, melting points) and CNTs (i.e., surface area and total acidic group contents), and thus can facilitate the environmental application of CNTs as sorbents and environmental risk assessment of both aromatic contaminants and CNTs.

  11. Mercury

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002476.htm Mercury To use the sharing features on this page, please enable JavaScript. This article discusses poisoning from mercury. This article is for information only. Do NOT ...

  12. Studies on adsorption of mercury from aqueous solution on activated carbons prepared from walnut shell.

    PubMed

    Zabihi, M; Haghighi Asl, A; Ahmadpour, A

    2010-02-15

    The adsorption ability of a powdered activated carbons (PAC) derived from walnut shell was investigated in an attempt to produce more economic and effective sorbents for the control of Hg(II) ion from industrial liquid streams. Carbonaceous sorbents derived from local walnut shell, were prepared by chemical activation methods using ZnCl(2) as activating reagents. Adsorption of Hg(II) from aqueous solutions was carried out under different experimental conditions by varying treatment time, metal ion concentration, pH and solution temperature. It was shown that Hg(II) uptake decreases with increasing pH of the solution. The proper choice of preparation conditions were resulted in microporous activated carbons with different BET surface areas of 780 (Carbon A, 1:0.5 ZnCl(2)) and 803 (Carbon B, 1:1 ZnCl(2))m(2)/g BET surface area. The monolayer adsorption capacity of these particular adsorbents were obtained as 151.5 and 100.9 mg/g for carbons A and B, respectively. It was determined that Hg(II) adsorption follows both Langmuir and Freundlich isotherms as well as pseudo-second-order kinetics.

  13. Carbon nanotube membranes with ultrahigh specific adsorption capacity for water desalination and purification.

    PubMed

    Yang, Hui Ying; Han, Zhao Jun; Yu, Siu Fung; Pey, Kin Leong; Ostrikov, Kostya; Karnik, Rohit

    2013-01-01

    Development of technologies for water desalination and purification is critical to meet the global challenges of insufficient water supply and inadequate sanitation, especially for point-of-use applications. Conventional desalination methods are energy and operationally intensive, whereas adsorption-based techniques are simple and easy to use for point-of-use water purification, yet their capacity to remove salts is limited. Here we report that plasma-modified ultralong carbon nanotubes exhibit ultrahigh specific adsorption capacity for salt (exceeding 400% by weight) that is two orders of magnitude higher than that found in the current state-of-the-art activated carbon-based water treatment systems. We exploit this adsorption capacity in ultralong carbon nanotube-based membranes that can remove salt, as well as organic and metal contaminants. These ultralong carbon nanotube-based membranes may lead to next-generation rechargeable, point-of-use potable water purification appliances with superior desalination, disinfection and filtration properties.

  14. High-Capacity and Photoregenerable Composite Material for Efficient Adsorption and Degradation of Phenanthrene in Water.

    PubMed

    Liu, Wen; Cai, Zhengqing; Zhao, Xiao; Wang, Ting; Li, Fan; Zhao, Dongye

    2016-10-18

    We report a novel composite material, referred to as activated charcoal supported titanate nanotubes (TNTs@AC), for highly efficient adsorption and photodegradation of a representative polycyclic aromatic hydrocarbon (PAH), phenanthrene. TNTs@AC was prepared through a one-step hydrothermal method, and is composed of an activated charcoal core and a shell of carbon-coated titanate nanotubes. TNTs@AC offered a maximum Langmuir adsorption capacity of 12.1 mg/g for phenanthrene (a model PAH), which is ∼11 times higher than the parent activated charcoal. Phenanthrene was rapidly concentrated onto TNTs@AC, and subsequently completely photodegraded under UV light within 2 h. The photoregenerated TNTs@AC can then be reused for another adsorption-photodegradation cycle without significant capacity or activity loss. TNTs@AC performed well over a wide range of pH, ionic strength, and dissolved organic matter. Mechanistically, the enhanced adsorption capacity is attributed to the formation of carbon-coated ink-bottle pores of the titanate nanotubes, which are conducive to capillary condensation; in addition, the modified microcarbon facilitates transfer of excited electrons, thereby inhibiting recombination of the electron-hole pairs, resulting in high photocatalytic activity. The combined high adsorption capacity, photocatalytic activity, and regenerability/reusability merit TNTs@AC a very attractive material for concentrating and degrading a host of micropollutants in the environment.

  15. Influence of clay mineral structure and surfactant nature on the adsorption capacity of surfactants by clays.

    PubMed

    Sánchez-Martín, M J; Dorado, M C; del Hoyo, C; Rodríguez-Cruz, M S

    2008-01-15

    Adsorption of three surfactants of different nature, Triton X-100 (TX100) (non-ionic), sodium dodecylsulphate (SDS) (anionic) and octadecyltrimethylammonium bromide (ODTMA) (cationic) by four layered (montmorillonite, illite, muscovite and kaolinite) and two non-layered (sepiolite and palygorskite) clay minerals was studied. The objective was to improve the understanding of surfactant behaviour in soils for the possible use of these compounds in remediation technologies of contaminated soils by toxic organic compounds. Adsorption isotherms were obtained using surfactant concentrations higher and lower than the critical micelle concentration (cmc). These isotherms showed different adsorption stages of the surfactants by the clay minerals, and were classified in different subgroups of the L-, S- or H-types. An increase in the adsorption of SDS and ODTMA by all clay minerals is observed up to the cmc of the surfactant in the equilibrium solution is reached. However, there was further TX100 adsorption when the equilibrium concentration was well above the cmc. Adsorption constants from Langmuir and Freundlich equations (TX100 and ODTMA) or Freundlich equation (SDS) were used to compare adsorption of different surfactants by clay minerals studied. These constants indicated the surfactant adsorption by clay minerals followed this order ODTMA>TX100>SDS. The adsorption of TX100 and ODTMA was higher by montmorillonite and illite, and the adsorption of SDS was found to be higher by kaolinite and sepiolite. Results obtained show the influence of clay mineral structure and surfactant nature on the adsorption capacity of surfactants by clays, and they indicate the interest to consider the soil mineralogical composition when one surfactant have to be selected in order to establish more efficient strategies for the remediation of soils and water contaminated by toxic organic pollutants.

  16. Investigation of Morphology and Hydrogen Adsorption Capacity of Disordered Carbons

    NASA Astrophysics Data System (ADS)

    He, Lilin; Melnichenko, Yuri; Gallego, Nidia; Contescu, Cristian

    2014-03-01

    We have applied small angle neutron scattering (SANS) technique to study the morphologies and hydrogen adsorption capabilities of wood-based ultramicroporous carbon and poly(furfuryl alcohol) derived carbon. The Polydispersed Spherical model and chord length analysis of the scattering profiles were performed to obtain morphological parameters such as average pore size and pore size distribution of the dry carbons, which agreed reasonably well with the independent gas sorption measurements. The hydrogen physisorbed in these two carbons at room temperature and moderate pressures was investigated by In-situ SANS measurements. The experimental data analyzed using a modified Kalliat model for decoupling scattering contributions from pores with different sizes indicates that the molecular hydrogen condenses preferentially in narrow micropores at all measured pressures, which supports the theoretical prediction by quantum mechanical and thermodynamical models.

  17. Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 1. Adsorption capacity and kinetics

    SciTech Connect

    Yu, Z.; Peldszus, S.; Huck, P.M.

    2009-03-01

    The adsorption of two representative PhACs (naproxen and carbamazepine) and one EDC (nonylphenol) were evaluated on two granular activated carbons (GAC) namely coal-based Calgon Filtrasorb 400 and coconut shell-based PICA CTIF TE. The primary objective was to investigate preloading effects by natural organic matter (NOM) on adsorption capacity and kinetics under conditions and concentrations (i.e., ng/L) relevant for drinking water treatment. Isotherms demonstrated that all compounds were significantly negatively impacted by NOM fouling. Adsorption capacity reduction was most severe for the acidic naproxen, followed by the neutral carbamazepine and then the more hydrophobic nonylphenol. The GAC with the wider pore size distribution had considerably greater NOM loading, resulting in lower adsorption capacity. Different patterns for the change in Freundlich KF and 1/n with time revealed different competitive mechanisms for the different compounds. Mass transport coefficients determined by short fixed-bed (SFB) tests with virgin and preloaded GAC demonstrated that film diffusion primarily controls mass transfer on virgin and preloaded carbon. Naproxen suffered the greatest deteriorative effect on kinetic parameters due to preloading, followed by carbamazepine, and then nonylphenol. A type of surface NOM/biofilm, which appeared to add an additional mass transfer resistance layer and thus reduce film diffusion, was observed. In addition, electrostatic interactions between NOM/biofilm and the investigated compounds are proposed to contribute to the reduction of film diffusion. A companion paper building on this work describes treatability studies in pilot-scale GAC adsorbers and the effectiveness of a selected fixed-bed model. 32 refs., 3 figs., 2 tabs.

  18. Non-Contact Analysis of the Adsorptive Ink Capacity of Nano Silica Pigments on a Printing Coating Base

    PubMed Central

    Jiang, Bo; Huang, Yu Dong

    2014-01-01

    Near infrared spectra combined with partial least squares were proposed as a means of non-contact analysis of the adsorptive ink capacity of recording coating materials in ink jet printing. First, the recording coating materials were prepared based on nano silica pigments. 80 samples of the recording coating materials were selected to develop the calibration of adsorptive ink capacity against ink adsorption (g/m2). The model developed predicted samples in the validation set with r2  = 0.80 and SEP  = 1.108, analytical results showed that near infrared spectra had significant potential for the adsorption of ink capacity on the recording coating. The influence of factors such as recording coating thickness, mass ratio silica: binder-polyvinyl alcohol and the solution concentration on the adsorptive ink capacity were studied. With the help of the near infrared spectra, the adsorptive ink capacity of a recording coating material can be rapidly controlled. PMID:25329464

  19. Non-contact analysis of the adsorptive ink capacity of nano silica pigments on a printing coating base.

    PubMed

    Jiang, Bo; Huang, Yu Dong

    2014-01-01

    Near infrared spectra combined with partial least squares were proposed as a means of non-contact analysis of the adsorptive ink capacity of recording coating materials in ink jet printing. First, the recording coating materials were prepared based on nano silica pigments. 80 samples of the recording coating materials were selected to develop the calibration of adsorptive ink capacity against ink adsorption (g/m2). The model developed predicted samples in the validation set with r2  = 0.80 and SEP = 1.108, analytical results showed that near infrared spectra had significant potential for the adsorption of ink capacity on the recording coating. The influence of factors such as recording coating thickness, mass ratio silica: binder-polyvinyl alcohol and the solution concentration on the adsorptive ink capacity were studied. With the help of the near infrared spectra, the adsorptive ink capacity of a recording coating material can be rapidly controlled.

  20. The effect of nitrogen doping on mercury oxidation/chemical adsorption on the CuCo2O4(110) surface: a molecular-level description.

    PubMed

    Mei, Zhijian; Fan, Maohong; Zhang, Ruiqing; Shen, Zhemin; Wang, Wenhua

    2014-07-14

    Based on density functional theory (DFT) calculations, the detailed mercury oxidation/chemical adsorption mechanisms on the N-doped CuCo2O4(110) surface are studied. The DFT calculations show that Ow (bonded with one Cu(2+) ion and one Co(3+) ion) is far more active than Os (bonded with three Co(3+) ions) and the mercury oxidation/chemical adsorption activation energy (Ea) on the virgin CuCo2O4(110) surface involving Ow is 0.85 eV. The physically adsorbed mercury overcomes the Ea and enters the energy well that plays an important role in mercury oxidation/chemical adsorption. Nitrogen doping can greatly increase the activity of Ow and decrease the activity of Os at the same time, which greatly affect the mercury oxidation/chemical adsorption abilities on the CuCo2O4(110) surface, and the Ea variation of mercury oxidation/chemical adsorption is as follows: 0.85 eV (virgin CuCo2O4(110)) → 0.76 eV (one N-doped CuCo2O4(110)) → 0.69 eV (two N-doped CuCo2O4(110)) → 0.48 eV (three N-doped CuCo2O4(110)). In addition, N-doping can decrease the adsorption energy of mercury and mercuric oxide. The effect of N-doping on the bonding mechanism of mercury adsorption on the CuCo2O4(110) surface is analyzed by the local density of state (LDOS) and the natural bonding orbital (NBO). The calculation results correspond well to the experimental data.

  1. Characteristics of fly ashes from full-scale coal-fired power plants and their relationship to mercury adsorption

    USGS Publications Warehouse

    Lu, Y.; Rostam-Abadi, M.; Chang, R.; Richardson, C.; Paradis, J.

    2007-01-01

    Nine fly ash samples were collected from the particulate collection devices (baghouse or electrostatic precipitator) of four full-scale pulverized coal (PC) utility boilers burning eastern bituminous coals (EB-PC ashes) and three cyclone utility boilers burning either Powder River Basin (PRB) coals or PRB blends,(PRB-CYC ashes). As-received fly ash samples were mechanically sieved to obtain six size fractions. Unburned carbon (UBC) content, mercury content, and Brunauer-Emmett-Teller (BET)-N2 surface areas of as-received fly ashes and their size fractions were measured. In addition, UBC particles were examined by scanning electron microscopy, high-resolution transmission microscopy, and thermogravimetry to obtain information on their surface morphology, structure, and oxidation reactivity. It was found that the UBC particles contained amorphous carbon, ribbon-shaped graphitic carbon, and highly ordered graphite structures. The mercury contents of the UBCs (Hg/UBC, in ppm) in raw ash samples were comparable to those of the UBC-enriched samples, indicating that mercury was mainly adsorbed on the UBC in fly ash. The UBC content decreased with a decreasing particle size range for all nine ashes. There was no correlation between the mercury and UBC contents of different size fractions of as-received ashes. The mercury content of the UBCs in each size fraction, however, generally increased with a decreasing particle size for the nine ashes. The mercury contents and surface areas of the UBCs in the PRB-CYC ashes were about 8 and 3 times higher than UBCs in the EB-PC ashes, respectively. It appeared that both the particle size and surface area of UBC could contribute to mercury capture. The particle size of the UBC in PRB-CYC ash and thus the external mass transfer was found to be the major factor impacting the mercury adsorption. Both the particle size and surface reactivity of the UBC in EB-PC ash, which generally had a lower carbon oxidation reactivity than the PRB

  2. Characterization and bisphenol A adsorption capacity of β-cyclodextrin-carboxymethylcellulose-based hydrogels.

    PubMed

    Kono, Hiroyuki; Onishi, Kenta; Nakamura, Taichi

    2013-10-15

    Novel hydrogel beads having molecular adsorption abilities were prepared from carboxymethylcellulose sodium salt (CMC) and β-cyclodextrin (β-CD) by suspension crosslinking, using ethylene glycol diglycidyl ether (EGDE) in basic medium as a crosslinking agent. FTIR and solid-state NMR spectroscopic analysis revealed that the amount of incorporated β-CD and crosslinking densities within the hydrogel bead structures are strongly dependent on the molar feed ratio of β-CD to CMC during preparation. The hydrogel beads showed water-swelling capacities of 70-200 mL/g-polymer, with decreases in capacity associated with increased amounts of β-CD incorporated in the gel structure. The hydrogel beads also showed a high adsorption capacity toward bisphenol A (BPA) in water. Batch BPA-adsorption experiments were analyzed employing Langmuir isotherm models; hydrogel bead adsorption isotherms for BPA could be fitted to the Langmuir model. The maximum BPA-adsorption among the prepared series of hydrogel beads amounted to 167 μmol g(-1). Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. [Surface characteristics of alkali modified activated carbon and the adsorption capacity of methane].

    PubMed

    Zhang, Meng-Zhu; Li, Lin; Liu, Jun-Xin; Sun, Yong-Jun; Li, Guo-Bin

    2013-01-01

    Coconut shell based activated carbon was modified by alkali with different concentrations. The surface structures of tested carbons were observed and analyzed by SEM and BET methods. Boehm's titration and SEM/EDS methods were applied to assay the functional groups and elements on the carbon surface. The adsorption of methane on tested carbons was investigated and adsorption behavior was described by the adsorption isotherms. Results showed that surface area and pore volume of modified carbon increased and surface oxygen groups decreased as the concentration of the alkali used increased, with no obvious change in pore size. When concentration of alkali was higher than 3.3 mol x L(-1), the specific surface area and pore volume of modified carbon was larger than that of original carbon. Methane adsorption capacity of alkali modified carbon increased 24%. Enlargement of surface area and pore volume, reduction of surface oxygen groups will benefit to enhance the methane adsorption ability on activated carbon. Adsorption behavior of methane followed the Langmuir isotherm and the adsorption coefficient was 163.7 m3 x mg(-1).

  4. Experimental and theoretical investigations of mercury adsorption on hematite (1-102) surfaces

    NASA Astrophysics Data System (ADS)

    Jung, J.; Wilcox, J.; Jew, A. D.; Rupp, E. C.; Brown, G. E.

    2013-12-01

    Fly ash is a primary byproduct of the coal combustion process. The release of fly ash into the environment and its use in consumer products are public health concerns because of the presence of toxic trace metals and metalloids, such as mercury (Hg), selenium (Se), and arsenic (As), which may exist as components of fly ash, partition onto fly ash as it cools, or is lost to the environment through smoke stacks in a vapor phase. Therefore, it is important to understand the components of fly ash and their interaction with trace metals. In this study, calculations using density functional theory (DFT) were carried out in conjunction with experimental studies to investigate the interaction between Hg and hematite, an important mineral component of fly ash. Our experimental study, designed to simulate Hg sorption in a coal-fired power plant exhaust system, involved exposure of the fine fraction of bituminous coal fly ash (≤ 0.1 μm) to methane combustion flue gas, supplemented with SO2, NOx, HCl, and Hg in a packed-bed reactor. Sorption reaction products were characterized by synchrotron-based x-ray fluorescence mapping (s-XRF), x-ray diffraction (XRD), and extended x-ray absorption fine structure (EXAFS) spectroscopy. Preliminary s-XRF results showed that Hg in the sample is correlated with Fe, S, Cl, Br, and to a lesser extent with Se and As. From the XRD analysis, the dominant mineral phases detected were quartz, iron oxide (hematite), and various sulfate-bearing cements. Based on the experimental results, DFT studies were carried out to investigate the adsorption of Hg on hematite (α-Fe2O3) (1-102) surfaces. The two α-Fe2O3 (1-102) surfaces modeled consisted of two different surface terminations: (1) M2-clean, which corresponds to the oxygen terminated r-cut surface with the first layer of cations removed and no hydroxyl group and (2) M2-OH2-OH which has bihydroxylated top oxygen atoms and a second layer of hydroxylated oxygen atoms. These surface terminations

  5. Effect of purity on adsorption capacities of a Mars-like clay mineral at different pressures

    NASA Technical Reports Server (NTRS)

    Jenkins, Traci; Mcdoniel, Bridgett; Bustin, Roberta; Allton, Judith H.

    1992-01-01

    There has been considerable interest in adsorption of carbon dioxide on Marslike clay minerals. Some estimates of the carbon dioxide reservoir capacity of the martian regolith were calculated from the amount of carbon dioxide adsorbed on the ironrich smectite nontronite under martian conditions. The adsorption capacity of pure nontronite could place upper limits on the regolith carbon dioxide reservoir, both at present martian atmospheric pressure and at the postulated higher pressures required to permit liquid water on the surface. Adsorption of carbon dioxide on a Clay Mineral Society standard containing nontronite was studied over a wide range of pressures in the absence of water. Similar experiments were conducted on the pure nontronite extracted from the natural sample. Heating curves were obtained to help characterize and determine the purity of the clay sample.

  6. Effect of purity on adsorption capacities of a Mars-like clay mineral at different pressures

    NASA Technical Reports Server (NTRS)

    Jenkins, Traci; Mcdoniel, Bridgett; Bustin, Roberta; Allton, Judith H.

    1992-01-01

    There has been considerable interest in adsorption of carbon dioxide on Marslike clay minerals. Some estimates of the carbon dioxide reservoir capacity of the martian regolith were calculated from the amount of carbon dioxide adsorbed on the ironrich smectite nontronite under martian conditions. The adsorption capacity of pure nontronite could place upper limits on the regolith carbon dioxide reservoir, both at present martian atmospheric pressure and at the postulated higher pressures required to permit liquid water on the surface. Adsorption of carbon dioxide on a Clay Mineral Society standard containing nontronite was studied over a wide range of pressures in the absence of water. Similar experiments were conducted on the pure nontronite extracted from the natural sample. Heating curves were obtained to help characterize and determine the purity of the clay sample.

  7. Assessment of CO₂ adsorption capacity on activated carbons by a combination of batch and dynamic tests.

    PubMed

    Balsamo, Marco; Silvestre-Albero, Ana; Silvestre-Albero, Joaquín; Erto, Alessandro; Rodríguez-Reinoso, Francisco; Lancia, Amedeo

    2014-05-27

    In this work, batch and dynamic adsorption tests are coupled for an accurate evaluation of CO2 adsorption performance of three different activated carbons (AC) obtained from olive stones by chemical activation followed by physical activation with CO2 at varying times (i.e., 20, 40, and 60 h). Kinetic and thermodynamic CO2 adsorption tests from simulated flue gas at different temperatures and CO2 pressures are carried out under both batch (a manometric equipment operating with pure CO2) and dynamic (a lab-scale fixed-bed column operating with a CO2/N2 mixture) conditions. The textural characterization of the AC samples shows a direct dependence of both micropore and ultramicropore volume on the activation time; hence, AC60 has the higher contribution. The adsorption tests conducted at 273 and 293 K showed that when CO2 pressure is lower than 0.3 bar, the lower the activation time, the higher CO2 adsorption capacity; a ranking of ω(eq)(AC20) > ω(eq)(AC40) > ω(eq)(AC60) can be exactly defined when T = 293 K. This result is likely ascribed to the narrower pore size distribution of the AC20 sample, whose smaller pores are more effective for CO2 capture at higher temperature and lower CO2 pressure, the latter representing operating conditions of major interest for decarbonation of flue gas effluent. Moreover, the experimental results obtained from dynamic tests confirm the results derived from the batch tests in terms of CO2 adsorption capacity. It is important to highlight the fact that the adsorption of N2 on the synthesized AC samples can be considered to be negligible. Finally, the importance of proper analysis for data characterization and adsorption experimental results is highlighted for the correct assessment of the CO2 removal performance of activated carbons at different CO2 pressures and operating temperatures.

  8. Mercury reduction and cell-surface adsorption by Geobacter sulfurreducens PCA.

    PubMed

    Hu, Haiyan; Lin, Hui; Zheng, Wang; Rao, Balaji; Feng, Xinbin; Liang, Liyuan; Elias, Dwayne A; Gu, Baohua

    2013-10-01

    Both reduction and surface adsorption of mercuric mercury [Hg(II)] are found to occur simultaneously on G. sulfurreducens PCA cells under dark, anaerobic conditions. Reduction of Hg(II) to elemental Hg(0) initially follows a pseudo-first order kinetics with a half-life of <2 h in the presence of 50 nM Hg(II) and 10(11) cells L(-1) in a phosphate buffer (pH 7.4). Multiple gene deletions of the outer membrane cytochromes in this organism resulted in a decrease in reduction rate from ∼0.3 to 0.05 h(-1), and reduction was nearly absent with heat-killed cells or in the cell filtrate. Adsorption of Hg(II) by cells is found to compete with, and thus inhibit, Hg(II) reduction. Depending on the Hg to cell ratio, maximum Hg(II) reduction was observed at about 5 × 10(-19) mol Hg cell(-1), but reduction terminated at a low Hg to cell ratio (<10(-20) mol Hg cell(-1)). This inhibitory effect is attributed to bonding between Hg(II) and the thiol (-SH) functional groups on cells and validated by experiments in which the sorbed Hg(II) was readily exchanged by thiols (e.g., glutathione) but not by carboxylate compounds such as ethylenediamine-tetraacetate (EDTA). We suggest that coupled Hg(II)-cell interactions, i.e., reduction and surface binding, could be important in controlling Hg species transformation and bioavailability and should therefore be considered in microbial Hg(II) uptake and methylation studies.

  9. Adsorption and oxidation of elemental mercury over Ce-MnOx/Ti-PILCs.

    PubMed

    He, Chuan; Shen, Boxiong; Chen, Jianhong; Cai, Ji

    2014-07-15

    A series of innovative Ce-Mn/Ti-pillared-clay (Ce-Mn/Ti-PILC) catalysts combining the advantages of PILCs and Ce-Mn were investigated for elemental mercury (Hg0) capture at 100-350 °C in the absence of HCl in the flue gas. The fresh and used catalysts were characterized by scanning electron microscopy (SEM), nitrogen adsorption-desorption, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The catalyst characterization indicated that the 6%Ce-6%MnOx/Ti-PILC catalyst possessed a large specific surface area and high dispersion of Ce and Mn on the surface. The experimental results indicated that the 6%Ce-6%MnOx/Ti-PILC catalyst exhibited high Hg0 capture (>90%) at 100-350 °C. During the first stage of the reaction, the main Hg0 capture mechanism for the catalyst was adsorption. As the reaction proceeded, the Hg0 oxidation ability was substantially enhanced. Both the hydroxyl oxygen and the lattice oxygen on the surface of the catalysts participated in Hg0 oxidation. At a low temperature (150 °C), the hydroxyl oxygen and lattice oxygen from Ce4+→Ce3+ and Mn3+→Mn2+ on the surface contributed to Hg0 oxidation. However, at a high temperature (250 °C), the hydroxyl oxygen and lattice oxygen from Mn4+→Mn3+ contributed to Hg0 oxidation. Hg0 oxidation was preferred at a high temperature. The 6%Ce-6%MnOx/Ti-PILC catalyst was demonstrated to a good Hg0 adsorbent and catalytic oxidant in the absence of HCl in the flue gas.

  10. The effect of natural organic matter on the adsorption of mercury to bacterial cells

    NASA Astrophysics Data System (ADS)

    Dunham-Cheatham, Sarrah; Mishra, Bhoopesh; Myneni, Satish; Fein, Jeremy B.

    2015-02-01

    We investigated the ability of non-metabolizing Bacillus subtilis, Shewanella oneidensis MR-1, and Geobacter sulfurreducens bacterial species to adsorb mercury in the absence and presence of Suwanee River fulvic acid (FA). Bulk adsorption and X-ray absorption spectroscopy (XAS) experiments were conducted at three pH conditions, and the results indicate that the presence of FA decreases the extent of Hg adsorption to biomass under all of the pH conditions studied. Hg XAS results show that the presence of FA does not alter the binding environment of Hg adsorbed onto the biomass regardless of pH or FA concentration, indicating that ternary bacteria-Hg-FA complexes do not form to an appreciable extent under the experimental conditions, and that Hg binding on the bacteria is dominated by sulfhydryl binding. We used the experimental results to calculate apparent partition coefficients, Kd, for Hg under each experimental condition. The calculations yield similar coefficients for Hg onto each of the bacterial species studies, suggesting there is no significant difference in Hg partitioning between the three bacterial species. The calculations also indicate similar coefficients for Hg-bacteria and Hg-FA complexes. S XAS measurements confirm the presence of sulfhydryl sites on both the FA and bacterial cells, and demonstrate the presence of a wide range of S moieties on the FA in contrast to the bacterial biomass, whose S sites are dominated by thiols. Our results suggest that although FA can compete with bacterial binding sites for aqueous Hg, because of the relatively similar partition coefficients for the types of sorbents, the competition is not dominated by either bacteria or FA unless the concentration of one type of site greatly exceeds that of the other.

  11. Mercury reduction and cell-surface adsorption by Geobacter sulfurreducens PCA

    SciTech Connect

    Hu, Haiyan; Lin, Hui; Zheng, Wang; Feng, Xinbin; Liang, Liyuan; Elias, Dwayne A; Gu, Baohua

    2013-01-01

    Both reduction and surface adsorption of mercuric mercury [Hg(II)] are found to occur simultaneously on G. sulfurreducens PCA cells under dark, anaerobic conditions. Reduction of Hg(II) to elemental Hg(0) initially follows a pseudo-first order kinetics with a half-life of < 2 h in the presence of 50 nM Hg(II) and 1011 cells L-1 in a phosphate buffer (pH 7.4). Multiple gene deletions of the outer membrane cytochromes in this organism resulted in decrease in reduction rate from ~ 0.3 to 0.05 h-1, and reduction was nearly absent with heat-killed cells or in the cell filtrate. Adsorption of Hg(II) by cells is found to compete with, and thus inhibit, Hg(II) reduction. Depending on the Hg to cell ratio, maximum Hg(II) reduction was observed at about 5 10-19 mol Hg cell-1, but reduction terminated at a low Hg to cell ratio (< 10-20 mol Hg cell-1). This inhibitory effect is attributed to strong binding between Hg(II) and the thiol ( SH) functional groups on cells and validated by experiments in which the sorbed Hg(II) was readily exchanged by thiols (e.g., glutathione) but not by carboxylic ligands such as ethylenediaminetetraacetate (EDTA). We suggest that coupled Hg(II)-cell interactions, i.e., reduction and surface binding, could be important in controlling Hg species transformation and bioavailability and should therefore be considered in microbial Hg(II) uptake and methylation studies.

  12. In vitro study of the effect of dog food on the adsorptive capacity of activated charcoal.

    PubMed

    Wilson, Helen E; Humm, Karen R

    2013-01-01

    To evaluate the effect of dog food on the adsorptive capacity of activated charcoal. In vitro laboratory study. University veterinary teaching hospital. None. None. A fixed quantity of acetaminophen (50 mg) was added to a fixed quantity of activated charcoal (1 g), mixed with varying amounts of dog food (2-14 g). The admixture was agitated for 5 minutes, incubated at 38.5°C for 1 hour and then centrifuged for 30 minutes. The concentration of residual, nonadsorbed acetaminophen in the supernatant was quantitatively assayed by reverse phase high-pressure liquid chromatography with ultraviolet detection. Data were tested by linear regression analysis and statistical significance was set at P < 0.05. A statistically significant reduction in the adsorptive capacity of activated charcoal was demonstrated with increasing amounts of dog food (R(2) = 0.54; P = 0.0018). However, all measurements of residual acetaminophen were less than 100 mg/L, representing a reduction in acetaminophen concentration of more than 98.6%. The addition of dog food to activated charcoal reduces its total adsorptive capacity for acetaminophen. However, this reduction in adsorptive capacity is unlikely to be clinically significant in the presence of both the formulation of dog food and the ratio of dog food to charcoal used in this study. © Veterinary Emergency and Critical Care Society 2013.

  13. Ammonia adsorption capacity of biomass and animal-manure derived biochars

    USDA-ARS?s Scientific Manuscript database

    The objective of this research was to characterize and investigate ammonia and hydrogen sulfide gas adsorption capacities of low- and high-temperature biochars made from wood shavings and chicken litter. The biochar samples were activated with steam or phosphoric acid. The specific surface areas and...

  14. Fugitive gas adsorption capacity of biomass and animal-manure derived biochars

    USDA-ARS?s Scientific Manuscript database

    This research characterized and investigated ammonia and hydrogen sulfide gas adsorption capacities of low- and high-temperature biochars made from wood shavings and chicken litter. The biochar samples were activated with steam or phosphoric acid. The specific surface areas and pore volumes of the a...

  15. MnOx/Graphene for the Catalytic Oxidation and Adsorption of Elemental Mercury.

    PubMed

    Xu, Haomiao; Qu, Zan; Zong, Chenxi; Huang, Wenjun; Quan, Fuquan; Yan, Naiqiang

    2015-06-02

    MnOx/graphene composites were prepared and employed to enhance the performance of manganese oxide (MnOx) for the capture of elemental mercury (Hg(0)) in flue gas. The composites were characterized using FT-IR, XPS, XRD, and TEM, and the results showed that the highly dispersed MnOx particles could be readily deposited on graphene nanosheets via hydrothermal process described here. Graphene appeared to be an ideal support for MnOx particles and electron transfer channels in the catalytic oxidation of Hg(0) at a high efficiency. Thus, MnOx/graphene-30% sorbents exhibited an Hg(0) removal efficiency of greater than 90% at 150 °C under 4% O2, compared with the 50% removal efficiency of pure MnOx. The mechanism of Hg(0) capture is discussed, and the main Hg(0) capture mechanisms of MnOx/graphene were catalytic oxidation and adsorption. Mn is the main active site for Hg(0) catalytic oxidation, during which high valence Mn (Mn(4+) or Mn(3+)) is converted to low valence Mn (Mn(3+) or Mn(2+)). Graphene enhanced the electrical conductivity of MnOx, which is beneficial for catalytic oxidation. Furthermore, MnOx/graphene exhibited an excellent regenerative ability, and is a promising sorbent for capturing Hg(0).

  16. Influence of the inherent properties of drinking water treatment residuals on their phosphorus adsorption capacities.

    PubMed

    Bai, Leilei; Wang, Changhui; He, Liansheng; Pei, Yuansheng

    2014-12-01

    Batch experiments were conducted to investigate the phosphorus (P) adsorption and desorption on five drinking water treatment residuals (WTRs) collected from different regions in China. The physical and chemical characteristics of the five WTRs were determined. Combined with rotated principal component analysis, multiple regression analysis was used to analyze the relationship between the inherent properties of the WTRs and their P adsorption capacities. The results showed that the maximum P adsorption capacities of the five WTRs calculated using the Langmuir isotherm ranged from 4.17 to 8.20mg/g at a pH of 7 and further increased with a decrease in pH. The statistical analysis revealed that a factor related to Al and 200 mmol/L oxalate-extractable Al (Alox) accounted for 36.5% of the variations in the P adsorption. A similar portion (28.5%) was attributed to an integrated factor related to the pH, Fe, 200 mmol/L oxalate-extractable Fe (Feox), surface area and organic matter (OM) of the WTRs. However, factors related to other properties (Ca, P and 5 mmol/L oxalate-extractable Fe and Al) were rejected. In addition, the quantity of P desorption was limited and had a significant negative correlation with the (Feox+Alox) of the WTRs (p<0.05). Overall, WTRs with high contents of Alox, Feox and OM as well as large surface areas were proposed to be the best choice for P adsorption in practical applications.

  17. Effect of surface area and chemisorbed oxygen on the SO2 adsorption capacity of activated char

    USGS Publications Warehouse

    Lizzio, A.A.; DeBarr, J.A.

    1996-01-01

    The objective of this study was to determine whether activated char produced from Illinois coal could be used effectively to remove sulfur dioxide from coal combustion flue gas. Chars were prepared from a high-volatile Illinois bituminous coal under a wide range of pyrolysis and activation conditions. A novel char preparation technique was developed to prepare chars with SO2 adsorption capacities significantly greater than that of a commercial activated carbon. In general, there was no correlation between SO2 adsorption capacity and surface area. Temperature-programmed desorption (TPD) was used to determine the nature and extent of carbon-oxygen (C-O) complexes formed on the char surface. TPD data revealed that SO2 adsorption was inversely proportional to the amount of C-O complex. The formation of a stable C-O complex during char preparation may have served only to occupy carbon sites that were otherwise reactive towards SO2 adsorption. A fleeting C(O) complex formed during SO2 adsorption is postulated to be the reaction intermediate necessary for conversion of SO2 to H2SO4. Copyright ?? 1996 Elsevier Science Ltd.

  18. Nanosheet-structured boron nitride spheres with a versatile adsorption capacity for water cleaning.

    PubMed

    Liu, Fei; Yu, Jie; Ji, Xixi; Qian, Muqi

    2015-01-28

    Here, we report the synthesis of nanosheet-structured boron nitride spheres (NSBNSs) by a catalyzing thermal evaporation method from solid B powders. The NSBNSs consist of radially oriented ultrathin nanosheets with the sheet edges oriented on the surface. Formation of this unique structure occurs only at a certain reaction temperature. The diameter from 4 μm to 700 nm and the nanosheet thickness from 9.1 to 3.1 nm of the NSBNSs can be well-controlled by appropriately changing the mass ratio of boron powders and catalyst. The NSBNSs possess versatile adsorption capacity, exhibiting excellent adsorption performance for oil, dyes, and heavy metal ions from water. The oil uptake reaches 7.8 times its own weight. The adsorption capacities for malachite green and methylene blue are 324 and 233 mg/g, while those for Cu(2+), Pb(2+), and Cd(2+) are 678.7, 536.7, and 107.0 mg/g, respectively. The adsorption capacities of the NSBNSs for Cu(2+) and Pb(2+) are higher or much higher than those of the adsorbents reported previously. These results demonstrate the great potential of NSBNSs for water treatment and cleaning.

  19. Effect of impregnation protocol on physical characteristics and adsorptive properties of sulfur impregnated carbon for vapor-phase mercury

    SciTech Connect

    Liu, W.; Korpiel, J.A.; Vidic, R.D.

    1997-12-31

    Removal efficiency of commercially available sulfur-impregnated carbon (HGR) and bituminous coal-based activated carbon impregnated with sulfur at 250 C, 400 C and 600 C (BPL-S) for vapor-phase elemental mercury was evaluated under various process conditions. Based on the fixed-bed breakthrough experiments, both HGR and BPL-S carbon exhibited improved mercury removal efficiency compared to the virgin carbon (BPL). However, the BPL-S series had higher mercury uptake capacity than that of HGR for the influent mercury concentration of 55 g/m{sup 3} and at the operating temperature of 140 C. For the BPL-S series, impregnation temperature was an important factor which affected the capacity for mercury uptake. BPL-S impregnated at 600 C (BPL-S-600) had the highest removal capacity, while BPL-S-400 exhibited slightly lower capacity. BPL-S-250 exhibited significantly lower capacity when compared to BPL-S-600 and BPL-S-400. The actual sulfur content for HGR and BPL-S series were almost the same (10%), except BPL-S-250 which had much higher sulfur content of 36%. Specific surface area, as determined by the BET method, and bonding between sulfur and carbon, as determined by thermogravimetric analysis (TGA), were also dependent on the impregnation procedure. Higher impregnation temperatures promote more uniform distribution of low molecular weight sulfur allotropes on the carbon surface. Pore size distribution study showed the detailed micro-structure of these activated carbons. Most of the pores of HGR carbon have radius between 15--24 , while the radius of BPL-S pores was between 15--35 . As the impregnation temperature decreases, the portion of larger pores also decreases from BPL-S-600 to BPL-S-250.

  20. 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.

  1. 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.

  2. Novel biosorbent with high adsorption capacity prepared by chemical modification of white pine (Pinus durangensis) sawdust. Adsorption of Pb(II) from aqueous solutions.

    PubMed

    Salazar-Rabago, J J; Leyva-Ramos, R

    2016-03-15

    The natural sawdust (NS) from white pine (Pinus durangensis) was chemically modified by a hydrothermal procedure using citric, malonic and tartaric acids. The adsorption capacity of modified sawdust (MS) towards Pb(II) was considerably enhanced due to the introduction of carboxylic groups on the surface of MS during the modification, and the adsorption capacity was almost linearly dependent on the concentration of carboxylic sites. The NS surface was acidic, and the MS surface became more acidic after the modification. At T = 25 °C and pH = 5, the maximum adsorption capacity of the optimal MS towards Pb(II) was 304 mg/g, which is exceptionally high compared to NS and other MS reported previously. The adsorption capacity of MS was considerably reduced from 304 to 154 mg/g by decreasing the solution pH from 5 to 3 due to electrostatic interactions. The adsorption of Pb(II) on MS was reversible at pH = 2, but not at pH = 5. The contribution percentage of ion exchange to the overall adsorption capacity ranged from 70 to 99% and 10-66% at the initial pH of 3 and 5, respectively. Hence, the adsorption of Pb(II) on MS was mainly due to ion exchange at pH = 3 and to both ion exchange and electrostatic attraction at pH = 5.

  3. Preparation and characterization of a hierarchical porous char from sewage sludge with superior adsorption capacity for toluene by a new two-step pore-fabricating process.

    PubMed

    Kong, Lingjun; Xiong, Ya; Tian, Shuanghong; Luo, Rongshu; He, Chun; Huang, Haibao

    2013-10-01

    A kind of hierarchical porous char (SCCA/Zn) was prepared from sewage sludge by a new two-step pore-fabricating process coupling citric acid (CA) with ZnCl2 in a pyrolysis process. The char was characterized by element analysis, N2-adsorption and mercury intrusion measurement etc. It is found that coupling CA and ZnCl2 can synergistically fabricate pores in the pyrolysis process, resulting in a hierarchical porous char, SCCA/Zn, with the largest SBET of 867.6 m(2) g(-1) due to the fact that the former contributes to the fabrication of macro-pores, which provides more space for fabricating meso- and micro-pores by ZnCl2 activation. Although the SBET of SCCA/Zn was 15% less than that of activated carbon fiber (ACF, SBET=999.5 m(2) g(-1)), SCCA/Zn had a higher toluene adsorption capacity (0.83 g g(-1)) than ACF. The inconsistence between their SBET and adsorption capacity can be ascribed to the strong hydrophobic property of SCCA/Zn.

  4. An Adsorption Capacity Study of Supercritical CO2 on Zeolite, Illite and Organic-Rich Shales

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Prasad, M.

    2016-12-01

    CO2 injection into reservoirs will change the state of stress in both reservoir and caprock formations due to poro-mechanical, thermal and chemical effects. As a result of the induced stress, the caprock can be mechanically damaged, pre-existing sealing faults and fractures can be re-activated, or new fracture systems can be created. It is the main objective of this study to determine the behavior of intact and fractured caprocks when exposed to supercritical CO2 at elevated pressures, including the characterization of the physical, chemical and geomechanical processes associated with fluid flow and storage in these systems. Hereby, an envisioned experimental setup allows high pressure, super-critical CO2 adsorption and desorption isotherm measurements on powdered rock samples is designed. Zeolite, illite and shale samples with different maturity levels are used as adsorbent to perform CO2 adsorption experiment to study the corresponding adsorption capacities.

  5. Strengthening of Graphene Aerogels with Tunable Density and High Adsorption Capacity towards Pb2+

    PubMed Central

    Han, Zhuo; Tang, Zhihong; Shen, Shuling; Zhao, Bin; Zheng, Guangping; Yang, Junhe

    2014-01-01

    Graphene aerogels (GAs) with high mechanical strength, tunable density and volume have been prepared only via soaking graphene hydrogels (GHs) in ammonia solution. The density and volume of the obtained GAs are controlled by adjusting the concentration of ammonia solution. Although volume of the GAs decreases with increasing the concentration of ammonia solution, its specific surface area maintains at about 350 m2 g−1, and the inner structure changes to radial after ammonia solution treatment. Thus, GAs are particularly suitable for the adsorption and energy storage applications owing to their high specific surface area and unique porous structure. The adsorption capacity of GAs for Pb2+ from aqueous solution maintains at about 80 mg g−1, which could reach as high as 5000 g m−3 per unit volume and they can be separated easily from water after adsorption. PMID:24848100

  6. A Porous Aromatic Framework Constructed from Benzene Rings Has a High Adsorption Capacity for Perfluorooctane Sulfonate

    PubMed Central

    Luo, Qin; Zhao, Changwei; Liu, Guixia; Ren, Hao

    2016-01-01

    A low-cost and easily constructed porous aromatic framework (PAF-45) was successfully prepared using the Scholl reaction. PAF-45 was, for the first time, used to remove perfluorooctane sulfonate (PFOS) from aqueous solution. Systematic experiments were performed to determine the adsorption capacity of PAF-45 for PFOS and to characterize the kinetics of the adsorption process. The adsorption of PFOS onto PAF-45 reached equilibrium in 30 min, and the adsorption capacity of PAF-45 for PFOS was excellent (5847 mg g−1 at pH 3). The amount of PFOS adsorbed by PAF-45 increased significantly as the cation (Na+, Mg2+, or Fe3+) concentration increased, which probably occurred because the cations enhanced the interactions between the negatively charged PFOS molecules and the positively charged PAF-45 surface. The cations Na+, Mg2+, and Fe3+ were found to form complexes with PFOS anions in solution. Density functional theory was used to identify the interactions between PFOS and Na+, Mg2+, and Fe3+. We expect that materials of the same type as PAF-45 could be useful adsorbents for removing organic pollutants from industrial wastewater and contaminated surface water. PMID:26843015

  7. Activated carbons prepared from wood particleboard wastes: characterisation and phenol adsorption capacities.

    PubMed

    Girods, P; Dufour, A; Fierro, V; Rogaume, Y; Rogaume, C; Zoulalian, A; Celzard, A

    2009-07-15

    The problems of valorisation of particleboard wastes on one hand, and contamination of aqueous effluents by phenolic compounds on the other hand, are simultaneously considered in this work. Preparation of activated carbons from a two steps thermo-chemical process, formerly designed for generating combustible gases, is suggested. The resultant carbonaceous residue is activated with steam at 800 degrees C. Depending on the preparation conditions, surface areas within the range 800-1300 m(2)/g are obtained, close to that of a commercial activated carbon (CAC) specially designed for water treatment and used as a reference material. The present work shows that particleboard waste-derived activated carbons (WAC) are efficient adsorbents for the removal of phenol from aqueous solutions, with maximum measured capacities close to 500 mg/g. However, most of times, the adsorption capacities are slightly lower than that of the commercial material in the same conditions, i.e., at equilibrium phenol concentrations below 300 ppm. Given the extremely low cost of activated carbons prepared from particleboard waste, it should not be a problem to use it in somewhat higher amounts than what is required with a more expensive commercial material. Phenol adsorption isotherms at 298 K were correctly fitted by various equations modelling type I and type II isotherms for CAC and WAC, respectively. Phenol adsorption isotherms of type II were justified by a 3-stages adsorption mechanism.

  8. A Porous Aromatic Framework Constructed from Benzene Rings Has a High Adsorption Capacity for Perfluorooctane Sulfonate

    NASA Astrophysics Data System (ADS)

    Luo, Qin; Zhao, Changwei; Liu, Guixia; Ren, Hao

    2016-02-01

    A low-cost and easily constructed porous aromatic framework (PAF-45) was successfully prepared using the Scholl reaction. PAF-45 was, for the first time, used to remove perfluorooctane sulfonate (PFOS) from aqueous solution. Systematic experiments were performed to determine the adsorption capacity of PAF-45 for PFOS and to characterize the kinetics of the adsorption process. The adsorption of PFOS onto PAF-45 reached equilibrium in 30 min, and the adsorption capacity of PAF-45 for PFOS was excellent (5847 mg g‑1 at pH 3). The amount of PFOS adsorbed by PAF-45 increased significantly as the cation (Na+, Mg2+, or Fe3+) concentration increased, which probably occurred because the cations enhanced the interactions between the negatively charged PFOS molecules and the positively charged PAF-45 surface. The cations Na+, Mg2+, and Fe3+ were found to form complexes with PFOS anions in solution. Density functional theory was used to identify the interactions between PFOS and Na+, Mg2+, and Fe3+. We expect that materials of the same type as PAF-45 could be useful adsorbents for removing organic pollutants from industrial wastewater and contaminated surface water.

  9. Modified inverse micelle synthesis for mesoporous alumina with a high D4 siloxane adsorption capacity

    SciTech Connect

    Zhong, Wei; Jiang, Ting; Jafari, Tahereh; Poyraz, Altug S.; Wu, Wei; Kriz, David A.; Du, Shoucheng; Biswas, Sourav; Thompson Pettes, Michael; Suib, Steven L.

    2016-10-18

    In this work, mesoporous aluminas (MAs) with uniform and monomodal pores were fabricated via a modified inverse micelle synthesis method, using a non-polar solvent (to minimize the effect of water content) and short reaction time (for a fast evaporation process). The effects of reaction times (4–8 h), surfactant chain lengths (non-ionic surfactants), and calcination temperatures and hold times (450–600 °C; 1–4 h) on the textural properties of MA were studied. Additionally, the targeted pore sizes of MA were obtained in the range of 3.1–5.4 nm by adjusting the surfactant and reaction time. The surface area and pore volume were controlled by the calcination temperature and hold time while maintaining the thermal stability of the materials. The tuned MA of the large mesopore volume achieved 168 mg/g octamethylcyclotetrasiloxane (D4 siloxane) adsorption capacity, a 32% improvement compared to commercially activated alumina. Finally, after three adsorption recycles, the synthesized MA still maintained approximate 85% of its original adsorption capacity, demonstrating a sustainable adsorption performance and high potential for related industrial applications.

  10. Modified inverse micelle synthesis for mesoporous alumina with a high D4 siloxane adsorption capacity

    DOE PAGES

    Zhong, Wei; Jiang, Ting; Jafari, Tahereh; ...

    2016-10-18

    In this work, mesoporous aluminas (MAs) with uniform and monomodal pores were fabricated via a modified inverse micelle synthesis method, using a non-polar solvent (to minimize the effect of water content) and short reaction time (for a fast evaporation process). The effects of reaction times (4–8 h), surfactant chain lengths (non-ionic surfactants), and calcination temperatures and hold times (450–600 °C; 1–4 h) on the textural properties of MA were studied. Additionally, the targeted pore sizes of MA were obtained in the range of 3.1–5.4 nm by adjusting the surfactant and reaction time. The surface area and pore volume were controlledmore » by the calcination temperature and hold time while maintaining the thermal stability of the materials. The tuned MA of the large mesopore volume achieved 168 mg/g octamethylcyclotetrasiloxane (D4 siloxane) adsorption capacity, a 32% improvement compared to commercially activated alumina. Finally, after three adsorption recycles, the synthesized MA still maintained approximate 85% of its original adsorption capacity, demonstrating a sustainable adsorption performance and high potential for related industrial applications.« less

  11. Study of CO2 adsorption capacity of mesoporous carbon and activated carbon modified by triethylenetetramine (TETA)

    NASA Astrophysics Data System (ADS)

    Sulistianti, I.; Krisnandi, Y. K.; Moenandar, I.

    2017-04-01

    Mesoporous carbon was synthesized by soft template method using phloroglucinol and formaldehyde as a carbon source; and Pluronic F-127 as a mesoporous template. The synthesized mesoporous carbon and commercial activated carbon were modified with triethylenetetramine (TETA) to increase CO2 adsorption capacity. Based on FTIR characterization, the synthesized mesoporous carbon and the activated carbon without modification process has similarity pattern. After the modification, both of them showed absorption peaks in the area around 1580 to 1650 cm-1 which is known as N-H bending vibration and absorption peaks in the area around 3150 to 3380 cm-1 which is known as N-H stretching vibration. The XRD results showed two peaks at 2θ = 24.21° and 2θ = 43.85°, according to JCPDS index No. 75-1621 those peak are the typical peaks for hexagonal graphite carbon. In BET analysis, the synthesized mesoporous carbon and activated carbon modified TETA have surface area, pore volume and pore diameter lower than without modification process. In carbon dioxide adsorption testing, the synthesized mesoporous carbon showed better performance than the commercial activated carbon for CO2 adsorption both without modification and by modification. The synthesized mesoporous carbon obtained CO2 adsorption of 9.916 mmol/g and the activated carbon of 3.84 mmol/g for on 3.5 hours of adsorption. It is three times better than activated carbon for adsorption of carbon dioxide. The modified mesoporous carbon has the best performance for adsorption of gas CO2 if compared by unmodified.

  12. Enhancing the interaction strength and capacities of hydrogen storage via surface adsorption

    NASA Astrophysics Data System (ADS)

    Brown, Craig

    2008-03-01

    Storing Hydrogen molecules in porous media based on a physisorption mechanism is one possible approach to reach the US Department of Energy targets for on-board hydrogen storage. Although the storage capacities of metal-organic frameworks (MOFs) have progressed significantly over recent years, some technological obstacles pose challenges for their future improvement. These include the generally low H2 adsorption enthalpy limiting room temperature applications and the lack of understanding of surface packing density hindering the efficient improvement of H2 adsorption uptake. To improve the H2 affinity in MOFs, our previous work has shown that the coordinatively unsaturated metal centers (CUMCs) can greatly enhance the H2 binding strength. Our current study of MOF-74 will be presented, showing that its open Zn^2+ ions bind H2 strongly and are identified as being responsible for the large initial H2 adsorption enthalpy of 8.4 kJ/mol. In all, there are four H2 adsorption sites in MOF-74 identified by neutron powder diffraction. These four hydrogen adsorption sites are closely packed in MOF-74 and form a one dimensional nanoscale tube structure. We also demonstrate an interesting correlation that MOFs with CUMCs generally show larger surface packing densities than that of other MOFs without CUMCs. The implications of this will be addressed.

  13. Synthesis, fine structural characterization, and CO2 adsorption capacity of metal organic frameworks-74.

    PubMed

    Adhikari, Abhijit Krishna; Lin, Kuen-Song

    2014-04-01

    Two metal organic frameworks of MOF-74 group (zinc and copper-based) were successfully synthesized, characterized, and evaluated for CO2 adsorption. The both samples such as MOF-74(Zn) and MOF-74(Cu) were characterized with FE-SEM for morphology and particle size, XRD patterns for phase structure, FTIR for organic functional groups, nitrogen adsorption for pore textural properties, and X-ray absorption spectroscopy for fine structural parameters and oxidation states of central metal atoms. CO2 adsorption isotherms of MOF-74 samples were measured in a volumetric adsorption unit at 273 K and pressure up to 1.1 bar. The MOF-74(Zn) and MOF-74(Cu) adsorbents have the pore widths of 8.58 and 8.04 angstroms with the BET specific surface areas of 1,474 and 1,345 m2 g(-1), respectively. CO2 adsorption capacities of MOF-74(Zn) and MOF-74(Cu) were 4.10 and 3.38 mmol x g(-1), respectively measured at 273 K and 1.1 bar. The oxidation state of central atoms in MOF-74(Zn) was Zn(II) confirmed by XANES spectra while MOF-74(Cu) was composed of Cu(I) and Cu(II) central atoms. The bond distances of Zn--O and Cu--O were 1.98 and 1.94 angstroms, respectively.

  14. CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles exhibit fast and selective adsorption of arsenic with high adsorption capacity

    NASA Astrophysics Data System (ADS)

    Yang, Ji-Chun; Yin, Xue-Bo

    2017-01-01

    In this study, we report the synthesis and application of mesoporous CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles (MNPs) for the simultaneous removal of inorganic arsenic (iAs). The hybrid adsorbent had a core-shell and mesoporous structure with an average diameter of 260 nm. The nanoscale size and mesoporous character impart a fast adsorption rate and high adsorption capacity for iAs. In total, 0.1 mg L‑1 As(V) and As(III) could be adsorbed within 2 min, and the maximum adsorption capacities were 114.8 mg g‑1 for As(V) and 143.6 mg g‑1 for As(III), higher than most previously reported adsorbents. The anti-interference capacity for iAs adsorption was improved by the electrostatic repulsion and size exclusion effects of the MIL-100(Fe) shell, which also decreased the zero-charge point of the hybrid absorbent for a broad pH adsorption range. The adsorption mechanisms of iAs on the MNPs are proposed. An Fe-O-As structure was formed on CoFe2O4@MIL-100(Fe) through hydroxyl substitution with the deprotonated iAs species. Monolayer adsorption of As(V) was observed, while hydrogen bonding led to the multi-layer adsorption of neutral As(III) for its high adsorption capacity. The high efficiency and the excellent pH- and interference-tolerance capacities of CoFe2O4@MIL-100(Fe) allowed effective iAs removal from natural water samples, as validated with batch magnetic separation mode and a portable filtration strategy.

  15. CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles exhibit fast and selective adsorption of arsenic with high adsorption capacity

    PubMed Central

    Yang, Ji-Chun; Yin, Xue-Bo

    2017-01-01

    In this study, we report the synthesis and application of mesoporous CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles (MNPs) for the simultaneous removal of inorganic arsenic (iAs). The hybrid adsorbent had a core-shell and mesoporous structure with an average diameter of 260 nm. The nanoscale size and mesoporous character impart a fast adsorption rate and high adsorption capacity for iAs. In total, 0.1 mg L−1 As(V) and As(III) could be adsorbed within 2 min, and the maximum adsorption capacities were 114.8 mg g−1 for As(V) and 143.6 mg g−1 for As(III), higher than most previously reported adsorbents. The anti-interference capacity for iAs adsorption was improved by the electrostatic repulsion and size exclusion effects of the MIL-100(Fe) shell, which also decreased the zero-charge point of the hybrid absorbent for a broad pH adsorption range. The adsorption mechanisms of iAs on the MNPs are proposed. An Fe-O-As structure was formed on CoFe2O4@MIL-100(Fe) through hydroxyl substitution with the deprotonated iAs species. Monolayer adsorption of As(V) was observed, while hydrogen bonding led to the multi-layer adsorption of neutral As(III) for its high adsorption capacity. The high efficiency and the excellent pH- and interference-tolerance capacities of CoFe2O4@MIL-100(Fe) allowed effective iAs removal from natural water samples, as validated with batch magnetic separation mode and a portable filtration strategy. PMID:28102334

  16. Carboxylic acid functionalized sesame straw: A sustainable cost-effective bioadsorbent with superior dye adsorption capacity.

    PubMed

    Feng, Yanfang; Liu, Yang; Xue, Lihong; Sun, Haijun; Guo, Zhi; Zhang, Yingying; Yang, Linzhang

    2017-08-01

    This study prepared a carboxylic functionalized bioadsorbent that met the "4-E" criteria: Efficient, Economical, Environmentally friendly, and Easily-produced. Sesame straw (Sesamum indicum L.) was functionalized through treatment with citric acid (SSCA) and tartaric acid (SSTA). The products were examined for adsorption capacity and mechanisms. Langmuir model gave the best fit for the isotherm data, and the maximum monolayer adsorption capacity of SSCA was 650mgg(-1) for methylene blue (MB). The excellent dye adsorption capacity of SSCA can be attributed to the introduction of ester groups during citric-acid modification and the tube-like structures (i.e., sesame straw cell wall remnants). At last, the cost of carboxylic acid functionalized bioadsorbents was evaluated, which showed that SSCA would be the most cost-effective bioadsorbent. Additionally, this study presents a thermo-decomposition methodology for contaminant-loaded bioadsorbent. Results showed that SSCA is probably one of the few bioadsorbents that can be produced and applied in industrial scale. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. High adsorption capacity of V-doped TiO2 for decolorization of methylene blue

    NASA Astrophysics Data System (ADS)

    Nguyen, Thanh-Binh; Hwang, Moon-Jin; Ryu, Kwang-Sun

    2012-07-01

    In this study, pure TiO2 (V-TiO2-0) and V-doped TiO2 (V-TiO2-x, x = 1-10 mol%) were synthesized using a new sol-gel method. The adsorption capacity of the V-TiO2-x samples was evaluated by measuring the removal of methylene blue (MB) from aqueous solution via decolorization. Since the adsorption capacity was affected by the specific surface area, the interaction between adsorbate (MB) and adsorbent (V-TiO2-x), and the structure of the adsorbent, the physicochemical properties of the samples were investigated. Among the V-doped TiO2-x samples, the V-TiO2-10 sample showed the highest adsorption capacity, which was 11.36 times greater than that of pure TiO2, removing 85.2% of the MB after 2 h. Moreover, changing the molar ratio of the reactants in the V-TiO2-10 sample improved the performance of the material so that 91.6% of the MB was removed after 2 h.

  18. Adsorption of heavy metals on to sugar cane bagasse: improvement of adsorption capacities due to anaerobic degradation of the biosorbent.

    PubMed

    Joseph, Osnick; Rouez, Maxime; Métivier-Pignon, Hélène; Bayard, Rémy; Emmanuel, Evens; Gourdon, Rémy

    2009-12-01

    In this work, anaerobic degradation of sugar cane bagasse was studied with a dual objective: the production of biogas and the improvement of the material's characteristics for its implementation in adsorption processes. The biogas production was determined by means of biomethane potential tests carried out over two months of incubation at 35 degrees C. Biogas and methane cumulative productions were assumed to follow a first-order rate of decay. Theoretical cumulative methane and biogas productions were calculated using Buswell's equation. The anaerobic digestion resulted in a 92% decrease in the leachable organic fraction and a 40% mass loss of bagasse. The average productions of biogas and methane from the whole set of experiments were 293 +/- 6 and 122 +/- 4 mL g(-1) of volatile solids, respectively. The anaerobic incubation of the raw material led to an increase in adsorption capacities towards metal ions, which were multiplied by around 2.0 for Zn2+ and 2.3 for Cd2+.

  19. The effects of mariculture activities on the adsorption/desorption and chemical fractionations of mercury on sediments.

    PubMed

    Liang, Peng; Wu, Sheng-Chun; Li, Yi-Chun; Li, Hong-Bo; Yu, Guang-bin; Yu, Shen; Wong, Ming H

    2012-04-01

    The aims of the present study were to investigate the effects of mariculture activities on inorganic mercury (Hg(2+)) adsorption/desorption on sediments and the distributions of newly adsorbed Hg(2+) on different chemical fractionations. The adsorption amount and binding energy of Hg(2+) on mariculture sediment (MS) were significantly higher (p<0.05) than reference sediment (RS). This may be explained by the strong complexation role that exists between Hg(2+) and organic matter (OM), which derived from unconsumed fish feed and fish metabolites. The reducible Hg(2+) in MS was significantly lower (p<0.01) than RS, which may have been caused by the decreasing amount of iron and manganese hydroxide in MS, lead to the decrease of Hg(2+) bound to them. On the contrary, the residual Hg(2+) was significantly higher (p<0.01) in MS than RS, which suggests that newly adsorbed Hg(2+) was more stable in MS than RS.

  20. Complete Genome Sequence of a Marine Bacterium, Pseudomonas pseudoalcaligenes Strain S1, with High Mercury Resistance and Bioaccumulation Capacity

    PubMed Central

    Liu, Bing; Bian, Chao; Huang, Huiwei; Yin, Zhiwei

    2016-01-01

    Pseudomonas pseudoalcaligenes S1, a marine bacterium, exhibited strong resistance to a high concentration of Hg2+ and remarkable Hg2+ bioaccumulation capacity. Here, we report the 6.9-Mb genome sequence of P. pseudoalcaligenes S1, which may help clarify its phylogenetic status and provide further understanding of the mechanisms of mercury bioremediation in a marine environment. PMID:27198018

  1. MERCURY(II) ADSORPTION FROM WASTEWATERS USING A THIOL FUNCTIONAL ADSORBENT

    EPA Science Inventory

    The removal of mercury(II) from wastewaters (coal-fired utility plant scrubber solutions) using a thiol functional organoceramic composite (SOL-AD-IV) is investigated. A simulant is employed as a surrogate to demonstrate the removal of mercury from real waste solutions. Equilibri...

  2. MERCURY(II) ADSORPTION FROM WASTEWATERS USING A THIOL FUNCTIONAL ADSORBENT

    EPA Science Inventory

    The removal of mercury(II) from wastewaters (coal-fired utility plant scrubber solutions) using a thiol functional organoceramic composite (SOL-AD-IV) is investigated. A simulant is employed as a surrogate to demonstrate the removal of mercury from real waste solutions. Equilibri...

  3. High-capacity adsorption of dissolved hexavalent chromium using amine-functionalized magnetic corn stalk composites.

    PubMed

    Song, Wen; Gao, Baoyu; Zhang, Tengge; Xu, Xing; Huang, Xin; Yu, Huan; Yue, Qinyan

    2015-08-01

    Easily separable amine-functionalized magnetic corn stalk composites (AF-MCS) were employed for effective adsorption and reduction of toxic hexavalent chromium [Cr(VI)] to nontoxic Cr(III). The saturated magnetization of AF-MCS reached 6.2emu/g, and as a result, it could be separated from aqueous solution by a magnetic process for its superparamagnetism. The studies of various factors influencing the sorption behavior indicated that the optimum AF-MCS dosage for Cr(VI) adsorption was 1g/L, and the maximum adsorption capacity was observed at pH 3.0. The chromium adsorption perfectly fitted the Langmuir isotherm model and pseudo second order kinetic model. Furthermore, characterization of AF-MCS was investigated by means of XRD, SEM, TEM, FT-IR, BET, VSM and XPS analysis to discuss the uptake mechanism. Basically, these results demonstrated that AF-MCS prepared in this work has shown its merit in effective removal of Cr(VI) and rapid separation from effluents simultaneously.

  4. Design of 3D MnO2/Carbon sphere composite for the catalytic oxidation and adsorption of elemental mercury.

    PubMed

    Xu, Haomiao; Jia, Jinping; Guo, Yongfu; Qu, Zan; Liao, Yong; Xie, Jiangkun; Shangguan, Wenfeng; Yan, Naiqiang

    2017-08-08

    Three-dimensional (3D) MnO2/Carbon Sphere (MnO2/CS) composite was synthesized from zero-dimensional carbon spheres and one-dimensional α-MnO2 using hydrothermal method. The hierarchical MnO2/CS composite was applied for the catalytic oxidation and adsorption of elemental mercury (Hg(0)) from coal-fired flue gas. The characterization results indicated that this composite exhibits a 3D urchin morphology. Carbon spheres act as the core and α-MnO2 nano-rods grew on the surface of carbon spheres. This 3D hierarchical structure benefits the enlargement of surface areas and pore volumes. Hg(0) removal experimental results indicated that the MnO2/CS composite has an outstanding Hg(0) removal performance due to the higher catalytic oxidation and adsorption performance. MnO2/CS composite had higher than 99% Hg(0) removal efficiency even after 600min reaction. In addition, the nano-sized MnO2/CS composite exhibited better SO2 resistance than pure α-MnO2. Moreover, the Hg-TPD results indicated that the adsorbed mercury can release from the surface of MnO2/CS using a thermal decomposition method. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Unified method for the total pore volume and pore size distribution of hierarchical zeolites from argon adsorption and mercury intrusion.

    PubMed

    Kenvin, Jeffrey; Jagiello, Jacek; Mitchell, Sharon; Pérez-Ramírez, Javier

    2015-02-03

    A generalized approach to determine the complete distribution of macropores, mesopores, and micropores from argon adsorption and mercury porosimetry is developed and validated for advanced zeolite catalysts with hierarchically structured pore systems in powder and shaped forms. Rather than using a fragmented approach of simple overlays from individual techniques, a unified approach that utilizes a kernel constructed from model isotherms and model intrusion curves is used to calculate the complete pore size distribution and the total pore volume of the material. An added benefit of a single full-range pore size distribution is that the cumulative pore area and the area distribution are also obtained without the need for additional modeling. The resulting complete pore size distribution and the kernel accurately model both the adsorption isotherm and the mercury porosimetry. By bridging the data analysis of two primary characterization tools, this methodology fills an existing gap in the library of familiar methods for porosity assessment in the design of materials with multilevel porosity for novel technological applications.

  6. Intra- and inter-unit variation in fly ash petrography and mercury adsorption: Examples from a western Kentucky power station

    USGS Publications Warehouse

    Hower, J.C.; Finkelman, R.B.; Rathbone, R.F.; Goodman, J.

    2000-01-01

    Fly ash was collected from eight mechanical and 10 baghouse hoppers at each of the twin 150-MW wall-fired units in a western Kentucky power station. The fuel burned at that time was a blend of many low-sulfur, high-volatile bituminous Central Appalachian coals. The baghouse ash showed less variation between units than the mechanical hoppers. The mechanical fly ash, coarser than the baghouse ash, showed significant differences in the amount of total carbon and in the ratio of isotropic coke to both total carbon and total coke - the latter excluding inertinite and other unburned, uncoked coal. There was no significant variation in proportions of inorganic fly ash constituents. The inter-unit differences in the amount and forms of mechanical fly ash carbon appear to be related to differences in pulverizer efficiency, leading to greater amounts of coarse coal, therefore unburned carbon, in one of the units. Mercury capture is a function of both the total carbon content and the gas temperature at the point of fly ash separation, mercury content increasing with an increase in carbon for a specific collection system. Mercury adsorption on fly ash carbon increases at lower flue-gas temperatures. Baghouse fly ash, collected at a lower temperature than the higher-carbon mechanically separated fly ash, contains a significantly greater amount of Hg.

  7. Construction of horizontal stratum landform-like composite foams and their methyl orange adsorption capacity

    NASA Astrophysics Data System (ADS)

    Chen, Jiajia; Shi, Xiaowen; Zhan, Yingfei; Qiu, Xiaodan; Du, Yumin; Deng, Hongbing

    2017-03-01

    Chitosan (CS)/rectorite (REC)/carbon nanotubes (CNTs) composite foams with good mechanical properties were successfully fabricated by unidirectional freeze-casting technique. The morphology of the foam showed the well-ordered porous three-dimensional layers and horizontal stratum landform-like structure. The holes on the layers looked like the wings of butterfly. Additionally, the X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy results indicated the successful addition of CNTs and REC. The intercalated REC with CS chains was confirmed by small-angle X-ray diffraction. The surface structure of the foams was also analyzed by Raman spectroscopy. The adsorption experiments showed that when the mass ratio of CS to REC was 10:1 and CNTs content was 20%, the composite foam performed best in adsorbing low concentration methyl orange, and the largest adsorption capacity was 41.65 mg/g.

  8. Porous carbon with small mesoporesas an ultra-high capacity adsorption medium

    NASA Astrophysics Data System (ADS)

    Gao, Biaofeng; Zhou, Haitao; Chen, De; Yang, Jianhong

    2017-10-01

    Resins (732-type), abundant and inexpensive resources were used to prepare porous carbon with small mesopores (CSM) by carbonization and post-chemical-activation with potassium hydroxide (KOH). The N2 adsorption measurements revealed that CSM had high surface areas (1776.5 m2 g-1), large pore volumes (1.10 cm3 g-1), and nearly optimal narrow small mesopore sizes ranging from 2 to 7 nm. CSM was used as adsorbent to investigate the adsorption behavior for Rhodamine B (RhB). Due to the optimal pore size distributions (PSD), intensive-stacking interaction, S-doped, and electrostatic attraction, the CSM exhibited an ultra-high-capacity of 1590 mg g-1 for RhB in aqueous solutions.

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

    USGS Publications Warehouse

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

    2017-01-01

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

  10. A Valuable Biochar from Poplar Catkins with High Adsorption Capacity for Both Organic Pollutants and Inorganic Heavy Metal Ions.

    PubMed

    Liu, Xia; Sun, Ju; Duan, Shengxia; Wang, Yanan; Hayat, Tasawar; Alsaedi, Ahmed; Wang, Chengming; Li, Jiaxing

    2017-08-30

    In this paper, biochar derived from poplar catkins was used as an economical and renewable adsorbent for adsorption organic and inorganic pollutants such as, dyes, organic compounds, and heavy metal ions from wastewater. Mesoporous activated carbonized poplar catkins (ACPCs) were produced from char as a by-product by carbonized poplar catkins (CPCs). With their high surface area, ACPCs exhibited the maximum adsorption capacities of 71.85 and 110.17 mg/g for the removal of inorganic U(VI) and Co(II). Compared other biochars adsorbents, ACPCs can also adsorb organic pollutants with the maximum adsorption capacities of 534, 154, 350, 148 and 384 mg/g for methylene blue (MB), methyl orange (MO), Congo red (CR), chloramphenicol (CAP) and naphthalene. The adsorption of organic pollutants was fitted with pseudo-first order, pseudo-second order, and intra-particle diffusion kinetic models figure out the kinetic parameters and adsorption mechanisms. Langmuir adsorption isotherm was found to be suitable for Co(II) and U(VI) adsorption and thermodynamic studies indicated adsorption processes to be endothermic and spontaneous. The adsorption process includes both outer-sphere surface complexes and hydrogen-bonding interactions. The results showed that biochar derived from poplar catkins was a potential material to remove pollutants in wastewater.

  11. A review on modification methods to cellulose-based adsorbents to improve adsorption capacity.

    PubMed

    Hokkanen, Sanna; Bhatnagar, Amit; Sillanpää, Mika

    2016-03-15

    In recent decades, increased domestic, agricultural and industrial activities worldwide have led to the release of various pollutants, such as toxic heavy metals, inorganic anions, organics, micropollutants and nutrients into the aquatic environment. The removal of these wide varieties of pollutants for better quality of water for various activities is an emerging issue and a robust and eco-friendly treatment technology is needed for the purpose. It is well known that cellulosic materials can be obtained from various natural sources and can be employed as cheap adsorbents. Their adsorption capacities for heavy metal ions and other aquatic pollutants can be significantly affected upon chemical treatment. In general, chemically modified cellulose exhibits higher adsorption capacities for various aquatic pollutants than their unmodified forms. Numerous chemicals have been used for cellulose modifications which include mineral and organic acids, bases, oxidizing agent, organic compounds, etc. This paper reviews the current state of research on the use of cellulose, a naturally occurring material, its modified forms and their efficacy as adsorbents for the removal of various pollutants from waste streams. In this review, an extensive list of various cellulose-based adsorbents from literature has been compiled and their adsorption capacities under various conditions for the removal of various pollutants, as available in the literature, are presented along with highlighting and discussing the key advancement on the preparation of cellulose-based adsorbents. It is evident from the literature survey presented herein that modified cellulose-based adsorbents exhibit good potential for the removal of various aquatic pollutants. However, still there is a need to find out the practical utility of these adsorbents on a commercial scale, leading to the improvement of pollution control.

  12. Trimodal nanoporous silica as a support for amine-based CO2 adsorbents: Improvement in adsorption capacity and kinetics

    NASA Astrophysics Data System (ADS)

    Chen, Chao; Bhattacharjee, Samiran

    2017-02-01

    A trimodal nanoporous silica (TS) having unique trimodal pore structure viz., internal mesopores, textural mesopores and interconnected macropores, has been functionalized with amine using two different methods covalent grafting and wet impregnation. Both were studied as nanocomposite sorbents for CO2 capture. The effects of the amine loading, immobilization processes and the type of support were investigated. Commercially available silica gel (SG) with a purely mesoporous structure was studied as the support for the amine in order to compare differences in pore structure and amine loading with differences in CO2 adsorption capacity and kinetics. Amine-grafted TS exhibited much faster CO2 adsorption kinetics at 35 °C than amine-grafted SG. At the same amine loading, amine-impregnated TS showed higher CO2 adsorption capacity and faster CO2 adsorption kinetics than amine-impregnated SG. The CO2 adsorption capacity of amine-impregnated TS increased as the amine loading increased until 70%, with the highest value of 172 mg/g, while the amine-impregnated SG reached the highest CO2 adsorption capacity of only 78 mg/g at 40% amine loading. More importantly, amine-impregnated as-prepared TS exhibited even higher CO2 capture capacity than amine-impregnated TS when the amine loading was below 60%. Results suggest that amine-modified trimodal nanoporous silica sorbents meet the challenges of current CO2 capture technology.

  13. Adsorption capacities of activated carbons for geosmin and 2-methylisoborneol vary with activated carbon particle size: Effects of adsorbent and adsorbate characteristics.

    PubMed

    Matsui, Yoshihiko; Nakao, Soichi; Sakamoto, Asuka; Taniguchi, Takuma; Pan, Long; Matsushita, Taku; Shirasaki, Nobutaka

    2015-11-15

    The adsorption capacities of nine activated carbons for geosmin and 2-methylisoborneol (MIB) were evaluated. For some carbons, adsorption capacity substantially increased when carbon particle diameter was decreased from a few tens of micrometers to a few micrometers, whereas for other carbons, the increase of adsorption capacity was small for MIB and moderate for geosmin. An increase of adsorption capacity was observed for other hydrophobic adsorbates besides geosmin and MIB, but not for hydrophilic adsorbates. The parameter values of a shell adsorption model describing the increase of adsorption capacity were negatively correlated with the oxygen content of the carbon among other characteristics. Low oxygen content indicated low hydrophilicity. The increase of adsorption capacity was related to the hydrophobic properties of both adsorbates and activated carbons. For adsorptive removal of hydrophobic micropollutants such as geosmin, it is therefore recommended that less-hydrophilic activated carbons, such as coconut-shell-based carbons, be microground to a particle diameter of a few micrometers to enhance their equilibrium adsorption capacity. In contrast, adsorption by hydrophilic carbons or adsorption of hydrophilic adsorbates occur in the inner pores, and therefore adsorption capacity is unchanged by particle size reduction.

  14. Mercury

    NASA Technical Reports Server (NTRS)

    Gault, D. E.; Burns, J. A.; Cassen, P.; Strom, R. G.

    1977-01-01

    Prior to the flight of the Mariner 10 spacecraft, Mercury was the least investigated and most poorly known terrestrial planet (Kuiper 1970, Devine 1972). Observational difficulties caused by its proximity to the Sun as viewed from Earth caused the planet to remain a small, vague disk exhibiting little surface contrast or details, an object for which only three major facts were known: 1. its bulk density is similar to that of Venus and Earth, much greater than that of Mars and the Moon; 2. its surface reflects electromagnetic radiation at all wavelengths in the same manner as the Moon (taking into account differences in their solar distances); and 3. its rotation period is in 2/3 resonance with its orbital period. Images obtained during the flyby by Mariner 10 on 29 March 1974 (and the two subsequent flybys on 21 September 1974 and 16 March 1975) revealed Mercury's surface in detail equivalent to that available for the Moon during the early 1960's from Earth-based telescopic views. Additionally, however, information was obtained on the planet's mass and size, atmospheric composition and density, charged-particle environment, and infrared thermal radiation from the surface, and most significantly of all, the existence of a planetary magnetic field that is probably intrinsic to Mercury was established. In the following, this new information is summarized together with results from theoretical studies and ground-based observations. In the quantum jumps of knowledge that have been characteristic of "space-age" exploration, the previously obscure body of Mercury has suddenly come into sharp focus. It is very likely a differentiated body, probably contains a large Earth-like iron-rich core, and displays a surface remarkably similar to that of the Moon, which suggests a similar evolutionary history.

  15. Volumetric interpretation of protein adsorption: capacity scaling with adsorbate molecular weight and adsorbent surface energy.

    PubMed

    Parhi, Purnendu; Golas, Avantika; Barnthip, Naris; Noh, Hyeran; Vogler, Erwin A

    2009-12-01

    Silanized-glass-particle adsorbent capacities are extracted from adsorption isotherms of human serum albumin (HSA, 66 kDa), immunoglobulin G (IgG, 160 kDa), fibrinogen (Fib, 341 kDa), and immunoglobulin M (IgM, 1000 kDa) for adsorbent surface energies sampling the observable range of water wettability. Adsorbent capacity expressed as either mass-or-moles per-unit-adsorbent-area increases with protein molecular weight (MW) in a manner that is quantitatively inconsistent with the idea that proteins adsorb as a monolayer at the solution-material interface in any physically-realizable configuration or state of denaturation. Capacity decreases monotonically with increasing adsorbent hydrophilicity to the limit-of-detection (LOD) near tau(o) = 30 dyne/cm (theta approximately 65 degrees) for all protein/surface combinations studied (where tau(o) identical with gamma(lv)(o) costheta is the water adhesion tension, gamma(lv)(o) is the interfacial tension of pure-buffer solution, and theta is the buffer advancing contact angle). Experimental evidence thus shows that adsorbent capacity depends on both adsorbent surface energy and adsorbate size. Comparison of theory to experiment implies that proteins do not adsorb onto a two-dimensional (2D) interfacial plane as frequently depicted in the literature but rather partition from solution into a three-dimensional (3D) interphase region that separates the physical surface from bulk solution. This interphase has a finite volume related to the dimensions of hydrated protein in the adsorbed state (defining "layer" thickness). The interphase can be comprised of a number of adsorbed-protein layers depending on the solution concentration in which adsorbent is immersed, molecular volume of the adsorbing protein (proportional to MW), and adsorbent hydrophilicity. Multilayer adsorption accounts for adsorbent capacity over-and-above monolayer and is inconsistent with the idea that protein adsorbs to surfaces primarily through protein

  16. Volumetric Interpretation of Protein Adsorption: Capacity Scaling with Adsorbate Molecular Weight and Adsorbent Surface Energy

    PubMed Central

    Parhi, Purnendu; Golas, Avantika; Barnthip, Naris; Noh, Hyeran; Vogler, Erwin A.

    2009-01-01

    Silanized-glass-particle adsorbent capacities are extracted from adsorption isotherms of human serum albumin (HSA, 66 kDa), immunoglobulin G (IgG, 160 kDa), fibrinogen (Fib, 341 kDa), and immunoglobulin M (IgM, 1000 kDa) for adsorbent surface energies sampling the observable range of water wettability. Adsorbent capacity expressed as either mass-or-moles per-unit-adsorbent-area increases with protein molecular weight (MW) in a manner that is quantitatively inconsistent with the idea that proteins adsorb as a monolayer at the solution-material interface in any physically-realizable configuration or state of denaturation. Capacity decreases monotonically with increasing adsorbent hydrophilicity to the limit-of-detection (LOD) near τo = 30 dyne/cm (θ~65o) for all protein/surface combinations studied (where τo≡γlvocosθ is the water adhesion tension, γlvo is the interfacial tension of pure-buffer solution, and θ is the buffer advancing contact angle). Experimental evidence thus shows that adsorbent capacity depends on both adsorbent surface energy and adsorbate size. Comparison of theory to experiment implies that proteins do not adsorb onto a two-dimensional (2D) interfacial plane as frequently depicted in the literature but rather partition from solution into a three-dimensional (3D) interphase region that separates the physical surface from bulk solution. This interphase has a finite volume related to the dimensions of hydrated protein in the adsorbed state (defining “layer” thickness). The interphase can be comprised of a number of adsorbed-protein layers depending on the solution concentration in which adsorbent is immersed, molecular volume of the adsorbing protein (proportional to MW), and adsorbent hydrophilicity. Multilayer adsorption accounts for adsorbent capacity over-and-above monolayer and is inconsistent with the idea that protein adsorbs to surfaces primarily through protein/surface interactions because proteins within second (or higher

  17. Elemental mercury adsorption on sulfur-impregnated porous carbon - a review.

    PubMed

    Reddy, K Suresh Kumar; Shoaibi, Ahmed Al; Srinivasakannan, C

    2014-01-01

    The presence of elemental mercury in wellhead natural gas is an important industrial problem, since even low levels of mercury can damage cryogenic aluminium heat exchangers and other plant equipment. Mercury present in the natural gas stream will also dramatically shorten the useful life of precious metal catalysts. The present work reviews the overall process of elemental mercury removal in practice using non-regenerative adsorbents (e.g. sulfur-impregnated porous carbon), addressing the various influencing parameters such as the method of sulfur impregnation, the impregnation temperature, the sulfur to carbon ratio, the impregnation time, the impact of flue gas constituents, the effect of processing temperature, and the nature of any carbon-containing functional groups present. The distribution of elemental sulfur is found to be the key to developing an effective adsorbent, rather than quantity of sulfur impregnated. Modifying or developing an adsorbent for elemental mercury removal from natural gas needs a detail physical and chemical characteristics assessment of the adsorbent.

  18. An adsorbent with a high adsorption capacity obtained from the cellulose sludge of industrial residues.

    PubMed

    Orlandi, Géssica; Cavasotto, Jéssica; Machado, Francisco R S; Colpani, Gustavo L; Magro, Jacir Dal; Dalcanton, Francieli; Mello, Josiane M M; Fiori, Márcio A

    2017-02-01

    One of the major problems in effluent treatment plants of the cellulose and paper industry is the large amount of residual sludge generated. Therefore, this industry is trying to develop new methods to treat such residues and to use them as new products, such as adsorbents. In this regard, the objective of this work was to develop an adsorbent using the raw activated sludge generated by the cellulose and paper industry. The activated cellulose sludge, after being dried, was chemically activated with 42.5% (v/v) phosphoric acid at 85 °C for 1 h and was charred at 500 °C, 600 °C and 700 °C for 2 h. The efficiency of the obtained adsorbent materials was evaluated using kinetic tests with methylene blue solutions. Using the adsorption kinetics, it was verified that the three adsorbents showed the capacity to adsorb dye, and the adsorbent obtained at a temperature of 600 °C showed the highest adsorption capacity of 107.1 mg g(-1). The kinetic model that best fit the experimental data was pseudo-second order. The Langmuir-Freudlich isotherm adequately described the experimental data. As a result, the cellulose sludge generated by the cellulose and paper industries could be used as an adsorbent.

  19. Ultra-high adsorption capacity of zeolitic imidazole framework-67 (ZIF-67) for removal of malachite green from water.

    PubMed

    Lin, Kun-Yi Andrew; Chang, Hsuan-Ang

    2015-11-01

    Zeolitic imidazole frameworks (ZIFs), a new class of adsorbents, are proposed to adsorb Malachite Green (MG) in water. Particularly, ZIF-67 was selected owing to its stability in water and straightforward synthesis. The as-synthesized ZIF-67 was characterized and used to adsorb MG from water. Factors affecting the adsorption capacity were investigated including mixing time, temperature, the presence of salts and pH. The kinetics, adsorption isotherm and thermodynamics of the MG adsorption to ZIF-67 were also studied. The adsorption capacity of ZIF-67 for MG could be as high as 2430mgg(-1) at 20°C, which could be improved at the higher temperatures. Such an ultra-high adsorption capacity of ZIF-67 was almost 10-times of those of conventional adsorbents, including activated carbons and biopolymers. A mechanism for the high adsorption capacity was proposed and possibly attributed to the π-π stacking interaction between MG and ZIF-67. ZIF-67 also could be conveniently regenerated by washing with ethanol and the regeneration efficiency could remain 95% up to 4 cycles of the regeneration. ZIF-67 was also able to remove MG from the aquaculture wastewater, in which MG can be typically found. These features enable ZIF-67 to be one of the most effective and promising adsorbent to remove MG from water.

  20. Influence of Environmental Factors on the Adsorption Capacity and Thermal Conductivity of Silica Nano-Porous Materials.

    PubMed

    Zhang, Hu; Gu, Wei; Li, Ming-Jia; Fang, Wen-Zhen; Li, Zeng-Yao; Tao, Wen-Quan

    2015-04-01

    In this work, the influence of temperature and humidity environment on the water vapor adsorption capacity and effective thermal conductivity of silica nano-porous material is conducted within a relative humidity range from 15% to 90% at 25 °C, 40 °C and 55 °C, respectively. The experiment results show that both the temperature and relative humidity have significant influence on the adsorption capacity and effective thermal conductivity of silica nano-porous materials. The adsorption capacity and effective thermal conductivity increase with humidity because of the increases of water vapor concentration. The effective thermal conductivity increases linearly with adsorption saturation capacity at constant temperature. Because adsorption process is exothermic reaction, the increasing temperature is not conducive to the adsorption. But the effective thermal conductivity increases with the increment of temperature at the same water uptake because of the increment of water thermal conductivity with temperature Geometric models and unit cell structure are adopted to predict the effective thermal conductivity and comparisons with the experimental result are made, and for the case of moist silica nano-porous materials with high porosity no quantitative agreement is found. It is believed that the adsorbed water will fill in the nano-pores and gap and form lots of short cuts, leading to a significant reduction of the thermal resistance.

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

    PubMed

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

    2017-02-01

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

  2. Study on the Adsorption Capacities for Airborne Particulates of Landscape Plants in Different Polluted Regions in Beijing (China).

    PubMed

    Zhang, Wei-Kang; Wang, Bing; Niu, Xiang

    2015-08-14

    Urban landscape plants are an important component of the urban ecosystem, playing a significant role in the adsorption of airborne particulates and air purification. In this study, six common landscape plants in Beijing were chosen as research subjects, and the adsorption capacities for each different plant leaf and the effects of the leaf structures for the adsorption capacities for particulates were determined. Preliminary results show that needle-leaved tree species adsorbed more airborne particulates than broad-leaved tree species for the same leaf area. Pinus tabuliformis exhibits the highest adsorption capacity, at 3.89 ± 0.026 μg·cm(-2), almost two times as much as that of Populus tomentosa (2.00 ± 0.118 μg·cm(-2)). The adsorption capacities for PM10 of the same tree species leaves, in different polluted regions had significant differences, and the adsorption capacities for PM10 of the tree species leaf beside the Fifth Ring Road were higher than those of the tree species leaves in the Botanical Garden, although the adsorption capacities for PM2.5 of the same tree species in different polluted regions had no significant differences. By determining the soluble ion concentrations of the airborne particulates in two regions, it is suggested that the soluble ion concentrations of PM10 in the atmosphere in the Botanical Garden and beside the Fifth Ring Road have significant differences, while those of PM2.5 in the atmosphere had no significant differences. In different polluted regions there are significant adaptive changes to the leaf structures, and when compared with slightly polluted region, in the seriously polluted region the epidermis cells of the plant leaves shrinked, the surface textures of the leaves became rougher, and the stomas' frequency and the pubescence length increased. Even though the plant leaves exposed to the seriously polluted region changed significantly, these plants can still grow normally and healthily.

  3. Study on the Adsorption Capacities for Airborne Particulates of Landscape Plants in Different Polluted Regions in Beijing (China)

    PubMed Central

    Zhang, Wei-Kang; Wang, Bing; Niu, Xiang

    2015-01-01

    Urban landscape plants are an important component of the urban ecosystem, playing a significant role in the adsorption of airborne particulates and air purification. In this study, six common landscape plants in Beijing were chosen as research subjects, and the adsorption capacities for each different plant leaf and the effects of the leaf structures for the adsorption capacities for particulates were determined. Preliminary results show that needle-leaved tree species adsorbed more airborne particulates than broad-leaved tree species for the same leaf area. Pinus tabuliformis exhibits the highest adsorption capacity, at 3.89 ± 0.026 μg·cm−2, almost two times as much as that of Populus tomentosa (2.00 ± 0.118 μg·cm−2). The adsorption capacities for PM10 of the same tree species leaves, in different polluted regions had significant differences, and the adsorption capacities for PM10 of the tree species leaf beside the Fifth Ring Road were higher than those of the tree species leaves in the Botanical Garden, although the adsorption capacities for PM2.5 of the same tree species in different polluted regions had no significant differences. By determining the soluble ion concentrations of the airborne particulates in two regions, it is suggested that the soluble ion concentrations of PM10 in the atmosphere in the Botanical Garden and beside the Fifth Ring Road have significant differences, while those of PM2.5 in the atmosphere had no significant differences. In different polluted regions there are significant adaptive changes to the leaf structures, and when compared with slightly polluted region, in the seriously polluted region the epidermis cells of the plant leaves shrinked, the surface textures of the leaves became rougher, and the stomas’ frequency and the pubescence length increased. Even though the plant leaves exposed to the seriously polluted region changed significantly, these plants can still grow normally and healthily. PMID:26287227

  4. The adsorption behavior of mercury on the hematite (1-102) surface from coal-fired power plant emissions

    NASA Astrophysics Data System (ADS)

    Jung, J. E.; Jew, A. D.; Rupp, E.; Aboud, S.; Brown, G. E.; Wilcox, J.

    2014-12-01

    One of the biggest environmental concerns caused by coal-fired power plants is the emission of mercury (Hg). Worldwide, 475 tons of Hg are released from coal-burning processes annually, comprising 24% of total anthropogenic Hg emissions. Because of the high toxicity of Hg species, US Environmental Protection Agency (EPA) proposed a standard on Hg and air toxic pollutants (Mercury and Air Toxics Standards, MATS) for new and existing coal-fired power plants in order to eliminate Hg in flue gas prior to release through the stack. To control the emission of Hg from coal-derived flue gas, it is important to understand the behavior, speciation of Hg as well as the interaction between Hg and solid materials, such as fly ash or metal oxides, in the flue gas stream. In this study, theoretical investigations using density functional theory (DFT) were carried out in conjunction with experiments to investigate the adsorption behavior of oxidized Hg on hematite (α-Fe2O3), an important mineral component of fly ash which readily sorbes Hg from flue gas. For DFT calculation, the two α-Fe2O3 (1-102) surfaces modeled consisted of two different surface terminations: (1) M2-clean, which corresponds to the oxygen-terminated surface with the first layer of cations removed and with no hydroxyl groups and (2) M2-OH2-OH, which has bihydroxylated top oxygen atoms and a second layer of hydroxylated oxygen atoms. These surface terminations were selected because both surfaces are highly stable in the temperature range of flue gases. The most probable adsorption sites of Hg, Cl and HgCl on the two α-Fe2O3 surface terminations were suggested based on calculated adsorption energies. Additionally, Bader charge and projected density of states (PDOS) analyses were conducted to characterize the oxidation state of adsorbates and their bonding interactions with the surfaces. Results indicate that oxidized Hg physically adsorbs on the M2-clean surface with a binding energy of -0.103 eV and that

  5. Hydrophobic interaction chromatography of proteins. IV. Protein adsorption capacity and transport in preparative mode.

    PubMed

    To, Brian C S; Lenhoff, Abraham M

    2011-01-21

    The adsorption isotherms of four model proteins (lysozyme, α-lactalbumin, ovalbumin, and BSA) on eight commercial phenyl hydrophobic interaction chromatography media were measured. The isotherms were softer than those usually seen in ion-exchange chromatography of proteins, and the static capacities of the media were lower, ranging from 30 to 110 mg/mL, depending on the ammonium sulfate concentration and the protein and adsorbent types. The protein-accessible surface area appears to be the main factor determining the binding capacity, and little correlation was seen with the protein affinities of the adsorbents. Breakthrough experiments showed that the dynamic capacities of the adsorbents at 10% breakthrough were 20-80% of the static capacities, depending on adsorbent type. Protein diffusivities in the adsorbents were estimated from batch uptake experiments using the pore diffusion and homogeneous diffusion models. Protein transport was affected by the adsorbent pore structures. Apparent diffusivities were higher at lower salt concentrations and column loadings, suggesting that adsorbed proteins may retard intraparticle protein transport. The diffusivities estimated from the batch uptake experiments were used to predict column breakthrough behavior. Analytical solutions developed for ion-exchange systems were able to provide accurate predictions for lysozyme breakthrough but not for ovalbumin. Impurities in the ovalbumin solutions used for the breakthrough experiments may have affected the ovalbumin uptake and led to the discrepancies between the predictions and the experimental results.

  6. Investigation of adsorption behavior of mercury on Au(111) from first principles.

    PubMed

    Lim, Dong-Hee; Aboud, Shela; Wilcox, Jennifer

    2012-07-03

    The structural and electronic properties of Hg, SO(2), HgS, and HgO adsorption on Au(111) surfaces have been determined using density functional theory with the generalized gradient approximation. The adsorption strength of Hg on Au(111) increases by a factor of 1.3 (from -9.7 to -12.6 kcal/mol) when the number of surface vacancies increases from 0 to 3; however, the adsorption energy decreases with more than three vacancies. In the case of SO(2) adsorption on Au(111), the Au surface atoms are better able to stabilize the SO(2) molecule when they are highly undercoordinated. The SO(2) adsorption stability is enhanced from -0.8 to -9.3 kcal/mol by increasing the number of vacancies from 0 to 14, with the lowest adsorption energy of -10.2 kcal/mol at 8 Au vacancies. Atomic sulfur and oxygen precovered-Au(111) surfaces lower the Hg stability when Hg adsorbs on the top of S and O atoms. However, a cooperative effect between adjacent Hg atoms is observed as the number of S and Hg atoms increases on the perfect Au(111) surface, resulting in an increase in the magnitude of Hg adsorption. Details of the electronic structure properties of the Hg-Au systems are also discussed.

  7. Mercury Adsorption and Oxidation over Cobalt Oxide Loaded Magnetospheres Catalyst from Fly Ash in Oxyfuel Combustion Flue Gas.

    PubMed

    Yang, Jianping; Zhao, Yongchun; Chang, Lin; Zhang, Junying; Zheng, Chuguang

    2015-07-07

    Cobalt oxide loaded magnetospheres catalyst from fly ash (Co-MF catalyst) showed good mercury removal capacity and recyclability under air combustion flue gas in our previous study. In this work, the Hg(0) removal behaviors as well as the involved reactions mechanism were investigated in oxyfuel combustion conditions. Further, the recyclability of Co-MF catalyst in oxyfuel combustion atmosphere was also evaluated. The results showed that the Hg(0) removal efficiency in oxyfuel combustion conditions was relative high compared to that in air combustion conditions. The presence of enriched CO2 (70%) in oxyfuel combustion atmosphere assisted the mercury oxidation due to the oxidation of function group of C-O formed from CO2. Under both atmospheres, the mercury removal efficiency decreased with the addition of SO2, NO, and H2O. However, the enriched CO2 in oxyfuel combustion atmosphere could somewhat weaken the inhibition of SO2, NO, and H2O. The multiple capture-regeneration cycles demonstrated that the Co-MF catalyst also present good regeneration performance in oxyfuel combustion atmosphere.

  8. Synthesis and application of hydride silica composites for rapid and facile removal of aqueous mercury.

    PubMed

    Katok, Kseniia V; Whitby, Raymond L D; Fayon, Franck; Bonnamy, Sylvie; Mikhalovsky, Sergey V; Cundy, Andrew B

    2013-12-16

    The adsorption of ionic mercury(II) from aqueous solution on functionalized hydride silicon materials was investigated. The adsorbents were prepared by modification of mesoporous silica C-120 with triethoxysilane or by converting alkoxysilane into siloxanes by reaction with acetic acid. Mercury adsorption isotherms at 208C are reported, and maximum mercury loadings were determined by Langmuir fitting. Adsorbents exhibited efficient and rapid removal of ionic mercury from aqueous solution, with a maximum mercury loading of approximately 0.22 and 0.43 mmol of Hg g1 of silica C-120 and polyhedraloligomeric silsesquioxane (POSS) xerogel, respectively. Adsorption efficiency remained almost constant from pH 2.7 to 7. These inexpensive adsorbents exhibiting rapid assembly, low pH sensitivity, and high reactivity and capacity, are potential candidates as effective materials for mercury decontamination in natural waters and industrial effluents.

  9. Reservoir capacity estimates in shale plays based on experimental adsorption data

    NASA Astrophysics Data System (ADS)

    Ngo, Tan

    from different measurement techniques using representative fluids (such as CH4 and CO2) at elevated pressures, and the adsorbed density can range anywhere between the liquid and the solid state of the adsorbate. Whether these discrepancies are associated with the inherent heterogeneity of mudrocks and/or with poor data quality requires more experiments under well-controlled conditions. Nevertheless, it has been found in this study that methane GIP estimates can vary between 10-45% and 10-30%, respectively, depending on whether the free or the total amount of gas is considered. Accordingly, CO2 storage estimates range between 30-90% and 15-50%, due to the larger adsorption capacity and gas density at similar pressure and temperature conditions. A manometric system has been designed and built that allows measuring the adsorption of supercritical fluids in microporous materials. Preliminary adsorption tests have been performed using a microporous 13X zeolite and CO 2 as an adsorbing gas at a temperature of 25oC and 35oC and at pressures up to 500 psi. Under these conditions, adsorption is quantified with a precision of +/- 3%. However, relative differences up to 15-20% have been observed with respect to data published in the literature on the same adsorbent and at similar experimental conditions. While it cannot be fully explained with uncertainty analysis, this discrepancy can be reduced by improving experiment practice, thus including the application of a higher adsorbent's regeneration temperature, of longer equilibrium times and of a careful flushing of the system between the various experimental steps. Based on the results on 13X zeolite, virtual tests have been conducted to predict the performance of the manometric system to measure adsorption on less adsorbing materials, such as mudrocks. The results show that uncertainties in the estimated adsorbed amount are much more significant in shale material and they increase with increasing pressure. In fact, relative

  10. Adsorption capacities of poly-γ-glutamic acid and its sodium salt for cesium removal from radioactive wastewaters.

    PubMed

    Sakamoto, Shigeki; Kawase, Yoshinori

    2016-12-01

    Cesium removal from radioactive wastewaters was examined using water-insoluble poly-γ-glutamic acid (γ-PGA) and water-soluble sodium salt form poly-γ-L-glutamic acid (γ-PGANa) as biosorbents. The maximum adsorption capacities at equilibrium of γ-PGA and γ-PGANa for Cs were 345 mg-Cs(g-γ-PGA)(-1) at pH 6.0 and 290 mg-Cs(g-γ-PGANa)(-1) at pH 9.0, respectively. At lower pH < pKa, the carboxyl groups of γ-PGA primarily remained in the protonated form and adsorption of Cs only slightly occurred. At higher pH > pKa, the adsorption of Cs was significantly facilitated due to ionization of carboxyl groups to carboxylate ion. Adsorption of Cs at pH > 9.0 was inhibited due to the hydrolysis of Cs. The Langmuir model could successfully describe the isotherm data. For γ-PGA and γ-PGANa, the maximum adsorption capacities at equilibrium in the Langmuir model were 446 and 333 mg-Cs(g-adsorbent)(-1), respectively. The high adsorption capacities confirmed a potential utilization of γ-PGA and γ-PGANa for Cs removal. The adsorption of Cs by both γ-PGA and γ-PGANa attained the equilibrium within 0.5 min. The very quick equilibration is a benefit from the viewpoint of practical application. The spectra of FT-IR and XPS before and after adsorption confirmed the adsorption of Cs onto γ-PGA and γ-PGANa via electrostatic interaction with carboxylate anions.

  11. In-Situ Ligand Formation-Driven Preparation of a Heterometallic Metal-Organic Framework for Highly Selective Separation of Light Hydrocarbons and Efficient Mercury Adsorption.

    PubMed

    Han, Yi; Zheng, Hao; Liu, Kang; Wang, Hongli; Huang, Hongliang; Xie, Lin-Hua; Wang, Lei; Li, Jian-Rong

    2016-09-07

    By means of the in situ ligand formation strategy and hard-soft acid-base (HSAB) theory, two types of independent In(COO)4 and Cu6S6 clusters were rationally embedded into the heterometallic metal-organic framework (HMOF) {[(CH3)2NH2]InCu4L4·xS}n (BUT-52). BUT-52 exhibits a three-dimensional (3D) anionic framework structure and has sulfur decorating the dumbbell-shaped cages with the external edges of 24 and 14 Å by the internal edges. Remarkably, because of the stronger charge-induced interactions between the charged MOF skeleton and the easily polarized C2 hydrocarbons (C2s), BUT-52 was used for C2s over CH4 and shows both high adsorption heats of C2s and selective separation abilities for C2s/CH4. Furthermore, BUT-52 also displays efficient mercury adsorption resulting from the stronger-binding ability beween the sulfur and the mercury and can remove 92% mercury from methanol solution even with the initial concentration as low as 100 mg/L. The results in this work indicate the feasibility of BUT-52 for the separation of light hydrocarbons and efficient adsorption/removal of mercury.

  12. Adsorption of reovirus to clay minerals: effects of cation-exchange capacity, cation saturation, and surface area.

    PubMed Central

    Lipson, S M; Stotzky, G

    1983-01-01

    The adsorption of reovirus to clay minerals has been reported by several investigators, but the mechanisms defining this association have been studied only minimally. The purpose of this investigation was to elucidate the mechanisms involved with this interaction. More reovirus type 3 was adsorbed, in both distilled and synthetic estuarine water, by low concentrations of montmorillonite than by comparable concentrations of kaolinite containing a mixed complement of cations on the exchange complex. Adsorption to the clays was essentially immediate and was correlated with the cation-exchange capacity of the clays, indicating that adsorption was primarily to negatively charged sites on the clays. Adsorption was greater with low concentrations of clays in estuarine water than in distilled water, as the higher ionic strength of the estuarine water reduced the electrokinetic potential of both clay and virus particles. The addition of cations (as chloride salts) to distilled water enhanced adsorption, with divalent cations being more effective than monovalent cations and 10(-2) M resulting in more adsorption than 10(-3) M. Potassium ions suppressed reovirus adsorption to montmorillonite, probably by collapsing the clay lattices and preventing the expression of the interlayer-derived cation-exchange capacity. More virus was adsorbed by montmorillonite made homoionic to various mono-, di-, and trivalent cations (except by montmorillonite homoionic to potassium) than by comparable concentrations of kaolinite homoionic to the same cations. The sequence of the amount of adsorption to homoionic montmorillonite was Al greater than Ca greater than Mg greater than Na greater than K; the sequence of adsorption to kaolinite was Na greater than Al greater than Ca greater than Mg greater than K. The constant partition-type adsorption isotherms obtained when the clay concentration was maintained constant and the virus concentration was varied indicated that a fixed proportion of the

  13. Enhancing adsorption capacity of toxic malachite green dye through chemically modified breadnut peel: equilibrium, thermodynamics, kinetics and regeneration studies.

    PubMed

    Chieng, Hei Ing; Lim, Linda B L; Priyantha, Namal

    2015-01-01

    Breadnut skin, in both its unmodified (KS) and base-modified (BM-KS) forms, was investigated for its potential use as a low-cost adsorbent for the removal of toxic dye, malachite green (MG). Characterization of the adsorbents was carried out using scanning electron microscope, X-ray fluorescence and Fourier transform infra-red spectroscopy. Batch adsorption experiments, carried out under optimized conditions, for the adsorption of MG were fitted using five isotherm models (Langmuir, Freundlich, Dubinin-Radushkevich, Temkin and Sips) and six error functions to determine the best-fit model. The adsorption capacity was greatly enhanced when breadnut skin was chemically modified with NaOH, leading to an adsorption capacity of 353.0 mg g(-1), that was far superior to most reported adsorbents for the removal of MG. Thermodynamics studies indicated that the adsorption of MG was spontaneous on KS and BM-KS, and the reactions were endothermic and exothermic, respectively. Kinetics studies showed that both followed the pseudo-second order. Regeneration experiments on BM-KS indicated that its adsorption capacity was still maintained at>90% even after five cycles. It can be concluded that NaOH-modified breadfruit skin has great potential to be utilized in real-life application as a low-cost adsorbent for the removal of MG in wastewater treatment.

  14. Preparation of a porous clay heterostructure and study of its adsorption capacity of phenol and chlorinated phenols from aqueous solutions.

    PubMed

    Arellano-Cárdenas, Sofía; Gallardo-Velázquez, Tzayhrí; Osorio-Revilla, Guillermo; López-Cortez, Ma del Socorro

    2008-01-01

    A porous clay heterostructure (PCH) from a Mexican clay was prepared and characterized, and its aqueous phenol and dichlorophenols (DCPs) adsorption capacities were studied using a batch equilibrium technique. The PCH displayed a surface area of 305.5 m2/g, 37.2 A average porous diameter, and a basal space of 23.2 A. The adsorption capacity shown by the PCH for both phenol and DCPs from water (14.5 mg/g for phenol; 48.7 mg/g for 3,4-DCP; and 45.5 mg/g for 2,5-DCP) suggests that the PCH has both hydrophobic and hydrophilic characteristics, as a result of the presence of silanol and siloxane groups formed during the pillaring and calcination of the PCH. The values of maximal adsorption capacity for dichlorophenols were higher than those reported for aluminum pillared clays and some inorgano-organo clays and comparable with some ionic exchange resins.

  15. The effects of urease immobilization on the transport characteristics and protein adsorption capacity of cellulose acetate based hemodialysis membranes.

    PubMed

    Mahlicli, Filiz Yasar; Altinkaya, Sacide Alsoy

    2009-10-01

    In this study, cellulose acetate (CA) based hemodialysis membranes were prepared by a dry phase inversion method and the influences of urease immobilization on the clearing performance and protein adsorption capacity of the membranes were investigated. Permeation experiments have shown that modification of CA membranes with urease immobilization not only enhanced the transport rate of urea but also increased the permeation coefficients of uric acid and creatinine by changing the structure of the membrane. Furthermore, the protein adsorption capacity of the CA membranes decreased. On the other hand, the mechanical strength of the modified CA membrane did not change significantly compared with that of the unmodified one. A mathematical model was derived to determine the rate of mass transfer of urea through modified CA membranes. Model predictions along with the experimental data suggest that urease immobilization can be used as an alternative method in preparing CA based hemodialysis membranes with improved transport characteristics and biocompatibility through reduced protein adsorption capacities.

  16. The adsorption of mercury-species on relaxed and rumpled CaO (0 0 1) surfaces investigated by density functional theory.

    PubMed

    Blowers, Paul; Kim, Bo Gyeong

    2011-03-01

    This research examines the importance of several computational choices in modeling mercury species adsorption on calcium oxide surfaces and is the second in a series of papers. The importance of surface relaxation was tested and it was found that adsorption energies changed for HgCl(2), moving adsorption from being at the borderline of physisorption and chemisorption to being strongly chemisorbed. Results for Hg and HgCl were unaffected. A second computational choice, that of the cluster or periodic model size was tested in both the plane of the model (4 × 4 or 5 × 5 model sizes) and for the depth (two or three layers). It was found that the minimum cluster size for handling mercury adsorption was 5 × 5 and that only two layers of depth were needed. The energetic results show that rumpled CaO surfaces will only weakly physisorb elemental mercury, but could be used to capture HgCl(2) from coal combustion flue gases, which is in agreement with limited experimental data.

  17. A geometric pore adsorption model for predicting the drug loading capacity of insoluble drugs in mesoporous carbon.

    PubMed

    Gao, Yikun; Zhu, Wenquan; Liu, Jia; Di, Donghua; Chang, Di; Jiang, Tongying; Wang, Siling

    2015-05-15

    In this work, a simple and accurate geometric pore-adsorption model was established and experimentally validated for predicting the drug loading capacity in mesoporous carbon. The model was designed according to the shape of pore channels of mesoporous carbon and the arrangement of drug molecules loaded in the pores. Three different small molecule drugs (celecoxib, fenofibrate and carvedilol) were respectively loaded in mesoporous carbon with different pore sizes. In order to test the accuracy of the established model, nitrogen adsorption-desorption analysis was employed to confirm the pore structure of mesoporous carbon and to calculate the occupation volume of the adsorbed drugs. The adsorption isotherms of celecoxib were systematically investigated to describe the adsorption process. It was found that the experimental results of adsorption capacity were all in the range of the predicted values for all the tested drugs and mesoporous carbon. The occupation volumes calculated from the model also agreed well with the experimental data. These results demonstrated that the established model could accurately provide the range of drug loading capacity, which may provide a useful option for the prediction of the drug loading capacity of small molecule drugs in mesoporous materials.

  18. Shape of the hydrogen adsorption regions of MOF-5 and its impact on the hydrogen storage capacity

    NASA Astrophysics Data System (ADS)

    Cabria, I.; López, M. J.; Alonso, J. A.

    2008-11-01

    The adsorption of molecular hydrogen on a metal-organic framework (MOF) material, MOF-5, has been studied using the density-functional formalism. The calculated potential-energy surface shows that there are two main adsorption regions: both near the OZn4 oxide cores at the vertices of the cubic skeleton of MOF-5. The adsorption energies in those regions are between 100 and 130 meV/molecule. Those adsorption regions have the shape of long, wide, and deep connected trenches and passage of the molecule between regions needs to surpass small barriers of 30-50 meV. The shape of these regions, and not only the presence of metal atoms, explains the large storage capacity measured for MOF-5. The elongated shape explains why some authors have previously identified only one type of adsorption site, associated to the Zn oxide core, and others identified two or three sites. One should consider adsorption regions rather than adsorption sites. A third region of adsorption is near the benzenic rings of the MOF-5. We have also analyzed the possibility of dissociative chemisorption. The chemisorption energy with respect to two separated H atoms is 1.33 eV/H atom; but, since dissociating the free molecule costs 4.75 eV, the physisorbed H2 molecule is more stable than the dissociated chemisorbed state by about 2 eV. Dissociation of the adsorbed molecule costs less energy, but the dissociation barrier is still high.

  19. Comparative study on the adsorption capacity of raw and modified litchi pericarp for removing Cu(II) from solutions.

    PubMed

    Kong, Zhenglei; Li, Xiaochen; Tian, Jiyu; Yang, Jili; Sun, Shujuan

    2014-02-15

    The adsorption of Cu(II) onto raw litchi pericarp (LP) and modified litchi pericarp (MLP) as a function of pH, adsorbent dose and contact time, were investigated. Adsorption equilibrium isotherms, kinetics, and thermodynamics were studied to characterize the adsorption process. Leaching assays were also conducted to evaluate the potential contamination risk of LP and MLP to aqueous systems. The maximum adsorption of Cu(II) onto MLP was occurred at the pH of 6.0, adsorbent dose of 10.0 g/L, and contact time of 60 min, respectively. The adsorption process of Cu(II) onto LP and MLP were described well by both Langmuir and Freundlich isotherms, and the adsorption kinetics of Cu(II) on MLP was pseudo-second-order. Cu(II) adsorption onto LP and MLP are both exothermic, while it is spontaneous for MLP, and non-spontaneous for LP. The maximum adsorption capacity of Cu(II) onto MLP was 23.70 mg/g, which was about 2.7 times higher than that of LP. Additionally, as compared to LP, the leaching amounts of TOC, TN, and TP from MLP were significantly reduced by a percentage of 27.0%, 90.3%, and 35.3%, respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Methane and CO2 Adsorption Capacities of Kerogen in the Eagle Ford Shale from Molecular Simulation.

    PubMed

    Psarras, Peter; Holmes, Randall; Vishal, Vikram; Wilcox, Jennifer

    2017-08-15

    Over the past decade, the United States has become a world leader in natural gas production, thanks in part to a large-fold increase in recovery from unconventional resources, i.e., shale rock and tight oil reservoirs. In an attempt to help mitigate climate change, these depleted formations are being considered for their long-term CO2 storage potential. Because of the variability in mineral and structural composition from one formation to the next (even within the same region), it is imperative to understand the adsorption behavior of CH4 and CO2 in the context of specific conditions and pore surface chemistry, i.e., relative total organic content (TOC), clay, and surface functionality. This study examines two Eagle Ford shale samples, both recovered from shale that was extracted at depths of approximately 3800 m and having low clay content (i.e., less than 5%) and similar mineral compositions but distinct TOCs (i.e., 2% and 5%, respectively). Experimentally validated models of kerogen were used to the estimate CH4 and CO2 adsorption capacities. The pore size distributions modeled were derived from low-pressure adsorption isotherm data using CO2 and N2 as probe gases for micropores and mesopores, respectively. Given the presence of water in these natural systems, the role of surface chemistry on modeled kerogen pore surfaces was investigated. Several functional groups associated with surface-dissociated water were considered. Pressure conditions from 10 to 50 bar were investigated using grand canonical Monte Carlo simulations along with typical outgassing temperatures used in many shale characterization and adsorption studies (i.e., 60 and 250 °C). Both CO2 and N2 were used as probe gases to determine the total pore volume available for gas adsorption spanning pore diameters ranging from 0.3 to 30 nm. The impacts of surface chemistry, outgassing temperature, and the inclusion of nanopores with diameters of less than 1.5 nm were determined for applications of CH4

  1. Synthesis of multi-walled carbon nanotubes/β-FeOOH nanocomposites with high adsorption capacity

    NASA Astrophysics Data System (ADS)

    Song, Hao-Jie; Liu, Lei; Jia, Xiao-Hua; Min, Chunying

    2012-12-01

    A hybrid nanostructure of multi-walled carbon nanotubes (CNTs) and β-ferric oxyhydroxide (β-FeOOH) nanoparticles is synthesized by ultrasonic-assisted in situ hydrolysis of the precursor ferric chloride and CNTs. Characterization by X-ray diffraction, scanning electron microscopy , and transmission electron microscopy establishes the nanohybrid structure of the synthesized sample. The results revealed that the surface of CNTs was uniformly assembled by numerous β-FeOOH nanoparticles and had an average diameter of 3 nm. The formation route of anchoring β-FeOOH nanoparticles onto CNTs was proposed as the intercalation and adsorption of iron ions onto the wall of CNTs, followed by the nucleation and growth of β-FeOOH nanoparticles. The values of remanent magnetization ( M r) and coercivity ( H c) of the as-synthesized CNTs/β-FeOOH nanocomposites were 0.1131 emu g, and 490.824 Oe, respectively. Furthermore, CNTs/β-FeOOH nanocomposites showed a very high adsorption capacity of Congo red and thus these nanocomposites can be used as good adsorbents and can be used for the removal of the dye of Congo red from the waste water system.

  2. 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.

  3. 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.

  4. Filtration capacity on rapid filters and adsorption characteristics of polystyrene granules.

    PubMed

    Schöntag, Juliana M; Moreira, Filipe M; Sens, Maurício L

    2017-08-01

    Polystyrene (PS) beads have been studied as a possible filter element, with the aim of increasing the effective production of water in treatment plants. Being a granular material of an effective size of 0.68 mm, sphericity of 0.96 and density of 1046 kg/m(3), the use of PS beads may provide washing water savings because they require low velocities for expansion during backwash. However, other aspects must be considered before the adoption of this material, such as the filtration mechanisms associated with it. Analyses of turbidity retention and head loss variation throughout the filter run were observed, and acceptable filtration rates were achieved (pilot tests). There was bit adhesion of particulates on bead surfaces, which was observed by scanning electron microscopy. The beads showed a low adsorption capacity, which was assessed using methylene blue (lab tests).

  5. Integrated Removal of NOx with Carbon Monoxide as Reductant, and Capture of Mercury in a Low Temperature Selective Catalytic and Adsorptive Reactor

    SciTech Connect

    Neville Pinto; Panagiotis Smirniotis; Stephen Thiel

    2010-08-31

    Coal will likely continue to be a dominant component of power generation in the foreseeable future. This project addresses the issue of environmental compliance for two important pollutants: NO{sub x} and mercury. Integration of emission control units is in principle possible through a Low Temperature Selective Catalytic and Adsorptive Reactor (LTSCAR) in which NO{sub x} removal is achieved in a traditional SCR mode but at low temperature, and, uniquely, using carbon monoxide as a reductant. The capture of mercury is integrated into the same process unit. Such an arrangement would reduce mercury removal costs significantly, and provide improved control for the ultimate disposal of mercury. The work completed in this project demonstrates that the use of CO as a reductant in LTSCR is technically feasible using supported manganese oxide catalysts, that the simultaneous warm-gas capture of elemental and oxidized mercury is technically feasible using both nanostructured chelating adsorbents and ceria-titania-based materials, and that integrated removal of mercury and NO{sub x} is technically feasible using ceria-titania-based materials.

  6. Changing the adsorption capacity of coal-based honeycomb monoliths for pollutant removal from liquid streams by controlling their porosity

    NASA Astrophysics Data System (ADS)

    Gatica, José M.; Harti, Sanae; Vidal, Hilario

    2010-09-01

    Coal-based honeycomb monoliths extruded using methods developed for ceramic materials have been used to retain methylene blue and p-nitrophenol from aqueous solutions. The influence of the filters' thermal treatment on their textural properties and performance as adsorbents was examined. Characterization by N 2 physisorption, mercury porosimetry and scanning electron microscopy along with adsorption tests under dynamic conditions suggest that, depending on the pollutant and its initial concentration, it can be more convenient to previously submit the monoliths to a simple carbonization or to an additional activation, with or without preoxidation, as a consequence of their different resulting pore structures. Infrared spectroscopy indicates that their different adsorption behaviour seems not to be related to differences in their surface chemical groups. In addition, axial crushing tests show that the monoliths have an acceptable mechanical resistance for the application investigated.

  7. Copper Accumulation, Availability and Adsorption Capacity in Sandy Soils of Vineyards with Different Cultivation Duration

    NASA Astrophysics Data System (ADS)

    Mallmann, F. J. K.; Miotto, A.; Bender, M. A.; Gubiani, E.; Rheinheimer, D. D. S.; Kaminski, J.; Ceretta, C. A.; Šimůnek, J.

    2015-12-01

    Bordeaux mixture is a copper-based (Cu) fungicide and bactericide applied in vineyards to control plant diseases. Since it is applied several times per year, it accumulates in large quantities on plants and in soil. This study evaluates the Cu accumulation in, and desorption kinetics and adsorption capability of a sandy Ultisol in a natural field and in 3 vineyards for 5 (V1), 11 (V2), and 31 (V3) years in South of Brazil. Soil samples were collected in 8 depths (0-60 cm) of all four soil profiles, which all displayed similar soil properties. The following soil properties were measured: pH, organic matter (OM), soil bulk density, Cu total concentration, and Cu desorption and adsorption curves. A two first-order reactions model and the Langmuir isotherm were fitted to the desorption and adsorption curves, respectively. An increase in the total mass of Cu in the vineyards followed a linear regression curve, with an average annual increase of 7.15 kg ha-1. Cu accumulated down to a depth of 5, 20, and 30 cm in V1, V2 and V3, respectively, with the highest Cu content reaching 138.4 mg kg-1 in the 0-5 cm soil layer of V3. Cu desorption parameters showed a high correlation with its total concentration. Approximately 57 and 19% of total Cu were immediately and slowly available, respectively, indicating a high potential for plant absorption and/or downward movement. Cu concentrations extracted by EDTA from soil layers not affected by anthropogenic Cu inputs were very low. The maximum Cu adsorption capacity of the 0-5 and 5-10 cm soil layers increased with the vineyard age, reaching concentrations higher than 900 mg kg-1. This increase was highly related to OM and pH, which both increased with cultivation duration. Despite of low clay content of these soils, there is low risk of groundwater Cu contamination for actual conditions. However, high Cu concentrations in the surface layer of the long-term vineyards could cause toxicity problems for this and for companion crops.

  8. Effect of the both texture and electrical properties of activated carbon on the CO{sub 2} adsorption capacity

    SciTech Connect

    Djeridi, W.; Ouederni, A.; Mansour, N.Ben; Llewellyn, P.L.; Alyamani, A.; El Mir, L.

    2016-01-15

    Highlights: • A series of activated carbon pellet without binder was prepared by chemical activation. • Carbon dioxide storage isotherm at 30 °C and up to 25 bars was measured for the microporous carbon. • Adsorption enthalpies have been correlated with the carbon dioxide uptake. • Pyrolysis temperature effect on the electrical conductivity of the samples. • Impact of the both texture and electrical properties on CO{sub 2} adsorption capacity have been deducted - Abstract: A series of activated carbon pellets (ACP) based on olive stones were studied for CO{sub 2} storage application. The surface area, pore volume, and pore diameter were evaluated from the analysis of N{sub 2} adsorption isotherm data. The characterization of carbon materials was performed by scanning electron microscopy (SEM), the powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM). The adsorption enthalpies were obtained by microcalorimetry. The effect of pyrolysis temperature on textural, electrical conductivity and gas adsorption capacities of the ACP were investigated by adsorbing CO{sub 2} at 303 K in the pressure range of 0–2.3 MPa. In fact the electrical conductivity is strongly affected by the microporosity of the samples and the size of the micropore. It increases when the pore size decreases which affect the CO{sub 2} adsorption. Also with increases temperature the free electrons concentration on the surface increases which affect the interaction of the adsorbed gas molecules.

  9. Adsorption characteristics of adsorbent resins and antioxidant capacity for enrichment of phenolics from two-phase olive waste.

    PubMed

    Wang, Zhihong; Wang, Chengzhang; Yuan, Jiaojiao; Zhang, Changwei

    2017-01-01

    In this study, the adsorption properties of nine resins including polyamide resin (30-60), polyamide resin (60-100) AB-8, S-8, D-101, NKA-9, NKA-II, XDA-1 and XDA-4 for enrichment phenolics of the olive waste were investigated. XDA-1 and NKA-II were chosen for further study due to their outstanding adsorption and desorption capacity. XDA-1 and NKA-II had similar adsorption and desorption behaviors for phenolics of olive waste. The adsorption mechanism could be better explained by pseudo second-order kinetics model and Freundlich isotherm model, and the adsorption processes were spontaneously and exothermic. The experiment of gradient elution were carried out through treated XDA-1 resins column, the result indicated the total phenolics were mainly obtained from the 40% and 60% ethanol fraction. The order of antioxidant capacity by DPPH  , ABTS(+) radical and FRAP assay was similar with the content of phenolics from fraction elution. The compositions of phenolics from different elution fractions were determined by reversed phase-HPLC-DAD method. Gallic acid, hydroxytyrosol, tyrosol and ferulic acid were the major constituent in the fraction elute, and the content of hydroxytyrosol reached to the 41.69mg/g. The above results revealed the synergistic effects of the different phenolics contribute to the antioxidant capacity.

  10. Textural characterization of native and n-alky-bonded silica monoliths by mercury intrusion/extrusion, inverse size exclusion chromatography and nitrogen adsorption.

    PubMed

    Thommes, M; Skudas, R; Unger, K K; Lubda, D

    2008-05-16

    Native and n-alkyl-bonded (n-octadecyl) monolithic silica rods with mesopores in the range between 10 and 25 nm and macropores in the range between 1.8 and 6.0 microm were examined by mercury intrusion/extrusion, inverse size exclusion chromatography (ISEC) and nitrogen sorption. Our results reveal very good agreement for the mesopore size distribution obtained from nitrogen adsorption (in combination with an advanced NLDFT analysis) and ISEC. Our studies highlight the importance of mercury porosimetry for the assessment of the macropore size distribution and show that mercury porosimetry is the only method which allows obtaining a combined and comprehensive structural characterization of macroporous/mesoporous silica monoliths. Our data clearly confirm that mercury porosimetry hysteresis and entrapment have different origin, and indicate the intrinsic nature of mercury porosimetry hysteresis in these silica monoliths. Within this context some silica monoliths show the remarkable result of no entrapment of mercury after extrusion from the mesopore system (i.e. for the first intrusion/extrusion cycle). The results of a systematic study of the mercury intrusion/extrusion behavior into native silica monoliths and monoliths with bonded n-alkyl groups reveals that the macro (through) pore structure, which controls the mass transfer to and from the mesopores, here mainly controls the entrapment behavior. Our data suggest that mercury intrusion/extrusion porosimetry does not only allow to obtain a comprehensive pore structure analysis, but can also serve as a tool to estimate the mass transport properties of silica monoliths to be employed in liquid-phase separation processes.

  11. Volumetric Interpretation of Protein Adsorption: Ion-Exchange Adsorbent Capacity, Protein pI, and Interaction Energetics

    PubMed Central

    Noh, Hyeran; Yohe, Stefan; Vogler, Erwin A.

    2008-01-01

    Adsorption of lysozyme (Lys), human serum albumin (HSA), and immunoglobulin G (IgG) to anion- and cation-exchange resins is dominated by electrostatic interactions between protein and adsorbent. The solution-depletion method of measuring adsorption shows, however, that these proteins do not irreversibly adsorb to ion-exchange surfaces, even when the charge disparity between adsorbent and protein inferred from protein pI is large. Net-positively-charged Lys (pI = 11) and net-negatively-charged HSA (pI = 5.5) adsorb so strongly to sulfopropyl sepharose (SP; a negatively-charged, strong cation exchange resin, −0.22 mmol/mL exchange capacity) that both resist displacement by net-neutral IgG (pI = 7.0) in simultaneous adsorption-competition experiments. By contrast, IgG readily displaces both Lys and HSA adsorbed either to quarternary-ammonium sepharose (Q; a positively-charged, strong anion exchanger, + 0.22 mmol/mL exchange capacity) or octadecyl sepharose (ODS, a neutral hydrophobic resin, 0 mmol/mL exchange capacity). Thus it is concluded that adsorption results do not sensibly correlate with protein pI and that pI is actually a rather poor predictor of affinity for ion-exchange surfaces. Adsorption of Lys, HSA, and IgG to ion-exchange resins from stagnant solution leads to adsorbed multi-layers, into-or-onto which IgG adsorbs in adsorption-competition experiments. Comparison of adsorption to ion-exchange resins and neutral ODS leads to the conclusion that the apparent standard free-energy-of-adsorption ΔGadso of Lys, HSA, and IgG is not large in comparison to thermal energy due to energy-compensating interactions between water, protein, and ion-exchange surfaces that leaves a small net ΔGadso. Thus water is found to control protein adsorption to a full range of substratum types spanning hydrophobic (poorly water wettable) surfaces, hydrophilic surfaces bearing relatively-weak Lewis acid/base functionalities that wet with (hydrogen bond to) water but do not

  12. Surface-Energetic Heterogeneity of Nanoporous Solids for CO2 and CO Adsorption: The Key to an Adsorption Capacity and Selectivity at Low Pressures.

    PubMed

    Kim, Moon Hyeon; Cho, Il Hum; Choi, Sang Ok; Lee, In Soo

    2016-05-01

    This study has been focused on surface energetic heterogeneity of zeolite (H-mordenite, "HM"), activated carbon ("RB2") and metal-organic framework family ("Z1200") materials and their isotherm features in adsorption of CO2 and CO at 25 degrees C and low pressures ≤ 850 Torr. The nanoporous solids showed not only distinctive shape of adsorption isotherms for CO2 with relatively high polarizability and quadrupole moment but also different capacities in the CO2 adsorption. These differences between the adsorbents could be well correlated with their surface nonuniformity. The most heterogeneous surfaces were found with the HM that gave the highest CO2 uptake at all pressures allowed, while the Z1200 consisted of completely homogeneous surfaces and even CO2 adsorption linearly increased with pressure. An intermediate character was indicated on the surface of RB2 and thus this sorbent possessed isotherm features between the HM and Z1200 in CO2 adsorption. Such different surface energetics was fairly consistent with changes in CO2/CO selectivity on the nanoporous adsorbents up to equilibrated pressures near 850 Torr.

  13. Synthesis, characterisation and adsorption properties of a porous copper(II) 3D coordination polymer exhibiting strong binding enthalpy and adsorption capacity for carbon dioxide.

    PubMed

    Eckold, Pierre; Gee, William J; Hill, Matthew R; Batten, Stuart R

    2012-11-21

    The synthesis and characterisation of microporous coordination polymers containing copper(II) or cobalt(II) and 2-(pyridin-4-yl)malonaldehyde (Hpma) is described and the gas adsorption properties evaluated. Single-crystal X-ray structure determinations identified the structures as [M(pma)(2)]·2X (M = Cu, 1; Co, 2; X = MeOH, MeCN), which contain 3D networks with rutile topology and continuous 1D rectangular channels with diameters ranging from 3 to 4 Å. The materials exhibit low BET surface areas of 143 m(2) g(-1), but possess large capacities for carbon dioxide capture of 14.1 wt%. The small pore channels are shown to account for this, delivering a particularly strong binding enthalpy to adsorbed CO(2) of 38 kJ mol(-1), and a very large adsorption capacity relative to the low surface area.

  14. Expanded porous MOF-505 analogue exhibiting large hydrogen storage capacity and selective carbon dioxide adsorption.

    PubMed

    Zheng, Baishu; Yun, Ruirui; Bai, Junfeng; Lu, Zhiyong; Du, Liting; Li, Yizhi

    2013-03-18

    An expanded 4,4-paddlewheel-connected porous MOF-505-type metal-organic framework (MOF), [Cu2(PDEB)(H2O)2]·xS (NJU-Bai12; NJU-Bai represents the Nanjing University Bai group and S represents noncoordinated solvent molecules) has been designed from a nanosized rectangular diisophthalate linker containing alkyne groups 5,5'-(1,4-phenylenedi-2,1-ethynediyl)bis(1,3-benzenecarboxylic acid). This MOF material possesses permanent microporosity with the highest Brunauer-Emmett-Teller surface area of 3038 m(2)·g(-1) and the largest unsaturated total hydrogen storage capacity of 62.7 mg·g(-1) at 77 K and 20 bar among reported MOF-505 analogues. Additionally, NJU-Bai12 also exhibits excellent carbon dioxide (CO2) uptake capacity (23.83 and 19.85 mmol·g(-1) at 20 bar for 273 and 298 K, respectively) and selective gas adsorption properties with CO2/CH4 selectivity of 5.0 and CO2/N2 selectivity of 24.6 at room temperature.

  15. Cu(II) and Zn(II) adsorption capacity of three different clay liner materials.

    PubMed

    Musso, T B; Parolo, M E; Pettinari, G; Francisca, F M

    2014-12-15

    Sorption of Cu(II) and Zn(II) on three natural clays meeting the international requirements for use as liners was evaluated by means of batch tests. The purpose of this research was to determine the retention capacities of the clays for metal cations commonly present in urban solid waste leachates. The pH and ionic strength conditions were set at values frequently found in real leachates. The changes observed in the XRD patterns and FTIR spectra upon adsorption can be considered an evidence of clay-metal electrostatic interaction. The Langmuir model was found to best describe the sorption processes, offering maximum sorption capacities from 8.16 to 56.89 mg/g for Cu(II) and from 49.59 to 103.83 mg/g for Zn(II). All samples remove more Zn(II) than Cu(II), which may be related to the different geometry of the hydrated Cu(II) cation. The total amount of metal sorption was strongly influenced by the total specific surface area, the presence of carbonates and the smectite content of the clays. In addition to their known quality as physical barriers, the adsorbed amounts obtained indicate the suitability of the tested clays to contribute to the retardation of Cu(II) and Zn(II) transport through clay liners.

  16. High adsorption capacity of heavy metals on two-dimensional MXenes: an ab initio study with molecular dynamics simulation.

    PubMed

    Guo, Xun; Zhang, Xitong; Zhao, Shijun; Huang, Qing; Xue, Jianming

    2016-01-07

    Density functional theory (DFT) calculation is employed to study the adsorption properties of Pb and Cu on recently synthesized two-dimensional materials MXenes, including Ti3C2, V2C1 and Ti2C1. The influence of surface decoration with functional groups such as H, OH and F have also been investigated. Most of these studied MXenes exhibit excellent capability to adsorb Pb and Cu, especially the adsorption capacity of Pb on Ti2C1 is as high as 2560 mg g(-1). Both the binding energies and the adsorption capacities are sensitive to the functional groups attached to the MXenes' surface. Ab initio molecular dynamics (ab-init MD) simulation confirms that Ti2C1 remains stable at room temperature after adsorbing Pb atoms. Our calculations imply that these newly emerging two-dimensional MXenes are promising candidates for wastewater treatment and ion separation.

  17. EFFECT OF MOLECULAR OXYGEN ON ADSORPTIVE CAPACITY AND EXTRACTION EFFICIENCY OF GRANULATED ACTIVATED CARBON FOR THREE ORTHO-SUBSTITUTED PHENOLS

    EPA Science Inventory

    Adsorptive capacity of activated carbon for several organic compounds was found to be strongly influenced by the presence of molecular oxygen. This influence is manifested by the polymerization of adsorbate on the surface of activated carbon. As a result, GAC exhibits much high...

  18. EFFECT OF MOLECULAR OXYGEN ON ADSORPTIVE CAPACITY AND EXTRACTION EFFICIENCY OF GRANULATED ACTIVATED CARBON FOR THREE ORTHO-SUBSTITUTED PHENOLS

    EPA Science Inventory

    Adsorptive capacity of activated carbon for several organic compounds was found to be strongly influenced by the presence of molecular oxygen. This influence is manifested by the polymerization of adsorbate on the surface of activated carbon. As a result, GAC exhibits much high...

  19. Mercury species, selenium, metallothioneins and glutathione in two dolphins from the southeastern Brazilian coast: Mercury detoxification and physiological differences in diving capacity.

    PubMed

    Kehrig, Helena A; Hauser-Davis, Rachel A; Seixas, Tercia G; Pinheiro, Ana Beatriz; Di Beneditto, Ana Paula M

    2016-06-01

    In the present study, the concentration of trace elements, total mercury (Hg) and selenium (Se) and mercury forms (MeHg, Hginorg and HgSe) in the vulnerable coastal dolphins Pontoporia blainvillei and Sotalia guianensis were appraised and compared, using metallothioneins (MT) and glutathione (GSH) as biomarkers for trace element exposure. The trace element concentrations varied between muscle and liver tissues, with liver of all dolphin specimens showing higher Hg and Se concentrations than those found in muscle. Hg, MeHg and Hginorg molar concentrations showed a clear increase with Se molar concentrations in the liver of both dolphins, and Se concentrations were higher than those of Hg on a molar basis. Se plays a relevant role in the detoxification of MeHg in the hepatic tissue of both dolphins, forming Hg-Se amorphous crystals in liver. In contrast, MT were involved in the detoxification process of Hginorg in liver. GSH levels in P. blainvillei and S. guianensis muscle tissue suggest that these dolphins have different diving capacities. Muscle Hg concentrations were associated to this tripeptide, which protects dolphin cells against Hg stress.

  20. A Novel Exopolysaccharide with Metal Adsorption Capacity Produced by a Marine Bacterium Alteromonas sp. JL2810

    PubMed Central

    Zhang, Zilian; Cai, Ruanhong; Zhang, Wenhui; Fu, Yingnan; Jiao, Nianzhi

    2017-01-01

    Most marine bacteria can produce exopolysaccharides (EPS). However, very few structures of EPS produced by marine bacteria have been determined. The characterization of EPS structure is important for the elucidation of their biological functions and ecological roles. In this study, the structure of EPS produced by a marine bacterium, Alteromonas sp. JL2810, was characterized, and the biosorption of the EPS for heavy metals Cu2+, Ni2+, and Cr6+ was also investigated. Nuclear magnetic resonance (NMR) analysis indicated that the JL2810 EPS have a novel structure consisting of the repeating unit of [-3)-α-Rhap-(1→3)-α-Manp-(1→4)-α-3OAc-GalAp-(1→]. The biosorption of the EPS for heavy metals was affected by a medium pH; the maximum biosorption capacities for Cu2+ and Ni2+ were 140.8 ± 8.2 mg/g and 226.3 ± 3.3 mg/g at pH 5.0; however, for Cr6+ it was 215.2 ± 5.1 mg/g at pH 5.5. Infrared spectrometry analysis demonstrated that the groups of O-H, C=O, and C-O-C were the main function groups for the adsorption of JL2810 EPS with the heavy metals. The adsorption equilibrium of JL2810 EPS for Ni2+ was further analyzed, and the equilibrium data could be better represented by the Langmuir isotherm model. The novel EPS could be potentially used in industrial applications as a novel bio-resource for the removal of heavy metals. PMID:28604644

  1. Efficient Removal of Co2+ from Aqueous Solution by 3-Aminopropyltriethoxysilane Functionalized Montmorillonite with Enhanced Adsorption Capacity

    PubMed Central

    Huang, Zhujian; Gong, Beini; Dai, Yaping; Chiang, Pen-Chi; Lai, Xiaolin; Yu, Guangwei

    2016-01-01

    To achieve a satisfactory removal efficiency of heavy metal ions from wastewater, silane-functionalized montmorillonite with abundant ligand-binding sites (-NH2) was synthesized as an efficient adsorbent. Ca-montmorillonite (Ca-Mt) was functionalized with 3-aminopropyl triethoxysilane (APTES) to obtain the APTES-Mt products (APTES1.0CEC-Mt, APTES2.0CEC-Mt, APTES3.0CEC-Mt, APTES4.0CEC-Mt) with enhanced adsorption capacity for Co2+. The physico-chemical properties of the synthesized adsorbents were characterized by spectroscopic and microscopic methods, and the results demonstrated that APTES was successfully intercalated into the gallery of Ca-Mt or grafted onto the surface of Ca-Mt through Si-O bonds. The effect of solution pH, ionic strength, temperature, initial concentrations and contact time on adsorption of Co2+ by APTES-Mt was evaluated. The results indicated that adsorption of Co2+ onto Ca-Mt, APTES1.0CEC-Mt and APTES2.0CEC-Mt can be considered to be a pseudo-second-order process. In contrast, adsorption of Co2+ onto APTES3.0CEC-Mt and APTES4.0CEC-Mt fitted well with the pseudo-first-order kinetics. The adsorption isotherms were described by the Langmuir model, and the maximum adsorption capacities of APTES1.0CEC-Mt, APTES2.0CEC-Mt, APTES3.0CEC-Mt and APTES4.0CEC-Mt were 25.1, 33.8, 61.6, and 61.9 mg·g-1, respectively. In addition, reaction temperature had no impact on the adsorption capacity, while both the pH and ionic strength significantly affected the adsorption process. A synergistic effect of ion exchange and coordination interactions on adsorption was observed, thereby leading to a significant enhancement of Co2+ adsorption by the composites. Thus, APTES-Mt could be a cost-effective and environmental-friendly adsorbent, with potential for treating Co2+-rich wastewater. PMID:27448094

  2. Effects of decreasing activated carbon particle diameter from 30 μm to 140 nm on equilibrium adsorption capacity.

    PubMed

    Pan, Long; Nishimura, Yuki; Takaesu, Hideki; Matsui, Yoshihiko; Matsushita, Taku; Shirasaki, Nobutaka

    2017-08-01

    The capacity of activated carbon particles with median diameters (D50s) of >∼1 μm for adsorption of hydrophobic micropollutants such as 2-methylisolborneol (MIB) increases with decreasing particle size because the pollutants are adsorbed mostly on the exterior (shell) of the particles owing to the limited diffusion penetration depth. However, particles with D50s of <1 μm have not been thoroughly investigated. Here, we prepared particles with D50s of ∼30 μm-∼140 nm and evaluated their adsorption capacities for MIB and several other environmentally relevant adsorbates. The adsorption capacities for low-molecular-weight adsorbates, including MIB, deceased with decreasing particle size for D50s of less than a few micrometers, whereas adsorption capacities increased with decreasing particle size for larger particles. The oxygen content of the particles increased substantially with decreasing particle size for D50s of less than a few micrometers, and oxygen content was negatively correlated with adsorption capacity. The decrease in adsorption capacity with decreasing particle size for the smaller particles was due to particle oxidation during the micromilling procedure used to decrease D50 to ∼140 nm. When oxidation was partially inhibited, the MIB adsorption capacity decrease was attenuated. For high-molecular-weight adsorbates, adsorption capacity increased with decreasing particle size over the entire range of tested particle sizes, even though particle oxygen content increased with decreasing particle size. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Capture of mercury ions by natural and industrial materials.

    PubMed

    Di Natale, F; Lancia, A; Molino, A; Di Natale, M; Karatza, D; Musmarra, D

    2006-05-20

    In this paper the technical feasibility of various adsorbents for mercury removal from contaminated waters has been studied. Adsorption isotherms of mercury ions in aqueous solution have been experimentally measured on a granular activated carbon (Aquacarb 207EA), a char, a pozzolana and a yellow tuff. The experimental evidences show that the mercury capture capacity of yellow tuff and char is of few tenths of milligrams per gram of sorbent while for the pozzolana and the activated carbon this value is of the order of 1mg/g of sorbent. Moreover, for a mercury concentration as high as 3000 microg/l the pozzolana shows the highest adsorption capacity. This result seems to be quite interesting, especially in consideration of the extremely low cost of this natural sorbent.

  4. High capacity MnOx:ZrO2 sorbent for elementary mercury capture: preparation, characterization and comparison to other sorbents

    NASA Astrophysics Data System (ADS)

    Lakatos, J.; Snape, C. E.

    2017-02-01

    Manganese oxide-zirconia type (MnOx:ZrO2) sorbents were prepared using the sol-gel technique by co precipitation ZrO(NO3)2.xH2O and Mn(NO3)2 xH2O. The heat treatment below 500°C resulted a high surface area solid structure which consists of amorphous Mn2O3 (Bixbyite) and amorphous ZrO2 phases. This material was found a high capacity oxidative sorbent for mercury removal from gas streams.

  5. Evaluation of the Memory Effect on Gold-Coated Silica Adsorption Tubes Used for the Analysis of Gaseous Mercury by Cold Vapor Atomic Absorption Spectrometry

    PubMed Central

    Rahman, Mohammad Mahmudur; Brown, Richard J. C.; Yoon, Hye-On; Phan, Nhu-Thuc

    2013-01-01

    In an effort to reduce the experimental bias involved in the analysis of gaseous elemental mercury (Hgo), the blank response from gold-coated adsorption tubes has been investigated using cold vapor atomic absorption spectrometry (CVAAS). Our study has been compared with our recent investigation on memory effect in a cold vapour atomic fluorescence spectrometry (CVAFS). The pattern of blank responses was quantified after loading different amounts of mercury and after different time intervals of 1, 14, and 45 days. In case of the one day interval, the result of five to six instant blank heating cycles confirmed successful liberation of mercury following the second and third blank heating cycles. The results of 14 or 45 days generally suggest that liberation of excess mercury is affected by both the initial loading amount and the length of storage time prior to analysis. We have demonstrated a possibly effective way to reduce memory effects. Some similarities of these results with those from CVAFS experiment suggests that the blank response is caused by a combination of mercury absorbed within the bulk gold and micro- and nanoparticles liberated during heating and not from coabsorbing interfering gaseous species. PMID:23589708

  6. Evaluation of the memory effect on gold-coated silica adsorption tubes used for the analysis of gaseous mercury by cold vapor atomic absorption spectrometry.

    PubMed

    Rahman, Mohammad Mahmudur; Brown, Richard J C; Kim, Ki-Hyun; Yoon, Hye-On; Phan, Nhu-Thuc

    2013-01-01

    In an effort to reduce the experimental bias involved in the analysis of gaseous elemental mercury (Hg(o)), the blank response from gold-coated adsorption tubes has been investigated using cold vapor atomic absorption spectrometry (CVAAS). Our study has been compared with our recent investigation on memory effect in a cold vapour atomic fluorescence spectrometry (CVAFS). The pattern of blank responses was quantified after loading different amounts of mercury and after different time intervals of 1, 14, and 45 days. In case of the one day interval, the result of five to six instant blank heating cycles confirmed successful liberation of mercury following the second and third blank heating cycles. The results of 14 or 45 days generally suggest that liberation of excess mercury is affected by both the initial loading amount and the length of storage time prior to analysis. We have demonstrated a possibly effective way to reduce memory effects. Some similarities of these results with those from CVAFS experiment suggests that the blank response is caused by a combination of mercury absorbed within the bulk gold and micro- and nanoparticles liberated during heating and not from coabsorbing interfering gaseous species.

  7. Development of impregnated sorbents for the control of elemental mercury emissions from coal-fired power plants

    SciTech Connect

    Vidic, R.D.; Kwon, S.J.; Siler, D.P.

    1999-07-01

    Sulfur-impregnated activated carbon developed in the laboratory showed superior performance for mercury uptake in comparison to other potential sorbents. The objective of this study was to evaluate whether a different sulfur impregnation protocol using hydrogen sulfide as a sulfur source can produce an equally effective mercury sorbent. In addition, several other impregnates (copper chloride, anthraquinone, picolyl amine, and thiol) were evaluated for their ability to enhance adsorptive capacity of virgin activated carbon for elemental mercury. The effect of sulfur impregnation method on mercury removal efficiency was examined using impregnation with elemental sulfur (BPLS) at high temperature and hydrogen sulfide oxidation (BPLH-series) at low impregnation temperature. The performance of both BPLS and BPLH-series increased significantly over the virgin BPL carbon. BPL impregnated for 0.25 hr (BPLH-0.25) showed best performance for mercury adsorption. Although BPLS and BPLH-0.25 had similar sulfur content, BPLS showed much better performance. The dynamic adsorption capacity of BPL carbon impregnated with copper chloride (BPLC) was found to increase with an increase in empty bed contact time and chloride content and to decrease with an increase in process temperature. All chloride impregnated activated carbons exhibited appreciable initial mercury breakthrough due to slow kinetics of mercury uptake, while substantial concentrations of oxidized mercury species were detected in the effluent from a fixed-bed adsorber. The BPL impregnated with anthraquinone and thiol exhibited high dynamic adsorption capacities at 25 C, but had much lower dynamic adsorption capacities at 140 C. BPL impregnated with picolyl amine (BPLP) exhibited very poor dynamic adsorption capacities at both 25 and 140 C. The chelating agent-impregnated carbons exhibited lower dynamic adsorption capacities than BPLS.

  8. Elemental mercury oxidation and adsorption on magnesite powder modified by Mn at low temperature.

    PubMed

    Xu, Yalin; Zhong, Qin; Liu, Xinya

    2015-01-01

    Mn modified the commercial magnesite powder prepared by wet impregnation method has been shown to be effective for gas-phase elemental mercury (Hg(0)) removal at low temperatures. The prepared samples are characterized in detail across multiform techniques: XRF, BET, SEM-EDX, XRD, H2-TPR, and XPS, and all the results show that the amorphous MnO2 impregnated on magnesite powder improves the removal efficiency of Hg(0). Through further analysis by TG and in situ FTIR, the reasonable removal mechanism is also speculated. The results indicate that chemisorbed oxygen is an important reactant in the heterogeneous reaction, and gas-phase Hg(0) is adsorbed and then oxidized to solid MnHgO3 on the surface of the adsorbent.

  9. Edge-functionalized nanoporous carbons for high adsorption capacity and selectivity of CO2 over N2

    NASA Astrophysics Data System (ADS)

    Zhou, Sainan; Guo, Chen; Wu, Zhonghua; Wang, Maohuai; Wang, Zhaojie; Wei, Shuxian; Li, Shaoren; Lu, Xiaoqing

    2017-07-01

    Single-component adsorption and competitive behavior of binary CO2/N2 mixture in the edge-functionalized nanoporous carbons (NPCs) were investigated by grand canonical Monte Carlo simulation. Results demonstrated that edge-functionalization effectively improved the pore topology and morphological characteristics of NPCs. Evaluation of adsorption capacity and analyses of the isosteric heat and radial distribution functions confirmed that edge-functionalization can evidently enhance the single-component adsorption of CO2/N2. Temperature had a negative effect on the single-component adsorption of CO2/N2 whereas pressure had a positive effect before adsorption reaches a stable equilibrium state. Edge-functionalization can significantly increase the selectivity of CO2 over N2 in NPCs, which demonstrate the following sequence according to selectivity: NH2sbnd NPC > COOHsbnd NPC > OHsbnd NPC > Hsbnd NPC > NPC. The increased CO2 molar fraction in the binary CO2/N2 mixture decreased the selectivity and saturation pressure to reach a stable equilibrium state. Overall, this work highlighted the effects of edge-functionalization on the adsorption and separation of CO2/N2 in NPCs, and provided an effective strategy for designing and screening adsorbent materials for carbon capture and separation.

  10. Determination of the antiretroviral drug nevirapine in diluted alkaline electrolyte by adsorptive stripping voltammetry at the mercury film electrode.

    PubMed

    Castro, Arnaldo Aguiar; Aucélio, Ricardo Queiroz; Rey, Nicolás Adrián; Miguel, Eliane Monsores; Farias, Percio Augusto Mardini

    2011-01-01

    This paper describes a stripping method for the determination of nevirapine at the submicromolar concentration levels. The method is based on controlled adsorptive accumulation of nevirapine at thin-film mercury electrode, followed by a linear cyclic scan voltammetry measurement of the surface species. Optimal experimental conditions include a 2.0 x 10(-3) mol L(-1) NaOH solution (supporting electrolyte), an accumulation potential of -0.20 V, and a scan rate of 100 mV s(-1). The response of nevirapine is linear over the concentration range 0.01-0.14 ppm. For an accumulation time of 6 minutes, the detection limit was found to be 0.87 ppb (3.0 x 10(-9) mol L(-1)). More convenient methods to measure the nevirapine in presence of the efavirenz, acyclovir, didanosine, indinavir, nelfinavir, saquinavir, lamivudine, zidovudine and metals ions were also investigated. The utility of this method is demonstrated by the presence of nevirapine together with ATP or DNA.

  11. Determination of Xanthine in the Presence of Hypoxanthine by Adsorptive Stripping Voltammetry at the Mercury Film Electrode

    PubMed Central

    Farias, Percio Augusto Mardini; Castro, Arnaldo Aguiar

    2014-01-01

    A stripping method for the determination of xanthine in the presence of hypoxanthine at the submicromolar concentration levels is described. The method is based on controlled adsorptive accumulation at the thin-film mercury electrode followed by a fast linear scan voltammetric measurement of the surface species. Optimum experimental conditions were found to be the use of 1.0 × 10−3 mol L−1 NaOH solution as supporting electrolyte, an accumulation potential of 0.00 V for xanthine and −0.50 V for hypoxanthine–copper, and a linear scan rate of 200 mV second−1. The response of xanthine is linear over the concentration ranges of 20–140 ppb. For an accumulation time of 30 minutes, the detection limit was found to be 36 ppt (2.3 × 10−10 mol L−1). Adequate conditions for measuring the xanthine in the presence of hypoxanthine, copper and other metals, uric acid, and other nitrogenated bases were also investigated. The utility of the method is demonstrated by the presence of xanthine associated with hypoxanthine, uric acid, nitrogenated bases, ATP, and ssDNA. PMID:24940040

  12. Determination of the Antiretroviral Drug Acyclovir in Diluted Alkaline Electrolyte by Adsorptive Stripping Voltammetry at the Mercury Film Electrode

    PubMed Central

    Castro, Arnaldo Aguiar; Cordoves, Ana Isa Perez; Farias, Percio Augusto Mardini

    2013-01-01

    This paper describes a stripping method for the determination of acyclovir at the submicromolar concentration level. This method is based on controlled adsorptive accumulation of acyclovir at thin-film mercury electrode, followed by a linear cyclic scan voltammetry measurement of the surface species. Optimal experimental conditions include a NaOH solution of 2.0 × 10−3 mol L−1 (supporting electrolyte), an accumulation potential of −0.40 V, and a scan rate of 100 mV s−1. The response of acyclovir is linear over the concentration range 0.02 to 0.12 ppm. For an accumulation time of 4 minutes, the detection limit was found to be 0.42 ppb (1.0 × 10−9 mol L−1). More convenient methods to measure the acyclovir in presence of the didanosine, efavirenz, nevirapine, nelfinavir, lamivudine, and zidovudine were also investigated. The utility of this method is demonstrated by the presence of acyclovir together with Adenosine triphosphate (ATP) or DNA. PMID:23761958

  13. The cyclic renewable mercury film silver based electrode for determination of molybdenum(VI) traces using adsorptive stripping voltammetry.

    PubMed

    Piech, Robert; Baś, Bogusław; Kubiak, Władysław W

    2008-07-15

    The new cyclic renewable mercury film silver based electrode (Hg(Ag)FE), applied for the determination of molybdenum(VI) traces using differential pulse adsorptive cathodic stripping voltammetry (DP AdSV) is presented. The Hg(Ag)FE electrode is characterized by very good surface reproducibility (

  14. Square wave adsorptive stripping voltammetry of molybdenum(VI) in continuous flow at a wall-jet mercury film electrode sensor.

    PubMed

    Neto, M M; Rocha, M M; Brett, C M

    1994-09-01

    An adsorptive stripping voltammetry method for the determination of traces of molybdenum(VI) in flowing solution at a wall-jet electrode sensor has been developed. After adsorption of a molybdenum complex on a wall-jet mercury film electrode, the complex is reduced by a square wave scan. More satisfactory results were obtained using 8-hydroxyquinoline as a complexing agent in nitrate medium than using Toluidine Blue in oxalic acid. Enhanced sensitivity was achieved by optimizing adsorption time and square wave parameter values. The detection limit of Mo(VI) was found to be at the nanomolar level. Interference of some other metallic species in the determination of nanomolar Mo(VI) was also investigated: Cu(II), Zn(II), Mn(II) do not interfere at 10 muM, whereas 1 muM FeEDTA(-) causes an increase in peak current. This iron interference was removed effectively with citric acid.

  15. Adsorption capacity of poly(ether imide) microparticles to uremic toxins.

    PubMed

    Tetali, Sarada D; Jankowski, Vera; Luetzow, Karola; Kratz, Karl; Lendlein, Andreas; Jankowski, Joachim

    2016-01-01

    Uremia is a phenomenon caused by retention of uremic toxins in the plasma due to functional impairment of kidneys in the elimination of urinary waste products. Uremia is presently treated by dialysis techniques like hemofiltration, dialysis or hemodiafiltration. However, these techniques in use are more favorable towards removing hydrophilic than hydrophobic uremic toxins. Hydrophobic uremic toxins, such as hydroxy hipuric acid (OH-HPA), phenylacetic acid (PAA), indoxyl sulfate (IDS) and p-cresylsulfate (pCRS), contribute substantially to the progression of chronic kidney disease (CKD) and cardiovascular disease. Therefore, objective of the present study is to test adsorption capacity of highly porous microparticles prepared from poly(ether imide) (PEI) as an alternative technique for the removal of uremic toxins. Two types of nanoporous, spherically shaped microparticles were prepared from PEI by a spraying/coagulation process.PEI particles were packed into a preparative HPLC column to which a mixture of the four types of uremic toxins was injected and eluted with ethanol. Eluted toxins were quantified by analytical HPLC. PEI particles were able to adsorb all four toxins, with the highest affinity for PAA and pCR. IDS and OH-HPA showed a partially non-reversible binding. In summary, PEI particles are interesting candidates to be explored for future application in CKD.

  16. Density functional investigation of mercury and arsenic adsorption on nitrogen doped graphene decorated with palladium clusters: A promising heavy metal sensing material in farmland

    NASA Astrophysics Data System (ADS)

    Zhao, Chunjiang; Wu, Huarui

    2017-03-01

    Density functional theory calculations are carried out to study the adsorption of mercury and arsenic on Pdn (n = 1-6) supported on pyridine-like nitrogen doped graphene (PNG). Owing to the promising sensitivity in trace amounts of atoms or molecules, PNG can be acted as micro-sensor for sensing heavy metals in agriculture soils. Through the analyses of structural and electronic properties of pristine PNG and Pd atom decorated PNG, we find that the most favorable adsorption site for Pd atom is the vacancy site. The analyses of structural and electronic properties reveal that the Pd atom or clusters can enhance the reactivity for Hg and AsH3 adsorption on PNG. The adsorption ability of Hg on Pdn decorated PNG is found to be related to the d-band center (εd) of the Pdn, in which the closer εd of Pdn to the Fermi level, the higher adsorption strength for Hg on Pdn decorated PNG. Moreover, the charge transfer between Pdn and arsenic may constitute arsenic adsorption on Pdn decorated PNG. Further design of highly efficient carbon based sorbents for heavy metals removal should be focused on tailoring εd of adsorbed metals.

  17. Effective mercury(II) bioremoval from aqueous solution, and its electrochemical determination.

    PubMed

    Balderas-Hernández, Patricia; Roa-Morales, Gabriela; Ramírez-Silva, María Teresa; Romero-Romo, Mario; Rodríguez-Sevilla, Erika; Esparza-Schulz, Juan Marcos; Juárez-Gómez, Jorge

    2017-01-01

    This work proposed mercury elimination using agricultural waste (Allium Cepa L.). The biomass removed 99.4% of mercury, following a pseudo-second order kinetics (r(2) = 0.9999). The Langmuir model was adequately fitted to the adsorption isotherm, thereby obtaining the maximum mercury adsorption capacity of 111.1 ± 0.3 mg g(-1). The biomass showed high density of strong mercury chelating groups, thus making it economically attractive. Also, the implementation of a mercury-selective electrode for continuous determination in real time is proposed; this electrode replaces techniques like atomic absorption spectroscopy, thus it can be applied to real time studies. This work therefore presents a new perspective for removing mercury(II) from contaminated water for environmental remediation.

  18. [Effect of KI modified clay on elemental mercury removal efficiency].

    PubMed

    Shen, Bo-Xiong; Chen, Jian-Hong; Cai, Ji; He, Chuan; Li, Zhuo

    2014-08-01

    Adsorption tests of elemental mercury were carried out by using KI modified clay (bentonite) in simulated flue gas under different conditions. Brunauer-Emett-Teller measurement (BET), Fourier Transform Infraredspectroscopy (FTIR) and Thermogravimetric Analysis (TGA) were used to analyze the physical and chemical properties of the materials. Compared with the original bentonite, Hg(0) removal efficiency and Hg(0) adsorption capacity were drastically improved by the KI treatment. The experiment results also indicated that temperature could enhance the property of Hg(0) adsorption. Chemical adsorption was the dominant part in the process of Hg(0) adsorption. O2 was a beneficial factor for Hg(0) adsorption. SO2 was found to have a slight promotional effect on Hg(0) adsorption. The existence of H2O exhibited a dramatic inhibitory effect on Hg(0) adsorption.

  19. Li atom adsorption on graphene with various defects for large-capacity Li ion batteries: First-principles calculations

    NASA Astrophysics Data System (ADS)

    Shiota, Kento; Kawai, Takazumi

    2017-06-01

    We investigated the fundamental properties of the interaction between a Li atom and a graphene surface with various defect structures by first-principles electronic state calculations to improve the capacity and charge rate of a graphitic anode for Li ion battery applications. The adsorption energy tends to decrease as the number of deficit carbon atoms at a neighboring defect increases even for adsorption at a hexagonal ring (HR) away from defects, although the interaction between a Li adatom and an HR is similar independent of the defect structure. The reason for the change in adsorption energy is the electronic charge transfer from the Li 2s-like state to the defect-induced state near the Fermi level. We also found that a Li atom diffuses through a V6 defect without a diffusion barrier practically.

  20. Effect of different carbon nanotubes on cadmium toxicity to Daphnia magna: The role of catalyst impurities and adsorption capacity.

    PubMed

    Wang, Xinghao; Qu, Ruijuan; Liu, Jiaoqin; Wei, Zhongbo; Wang, Liansheng; Yang, Shaogui; Huang, Qingguo; Wang, Zunyao

    2016-01-01

    Experiments were conducted to investigate the effect of four different carbon nanotubes single- and multi-walled carbon nanotubes (SWCNTs and MWCNTs) and hydroxylated and carboxylated multi-walled carbon nanotubes (OH-MWCNTs and COOH-MWCNTs) on Cd toxicity to the aquatic organism Daphnia magna. The acute toxicity results indicated that all CNTs could enhance the toxicity of Cd to D. magna. Furthermore, the filtrate toxicity and adsorption tests showed that the toxicity-increasing effect of SWCNTs and MWCNTs in the overall system was mainly caused by catalysts impurities from the pristine CNTs, whereas the greater adsorption of Cd onto OH-MWCNTs (30.52 mg/g) and COOH-MWCNTs (24.93 mg/g) was the key factor contributing to the enhanced toxicity. This result raised a concern that the metal catalyst impurities, adsorption capacities, and accumulation of waterborne CNTs were responsible for the toxicity of Cd to aquatic organism.

  1. Dye-adsorption capacity of high surface-area hydrogen titanate nanosheets processed via modified hydrothermal method.

    PubMed

    Padinhattayil, Hareesh; Augustine, Rimesh; Shukla, Satyajit

    2013-04-01

    High surface-area (380 m2 x g(-1)) hydrogen titanate nanosheets (HTNS) processed via the modified hydrothermal method have been utilized for the removal of methylene blue (MB) dye from an aqueous solution via the surface-adsorption process involving the electrostatic attraction mechanism. The HTNS have been characterized using the transmission electron microscope (TEM), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) specific surface-area measurement techniques. The amount of MB dye adsorbed on the surface of HTNS at equilibrium (q(e)) has been examined as a function of contact time, initial dye-concentration, and initial solution-pH. Within the investigated range of initial solution-pH (2.5-11), the MB dye adsorption on the surface of HTNS has been observed to follow the pseudo-second-order kinetics with the dye-adsorption capacity of 119 mg x g(-1) at the initial solution-pH of - 10. The adsorption equilibrium follows the Langmuir isotherm within the initial solution-pH range of 2.5-10. However, in a highly basic solution (initial solution-pH -11), the adsorption equilibrium has been observed to follow the Langmuir, Freundlich, and Dubinin-Kaganer-Radushkevich (DKR) models in the different ranges of initial MB dye concentration. The mere dependence on the DKR model has not been observed within the investigated range of initial solution-pH. The differences in the dye-adsorption characteristics and capacity of HTNS, compared with those of hydrogen titanate nanotubes, have been attributed to the difference in their specific surface-area. Irrespective of the morphology, the maximum coverage of MB dye on the surface of hydrogen titanate has been noted to be the same (52%).

  2. Effect of O2 pressure on the hydrothermal growth of CuO hierarchical microstructures: characterization and hydrogen adsorption capacity

    NASA Astrophysics Data System (ADS)

    Roble, M.; Diaz-Droguett, D.

    2017-08-01

    In the present study, the effect of injected O2 pressure to a hydrothermal reactor on the growth, morphology, structure and hydrogen adsorption properties of CuO hierarchical microstructures was investigated. The synthesis consisted of a simple one-step hydrothermal reaction using copper chloride and aqueous ammonia. Hydrothermal reactions were carried at 200 °C at reaction times of 1 and 12 h injecting at the beginning of the synthesis O2 pressures of 0, 30 or 60 bar. The samples were characterized by SEM and EDS for morphological and chemical information, XRD for determination of crystalline phases, lattice parameters and crystallinity grade using Rietveld refinement. Specific surface area was determined using BET method from nitrogen adsorption/desorption isotherm measurements. Hydrogen adsorption capacities at 20 °C were studied for key samples using the quartz crystal microbalance technique under gas exposure pressures between 3 and 100 Torr. It was found that the samples were of monoclinic CuO phase consisting mainly of sphere-like hierarchical microstructures of different average sizes assembled by sheets. The effect of the reactor pressure was mainly seen on average size of the CuO microstructures due to changes in the growth rate, specifically during the first stages of the hydrothermal reaction. Reactor pressure induced changes on the crystallinity of the samples were determined but no correlation was stated. Hydrogen adsorption capacities of studied samples measured at 100 Torr ranged from 0.27 to 0.6 wt%, indicating a good performance as compared with other reported values. Oxygen deficiency in CuO can influence on the hydrogen adsorption capacity.

  3. Characterization of the cation-binding capacity of a potassium-adsorption filter used in red blood cell transfusion.

    PubMed

    Suzuki, Takao; Muto, Shigeaki; Miyata, Yukio; Maeda, Takao; Odate, Takayuki; Shimanaka, Kimio; Kusano, Eiji

    2015-06-01

    A K(+) -adsorption filter was developed to exchange K(+) in the supernatant of stored irradiated red blood cells with Na(+) . To date, however, the filter's adsorption capacity for K(+) has not been fully evaluated. Therefore, we characterized the cation-binding capacity of this filter. Artificial solutions containing various cations were continuously passed through the filter in 30 mL of sodium polystyrene sulfonate at 10 mL/min using an infusion pump at room temperature. The cation concentrations were measured before and during filtration. When a single solution containing K(+) , Li(+) , H(+) , Mg(2+) , Ca(2+) , or Al(3+) was continuously passed through the filter, the filter adsorbed K(+) and the other cations in exchange for Na(+) in direct proportion to the valence number. The order of affinity for cation adsorption to the filter was Ca(2+) >Mg(2+) >K(+) >H(+) >Li(+) . In K(+) -saturated conditions, the filter also adsorbed Na(+) . After complete adsorption of these cations on the filter, their concentration in the effluent increased in a sigmoidal manner over time. Cations that were bound to the filter were released if a second cation was passed through the filter, despite the different affinities of the two cations. The ability of the filter to bind cations, especially K(+) , should be helpful when it is used for red blood cell transfusion at the bedside. The filter may also be useful to gain a better understanding of the pharmacological properties of sodium polystyrene sulfonate.

  4. Novel hollow microspheres of hierarchical zinc-aluminum layered double hydroxides and their enhanced adsorption capacity for phosphate in water.

    PubMed

    Zhou, Jiabin; Yang, Siliang; Yu, Jiaguo; Shu, Zhan

    2011-09-15

    Hollow microspheres of hierarchical Zn-Al layered double hydroxides (LDHs) were synthesized by a simple hydrothermal method using urea as precipitating agent. The morphology and microstructure of the as-prepared samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), nitrogen adsorption-desorption isotherms and fourier transform infrared (FTIR) spectroscopy. It was found that the morphology of hierarchical Zn-Al LDHs can be tuned from irregular platelets to hollow microspheres by simply varying concentrations of urea. The effects of initial phosphate concentration and contact time on phosphate adsorption using various Zn-Al LDHs and their calcined products (LDOs) were investigated from batch tests. Our results indicate that the equilibrium adsorption data were best fitted by Langmuir isothermal model, with the maximum adsorption capacity of 54.1-232 mg/g; adsorption kinetics follows the pseudo-second-order kinetic equation and intra-particle diffusion model. In addition, Zn-Al LDOs are shown to be effective adsorbents for removing phosphate from aqueous solutions due to their hierarchical porous structures and high specific surface areas. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Predicting CH4 adsorption capacity of microporous carbon using N2 isotherm and a new analytical model

    USGS Publications Warehouse

    Sun, Jielun; Chen, S.; Rostam-Abadi, M.; Rood, M.J.

    1998-01-01

    A new analytical pore size distribution (PSD) model was developed to predict CH4 adsorption (storage) capacity of microporous adsorbent carbon. The model is based on a 3-D adsorption isotherm equation, derived from statistical mechanical principles. Least squares error minimization is used to solve the PSD without any pre-assumed distribution function. In comparison with several well-accepted analytical methods from the literature, this 3-D model offers relatively realistic PSD description for select reference materials, including activated carbon fibers. N2 and CH4 adsorption data were correlated using the 3-D model for commercial carbons BPL and AX-21. Predicted CH4 adsorption isotherms, based on N2 adsorption at 77 K, were in reasonable agreement with the experimental CH4 isotherms. Modeling results indicate that not all the pores contribute the same percentage Vm/Vs for CH4 storage due to different adsorbed CH4 densities. Pores near 8-9 A?? shows higher Vm/Vs on the equivalent volume basis than does larger pores.

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

    SciTech Connect

    Gill, Gary A.; Kuo, Li-Jung; Strivens, Jonathan E.; Wood, Jordana R.; Schlafer, Nicholas J.; Janke, Christopher J.; Das, Sadananda; Mayes, Richard; Saito, Tomonori; Brown, Suree S.; Tsouris, Constantinos; Tsouris, Costas; Wai, Chien M.; Pan, Horng-Bin

    2016-09-29

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

  7. Adsorption of chromium(III), mercury(II) and lead(II) ions onto 4-aminoantipyrine immobilized bentonite.

    PubMed

    Wang, Qihui; Chang, Xijun; Li, Dandan; Hu, Zheng; Li, Ruijun; He, Qun

    2011-02-28

    In this work, the immobilization of 4-aminoantipyrine onto bentonite was carried out and it was then used to investigate the adsorption behavior of Cr(III), Hg(II) and Pb(II) ions from aqueous solutions. The separation and preconcentration conditions of analytes were investigated, including effects of pH, the shaking time, the sample flow rate and volume, the elution condition and the interfering ions. Under optimum pH value (pH 4.0), the maximum static adsorption capacity of the sorbent was found to be 38.8, 52.9 and 55.5 mg g(-1) for Cr(III), Hg(II) and Pb(II), respectively. 2.0 mL of 2% thiourea in 1.0 M HCl solution effectively eluted the adsorbed metal ions. The detection limit (3σ) of this method defined by IUPAC was found to be 0.12, 0.09 and 0.23 ng mL(-1) for Cr(III), Hg(II) and Pb(II), respectively. The relative standard deviation (RSD) was lower 3.0% (n=8). The developed method has been validated by analyzing certified reference materials and successfully applied to the determination of trace Cr(III), Hg(II) and Pb(II) in water samples with satisfactory results.

  8. Relationship between the adsorption capacity of pesticides by wood residues and the properties of woods and pesticides.

    PubMed

    Rodriguez-Cruz, Sonia; Andrades, Maria S; Sanchez-Camazano, Maria; Sanchez-Martin, Maria J

    2007-05-15

    With the aim to explore the potential use of wood residues in technologies aimed at preventing the pollution of soil and water, we studied the adsorption of four non-ionic pesticides (linuron, alachlor, metalaxyl, and chlorpyrifos) and two ionic pesticides (dicamba and paraquat) with a Kow range of -4.5 to 4.7 by nine types of wood with lignin content in the 18.2-26.9% range. The Freundlich Kf values were considered as indicators of the adsorption capacity. A statistical study was carried out using simple and multiple correlations to establish the degree to which the different parameters of the woods and of the pesticides were involved in adsorption. In the case of the non-ionic pesticides, positive and negative significant correlations were observed between Kf and the lignin (r = 0.73-0.83, p < 0.05-0.01), and soluble C contents of the woods (r = 0.66-0.84), p < 0.1-0.01). For dicamba, a correlation between Kf and pH (r = -0.66, p < 0.1) of the woods was found, while for paraquat, this was seen between Kf and the cation exchange capacity (r = 0.71, p < 0.1) of the woods. No significant correlation was observed between Kf and the total C content of the woods. A highly significant correlation between Kf and Kow values (r > or = 0.93, p < 0.01) was found in the adsorption of the pesticides by the woods (with the exception of paraquat) showing that this parameter is very important in this adsorption process. The determination coefficient of the multiple correlation between Kf and the parameters Kow, soluble C, and lignin contents accounts for nearly 100% of the variability in adsorption for non-ionic pesticides. Based on the results of our study and of those of the literature related to the adsorption of aromatic hydrocarbons, we used the Kow values to define a predictive model of adsorption of hydrophobic organic compounds in general by the woods.

  9. Method and apparatus for sampling atmospheric mercury

    DOEpatents

    Trujillo, Patricio E.; Campbell, Evan E.; Eutsler, Bernard C.

    1976-01-20

    A method of simultaneously sampling particulate mercury, organic mercurial vapors, and metallic mercury vapor in the working and occupational environment and determining the amount of mercury derived from each such source in the sampled air. A known volume of air is passed through a sampling tube containing a filter for particulate mercury collection, a first adsorber for the selective adsorption of organic mercurial vapors, and a second adsorber for the adsorption of metallic mercury vapor. Carbon black molecular sieves are particularly useful as the selective adsorber for organic mercurial vapors. The amount of mercury adsorbed or collected in each section of the sampling tube is readily quantitatively determined by flameless atomic absorption spectrophotometry.

  10. Molecular basis for the high CO2 adsorption capacity of chabazite zeolites.

    PubMed

    Pham, Trong D; Hudson, Matthew R; Brown, Craig M; Lobo, Raul F

    2014-11-01

    CO2 adsorption in Li-, Na-, K-CHA (Si/Al=6,=12), and silica chabazite zeolites was investigated by powder diffraction. Two CO2 adsorption sites were found in all chabazites with CO2 locating in the 8-membered ring (8MR) pore opening being the dominant site. Electric quadrupole-electric field gradient and dispersion interactions drive CO2 adsorption at the middle of the 8 MRs, while CO2 polarization due to interaction with cation sites controls the secondary CO2 site. In Si-CHA, adsorption is dominated by dispersion interactions with CO2 observed on the pore walls and in 8 MRs. CO2 adsorption complexes on dual cation sites were observed on K-CHA, important for K-CHA-6 samples due to a higher probability of two K(+) cations bridging CO2. Trends in isosteric heats of CO2 adsorption based on cation type and concentration can be correlated with adsorption sites and CO2 quantity. A decrease in the hardness of metal cations results in a decrease in the direct interaction of these cations with CO2. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Quantitative evaluation of the effect of moisture contents of coconut shell activated carbon used for respirators on adsorption capacity for organic vapors.

    PubMed

    Abiko, Hironobu; Furuse, Mitsuya; Takano, Tsuguo

    2010-01-01

    Activated carbon is an elemental material used for hygienic applications, particularly as an adsorbent for harmful gases and vapors. In Japanese industrial and occupational hygiene, activated carbon produced from coconut shell is a traditional and popular adsorbent material due to its excellent adsorption ability and cost advantage. In this research, in order to clarify the effect of the preliminary content of moisture on the adsorption capacity in detail, we prepared several coconut shell activated carbons which were preconditioned by equilibration with moisture at different relative humidities. We measured their adsorption capacities as breakthrough times for 6 kinds of organic vapor, and attempted to determine the relationships between the relative weight increase of water adsorption and the decrease of adsorption capacities of the activated carbon specimens for the organic vapors. The procedure of the quantitative evaluation of the effect of moisture and the results are useful for practical applications of activated carbon, particularly those used as adsorbents in workplaces.

  12. Adsorption of Pb(II) on mesoporous activated carbons fabricated from water hyacinth using H3PO4 activation: Adsorption capacity, kinetic and isotherm studies

    NASA Astrophysics Data System (ADS)

    Huang, Yang; Li, Shunxing; Chen, Jianhua; Zhang, Xueliang; Chen, Yiping

    2014-02-01

    Activated carbons with high mesoporosity and abundant oxygen-containing functional groups were prepared from water hyacinth using H3PO4 activation (WHAC) to eliminate Pb(II) in water. Characterizations of the WHAC were performed using Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The BET analysis showed that WHAC possesses a high mesoporosity (93.9%) with a BET surface area of 423.6 m2/g. The presence of oxygen-containing functional groups including hydroxyl, carbonyl, carboxyl and phosphate groups renders the WHAC a favorable adsorbent for Pb(II) with the maximum monolayer capacity (qm) 118.8 mg/g. The adsorption behavior follows pseudo-first order kinetic and Langmuir isotherm. The desorption study demonstrated that the WHAC could be readily regenerated using 0.1 M HCl (pH = 1.0). The desorbed WHAC could be reused at least six times without significant adsorption capacity reduction. The adsorption process was spontaneous and endothermic with ΔG (-0.27, -1.13, -3.02, -3.62, -5.54, and -9.31 kJ/mol) and ΔH (38.72 kJ/mol). Under the optimized conditions, a small amount of the adsorbent (1.0 g/L) could remove as much as 90.1% of Pb(II) (50 mg/L) in 20 min at pH 6.0 and temperature of 298 K. Therefore, the WHAC has a great potential to be an economical and efficient adsorbent in the treatment of lead-contaminated water.

  13. Development of novel activated carbon-based adsorbents for control of Mercury emissions from coal-fired power plants

    SciTech Connect

    Vidic, R.D.; Liu, W.; Brown, T. D., University of Pittsburgh

    1998-01-01

    The overall objective of this study is to evaluate pertinent design and operational parameters that would enable successful application of adsorption-based technologies for the reduction of mercury emissions from coal-fired power plants. The first part of the study will evaluate the most suitable impregnate for its ability to enhance the adsorptive capacity of activated carbon for mercury vapor under various process conditions. The second part of the study will evaluate the rate of mercury uptake (adsorption kinetics) by several impregnated activated carbons. Concerned with the ability of the adsorbed mercury to migrate back into the environment once saturated adsorbent is removed from the system, the study will also determine the fate of mercury adsorbed on these impregnated carbons.

  14. Development of dry control technology for emissions of mercury in flue gas

    SciTech Connect

    Huang, Hann S.; Wu, Jiann M.; Livengood, C.D.

    1995-06-01

    In flue gases from coal-combustion systems, mercury in either the elemental state or its chloride form (HgCl{sub 2}) can be predominant among all the possible mercury species present; this predominance largely depends on the chlorine-to-mercury ratio in the coal feeds. Conventional flue-gas cleanup technologies are moderately effective in controlling HgCl{sub 2} but are very poor at controlling elemental mercury. Experiments were conducted on the removal of elemental mercury vapor by means of a number of different types of sorbents, using a fixed-bed adsorption system. Of the four commercial activated carbons evaluated, the sulfur-treated carbon sample gives the best removal performance, with good mercury-sorption capacities. Promising removal results also have been obtained with low-cost minerals after chemical treatments. These inorganic sorbents could potentially be developed into a cost-effective alternative to activated carbons for mercury removal.

  15. High gas storage capacities and stepwise adsorption in a UiO type metal-organic framework incorporating Lewis basic bipyridyl sites.

    PubMed

    Li, Liangjun; Tang, Sifu; Wang, Chao; Lv, Xiaoxia; Jiang, Min; Wu, Huaizhi; Zhao, Xuebo

    2014-03-04

    A UiO type MOF with Lewis basic bipyridyl sites was synthesized and structurally characterized. After being activated by Soxhlet-extraction, this MOF exhibits high storage capacities for H2, CH4 and CO2, and shows unusual stepwise adsorption for liquid CO2 and solvents, indicating a sequential filling mechanism on different adsorption sites.

  16. Influence of surface oxidation of multiwalled carbon nanotubes on the adsorption affinity and capacity of polar and nonpolar organic compounds in aqueous phase.

    PubMed

    Wu, Wenhao; Chen, Wei; Lin, Daohui; Yang, Kun

    2012-05-15

    Adsorption of organic contaminants on carbon nanotubes (CNTs) is a critical behavior in the environmental application of CNTs as sorbents and in the environmental risk assessment of both organic contaminants and CNTs. Oxidation of CNTs may introduce oxygen-containing groups on CNTs' surface and then alter the adsorption of organic contaminants. In this study, adsorption of polar and nonpolar organic compounds on four multiwalled carbon nanotubes (MWCNTs) containing varied amounts of surface oxygen-containing groups were investigated to examine the influence of CNTs' surface oxidation on adsorption. We observed that surface oxidation of MWCNTs reduced the surface area-normalized adsorption capacity of organic compounds significantly because of the competition of water molecules but did not alter the adsorption affinity. The interactions (i.e., hydrophobic effect, π-π bonds, and hydrogen bonds) and the interaction strength for adsorption of organic molecules on MWCNTs could not be altered by the surface oxidation of MWCNTs and thus were responsible for the unaltered adsorption affinity. In addition, the decrease of surface area-normalized adsorption capacity of the organic compound with more polarity and higher adsorption affinity by surface oxidation was less because of the heterogeneous nature of hydrophilic sites of MWCNTs' surface.

  17. Simultaneous activation/sulfurization method for production of sulfurized activated carbons: characterization and Hg(II) adsorption capacity.

    PubMed

    Shamsijazeyi, Hadi; Kaghazchi, Tahereh

    2014-01-01

    As an inexpensive method for modification of activated carbons (ACs), sulfurization has attracted significant attention. However, the resulting sulfurized activated carbons (SACs) often are less porous than the original ACs. In this work, we propose a new method for concurrent sulfurization/activation that can lead to preparation of SACs with more porosity than the corresponding non-sulfurized ACs. By using scanning electron microscopy, nitrogen adsorption/desorption, and iodine number experiments, the porous structure of the SACs has been compared with that of non-sulfurized ACs. The specific surface areas of SACs are higher than the corresponding ACs, regardless of the type of activation agents used. For instance, the specific surface area of SAC and AC activated with phosphoric acid is 1,637 and 1,338 m(2)/g, respectively. Additionally, sulfur contents and surface charges (pHpzc) of the SACs and non-sulfurized ACs are compared. In fact, the SACs have higher sulfur contents and more acidic surfaces. Furthermore, the Hg(II) adsorption capacity of SACs has been compared with the corresponding non-sulfurized ACs. The Hg(II) adsorption isotherms on a selected SAC is measured at different pH values and temperatures. Hg(II) adsorptions as high as 293 mg/g are observed by using SACs prepared by the method proposed in this study.

  18. Effects of Igneous Intrusion on Microporosity and Gas Adsorption Capacity of Coals in the Haizi Mine, China

    PubMed Central

    2014-01-01

    This paper describes the effects of igneous intrusions on pore structure and adsorption capacity of the Permian coals in the Huaibei Coalfield, China. Twelve coal samples were obtained at different distances from a ~120 m extremely thick sill. Comparisons were made between unaltered and heat-affected coals using geochemical data, pore-fracture characteristics, and adsorption properties. Thermal alteration occurs down to ~1.3 × sill thickness. Approaching the sill, the vitrinite reflectance (Ro) increased from 2.30% to 2.78%, forming devolatilization vacuoles and a fine mosaic texture. Volatile matter (VM) decreased from 17.6% to 10.0% and the moisture decreased from 3.0% to 1.6%. With decreasing distance to the sill, the micropore volumes initially increased from 0.0054 cm3/g to a maximum of 0.0146 cm3/g and then decreased to 0.0079 cm3/g. The results show that the thermal evolution of the sill obviously changed the coal geochemistry and increased the micropore volume and adsorption capacity of heat-affected coal (60–160 m from the sill) compared with the unaltered coals. The trap effect of the sill prevented the high-pressure gas from being released, forming gas pocket. Mining activities near the sill created a low pressure zone leading to the rapid accumulation of methane and gas outbursts in the Haizi Mine. PMID:24723841

  19. Functionalized graphene sheets with poly(ionic liquid)s and high adsorption capacity of anionic dyes

    NASA Astrophysics Data System (ADS)

    Zhao, Weifeng; Tang, Yusheng; Xi, Jia; Kong, Jie

    2015-01-01

    Graphene sheets were covalently functionalized with poly(1-vinylimidazole) (PVI) type poly(ionic liquid), by utilizing a diazonium addition reaction and the subsequent grafting of PVI polymers onto the graphene sheet surface by a quaternarization reaction. The resultant modified graphene sheets showed improved dispersion property when being dissolved in DMF and ethanol. FTIR, XPS, XRD and TEM observations confirmed the success of the covalent functionalization, and thermogravimetric analysis revealed that the grafting ratio of PVI was ∼12 wt%. The obtained PVI-functionalized graphene showed a high capability for removing anionic dyes such as methyl blue (MB) from water solution. The experimental data of isotherm fitted well with the Langmuir adsorption model. The adsorption capacity of 1910 mg g-1 for methyl blue (MB) dye was observed for functionalized graphene sheets with poly(ionic liquid)s, which was higher than that of unmodified graphene. The high adsorption capacity observed in this study emphasizes that poly(ionic liquid)s-modified graphene materials have a great potential for water purification as they are highly efficient and stable adsorbents for sustainability.

  20. Effects of igneous intrusion on microporosity and gas adsorption capacity of coals in the Haizi Mine, China.

    PubMed

    Jiang, Jingyu; Cheng, Yuanping

    2014-01-01

    This paper describes the effects of igneous intrusions on pore structure and adsorption capacity of the Permian coals in the Huaibei Coalfield, China. Twelve coal samples were obtained at different distances from a ~120 m extremely thick sill. Comparisons were made between unaltered and heat-affected coals using geochemical data, pore-fracture characteristics, and adsorption properties. Thermal alteration occurs down to ~1.3 × sill thickness. Approaching the sill, the vitrinite reflectance (R(o)) increased from 2.30% to 2.78%, forming devolatilization vacuoles and a fine mosaic texture. Volatile matter (VM) decreased from 17.6% to 10.0% and the moisture decreased from 3.0% to 1.6%. With decreasing distance to the sill, the micropore volumes initially increased from 0.0054 cm(3)/g to a maximum of 0.0146 cm(3)/g and then decreased to 0.0079 cm(3)/g. The results show that the thermal evolution of the sill obviously changed the coal geochemistry and increased the micropore volume and adsorption capacity of heat-affected coal (60-160 m from the sill) compared with the unaltered coals. The trap effect of the sill prevented the high-pressure gas from being released, forming gas pocket. Mining activities near the sill created a low pressure zone leading to the rapid accumulation of methane and gas outbursts in the Haizi Mine.

  1. KINETIC STUDY OF ADSORPTION AND TRANSFORMATION OF MERCURY ON FLY ASH PARTICLES IN AN ENTRAINED FLOW REACTOR

    EPA Science Inventory

    Experimental studies were performed to investigate the interactions of elemental mercury vapor with entrained fly ash particles from coal combustion in a flow reactor. The rate of transformation of elemental mercury on fly ash particles was evauated over the temperature range fro...

  2. KINETIC STUDY OF ADSORPTION AND TRANSFORMATION OF MERCURY ON FLY ASH PARTICLES IN AN ENTRAINED FLOW REACTOR

    EPA Science Inventory

    Experimental studies were performed to investigate the interactions of elemental mercury vapor with entrained fly ash particles from coal combustion in a flow reactor. The rate of transformation of elemental mercury on fly ash particles was evauated over the temperature range fro...

  3. Effect of the concentration of inherent mineral elements on the adsorption capacity of coconut shell-based activated carbons.

    PubMed

    Afrane, G; Achaw, Osei-Wusu

    2008-09-01

    Coconut shells of West Africa Tall, a local variety of the coconut species Cocos nucifera L., were taken from five different geographical locations in Ghana and examined for the presence and concentration levels of some selected mineral elements using atomic absorption spectrometer. Activated carbons were subsequently made from the shells by the physical method. The iodine adsorption characteristics of the activated carbons measured showed a definite relationship to the concentration levels of potassium and other mineral elements in the precursor shell. Samples with lower total minerals content recorded higher iodine numbers. It was observed that the origin of the shells was related to the concentration levels of the analyzed mineral elements in the shells, which in turn affected the adsorption capacity of the activated carbons. The results of this study have important implications for the sourcing of coconuts whose shells are used in the manufacture of activated carbons.

  4. Effect of heat on the adsorption capacity of an activated carbon for decolorizing/deodorizing yellow zein.

    PubMed

    Sessa, D J; Palmquist, D E

    2008-09-01

    The Freundlich model was evaluated for use to assess the effect of heat on the adsorption capacity of an activated carbon for decolorizing/deodorizing corn zein. Because zein protein and its color/odor components are all adsorbed by activated carbon, a method to monitor their removal was needed. Yellow color is due to xanthophylls; a contributor to off-odor is diferuloylputrescine. The off-odor component absorbs ultraviolet (UV) light at about 325 nm and its removal coincides with removal of yellow color. A spectrophotometric method based on UV absorbances 280 nm for protein and 325 nm for the off-odor component was used to monitor their adsorptions onto activated carbon. Equilibrium studies were performed over temperature range from 25 to 60 degrees C for zein dissolved in 70% aqueous ethanol. Runs made at 55 degrees C adsorbed significantly more of the color/odor components than the protein.

  5. Fate and aqueous transport of mercury in light of the Clean Air Mercury Rule for coal-fired electric power plants

    NASA Astrophysics Data System (ADS)

    Arzuman, Anry

    Mercury is a hazardous air pollutant emitted to the atmosphere in large amounts. Mercury emissions from electric power generation sources were estimated to be 48 metric tons/year, constituting the single largest anthropogenic source of mercury in the U.S. Settled mercury species are highly toxic contaminants of the environment. The newly issued Federal Clean Air Mercury Rule requires that the electric power plants firing coal meet the new Maximum Achievable Mercury Control Technology limit by 2018. This signifies that all of the air-phase mercury will be concentrated in solid phase which, based on the current state of the Air Pollution Control Technology, will be fly ash. Fly ash is utilized by different industries including construction industry in concrete, its products, road bases, structural fills, monifills, for solidification, stabilization, etc. Since the increase in coal combustion in the U.S. (1.6 percent/year) is much higher than the fly ash demand, large amounts of fly ash containing mercury and other trace elements are expected to accumulate in the next decades. The amount of mercury transferred from one phase to another is not a linear function of coal combustion or ash production, depends on the future states of technology, and is unknown. The amount of aqueous mercury as a function of the future removal, mercury speciation, and coal and aquifer characteristics is also unknown. This paper makes a first attempt to relate mercury concentrations in coal, flue gas, fly ash, and fly ash leachate using a single algorithm. Mercury concentrations in all phases were examined and phase transformation algorithms were derived in a form suitable for probabilistic analyses. Such important parameters used in the transformation algorithms as Soil Cation Exchange Capacity for mercury, soil mercury selectivity sequence, mercury activity coefficient, mercury retardation factor, mercury species soil adsorption ratio, and mercury Freundlich soil adsorption isotherm

  6. Separation of mercury from aqueous mercuric chloride solutions by onion skins

    SciTech Connect

    Asai, S.; Konishi, Y.; Tomisaki, H.; Nakanishi, M.

    1986-01-01

    The separation of mercury from aqueous HgCl/sub 2/ solutions by onion skins (outermost coat) was studied both experimentally and theoretically. The distribution equilibria were measured by the batchwise method. The experimental results revealed that onion skin is a useful material for separating mercury from aqueous systems. The distribution data obtained at 25/sup 0/C were analyzed by using the theory based on the law of mass action. The separation of dissolved mercury by onion skins was found to be a process accompanied by an ion-exchange reaction of the cationic complex HgCl/sup +/ and an adsorption of the neutral complex HgCl/sub 2/. The equilibrium constants of the ion-exchange and adsorption processes at 25/sup 0/C and the mercury-binding capacity of onion skins were determined. Further, it was found that the distribution equilibrium of mercury is comparatively insensitive to temperature.

  7. 2,4-D adsorption to biochars: effect of preparation conditions on equilibrium adsorption capacity and comparison with commercial activated carbon literature data.

    PubMed

    Kearns, J P; Wellborn, L S; Summers, R S; Knappe, D R U

    2014-10-01

    Batch isotherm experiments were conducted with chars to study adsorption of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Chars generated from corncobs, bamboo and wood chips in a laboratory pyrolyzer at 400-700 °C were compared with traditional kiln charcoals collected from villages in S/SE Asia and with activated carbons (ACs). 2,4-D uptake by laboratory chars obtained from bamboo and wood chips after 14 h of pyrolysis at 700 °C, from wood chips after 96 h of pyrolysis at 600 °C, and one of the field-collected chars (basudha) was comparable to ACs. H:C and O:C ratios declined with pyrolysis temperature and duration while surface area increased to >500 m(2)/g. Increasing pyrolysis intensity by increasing temperature and/or duration of heating was found to positively influence adsorption capacity yield (mg(2,4-D/g(feedstock))) over the range of conditions studied. Economic analysis showed that high temperature chars can be a cost-effective alternative to ACs for water treatment applications.

  8. Preparation of porous diatomite-templated carbons with large adsorption capacity and mesoporous zeolite K-H as a byproduct.

    PubMed

    Liu, Dong; Yuan, Weiwei; Deng, Liangliang; Yu, Wenbin; Sun, Hongjuan; Yuan, Peng

    2014-06-15

    In this study, KOH activation was performed to enhance the porosity of the diatomite-templated carbon and to increase its adsorption capacity of methylene blue (MB). In addition to serving as the activation agent, KOH was also used as the etchant to remove the diatomite templates. Zeolite K-H was synthesized as a byproduct via utilization of the resultant silicon- and potassium-containing solutions created from the KOH etching of the diatomite templates. The obtained diatomite-based carbons were composed of macroporous carbon pillars and tubes, which were derived from the replication of the diatomite templates and were well preserved after KOH activation. The abundant micropores in the walls of the carbon pillars and tubes were derived from the break and reconfiguration of carbon films during both the removal of the diatomite templates and KOH activation. Compared with the original diatomite-templated carbons and CO2-activated carbons, the KOH-activated carbons had much higher specific surface areas (988 m(2)/g) and pore volumes (0.675 cm(3)/g). Moreover, the KOH-activated carbons possessed larger MB adsorption capacity (the maximum Langmuir adsorption capacity: 645.2 mg/g) than those of the original carbons and CO2-activated carbons. These results showed that KOH activation was a high effective activation method. The zeolite K-H byproduct was obtained by utilizing the silicon- and potassium-containing solution as the silicon and potassium sources. The zeolite exhibited a stick-like morphology and possessed nanosized particles with a mesopore-predominant porous structure which was observed by TEM for the first time. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. PREDICTING THE ADSORPTION CAPACITY OF ACTIVATED CARBON FOR ORGANIC CONTAMINANTS FROM ADSORBENT AND ADSORBATE PROPERTIES

    EPA Science Inventory

    A quantitative structure-property relationship (QSPR) was developed and combined with the Polanyi-Dubinin-Manes model to predict adsorption isotherms of emerging contaminants on activated carbons with a wide range of physico-chemical properties. Affinity coefficients (βl

  10. PREDICTING THE ADSORPTION CAPACITY OF ACTIVATED CARBON FOR ORGANIC CONTAMINANTS FROM ADSORBENT AND ADSORBATE PROPERTIES

    EPA Science Inventory

    A quantitative structure-property relationship (QSPR) was developed and combined with the Polanyi-Dubinin-Manes model to predict adsorption isotherms of emerging contaminants on activated carbons with a wide range of physico-chemical properties. Affinity coefficients (βl

  11. Properties of poly(1-naphthylamine)/Fe3O4 composites and arsenic adsorption capacity in wastewater

    NASA Astrophysics Data System (ADS)

    Tran, Minh Thi; Nguyen, Thi Huyen Trang; Vu, Quoc Trung; Nguyen, Minh Vuong

    2016-03-01

    The research results of poly(1-naphthylamine)/Fe3O4 (PNA/Fe3O4) nanocomposites synthesized by a chemical method for As(III) wastewater treatment are presented in this paper. XRD patterns and TEM images showed that the Fe3O4 grain size varied from 13 to 20 nm. The results of Raman spectral analysis showed that PNA participated in part of the PNA/Fe3O4 composite samples. The grain size of PNA/Fe3O4 composite samples is about 25-30 nm measured by SEM. The results of vibrating sample magnetometer measurements at room temperature showed that the saturation magnetic moment of PNA/Fe3O4 samples decreased from 63.13 to 43.43 emu/g, while the PNA concentration increased from 5% to 15%. The nitrogen adsorption-desorption isotherm of samples at 77 K at a relative pressure P/ P 0 of about 1 was studied in order to investigate the surface and porous structure of nanoparticles by the BET method. Although the saturation magnetic moments of samples decreased with the polymer concentration increase, the arsenic adsorption capacity of the PNA/Fe3O4 sample with the PNA concentration of 5% is better than that of Fe3O4 in a solution with pH = 7. In the solution with pH > 14, the arsenic adsorption of magnetic nanoparticles is insignificant.

  12. Hyperbranched-polyol-tethered poly (amic acid) electrospun nanofiber membrane with ultrahigh adsorption capacity for boron removal

    NASA Astrophysics Data System (ADS)

    Wang, Zhe; Wu, Zhongyu; Zhang, Yufeng; Meng, Jianqiang

    2017-04-01

    The development of efficient adsorbents with high sorption capacity remains as a challenge for the removal of micropollutants occurred globally in water resources. In this work, poly (amic acid) (PAA) electrospun nanofiber membranes grafted with hyperbranched polyols were synthesized and used for boron removal. The PAA nanofiber was reacted with hyperbranched polyethylenimine (HPEI) and further with glycidol to introduce the vicinal hydroxyl groups. The chemical composition and surface characteristics of the obtained PAA-g-PG membranes were evaluated by FESEM, FTIR, XPS and water contact angles (WCA) measurements. The boron adsorption thermodynamics and kinetics were investigated systematically. The results showed that the PAA nanofiber spun from concentration of 15% had uniform morphology and narrow diameter distribution. The PAA-g-PG nanofiber membrane had a maximum boron uptake of 5.68 mmol/g and could adsorb 0.82 mmol/g boron from a 5 mg/L solution in 15 min. Both the high surface area of nanofibers and the hyperbranched structure should contribute to the high boron uptake and high adsorption rate. The nanofiber membrane obeyed the Langmuir adsorption model and the pseudo-first-order kinetic model. The regeneration efficiency of the nanofiber membrane remained 93.9% after 10 cycled uses, indicating good regenerability of the membrane.

  13. Biochar characteristics produced from food-processing products and their sorptive capacity for mercury and phenanthrene

    NASA Astrophysics Data System (ADS)

    Fotopoulou, Kalliopi N.; Karapanagioti, Hrissi K.; Manariotis, Ioannis D.

    2015-04-01

    Various organic-rich wastes including wood chips, animal manure, and crop residues have been used for biochar production. Biochar is used as an additive to soils to sequester carbon and improve soil fertility but its use as a sorbent for environmental remediation processes is gaining increased attention. Surface properties such as point of zero charge, surface area and pore volume, surface topography, surface functional groups and acid-base behavior are important factors, which affect sorption efficiency. Understanding the surface alteration of biochars increases our understanding of the pollutant-sorbent interaction. The scope of the present work was to evaluate the effect of key characteristics of biochars on their sorptive properties. Raw materials for biochar production were evaluated including byproducts from brewering, coffee, wine, and olive oil industry. The charring process was performed at different temperatures under limited-oxygen conditions using specialized containers. The surface area, the pore volume, and the average pore size of the biochars were determined. Open surface area and micropore volume were determined using t-plot method and Harkins & Jura equation. Raw food-processing waste demonstrates low surface area that increases by 1 order of magnitude by thermal treatment up to 750oC. At temperatures from 750 up to 900oC, pyrolysis results to biochars with surface areas 210-700 m2/g. For the same temperature range, a high percentage (46 to73%) of the pore volume of the biochars is due to micropores. Positive results were obtained when high surface area biochars were tested for their ability to remove organic (i.e. phenanthrene) and inorganic (i.e. mercury) compounds from aqueous solutions. All these properties point to new materials that can effectively be used for environmental remediation.

  14. Synthesis, characterisation and methyl orange adsorption capacity of ferric oxide-biochar nano-composites derived from pulp and paper sludge

    NASA Astrophysics Data System (ADS)

    Chaukura, Nhamo; Murimba, Edna C.; Gwenzi, Willis

    2017-09-01

    A Fe2O3-biochar nano-composite (Fe2O3-BC) was prepared from FeCl3-impregnated pulp and paper sludge (PPS) by pyrolysis at 750 °C. The characteristics and methyl orange (MO) adsorption capacity of Fe2O3-BC were compared to that of unactivated biochar (BC). X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the composite material was nano-sized. Fourier transform infrared (FTIR) spectroscopy revealed the presence of hydroxyl and aromatic groups on BC and on Fe2O3-BC, but Brunauer-Emmett-Teller (BET) surface area and Barrett-Joyner-Halenda (BJH) porosity were lower for Fe2O3-BC than BC. Despite the lower BET surface area and porosity of Fe2O3-BC, its MO adsorption capacity was 52.79 % higher than that of BC. The equilibrium adsorption data were best represented by the Freundlich model with a maximum adsorption capacity of 20.53 mg g-1 at pH 8 and 30 min contact time. MO adsorption obeyed pseudo-second-order kinetics for both BC and Fe2O3-BC with R 2 values of 0.996 and 0.999, respectively. Higher MO adsorption capacity for Fe2O3-BC was attributed to the hybrid nature of the nano-composites; adsorption occurred on both biochar matrix and Fe2O3 nanocrystals. Gibbs free energy calculations confirmed the adsorption is energetically favourable and spontaneous with a high preference for adsorption on both adsorbents. The nano-composite can be used for the efficient removal of MO (>97 %) from contaminated wastewater.

  15. Synthesis, characterisation and methyl orange adsorption capacity of ferric oxide-biochar nano-composites derived from pulp and paper sludge

    NASA Astrophysics Data System (ADS)

    Chaukura, Nhamo; Murimba, Edna C.; Gwenzi, Willis

    2016-02-01

    A Fe2O3-biochar nano-composite (Fe2O3-BC) was prepared from FeCl3-impregnated pulp and paper sludge (PPS) by pyrolysis at 750 °C. The characteristics and methyl orange (MO) adsorption capacity of Fe2O3-BC were compared to that of unactivated biochar (BC). X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the composite material was nano-sized. Fourier transform infrared (FTIR) spectroscopy revealed the presence of hydroxyl and aromatic groups on BC and on Fe2O3-BC, but Brunauer-Emmett-Teller (BET) surface area and Barrett-Joyner-Halenda (BJH) porosity were lower for Fe2O3-BC than BC. Despite the lower BET surface area and porosity of Fe2O3-BC, its MO adsorption capacity was 52.79 % higher than that of BC. The equilibrium adsorption data were best represented by the Freundlich model with a maximum adsorption capacity of 20.53 mg g-1 at pH 8 and 30 min contact time. MO adsorption obeyed pseudo-second-order kinetics for both BC and Fe2O3-BC with R 2 values of 0.996 and 0.999, respectively. Higher MO adsorption capacity for Fe2O3-BC was attributed to the hybrid nature of the nano-composites; adsorption occurred on both biochar matrix and Fe2O3 nanocrystals. Gibbs free energy calculations confirmed the adsorption is energetically favourable and spontaneous with a high preference for adsorption on both adsorbents. The nano-composite can be used for the efficient removal of MO (>97 %) from contaminated wastewater.

  16. Evaluation of phosphorus adsorption capacity of sesame straw biochar on aqueous solution: influence of activation methods and pyrolysis temperatures.

    PubMed

    Park, J H; Ok, Y S; Kim, S H; Cho, J S; Heo, J S; Delaune, R D; Seo, D C

    2015-12-01

    The phosphorus (P) adsorption characteristic of sesame straw biochar prepared with different activation agents and pyrolysis temperatures was evaluated. Between 0.109 and 0.300 mg L(-1) in the form of inorganic phosphate was released from raw sesame straw biochar in the first 1 h. The release of phosphate was significantly enhanced from 62.6 to 168.2 mg g(-1) as the pyrolysis temperature increased. Therefore, sesame straw biochar cannot be used as an adsorbent for P removal without change in the physicochemical characteristics. To increase the P adsorption of biochar in aqueous solution, various activation agents and pyrolysis temperatures were applied. The amount of P adsorbed from aqueous solution by biochar activated using different activation agents appeared in the order ZnCl2 (9.675 mg g(-1)) > MgO (8.669 mg g(-1)) ⋙ 0.1N-HCl > 0.1N-H2SO4 > K2SO4 ≥ KOH ≥ 0.1N-H3PO4, showing ZnCl2 to be the optimum activation agent. Higher P was adsorbed by the biochar activated using ZnCl2 under different pyrolysis temperatures in the order 600 °C > 500 °C > 400 °C > 300 °C. Finally, the amount of adsorbed P by activated biochar at different ratios of biochar to ZnCl2 appeared in the order 1:3 ≒ 1:1 > 3:1. As a result, the optimum ratio of biochar to ZnCl2 and pyrolysis temperature were found to be 1:1 and 600 °C for P adsorption, respectively. The maximum P adsorption capacity by activated biochar using ZnCl2 (15,460 mg kg(-1)) was higher than that of typical biochar, as determined by the Langmuir adsorption isotherm. Therefore, the ZnCl2 activation of sesame straw biochar was suitable for the preparation of activated biochar for P adsorption.

  17. Removal of mercury species with dithiocarbamate-anchored polymer/organosmectite composites.

    PubMed

    Say, Ridvan; Birlik, Ebru; Erdemgil, Zerrin; Denizli, Adil; Ersöz, Arzu

    2008-02-11

    Mercury is one of the most toxic heavy metals found in solid and liquid waste disposed by chloro-alkali, paint, paper/pulp, battery, pharmaceutical, oil refinery and mining companies. Any form of mercury introduced to nature through any means is converted into a more toxic form such as methylmercury chloride (as produced by aquatic organisms) which usually accumulates in the tissue of fish and birds. The primary aim of this study was to investigate performance of dithiocarbamate-anchored polymer/organosmectite composites as sorbents for removal of mercury from aqueous solution. The modified smectite nanocomposites then were reacted with carbondisulfide to incorporate dithiocarbamate functional groups into the nanolayer of the organoclay. These dithiocarbamate-anchored composites were used for the removal of mercury species [Hg(II), CH(3)Hg(I) and C(6)H(5)Hg(I)]. Mercury adsorption was found to be dependent on the solution pH, mercury concentration and the type of mercury species to be adsorbed. The maximum adsorption capacities were equal to 157.3 mg g(-1) (782.5 micromol g(-1)) for Hg(II); 214.6 mg g(-1) (993.9 micromol g(-1)) for CH(3)Hg(I); 90.3 mg g(-1) (325 micromol g(-1)) for C(6)H(5)Hg(I). The competitive adsorption capacities (i.e. adsorption capacities based on solutions containing all three mercuric ions) are 7.7 mg g(-l) (38.3 micromol g(-1)), 9.2 mg g(-l) (42.6 micromol g(-1)) and 12.7 mg g(-1) (45.7 micromol g(-1)) for Hg(II), CH(3)Hg(I) and C(6)H(5)Hg(I), respectively, at 10 ppm initial concentration. The adsorption capacities on molar basis were in order of C(6)H(5)Hg(I)>CH(3)Hg(I)>Hg(II).

  18. Synthesis of bilayer MoS{sub 2} nanosheets by a facile hydrothermal method and their methyl orange adsorption capacity

    SciTech Connect

    Ye, Lijuan; Xu, Haiyan; Zhang, Dingke; Chen, Shijian

    2014-07-01

    Highlights: • Hexagonal phase of MoS{sub 2} nanosheets was synthesized by a facile hydrothermal method. • FE-SEM and TEM images show the sheets-like morphology of MoS{sub 2}. • Bilayer MoS{sub 2} can be grown under the optimized mole ratio of 2:1 of S:Mo at 180 °C for 50 h. • The MoS{sub 2} nanosheets possess high methyl orange adsorption capacity due to the large surface area. - Abstract: Molybdenum disulfide (MoS{sub 2}) nanosheets have received significant attention recently due to the potential applications for exciting physics and technology. Here we show that MoS{sub 2} nanosheets can be prepared by a facile hydrothermal method. The study of the properties of the MoS{sub 2} nanosheets prepared at different conditions suggests that the mole ratio of precursors and hydrothermal time significantly influences the purity, crystalline quality and thermal stability of MoS{sub 2}. X-ray diffraction, Raman spectra and transmission electron microscopy results indicate that bilayer MoS{sub 2} can be grown under an optimized mole ratio of 2:1 of S:Mo at 180 °C for 50 h. Moreover, such ultrathin nanosheets exhibit a prominent photoluminescence and possess high methyl orange adsorption capacity due to the large surface area, which can be potentially used in photodevice and photochemical catalyst.

  19. Preparation and evaluation adsorption capacity of cellulose xanthate of sugarcane bagasse for removal heavy metal ion from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Iryani, D. A.; Risthy, N. M.; Resagian, D. A.; Yuwono, S. D.; Hasanudin, U.

    2017-05-01

    The discharge of heavy metals from industrial effluents into aquatic system in surrounding area of Lampung bay become a serious problem today. The data shows that the concentrations of heavy metals in this area are above allowable limits for the discharge of toxic heavy metals in the aquatic systems. The most common of heavy metal pollutant is divalent metal ions. Cellulose xanthate is one of the selective adsorbent to solve this problem, since xanthate contains two negative sulfur atoms that is capable to catch divalent metal ions. Preparation of cellulose xanthate was conducted by reacting carbon disulfide (CS2) and cellulose from sugarcane bagasse. The morphological characteristics of cellulose xanthate were visualized via Scanning Electron Microscope (SEM) and the presence of sulfur groups on sugarcane bagasse xanthate were identified by FTIR spectroscopic study. The degree of substitution (DS), degree of polymerization (DP), and adsorption capacities of cellulose xanthate for Cu2+ and Pb2+ metal were studied. The results of study reveals that the maximum adsorption capacities of Cu2+ and Pb2+ metal on cellulose xanthate are 54.226 mg Cu2+/g, and 51.776 mg Pb2+/g, respectively. This study reveals that cellulose xanthate could be a solution to reduce environmental pollution caused by industrial wastewater.

  20. Enhancing phosphate adsorption capacity of SDS-based magnetite by surface modification of citric acid

    NASA Astrophysics Data System (ADS)

    Yu, Zhigang; Zhang, Chang; Zheng, Zuhong; Hu, Liang; Li, Xuemei; Yang, Zhongzhu; Ma, Chi; Zeng, Guangming

    2017-05-01

    In this study, citric acid (CA) was employed as a low-molecule organic acid to influence the adsorption performance of phosphorus by as-obtained magnetite. The factors including initial phosphate concentrations, dosage of citric acid, pH value, ion strength, contact time and temperature were examined in detail. Results indicated that the dissolution of anion sodium dodecyl sulfate (SDS) covering on surface of magnetite, a slight decrease of Fe level and a superior structure of magnetite after CA modification occurred. The pH-dependence of phosphate adsorption was impeded and the surface potential of magnetite positively increased at pH > 5.0 when CA was added. Non-linear regression Langmuir-Freundlich model was fitted well in thermodynamics, and the opposite adsorption process as a function of temperatures with or without CA addition was due to the decrease of active energy and active mobility of phosphate ion. Finally, the declining adsorption efficiency with increasing cycles was observed while phosphate removal was approximately finished and had small change with 0.05 and 0.1 M of CA addition. Those improvements of removal efficiency of phosphorus by modified iron oxide were because of the removal of anionic SDS that increased the surface positive charge, and especially the dissolution of element Fe into solution to form precipitate with phosphorus ions. The enhanced stability of magnetite by CA also promoted the high removal efficiency of phosphorus. These implications of CA on phosphate removal can be extended to the field where phosphate pollution is notorious but urgent.

  1. Zeolite Y Adsorbents with High Vapor Uptake Capacity and Robust Cycling Stability for Potential Applications in Advanced Adsorption Heat Pumps.

    PubMed

    Li, Xiansen; Narayanan, Shankar; Michaelis, Vladimir K; Ong, Ta-Chung; Keeler, Eric G; Kim, Hyunho; McKay, Ian S; Griffin, Robert G; Wang, Evelyn N

    2015-01-01

    Modular and compact adsorption heat pumps (AHPs) promise an energy-efficient alternative to conventional vapor compression based heating, ventilation and air conditioning systems. A key element in the advancement of AHPs is the development of adsorbents with high uptake capacity, fast intracrystalline diffusivity and durable hydrothermal stability. Herein, the ion exchange of NaY zeolites with ingoing Mg(2+) ions is systematically studied to maximize the ion exchange degree (IED) for improved sorption performance. It is found that beyond an ion exchange threshold of 64.1%, deeper ion exchange does not benefit water uptake capacity or characteristic adsorption energy, but does enhance the vapor diffusivity. In addition to using water as an adsorbate, the uptake properties of Mg,Na-Y zeolites were investigated using 20 wt.% MeOH aqueous solution as a novel anti-freeze adsorbate, revealing that the MeOH additive has an insignificant influence on the overall sorption performance. We also demonstrated that the labscale synthetic scalability is robust, and that the tailored zeolites scarcely suffer from hydrothermal stability even after successive 108-fold adsorption/desorption cycles. The samples were analyzed using N2 sorption, (27)Al/(29)Si MAS NMR spectroscopy, ICP-AES, dynamic vapor sorption, SEM, Fick's 2(nd) law and D-R equation regressions. Among these, close examination of sorption isotherms for H2O and N2 adsorbates allows us to decouple and extract some insightful information underlying the complex water uptake phenomena. This work shows the promising performance of our modified zeolites that can be integrated into various AHP designs for buildings, electronics, and transportation applications.

  2. Zeolite Y adsorbents with high vapor uptake capacity and robust cycling stability for potential applications in advanced adsorption heat pumps

    SciTech Connect

    Li, XS; Narayanan, S; Michaelis, VK; Ong, TC; Keeler, EG; Kim, H; Mckay, IS; Griffin, RG; Wang, EN

    2015-01-01

    Modular and compact adsorption heat pumps (AHPs) promise an energy-efficient alternative to conventional vapor compression based heating, ventilation and air conditioning systems. A key element in the advancement of AHPs is the development of adsorbents with high uptake capacity, fast intracrystalline diffusivity and durable hydrothermal stability. Herein, the ion exchange of NaY zeolites with ingoing Mg2+ ions is systematically studied to maximize the ion exchange degree (IED) for improved sorption performance. It is found that beyond an ion exchange threshold of 64.1%, deeper ion exchange does not benefit water uptake capacity or characteristic adsorption energy, but does enhance the vapor diffusivity. In addition to using water as an adsorbate, the uptake properties of Mg, Na-Y zeolites were investigated using 20 wt.% MeOH aqueous solution as a novel anti-freeze adsorbate, revealing that the MeOH additive has an insignificant influence on the overall sorption performance. We also demonstrated that the lab-scale synthetic scalability is robust, and that the tailored zeolites scarcely suffer from hydrothermal stability even after successive 108-fold adsorption/desorption cycles. The samples were analyzed using N-2 sorption, Al-27/Si-29 MAS NMR spectroscopy, ICP-AES, dynamic vapor sorption, SEM, Fick's 2nd law and D-R equation regressions. Among these, close examination of sorption isotherms for H2O and N-2 adsorbates allows us to decouple and extract some insightful information underlying the complex water uptake phenomena. This work shows the promising performance of our modified zeolites that can be integrated into various AHP designs for buildings, electronics, and transportation applications. (C) 2014 Elsevier Inc. All rights reserved.

  3. Zeolite Y Adsorbents with High Vapor Uptake Capacity and Robust Cycling Stability for Potential Applications in Advanced Adsorption Heat Pumps

    PubMed Central

    Li, Xiansen; Narayanan, Shankar; Michaelis, Vladimir K.; Ong, Ta-Chung; Keeler, Eric G.; Kim, Hyunho; McKay, Ian S.; Griffin, Robert G.; Wang, Evelyn N.

    2014-01-01

    Modular and compact adsorption heat pumps (AHPs) promise an energy-efficient alternative to conventional vapor compression based heating, ventilation and air conditioning systems. A key element in the advancement of AHPs is the development of adsorbents with high uptake capacity, fast intracrystalline diffusivity and durable hydrothermal stability. Herein, the ion exchange of NaY zeolites with ingoing Mg2+ ions is systematically studied to maximize the ion exchange degree (IED) for improved sorption performance. It is found that beyond an ion exchange threshold of 64.1%, deeper ion exchange does not benefit water uptake capacity or characteristic adsorption energy, but does enhance the vapor diffusivity. In addition to using water as an adsorbate, the uptake properties of Mg,Na-Y zeolites were investigated using 20 wt.% MeOH aqueous solution as a novel anti-freeze adsorbate, revealing that the MeOH additive has an insignificant influence on the overall sorption performance. We also demonstrated that the labscale synthetic scalability is robust, and that the tailored zeolites scarcely suffer from hydrothermal stability even after successive 108-fold adsorption/desorption cycles. The samples were analyzed using N2 sorption, 27Al/29Si MAS NMR spectroscopy, ICP-AES, dynamic vapor sorption, SEM, Fick’s 2nd law and D-R equation regressions. Among these, close examination of sorption isotherms for H2O and N2 adsorbates allows us to decouple and extract some insightful information underlying the complex water uptake phenomena. This work shows the promising performance of our modified zeolites that can be integrated into various AHP designs for buildings, electronics, and transportation applications. PMID:25395877

  4. Strategies for increasing hydrogen storage capacity and adsorption energy in MOFs

    NASA Astrophysics Data System (ADS)

    Yaghi, Omar

    2007-03-01

    Storage of hydrogen in its molecular form is difficult and expensive because it requires employing either extremely high pressures as a gas or very low temperatures as a liquid. Worldwide effort is focused on storage of hydrogen with sufficient efficiency to allow its use in stationary and mobile fueling applications. DOE has set performance targets for on-board automobile storage systems to have densities of 60 mg H2/g (gravimetric) and 45 g H2/L (volumetric) for year 2010. These are system goals. Metal-organic frameworks (MOFs) have recently been identified as promising adsorbents (physisorption) for H2 storage, although little data are available for their adsorption behavior at saturation: a critical parameter for gauging the practicality of any material. This presentation will report adsorption data collected for seven MOF materials at 77 K which leads to saturation at pressures between 25 and 80 bar with uptakes from 2% to 7.5%. Strategies for increasing the adsorption energy of hydrogen in MOFs will also be presented.

  5. Superfine powdered activated carbon incorporated into electrospun polystyrene fibers preserve adsorption capacity.

    PubMed

    Apul, Onur G; Hoogesteijn von Reitzenstein, Natalia; Schoepf, Jared; Ladner, David; Hristovski, Kiril D; Westerhoff, Paul

    2017-03-17

    A composite material consisted of superfine powdered activated carbon (SPAC) and fibrous polystyrene (PS) was fabricated for the first time by electrospinning. SPAC is produced by pulverizing powdered activated carbon. The diameter of SPAC (100-400nm) is more than one hundred times smaller than conventional powdered activated carbon, but it maintains the internal pore structure based on organic micropollutant adsorption isotherms and specific surface area measurements. Co-spinning SPAC into PS fibers increased specific surface area from 6m(2)/g to 43m(2)/g. Unlike metal oxide nanoparticles, which are non-accessible for sorption from solution, electrospinning with SPAC created porous fibers. Composite SPAC-PS electrospun fibers, containing only 10% SPAC, had 30% greater phenanthrene sorption compared against PS fibers alone. SPAC particles embedded within the polymer were either partially or fully incorporated, and the accessibility of terminal adsorption sites were conserved. Conserving the adsorptive functionality of SPAC particles in electrospun non-woven polymeric fiber scaffolding can enable their application in environmental applications such as drinking water treatment.

  6. Determination of coalbed methane potential and gas adsorption capacity in Western Kentucky coals

    USGS Publications Warehouse

    Mardon, S.M.; Takacs, K.G.; Hower, J.C.; Eble, C.F.; Mastalerz, Maria

    2006-01-01

    The Illinois Basin has not been developed for Coalbed Methane (CBM) production. It is imperative to determine both gas content and other parameters for the Kentucky portion of the Illinois Basin if exploration is to progress and production is to occur in this area. This research is part of a larger project being conducted by the Kentucky Geological Survey to evaluate the CBM production of Pennsylvanian-age western Kentucky coals in Ohio, Webster, and Union counties using methane adsorption isotherms, direct gas desorption measurements, and chemical analyses of coal and gas. This research will investigate relationships between CBM potential and petrographic, surface area, pore size, and gas adsorption isotherm analyses of the coals. Maceral and reflectance analyses are being conducted at the Center for Applied Energy Research. At the Indiana Geological Survey, the surface area and pore size of the coals will be analyzed using a Micrometrics ASAP 2020, and the CO2 isotherm analyses will be conducted using a volumetric adsorption apparatus in a water temperature bath. The aforementioned analyses will be used to determine site specific correlations for the Kentucky part of the Illinois Basin. The data collected will be compared with previous work in the Illinois Basin and will be correlated with data and structural features in the basin. Gas composition and carbon and hydrogen isotopic data suggest mostly thermogenic origin of coalbed gas in coals from Webster and Union Counties, Kentucky, in contrast to the dominantly biogenic character of coalbed gas in Ohio County, Kentucky.

  7. Mercury Emission and Removal of a 135MW CFB Utility Boiler

    NASA Astrophysics Data System (ADS)

    Duan, Y. F.; Zhuo, Y. Q.; Wang, Y. J.; Zhang, L.; Yang, L. G.; Zhao, C. S.

    To evaluate characteristic of the mercury emission and removal from a circulating fluidized bed (CFB) boiler, a representative 135 MW CFB utility boiler was selected to take the onsite measurement of mercury concentrations in feeding coal, bottom ash, fly ash and flue gas using the US EPA recommended Ontario Hydro Method (OHM). The results show that particulate mercury is of majority in flue gas of the CFB boiler. Mercury removal rate of the electrostatic precipitator (ESP) reaches 98%. Mercury emission concentration in stack is only 0.062μg/Nm3, and the mass proportion of mercury in bottom ash is less than 1%. It was found that the fly ashes were highly adsorptive to flue gas mercury because of its higher unburned carbon content. Adsorption effect is related to carbon pore structural properties of fly ash and temperature of flue gas. However mercury adsorption capacity by fly ash can not be improved any more when unburned carbon content in fly ash increases further.

  8. The Relative Influence of Turbulence and Turbulent Mixing on the Adsorption of Mercury within a Gas-Sorbent Suspension

    EPA Science Inventory

    Our previous investigations demonstrated that entrained flow or in-flight adsorption can be a more effective and flexible approach to trace gas adsorption than fixed sorbent beds. The present investigation establishes the turbulent mixing that accompanies sorbent injection is an ...

  9. The Relative Influence of Turbulence and Turbulent Mixing on the Adsorption of Mercury within a Gas-Sorbent Suspension

    EPA Science Inventory

    Our previous investigations demonstrated that entrained flow or in-flight adsorption can be a more effective and flexible approach to trace gas adsorption than fixed sorbent beds. The present investigation establishes the turbulent mixing that accompanies sorbent injection is an ...

  10. Enhancing gas adsorption and separation capacity through ligand functionalization of microporous metal-organic framework structures.

    PubMed

    Zhao, Yonggang; Wu, Haohan; Emge, Thomas J; Gong, Qihan; Nijem, Nour; Chabal, Yves J; Kong, Lingzhu; Langreth, David C; Liu, Hui; Zeng, Heping; Li, Jing

    2011-04-26

    Hydroxyl- and amino- functionalized [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O leads to two new structures, [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O (BDC=terephthalic acid, TED=triethylenediamine, BDC-OH=2-hydroxylterephthalic acid, BDC-NH(2)=2-aminoterephthalic acid). Single-crystal X-ray diffraction and powder X-ray diffraction studies confirmed that the structures of both functionalized compounds are very similar to that of their parent structure. Compound [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O can be considered a 3D porous structure with three interlacing 1D channels, whereas both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O contain only 1D open channels as a result of functionalization of the BDC ligand by the OH and NH(2) groups. A notable decrease in surface area and pore size is thus observed in both compounds. Consequently, [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O takes up the highest amount of H(2) at low temperatures. Interestingly, however, both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O show significant enhancement in CO(2) uptake at room temperature, suggesting that the strong interactions between CO(2) and the functionalized ligands, indicating that surface chemistry, rather than porosity, plays a more important role in CO(2) adsorption. A comparison of single-component CO(2), CH(4), CO, N(2), and O(2) adsorption isotherms demonstrates that the adsorption selectivity of CO(2) over other small gases is considerably enhanced through functionalization of the frameworks. Infrared absorption spectroscopic measurements and theoretical calculations are also carried out to assess the effect of functional groups on CO(2) and H(2) adsorption potentials.

  11. Preparation and evaluation of coal-derived activated carbons for removal of mercury vapor from simulated coal combustion flue fases

    USGS Publications Warehouse

    Hsi, H.-C.; Chen, S.; Rostam-Abadi, M.; Rood, M.J.; Richardson, C.F.; Carey, T.R.; Chang, R.

    1998-01-01

    Coal-derived activated carbons (CDACs) were tested for their suitability in removing trace amounts of vapor-phase mercury from simulated flue gases generated by coal combustion. CDACs were prepared in bench-scale and pilot-scale fluidized-bed reactors with a three-step process, including coal preoxidation, carbonization, and then steam activation. CDACs from high-organicsulfur Illinois coals had a greater equilibrium Hg0 adsorption capacity than activated carbons prepared from a low-organic-sulfur Illinois coal. When a low-organic-sulfur CDAC was impregnated with elemental sulfur at 600 ??C, its equilibrium Hg0 adsorption capacity was comparable to the adsorption capacity of the activated carbon prepared from the high-organicsulfur coal. X-ray diffraction and sulfur K-edge X-ray absorption near-edge structure examinations showed that the sulfur in the CDACs was mainly in organic forms. These results suggested that a portion of the inherent organic sulfur in the starting coal, which remained in the CDACs, played an important role in adsorption of Hg0. Besides organic sulfur, the BET surface area and micropore area of the CDACs also influenced Hg0 adsorption capacity. The HgCl2 adsorption capacity was not as dependent on the surface area and concentration of sulfur in the CDACs as was adsorption of Hg0. The properties and mercury adsorption capacities of the CDACs were compared with those obtained for commercial Darco FGD carbon.

  12. Separation of complexed mercury from aqueous wastes using self-assembled mercaptan on mesoporous silica

    SciTech Connect

    Mattigod, S.V.; Feng, X.; Fryxell, G.E.; Liu, J.; Gong, M.

    1999-09-01

    Separation of Hg(II) from potassium iodide/sulfate wastes was studied using a novel mesoporous silica material containing self-assembled mercaptan groups. The adsorbent, consisting of self-assembled mercaptan on mesoporous silica (SAMMS) developed at Pacific Northwest National Laboratory (PNNL), was characterized as to its specificity, adsorption capacity, and kinetics for separation of mercury from potassium iodide/sulfate solutions. Aqueous speciation calculations indicated that a major fraction (92--99%) of dissolved mercury in the potassium iodide/sulfate wastes solutions existed as HgI{sub 4}{sup 2{minus}} species. The adsorption data showed that the mercury adsorption capacity of SAMMS material increased with decreasing iodide concentrations. The magnitude of calculated free energy of adsorption indicated that mercury adsorption on this adsorbent is typical of soft acid-soft base interactions. High specificity for anionic complexes of Hg(II) by the SAMMS material was confirmed by distribution coefficient measurements. The kinetics data indicated that the adsorption reactions occur very rapidly independent of Hg(II) concentrations and pH. These tests confirmed that SAMMS material can very effectively remove strongly complexed Hg(II) from aqueous wastes.

  13. Novel regenerable sorbent based on Zr-Mn binary metal oxides for flue gas mercury retention and recovery.

    PubMed

    Xie, Jiangkun; Qu, Zan; Yan, Naiqiang; Yang, Shijian; Chen, Wanmiao; Hu, Lingang; Huang, Wenjun; Liu, Ping

    2013-10-15

    To capture and recover mercury from coal-fired flue gas, a series of novel regenerable sorbents based on Zr-Mn binary metal oxides were prepared and employed at a relatively low temperature. PXRD, TEM, TPR, XPS, and N2-adsorption methods were employed to characterize the sorbents. The Hg(0) adsorption performance of the sorbents was tested, and the effects of the main operation parameters and the gas components on the adsorption were investigated. Zr significantly improved the sorbent's mercury capacity, which was nearly 5mg/g for Zr0.5Mn0.5Oy. Furthermore, the spent sorbent could be regenerated by heating to 350°C, and the highly concentrated elemental mercury released could be facilely recycled. Therefore, a much greener process for mercury capture and recovery could be anticipated based on this regenerable sorbent. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. One-step synthesis of a novel N-doped microporous biochar derived from crop straws with high dye adsorption capacity.

    PubMed

    Lian, Fei; Cui, Guannan; Liu, Zhongqi; Duo, Lian; Zhang, Guilong; Xing, Baoshan

    2016-07-01

    N-doping is one of the most promising strategies to improve the adsorption capacity and selectivity of carbon adsorbents. Herein, synthesis, characterization and dye adsorption of a novel N-doped microporous biochar derived from direct annealing of crop straws under NH3 is presented. The resultant products exhibit high microporosity (71.5%), atomic percentage of nitrogen (8.81%), and adsorption capacity to dyes, which is about 15-20 times higher than that of original biochar. Specifically, for the sample NBC800-3 pyrolyzed at 800°C in NH3 for 3 h, its adsorption for acid orange 7 (AO7, anionic) and methyl blue (MB, cationic) is up to 292 mg g(-1) and 436 mg g(-1), respectively, which is among the highest ever reported for carbonaceous adsorbents. The influences of N-doping and porous structure on dye adsorption of the synthesized carbons are also discussed, where electrostatic attraction, π-π electron donor-accepter interaction, and Lewis acid-base interaction mainly contribute to AO7 adsorption, and surface area (especially pore-filling) dominates MB adsorption. The N-doped biochar can be effectively regenerated and reused through direct combustion and desorption approaches.

  15. Effect of carboxyethylation degree on the adsorption capacity of Cu(II) by N-(2-carboxyethyl)chitosan from squid pens.

    PubMed

    Huang, Jun; Xie, Haihua; Ye, Hui; Xie, Tian; Lin, Yuecheng; Gong, Jinyan; Jiang, Chengjun; Wu, Yuanfeng; Liu, Shiwang; Cui, Yanli; Mao, Jianwei; Mei, Lehe

    2016-03-15

    Chitosan was prepared by N-deacetylation of squid pens β-chitin, and N-carboxyethylated chitosan (N-CECS) with different degrees of substitution (DS) were synthesized. DS values of N-CECS derivatives calculated by (1)H nuclear magnetic resonance (NMR) spectroscopy were 0.60, 1.02 and 1.46, respectively. The adsorption capacity of Cu(II) by N-CECS correlated well with the DS and pH ranging from 3.2 to 5.8. The maximum Cu(II) adsorption capacity (qm) of all three N-CECS at pH 5.4 was 207.5mg g(-1), which was 1.4-fold higher than that of chitosan. The adsorption equilibrium process was better described by the Langmuir than Freundlich isotherm model. Adsorption of Cu(II) ion onto N-CECS followed a pseudo-second order mechanism with chemisorption as the rate-limiting step. In a ternary adsorption system, the adsorption capacity of Cu(II) by N-CECS also presented high values, and qm for Cu(II), Cd(II), and Pb(II) were 150.2, 28.8, and 187.9mg g(-1), respectively.

  16. Mercury capture within coal-fired power plant electrostatic precipitators: model evaluation.

    PubMed

    Clack, Herek L

    2009-03-01

    Efforts to reduce anthropogenic mercury emissions worldwide have recently focused on a variety of sources, including mercury emitted during coal combustion. Toward that end, much research has been ongoing seeking to develop new processes for reducing coal combustion mercury emissions. Among air pollution control processes that can be applied to coal-fired boilers, electrostatic precipitators (ESPs) are by far the most common, both on a global scale and among the principal countries of India, China, and the U.S. that burn coal for electric power generation. A previously reported theoretical model of in-flight mercury capture within ESPs is herein evaluated against data from a number of full-scale tests of activated carbon injection for mercury emissions control. By using the established particle size distribution of the activated carbon and actual or estimated values of its equilibrium mercury adsorption capacity, the incremental reduction in mercury concentration across each ESP can be predicted and compared to experimental results. Because the model does not incorporate kinetics associated with gas-phase mercury transformation or surface adsorption, the model predictions representthe mass-transfer-limited performance. Comparing field data to model results reveals many facilities performing at or near the predicted mass-transfer-limited maximum, particularly at low rates of sorbent injection. Where agreement is poor between field data and model predictions, additional chemical or physical phenomena may be responsible for reducing mercury removal efficiencies.

  17. Trace vanadium analysis by catalytic adsorptive stripping voltammetry using mercury-coated micro-wire and polystyrene-coated bismuth film electrodes.

    PubMed

    Dansby-Sparks, Royce; Chambers, James Q; Xue, Zi-Ling

    2009-06-08

    An electrochemical technique has been developed for ultra-trace (ng L(-1)) vanadium (V) measurement. Catalytic adsorptive stripping voltammetry for V analysis was developed at mercury-coated gold micro-wire electrodes (MWEs, 100 microm) in the presence of gallic acid (GA) and bromate ion. A potential of -0.275 V (vs Ag/AgCl) was used to accumulate the complex in acetate buffer (pH 5.0) at the electrode surface followed by a differential pulse voltammetric scan. Parameters affecting the electrochemical response, including pH, concentration of GA and bromate, deposition potential and time have been optimized. Linear response was obtained in the 0-1000 ng L(-1) range (2 min deposition), with a detection limit of 0.88 ng L(-1). The method was validated by comparison of results for an unknown solution of V by atomic absorption measurement. The protocol was evaluated in a real sample by measuring the amount of V in river water samples. Thick bismuth film electrodes with protective polystyrene films have also been made and evaluated as a mercury free alternative. However, ng L(-1) level detection was only attainable with extended (10 min) deposition times. The proposed use of MWEs for the detection of V is sensitive enough for future use to test V concentration in biological fluids treated by the advanced oxidation process (AOP).

  18. Trace vanadium analysis by catalytic adsorptive stripping voltammetry using mercury-coated micro-wire and polystyrene-coated bismuth film electrodes

    PubMed Central

    Dansby-Sparks, Royce; Chambers, James Q.; Xue, Zi-Ling

    2009-01-01

    An electrochemical technique has been developed for ultra trace (ngL−1) vanadium (V) measurement. Catalytic adsorptive stripping voltammetry for V analysis was developed at mercury-coated gold micro-wire (MWE, 100 μm) electrodes in the presence of gallic acid (GA) and bromate ion. A potential of −0.275 V (vs Ag/AgCl) was used to accumulate the complex in acetate buffer (pH 5.0) at the electrode surface followed by a differential pulse voltammetric scan. Parameters affecting the electrochemical response, including pH, concentration of GA and bromate, deposition potential and time have been optimized. Linear response was obtained in the 0–1000 ngL−1 range (2 min deposition), with a detection limit of 0.88 ngL−1. The method was validated by comparison of results for an unknown solution of V by atomic absorption measurement. The protocol was evaluated in a real sample by measuring the amount of V in river water samples. Thick bismuth film electrodes with protective polystyrene films have also been made and evaluated as a mercury free alternative. However, ngL−1 level detection was only attainable with extended (10 min) deposition times. The proposed use of MWEs for the detection of V is sensitive enough for future use to test V concentration in biological fluids treated by the advanced oxidation process (AOP). PMID:19446059

  19. Adsorptive removal of Cr3+ from aqueous solutions using chitosan microfibers immobilized with plant polyphenols as biosorbents with high capacity and selectivity

    NASA Astrophysics Data System (ADS)

    Zhang, Ting; Wang, Yujia; Kuang, Yiwen; Yang, Ruilin; Ma, Jun; Zhao, Shilin; Liao, Yang; Mao, Hui

    2017-05-01

    A novel biosorbent was facilely prepared by immobilizing bayberry tannin (BT, a typical natural polyphenols) onto chitosan microfiber (CM). The as-prepared CM-BT adsorbent featured to a well-defined microfibrous morphology and highly distributed adsorption sites, which was highly efficient and selective for the adsorptive removal of Cr3+ from aqueous solutions. Based on batch experiments, the adsorption of Cr3+ on CM-BT was pH-dependent, and the optimized adsorption pH was determined to be 5.5. The adsorption capacity of CM-BT to Cr3+ was high up to 20.90 mg/g. The co-existing cations, such as Mg2+, Ca2+, Fe3+ and Cu2+, exhibited no significant influences on the adsorption of Cr3+ on CM-BT. The adsorption kinetics were well fitted by the pseudo-second-order rate model (R2 > 0.99) while the adsorption isotherms were well described by the Langmuir model (R2 > 0.98). Importantly, CM-BT was effective for the continues treatment of low concentration Cr3+ (2.0 mg/L) contaminated wastewater. Before reached the breakthrough point (5% of the initial Cr3+ concentration, 0.1 mg/L), the treated volume was as high as 894 bed volume, manifesting the great potential of CM-BT in practical treatment of Cr3+ contaminated wastewater.

  20. Effects of Dendropanax morbifera Léveille extracts on cadmium and mercury secretion as well as oxidative capacity: A randomized, double-blind, placebo-controlled trial.

    PubMed

    Seo, Jae Sam; Yoo, Dae Young; Jung, Hyo Young; Kim, Dong-Woo; Hwang, In Koo; Lee, Jong Young; Moon, Seung Myung

    2016-05-01

    In this randomized, double-blind, placebo controlled clinical trial, the effects of Dendropanax morbifera (D. morbifera) Léveille on heavy metal (cadmium and mercury) excretion as well as on lipid peroxidation and Cu, Zn-superoxide dismutase (SOD1) activity were investigated. For this study, tablets containing placebo or 300 mg of the leaf extract from D. morbifera Léveille were used. A total of 60 eligible healthy subjects were enrolled in this randomized, double-blind, placebo-controlled study. The differences in cadmium, mercury, and malondialdehyde (MDA) levels and SOD1 activity were measured in the serum 60 days after treatment with placebo or D. morbifera Léveille extracts. No significant differences between baseline characteristics and biochemical values were identified in subjects in the placebo and D. morbifera Léveille groups. Serum levels of cadmium, mercury and MDA decreased following consumption of D. morbifera Léveille extracts; however, no significant differences were identified. In addition, female, but not male, subjects who consumed D. morbifera Léveille extracts showed a significant increase in SOD1 activity. This result suggests that chronic consumption of D. morbifera Léveille extract can help to facilitate excretion of cadmium and mercury from serum and increase the antioxidant capacity in humans.

  1. Effects of Dendropanax morbifera Léveille extracts on cadmium and mercury secretion as well as oxidative capacity: A randomized, double-blind, placebo-controlled trial

    PubMed Central

    SEO, JAE SAM; YOO, DAE YOUNG; JUNG, HYO YOUNG; KIM, DONG-WOO; HWANG, IN KOO; LEE, JONG YOUNG; MOON, SEUNG MYUNG

    2016-01-01

    In this randomized, double-blind, placebo controlled clinical trial, the effects of Dendropanax morbifera (D. morbifera) Léveille on heavy metal (cadmium and mercury) excretion as well as on lipid peroxidation and Cu, Zn-superoxide dismutase (SOD1) activity were investigated. For this study, tablets containing placebo or 300 mg of the leaf extract from D. morbifera Léveille were used. A total of 60 eligible healthy subjects were enrolled in this randomized, double-blind, placebo-controlled study. The differences in cadmium, mercury, and malondialdehyde (MDA) levels and SOD1 activity were measured in the serum 60 days after treatment with placebo or D. morbifera Léveille extracts. No significant differences between baseline characteristics and biochemical values were identified in subjects in the placebo and D. morbifera Léveille groups. Serum levels of cadmium, mercury and MDA decreased following consumption of D. morbifera Léveille extracts; however, no significant differences were identified. In addition, female, but not male, subjects who consumed D. morbifera Léveille extracts showed a significant increase in SOD1 activity. This result suggests that chronic consumption of D. morbifera Léveille extract can help to facilitate excretion of cadmium and mercury from serum and increase the antioxidant capacity in humans. PMID:27123258

  2. Facile synthesis of hydroxy-modified MOF-5 for improving the adsorption capacity of hydrogen by lithium doping.

    PubMed

    Kubo, Masaru; Hagi, Hayato; Shimojima, Atsushi; Okubo, Tatsuya

    2013-11-01

    A facile synthesis of partially hydroxy-modified MOF-5 and its improved H2-adsorption capacity by lithium doping are reported. The reaction of Zn(NO3)2·6H2O with a mixture of terephthalic acid (H2BDC) and 2-hydroxyterephthalic acid (H2BDC-OH) in DMF gave hydroxy-modified MOF-5 (MOF-5-OH-x), in which the molar fraction (x) of BDC-OH(2-) was up to 0.54 of the whole ligand. The MOF-5-OH-x frameworks had high BET surface areas (about 3300 m(2) g(-1)), which were comparable to that of MOF-5. We suggest that the MOF-5-OH-x frameworks are formed by the secondary growth of BDC(2-)-rich MOF-5 seed crystals, which are nucleated during the early stage of the reaction. Subsequent Li doping into MOF-5-OH-x results in increased H2 uptake at 77 K and 0.1 MPa from 1.23 to 1.39 wt.% and an increased isosteric heat of H2 adsorption from 5.1-4.2 kJ mol(-1) to 5.5-4.4 kJ mol(-1).

  3. MOF-derived ZnO and ZnO@C composites with high photocatalytic activity and adsorption capacity.

    PubMed

    Yang, Seung Jae; Im, Ji Hyuk; Kim, Taehoon; Lee, Kunsil; Park, Chong Rae

    2011-02-15

    Nanostructured ZnO materials have unique and highly attractive properties and have inspired interest in their research and development. This paper presents a facile method for the preparation of novel ZnO-based nanostructured architectures using a metal organic framework (MOF) as a precursor. In this approach, ZnO nanoparticles and ZnO@C hybrid composites were produced under several heating and atmospheric (air or nitrogen) conditions. The resultant ZnO nanoparticles formed hierarchical aggregates with a three-dimensional cubic morphology, whereas ZnO@C hybrid composites consisted of faceted ZnO crystals embedded within a highly porous carbonaceous species, as determined by several characterization methods. The newly synthesized nanomaterials showed relatively high photocatalytic decomposition activity and significantly enhanced adsorption capacities for organic pollutants.

  4. Functionalized diatom silica microparticles for removal of mercury ions

    PubMed Central

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

    2012-01-01

    Diatom silica microparticles were chemically modified with self-assembled monolayers of 3-mercaptopropyl-trimethoxysilane (MPTMS), 3-aminopropyl-trimethoxysilane (APTES) and n-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS), and their application for the adsorption of mercury ions (Hg(II)) is demonstrated. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses revealed that the functional groups (–SH or –NH2) were successfully grafted onto the diatom silica surface. The kinetics and efficiency of Hg(II) adsorption were markedly improved by the chemical functionalization of diatom microparticles. The relationship among the type of functional groups, pH and adsorption efficiency of mercury ions was established. The Hg(II) adsorption reached equilibrium within 60 min with maximum adsorption capacities of 185.2, 131.7 and 169.5 mg g−1 for particles functionalized with MPTMS, APTES and AEAPTMS, respectively. The adsorption behavior followed a pseudo-second-order reaction model and Langmuirian isotherm. These results show that mercapto- or amino-functionalized diatom microparticles are promising natural, cost-effective and environmentally benign adsorbents suitable for the removal of mercury ions from aqueous solutions. PMID:27877475

  5. Functionalized diatom silica microparticles for removal of mercury ions.

    PubMed

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

    2012-02-01

    Diatom silica microparticles were chemically modified with self-assembled monolayers of 3-mercaptopropyl-trimethoxysilane (MPTMS), 3-aminopropyl-trimethoxysilane (APTES) and n-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS), and their application for the adsorption of mercury ions (Hg(II)) is demonstrated. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses revealed that the functional groups (-SH or -NH2) were successfully grafted onto the diatom silica surface. The kinetics and efficiency of Hg(II) adsorption were markedly improved by the chemical functionalization of diatom microparticles. The relationship among the type of functional groups, pH and adsorption efficiency of mercury ions was established. The Hg(II) adsorption reached equilibrium within 60 min with maximum adsorption capacities of 185.2, 131.7 and 169.5 mg g(-1) for particles functionalized with MPTMS, APTES and AEAPTMS, respectively. The adsorption behavior followed a pseudo-second-order reaction model and Langmuirian isotherm. These results show that mercapto- or amino-functionalized diatom microparticles are promising natural, cost-effective and environmentally benign adsorbents suitable for the removal of mercury ions from aqueous solutions.

  6. Adsorption capacity of multiple DNA sources to clay minerals and environmental soil matrices less than previously estimated.

    PubMed

    Gardner, Courtney M; Gunsch, Claudia K

    2017-05-01

    The cultivation and consumption of transgenic crops continues to be a widely debated topic, as the potential ecological impacts are not fully understood. In particular, because antibiotic resistance genes (ARGs) have historically been used as selectable markers in the genetic engineering of transgenic crops, it is important to determine if the genetic constructs found in decomposing transgenic crops persist long enough in the environment and if they can be transferred horizontally to indigenous microorganisms. In the present study, we address the question of persistence. Others have also estimated the DNA adsorption capacity of various clays, but have done so by manipulating the surface charge and size of particles tested which may overestimate sorption and underestimate the DNA available for horizontal transfer. In the present study, isotherms were generated using model Calf Thymus DNA and transgenic maize DNA without surface modification. Montmorillonite, kaolinite, and 3 soil mixtures with varying clay content were used in this study. The adsorption capacity of pure montmorillonite and kaolinite minerals was found to be one to two orders of magnitude less than previously estimated likely due to the distribution of clay particle sizes and heteroionic particle surface charge. However, it appears that a substantial amount of DNA is still able to adsorb onto these matrices (up to 200 mg DNA per gram of clay) suggesting the potential availability of free transgenic DNA in the environment may still be significant. Future studies should be conducted to determine the fate of these genes in agricultural soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Adsorption of 2,4,6-trinitrotoluene on carboxylated porous polystyrene microspheres

    NASA Astrophysics Data System (ADS)

    Ye, Zhengfang; Meng, Qingqiang; Lu, Shengtao

    2012-02-01

    Large-pore-size (150 nm) polystyrene (PSt) microspheres were carboxylated with phthalic anhydride (PA) through Friedel-Crafts acetylation to study the adsorption of 2,4,6-trinitrotoluene (TNT) on this material from aqueous solution. The scanning electron microscope (SEM) images and mercury porosimetry measurements (MPM) of the microspheres showed that the pore structure was unchanged during the reaction. High adsorption capacity (11.2 mg g-1 of suction-dried adsorbent) and adsorption rate (33.9 mg g-1 h-1) for TNT were observed during the study. As shown by the adsorption isotherm, the adsorption of TNT on PA-PSt can be described by the Freundlich adsorption equation, indicating heterogeneous adsorption process. On-column adsorption of TNT on PA-PSt and elution indicated that TNT can be completely removed from aqueous solution and condensed into acetone.

  8. Effect of carbonation temperature on CO{sub 2} adsorption capacity of CaO derived from micro/nanostructured aragonite CaCO{sub 3}

    SciTech Connect

    Hlaing, Nwe Ni; Sreekantan, Srimala; Hinode, Hirofumi Kurniawan, Winarto; Thant, Aye Aye; Othman, Radzali; Mohamed, Abdul Rahman; Salime, Chris

    2016-07-06

    Recent years, CaO-based synthetic materials have been attracted attention as potential adsorbents for CO{sub 2} capture mainly due to their high CO{sub 2} adsorption capacity. In this study, micro/nanostructured aragonite CaCO{sub 3} was synthesized by a simple hydrothermal method with using polyacrylamide (PAM). The structural, morphological and thermal properties of the synthesized sample were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and thermogravimetry analysis (TG-DTA). The XRD and FESEM results showed that the obtained sample was aragonite CaCO{sub 3} with aggregated nanorods and microspheres composed of nanorods. A TG-DTA apparatus with Thermoplus 2 software was used to investigate the effect of carbonation temperature on the CO{sub 2} adsorption capacity of CaO derived from aragonite CaCO{sub 3} sample. At 300 °C, the sample reached the CO{sub 2} adsorption capacity of 0.098 g-CO{sub 2}/g-adsorbent, whereas the sample achieved the highest capacity of 0.682 g-CO{sub 2}/g-adsorbent at 700 °C. The results showed that the carbonation temperature significantly influenced on the CO{sub 2} adsorption capacity of the CaO derived from aragonite CaCO{sub 3}.

  9. Dendritic silica nanomaterials (KCC-1) with fibrous pore structure possess high DNA adsorption capacity and effectively deliver genes in vitro.

    PubMed

    Huang, Xiaoxi; Tao, Zhimin; Praskavich, John C; Goswami, Anandarup; Al-Sharab, Jafar F; Minko, Tamara; Polshettiwar, Vivek; Asefa, Tewodros

    2014-09-16

    The pore size and pore structure of nanoporous materials can affect the materials' physical properties, as well as potential applications in different areas, including catalysis, drug delivery, and biomolecular therapeutics. KCC-1, one of the newest members of silica nanomaterials, possesses fibrous, large pore, dendritic pore networks with wide pore entrances, large pore size distribution, spacious pore volume and large surface area--structural features that are conducive for adsorption and release of large guest molecules and biomacromolecules (e.g., proteins and DNAs). Here, we report the results of our comparative studies of adsorption of salmon DNA in a series of KCC-1-based nanomaterials that are functionalized with different organoamine groups on different parts of their surfaces (channel walls, external surfaces or both). For comparison the results of our studies of adsorption of salmon DNA in similarly functionalized, MCM-41 mesoporous silica nanomaterials with cylindrical pores, some of the most studied silica nanomaterials for drug/gene delivery, are also included. Our results indicate that, despite their relatively lower specific surface area, the KCC-1-based nanomaterials show high adsorption capacity for DNA than the corresponding MCM-41-based nanomaterials, most likely because of KCC-1's large pores, wide pore mouths, fibrous pore network, and thereby more accessible and amenable structure for DNA molecules to diffuse through. Conversely, the MCM-41-based nanomaterials adsorb much less DNA, presumably because their outer surfaces/cylindrical channel pore entrances can get blocked by the DNA molecules, making the inner parts of the materials inaccessible. Moreover, experiments involving fluorescent dye-tagged DNAs suggest that the amine-grafted KCC-1 materials are better suited for delivering the DNAs adsorbed on their surfaces into cellular environments than their MCM-41 counterparts. Finally, cellular toxicity tests show that the KCC-1-based

  10. Development of Novel Activated Carbon-Based Adsorbents for Control of Mercury Emission From Coal-Fired Power Plants

    SciTech Connect

    Radisav D. Vidic

    1997-09-08

    The overall objective of this study is to evaluate pertinent design and operational parameters that would enable successful application of activated carbon adsorption for the reduction of mercury emissions from coal-fired power plants. The study will evaluate the most suitable impregnate such as sulfur, chloride and other chelating agents for its ability to enhance the adsorptive capacity of activated carbon for mercury vapor under various process conditions. The main process variables to be evaluated include temperature, mercury concentration and speciation, relative humidity, oxygen content, and presence of SO2 and NOx in the flue gas. The optimal amount of impregnate for each of these carbons will be determined based on the exhibited performance. Another important parameter which governs the applicability of adsorption technology for the flue gas clean up is the rate at which vapor phase mercury is being removed from the flue gas by activated carbon. Therefore, the second part of this study will evaluate the adsorption kinetics using the impregnated activated carbons listed above. The rate of mercury uptake will also be evaluated under the process conditions that are representative of coal-fired power plants. Concerned with the ability of the adsorbed mercury to migrate back into the environment once saturated adsorbent is removed from the system, the study will also focus on the mercury desorption rate as a function of the type of impregnate, loading conditions, and the time of contact prior to disposal.

  11. Development of a Novel Activated Carbon Based Adsorbents for control of Mercury Emissions from Coal-Fired Power Plants

    SciTech Connect

    Vidic, R.D.

    1997-03-17

    The overall objective of this study is to evaluate pertinent design and operational parameters that would enable successful application of activated carbon adsorption for the reduction of mercury emissions from coal-fired power plants. The study will evaluate the most suitable impregnate such as sulfur, chloride and other chelating agents for its ability to enhance the adsorptive capacity of activated carbon for mercury vapor under various process conditions. The main process variables to be evaluated include temperature, mercury concentration and speciation, relative humidity, oxygen content, and presence of S0{sub 2} and NO{sub x} in the flue gas. The optimal amount of impregnate for each of these carbons will be determined based on the exhibited performance. Another important parameter which governs the applicability of adsorption technology for the flue gas clean up is the rate at which vapor phase mercury is being removed from the flue gas by activated carbon. Therefore, the second part of this study will evaluate the adsorption kinetics using the impregnated activated carbons listed above. The rate of mercury uptake will also be evaluated under the process conditions that are representative of coal-fired power plants. Concerned with the ability of the adsorbed mercury to migrate back into the environment once saturated adsorbent is removed from the system, the study will also focus on the mercury desorption rate as a function of the type of impregnate, loading conditions, and the time of contact prior to disposal.

  12. Graphene oxide papers with high water adsorption capacity for air dehumidification.

    PubMed

    Liu, Renlong; Gong, Tao; Zhang, Kan; Lee, Changgu

    2017-08-29

    Graphene oxide (GO) has shown a high potential to adsorb and store water molecules due to the oxygen-containing functional groups on its hydrophilic surface. In this study, we characterized the water absorbing properties of graphene oxide in the form of papers. We fabricated three kinds of graphene oxide papers, two with rich oxygen functional groups and one with partial chemical reduction, to vary the oxygen/carbon ratio and found that the paper with high oxygen content has higher moisture adsorption capability. For the GO paper with reduction, the overall moisture absorbance was reduced. However, the absorbance at high humidity was significantly improved due to direct formation of multilayer water vapor in the system, which derived from the weak interaction between the adsorbent and the adsorbate. To demonstrate one application of GO papers as a desiccant, we tested grape fruits with and without GO paper. The fruits with a GO paper exhibited longer-term preservation with delayed mold gathering because of desiccation effect from the paper. Our results suggest that GO will find numerous practical applications as a desiccant and is a promising material for moisture desiccation and food preservation.

  13. Regenerative process for removal of mercury and other heavy metals from gases containing H.sub.2 and/or CO

    DOEpatents

    Jadhav, Raja A.

    2009-07-07

    A method for removal of mercury from a gaseous stream containing the mercury, hydrogen and/or CO, and hydrogen sulfide and/or carbonyl sulfide in which a dispersed Cu-containing sorbent is contacted with the gaseous stream at a temperature in the range of about 25.degree. C. to about 300.degree. C. until the sorbent is spent. The spent sorbent is contacted with a desorbing gaseous stream at a temperature equal to or higher than the temperature at which the mercury adsorption is carried out, producing a regenerated sorbent and an exhaust gas comprising released mercury. The released mercury in the exhaust gas is captured using a high-capacity sorbent, such as sulfur-impregnated activated carbon, at a temperature less than about 100.degree. C. The regenerated sorbent may then be used to capture additional mercury from the mercury-containing gaseous stream.

  14. Effect of the incorporation of nitrogen to a carbon matrix on the selectivity and capacity for adsorption of dibenzothiophenes from model diesel fuel.

    PubMed

    Seredych, Mykola; Hulicova-Jurcakova, Denisa; Bandosz, Teresa J

    2010-01-05

    Two synthetic, polymer-derived carbons were modified with urea to incorporate nitrogen surface functional groups. Then they were investigated as adsorbents of dibenzothiophene (DBT) and 4, 6-dimethyldibenzothiophene (DMDBT) from simulated diesel fuel under dynamic conditions with the total concentration of sulfur being 20 ppmw. The materials before and after adsorption were characterized using elemental analysis, XPS, adsorption of nitrogen, potentiometric titration, and thermal analysis. The incorporation of nitrogen species caused a visible increase in the adsorption capacity. However, selectivity evaluated on the basis of the adsorption of naphthalene decreased. Whereas at low surface coverage the volume of pores smaller than 10 A is important, with the progress of adsorption the surface chemistry gradually starts to play a more important role via either polar or acid/base interactions. The latter are important for the selectivity of adsorption when the aromatic hydrocarbons are present. Although polar interactions are weaker than the acid-base ones, the centers that they represent seem to be more favorable to attract DBT and DMDBT than arenes. There is an indication that nitrogen-containing groups contribute to chemical transformations of DBT and DMDBT/oxidation and promote the involvement of oxygen from the surface groups in the reactive adsorption.

  15. CO2 Adsorption in Low-Rank Coals: Progress Toward Assessing the National Capacity to Store CO2 in the Subsurface

    NASA Astrophysics Data System (ADS)

    Stanton, R. W.; Burruss, R. C.; Flores, R. M.; Warwick, P. D.

    2001-05-01

    Subsurface environments for geologic storage of CO2 from combustion of fossil fuel include saline formations, depleted oil and gas reservoirs, and unmineable coalbeds. Of these environments, storage in petroleum reservoirs and coal beds offers a potential economic benefit of enhanced recovery of energy resources. Meaningful assessment of the volume and geographic distribution of storage sites requires quantitative estimates of geologic factors that control storage capacity. The factors that control the storage capacity of unmineable coalbeds are poorly understood. In preparation for a USGS assessment of CO2 storage capacity we have begun new measurements of CO2 and CH4 adsorption isotherms of low-rank coal samples from 4 basins. Initial results for 13 samples of low-rank coal beds from the Powder River Basin (9 subbituminous coals), Greater Green River Basin (1 subbituminous coal), Williston Basin (2 lignites) and the Gulf Coast (1 lignite) indicate that their adsorption capacity is up to 10 times higher than it is for CH4. These values contrast with published measurements of the CO2 adsorption capacity of bituminous coals from the Fruitland Formation, San Juan basin, and Gates Formation, British Columbia, that indicate about twice as much carbon dioxide as methane can be adsorbed on coals. Because CH4 adsorption isotherms are commonly measured on coals, CO2 adsorption capacity can be estimated if thecorrect relationship between the gases is known. However, use a factor to predict CO2 adsorption that is twice that of CH4 adsorption, which is common in the published literature, grossly underestimates the storage capacity of widely distributed, thick low-rank coal beds. Complete petrographic and chemical characterization of these low-rank coal samples is in progress. Significant variations in adsorption measurements among samples are depicted depending on the reporting basis used. Properties were measured on an "as received" (moist) basis but can be converted to a

  16. Stepwise engineering of pore environments and enhancement of CO2/R22 adsorption capacity through dynamic spacer installation and functionality modification.

    PubMed

    Chen, Cheng-Xia; Qiu, Qian-Feng; Cao, Chen-Chen; Pan, Mei; Wang, Hai-Ping; Jiang, Ji-Jun; Wei, Zhang-Wen; Zhu, Kelong; Li, Guangqin; Su, Cheng-Yong

    2017-09-26

    Through stepwise post-synthetic spacer insertion and click reactions, six Zr-MOFs with different types and amounts of functional groups have been constructed based on proto-MOF PCN-700. Their gas adsorption capacities and selectivities have been greatly improved and finely tuned, demonstrating the combinatorial effect of pore surface modification and pore space partition.

  17. Sn-Mn binary metal oxides as non-carbon sorbent for mercury removal in a wide-temperature window.

    PubMed

    Xie, Jiangkun; Xu, Haomiao; Qu, Zan; Huang, Wenjun; Chen, Wanmiao; Ma, Yongpeng; Zhao, Songjian; Liu, Ping; Yan, Naiqiang

    2014-08-15

    A series of Sn-Mn binary metal oxides were prepared through co-precipitation method. The sorbents were characterized by powder X-ray diffraction (powder XRD), transmission electronic microscopy (TEM), H2-temperature-programmed reduction (H2-TPR) and NH3-temperature-programmed desorption (NH3-TPD) methods. The capability of the prepared sorbents for mercury adsorption from simulated flue gas was investigated by fixed-bed experiments. Results showed that mercury adsorption on pure SnO2 particles was negligible in the test temperature range, comparatively, mercury capacity on MnOx at low temperature was relative high, but the capacity would decrease significantly when the temperature was elevated. Interestingly, for Sn-Mn binary metal oxide, mercury capacity increased not only at low temperature but also at high temperature. Furthermore, the impact of SO2 on mercury adsorption capability of Sn-Mn binary metal oxides was also investigated and it was noted that the effect at low temperature was different comparing with that of high temperature. The mechanism was investigated by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs). Moreover, a mathematic model was built to calculate mercury desorption activation energy from Sn to Mn binary metal oxides.

  18. The role of counter ions in nano-hematite synthesis: Implications for surface area and selenium adsorption capacity.

    PubMed

    Lounsbury, Amanda W; Yamani, Jamila S; Johnston, Chad P; Larese-Casanova, Philip; Zimmerman, Julie B

    2016-06-05

    Nano metal oxides are of interest for aqueous selenium (Se) remediation, and as such, nano-hematite (nα-Fe2O3) was examined for use as a Se adsorbent. The effect of surface area on adsorption was also studied. nα-Fe2O3 particles were synthesized from Fe(NO3)3 and FeCl3 via forced hydrolysis. The resulting particles have similar sizes, morphologies, aggregate size, pore size, and PZC. The nα-Fe2O3 from FeCl3 (nα-Fe2O3-C) differs from the nα-Fe2O3 from Fe(NO3)3 (nα-Fe2O3-N) with a ∼25±2m(2)/g greater surface area. Selenite Se(IV) adsorption capacity on nα-Fe2O3 has a qmax ∼17mg/g for the freeze-dried and re-suspended nα-Fe2O3. The Δqmax for nα-Fe2O3 from Fe(NO3)3 and FeCl3 that remained in suspension was 4.6mg/g. For selenate Se(VI), the freeze-dried and re-suspended particles realize a Δqmax= 1.5mg/g for nα-Fe2O3 from Fe(NO3)3 and FeCl3. The nα-Fe2O3 from Fe(NO3)3 and FeCl3 that remained in suspension demonstrated Se(VI) Δqmax=5.4mg/g. In situ ATR-FTIR isotherm measurements completed for Se(VI) at a pH 6 suggest that Se(VI) forms primarily outer-sphere complexes with nα-Fe2O3 synthesized from both salts.

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

    SciTech Connect

    Gill, Gary A.; Kuo, Li-Jung; Strivens, Jonathan E.; Park, Jiyeon; Bonheyo, George T.; Jeters, Robert T.; Schlafer, Nicholas J.; Wood, Jordana R.

    2015-08-31

    PNNL has developed a recirculating flume system for exposing braided adsorbent material to natural seawater under realistic temperature and flow-rate exposure conditions. The flumes are constructed of transparent acrylic material; they allow external light to pass into the flumes and permit photosynthetic growth of naturally present marine organisms (biofouling). Because the system consists of two flumes, replicate experiments can be conducted in which one of the flumes can be manipulated relative to the other. For example, one flume can be darkened to eliminate light exposure by placing a black tarp over the flume such that dark/light experiments can be conducted. Alternatively, two different braided adsorbents can be exposed simultaneously with no potential cross contamination issues. This report describes the first use of the PNNL flume system to study the impact of biofouling on adsorbent capacity. Experiments were conducted with the ORNL AI8 braided adsorbent material in light-exposed and darkened flumes for a 42-day exposure experiment. The major objective of this effort is to develop a system for the exposure of braided adsorbent material to unfiltered seawater, and to demonstrate the system by evaluating the performance of adsorption material when it is exposed to natural marine biofouling as it would be when the technology is used in the marine environment. Exposures of amidoxime-based polymeric braid adsorbents prepared by Oak Ridge Natural Laboratory (ORNL) were exposed to ambient seawater at 20°C in a flume system. Adsorption kinetics and adsorption capacity were assessed using time series determinations of uranium adsorption and one-site ligand saturation modeling. Biofouling in sunlight surface seawater has the potential to significantly add substantial biogenic mass to adsorption material when it is exposed for periods greater than 21 days. The observed biomass increase in the light flume was approximately 80% of the adsorbent mass after 42 days

  20. Removal performance of elemental mercury by low-cost adsorbents prepared through facile methods of carbonisation and activation of coconut husk.

    PubMed

    Johari, Khairiraihanna; Alias, Afidatul Shazwani; Saman, Norasikin; Song, Shiow Tien; Mat, Hanapi

    2015-01-01

    The preparation of chars and activated carbon as low-cost elemental mercury adsorbents was carried out through the carbonisation of coconut husk (pith and fibre) and the activation of chars with potassium hydroxide (KOH), respectively. The synthesised adsorbents were characterised by using scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption analysis. The elemental mercury removal performance was measured using a conventional flow type packed-bed adsorber. The physical and chemical properties of the adsorbents changed as a result of the carbonisation and activation process, hence affecting on the extent of elemental mercury adsorption. The highest elemental mercury (Hg°) adsorption capacity was obtained for the CP-CHAR (3142.57 µg g(-1)), which significantly outperformed the pristine and activated carbon adsorbents, as well as higher than some adsorbents reported in the literature.

  1. Alkenyl/thiol-derived metal-organic frameworks (MOFs) by means of postsynthetic modification for effective mercury adsorption.

    PubMed

    Liu, Tao; Che, Jin-Xin; Hu, Yong-Zhou; Dong, Xiao-Wu; Liu, Xin-Yuan; Che, Chi-Ming

    2014-10-20

    The synthesis of new functionally diverse alkenyl-derived Cr-MIL-101s (MIL=material of Institute Lavoisier) was realized by a novel and convenient postsynthetic modification (PSM) protocol by means of the carbon-carbon bond-forming Mizoroki-Heck reaction. The new PSM protocol demonstrates a broad scope of substrates with excellent tolerance of functionality under mild reaction conditions. Moreover, a new metal-organic framework (MOF) that bears both alkenyl and thiol side chains prepared by means of the tandem PSM method has shown excellent adsorbent ability in removing mercury ions from water.

  2. Superb adsorption capacity of hierarchical calcined Ni/Mg/Al layered double hydroxides for Congo red and Cr(VI) ions.

    PubMed

    Lei, Chunsheng; Zhu, Xiaofeng; Zhu, Bicheng; Jiang, Chuanjia; Le, Yao; Yu, Jiaguo

    2017-01-05

    The preparation of hierarchical porous materials as catalysts and sorbents has attracted much attention in the field of environmental pollution control. Herein, Ni/Mg/Al layered double hydroxides (NMA-LDHs) hierarchical flower-like hollow microspheres were synthesized by a hydrothermal method. After the NMA-LDHs was calcined at 600°C, NMA-LDHs transformed into Ni/Mg/Al layered double oxides (NMA-LDOs), which maintained the hierarchical flower-like hollow structure. The crystal phase, morphology, and microstructure of the as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy elemental mapping, Fourier transform infrared spectroscopy, and nitrogen adsorption-desorption methods. Both the calcined and non-calcined NMA-LDHs were examined for their performance to remove Congo red (CR) and hexavalent chromium (Cr(VI)) ions in aqueous solution. The maximum monolayer adsorption capacities of CR and Cr(VI) ions over the NMA-LDOs sample were 1250 and 103.4mg/g at 30°C, respectively. Thermodynamic studies indicated that the adsorption process was endothermic in nature. In addition, the addition of coexisting anions negatively influenced the adsorption capacity of Cr(VI) ions, in the following order: CO3(2-)>SO4(2-)>H2PO4(-)>Cl(-). This work will provide new insight into the design and fabrication of advanced adsorption materials for water pollutant removal.

  3. Crystal Face Distributions and Surface Site Densities of Two Synthetic Goethites: Implications for Adsorption Capacities as a Function of Particle Size.

    PubMed

    Livi, Kenneth J T; Villalobos, Mario; Leary, Rowan; Varela, Maria; Barnard, Jon; Villacís-García, Milton; Zanella, Rodolfo; Goodridge, Anna; Midgley, Paul

    2017-09-12

    Two synthetic goethites of varying crystal size distributions were analyzed by BET, conventional TEM, cryo-TEM, atomic resolution STEM and HRTEM, and electron tomography in order to determine the effects of crystal size, shape, and atomic scale surface roughness on their adsorption capacities. The two samples were determined by BET to have very different site densities based on Cr(VI) adsorption experiments. Model specific surface areas generated from TEM observations showed that, based on size and shape, there should be little difference in their adsorption capacities. Electron tomography revealed that both samples crystallized with an asymmetric {101} tablet habit. STEM and HRTEM images showed a significant increase in atomic-scale surface roughness of the larger goethite. This difference in roughness was quantified based on measurements of relative abundances of crystal faces {101} and {201} for the two goethites, and a reactive surface site density was calculated for each goethite. Singly coordinated sites on face {210} are 2.5 more dense than on face {101}, and the larger goethite showed an average total of 36% {210} as compared to 14% for the smaller goethite. This difference explains the considerably larger adsorption capacitiy of the larger goethite vs the smaller sample and points toward the necessity of knowing the atomic scale surface structure in predicting mineral adsorption processes.

  4. In Situ Immobilization on the Silica Gel Surface and Adsorption Capacity of Poly[ N-(4-carboxyphenyl)methacrylamide] on Toxic Metal Ions

    NASA Astrophysics Data System (ADS)

    Yanovska, Elina; Savchenko, Irina; Sternik, Dariusz; Kychkiruk, Olga; Ol'khovik, Lidiya; Buriachenko, Iana

    2017-04-01

    In situ immobilization of poly[ N-(4-carboxyphenyl)methacrylamide] has been performed on silica gel surface. Infrared (IR) and mass spectroscopies as well as thermogravimetry (TG) analysis have been used to elucidate the structure of immobilized polymer. An adsorption capacity of the synthesized composite towards Cu(II), Pb(II), Mn(II), Fe(III), Co(II), and Ni(II) ions has been estimated. Adsorption activity to microquantities of Pb(II), Cu(II), and Ni(II) in a neutral aqueous medium has been observed.

  5. A study of the alumina-silica gel adsorbent for the removal of silicic acid from geothermal water: increase in adsorption capacity of the adsorbent due to formation of amorphous aluminosilicate by adsorption of silicic acid.

    PubMed

    Yokoyama, Takushi; Ueda, Akira; Kato, Koichi; Mogi, Katsumi; Matsuo, Shorin

    2002-08-01

    Two kinds of adsorbents (Si adsorbent and Al adsorbent) for the removal of silicic acid from geothermal water to retard the formation of silica scales were prepared using silicic acid contained in geothermal water. The Si adsorbent was prepared by evaporating geothermal water, and the Al adsorbent was prepared by evaporating geothermal water after the addition of aluminum chloride. The specific surface area of the Si adsorbent was small and it's adsorption capacity of silicic acid was low. Although the specific surface area of the Al adsorbent was also small, it was significantly increased by the adsorption of silicic acid and it's adsorption capacity was high. Based on the change in the local structure of aluminum ion by the adsorption of silicic acid, the Al adsorbent was considered to be silica particles covered with crystalline aluminum hydroxide. Moreover, it was concluded that the increase in the specific surface area of the Al adsorbent and the decrease in the zeta potential were due to the formation of an amorphous aluminosilicate with a large surface area and a negative charge (one 4-coordinated Al) by the reaction between aluminum ions and silicic acids.

  6. Fourier transform infra-red (FTIR) spectroscopy investigation, dose effect, kinetics and adsorption capacity of phosphate from aqueous solution onto laterite and sandstone.

    PubMed

    Coulibaly, Lassina Sandotin; Akpo, Sylvain Kouakou; Yvon, Jacques; Coulibaly, Lacina

    2016-12-01

    Environmental pollution by phosphate in developing countries is growing with extensive and diffuse pollution. Solving these problem with intensive technologies is very expensive. Using natural sorbent such as laterite and sandstone could be a solution. The main objective of the study is to evaluate the P-removal efficiency of these materials under various solution properties. Laterite and sandstone used mainly contain very high levels of finely grained iron and aluminum oxy-hydroxides and diverse dioctahedral clays. Phosphate adsorption tests were carried out using crushed laterite and sandstone. Optimal doses and pH effects on phosphate adsorption were studied with a potassium hydrogeno-phosphate solution of 5 mg/L at 30 °C. The main results were that the optimal dosage is 15 and 20 mg/L respectively for laterite and sandstone. The phosphate adsorptions efficiency of laterite and sandstone are pH-dependent, they increase when the pH grows up to the Point of Zero Charge (PZC) and slowly decrease beyond. The adsorption capacities of the materials also increase proportionally with the initial phosphate concentration. The pseudo-second-order successfully described the kinetics of the phosphate adsorption on the two adsorbents. With this model, the adsorption capacity values are obtained, which give an idea of the maximum phosphate uptake that the laterite and sandstone could achieve. The changes on the FTIR spectra of raw materials and phosphate adsorbed material confirm the mechanism of chemisorptions. Considering the above, laterite and sandstone could be used as efficient and cheap adsorbent for the removal of phosphate in aqueous solution. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. A one-step thermal decomposition method to prepare anatase TiO2 nanosheets with improved adsorption capacities and enhanced photocatalytic activities

    NASA Astrophysics Data System (ADS)

    Li, Wenting; Shang, Chunli; Li, Xue

    2015-12-01

    Anatase TiO2 nanosheets (NSs) with high surface area have been prepared via a one-step thermal decomposition of titanium tetraisopropoxide (TTIP) in oleylamine (OM), and their adsorption capacities and photocatalytic activities are investigated by using methylene blue (MB) and methyl orange (MO) as model pollutants. During the synthesis procedure, only one type of surfactant, oleylamine (OM), is used as capping agents and no other solvents are added. Structure and properties of the TiO2 NSs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption analysis, UV-vis spectrum, X-ray photoelectron spectroscopy (XPS) and Photoluminescence (PL) methods. The results indicate that the TiO2 NSs possess high surface area up to 378 m2 g-1. The concentration of capping agents is found to be a key factor controlling the morphology and crystalline structure of the product. Adsorption and photodegradation experiments reveal that the prepared TiO2 NSs possess high adsorption capacities of model pollutants MB and high photocatalytic activity, showing that TiO2 NSs can be used as efficient pollutant adsorbents and photocatalytic degradation catalysts of MB in wastewater treatment.

  8. Combined electron-beam and adsorption purification of water from mercury and chromium using materials of vegetable origin as sorbents

    NASA Astrophysics Data System (ADS)

    Ponomarev, A. V.; Bludenko, A. V.; Makarov, I. E.; Pikaev, A. K.; Kyung Kim, Duk; Kim, Yuri; Han, Bumsoo

    1997-04-01

    Combined electron-beam and adsorption method of purification of water from Hg(II) and Cr(VI) using materials of vegetable origin as sorbents was developed. It consists in the addition of materials of vegetable origin (e.g. cellulose, carboxymethyl cellulose, starch, and wheat flour) into water, subsequent electron-beam irradiation, sedimentation and filtration of additives with captured Hg(II) or Cr(VI). The method is based on the synergistic effect of the combined action of irradiation and sorbent. The best results were obtained with the wheat flour. For example, the addition of 25 mg/I of the flour to the water containing 1 mg/I Hg(II) and irradiation with dose 1.1 kGy upon bubbling inert gas through the system led to the 98% removal of the pollutant. The possible mechanism of the processes causing the purification of water is discussed.

  9. Mercury emissions from coal combustion: modeling and comparison of Hg capture in a fabric filter versus an electrostatic precipitator.

    PubMed

    Scala, Fabrizio; Clack, Herek L

    2008-04-01

    Mercury emissions from coal combustion must be reduced, in response to new air quality regulations in the U.S. Although the most mature control technology is adsorption across a dust cake of powdered sorbent in a fabric filter (FF), most particulate control in the U.S. associated with coal combustion takes the form of electrostatic precipitation (ESP). Using recently developed models of mercury adsorption within an ESP and within a growing sorbent bed in a FF, parallel analyses of elemental mercury (Hg(0)) uptake have been conducted. The results show little difference between an ESP and a FF in absolute mercury removal for a low-capacity sorbent, with a high-capacity sorbent achieving better performance in the FF. Comparisons of fractional mercury uptake per-unit-pressure-drop provide a means for incorporating and comparing the impact of the much greater pressure drop of a FF as compared to an ESP. On a per-unit-pressure-drop basis, mercury uptake within an ESP exhibited better performance, particularly for the low-capacity sorbent and high mass loadings of both sorbents.

  10. Removal of mercury from an alumina refinery aqueous stream.

    PubMed

    Mullett, Mark; Tardio, James; Bhargava, Suresh; Dobbs, Charles

    2007-06-01

    Digestion condensate is formed as a by-product of the alumina refinery digestion process. The solution exhibits a high pH and is chemically reducing, containing many volatile species such as water, volatile organics, ammonia, and mercury. Because digestion condensate is chemically unique, an innovative approach was required to investigate mercury removal. The mercury capacity and adsorption kinetics were investigated using a number of materials including gold, silver and sulphur impregnated silica and a silver impregnated carbon. The results were compared to commercial sorbents, including extruded and powdered virgin activated carbons and a sulphur impregnated mineral. Nano-gold supported on silica (88% removal under batch conditions and 95% removal under flow conditions) and powdered activated carbon (91% under batch conditions and 98% removal under flow conditions) were the most effective materials investigated. The silver and sulphur impregnated materials were unstable in digestion condensate under the test conditions used.

  11. Sol-gel synthesized adsorbents for mercury(II), chromium(III) and cobalt(II) separations

    NASA Astrophysics Data System (ADS)

    Nam, Kwan-Hyun

    Novel organo-ceramic adsorbents are synthesized and characterized for mercury(II), chromium(III) and cobalt(II) separations from aqueous streams. Mercury(II) adsorption on thiol functional adsorbents (SOL-AD-IV) is studied for two systems: (1) coal-fired utility plant scrubber water, and (2) acidic nuclear wastes. To exemplify the removal of mercury from these systems, simulants are prepared and used. Results show that the mercury adsorption capacity is higher than reported in the literature. In addition, the adsorbent exhibits high adsorption capacity even at 4 M HNO3. In column operation, flow rates as high as 1100 BV/h could be employed with effluent concentrations reaching below 0.06 mug/L. This adsorbent is found to exhibit superior mercury adsorption characteristics with a demonstrated long life cycle. Chromium(III) and cobalt(II) adsorption is evaluated using phosphonic acid (SOL-PHONIC) and phosphinic acid (SOL-PHINIC) functional adsorbents synthesized via sol-gel processing by co-condensation of clusters of functional precursor (FPS) and cross-linking (CA) silanes. Nuclear magnetic resonance (NMR) spectroscopy is used to examine the evolution of oligomeric species with hydrolysis and condensation reaction times. The effects of both the FPS and CA oligomeric species on the physicochemical properties of the resulting adsorbent materials are evaluated and explained in terms of structural and adsorption capacity characteristics. The adsorbents are further characterized by solid-state NMR spectroscopy to elucidate the incorporation of the FPS and the nature of the functional groups in the adsorbent matrix. SOL-PHONIC is employed for the removal of chromium, and both SOL-PHONIC and SOL-PHINIC are employed for the removal of cobalt. Results show that chromium and cobalt adsorptions are solution pH dependent. Cobalt adsorption tests evaluated using the two adsorbents show that SOL-PHONIC exhibits a higher selectivity towards cobalt over nickel. The adsorption

  12. Surfactant-free synthesis of octahedral ZnO/ZnFe2O4 heterostructure with ultrahigh and selective adsorption capacity of malachite green

    PubMed Central

    Liu, Jue; Zeng, Min; Yu, Ronghai

    2016-01-01

    A new octahedral ZnO/ZnFe2O4 heterostructure has been fabricated through a facile surfactant-free solvothermal method followed by thermal treatment. It exhibits a record-high adsorption capacity (up to 4983.0 mg·g−1) of malachite green (MG), which is a potentially harmful dye in prevalence and should be removed from wastewater and other aqueous solutions before discharging into the environment. The octahedral ZnO/ZnFe2O4 heterostructure also demonstrates strong selective adsorption towards MG from two kinds of mixed solutions: MG/methyl orange (MO) and MG/rhodamine B (RhB) mixtures, indicating its promise in water treatment. PMID:27142194

  13. Ultrasond-assisted synthesis of Fe3O4/SiO2 core/shell with enhanced adsorption capacity for diazinon removal

    NASA Astrophysics Data System (ADS)

    Farmany, Abbas; Mortazavi, Seyede Shima; Mahdavi, Hossein

    2016-10-01

    Fe3O4/SiO2 core/shell nanocrystals were synthesized by ultrasond-assisted procedure. The core/shell nanocrystals were characterized using XRD, FT-IR spectroscopy, SEM and BET. The BET analysis confirmed that iron oxide nanocrystal with the surface area of 208.0 m2/g can be used as an excellent adsorbent for organic and inorganic pollutants. The core/shell nanocrystal was used as an adsorbent for removal of insecticide O,O-diethyl-O[2-isopropyl-6-methylpyridimidinyl] phosphorothioate (diazinon). In continue the influence of different parameters such as pH, adsorbent dosage and shaking time on the adsorption capacity were studied. The experimental data were fitted well with the pseudo-second-order kinetic model (R2=0.9706). The adsorption isotherm was described well by Langmuir isotherm.

  14. Surfactant-free synthesis of octahedral ZnO/ZnFe2O4 heterostructure with ultrahigh and selective adsorption capacity of malachite green

    NASA Astrophysics Data System (ADS)

    Liu, Jue; Zeng, Min; Yu, Ronghai

    2016-05-01

    A new octahedral ZnO/ZnFe2O4 heterostructure has been fabricated through a facile surfactant-free solvothermal method followed by thermal treatment. It exhibits a record-high adsorption capacity (up to 4983.0 mg·g‑1) of malachite green (MG), which is a potentially harmful dye in prevalence and should be removed from wastewater and other aqueous solutions before discharging into the environment. The octahedral ZnO/ZnFe2O4 heterostructure also demonstrates strong selective adsorption towards MG from two kinds of mixed solutions: MG/methyl orange (MO) and MG/rhodamine B (RhB) mixtures, indicating its promise in water treatment.

  15. Methane and carbon dioxide adsorption capacity of bituminous coals from the Ostrava-Karvina Coal District, Upper Silesian Basin, Czech Republic

    NASA Astrophysics Data System (ADS)

    Weniger, P.; Busch, A.; Krooss, B. M.; Francu, J.; Francu, E.

    2009-04-01

    In the context of a joint Czech-German project, experimental and analytical methods are being applied to improve the understanding of compositional variation of coal-related gas in the SW part of the Upper Silesian Basin (Czech Republic). According to present understanding, the gas composition is controlled by generation (thermal vs. microbial), migration and adsorption/desorption processes. In particular the effects of the sorption processes on the chemical and isotopic composition of coal gases are only poorly explored. During the first stage of this project, the gas adsorption capacity has been determined for coal samples representing the paralic Ostrava Formation (Namurian A) and the limnic Karviná Formation (Namurian B-C). For this purpose, high pressure adsorption isotherms have been measured for methane and carbon dioxide on medium and low volatile bituminous coal (VRr 1.2-1.8%) from the production face of two collieries in the study area. Adsorption isotherms have been measured for pressures up to 25 MPa for CO2 and up to 17 MPa for methane at 20˚ C and 45˚ C. Isotherms were measured on dry, moisture-equilibrated and "as received" samples (moisture content: 0.5-1.7%, mineral-matter-free) using a manometric method. Sorption capacities for CH4 at 45˚ C ranged from 18 to 27 Std. cm3/g (0.7 to 1.1 mmol/g) coal, dry ash-free (daf), showing an increase of sorption capacity with increasing coal rank. For CO2, sorption capacities were generally higher than for methane, ranging from 35-40 Std. cm3/g (1.4-1.7 mmol/g) coal (daf). Equilibrium moisture contents, determined by a modified ASTM method, were significantly higher than the "as received" moisture. Sorption capacities measured on moisture-equilibrated samples were generally lower than those measured on dry or "as received" samples. Methane excess sorption isotherms show a type I Langmuir form and could be approximated using the Langmuir function. Excess sorption isotherms for CO2 show a decrease in

  16. Stabilization/solidification (S/S) of mercury-contaminated hazardous wastes using thiol-functionalized zeolite and Portland cement.

    PubMed

    Zhang, Xin-Yan; Wang, Qi-Chao; Zhang, Shao-Qing; Sun, Xiao-Jing; Zhang, Zhong-Sheng

    2009-09-15

    Stabilization/solidification (S/S) of mercury-containing solid wastes using thiol-functionalized zeolite and cement was investigated in this study. The thiol-functionalized zeolite (TFZ) used in the study was obtained by grafting the thiol group (-SH) to the natural clinoptilolite zeolites, and the mercury adsorption by TFZ was investigated. TFZ was used to stabilize mercury in solid wastes, and then the stabilized wastes were subjected to cement solidification to test the effectiveness of the whole S/S process. The results show that TFZ has a high level of -SH content (0.562 mmol g(-1)) and the adsorption of mercury by TFZ conform to the Freundlich adsorption isotherm. The mercury adsorption capacity is greatly enhanced upon thiol grafting, the maximum of which is increased from 0.041 mmol Hg g(-1) to 0.445 mmol Hg g(-1). TFZ is found to be effective in stabilizing Hg in the waste surrogate. In the stabilization process, the optimum pH for the stabilization reaction is about 5.0. The optimum TFZ dosage is about 5% and the optimum cement dosage is about 100%. Though Cl(-) and PO(4)(3-) have negative effects on mercury adsorption by TFZ, the Portland cement solidification of TFZ stabilized surrogates containing 1000 mg Hg/kg can successfully pass the TCLP leaching test. It can be concluded that the stabilization/solidification process using TFZ and Portland cement is an effective technology to treat and dispose mercury-containing wastes.

  17. High adsorptive γ-AlOOH(boehmite)@SiO2/Fe3O4 porous magnetic microspheres for detection of toxic metal ions in drinking water.

    PubMed

    Wei, Yan; Yang, Ran; Zhang, Yong-Xing; Wang, Lun; Liu, Jin-Huai; Huang, Xing-Jiu

    2011-10-21

    γ-AlOOH(boehmite)@SiO(2)/Fe(3)O(4) porous magnetic microspheres with high adsorption capacity toward heavy metal ions were found to be useful for the simultaneous and selective electrochemical detection of five metal ions, such as ultratrace zinc(II), cadmium(II), lead(II), copper(II), and mercury(II), in drinking water.

  18. High-efficient mercury removal from environmental water samples using di-thio grafted on magnetic mesoporous silica nanoparticles.

    PubMed

    Mehdinia, Ali; Akbari, Maryam; Baradaran Kayyal, Tohid; Azad, Mohammad

    2015-02-01

    In this work, magnetic di-thio functionalized mesoporous silica nanoparticles (DT-MCM-41) were prepared by grafting dithiocarbamate groups within the channels of magnetic mesoporous silica nanocomposites. The functionalized nanoparticles exhibited proper magnetic behavior. They were easily separated from the aqueous solution by applying an external magnetic field. The results indicated that the functionalized nanoparticles had a potential for high-efficient removal of Hg(2+) in environmental samples. The maximum adsorption capacity of the sorbent was 538.9 mg g(-1), and it took about 10 min to achieve the equilibrium adsorption. The resulted adsorption capacity was higher than similar works for adsorption of mercury. It can be due to the presence of di-thio and amine active groups in the structure of sorbent. The special properties of MCM-41 like large surface area and high porosity also provided a facile accessibility of the mercury ions into the ligand sites. The complete removal of mercury ions was attained with dithiocarbamate groups in a wide range of mercury concentrations. The recovery studies were also applied for the river water, seawater, and wastewater samples, and the values were over of 97 %.

  19. Adsorption of Hg(II) from aqueous solutions using TiO2 and titanate nanotube adsorbents

    NASA Astrophysics Data System (ADS)

    López-Muñoz, María-José; Arencibia, Amaya; Cerro, Luis; Pascual, Raquel; Melgar, Álvaro

    2016-03-01

    Titania and titanate nanotubes were evaluated as adsorbents for the removal of Hg(II) from aqueous solution. Commercial titanium dioxide (TiO2-P25, Evonik), a synthesized anatase sample obtained by the sol-gel method (TiO2-SG) and titanate nanotubes (TNT) prepared via hydrothermal treatment were compared. Mercury adsorption was analysed by kinetic and equilibrium experiments, studying the influence of pH and the type of adsorbents. The kinetics of Hg(II) adsorption on titania and titanate nanotubes could be well described by the pseudo-second order model. It was found that the process is generally fast with small differences between adsorbents, which cannot be explained by their dissimilarities in textural properties. Equilibrium isotherm data were best fitted with the Sips isotherm model. The maximum adsorption capacities of Hg(II) were achieved with titanate nanotubes sample, whereas between both titania samples, TiO2-SG exhibited the highest mercury uptake. For all adsorbents, adsorption capacities were enhanced as pH was increased, achieving at pH 10 Hg(II) adsorption capacities of 100, 121, and 140 mg g-1 for TiO2-P25, TiO2-SG, and TNT, respectively. Differences between samples were discussed in terms of their crystalline phase composition and chemical nature of both, mercury species and surface active sites.

  20. PREDICTING THE ADSORPTION CAPACITY OF ACTIVATED CARBON FOR EMERGING ORGANIC CONTAMINANTS FROM FUNDAMENTAL ADSORBENT AND ADSORBATE PROPERTIES - PRESENTATION

    EPA Science Inventory

    A quantitative structure-property relationship (QSPR) was developed and combined with the Polanyi-Dubinin-Manes model to predict adsorption isotherms of emerging contaminants on activated carbons with a wide range of physico-chemical properties. Affinity coefficients (βl

  1. Effect of non-toxic mercury, zinc or cadmium pretreatment on the capacity of human monocytes to undergo lipopolysaccharide-induced activation

    PubMed Central

    Koropatnick, J; Zalups, R K

    1997-01-01

    Metal salts can inhibit cell activity through direct toxicity to critical cellular molecules and structures. On the other hand, they can also change cell behaviour by inducing specific genes (including genes encoding members of the metallothionein [MT] gene family). Therefore, transition metals may affect cell functions either by acting as a toxin, or by transmitting or influencing signals controlling gene expression.To explore the latter possibility, we measured the ability of low, non-toxic metal pretreatment to alter immune cell behaviour. We previously found that pretreatment of human monocytes with zinc induces metallothionein gene expression and alters their capacity to undergo a bacterial lipopolysaccharide-induced respiratory burst. We showed here that cadmium and mercury salts, at concentrations that exert no discernible toxicity, inhibit activation of human monocytic leukemia (THP-1) cells. CdCl2 1 μM, ZnCl2 20–40 μM or HgCl2 2 μM pretreatment for 20 h induced MT-2 mRNA and total MT protein accumulation and had no effect on proliferation potential or metabolic activity, but significantly inhibited the ability of subsequent lipopolysaccharide treatment to induce the oxidative burst, increased adhesion to plastic, and MT-2 and interleukin-1β (IL-1β) mRNA accumulation.The phenomenon of metal-induced suppression of monocyte activation, at metal concentrations that have no effect on cell viability, has important implications for assessment of acceptable levels of human exposure to cadmium, zinc and mercury. PMID:9138684

  2. LabVIEW-based sequential-injection analysis system for the determination of trace metals by square-wave anodic and adsorptive stripping voltammetry on mercury-film electrodes.

    PubMed

    Economou, Anastasios; Voulgaropoulos, Anastasios

    2003-01-01

    The development of a dedicated automated sequential-injection analysis apparatus for anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (AdSV) is reported. The instrument comprised a peristaltic pump, a multiposition selector valve and a home-made potentiostat and used a mercury-film electrode as the working electrodes in a thin-layer electrochemical detector. Programming of the experimental sequence was performed in LabVIEW 5.1. The sequence of operations included formation of the mercury film, electrolytic or adsorptive accumulation of the analyte on the electrode surface, recording of the voltammetric current-potential response, and cleaning of the electrode. The stripping step was carried out by applying a square-wave (SW) potential-time excitation signal to the working electrode. The instrument allowed unattended operation since multiple-step sequences could be readily implemented through the purpose-built software. The utility of the analyser was tested for the determination of copper(II), cadmium(II), lead(II) and zinc(II) by SWASV and of nickel(II), cobalt(II) and uranium(VI) by SWAdSV.

  3. Synthesis and evaluation of a thiourea-modified chitosan derivative applied for adsorption of Hg(II) from synthetic wastewater.

    PubMed

    Wang, Lin; Xing, Ronge; Liu, Song; Cai, Shengbao; Yu, Huahua; Feng, Jinhua; Li, Rongfeng; Li, Pengcheng

    2010-06-01

    In this work, a thiourea-modified chitosan derivative (TMCD) was synthesized through two steps, O-carboxymethylated first and then modified by a polymeric Schiff's base of thiourea/glutaraldehyde. The adsorption behavior of mercury (II) ions onto TMCD was investigated through batch method. The maximum adsorption capacity for Hg(II) was found to be 6.29 mmol/g at pH 5.0 and both kinetic and thermodynamic parameters of the adsorption process were obtained. The results indicated that adsorption process was spontaneous exothermic reaction and kinetically followed pseudo-second-order model. The adsorption experiments also demonstrated TMCD had high adsorption selectivity towards Hg(II) ions when coexisted with Cu(II), Zn(II), Cd(II) and Ca(II) in solution and it could be easily regenerated and efficiently reused.

  4. Surface catalyzed mercury transformation reactions

    NASA Astrophysics Data System (ADS)

    Varanasi, Patanjali

    /m 3 using a diffusion tube as the source of Hg0(g). All experiments were conducted using 4% O2 in nitrogen mix as a reaction gas, and other reactants (HCl, H2O and SO2, NO 2, Br2) were added as required. The fixed bed reactor was operated over a temperature range of 200 to 400°C. In each experiment, the reactor effluent was analyzed using the modified Ontario-Hydro method. After each experiment, fly ash particles were also analyzed for mercury. The results show that the ability of fly ash to adsorb and/or oxidize mercury is primarily dependent on its carbon, iron and calcium content. There can be either one or more than one key component at a particular temperature and flue gas condition. Surface area played a secondary role in effecting the mercury transformations when compared to the concentration of the key component in the fly ash. Amount carbon and surface area played a key important role in the adsorption of mercury. Increased concentration of gases in the flue gas other than oxygen and nitrogen caused decreased the amount of mercury adsorbed on carbon surface. Mercury adsorption by iron oxide primarily depended on the crystalline structure of iron oxide. alpha-iron oxide had no effect on mercury adsorption or oxidation under most of the flue gas conditions, but gamma-iron oxide adsorbed mercury under most of the flue gas conditions. Bromine is a very good oxidizing agent for mercury. But in the presence of calcium oxide containing fly ashes, all the oxidized mercury would be reduced to elemental form. Among the catalysts, it was observed that presence of free lattice chlorine in the catalyst was very important for the oxidation of mercury. But instead of using the catalyst alone, using it along with carbon may better serve the purpose by providing the adsorption surface for mercury and also some extra surface area for the reaction to occur (especially for fly ashes with low surface area).

  5. The water-based synthesis of chemically stable Zr-based MOFs using pyridine-containing ligands and their exceptionally high adsorption capacity for iodine.

    PubMed

    Wang, Zhe; Huang, Ying; Yang, Jian; Li, Yongsheng; Zhuang, Qixin; Gu, Jinlou

    2017-06-13

    The primary pollutant, radioactive iodine (I2), has become a worldwide concern due to its serious ill effects of radiotoxicity on human health. Therefore, it is of great significance to develop novel adsorbents for effectively eliminating I2 from nuclear waste. Herein, we reported a Zr-based MOF adsorbent constructed by utilizing pyridine-containing pyridine-dicarboxylic acid (PYDC) as organic ligands (UiO-66-PYDC) as well as active sites for the efficient removal of I2. UiO-66-PYDC MOFs were synthesized by a hydrothermal strategy and featured good chemical and thermal stabilities, endowing them with the ability to work in harsh environments. The abundant and inherent pyridine moieties in the developed adsorbent worked as active adsorption sites to capture I2. The correlation between the most significant parameters such as the contact time, adsorbate concentration, and reusability was optimized, and the interaction mechanism between I2 and UiO-66-PYDC was investigated in detail. As for the current adsorbent, a pseudo-second order rate equation was used to explain the removal kinetics, and the Langmuir model exhibited a better fit to the adsorption isotherm than the Freundlich model. Thanks to the strong affinity of PYDC ligands to I2 and high porosity, the adsorption capacities of UiO-66-PYDC for I2 could reach as high as 1250 mg g(-1), which was much higher than those of many other reported MOFs. Additionally, the UiO-66-PYDC MOFs exhibited excellent renewable adsorption properties, prefiguring their great promise as green adsorbents for I2 removal in nuclear waste management.

  6. Granular activated carbon adsorption of organic micro-pollutants in drinking water and treated wastewater--Aligning breakthrough curves and capacities.

    PubMed

    Zietzschmann, Frederik; Stützer, Christian; Jekel, Martin

    2016-04-01

    Small-scale granular activated carbon (GAC) tests for the adsorption of organic micro-pollutants (OMP) were conducted with drinking water and wastewater treatment plant (WWTP) effluent. In both waters, three influent OMP concentration levels were tested. As long as the influent OMP concentrations are below certain thresholds, the relative breakthrough behavior is not impacted in the respective water. Accordingly, the GAC capacity for OMP is directly proportional to the influent OMP concentration in the corresponding water. The differences between the OMP breakthrough curves in drinking water and WWTP effluent can be attributed to the concentrations of the low molecular weight acid and neutral (LMW) organics of the waters. Presenting the relative OMP concentrations (c/c0) over the specific throughput of the LMW organics (mg LMW organics/g GAC), the OMP breakthrough curves in drinking water and WWTP effluent superimpose each other. This superimposition can be further increased if the UV absorbance at 254 nm (UV254) of the LMW organics is considered. In contrast, using the specific throughput of the dissolved organic carbon (DOC) did not suffice to obtain superimposed breakthrough curves. Thus, the LMW organics are the major water constituent impacting OMP adsorption onto GAC. The results demonstrate that knowing the influent OMP and LMW organics concentrations (and UV254) of different waters, the OMP breakthroughs and GAC capacities corresponding to any water can be applied to all other waters. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Effect of immobilized amine density on cadmium(II) adsorption capacities for ethanediamine-modified magnetic poly-(glycidyl methacrylate) microspheres

    NASA Astrophysics Data System (ADS)

    Dong, Tingting; Yang, Liangrong; Pan, Feng; Xing, Huifang; Wang, Li; Yu, Jiemiao; Qu, Hongnan; Rong, Meng; Liu, Huizhou

    2017-04-01

    A series of ethanediamine (EDA) - modified magnetic poly-(glycidyl methacrylate) (m-PGMA-EDA)microspheres with different amine density were synthesized and their cadmium saturation adsorption capacities were examined. The results showed that the cadmium saturation adsorption capacity increased with the immobilized amine density. However, they did not show strong positive linear correlation in the whole range of amine density examined. The molar ratio of amine groups to the adsorbed cadmium decreased with the increase of amine density and eventually reached a minimum value about 4. It suggested that low immobilized amine density led to low coordination efficiency of the amine. It is hypothesized that the immobilized amine groups needed to be physically close enough to form stable amine-metal complex. When the amine density reached to a critical value 1.25 m mol m-2, stable amine-cadmium complex (4:1 N/Cd) was proposed to form. To illustrate the coordination mechanism (structure and number) of amine and Cd, FT-IR spectra of m-PGMA-EDA and m-PGMA-EDA-Cd , and X-ray photoelectron spectroscopy (XPS) of PGMA-EDA and PGMA-EDA-Cd were examined and analyzed.

  8. Effect of Heat Treatment on the Nitrogen Content and Its Role on the Carbon Dioxide Adsorption Capacity of Highly Ordered Mesoporous Carbon Nitride.

    PubMed

    Lakhi, Kripal S; Park, Dae-Hwan; Joseph, Stalin; Talapaneni, Siddulu N; Ravon, Ugo; Al-Bahily, Khalid; Vinu, Ajayan

    2017-03-02

    Mesoporous carbon nitrides (MCNs) with rod-shaped morphology and tunable nitrogen contents have been synthesized through a calcination-free method by using ethanol-washed mesoporous SBA-15 as templates at different carbonization temperatures. Carbon tetrachloride and ethylenediamine were used as the sources of carbon and nitrogen, respectively. The resulting MCN materials were characterized with low- and high-angle powder XRD, nitrogen adsorption, high-resolution (HR) SEM, HR-TEM, elemental analysis, X-ray photoelectron spectroscopy, and X-ray absorption near-edge structure techniques. The carbonization temperature plays a critical role in controlling not only the crystallinity, but also the nitrogen content and textural parameters of the samples, including specific surface area and specific pore volume. The nitrogen content of MCN decreases with a concomitant increase in specific surface area and specific pore volume, as well as the crystallinity of the samples, as the carbonization temperature is increased. The results also reveal that the structural order of the materials is retained, even after heat treatment at temperatures up to 900 °C with a significant reduction of the nitrogen content, but the structure is partially damaged at 1000 °C. The carbon dioxide adsorption capacity of these materials is not only dependent on the textural parameters, but also on the nitrogen content. The MCN prepared at 900 °C, which has an optimum BET surface area and nitrogen content, registers a carbon dioxide adsorption capacity of 20.1 mmol g(-1) at 273 K and 30 bar, which is much higher than that of mesoporous silica, MCN-1, activated carbon, and multiwalled carbon nanotubes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Hydrogen adsorption capacities of multi-walled boron nitride nanotubes and nanotube arrays: a grand canonical Monte Carlo study.

    PubMed

    Ahadi, Zohreh; Shadman, Muhammad; Yeganegi, Saeed; Asgari, Farid

    2012-07-01

    Hydrogen adsorption in multi-walled boron nitride nanotubes and their arrays was studied using grand canonical Monte Carlo simulation. The results show that hydrogen storage increases with tube diameter and the distance between the tubes in multi-walled boron nitride nanotube arrays. Also, triple-walled boron nitride nanotubes present the lowest level of hydrogen physisorption, double-walled boron nitride nanotubes adsorb hydrogen better when the diameter of the inner tube diameter is sufficiently large, and single-walled boron nitride nanotubes adsorb hydrogen well when the tube diameter is small enough. Boron nitride nanotube arrays adsorb hydrogen, but the percentage of adsorbed hydrogen (by weight) in boron nitride nanotube arrays is rather similar to that found in multi-walled boron nitride nanotubes. Also, when the Langmuir and Langmuir-Freundlich equations were fitted to the simulated data, it was found that multi-layer adsorptivity occurs more prominently as the number of walls and the tube diameter increase. However, in single-walled boron nitride nanotubes with a small diameter, the dominant mechanism is monolayer adsorptivity.

  10. Higher adsorption capacity of Spirulina platensis alga for Cr(VI) ions removal: parameter optimisation, equilibrium, kinetic and thermodynamic predictions.

    PubMed

    Gunasundari, Elumalai; Senthil Kumar, Ponnusamy

    2017-04-01

    This study discusses about the biosorption of Cr(VI) ion from aqueous solution using ultrasonic assisted Spirulina platensis (UASP). The prepared UASP biosorbent was characterised by Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer-Emmet-Teller, scanning electron spectroscopy and energy dispersive X-ray and thermogravimetric analyses. The optimum condition for the maximum removal of Cr(VI) ions for an initial concentration of 50 mg/l by UASP was measured as: adsorbent dose of 1 g/l, pH of 3.0, contact time of 30 min and temperature of 303 K. Adsorption isotherm, kinetics and thermodynamic parameters were calculated. Freundlich model provided the best results for the removal of Cr(VI) ions by UASP. The adsorption kinetics of Cr(VI) ions onto UASP showed that the pseudo-first-order model was well in line with the experimental data. In the thermodynamic study, the parameters like Gibb's free energy, enthalpy and entropy changes were evaluated. This result explains that the adsorption of Cr(VI) ions onto the UASP was exothermic and spontaneous in nature. Desorption of the biosorbent was done using different desorbing agents in which NaOH gave the best result. The prepared material showed higher affinity for the removal of Cr(VI) ions and this may be an alternative material to the existing commercial adsorbents.

  11. Mercury (II) removal from water by coconut shell based activated carbon: batch and column studies.

    PubMed

    Goel, Jyotsna; Kadirvelu, K; Rajagopal, C

    2004-02-01

    This study was undertaken to investigate adsorption behavior of Hg (II) from aqueous systems on activated carbon in static and dynamic mode by varying initial Hg (II) concentration, adsorbent dose and pH. Langmuir and Freundlich adsorption isotherm were applied to model the adsorption data. Removal of mercury obeyed the Langmuir and Freundlich adsorption isotherm models. The extent of removal of Hg (II) was found to be dependent on sorbent dose, pH and initial Hg (II) concentration. Mercury uptake increased from 72 to 100 percent with increasing pH from 2 to 10. A set of desorption studies was also performed for the metal ions with the aim of investigating the mechanism involved. Moreover, the competing effects of various ions like Pb (II) and Cu (II) is also described. The column capacity for a column diameter of 20 mm, bed height of 0.4 m, hydraulic loading rate of 7.5 m3 h(-1) m(-2) and a feed concentration of 3 mg l(-1) were found to be 3.02 mg g(-1). Breakthrough curves were plotted for the adsorption of mercury on the adsorbent using continuous-flow column operation by varying different operating parameters like hydraulic loading rate (3-10.5 m3 h(-1) m(-2)), bed height (0.3-0.5 m), and feed concentrations (2-6 mg l(-1)). The aim was to assess the effect of bed height, hydraulic loading rate and initial feed concentration on breakthrough time and adsorption capacity, which helped in ascertaining the practical applicability of the adsorbent. At the end an attempt has been made to develop empirical relationship from the data generated from column studies for designing the adsorption column, based on the Bohart-Adams model.

  12. Characterization of Fly Ash from Coal-Fired Power Plant and Their Properties of Mercury Retention

    NASA Astrophysics Data System (ADS)

    He, Ping; Jiang, Xiumin; Wu, Jiang; Pan, Weiguo; Ren, Jianxing

    2015-12-01

    Recent research has shown that fly ash may catalyze the oxidation of elemental mercury and facilitate its removal. However, the nature of mercury-fly ash interaction is still unknown, and the mechanism of mercury retention in fly ash needs to be investigated more thoroughly. In this work, a fly ash from a coal-fired power plant is used to characterize the inorganic and organic constituents and then evaluate its mercury retention capacities. The as-received fly ash sample is mechanically sieved to obtain five size fractions. Their characteristics are examined by loss on ignition (LOI), scanning electron microscope (SEM), energy dispersive X-ray detector (EDX), X-ray diffraction (XRD), and Raman spectra. The results show that the unburned carbon (UBC) content and UBC structural ordering decrease with a decreasing particle size for the five ashes. The morphologies of different size fractions of as-received fly ash change from the glass microspheres to irregular shapes as the particle size increases, but there is no correlation between particle size and mineralogical compositions in each size fraction. The adsorption experimental studies show that the mercury-retention capacity of fly ash depends on the particle size, UBC, and the type of inorganic constituents. Mercury retention of the types of sp2 carbon is similar to that of sp3 carbon.

  13. The effect of moisture on the methane adsorption capacity of shales: A study case in the eastern Qaidam Basin in China

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Yu, Qingchun

    2016-11-01

    This study investigated the effects of moisture on high-pressure methane adsorption in carboniferous shales from the Qaidam Basin, China. The shale characteristics, including the organic/inorganic compositions and pore structure (volume and surface) distribution, were obtained using various techniques. Gibbs adsorption measurements were performed over a pressure range up to 6 MPa and temperatures of 308.15 K on dry samples and moisture-equilibrated samples to analyze the correlations between organic/inorganic matter, pore structure, and moisture content on the methane sorption capacity. Compared to dry samples, the sorption capacity of wet samples (0.44-2.52% of water content) is reduced from 19.7 ± 5.3% to 36.1% ± 6.1%. Langmuir fitting is conducted to investigate moisture-dependent variations of adsorbed methane density, Langmuir pressure, and volume. By combining the pore volume and surface distribution analyses, our observations suggested that the main competition sites for CH4-H2O covered pores of approximately 2-7 nm, whereas the effective sites for methane and water were predominantly distributed within smaller (<4 nm) and larger pores (>10 nm), respectively. Regarding the compositional correlations, the impact of moisture on the amount of adsorbed methane shows a roughly linearly decreasing trend with increasing TOC content ranging from 0.62 to 2.88%, whereas the correlation between the moisture effect and various inorganic components is more complicated. Further fitting results indicate that illite/smectite mixed formations are closely related to the methane capacity, whereas the illite content show an evident connection to the pore structural (volume and surface) variations in the presence of moisture.

  14. Enhancement of p-nitrophenol adsorption capacity through N2-thermal-based treatment of activated carbons

    NASA Astrophysics Data System (ADS)

    Álvarez-Torrellas, S.; Martin-Martinez, M.; Gomes, H. T.; Ovejero, G.; García, J.

    2017-08-01

    In this work several activated carbons showing different textural and chemical properties were obtained by chemical and physical activation methods, using a lignocellulosic material (peach stones) as precursor. The activated carbon resulting from the chemical activation, namely as CAC, revealed the best textural properties (SBET = 1521 m2 g-1, pore volume = 0.90 cm3 g-1) and an acidic character. It was found that the activated carbon obtained at 300 °C (under air atmosphere, PAC_air), and those synthesized at 750 °C in presence of N2 flow with bubbling of water/12 M H3PO4 solution (PAC_N2(H2O)/PAC_N2(H3PO4)), respectively, revealed worse textural properties, compared to CAC. Two functionalization treatments, by using sulphuric acid at boiling temperature (PACS) and nitric acid-urea-N2 heating at 800 °C (PAC-NUT), were applied to PAC_air, in order to enhance the adsorption ability of the carbon material. Several techniques were carried out to characterize the physical and chemical properties of the obtained carbon materials. The modification treatments had influence on the carbon surface properties, since the nitric acid-urea-N2 heating treatment led to a carbon material with highly-improved properties (SBET = 679 m2 g-1, pHIEP = 5.3). Accordingly, the original and modified-carbon materials were tested as adsorbents to remove 4-nitrophenol (4-NP), assessing batch and fixed-bed column adsorption tests. PAC-NUT carbon offered the best adsorption behavior (qe = 234 mg g-1), showing a high ability for the removal of 4-NP from water.

  15. Al-promoted increase of surface area and adsorption capacity in ordered mesoporous silica materials with a cubic structure.

    PubMed

    Carmona, Daniel; Balas, Francisco; Mayoral, Álvaro; Luque, Rafael; Urriolabeitia, Esteban P; Santamaría, Jesús

    2011-12-07

    The structure of ordered mesoporous materials presenting a cubic structure undergoes a strong modification after adding aluminium alkoxides to the synthesis gel. As a result, an outstanding increase in the surface area and pore volume is observed, together with changes in the mesopore ordering. Hydrated aluminium species influence the chemical environment of the micelles during synthesis, which seems to induce the accumulation of stacking faults in the mesopore framework, and give rise to closer structural packing. The adsorption and release of ibuprofen as a test molecule correlates well with the textural changes observed.

  16. The Effect of Oxidation on the Surface Chemistry of Sulfur-Containing Carbons and their Arsine Adsorption Capacity

    DTIC Science & Technology

    2010-01-01

    hydrogen sulfide . Carbon 2004;42(3):469–76. Fig. 6 – Water adsorption isotherms of the samples studied. 1786 C A R B O N 4 8 ( 2 0 1 0 ) 1 7 7 9 –1 7 8...that oxygen- and sulfur-containing groups participate in arsine oxida- tion to arsenic tri- and pentoxide and/or in the formation of arsenic sulfides ...technological difficulties, arsine is also a powerful toxin susceptible to oxidation with a strong exothermic effect. Of all the methods to separate

  17. New V(IV)-based metal-organic framework having framework flexibility and high CO2 adsorption capacity.

    PubMed

    Liu, Ying-Ya; Couck, Sarah; Vandichel, Matthias; Grzywa, Maciej; Leus, Karen; Biswas, Shyam; Volkmer, Dirk; Gascon, Jorge; Kapteijn, Freek; Denayer, Joeri F M; Waroquier, Michel; Van Speybroeck, Veronique; Van Der Voort, Pascal

    2013-01-07

    A vanadium based metal-organic framework (MOF), VO(BPDC) (BPDC(2-) = biphenyl-4,4'-dicarboxylate), adopting an expanded MIL-47 structure type, has been synthesized via solvothermal and microwave methods. Its structural and gas/vapor sorption properties have been studied. This compound displays a distinct breathing effect toward certain adsorptives at workable temperatures. The sorption isotherms of CO(2) and CH(4) indicate a different sorption behavior at specific temperatures. In situ synchrotron X-ray powder diffraction measurements and molecular simulations have been utilized to characterize the structural transition. The experimental measurements clearly suggest the existence of both narrow pore and large pore forms. A free energy profile along the pore angle was computationally determined for the empty host framework. Apart from a regular large pore and a regular narrow pore form, an overstretched narrow pore form has also been found. Additionally, a variety of spectroscopic techniques combined with N(2) adsorption/desorption isotherms measured at 77 K demonstrate that the existence of the mixed oxidation states V(III)/V(IV) in the titled MOF structure compared to pure V(IV) increases the difficulty in triggering the flexibility of the framework.

  18. Magnetic properties and dye adsorption capacities of silica-hematite nanocomposites with well-defined structures prepared in surfactant solutions

    NASA Astrophysics Data System (ADS)

    You, Kyung-Eun; Park, Jun-Hwan; Kim, Young Chai; Oh, Seong-Geun

    2014-07-01

    Silica-hematite (α-Fe2O3) nanocomposites were synthesized by addition of aqueous solution containing ferrous ions (Fe2+), cetyltrimethylammonium bromide (CTAB) as a surfactant and tert-butanol (t-butanol) as a cosurfactant into colloidal silica solution. At alkaline atmosphere, silica surface with negative charges electrostatically attracts positively-charged iron hydroxide nuclei or particles which are stabilized by cationic CTAB molecules, and then silica-iron compound composites could be formed. Finally, the silica-hematite composite particles were obtained after calcination at 800 °C for 4 h. Through these processes, two types of composites having “core-shell type” or “decorated type” could be achieved. Morphology, BET surface area, crystallinity and magnetic properties of samples were analyzed by using TEM, BET, XRD and VSM, respectively. The “decorated type” composites had larger BET surface area and better magnetization. Also, to estimate the application in water treatment, adsorption properties of composites were studied through methylene blue (MB) adsorption which was characterized by UV-vis spectroscopy, involving collection of composites with neodymium magnet.

  19. Effect of cetyl trimethyl ammonium bromide concentration on structure, morphology and carbon dioxide adsorption capacity of calcium hydroxide based sorbents

    NASA Astrophysics Data System (ADS)

    Hlaing, Nwe Ni; Vignesh, K.; Sreekantan, Srimala; Pung, Swee-Yong; Hinode, Hirofumi; Kurniawan, Winarto; Othman, Radzali; Thant, Aye Aye; Mohamed, Abdul Rahman; Salim, Chris

    2016-02-01

    Calcium hydroxide (Ca(OH)2) has been proposed as an important material for industrial, architectural, and environmental applications. In this study, calcium acetate was used as a precursor and cetyl trimethyl ammonium bromide (CTAB) was used as a surfactant to synthesize Ca(OH)2 based adsorbents for carbon dioxide (CO2) capture. The effect of CTAB concentration (0.2-0.8 M) on the structure, morphology and CO2 adsorption performance of Ca(OH)2 was studied in detail. The synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), BET surfaced area and thermogravimetry-differential thermal analysis (TG-DTA) techniques. The phase purity, crystallite size, Brunauer-Emmett-Teller (BET) surface area and CO2 adsorption performance of Ca(OH)2 precursor adsorbents were significantly increased when the concentration of CTAB was increased. XRD results showed that pure Ca(OH)2 phase was obtained at the CTAB concentration of 0.8 M. TGA results exhibited that 0.8 M of CTAB-assisted Ca(OH)2 precursor adsorbent possessed a residual carbonation conversion of ∼56% after 10 cycles.

  20. Synthesis and Characterization of Novel Sulfur-Functionalized Silica Gels as Mercury Adsorbents

    NASA Astrophysics Data System (ADS)

    Johari, Khairiraihanna; Saman, Norasikin; Mat, Hanapi

    2014-03-01

    This paper describes the synthesis, functionalization, and characterization of silica gels as mercury adsorbents. The synthesis was carried out according to the modified Stöber method using tetraethyl orthosilicate [TEOS], 3-mercaptopropyl trimethoxysilane [MPTMS] and bis(triethoxysilylpropyl) tetrasulfide [BTEPST] as precursors. The functionalization was carried out via co-condensation and impregnation methods using MPTMS, BTESPT, elemental sulfur [ES], and carbon disulfide [CS2] as sulfur ligands. The choice of the sulfur ligands as precursors and functionalization agents was due to the existence of sulfur active groups in their molecular structures which were expected to have high affinity toward Hg(II) ions. The synthesized adsorbents were characterized by using scanning electron microscope, fourier transform infrared spectrophotometer, nitrogen adsorption/desorption, and energy dispersive X-ray diffractometer. The batch Hg(II) adsorption experiments were employed to evaluate the Hg(II) adsorption performances of the synthesized adsorbents under different pH values. The results revealed that the highest Hg(II) adsorption capacity was obtained for the SG-MPTMS(10) which was 47.83 mg/g at pH 8.5. In general, the existence of sulfur functional groups, especially MPTMS in the silica matrices, gave a significant enhancement of Hg(II) adsorption capacity and the sulfur functionalization via co-condensation method, which is potential as a superior approach in the mercury adsorbent synthesis.

  1. EVALUATING REGIONAL PREDICTIVE CAPACITY OF A PROCESS-BASED MERCURY EXPOSURE MODEL, REGIONAL-MERCURY CYCLING MODEL (R-MCM), APPLIED TO 91 VERMONT AND NEW HAMPSHIRE LAKES AND PONDS, USA

    EPA Science Inventory

    Regulatory agencies must develop fish consumption advisories for many lakes and rivers with limited resources. Process-based mathematical models are potentially valuable tools for developing regional fish advisories. The Regional Mercury Cycling model (R-MCM) was specifically d...

  2. EVALUATING REGIONAL PREDICTIVE CAPACITY OF A PROCESS-BASED MERCURY EXPOSURE MODEL, REGIONAL-MERCURY CYCLING MODEL (R-MCM), APPLIED TO 91 VERMONT AND NEW HAMPSHIRE LAKES AND PONDS, USA

    EPA Science Inventory

    Regulatory agencies must develop fish consumption advisories for many lakes and rivers with limited resources. Process-based mathematical models are potentially valuable tools for developing regional fish advisories. The Regional Mercury Cycling model (R-MCM) was specifically d...

  3. Fate and behaviour of copper and zinc in secondary biological wastewater treatment processes: I. Evaluation of biomass adsorption capacity.

    PubMed

    Crane, R S; Barton, P; Cartmell, E; Coulon, F; Hillis, P; Judd, S J; Santos, A; Stephenson, T; Lester, J N

    2010-06-01

    The current sources of copper and zinc in municipal wastewaters have been considered, and the changes in the concentrations and quantities of these two elements entering sewage treatment works over the last three decades have been calculated. The concentrations and quantities of the heavy metals cadmium, chromium, copper, mercury, nickel, lead and zinc, entering UK sewage treatment works, have been reduced by between 50% and 90% during this period. However, the reductions in copper and zinc appear to be at the lower end of these ranges and thus remain a cause for concern, particularly their concentrations in sewage effluents and their potential environmental impacts on receiving waters. Bench studies have been undertaken to predict removals by three types of biological wastewater treatment plants: trickling filters, conventional activated sludge and membrane bioreactors, to determine if any of these processes are more efficacious for the removal of these metals. These results suggest that, despite membrane bioreactor biomass achieving the lowest effluent suspended solids concentration and having the lowest effluent chemical oxygen demand, which is accepted as a surrogate measure of organic chemical chelating ability of the aqueous phase, they produce the highest effluent values for the two metals in this study (copper and zinc). Removals of zinc and copper in biological wastewater treatment processes are probably primarily determined by those factors influencing metal solubility in the biomass matrix.

  4. Importance of elemental mercury in lake sediments.

    PubMed

    Bouffard, Ariane; Amyot, Marc

    2009-02-01

    Mercury (Hg) redox changes in sediments are poorly studied and understood, even though they potentially control Hg availability for methylation and can alter sediment-water Hg exchange. Elemental Hg (Hg(0)) concentrations in sediments of two Canadian Shield lakes were assessed by thermodesorption. Hg(0) concentrations in sediments varied between 6.3 and 60.3 pg g(-1) (wet weight) which represented 7.4-28.4% of total mercury (HgT) concentration. Hg(0) concentrations were similar in both lakes. Hg(0) was rapidly adsorbed on sediments in controlled adsorption experiments and surface sediments sampled in summer had a stronger affinity for Hg(0) than deeper sediments and sediments sampled in fall. This adsorption was positively correlated to organic matter content and negatively related to particle grain size, pH and oxygen concentration in overlying water. This study demonstrates that Hg(0) is a prevalent species in sediments, but not in porewater, because of the high sorptive capacity of sediments towards Hg(0). Its potential availability towards Hg methylating bacteria remains to be determined.

  5. Application of a novel magnetic carbon nanotube adsorbent for removal of mercury from aqueous solutions.

    PubMed

    Homayoon, Farshid; Faghihian, Hossein; Torki, Firoozeh

    2017-04-01

    In this research, multiwall carbon nanotube was magnetized and subsequently functionalized by thiosemicarbazide. After characterization by FTIR, BET, SEM, EDAX, and VSM techniques, the magnetized adsorbent (multi-walled carbon nanotubes (MWCNTs)/Fe3O4) was used for removal of Hg(2+) from aqueous solutions and the experimental conditions were optimized. The adsorption capacity of 172.83 mg g(-1) was obtained at 25 °C and pH = 3 which was superior to the value obtained for initial multiwall carbon nanotube, magnetized sample, and many previously reported values. In the presence of Pb(+2) and Cd(+2), the adsorbent was selective towards mercury when their concentration was respectively below 50 and 100 mg L(-1). The adsorption process was kinetically fast and the equilibration was attained within 60 min with 69.5% of the capacity obtained within 10 min. The used adsorbent was regenerated by HNO3 solution, and the regenerated adsorbent retained 92% of its initial capacity. The magnetic sensitivity of the adsorbent allowed the simple separation of the used adsorbent from the solution by implying an appropriate external magnetic field. The adsorption data was well fitted to the Langmuir isotherm model, indicating homogeneous and monolayer adsorption of mercury by the adsorbent.

  6. MOFs for CO2 capture and separation from flue gas mixtures: the effect of multifunctional sites on their adsorption capacity and selectivity.

    PubMed

    Zhang, Zhijuan; Zhao, Yonggang; Gong, Qihan; Li, Zhong; Li, Jing

    2013-01-25

    Microporous metal-organic frameworks (MOFs) have attracted tremendous attention because of their versatile structures and tunable porosity that allow almost unlimited ways to improve their properties and optimize their functionality, making them very promising for a variety of important applications, especially in the adsorption and separation of small gases and hydrocarbons. Numerous studies have demonstrated that MOFs with multifunctional groups, such as open metal sites (OMSs) and Lewis basic sites (LBSs), interact strongly with carbon dioxide and are particularly effective in its capture and separation from binary mixtures of CO(2) and N(2). In this feature article, we briefly review the current state of MOF development in this area, with an emphasis on the effect of multifunctional groups on the selectivity and capacity of MOFs for the CO(2) capture from flue gas mixtures.

  7. Mesoporous silica functionalized with 1-furoyl thiourea urea for Hg(II) adsorption from aqueous media.

    PubMed

    Mureseanu, Mihaela; Reiss, Aurora; Cioatera, Nicoleta; Trandafir, Ion; Hulea, Vasile

    2010-10-15

    New organic-inorganic hybrid materials were prepared by covalently anchoring 1-furoyl thiourea on mesoporous silica (SBA-15). By means of various characterization techniques (X-ray diffraction, nitrogen adsorption-desorption, thermogravimetric analysis, and FTIR spectroscopy) it has been established that the organic groups were successfully anchored on the SBA-15 surfaces and the ordering of the inorganic support was preserved during the chemical modifications. The hybrid sorbents exhibited good ability to remove Hg(II) from aqueous solution. Thus, at pH 6, the adsorption capacity of mercury ions reached 0.61 mmol g(-1).

  8. Tuning ethylene gas adsorption via metal node modulation: Cu-MOF-74 for a high ethylene deliverable capacity.

    PubMed

    Liao, Yijun; Zhang, Lin; Weston, Mitchell H; Morris, William; Hupp, Joseph T; Farha, Omar K

    2017-08-17

    M-MOF-74s were examined for potential applications in ethylene abatement and/or storage/delivery. Due to labile binding resulting from a Jahn-Teller distortion, Cu-MOF-74 exhibits a gradual initial uptake that, in turn, translates into the highest deliverable capacity among the MOFs examined (3.6 mmol g(-1)). In contrast, Co-MOF-74 is the most promising candidate for ethylene abatement due to the sharp uptake at low pressure.

  9. Long-Life and High-Areal-Capacity Li-S Batteries Enabled by a Light-Weight Polar Host with Intrinsic Polysulfide Adsorption.

    PubMed

    Pang, Quan; Nazar, Linda F

    2016-04-26

    Lithium-sulfur batteries are attractive electrochemical energy storage systems due to their high theoretical energy density and very high natural abundance of sulfur. However, practically, Li-S batteries suffer from short cycling life and low sulfur utilization, particularly in the case of high-sulfur-loaded cathodes. Here, we report on a light-weight nanoporous graphitic carbon nitride (high-surface-area g-C3N4) that enables a sulfur electrode with an ultralow long-term capacity fade rate of 0.04% per cycle over 1500 cycles at a practical C/2 rate. More importantly, it exhibits good high-sulfur-loading areal capacity (up to 3.5 mAh cm(-2)) with stable cell performance. We demonstrate the strong chemical interaction of g-C3N4 with polysulfides using a combination of spectroscopic experimental studies and first-principles calculations. The 53.5% concentration of accessible pyridinic nitrogen polysulfide adsorption sites is shown to be key for the greatly improved cycling performance compared to that of N-doped carbons.

  10. Immobilization of mercury by carboxymethyl cellulose stabilized iron sulfide nanoparticles: reaction mechanisms and effects of stabilizer and water chemistry.

    PubMed

    Gong, Yanyan; Liu, Yuanyuan; Xiong, Zhong; Zhao, Dongye

    2014-04-01

    Iron sulfide (FeS) nanoparticles were prepared with sodium carboxymethyl cellulose (CMC) as a stabilizer, and tested for enhanced removal of aqueous mercury (Hg(2+)). CMC at ≥0.03 wt % fully stabilized 0.5 g/L of FeS (i.e., CMC-to-FeS molar ratio ≥0.0006). FTIR spectra suggested that CMC molecules were attached to the nanoparticles through bidentate bridging and hydrogen bonding. Increasing the CMC-to-FeS molar ratio from 0 to 0.0006 enhanced mercury sorption capacity by 20%; yet, increasing the ratio from 0.0010 to 0.0025 diminished the sorption by 14%. FTIR and XRD analyses suggested that precipitation (formation of cinnabar and metacinnabar), ion exchange (formation of Hg0.89Fe0.11S), and surface complexation were important mechanisms for mercury removal. A pseudo-second-order kinetic model was able to interpret the sorption kinetics, whereas a dual-mode isotherm model was proposed to simulate the isotherms, which considers precipitation and adsorption. High mercury uptake was observed over the pH range of 6.5-10.5, whereas significant capacity loss was observed at pH < 6. High concentrations of Cl(-) (>106 mg/L) and organic matter (5 mg/L as TOC) modestly inhibited mercury uptake. The immobilized mercury remained stable when preserved for 2.5 years at pH above neutral.

  11. Single-Walled Carbon Nanotubes (SWCNTs), as a Novel Sorbent for Determination of Mercury in Air

    PubMed Central

    Golbabaei, Farideh; Ebrahimi, Ali; Shirkhanloo, Hamid; Koohpaei, Alireza; Faghihi-Zarandi, Ali

    2016-01-01

    Background: Based on the noticeable toxicity and numerous application of mercury in industries, removal of mercury vapor through sorbent is an important environmental challenge. Purpose of the Study: Due to their highly porous and hollow structure, large specific surface area, light mass density and strong interaction, Single-Walled Carbon Nanotubes (SWCNTs) sorbent were selected for this investigation. Methods: In this study, instrumental conditions, method procedure and different effective parameters such as adsorption efficiency, desorption capacity, time, temperature and repeatability as well as retention time of adsorbed mercury were studied and optimized. Also, mercury vapor was determined by cold vapor atomic absorption spectrometry (CV-AAS). Obtained data were analyzed by Independent T- test, Multivariate linear regression and one way–ANOVA finally. Results: For 80 mg nanotubes, working range of SWCNT were achieved 0.02-0.7 μg with linear range (R2=0.994). Our data revealed that maximum absorption capacity was 0.5 μg g-1 as well as limit of detection (LOD) for studied sorbent was 0.006 μg. Also, optimum time and temperature were reported, 10 min and 250 °C respectively. Retention time of mercury on CNTs for three weeks was over 90%. Results of repeated trials indicated that the CNTs had long life, so that after 30 cycles of experiments, efficiency was determined without performance loss. Conclusion: Results showed that carbon nanotubes have high potential for efficient extraction of mercury from air and can be used for occupational and environmental purposes. The study of adsorption properties of CNTs is recommended. PMID:26925918

  12. Control of mercury pollution.

    PubMed

    Noyes, O R; Hamdy, M K; Muse, L A

    1976-01-01

    When a 203Ng(NO3)2 solution was kept at 25 degrees C in glass or polypropylene containers, 50 and 80% of original radioactivity was adsorbed to the containers' walls after 1 and 4 days, respectively. However, no loss in radioactivity was observed if the solution was supplemented with HgCl as carrier (100 mug Hg2+/ml) and stored in either container for 13 days. When 203Hg2+ was dissolved in glucose basal salt broth with added carrier, levels of 203Hg2+ in solution (kept in glass) decreased to 80 and 70% of original after 1 and 5 days and decreased even more if stored in polypropylene (60 and 40% of original activity after 1 and 4 days, respectively). In the absence of carrier, decreases of 203Hg2+ activities in media stored in either container were more pronounced due to chemisorption (but) not diffusion. The following factors affecting the removal of mercurials from aqueous solution stored in glass were examined: type and concentration of adsorbent (fiber glass and rubber powder); pH; pretreatment of the rubber; and the form of mercury used. Rubber was equally effective in the adsorption of organic and inorganic mercury. The pH of the aqueous 203Hg2+ solution was not a critical factor in the rate of adsorption of mercury by the rubber. In addition, the effect of soaking the rubber in water for 18 hr did not show any statistical difference when compared with nontreated rubber. It can be concluded that rubber is a very effective adsorbent of mercury and, thus, can be used as a simple method for control of mercury pollution.

  13. Mercury and Your Health

    MedlinePlus

    ... the Risk of Exposure to Mercury Learn About Mercury What is Mercury What is Metallic mercury? Toxicological Profile ToxFAQs Mercury Resources CDC’s National Biomonitoring Program Factsheet on Mercury ...

  14. Volatilization of Mercury By Bacteria

    PubMed Central

    Magos, L.; Tuffery, A. A.; Clarkson, T. W.

    1964-01-01

    Volatilization of mercury has been observed from various biological media (tissue homogenates, infusion broth, plasma, urine) containing mercuric chloride. That micro-organisms were responsible was indicated by the finding that the rates of volatilization were highly variable, that a latent period often preceded volatilization, that toluene inhibited the process, and that the capacity to volatilize mercury could be transferred from one biological medium to another. Two species of bacteria when isolated and cultured from these homogenates were able to volatilize mercury. Two other bacteria, one of which was isolated from the local water supply, were also highly active. The volatile mercury was identified as mercury vapour. The importance of these findings in relation to the storage of urine samples prior to mercury analysis is discussed. PMID:14249899

  15. Stoichiometry and kinetics of mercury uptake by photosynthetic bacteria.

    PubMed

    Kis, Mariann; Sipka, Gábor; Maróti, Péter

    2017-05-01

    Mercury adsorption on the cell surface and intracellular uptake by bacteria represent the key first step in the production and accumulation of highly toxic mercury in living organisms. In this work, the biophysical characteristics of mercury bioaccumulation are studied in intact cells of photosynthetic bacteria by use of analytical (dithizone) assay and physiological photosynthetic markers (pigment content, fluorescence induction, and membrane potential) to determine the amount of mercury ions bound to the cell surface and taken up by the cell. It is shown that the Hg(II) uptake mechanism (1) has two kinetically distinguishable components, (2) includes co-opted influx through heavy metal transporters since the slow component is inhibited by Ca(2+) channel blockers, (3) shows complex pH dependence demonstrating the competition of ligand binding of Hg(II) ions with H(+) ions (low pH) and high tendency of complex formation of Hg(II) with hydroxyl ions (high pH), and (4) is not a passive but an energy-dependent process as evidenced by light activation and inhibition by protonophore. Photosynthetic bacteria can accumulate Hg(II) in amounts much (about 10(5)) greater than their own masses by well-defined strong and weak binding sites with equilibrium binding constants in the range of 1 (μM)(-1) and 1 (mM)(-1), respectively. The strong binding sites are attributed to sulfhydryl groups as the uptake is blocked by use of sulfhydryl modifying agents and their number is much (two orders of magnitude) smaller than the number of weak binding sites. Biofilms developed by some bacteria (e.g., Rvx. gelatinosus) increase the mercury binding capacity further by a factor of about five. Photosynthetic bacteria in the light act as a sponge of Hg(II) and can be potentially used for biomonitoring and bioremediation of mercury-contaminated aqueous cultures.

  16. [Mercury poisoning].

    PubMed

    Bensefa-Colas, L; Andujar, P; Descatha, A

    2011-07-01

    Mercury is a widespread heavy metal with potential severe impacts on human health. Exposure conditions to mercury and profile of toxicity among humans depend on the chemical forms of the mercury: elemental or metallic mercury, inorganic or organic mercury compounds. This article aims to reviewing and synthesizing the main knowledge of the mercury toxicity and its organic compounds that clinicians should know. Acute inhalation of metallic or inorganic mercury vapours mainly induces pulmonary diseases, whereas chronic inhalation rather induces neurological or renal disorders (encephalopathy and interstitial or glomerular nephritis). Methylmercury poisonings from intoxicated food occurred among some populations resulting in neurological disorders and developmental troubles for children exposed in utero. Treatment using chelating agents is recommended in case of symptomatic acute mercury intoxication; sometimes it improves the clinical effects of chronic mercury poisoning. Although it is currently rare to encounter situations of severe intoxication, efforts remain necessary to decrease the mercury concentration in the environment and to reduce risk on human health due to low level exposure (dental amalgam, fish contamination by organic mercury compounds…). In case of occupational exposure to mercury and its compounds, some disorders could be compensated in France. Clinicians should work with toxicologists for the diagnosis and treatment of mercury intoxication.

  17. A first-principles study of Hg adsorption on Pd(1 1 1) and Pd/γ-Al2O3(1 1 0) surfaces

    NASA Astrophysics Data System (ADS)

    Geng, Lu; Han, Lina; Cen, Wanglai; Wang, Jiancheng; Chang, Liping; Kong, Dejin; Feng, Gang

    2014-12-01

    Spin-polarized density functional theory calculations were carried out to investigate the adsorption of Hgn (n = 1-3) on the perfect, step and vacancy-defective Pd(1 1 1) surfaces as well as the Pd/γ-Al2O3(1 1 0) surface. It is found that Hg atoms prefer to adsorb on the hollow sites on Pd(1 1 1) surfaces. The adsorption of Hg on the step and vacancy-defective Pd(1 1 1) surfaces is stronger than on the perfect Pd(1 1 1) surface, which indicates that the existence of vacancy and step defects can enhance the mercury adsorption activity of Pd adsorbents. As indicated by the calculated adsorption energies, the mercury adsorption on γ-Al2O3 is weak. The γ-Al2O3 supported single Pd atom shows as good Hg adsorption activity as the perfect Pd(1 1 1) surface at low Hg coverage, while more coordination unsaturated active Pd atoms is needed to achieve high Hg adsorption capacity. In addition, it was also found that the Hg adsorption on Pd/γ-Al2O3 weakens the binding of Pd to the γ-Al2O3 surface.

  18. Reduction of mercury, copper, nickel, cadmium, and zinc levels in solution by competitive adsorption onto peanut hulls, and raw and aged bark.

    PubMed

    Henderson, R W; Andrews, D S; Lightsey, G R; Poonawala, N A

    1977-03-01

    The competitive adsorption of common heavy metal ions by peanut hulls, raw bark, and composted bark was studied. These solid wastes were found to adsorb significant amounts of one or more of the heavy metals (Hg, Cu, Ni, Cd, Zn) commonly found in municipal sludge and wastewater.

  19. Planet Mercury

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Mariner 10's first image of Mercury acquired on March 24, 1974. During its flight, Mariner 10's trajectory brought it behind the lighted hemisphere of Mercury, where this image was taken, in order to acquire important measurements with other instruments.

    This picture was acquired from a distance of 3,340,000 miles (5,380,000 km) from the surface of Mercury. The diameter of Mercury (3,031 miles; 4,878 km) is about 1/3 that of Earth.

    Images of Mercury were acquired in two steps, an inbound leg (images acquired before passing into Mercury's shadow) and an outbound leg (after exiting from Mercury's shadow). More than 2300 useful images of Mercury were taken, both moderate resolution (3-20 km/pixel) color and high resolution (better than 1 km/pixel) black and white coverage.

  20. Carbon dioxide adsorption in chemically activated carbon from sewage sludge.

    PubMed

    de Andrés, Juan Manuel; Orjales, Luis; Narros, Adolfo; de la Fuente, María del Mar; Encarnación Rodríguez, María

    2013-05-01

    In this work, sewage sludge was used as precursor in the production of activated carbon by means of chemical activation with KOH and NaOH. The sludge-based activated carbons were investigated for their gaseous adsorption characteristics using CO2 as adsorbate. Although both chemicals were effective in the development of the adsorption capacity, the best results were obtained with solid NaOH (SBA(T16)). Adsorption results were modeled according to the Langmuir and Freundlich models, with resulting CO2 adsorption capacities about 56 mg/g. The SBA(T16) was characterized for its surface and pore characteristics using continuous volumetric nitrogen gas adsorption and mercury porosimetry. The results informed about the mesoporous character of the SBA(T16) (average pore diameter of 56.5 angstroms). The Brunauer-Emmett-Teller (BET) surface area of the SBA(T16) was low (179 m2/g) in comparison with a commercial activated carbon (Airpel 10; 1020 m2/g) and was mainly composed of mesopores and macropores. On the other hand, the SBA(T16) adsorption capacity was higher than that of Airpel 10, which can be explained by the formation of basic surface sites in the SBA(T16) where CO2 experienced chemisorption. According to these results, it can be concluded that the use of sewage-sludge-based activated carbons is a promising option for the capture of CO2. Adsorption methods are one of the current ways to reduce CO2 emissions. Taking this into account, sewage-sludge-based activated carbons were produced to study their CO2 adsorption capacity. Specifically, chemical activation with KOH and NaOH of previously pyrolyzed sewage sludge was carried out. The results obtained show that even with a low BET surface area, the adsorption capacity of these materials was comparable to that of a commercial activated carbon. As a consequence, the use of sewage-sludge-based activated carbons is a promising option for the capture of CO2 and an interesting application for this waste.

  1. Adsorption of Ag, Cu and Hg from aqueous solutions using expanded perlite.

    PubMed

    Ghassabzadeh, Hamid; Mohadespour, Ahmad; Torab-Mostaedi, Meisam; Zaheri, Parisa; Maragheh, Mohammad Ghannadi; Taheri, Hossein

    2010-05-15

    The aim of the present work was to investigate the ability of expanded perlite (EP) to remove of silver, copper and mercury ions from aqueous solutions. Batch adsorption experiments were carried out and the effect of pH, adsorbent dosage, contact time and temperature of solution on the removal process has been investigated. The optimum pH for the adsorption was found to be 6.5. Adsorption of these metal ions reached their equilibrium concentration in 120, 240 and 180 min for Ag (I), Cu (II) and Hg (II) ions, respectively. Experimental data were also evaluated in terms of kinetic characteristics of adsorption and it was found that adsorption process for these metal ions followed well pseudo-second-order kinetics. Using Langmuir isotherm model, maximum adsorption capacity of EP was found to be 8.46, 1.95 and 0.35 mg/g for Ag (I), Cu (II) and Hg (II) ions, respectively. Finally, the thermodynamic parameters including, the change of free energy (DeltaG degrees ), enthalpy (DeltaH degrees ) and entropy (DeltaS degrees ) of adsorption were calculated for each metal ion. The results showed that the adsorption of these metal ions on EP was feasible and exothermic at 20-50 degrees C.

  2. CTAB-assisted synthesis of mesoporous F-N-codoped TiO 2 powders with high visible-light-driven catalytic activity and adsorption capacity

    NASA Astrophysics Data System (ADS)

    Xie, Yi; Zhao, Xiujian; Li, Yuanzhi; Zhao, Qingnan; Zhou, Xuedong; Yuan, Qihua

    2008-08-01

    This article describes the preparation of mesoporous rod-like F-N-codoped TiO 2 powder photocatalysts with anatase phase via a sol-gel route at the temperature of 373 K, using cetyltrimethyl ammonium bromide (CTAB) as surfactant. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance spectra (UV-vis DRS). The results showed that the photocatalysts possessed a homogeneous pore diameter and a high surface area of 106.3-160.7 m 3 g -1. The increasing CTAB reactive concentration extended the visible-light absorption up to 600 nm. The F-N-codoped TiO 2 powders exhibited significant higher adsorption capacity for methyl orange (MO) than that of Degussa P25 and showed more than 6 times higher visible-light-induced catalytic degradation for MO than that of P25.

  3. Mercury Project

    NASA Image and Video Library

    1959-04-27

    Astronaut L. Gordon Cooper, Jr., one of the original seven astronauts for Mercury Project selected by NASA on April 27, 1959. The MA-9 mission, boosted by the Mercury-Atlas launch vehicle, was the last flight of the Mercury Project. The Faith 7 spacecraft orbited the Earth 22 times in 1-1/2 days.

  4. Nanostructured Silica-Gel Doped with TiO2 for Mercury Vapor Control

    NASA Astrophysics Data System (ADS)

    Pitoniak, Erik; Wu, Chang-Yu; Londeree, Danielle; Mazyck, David; Bonzongo, Jean-Claude; Powers, Kevin; Sigmund, Wolfgang

    2003-08-01

    A novel high surface area SiO2-TiO2 composite has been developed for elemental mercury vapor removal from combustion sources. The composite exhibits synergistic adsorption and photocatalytic oxidation. Mercury vapor in the gas stream is adsorbed, oxidized and stays on the composite. The composite has demonstrated a high mercury capacity (1512ug/g) although in its current 3-mm pellet form only the outer layer is effectively utilized. The loading of 13% TiO2 shows the best removal, both with and without UV irradiation. Increasing TiO2 loading beyond this level does not enhance the removal further. It has also been observed that the composite after being 'activated' by photocatalytic oxidation has better performance, probably due to the change of surface functional groups. The examination of the effects of flow velocity reveals that mass transfer is the rate limiting step. Relative humidity has been found to impede adsorption therefore decreasing the overall removal efficiency. By rinsing with acid, both the deposited mercury and composite can be regenerated.

  5. Preparation, characterization, and application of modified chitosan sorbents for elemental mercury removal

    SciTech Connect

    Zhang, A.C.; Xiang, J.; Sun, L.S.; Hu, S.; Li, P.S.; Shi, J.M.; Fu, P.; Su, S.

    2009-05-15

    A series of raw, iodine (bromide) or/and sulfuric acid-modified chitosan sorbents were synthesized and comprehensively characterized by N{sub 2} isotherm adsorption/desorption method, TGA, FTIR, XRD, and XPS et al. Adsorption experiments of vapor-phase elemental mercury (Hg{sup 0}) were studied using the sorbents in a laboratory-scale fixed-bed reactor. The results revealed that porosities and specific surface areas of the sorbents decreased after modification. The sorbents operated stably at flue-gas temperature below 140{sup o}C. The chemical reactions of iodine and sulfate ion with the amide of chitosan occurred, and the I{sub 2} was found in the sorbents due to the presence of H{sub 2}SO{sub 4}. Fixed-bed adsorber tests showed that compared to raw chitosan, the bromide or iodine-modified chitosan could promote the efficiency of Hg{sub 0} capture more or less. Mercury removal efficiency could be significantly promoted when an appropriate content of H{sub 2}SO{sub 4} was added, and the iodine and H{sub 2}SO{sub 4} modified sorbents almost had a mercury removal efficiency of 100% for 3 h. The presence of moisture can increase the sorbent's capacity for mercury uptake due to the existence of active sites, such as sulfonate and amino group. The mercury breakthrough of modified chitosan sorbents decreased with increasing temperature. A reaction scheme that could explain the experimental results was presumed based on the characterizations and adsorption study.

  6. 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.

  7. Got Mercury?

    NASA Technical Reports Server (NTRS)

    Meyers, Valerie E.; McCoy, J. Torin; Garcia, Hector D.; James, John T.

    2009-01-01

    Many of the operational and payload lighting units used in various spacecraft contain elemental mercury. If these devices were damaged on-orbit, elemental mercury could be released into the cabin. Although there are plans to replace operational units with alternate light sources, such as LEDs, that do not contain mercury, mercury-containing lamps efficiently produce high quality illumination and may never be completely replaced on orbit. Therefore, exposure to elemental mercury during spaceflight will remain possible and represents a toxicological hazard. Elemental mercury is a liquid metal that vaporizes slowly at room temperature. However, it may be completely vaporized at the elevated operating temperatures of lamps. Although liquid mercury is not readily absorbed through the skin or digestive tract, mercury vapors are efficiently absorbed through the respiratory tract. Therefore, the amount of mercury in the vapor form must be estimated. For mercury releases from lamps that are not being operated, we utilized a study conducted by the New Jersey Department of Environmental Quality to calculate the amount of mercury vapor expected to form over a 2-week period. For longer missions and for mercury releases occurring when lamps are operating, we conservatively assumed complete volatilization of the available mercury. Because current spacecraft environmental control systems are unable to remove mercury vapors, both short-term and long-term exposures to mercury vapors are possible. Acute exposure to high concentrations of mercury vapors can cause irritation of the respiratory tract and behavioral symptoms, such as irritability and hyperactivity. Chronic exposure can result in damage to the nervous system (tremors, memory loss, insomnia, etc.) and kidneys (proteinurea). Therefore, the JSC Toxicology Group recommends that stringent safety controls and verifications (vibrational testing, etc.) be applied to any hardware that contains elemental mercury that could yield

  8. Got Mercury?

    NASA Technical Reports Server (NTRS)

    Meyers, Valerie E.; McCoy, J. Torin; Garcia, Hector D.; James, John T.

    2009-01-01

    Many of the operational and payload lighting units used in various spacecraft contain elemental mercury. If these devices were damaged on-orbit, elemental mercury could be released into the cabin. Although there are plans to replace operational units with alternate light sources, such as LEDs, that do not contain mercury, mercury-containing lamps efficiently produce high quality illumination and may never be completely replaced on orbit. Therefore, exposure to elemental mercury during spaceflight will remain possible and represents a toxicological hazard. Elemental mercury is a liquid metal that vaporizes slowly at room temperature. However, it may be completely vaporized at the elevated operating temperatures of lamps. Although liquid mercury is not readily absorbed through the skin or digestive tract, mercury vapors are efficiently absorbed through the respiratory tract. Therefore, the amount of mercury in the vapor form must be estimated. For mercury releases from lamps that are not being operated, we utilized a study conducted by the New Jersey Department of Environmental Quality to calculate the amount of mercury vapor expected to form over a 2-week period. For longer missions and for mercury releases occurring when lamps are operating, we conservatively assumed complete volatilization of the available mercury. Because current spacecraft environmental control systems are unable to remove mercury vapors, both short-term and long-term exposures to mercury vapors are possible. Acute exposure to high concentrations of mercury vapors can cause irritation of the respiratory tract and behavioral symptoms, such as irritability and hyperactivity. Chronic exposure can result in damage to the nervous system (tremors, memory loss, insomnia, etc.) and kidneys (proteinurea). Therefore, the JSC Toxicology Group recommends that stringent safety controls and verifications (vibrational testing, etc.) be applied to any hardware that contains elemental mercury that could yield

  9. Adsorption of peptide nucleic acid and DNA decamers at electrically charged surfaces.

    PubMed Central

    Fojta, M; Vetterl, V; Tomschik, M; Jelen, F; Nielsen, P; Wang, J; Palecek, E

    1997-01-01

    Adsorption behavior of peptide nucleic acid (PNA) and DNA decamers (GTAGATCACT and the complementary sequence) on a mercury surface was studied by means of AC impedance measurements at a hanging mercury drop electrode. The nucleic acid was first attached to the electrode by adsorption from a 5-microliter drop of PNA (or DNA) solution, and the electrode with the adsorbed nucleic acid layer was then washed and immersed in the blank background electrolyte where the differential capacity C of the electrode double layer was measured as a function of the applied potential E. It was found that the adsorption behavior of the PNA with an electrically neutral backbone differs greatly from that of the DNA (with a negatively charged backbone), whereas the DNA-PNA hybrid shows intermediate behavior. At higher surface coverage PNA molecules associate at the surface, and the minimum value of C is shifted to negative potentials because of intermolecular interactions of PNA at the surface. Prolonged exposure of PNA to highly negative potentials does not result in PNA desorption, whereas almost all of the DNA is removed from the surface at these potentials. Adsorption of PNA decreases with increasing NaCl concentration in the range from 0 to 50 mM NaCl, in contrast to DNA, the adsorption of which increases under the same conditions. PMID:9129832

  10. Adsorption kinetics, thermodynamics and isotherm of Hg(II) from aqueous solutions using buckwheat hulls from Jiaodong of China.

    PubMed

    Wang, Zengdi; Yin, Ping; Qu, Rongjun; Chen, Hou; Wang, Chunhua; Ren, Shuhua

    2013-02-15

    The adsorption kinetics and adsorption isotherms of buckwheat hulls in the region of Jiaodong, China (BHJC) for Hg(II) were investigated. Results revealed that the adsorption kinetics of BHJC for Hg(II) were well described by a pseudo second-order reaction model, and the adsorption thermodynamic parameters ΔG, ΔH and ΔS were -5.83 kJ mol(-1)(35°C), 73.1, and 256 JK(-1) mol(-1), respectively. Moreover, Langmuir, Freundlich and Redlich-Peterson isotherm models were applied to analyse the experimental data and to predict the relevant isotherm parameters. The best interpretation for the experimental data was given by the Langmuir isotherm equation, and the maximum adsorption capacity for Hg(II) is 243.90 mg/g at 35°C. Furthermore, investigation of the adsorption selectivity showed that BHJC displayed strong affinity for mercury in the aqueous solutions and exhibited 100% selectivity for mercury in the presence of Zn(II) and Cd(II).

  11. Enhancement of the adsorption capacity of the light-weight expanded clay aggregate surface for the metronidazole antibiotic by coating with MgO nanoparticles: Studies on the kinetic, isotherm, and effects of environmental parameters.

    PubMed

    Kalhori, Ebrahim Mohammadi; Al-Musawi, Tariq J; Ghahramani, Esmaeil; Kazemian, Hossein; Zarrabi, Mansur

    2017-02-09

    The synthesized MgO nanoparticles were used to coat the light-weight expanded clay aggregates (LECA) and as a metronidazole (MNZ) adsorbent. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier-transformed infrared (FTIR) techniques were employed to study the surface morphology and characteristics of the adsorbents. MgO/LECA clearly revealed the advantages of the nanocomposite particles, showing high specific surface area (76.12 m(2)/g), significant adsorption sites and functional groups. Between pH 5 and 9, the MNZ sorption was not significantly affected. Kinetic studies revealed that the MNZ adsorption closely followed the Avrami model, with no dominant process controlling the sorption rate. The study of the effects of foreign ions revealed that the addition of carbonate raised the MNZ removal efficiency of LECA by 8% and the total removal of MNZ by MgO/LECA. Furthermore, nitrate and hardness only marginally influenced the MNZ removal efficiency and their effects can be ranked in the order of carbonate>nitrate>hardness. The isotherm adsorption of MNZ was best fitted with the Langmuir model enlighten the monolayer MNZ adsorption on the homogeneous LECA and MgO/LECA surfaces. The maximum adsorption capacity under optimum conditions was enhanced from 56.31 to 84.55 mg/g for LECA and MgO/LECA, respectively. These findings demonstrated that the MgO/LECA nanocomposite showed potential as an efficient adsorbent for MNZ removal.

  12. Construction and evaluation of a flow-through cell adapted to a commercial static mercury drop electrode (SMDE) to study the adsorption of Cd(II) and Pb(II) on vermiculite.

    PubMed

    Abate, Gilberto; Lichtig, Jaim; Masini, Jorge C

    2002-09-12

    This paper describes the construction and application of a robust flow-through cell for use with the capillary of a commercial static mercury drop electrode. Linearity of peak current was observed up to 0.50 mumol l(-1) for Cd(II) or Pb(II) in anodic stripping voltammetry experiments performed under continuous flow during the deposition step, using 120 s of deposition time and flow rate of 4.0 ml min(-1). Under these conditions the limits of detection for Cd(II) and Pb(II) were 13 and 17 nmol l(-1), respectively. An analytical throughput of 20 analyses per h was possible using 10 s for cleaning the cell between two samples and including the time needed for the potential scan, which was performed with the flow stopped, using the differential pulse mode for current sampling. The linear dynamic range can be extended up to 5 mumol l(-1) for both cations if the deposition time is decreased to 30 s, a condition in which the sampling throughput is 35 analyses per h. The proposed manifold was used to study the adsorption rates of Cd(II) and Pb(II) onto vermiculite at different pHs, allowing one to perform high sensitivity measurements at high sampling frequency, using low cost instrumentation.

  13. Preconcentration of total mercury from river water by anion exchange mechanism.

    PubMed

    Daye, Mirna; Ouddane, Baghdad; Halwani, Jalal; Hamze, Mariam

    2013-01-01

    A simple and cheap analytical technique was developed for the measurement of total mercury in river water samples using inductively coupled plasma-mass spectrometry (ICP-MS). It is based on the direct complexation of mercury ions using iodide and a cationic surfactant in water for its subsequent solid-phase extraction. Mercury ions are retained on the silica phase as ion pairs in the presence of iodide ions and dodecyltrimethylammonium bromide. Parameters having influential influence on the retention of Hg(II) were investigated: sample flowrate, eluent type, sample volume, iodide and surfactant concentrations. The retained mercury ions are stripped off from silica phase using 10 mL of 8 mol L(-1) HNO3 and quantified by ICP-MS. An enrichment factor of 50 was achieved with a maximum adsorption capacity of 718 μg Hg(II) g(-1). The limit of detection of Hg(II) was 8 pg mL(-1). The developed method was applied for the determination of total mercury in river and tap-water samples.

  14. COMBINED THEORETICAL AND EXPERIMENTAL INVESTIGATION OF MECHANISMS AND KINETICS OF VAPOR-PHASE MERCURY UPTAKE BY CARBONACOUES SURFACES

    SciTech Connect

    Radisav D. Vidic

    2002-05-01

    The first part of this study evaluated the application of a versatile optical technique to study the adsorption and desorption of model adsorbates representative of volatile polar (acetone) and non-polar (propane) organic compounds on a model carbonaceous surface under ultra high vacuum (UHV) conditions. The results showed the strong correlation between optical differential reflectance (ODR) and adsorbate coverage determined by temperature programmed desorption (TPD). ODR technique was proved to be a powerful tool to investigate surface adsorption and desorption from UHV to high pressure conditions. The effects of chemical functionality and surface morphology on the adsorption/desorption behavior of acetone, propane and mercury were investigated for two model carbonaceous surfaces, namely air-cleaved highly oriented pyrolytic graphite (HOPG) and plasma-oxidized HOPG. They can be removed by thermal treatment (> 500 K). The presence of these groups almost completely suppresses propane adsorption at 90K and removal of these groups leads to dramatic increase in adsorption capacity. The amount of acetone adsorbed is independent of surface heat treatment and depends only on total exposure. The effects of morphological heterogeneity is evident for plasma-oxidized HOPG as this substrate provides greater surface area, as well as higher energy binding sites. Mercury adsorption at 100 K on HOPG surfaces with and without chemical functionalities and topological heterogeneity created by plasma oxidation occurs through physisorption. The removal of chemical functionalities from HOPG surface enhances mercury physisorption. Plasma oxidation of HOPG provides additional surface area for mercury adsorption. Mercury adsorption by activated carbon at atmospheric pressure occurs through two distinct mechanisms, physisorption below 348 K and chemisorption above 348 K. No significant impact of oxygen functionalities was observed in the chemisorption region. The key findings of this study

  15. Bone char surface modification by nano-gold coating for elemental mercury vapor removal

    NASA Astrophysics Data System (ADS)

    Assari, Mohamad javad; Rezaee, Abbas; Rangkooy, Hossinali

    2015-07-01

    The present work was done to develop a novel nanocomposite using bone char coated with nano-gold for capture of elemental mercury (Hg0) from air. The morphologies, structures, and chemical constitute of the prepared nanocomposite were evaluated by UV-VIS-NIR, dynamic light-scattering (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, and energy dispersive X-ray spectroscopy (EDS). The capture performance of nanocomposite was evaluated in a needle trap for mercury vapor. An on-line setup based on cold vapor atomic absorption spectrometry (CVAAS) was designed for Hg0 determination. Dynamic capacity of nanocomposite for Hg0 was shown high efficient operating capacity of 586.7 μg/g. As temperature increases, the dynamic adsorption capacity of the nanocomposite was decreased, which are characteristics of physicosorption processes. It was found that the surface modification of bone char with nano-gold has various advantages such as high operating dynamic adsorption capacity and low cost preparation. It was also demonstrated that the developed nanocomposite is suitable for on-line monitoring of Hg0. It could be applied for the laboratory and field studies.

  16. Got Mercury?

    NASA Astrophysics Data System (ADS)

    Meyers, Valerie E.; McCoy, Torin J.; Garcia, Hector D.; James, John T.

    2010-09-01

    Many lamps used in various spacecraft contain elemental mercury, which is efficiently absorbed by the lungs as a vapor. The liquid metal vaporizes slowly at room temperature, but may vaporize completely when lamps are operating. Because current spacecraft environmental control systems are unable to remove mercury vapors, we considered short-term and long-term exposures. We estimated mercury vapor releases from stowed lamps during missions lasting ≤ 30 days, whereas we conservatively assumed complete vaporization from stowed lamps during missions lasting > 30 days and from operating lamps regardless of mission duration. The toxicity of mercury and its lack of removal have led Johnson Space Center’s Toxicology Group to recommend stringent safety controls and verifications for hardware containing elemental mercury that could yield airborne mercury vapor concentrations > 0.1 mg/m3 in the total spacecraft atmosphere for exposures lasting ≤ 30 days, or concentrations > 0.01 mg/m3 for exposures lasting > 30 days.

  17. Mercury Project

    NASA Image and Video Library

    1961-07-21

    Astronaut Virgil Gus Grissom awaits America's second marned space mission, Mercury-Redstone 4 (MR-4) on July 21, 1961. During the 15-minute suborbital flight, the Liberty Bell 7 Mercury spacecraft reached an altitude of 118 miles and traveled 303 miles downrange. It was the fourth flight of the Mercury-Redstone launch vehicle (MR-4), developed by Dr. Wernher von Braun and the rocket team in Huntsville, Alabama.

  18. Mercury Project

    NASA Image and Video Library

    1961-01-01

    Ham, a three-year-old chimpanzee, in the spacesuit he would wear for the second Mercury- Redstone (MR-2) suborbital test flight in January, 1961. NASA used chimpanzees and other primates to test the Mercury capsule before launching the fisrt American astronaut, Alan Shepard, in May 1961. The Mercury capsule rode atop a modified Redstone rocket, developed by Dr. Wernher von Braun and the German Rocket Team in Huntsville, Alabama.

  19. Mercury Project

    NASA Image and Video Library

    1959-01-01

    Dr. Wernher von Braun, Director of the Army Ballistic Missile Agency's (ABMA) Development Operations Division, poses with the original Mercury astronauts in ABMA's Fabrication Laboratory during a 1959 visit. Inspecting Mercury-Redstone hardware are from left to right, Alan Shepard, Donald Deke Slayton, Virgil Gus Grissom, von Braun, Gordon Cooper, Wally Schirra, John Glenn, and Scott Carpenter. Project Mercury officially began October 7, 1958 as the United States' first manned space program.

  20. Potential anthropogenic mobilisation of mercury and arsenic from soils on mineralised rocks, Northland, New Zealand.

    PubMed

    Craw, D

    2005-02-01

    Eroded roots of hot spring systems in Northland, New Zealand consist of mineralised rocks containing sulfide minerals. Marcasite and cinnabar are the dominant sulfides with subordinate pyrite. Deep weathering and leached soil formation has occurred in a warm temperate to subtropical climate with up to 3 m/year rainfall. Decomposition of the iron sulfides in natural and anthropogenic rock exposures yields acid rock drainage with pH typically between 2 and 4, and locally down to pH 1. Soils and weathered rocks developed on basement greywacke have negligible acid neutralisation capacity. Natural rainforest soils have pH between 4 and 5 on unmineralised greywacke, and pH is as low as 3.5 in soils on mineralised rocks. Roads with aggregate made from mineralised rocks have pH near 3, and quarries from which the rock was extracted can have pH down to 1. Mineralised rocks are enriched in arsenic and mercury, both of which are environmentally available as solid solution impurities in iron sulfides and phosphate minerals. Base metals (Cu, Pb, Zn) are present at low levels in soils, at or below typical basement rock background. Decomposition of the iron sulfides releases the solid solution arsenic and mercury into the acid rock drainage solutions. Phosphate minerals release their impurities only under strongly acid conditions (pH<1). Arsenic and mercury are adsorbed on to iron oxyhydroxides in soils, concentrated in the C horizon, with up to 4000 ppm arsenic and 100 ppm mercury. Waters emanating from acid rock drainage areas have arsenic and mercury below drinking water limits. Leaching experiments and theoretical predictions indicate that both arsenic and mercury are least mobile in acid soils, at pH of c. 3-4. This optimum pH range for fixation of arsenic and mercury on iron oxyhydroxides in soils is similar to natural pH at the field site of this study. However, neutralisation of acid soils developed on mineralised rocks is likely to decrease adsorption and enhance

  1. Development of Nano-Sulfide Sorbent for Efficient Removal of Elemental Mercury from Coal Combustion Fuel Gas.

    PubMed

    Li, Hailong; Zhu, Lei; Wang, Jun; Li, Liqing; Shih, Kaimin

    2016-09-06

    The surface area of zinc sulfide (ZnS) was successfully enlarged using nanostructure particles synthesized by a liquid-phase precipitation method. The ZnS with the highest surface area (named Nano-ZnS) of 196.1 m(2)·g(-1) was then used to remove gas-phase elemental mercury (Hg(0)) from simulated coal combustion fuel gas at relatively high temperatures (140 to 260 °C). The Nano-ZnS exhibited far greater Hg(0) adsorption capacity than the conventional bulk ZnS sorbent due to the abundance of surface sulfur sites, which have a high binding affinity for Hg(0). Hg(0) was first physically adsorbed on the sorbent surface and then reacted with the adjacent surface sulfur to form the most stable mercury compound, HgS, which was confirmed by X-ray photoelectron spectroscopy analysis and a temperature-programmed desorption test. At the optimal temperature of 180 °C, the equilibrium Hg(0) adsorption capacity of the Nano-ZnS (inlet Hg(0) concentration of 65.0 μg·m(-3)) was greater than 497.84 μg·g(-1). Compared with several commercial activated carbons used exclusively for gas-phase mercury removal, the Nano-ZnS was superior in both Hg(0) adsorption capacity and adsorption rate. With this excellent Hg(0) removal performance, noncarbon Nano-ZnS may prove to be an advantageous alternative to activated carbon for Hg(0) removal in power plants equipped with particulate matter control devices, while also offering a means of reusing fly ash as a valuable resource, for example as a concrete additive.

  2. Efficient removal of mercury from aqueous solutions and industrial effluent.

    PubMed

    Dos Santos, Maria B P; Leal, Katia Z; Oliveira, Fernando J S; Sella, Silvia M; Vieira, Méri D; Marques, Elisa M D; Gomes, Vanessa A C

    2015-01-01

    The objective of this study was to examine the ability of a solid waste produced during beneficiation of ornamental rocks to remove mercury (Hg) from an industrial effluent and aqueous solutions under various conditions. Batch studies have been carried out by observing the effects of pH, concentration of the adsorbate, contact time, and so on. Various sorption isotherm models such as Langmuir, Freundlich, and Tóth have been applied for the adsorbent. Film and intraparticle diffusion were both found to be rate-limiting steps. Adsorption was properly described by the Freundlich model (capacity constant of 0.3090 (mg g(-1))(mg L(-1))(-1/n) and adsorption intensity indicator of 2.2939), which indicated a favorable sorption and encouraged subsequent studies for treatment of Hg-containing industrial effluent. Industrial effluent treatment efficiency reached Hg removals greater than 90% by using ornamental rock solid waste (ORSW). Besides, desorption studies indicated that the maximum recovery of mercury was 100 ± 2% for 1 mol L(-1) HNO3 and 74 ± 8% for 0.1 mol L(-1) HNO3. The ORSW could be reused thrice without significant difference on the Hg removal rate from industrial effluent. These findings place ORSW as a promising efficient and low-cost adsorbent for the removal of Hg from aqueous solutions and industrial effluent.

  3. Electronic storage capacity of ceria: role of peroxide in Aux supported on CeO2(111) facet and CO adsorption.

    PubMed

    Liu, Yinli; Li, Huiying; Yu, Jun; Mao, Dongsen; Lu, Guanzhong

    2015-11-07

    Density functional theory (DFT+U) was used to study the adsorption of Aux (x = 1-4) clusters on the defective CeO2(111) facet and CO adsorption on the corresponding Aux/CeO2-x catalyst, in this work Aux clusters are adsorbed onto the CeO2-x + superoxide/peroxide surface. When Au1 is supported on the CeO2(111) facet with an O vacancy, the strong electronegative Au(δ-) formed is not favorable for CO adsorption. When peroxide is adsorbed on the CeO2(111) facet with the O vacancy, Aux was oxidized, resulting in stable Aux adsorption on the defective ceria surface with peroxide, which promotes CO adsorption on the Aux/CeO2-x catalyst. With more Au atoms in supported Aux clusters, CO adsorption on this surface becomes stronger. During both the Au being supported on CeO2-x and CO being adsorbed on Aux/CeO2-x, CeO2 acts as an electron buffer that can store/release the electrons. These results provide a scientific understanding for the development of high-performance rare earth catalytic materials.

  4. Insights into the adsorption capacity and breakthrough properties of a synthetic zeolite against a mixture of various sulfur species at low ppb levels.

    PubMed

    Vellingiri, Kowsalya; Kim, Ki-Hyun; Kwon, Eilhann E; Deep, Akash; Jo, Sang-Hee; Szulejko, Jan E

    2016-01-15

    The sorptive removal properties of a synthetic A4 zeolite were evaluated against sulfur dioxide (SO2) and four reference reduced sulfur compounds (RSC: hydrogen sulfide (H2S), methanethiol (CH3SH), dimethyl sulfide (DMS, (CH3)2S), and dimethyl disulfide (DMDS, CH3SSCH3). To this end, a sorbent bed of untreated (as-received) A4 zeolite was loaded with gaseous standards at four concentration levels (10-100 part-per-billion (ppb (v/v)) at four different volumes (0.1, 0.2, 0.5, and 1 L increments) in both increasing (IO: 0.1-1.0 L) and decreasing volume order (DO: 1.0 to 0.1 L). Morphological properties were characterized by PXRD, FTIR, and BET analysis. The removal efficiency of SO2 decreased from 100% for all concentrations at 0.1 L (initial sample volume) to ∼82% (100 ppb) or ∼96% (10 ppb) at 3.6 L. In contrast, removal efficiency of RSC was near 100% at small loading volumes but then fell sharply, irrespective of concentration (10-100 ppb) (e.g., 32% (DMS) to 52% (H2S) at 100 ppb). The adsorption capacity of zeolite, if expressed in terms of solid-gas partition coefficient (e.g., similar to the Henry's law constant (mmol kg(-1) Pa(-1))), showed moderate variabilities with the standard concentration levels and S compound types such as the minimum of 2.03 for CH3SH (at 20 ppb) to the maximum of 13.9 for SO2 (at 10 ppb). It clearly demonstrated a notable distinction in the removal efficiency of A4 zeolite among the different S species in a mixture with enhanced removal efficiency of SO2 compared to the RSCs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Mercury Project

    NASA Image and Video Library

    1959-01-01

    In this 1959 photograph, technicians prepare tail sections for Mercury-Redstone vehicles in Building 4706 at Redstone Arsenal in Huntsville, Alabama. Developed by Dr. Wernher von Braun and the rocket team at Redstone, the Mercury-Redstone launched the first two marned U.S. missions.

  6. Mercury Project

    NASA Image and Video Library

    1963-05-16

    The recovery operation of the Faith 7 spacecraft after the completion of the 1-1/2 day orbital flight (MA-9 mission) with Astronaut Gordon Cooper. Navy frogmen attach the flotation collar to the spacecraft. The MA-9 mission was the last flight of the Mercury Project and launched on May 15, 1963 boosted by The Mercury-Atlas launch vehicle.

  7. Mercury Project

    NASA Image and Video Library

    1963-09-09

    Astronaut Alan B. Shepard, one of the original seven astronauts for Mercury Project selected by NASA on April 27, 1959. The Freedom 7 spacecraft boosted by Mercury-Redstone vehicle for the MR-3 mission made the first marned suborbital flight and Astronaut Shepard became the first American in space.

  8. Mercury Project

    NASA Image and Video Library

    1959-04-27

    Astronaut Walter M. "Wally" Schirra, one of the original seven astronauts for Mercury Project selected by NASA on April 27, 1959. The MA-8 (Mercury-Atlas) mission with Sigma 7 spacecraft was the third marned orbital flight by the United States, and made the six orbits in 9-1/4 hours.

  9. Mercury Project

    NASA Image and Video Library

    1959-04-27

    Astronaut Virgil I. "Gus" Grissom, one of the original seven astronauts for Mercury Project selected by NASA on April 27, 1959. The MR-4 mission, boosted by the Mercury-Redstone vehicle, made the second marned suborbital flight. The capsule, Liberty Bell 7, sank into the sea after the splashdown.

  10. Mercury Project

    NASA Image and Video Library

    1959-04-27

    Astronaut John H. Glenn, one of the original seven astronauts for Mercury Project selected by NASA on April 27, 1959. The MA-6 mission, boosted by the Mercury-Atlas vehicle, was the first manned orbital launch by the United States, and carried Astronaut Glenn aboard the Friendship 7 spacecraft to orbit the Earth.

  11. Mercury emissions from municipal solid waste combustors

    SciTech Connect

    Not Available

    1993-05-01

    This report examines emissions of mercury (Hg) from municipal solid waste (MSW) combustion in the United States (US). It is projected that total annual nationwide MSW combustor emissions of mercury could decrease from about 97 tonnes (1989 baseline uncontrolled emissions) to less than about 4 tonnes in the year 2000. This represents approximately a 95 percent reduction in the amount of mercury emitted from combusted MSW compared to the 1989 mercury emissions baseline. The likelihood that routinely achievable mercury emissions removal efficiencies of about 80 percent or more can be assured; it is estimated that MSW combustors in the US could prove to be a comparatively minor source of mercury emissions after about 1995. This forecast assumes that diligent measures to control mercury emissions, such as via use of supplemental control technologies (e.g., carbon adsorption), are generally employed at that time. However, no present consensus was found that such emissions control measures can be implemented industry-wide in the US within this time frame. Although the availability of technology is apparently not a limiting factor, practical implementation of necessary control technology may be limited by administrative constraints and other considerations (e.g., planning, budgeting, regulatory compliance requirements, etc.). These projections assume that: (a) about 80 percent mercury emissions reduction control efficiency is achieved with air pollution control equipment likely to be employed by that time; (b) most cylinder-shaped mercury-zinc (CSMZ) batteries used in hospital applications can be prevented from being disposed into the MSW stream or are replaced with alternative batteries that do not contain mercury; and (c) either the amount of mercury used in fluorescent lamps is decreased to an industry-wide average of about 27 milligrams of mercury per lamp or extensive diversion from the MSW stream of fluorescent lamps that contain mercury is accomplished.

  12. Disposable mercury-free cell-on-a-chip devices with integrated microfabricated electrodes for the determination of trace nickel(II) by adsorptive stripping voltammetry.

    PubMed

    Kokkinos, Christos; Economou, Anastasios; Raptis, Ioannis; Speliotis, Thanassis

    2008-08-01

    This work reports the fabrication of disposable three-electrode cells with integrated sputtered metal-film electrodes. The working electrode was a bismuth-film electrode (BiFE) while the reference and counter electrodes were made of Ag and Pt, respectively. The deposition of the metal layers was carried out by sputtering of the respective metals on a silicon substrate while the exact geometry of the electrodes was defined via a metal mask placed on the substrate during the deposition process. Initially, the electrodes were characterised by cyclic voltammetry. The utility of these devices was tested for the trace determination of Ni(II) by square wave adsorptive stripping voltammetry (SWAdSV) after complexation with dimethylglyoxime (DMG). The experimental variables (the presence of oxygen, the DMG concentration, the preconcentration potential, the accumulation time and the SW parameters), as well as potential interferences, were investigated. Using the selected conditions, the 3sigma limit of detection was 100 ng L(-1) for Ni(II) (for 90 s of preconcentration) and the relative standard deviation for Ni(II) was 2.3% at the 10 microg L(-1) level (n=8). Finally, the method was applied to the determination of Ni(II) in a certified river water sample.

  13. Mercury capture in bench-scale absorbers

    SciTech Connect

    Livengood, C.D.; Huang, H.S.; Mendelsohn, M.H.; Wu, J.M.

    1994-08-01

    This paper gives,a brief overview of research being conducted at Argonne National Laboratory on the capture of mercury by both dry sorbents and wet scrubbers. The emphasis in the research is on development of a better understanding of the key factors that control the capture of mercury. Future work is expected to utilize that information for the development of new or modified process concepts featuring enhanced mercury capture capabilities. The results and conclusions to date from the Argonne -research on dry sorbents can be summarized as follows: lime hydrates, either regular or high-surface-area, are `not effective in removing mercury; mercury removals are enhanced by the addition of activated carbon; mercury removals with activated carbon decrease with increasing temperature, larger particle size, and decreasing mercury concentration in the gas; and chemical pretreatment (e.g., with sulfur or (CaCl{sub 2}) can greatly increase the removal capacity of activated carbon. Preliminary results from the wet scrubbing research include: no removal of elemental mercury is obtained under normal scrubber operating conditions; mercury removal is improved by the addition of packing or production of smaller gas bubbles to increase the gas-liquid contact area; polysulfide solutions do not appear promising for enhancing mercury removal in typical FGC systems; stainless steel packing appears to have beneficial properties for mercury removal and should be investigated further; and other chemical additives may offer greatly enhanced removals.

  14. ELEMENTAL MERCURY CAPTURE BY ACTIVATED CARBON IN A FLOW REACTOR

    EPA Science Inventory


    The paper gives results of bench-scale experiments in a flow reactor to simulate the entrained-flow capture of elemental mercury (Hgo) using solid sorbents. Adsorption of Hgo by a lignite-based activated carbon (Calgon FGD) was examined at different carbon/mercury (C/Hg) rat...

  15. ELEMENTAL MERCURY CAPTURE BY ACTIVATED CARBON IN A FLOW REACTOR

    EPA Science Inventory


    The paper gives results of bench-scale experiments in a flow reactor to simulate the entrained-flow capture of elemental mercury (Hgo) using solid sorbents. Adsorption of Hgo by a lignite-based activated carbon (Calgon FGD) was examined at different carbon/mercury (C/Hg) rat...

  16. Biochar from malt spent rootlets for the removal of mercury from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Boutsika, Lamprini; Manariotis, Ioannis; Karapanagioti, Hrissi K.

    2013-04-01

    Biochar is receiving increased attention as a promising material in environmental applications. It is obtained from the incomplete combustion of carbon-rich biomass under oxygen-limited conditions. One of the many proposed applications of biochars is the removal of metals (e.g., lead, mercury, etc.) from aqueous solutions. Mercury is one of the heavy metals of particular concern due to its toxicity even at relatively low concentration and thus, its removal from aqueous systems is desirable. Malt spent rootlets is a by-product formed during beer production, it is inexpensive and it is produced in high quantities. The objective of the present study was to evaluate the potential use of biochar, produced from malt spent rootlets, to remove mercury from aqueous solutions. Batch experiments were conducted at room temperature (25oC) to obtain the optimum sorption conditions under different pH values, biomass dose, contact time, and solution ionic strength. Sorption kinetics and equilibrium capacity constants were determined at the optimum pH value. Furthermore, the effect of different leaching solutions on mercury desorption from the biochar was examined. All studies with mercury and biochar were conducted at pH 5 that was determined to be the optimum pH for sorption. The proportion of mercury removal increased with the increased dose of the biochar, i.e. from 71% removal for biochar dose of 0.3 g/L, it reached almost 100% removal for biochar dose ˜1 g/L. Based on the isotherm data, the maximum biochar sorption capacity (qmax) for mercury was 99 mg/g. Based on the sorption kinetic data, (qmax) was achieved after 2 h; it should be mentioned that 30% of the (qmax) was observed within the first 5 min. Five leaching solutions were tested for mercury desorption (H2O, HCl, EDTA, NaCl and HNO3). HCl resulted in the highest extraction percentage of the sorbed mercury. The desorbing mercury percentages at 24 h for HCl concentrations 0.1, 0.2, 0.4, 0.8, and 2 M were 62, 59, 62, 69

  17. Micromechanism of sulfurizing activated carbon and its ability to adsorb mercury

    NASA Astrophysics Data System (ADS)

    Wu, Guofang; Xu, Minren; Liu, Qingcai; Yang, Jian; Ma, Dongran; Lu, Cunfang; Lan, Yuanpei

    2013-11-01

    To eliminate mercury from coal-fired flue gas, sulfurization of carbons has been found to be the most inexpensive approach to solve the problem of environment contamination by mercury. This study focuses on improving the adsorption capacity of activate carbon loaded with elemental sulfur as an active phase and further use in the removal of mercury vapors from fuel gas. In this paper, equipment such as the scanning electron microscope, specific surface area test machine and fluorescence spectrophotometer are employed to study the ability of the S-loaded activated carbon. The results show that unmodified activate carbon has smooth hole surface and uneven distributed hole size. Pore walls of activate carbon modified became rougher and the hole size distribution is asymmetrical. Sulfur is uniformly distributed and is mainly bonded on the surface of the skeleton of activate carbon. In addition, a small amount of granular sulfur was loaded on the surface of the pore walls. Higher temperature creates smaller pore size and larger microporous volume. Improving the process temperature is conducive to the development of micropore and the distribution of sulfur, and a larger amount of small molecular weight sulfur are created, which is helpful in the removal of HgO through chemical adsorption. The optimum modification temperature and holding time is 550 °C and 60 min, which creates the adsorbents of the max absorption capability of 1227.5 μg Hg/g.

  18. Water adsorption at high temperature on core samples from The Geysers geothermal field

    SciTech Connect

    Gruszkiewicz, M.S.; Horita, J.; Simonson, J.M.; Mesmer, R.E.

    1998-06-01

    The quantity of water retained by rock samples taken from three wells located in The Geysers geothermal reservoir, California, was measured at 150, 200, and 250 C as a function of pressure in the range 0.00 {le} p/p{sub 0} {le} 0.98, where p{sub 0} is the saturated water vapor pressure. Both adsorption (increasing pressure) and desorption (decreasing pressure) runs were made in order to investigate the nature and the extent of the hysteresis. Additionally, low temperature gas adsorption analyses were performed on the same rock samples. Nitrogen or krypton adsorption and desorption isotherms at 77 K were used to obtain BET specific surface areas, pore volumes and their distributions with respect to pore sizes. Mercury intrusion porosimetry was also used to obtain similar information extending to very large pores (macropores). A qualitative correlation was found between the surface properties obtained from nitrogen adsorption and the mineralogical and petrological characteristics of the solids. However, there is in general no proportionality between BET specific surface areas and the capacity of the rocks for water adsorption at high temperatures. The results indicate that multilayer adsorption rather than capillary condensation is the dominant water storage mechanism at high temperatures.

  19. Mercury Project

    NASA Image and Video Library

    1961-01-31

    A three-year-old chimpanzee, named Ham, in the biopack couch for the MR-2 suborbital test flight. On January 31, 1961, a Mercury-Redstone launch from Cape Canaveral carried the chimpanzee "Ham" over 640 kilometers down range in an arching trajectory that reached a peak of 254 kilometers above the Earth. The mission was successful and Ham performed his lever-pulling task well in response to the flashing light. NASA used chimpanzees and other primates to test the Mercury Capsule before launching the first American astronaut Alan Shepard in May 1961. The successful flight and recovery confirmed the soundness of the Mercury-Redstone systems.

  20. Mercury Project

    NASA Image and Video Library

    1961-01-01

    A three-year-old chimpanzee, named Ham, in the biopack couch for the MR-2 suborbital test flight. On January 31, 1961, a Mercury-Redstone launch from Cape Canaveral carried the chimpanzee "Ham" over 640 kilometers down range in an arching trajectory that reached a peak of 254 kilometers above the Earth. The mission was successful and Ham performed his lever-pulling task well in response to the flashing light. NASA used chimpanzees and other primates to test the Mercury Capsule before launching the first American astronaut Alan Shepard in May 1961. The successful flight and recovery confirmed the soundness of the Mercury-Redstone systems.

  1. Biosorption of mercury by Macrocystis pyrifera and Undaria pinnatifida: influence of zinc, cadmium and nickel.

    PubMed

    Plaza, Josefina; Viera, Marisa; Donati, Edgardo; Guibal, Eric

    2011-01-01

    This study investigated the adsorption of Hg(II) on Macrocystis pyrifera and Undaria pinnatifida in monometallic system in the presence of Zn(II), Cd(II) and Ni(II). The two biosorbents reached the same maximum sorption capacity (q(m) = 0.8 mmol/g) for mercury. U. pinnatifida showed a greater affinity (given by the coefficient b of the Langmuir equation) for mercury compared to M. pyrifera (4.4 versus 2.7 L/mmol). Mercury uptake was significantly reduced (by more than 50%) in the presence of competitor heavy metals such as Zn(II), Cd(II) and Ni(II). Samples analysis using an environmental scanning electron microscopy equipped with an energy dispersive X-ray microanalysis showed that mercury was heterogeneously adsorbed on the surface of both biomaterials, while the other heavy metals were homogeneous distributed. The analysis of biosorbents by Fourier transform infrared spectrometry indicated that Hg(II) binding occurred on S = O (sulfonate) and N-H (amine) functional groups.

  2. Mercury Project

    NASA Image and Video Library

    1961-05-05

    Dr. von Braun addresses a crowd celebrating in front of the Madison County Alabama Courthouse following the successful launch of Astronaut Alan Shepard (America's first astronaut in space) into space on a Mercury-Redstone Launch Vehicle, Freedom 7. Shepard's Mercury Spacecraft, was launched from Cape Canaveral. He reached a speed of 5200 mph. His flight lasted 15-1/2 minutes. May 5, 1961 (Photo: Courtesy of Huntsville/Madison County Public Library)

  3. Mercury Project

    NASA Image and Video Library

    1950-01-01

    A Mercury-Redstone launch vehicle awaits test-firing in the Redstone Test Stand during the late 1950s. Between 1953 and 1960, the rocket team at Redstone Arsenal in Huntsville, Alabama performed hundreds of test firings on the Redstone rocket, over 200 on the Mercury-Redstone vehicle configuration alone. It was this configuration which launched America's first two marned space missions, Freedom 7 and Liberty Bell 7,in 1961.

  4. Mercury Project

    NASA Image and Video Library

    1961-05-05

    Astronaut Alan B. Shepard, Jr. awaits liftoff in the Freedom 7 Mercury spacecraft on May 5, 1961. This third flight of the Mercury-Redstone (MR-3) vehicle, developed by D. Wernher von Braun and the rocket team in Huntsville, Alabama, was the first marned space mission for the United States. During the 15-minute suborbital flight, Shepard reached an altitude of 115 miles and traveled 302 miles downrange.

  5. Mercury Project

    NASA Image and Video Library

    1961-05-05

    Alan B. Shepard, Jr., America's first astronaut, stands in front of the Freedom 7 spacecraft shortly after completion of the third flight of the Mercury-Redstone (MR-3) vehicle, May 5, 1961. During the 15-minute suborbital flight, the Freedom 7 Mercury spacecraft, launched atop a modified Redstone rocket developed by Dr. Wernher von Braun and the rocket team in Huntsville, Alabama, reached an altitude of 115 miles and traveled 302 miles downrange.

  6. 2-Mercaptothiazoline modified mesoporous silica for mercury removal from aqueous media.

    PubMed

    Pérez-Quintanilla, Damián; del Hierro, Isabel; Fajardo, Mariano; Sierra, Isabel

    2006-06-30

    Mesoporous silicas (SBA-15 and MCM-41) have been functionalized by two different methods. Using the heterogeneous route the silylating agent, 3-chloropropyltriethoxysilane, was initially immobilized onto the mesoporous silica surface to give the chlorinated mesoporous silica Cl-SBA-15 or Cl-MCM-41. In a second step a multifunctionalized N, S donor compound (2-mercaptothiazoline, MTZ) was incorporated to obtain the functionalized silicas denoted as MTZ-SBA-15-Het or MTZ-MCM-41-Het. Using the homogeneous route, the functionalization was achieved via the one step reaction of the mesoporous silica with an organic ligand containing the chelating functions, to give the modified mesoporous silicas denoted as MTZ-SBA-15-Hom or MTZ-MCM-41-Hom. The functionalized mesoporous silicas were employed as adsorbents for the regeneration of aqueous solutions contaminated with Hg (II) at room temperature. SBA-15 and MCM-41 functionalized with MTZ by the homogeneous method present good mercury adsorption values (1.10 and 0.7mmolHg (II)/g of silica, respectively). This fact suggests a better applicability of such mesoporous silica supports to extract Hg (II) from aqueous solutions. In addition, it was observed the existence of a correlation between mercury adsorption with pore size and volume since, SBA-15 with lower areas and higher pore sizes functionalized with sterically demanding ligands, show better adsorption capacities than functionalized MCM-41.

  7. Got Mercury?

    NASA Technical Reports Server (NTRS)

    Meyers, Valerie; James, John T.; McCoy, Torin; Garcia, Hector

    2010-01-01

    Many lamps used in various spacecraft contain elemental mercury, which is efficiently absorbed through the lungs as a vapor. The liquid metal vaporizes slowly at room temperature, but may be completely vaporized when lamps are operating. Because current spacecraft environmental control systems are unable to remove mercury vapors, we considered short-term and long-term exposures. Using an existing study, we estimated mercury vapor releases from lamps that are not in operation during missions lasting less than or equal to 30 days; whereas we conservatively assumed complete vaporization from lamps that are operating or being used during missions lasing more than 30 days. Based on mercury toxicity, the Johnson Space Center's Toxicology Group recommends stringent safety controls and verifications for any hardware containing elemental mercury that could yield airborne mercury vapor concentrations greater than 0.1 mg/m3 in the total spacecraft atmosphere for exposures lasting less than or equal to 30 days, or concentrations greater than 0.01 mg/m3 for exposures lasting more than 30 days.

  8. Removal of elemental mercury by iodine-modified rice husk ash sorbents.

    PubMed

    Zhao, Pengfei; Guo, Xin; Zheng, Chuguang

    2010-01-01

    Iodine-modified calcium-based rice husk ash sorbents (I2/CaO/RHA) were synthesized and characterized by X-ray diffraction, X-ray fluorescence, and N2 isotherm adsorption/desorption. Adsorption experiments of vapor-phase elemental mercury (Hg0) were performed in a laboratory-scale fixed-bed reactor. I2/CaO/RHA performances on Hg0 adsorption were compared with those of modified Ca-based fly ash sorbents (I2/CaO/FA) and modified fly ash sorbents (I2/FA). Effects of oxidant loading, supports, pore size distribution, iodine impregnation modes, and temperature were investigated as well to understand the mechanism in capturing Hg0. The modified sorbents exhibited reasonable efficiency for Hg0 removal under simulated flue gas. The surface area, pore size distribution, and iodine impregnation modes of the sorbents did not produce a strong effect on Hg0 capture efficiency, while fair correlation was observed between Hg0 uptake capacity and iodine concentration. Therefore, the content of I2 impregnated on the sorbents was identified as the most important factor influencing the capacity of these sorbents for Hg0 uptake. Increasing temperature in the range of 80-140 degrees C caused a rise in Hg0 removal. A reaction mechanism that may explain the experimental results was presumed based on the characterizations and adsorption study.

  9. Mercury separation from concentrated potassium iodide/iodine leachate using Self-Assembled Mesoporous Mercaptan Support (SAMMS) technology

    SciTech Connect

    Mattigod, S.V.; Feng, X.; Fryxell, G.E.

    1997-10-01

    A study was conducted to demonstrate the effectiveness of a novel adsorber, the Self-Assembled Mesoporous Mercaptan Support (SAMMS) material to remove mercury (Hg) from potassium iodide/iodine (KI/I{sub 2}) waste streams. This study included investigations of the SAMMS material`s binding kinetics, loading capacity, and selectivity for Hg adsorption from surrogate and actual KI/I{sub 2} waste solutions. The kinetics data showed that binding of Hg by the adsorber material occurs very rapidly, with 82% to 95% adsorption occurring within the first 5 min. No significant differences in the rate of adsorption were noted between pH values of 5 and 9 and at Hg concentrations of {approximately}100 mg/1. Within the same range of pH values, an approximate four-fold increase in initial Hg concentration resulted in a two-fold increase in the rate of adsorption. In all cases studied, equilibrium adsorption occured within 4 h. The loading capacity experiments in KI/I{sub 2} surrogate solutions indicated Hg adsorption densities between 26 to 270 mg/g. The loading density increased with increasing solid: solution ratio and decreasing iodide concentrations. Values of distribution coefficients (1.3x10{sup 5} to >2.6x10{sup 8} ml/g) indicated that material adsorbs Hg with very high specificity from KI/I{sub 2} surrogate solutions. Reduction studies showed that compared to metallic iron (Fe), sodium dithionite can very rapidly reduce iodine as the triiodide species into the iodide form. Adsorption studies conducted with actual KI/I{sub 2} leachates confirmed the highly specific Hg adsorption properties (K{sub d}>6x10{sup 7} to>1x10{sup 8} ml//g) of the adsorber material. Following treatment, the Hg concentrations in actual leachates were below instrumental detection limits (i.e., < 0.00005 mg/l), indicating that the KI solutions can be recycled.

  10. Mercury control in 2009

    SciTech Connect

    Sjostrom, S.; Durham, M.; Bustard, J.; Martin, C.

    2009-07-15

    Although activated carbon injection (ACI) has been proven to be effective for many configurations and is a preferred option at many plants sufficient quantities of powdered activated coking (PAC) must be available to meet future needs. The authors estimate that upcoming federal and state regulations will result in tripling the annual US demand for activated carbon to nearly 1.5 billion lb from approximately 450 million lb. Rapid expansion of US production capacity is required. Many PAC manufacturers are discussing expansion of their existing production capabilities. One company, ADA Carbon Solutions, is in the process of constructing the largest activated carbon facility in North America to meet the future demand for PAC as a sorbent for mercury control. Emission control technology development and commercialization is driven by regulation and legislation. Although ACI will not achieve > 90% mercury control at every plant, the expected required MACT legislation level, it offers promise as a low-cost primary mercury control technology option for many configurations and an important trim technology for others. ACI has emerged as the clear mercury-specific control option of choice, representing over 98% of the commercial mercury control system orders to date. As state regulations are implemented and the potential for a federal rule becomes more imminent, suppliers are continuing to develop technologies to improve the cost effectiveness and limit the balance of plant impacts associated with ACI and are developing additional PAC production capabilities to ensure that the industry's needs are met. The commercialisation of ACI is a clear example of industry, through the dedication of many individuals and companies with support from the DOE and EPRI, meeting the challenge of developing cost-effectively reducing emissions from coal-fired power plants. 7 refs., 1 fig.

  11. Removal and recovery of mercury from aqueous solution using magnetic silica nanocomposites

    NASA Astrophysics Data System (ADS)

    Song, Bo Yune; Eom, Yujin; Lee, Tai Gyu

    2011-03-01

    Thiol-functionalized magnetic silica nanocomposite was synthesized and tested for its mercury pick-up capability in aqueous solution. Magnetic property was to be utilized upon the collection of the adsorbents and the recovery adsorbed Hg by subsequent separation process. Cobalt ferrite nanoparticle, the core of magnetic silica nanocomposite, was synthesized using a thermal decomposition method and grown to a particle having an average size of 13 nm. The dispersed nanoparticles were then further arranged into spherical groups using a nanoemulsion method to enhance the reactivity toward magnets followed by tetraethyl orthosilicate coating using a modified Stöber method. The pore structure was modified by an additional coating of cetyltrimethylammonium bromide and tetraethyl orthosilicate. Finally, the surface of the magnetic silica nanocomposite was functionalized with thiol group. When tested for mercury adsorption capacity, a sufficiently high Hg adsorption capacity of 19.79 mg per g of adsorbent was obtained at room temperature and a pH of 5.5.

  12. A survey of topsoil arsenic and mercury concentrations across France.

    PubMed

    Marchant, B P; Saby, N P A; Arrouays, D

    2017-08-01

    Even at low concentrations, the presence of arsenic and mercury in soils can lead to ecological and health impacts. The recent European-wide LUCAS Topsoil Survey found that the arsenic concentration of a large proportion of French soils exceeded a threshold which indicated that further investigation was required. A much smaller proportion of soils exceeded the corresponding threshold for mercury but the impacts of mining and industrial activities on mercury concentrations are not well understood. We use samples from the French national soil monitoring network (RMQS: Réseau de Mesures de la Qualité des Sols) to explore the variation of topsoil arsenic and mercury concentrations across mainland France at a finer spatial resolution than was reported by LUCAS Topsoil. We use geostatistical methods to map the expected concentrations of these elements in the topsoil and the probabilities that the legislative thresholds are exceeded. We find that, with the exception of some areas where the geogenic concentrations and soil adsorption capacities are very low, arsenic concentrations are generally larger than the threshold which indicates that further assessment of the area is required. The lower of two other guideline values indicating risks to ecology or health is exceeded in fewer than 5% of RMQS samples. These exceedances occur in localised hot-spots primarily associated with mining and mineralization. The probabilities of mercury concentrations exceeding the further assessment threshold value are everywhere less than 0.01 and none of the RMQS samples exceed either of the ecological and health risk thresholds. However, there are some regions with elevated concentrations which can be related to volcanic material, natural mineralizations and industrial contamination. These regions are more diffuse than the hot-spots of arsenic reflecting the greater volatility of mercury and therefore the greater ease with which it can be transported and redeposited. The maps provide a

  13. Modeling mercury porosimetry using statistical mechanics.

    PubMed

    Porcheron, F; Monson, P A; Thommes, M

    2004-07-20

    We consider mercury porosimetry from the perspective of the statistical thermodynamics of penetration of a nonwetting liquid into a porous material under an external pressure. We apply density functional theory to a lattice gas model of the system and use this to compute intrusion/extrusion curves. We focus on the specific example of a Vycor glass and show that essential features of mercury porosimetry experiments can be modeled in this way. The lattice model exhibits a symmetry that provides a direct relationship between intrusion/extrusion curves for a nonwetting fluid and adsorption/desorption isotherms for a wetting fluid. This relationship clarifies the status of methods that are used for transforming mercury intrusion/extrusion curves into gas adsorption/desorption isotherms. We also use Monte Carlo simulations to investigate the nature of the intrusion and extrusion processes.

  14. Oxidation of Mercury in Products of Coal Combustion

    SciTech Connect

    Peter Walsh; Giang Tong; Neeles Bhopatkar; Thomas Gale; George Blankenship; Conrad Ingram; Selasi Blavo Tesfamariam Mehreteab; Victor Banjoko; Yohannes Ghirmazion; Heng Ban; April Sibley

    2009-09-14

    Laboratory measurements of mercury oxidation during selective catalytic reduction (SCR) of nitric oxide, simulation of pilot-scale measurements of mercury oxidation and adsorption by unburned carbon and fly ash, and synthesis of new materials for simultaneous oxidation and adsorption of mercury, were performed in support of the development of technology for control of mercury emissions from coal-fired boilers and furnaces. Conversion of gas-phase mercury from the elemental state to water-soluble oxidized form (HgCl{sub 2}) enables removal of mercury during wet flue gas desulfurization. The increase in mercury oxidation in a monolithic V{sub 2}O{sub 5}-WO{sub 3}/TiO{sub 2} SCR catalyst with increasing HCl at low levels of HCl (< 10 ppmv) and decrease in mercury oxidation with increasing NH{sub 3}/NO ratio during SCR were consistent with results of previous work by others. The most significant finding of the present work was the inhibition of mercury oxidation in the presence of CO during SCR of NO at low levels of HCl. In the presence of 2 ppmv HCl, expected in combustion products from some Powder River Basin coals, an increase in CO from 0 to 50 ppmv reduced the extent of mercury oxidation from 24 {+-} 3 to 1 {+-} 4%. Further increase in CO to 100 ppmv completely suppressed mercury oxidation. In the presence of 11-12 ppmv HCl, increasing CO from 0 to {approx}120 ppmv reduced mercury oxidation from {approx}70% to 50%. Conversion of SO{sub 2} to sulfate also decreased with increasing NH{sub 3}/NO ratio, but the effects of HCl and CO in flue gas on SO{sub 2} oxidation were unclear. Oxidation and adsorption of mercury by unburned carbon and fly ash enables mercury removal in a particulate control device. A chemical kinetic mechanism consisting of nine homogeneous and heterogeneous reactions for mercury oxidation and removal was developed to interpret pilot-scale measurements of mercury oxidation and adsorption by unburned carbon and fly ash in experiments at pilot

  15. Mercury removal from coal combustion flue gas by modified fly ash.

    PubMed

    Xu, Wenqing; Wang, Hairui; Zhu, Tingyu; Kuang, Junyan; Jing, Pengfei

    2013-02-01

    Fly ash is a potential alternative to activated carbon for mercury adsorption. The effects of physicochemical properties on the mercury adsorption performance of three fly ash samples were investigated. X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, and other methods were used to characterize the samples. Results indicate that mercury adsorption on fly ash is primarily physisorption and chemisorption. High specific surface areas and small pore diameters are beneficial to efficient mercury removal. Incompletely burned carbon is also an important factor for the improvement of mercury removal efficiency, in particular. The C-M bond, which is formed by the reaction of C and Ti, Si and other elements, may improve mercury oxidation. The samples modified with CuBr2, CuCl2 and FeCl3 showed excellent performance for Hg removal, because the chlorine in metal chlorides acts as an oxidant that promotes the conversion of elemental mercury (Hg0) into its oxidized form (Hg2+). Cu2+ and Fe3+ can also promote Hg0 oxidation as catalysts. HCl and O2 promote the adsorption of Hg by modified fly ash, whereas SO2 inhibits the Hg adsorption because of competitive adsorption for active sites. Fly ash samples modified with CuBr2, CuCl2 and FeCl3 are therefore promising materials for controlling mercury emissions.

  16. Mercury and autism: accelerating evidence?

    PubMed

    Mutter, Joachim; Naumann, Johannes; Schneider, Rainer; Walach, Harald; Haley, Boyd

    2005-10-01

    The causes of autism and neurodevelopmental disorders are unknown. Genetic and environmental risk factors seem to be involved. Because of an observed increase in autism in the last decades, which parallels cumulative mercury exposure, it was proposed that autism may be in part caused by mercury. We review the evidence for this proposal. Several epidemiological studies failed to find a correlation between mercury exposure through thimerosal, a preservative used in vaccines, and the risk of autism. Recently, it was found that autistic children had a higher mercury exposure during pregnancy due to maternal dental amalgam and thimerosal-containing immunoglobulin shots. It was hypothesized that children with autism have a decreased detoxification capacity due to genetic polymorphism. In vitro, mercury and thimerosal in levels found several days after vaccination inhibit methionine synthetase (MS) by 50%. Normal function of MS is crucial in biochemical steps necessary for brain development, attention and production of glutathione, an important antioxidative and detoxifying agent. Repetitive doses of thimerosal leads to neurobehavioral deteriorations in autoimmune susceptible mice, increased oxidative stress and decreased intracellular levels of glutathione in vitro. Subsequently, autistic children have significantly decreased level of reduced glutathione. Promising treatments of autism involve detoxification of mercury, and supplementation of deficient metabolites.

  17. Effect of functionalized groups on gas-adsorption properties: syntheses of functionalized microporous metal-organic frameworks and their high gas-storage capacity.

    PubMed

    Wang, Yanlong; Tan, Chunhong; Sun, Zhihao; Xue, Zhenzhen; Zhu, Qilong; Shen, Chaojun; Wen, Yuehong; Hu, Shengmin; Wang, Yong; Sheng, Tianlu; Wu, Xintao

    2014-01-27

    The microporous metal-organic framework (MMOF) Zn4O(L1)2⋅9 DMF⋅9 H2O (1-H) and its functionalized derivatives Zn4O(L1-CH3)2⋅9 DMF⋅9 H2O (2-CH3) and Zn4O(L1-Cl)2⋅9 DMF⋅9 H2O (3-Cl) have been synthesized and characterized (H3L1=4-[N,N-bis(4-methylbenzoic acid)amino]benzoic acid, H3L1-CH3=4-[N,N-bis(4-methylbenzoic acid)amino]-2-methylbenzoic acid, H3L1-Cl=4-[N,N-bis(4-methylbenzoic acid)amino]-2-chlorobenzoic acid). Single-crystal X-ray diffraction analyses confirmed that the two functionalized MMOFs are isostructural to their parent MMOF, and are twofold interpenetrated three-dimensional (3D) microporous frameworks. All of the samples possess enduring porosity with Langmuir surface areas over 1950 cm(2) g(-1). Their pore volumes and surface areas decrease in the order 1-H>2-CH3 >3-Cl. Gas-adsorption studies show that the H2 uptakes of these samples are among the highest of the MMOFs (2.37 wt% for 3-Cl at 77 K and 1 bar), although their structures are interpenetrating. Furthermore, this work reveals that the adsorbate-adsorbent interaction plays a more important role in the gas-adsorption properties of these samples at low pressure, whereas the effects of the pore volumes and surface areas dominate the gas-adsorption properties at high pressure.

  18. Determination of binding capacity and adsorption enthalpy between Human Glutamate Receptor (GluR1) peptide fragments and kynurenic acid by surface plasmon resonance experiments.

    PubMed

    Csapó, E; Majláth, Z; Juhász, Á; Roósz, B; Hetényi, A; Tóth, G K; Tajti, J; Vécsei, L; Dékány, I

    2014-11-01

    The interaction between kynurenic acid (KYNA) and two peptide fragments (ca. 30 residues) of Human Glutamate Receptor 201-300 (GluR1) using surface plasmon resonance (SPR) spectroscopy was investigated. Because of the medical interest in the neuroscience, GluR1 is one of the important subunits of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPAR). AMPARs are ionotoropic glutamate receptors, which are mediating fast synaptic transmission and are crucial for plasticity in the brain. On the other hand, KYNA has been suggested to have neuroprotective activity and it has been considered for apply in therapy in certain neurobiological disorders. In this article the adsorption of the GluR1201-230 and GluR1231-259 peptides were studied on gold biosensor chip. The peptides were chemically bonded onto the gold surface via thiol group of L-cysteine resulted in the formation of peptide monolayer on the SPR chip surface. Because the GluR1231-259 peptide does not contain L-cysteine the Val256 was replaced by Cys256. The cross sectional area and the surface orientation of the studied peptides were determined by SPR and theoretical calculations (LOMETS) as well. The binding capability of KYNA on the peptide monolayer was studied in the concentration range of 0.1-5.0 mM using 150 mM NaCl ionic strength at pH 7.4 (±0.02) in phosphate buffer solutions. In order to determine the binding enthalpy the experiments were carried out between +10°C and +40°C. The heat of adsorption was calculated by using adsorption isotherms at different surface loading of KYNA on the SPR chip.

  19. Mercury in mercury(II)-spiked soils is highly susceptible to plant bioaccumulation.

    PubMed

    Hlodák, Michal; Urík, Martin; Matúš, Peter; Kořenková, Lucia

    2016-01-01

    Heavy metal phytotoxicity assessments usually use soluble metal compounds in spiked soils to evaluate metal bioaccumulation, growth inhibition and adverse effects on physiological parameters. However, exampling mercury phytotoxicity for barley (Hordeum vulgare) this paper highlights unsuitability of this experimental approach. Mercury(II) in spiked soils is extremely bioavailable, and there experimentally determined bioaccumulation is significantly higher compared to reported mercury bioaccumulation efficiency from soils collected from mercury-polluted areas. Our results indicate this is not affected by soil sorption capacity, thus soil ageing and formation of more stable mercuric complexes with soil fractions is necessary for reasonable metal phytotoxicity assessments.

  20. JV Task 5 - Evaluation of Residual Oil Fly Ash As A Mercury Sorbent For Coal Combustion Flue Gas

    SciTech Connect

    Robert Patton

    2006-12-31

    The mercury adsorption capacity of a residual oil fly ash (ROFA) sample collected form Florida Power and Light Company's Port Everglades Power Plant was evaluated using a bituminous coal combustion flue gas simulator and fixed-bed testing protocol. A size-segregated (>38 {micro}g) fraction of ROFA was ground to a fine powder and brominated to potentially enhance mercury capture. The ROFA and brominated-ROFA were ineffective in capturing or oxidizing the Hg{sup 0} present in a simulated bituminous coal combustion flue gas. In contrast, a commercially available DARCO{reg_sign} FGD initially adsorbed Hg{sup 0} for about an hour and then catalyzed Hg{sup 0} oxidation to produce Hg{sup 2+}. Apparently, the unburned carbon in ROFA needs to be more rigorously activated in order for it to effectively capture and/or oxidize Hg{sup 0}.

  1. Mercury transformation behavior on a bench scale coal combustion furnace

    NASA Astrophysics Data System (ADS)

    Fujiwara, N.; Fujita, Y.; Tomura, K.; Moritomi, H.; Murakami, E.; Akimoto, A.; Ikeda, S.; Tadakuma, Y.

    2003-05-01

    The mercury release behavior in bituminous coals, and the partitioning rate of mercury in solids and gaseous in flue gases have measured to develop technologies for evaluating the partitioning of mercury in coal combustion process and develop in-situ adsorption and removal technologies using three kinds of experiment equipments - a thermo-balance, a drop-tube furnace (DTF), a bench-scale pulverized coal combustion fumace. The results showed that about 20 to 60% of the mercury in coal was released between 573K and 673K, which was the range of temperature in which the release of the volatile matter of coal began. And more than 90% of the mercury was released at 773K, the temperature at which the release of the volatile matter was completed. The rate of mercury partitioned into bottom ash in a bench-scale pulverized coal combustion furnace was the smallest irrespective of the type of coal. The rate of mercury partitioned into cyclone ash was also low for all types of coal with values generally below 10%. The rest of the mercury was partitioned into mercury in gaseous form, but the rate partitioned into dust, oxidized mercury and elemental mercury varied slightly depending on the flue gas temperature and the type of coal.

  2. Potential hazards of brominated carbon sorbents for mercury emission control.

    PubMed

    Bisson, Teresa M; Xu, Zhenghe

    2015-02-17

    Mercury is a toxic air pollutant, emitted from the combustion of coal. Activated Carbon (AC) or other carbon sorbent (CS) injection into coal combustion flue gases can remove elemental mercury through an adsorption process. Recently, a brominated CS with biomass ash as the carbon source (Br-Ash) was developed as an alternative for costly AC-based sorbent for mercury capture. After mercury capture, these sorbents are disposed in landfill, and the stability of bromine and captured mercury is of paramount importance. The objective of this study is to determine the fate of mercury and bromine from Br-Ash and brominated AC after their service. Mercury and bromine leaching tests were conducted using the standard toxicity characteristic leaching procedure (TCLP). The mercury was found to be stable on both the Br-Ash and commercial brominated AC sorbents, while the bromine leached into the aqueous phase considerably. Mercury pulse injection tests on the sorbent material after leaching indicate that both sorbents retain significant mercury capture capability even after the majority of bromine was removed. Testing of the Br-Ash sorbent over a wider range of pH and liquid:solid ratios resulted in leaching of <5% of mercury adsorbed on the Br-Ash. XPS analysis indicated more organically bound Br and less metal-Br bonds after leaching.

  3. Water adsorption at high temperature on core samples from The Geysers geothermal field

    SciTech Connect

    Gruszkiewicz, M.S.; Horita, J.; Simonson, J.M.; Mesmer, R.E.

    1998-06-01

    The quantity of water retained by rock samples taken from three wells located in The Geysers geothermal field, California, was measured at 150, 200, and 250 C as a function of steam pressure in the range 0.00 {le} p/p{sub 0} {le} 0.98, where p{sub 0} is the saturated water vapor pressure. Both adsorption and desorption runs were made in order to investigate the extent of the hysteresis. Additionally, low temperature gas adsorption analyses were made on the same rock samples. Mercury intrusion porosimetry was also used to obtain similar information extending to very large pores (macropores). A qualitative correlation was found between the surface properties obtained from nitrogen adsorption and the mineralogical and petrological characteristics of the solids. However, there was no direct correlation between BET specific surface areas and the capacity of the rocks for water adsorption at high temperatures. The hysteresis decreased significantly at 250 C. The results indicate that multilayer adsorption, rather than capillary condensation, is the dominant water storage mechanism at high temperatures.

  4. Surface mercapto engineered magnetic Fe3O4 nanoadsorbent for the removal of mercury from aqueous solutions.

    PubMed

    Pan, Shengdong; Shen, Haoyu; Xu, Qihong; Luo, Jian; Hu, Meiqin

    2012-01-01

    In this study, mercapto-functionalized nano-Fe(3)O(4) magnetic polymers (SH-Fe(3)O(4)-NMPs) have been prepared and characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), vibrating sample magnetometer (VSM), thermogravimetry and differential thermogravimetry analyses (TG-DTA), as well as Fourier-transformed infrared spectroscopy (FTIR). The adsorptive characteristics of the SH-Fe(3)O(4)-NMPs intended for removal of mercury (II) were deeply studied. The results showed that the adsorption efficiency increased with pH increasing and reached a plateau at pH above 3.0. The adsorption data obtained at the optimized condition, i.e., 308 K and pH of 3.0, were well fitted with the Freundlich isotherm. The adsorption of Hg(II) reached equilibrium within 60 min. Thermodynamic parameters such as ΔH(θ), ΔS(θ) and ΔG(θ) suggested that the adsorption processes of Hg(II) onto the SH-Fe(3)O(4)-NMPs were endothermic and entropy favored in nature, with ΔH(θ) at 30.31 kJ mol(-1), ΔS(θ) at 111.41 J mol(-1) K(-1). The effects of mercury salts, i.e., Hg(NO(3))(2), HgSO(4), and different acids, were also deeply investigated and showed that the adsorption capacity of Hg(II) onto the SH-Fe(3)O(4)-NMPs decreased when Cl(-) existed. Copyright © 2011 Elsevier Inc. All rights reserved.

  5. Sorbents for the oxidation and removal of mercury

    DOEpatents

    Olson, Edwin S.; Holmes, Michael J.; Pavlish, John H.

    2008-10-14

    A promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new modified carbon form containing reactive forms of halogen and halides. Optional components may be added to increase reactivity and mercury capacity. These may be added directly with the sorbent, or to the flue gas to enhance sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The sorbent can be regenerated and reused. Sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described.

  6. Sorbents for the oxidation and removal of mercury

    DOEpatents

    Olson, Edwin S.; Holmes, Michael J.; Pavlish, John Henry

    2014-09-02

    A promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new modified carbon form containing reactive forms of halogen and halides. Optional components may be added to increase reactivity and mercury capacity. These may be added directly with the sorbent, or to the flue gas to enhance sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The sorbent can be regenerated and reused. Sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described.

  7. Sorbents for the oxidation and removal of mercury

    DOEpatents

    Olson, Edwin S [Grand Forks, ND; Holmes, Michael J [Thompson, ND; Pavlish, John H [East Grand Forks, MN

    2012-05-01

    A promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new modified carbon form containing reactive forms of halogen and halides. Optional components may be added to increase reactivity and mercury capacity. These may be added directly with the sorbent, or to the flue gas to enhance sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The sorbent can be regenerated and reused. Sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described.

  8. Sorbents for the oxidation and removal of mercury

    DOEpatents

    Olson, Edwin S; Holmes, Michael J; Pavlish, John Henry

    2013-08-20

    A promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new modified carbon form containing reactive forms of halogen and halides. Optional components may be added to increase reactivity and mercury capacity. These may be added directly with the sorbent, or to the flue gas to enhance sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The sorbent can be regenerated and reused. Sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described.

  9. Mercury, elemental

    Integrated Risk Information System (IRIS)

    Mercury , elemental ; CASRN 7439 - 97 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

  10. Mercury's Messenger

    ERIC Educational Resources Information Center

    Chapman, Clark R.

    2004-01-01

    Forty years after Mariner 2, planetary exploration has still only just begun, and many more missions are on drawing boards, nearing the launch pad, or even en route across interplanetary space to their targets. One of the most challenging missions that will be conducted this decade is sending the MESSENGER spacecraft to orbit the planet Mercury.…

  11. Mercury Project

    NASA Image and Video Library

    1962-02-20

    Astronaut John Glenn in the Friendship 7 capsule during the first manned orbital flight, the MA-6 mission. Boosted by the Mercury-Atlas vehicle, a modified Atlas (intercontinental ballistic missile), the MA-6 mission lasted for 5 hours and orbited the Earth three times.

  12. Mercury Project

    NASA Image and Video Library

    1962-02-20

    The launch of the MA-6, Friendship 7, on February 20, 1962. Boosted by the Mercury-Atlas vehicle, a modified Atlas Intercontinental Ballistic Missile (ICBM), Friendship 7 was the first U.S. marned orbital flight and carried Astronaut John H. Glenn into orbit. Astronaut Glenn became the first American to orbit the Earth.

  13. Mercury Project

    NASA Image and Video Library

    1959-09-01

    An Atlas launch vehicle carrying the Big Joe capsule leaves its launching pad on a 2,000-mile ballistic flight to the altitude of 100 miles. The Big Joe capsule is a boilerplate model of the marned orbital capsule under NASA's Project Mercury. The capsule was recovered and studied for the effect of re-entry heat and other flight stresses.

  14. Mercury Project

    NASA Image and Video Library

    1959-04-27

    The group portrait of the original seven astronauts for the Mercury Project. NASA selected its first seven astronauts on April 27, 1959. Left to right at front: Walter M. Wally Schirra, Donald K. Deke Slayton, John H. Glenn, Jr., and Scott Carpenter. Left to right at rear: Alan B. Shepard, Virgil I. Gus Grissom, and L. Gordon Cooper, Jr.

  15. Mercury Project

    NASA Image and Video Library

    1963-05-16

    Astronaut Gordon Cooper leaves the Faith 7 (MA-9) spacecraft after a successful recovery operation. The MA-9 mission, the last flight of the Mercury Project, was launched on May 15, 1963, orbited the Earth 22 times, and lasted for 1-1/2 days.

  16. Mercury Project

    NASA Image and Video Library

    1963-05-15

    Astronaut Gordon Cooper leaves the Faith 7 (MA-9) spacecraft after a successful recovery operation. The MA-9 mission, the last flight of the Mercury Project, was launched on May 15, 1963, orbited the Earth 22 times, and lasted for 1-1/2 days.

  17. Mercury Project

    NASA Image and Video Library

    2004-04-15

    The original seven astronauts for the Mercury Project pose in front of an Air Force Jet. From left to right: Scott Carpenter, L. Gordon Cooper, John H. Glenn, Virgil I. Gus Grissom, Walter M. Wally Schirra, Alan B. Shepard, and Donald K. Deke Slayton.

  18. Mercury Project

    NASA Image and Video Library

    1960-01-21

    The launch of the Little Joe booster for the LJ1B mission on the launch pad from the wallops Flight Facility, Wallops Island, Virginia, on January 21, 1960. This mission achieved the suborbital Mercury capsule test, testing of the escape system, and biomedical tests by using a monkey, named Miss Sam.

  19. Mercury Project

    NASA Image and Video Library

    1960-01-21

    The Little Joe launch vehicle for the LJ1 mission on the launch pad at the wallops Flight Facility, Wallops Island, Virginia, on January 21, 1960. This mission achieved the suborbital Mercury cupsule test, testing of the escape system, and biomedical tests by using a monkey, named Miss Sam.

  20. Mercury's Messenger

    ERIC Educational Resources Information Center

    Chapman, Clark R.

    2004-01-01

    Forty years after Mariner 2, planetary exploration has still only just begun, and many more missions are on drawing boards, nearing the launch pad, or even en route across interplanetary space to their targets. One of the most challenging missions that will be conducted this decade is sending the MESSENGER spacecraft to orbit the planet Mercury.…

  1. Mercury Project

    NASA Image and Video Library

    1961-05-05

    Astronaut Alan Shepard underwent a physical examination prior to the first marned suborbital flight. Freedom 7 carrying Astronaut Alan Shepard, boosted by the Mercury-Redstone launch vehicle, lifted off on May 5, 1961. Astronaut Shepard became the first American in space.

  2. Mercury Project

    NASA Image and Video Library

    1961-01-01

    Astronaut Alan Shepard fitted with space suit prior to the first marned suborbital flight. Freedom 7, carrying Astronaut Alan Shepard, boosted by the Mercury-Redstone launch vehicle, lifted off on May 5, 1961. Astronaut Shepard became the first American in space.

  3. Mercury Project

    NASA Image and Video Library

    1961-05-05

    Astronaut Alan B. Shepard, Jr. during suiting for the first manned suborbital flight, MR-3 mission. The Freedom 7 spacecraft, carrying the first American, Astronaut Shepard and boosted by the Mercury-Redstone launch vehicle, lifted off on May 5, 1961.

  4. Mercury Project

    NASA Image and Video Library

    1961-05-05

    This photo depicts the recovery operations of the MR-3 mission. Astronaut Alan Shepard was picked up by a U.S. Marine helicopter after the completion of the first marned suborbital flight by MR-3 (Mercury-Redstone) with the Freedom 7 capsule.

  5. Rapid and high-capacity ultrasonic assisted adsorption of ternary toxic anionic dyes onto MOF-5-activated carbon: Artificial neural networks, partial least squares, desirability function and isotherm and kinetic study.

    PubMed

    Askari, Hanieh; Ghaedi, Mehrorang; Dashtian, Kheibar; Azghandi, Mohammad Hossein Ahmadi

    2017-07-01

    The present paper focused on the ultrasonic assisted simultaneous removal of fast green (FG), eosin Y (EY) and quin