Personal Research Database

Full Text: 2009\Wat Res43, 148.pdf

Abstract: Adsorption equilibrium and kinetics of Bacillus subtilis spores on single-walled carbon nanotube aggregates were investigated to explore the possibility of using single-walled carbon nanotubes for concentration, detection and removal of pathogens from contaminated water sources. Batch adsorption experiments were conducted to determine adsorption kinetics and adsorption equilibrium of B. subtilis spores on single-walled carbon nanotube aggregates, activated carbon and NanoCeram (TM). The adsorption kinetics data were analyzed with both the Lagergren pseudo first order and a pseudo second order models. The adsorption equilibrium data on three porous media were quantified by the Henry’s law constant. It was observed that both the Lagergren first order rate model and the pseudo second order model correlate the adsorption kinetic data well although the calculated adsorption rate constants vary with adsorbate concentrations. The Henry’s law adsorption equilibrium constant of B. subtilis spores on single-walled carbon nanotube aggregates is about 27-37 times higher than those on activated carbon and NanoCeram (TM). The high adsorption affinity of carbon nanotubes towards the B. subtilis spores is due to the mesoporous structure and unique surface properties of carbon nanotubes. These results suggest that single-walled carbon nanotube aggregates are good candidates as biosensors and adsorbent media for concentrating, detecting and removal of pathogens from contaminated water resources. (C) 2008 Elsevier Ltd. All rights reserved.

Keywords: Activated Carbon, Adsorbent, Adsorption, Adsorption Equilibrium, Adsorption Kinetics, Bacillus, Bacillus Subtilis, Bacterial-Cells, Biosensor, Biosensors, Equilibrium, Filters, Growth, Immobilization, Inactivation, Kinetics, Microorganisms, Model, Pseudo-First-Order, Pseudo-Second-Order, Removal, Single-Walled Carbon Nanotubes, Substances

? Bahdod, A., El Asri, S., Saoiabi, A., Coradin, T. and Laghzizil, A. (2009), Adsorption of phenol from an aqueous solution by selected apatite adsorbents: Kinetic process and impact of the surface properties. Water Research, 43 (2), 313-318.

Full Text: 2009\Wat Res43, 313.pdf

Abstract: Batch adsorption experiments were conducted to investigate the removal of phenol from wastewater by addition of three apatites (porous hydroxyapatite (PHAp) and crystalline hydroxyl- (HAp) and fluoroapatite (FAp)). The best performances were obtained with porous hydroxyapatite PHAp, which presented higher adsorption capacities (experimental: 8.2 mg g(-1); calculated 9.2 mg g(-1)) than HAp and FAp (3-4 mg g(-1)). Different models of adsorption were used to describe the kinetics data, to calculate corresponding rate constants and to predict the theoretical capacities of apatite surfaces for phenol adsorption. A mechanism of phenol adsorption associating chemisorption and physisorption processes is presented allowing the discussion of the variations in adsorption behavior between these materials in terms of specific surface area and chemical composition. These data suggest that apatites are promising materials for phenol sorption. (C) 2008 Elsevier Ltd. All rights reserved.

Keywords: Activated Carbon, Adsorption, Apatites, Behavior, Desorption, Hydroxyapatite, Impact, Isotherms, Kinetic, Kinetic Isotherms, Kinetics, Liquid-Phase Adsorption, Mechanism, Phenol, Phenol Removal, Proteins, Reactor, Regeneration, Removal, Sorption, Waste-Water, Wastewater

? Kumar, E., Bhatnagar, A., Ji, M., Jung, W., Lee, S.H., Kim, S.J., Lee, G., Song, H., Choi, J.Y., Yang, J.S. and Jeon, B.H. (2009), Defluoridation from aqueous solutions by granular ferric hydroxide (GFH). Water Research, 43 (2), 490-498.

Full Text: 2009\Wat Res43, 490.pdf

Abstract: This research was undertaken to evaluate the feasibility of granular ferric hydroxide (GFH) for fluoride removal from aqueous solutions, Batch experiments were performed to study the influence of various experimental parameters such as contact time (1 min-24 h), initial fluoride concentration (1-100 mg L^-1), temperature (10 and 2S°C), pH (3-12) and the presence of competing anions on the adsorption of fluoride on GFH. Kinetic data revealed that the uptake rate of fluoride was rapid in the beginning and 95% adsorption was completed within 10 min and equilibrium was achieved within 60 min. The sorption process was well explained with pseudo-first-order and pore diffusion models. The maximum adsorption capacity of GFH for fluoride removal was 7.0 mg g^-1. The adsorption was found to be an endothermic process and data conform to Langmuir model. The optimum fluoride removal was observed between pH ranges of 4-8. The fluoride adsorption was decreased in the presence of phosphate followed by carbonate and sulphate. Results from this study demonstrated potential utility of GFH that could be developed into a viable technology for fluoride removal from drinking water. (C) 2008 Elsevier Ltd. All rights reserved.

Keywords: Activated Alumina, Adsorption Isotherms, Chemical-Model, Competing Anions, Defluoridation, Diffusion, Fluoride Ions, Granular Ferric Hydroxide (GFH), Kinetic Modeling, Kinetics, pH, Phosphate Adsorption, Physicochemical Characterization, Removal, Temperature Effect, Waste-Water, Water-Treatment

? Yu, Q., Zhang, R.Q., Deng, S.B., Huang, J. and Yu, G. (2009), Sorption of perfluorooctane sulfonate and perfluorooctanoate on activated carbons and resin: Kinetic and isotherm study. Water Research, 43 (4), 1150-1158.

Full Text: 2009\Wat Res43, 1150.pdf

Abstract: Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) have increasingly attracted global concerns in recent years due to their global distribution, persistence, strong bioaccumulation and potential toxicity. The feasibility of using powder activated carbon (PAC), granular activated carbon (GAC) and anion-exchange resin (AI400) to remove PFOS and PFOA from water was investigated with regard to their sorption kinetics and isotherms. Sorption kinetic results show that the adsorbent size influenced greatly the sorption velocity, and both the GAC and AI400 required over 168 h to achieve the equilibrium, much longer than 4 h for the PAC. Two kinetic models were adopted to describe the experimental data, and the pseudo-second-order model well described the sorption of PFOS and PFOA on the three adsorbents. The sorption isotherms show that the GAC had the lowest sorption capacity both for PFOS and PFOA among the three adsorbents, while the PAC and AI400 possessed the highest sorption capacity of 1.04 mmol g^-1 for PFOS and 2.92 mmol g^-1 for PFOA according to the Langmuir fitting. Based on the sorption behaviors and the characteristics of the adsorbents and adsorbates, ion exchange and electrostatic interaction as well as hydrophobic interaction were deduced to be involved in the sorption, and some hemi-micelles and micelles possibly formed in the intraparticle pores. (C) 2008 Elsevier Ltd. All rights reserved.

Keywords: Activated Carbon, Anion-Exchange Resin, Aqueous-Solution, Chitosan, Defluorination, Isotherm, Kinetic, Kinetics, Liquid-Phase Adsorption, Perfluorinated Surfactants, PFOA, PFOS, Reactive Dyes, Removal, Reverse-Osmosis, Sorption Isotherm, Sorption Kinetics, Waste-Water

? Rentz, J.A., Turner, I.P. and Ullman, J.L. (2009), Removal of phosphorus from solution using biogenic iron oxides. Water Research, 43 (7), 2029-2035.

Full Text: 2009\Wat Res43, 2029.pdf

Abstract: Phosphorus removal by biogenic iron oxides was investigated, providing an initial characterization of a potentially regenerable iron-rich sorbent. The biogenic iron oxides were collected from a wetland ecosystem and were dominated by the sheaths of Leptothrix ochracea. Sorption kinetics followed a pseudo-1st order model (R² = 0.998) with a rate constant of 0.154±0.013 h(-1). The Langmuir isotherm adequately described sorption for all samples (R² = 0.923-0.981); the Freundlich model was a better fit for only one of four samples. Maximum phosphorus sorption estimated using the Langmuir parameter ranged from 46.9±2.9 to 165.0±21.2 mg P/g Fe and was similar to other iron-rich substrates. Maximum sorption normalized to total solids ranged from 10.8±0.7 to 39.9±3.2 mg P/g, which represented the highest published values for iron-rich substrates. The high sorption capacity with respect to both iron and solids warrants further evaluation of biogenic iron oxides as a substrate for phosphorus removal. (C) 2009 Elsevier Ltd. All rights reserved.

Keywords: Biofilm, Circumneutral Ph, Enhanced Secondary-Treatment, Isotherm, Kinetics, Media, Municipal Waste-Water, Oxidation, Oxidizing Bacteria, Particles, Phosphate Adsorption, Reactive Filtration, Regenerable, Sorption, Sorption, Stormwater, Sustainable, Wastewater

? Putra, E.K., Pranowo, R., Sunarso, J., Indraswati, N. and Ismadji, S. (2009), Performance of activated carbon and bentonite for adsorption of amoxicillin from wastewater: Mechanisms, isotherms and kinetics. Water Research, 43 (9), 2419-2430.

Full Text: 2009\Wat Res43, 2419.pdf

Abstract: Amoxicillin’s traces within pharmaceutical effluents have toxic impact toward the algae and other lower organisms within food web. Adsorption, as an efficient process to remove contaminants from water was chosen; in particular with bentonite and activated carbon as adsorbents. The study was carried out at several pH values. Langmuir and Freundlich models were then employed to correlate the equilibria data on which both models equally well-fit the data. For kinetic data, pseudo-first and second order models are selected. While chemisorption is the dominant adsorption mechanism on the bentonite case, both physisorption and chemisorption play important roles for adsorption onto activated carbon. Also, several possible mechanisms for these adsorption systems were elaborated further. (C) 2009 Elsevier Ltd. All rights reserved.

Keywords: Activated Carbon, Adsorption, Algal Toxicity, Amoxicillin, Antibacterial Agents, Antibiotics, Environment, Fate, Kinetics, Mechanism, Models, Removal, Wastewaters

? Hernández-Soriano, M.C., Mingorance, M.D. and Peña, A. (2009), Dissipation of insecticides in a Mediterranean soil in the presence of wastewater and surfactant solutions. A kinetic model approach. Water Research, 43 (9), 2481-2492.

Full Text: 2009\Wat Res43, 2481.pdf

Abstract: The simultaneous disappearance of four organophosphorous insecticides in a Mediterranean calcareous soil was evaluated in the presence of surfactant solutions and municipal wastewater. A cationic, an anionic and a non-ionic surfactant were used at a low (0.75 mg L(-1)) and at a high (twice the critical micelle concentration) concentration level. The cationic surfactant was also studied at a higher concentration. Dissipation in control soil was rapid for malathion (half-life 4 days), intermediate for dimethoate and methidathion (ca. 6 days) and slow for diazinon (29 days). Wastewater did either not modify (diazinon, dimethoate and methidathion) or slightly enhance (malathion) insecticide decay. The increase in concentration of the non-ionic surfactant Tween 80 resulted in enhanced dissipation rates for all the pesticides except diazinon. The addition of the anionic surfactant did not show a clear trend. At the highest cationic surfactant concentration a reduction of pesticide disappearance occurred linked with a reduced availability, since the insecticides were retained on the surfactant-modified soil (final residual concentration of 85% for diazinon and approximate to 55% for methidathion and dimethoate). Soil microbial activity, estimated by measuring dehydrogenase activity, was low in wastewater- and surfactant-treated soil at the high levels. Fitting of the experimental data to commonly used mathematical models was poor and alternatives were looked for. (C) 2009 Elsevier Ltd. All rights reserved.

Keywords: Atrazine, Bi-Phasic Kinetic Models, Cationic Surfactant, Control, Degradation, Enhanced Desorption, Insecticides, Model, Organic Amendments, Organophosphorus Pesticides, Persistence, Pesticides, Samples, Sewage-Sludge, Sorption, Surfactants, Trend, Triton X-100, Wastewater

? Li, Y.J., Gao, B.Y., Wu, T., Sun, D.J., Li, X., Wang, B. and Lu, F.J. (2009), Hexavalent chromium removal from aqueous solution by adsorption on aluminum magnesium mixed hydroxide. Water Research, 43 (12), 3067-3075.

Full Text: 2009\Wat Res43, 3067.pdf

Abstract: A series of sols consisting of aluminum magnesium mixed hydroxide (AMH) nanoparticles with various Mg/Al molar ratios were prepared by coprecipitation. The use of AMH as adsorbent to remove Cr(VI) from aqueous solution was investigated. Adsorption experiments were carried out as a function of the Mg/Al molar ratio, pH, contact time, concentration of Cr(VI) and temperature. It was found that AMH with Mg/Al molar ratio 3 has the largest adsorption efficiency due to the smallest average particle diameter and the highest zeta potential; AMH was particularly effective for the Cr(VI) removal in a pH range from acid to slightly alkaline, even though the most effective pH range was between 2.5 and 5.0. The adsorption of Cr(VI) on AMH reached equilibrium within 150 min. The saturated adsorption capacities of AMH for Cr(VI) were 105.3-112.0 mg/g at 20-40C. The interaction between the surface sites of AMH and the Cr(VI) ions may be a combination of both anion exchange and surface complexation. The pseudo-second-order model best described the adsorption kinetics of Cr(VI) onto AMH. The results showed that AMH can be used as a new adsorbent for Cr(VI) removal which has higher adsorption capacity and faster adsorption rate at pH values close to that at which pollutants are usually found in the environment. (C) 2009 Elsevier Ltd. All rights reserved.

Keywords: Adsorbent, Adsorption, Adsorption Capacities, Adsorption Capacity, Adsorption Kinetics, Adsorption Rate, Aluminum, Aluminum Magnesium Mixed, Aqueous Solution, Capacity, Chromate, Chromium, Chromium Removal, Complexation, Concentration, Coprecipitation, Cr(VI), Efficiency, Environment, Equilibrium, Experiments, Function, Hexavalent Chromium, Hydrotalcite-Like Compounds, Hydroxide, Interaction, Ion-Exchange, Ions, Kinetics, Kinetics, Layered Double Hydroxides, Magnesium, Mechanisms, Mg-Al-CO₃ Hydrotalcite, Model, Nanoparticles, pH, Pollutants, Potential, Pseudo Second Order, Pseudo-Second-Order, Pseudo-Second-Order Model, Removal, Rights, Solution, Sorption, Surface, Surface Complexation, Temperature, Zeta Potential

? Matsui, Y., Ando, N., Sasaki, H., Matsushita, T. and Ohno, K. (2009), Branched pore kinetic model analysis of geosmin adsorption on super-powdered activated carbon. Water Research, 43 (12), 3095-3103.

Full Text: 2009\Wat Res43, 3095.pdf

Abstract: Super-powdered activated carbon (S-PAC) is activated carbon of much finer particle size than powdered activated carbon (PAC). Geosmin is a naturally occurring taste and odor compound that impairs aesthetic quality in drinking water. Experiments on geosmin adsorption on S-PAC and PAC were conducted, and the results using adsorption kinetic models were analyzed. PAC pulverization, which produced the S-PAC, did not change geosmin adsorption capacity, and geosmin adsorption capacities did not differ between SPAC and PAC. Geosmin adsorption kinetics, however, were much higher oil S-PAC than on PAC. A solution to the branched pore kinetic model (BPKM) was developed, and experimental adsorption kinetic data were analyzed by BPKM and by a homogeneous surface diffusion model (HSDM). The HSDM describing the adsorption behavior of geosmin required different surface diffusivity values for S-PAC and PAC, which indicated a decrease in surface diffusivity apparently associated with activated carbon particle size. The BPKM, consisting of macropore diffusion followed by mass transfer from macropore to micropore, successfully described the batch adsorption kinetics on S-PAC and PAC with the same set of model parameter values, including surface diffusivity. The BPKM simulation clearly showed geosmin removal was improved as activated carbon particle size decreased. The simulation also implied that the rate-determining step in overall mass transfer shifted from intraparticle radial diffusion in macropores to local mass transfer from macropore to micropore. Sensitivity analysis showed that adsorptive removal of geosmin improved with decrease in activated carbon particle size down to I pm, but further particle size reduction produced little improvement. (C) 2009 Elsevier Ltd. All rights reserved.

Keywords: 2-Methylisoborneol, Activated Carbon, Adsorber, Adsorption, Adsorption Kinetics, Analysis, Behavior, Capacity, Diffusion, Drinking Water, Equilibrium, Geosmin, HSDM, Kinetic Models, Kinetics, Mechanism, Model, Natural Organic-Matter, PAC, Particle Size, Particles, Removal, Sorption, Submicron, Taste and Odor, Waters

? Jang, M., Cannon, F.S., Parette, R.B., Yoon, S.J. and Chen, W.F. (2009), Combined hydrous ferric oxide and quaternary ammonium surfactant tailoring of granular activated carbon for concurrent arsenate and perchlorate removal. Water Research, 43 (12), 3133-3143.

Full Text: 2009\Wat Res43, 3133.pdf

Abstract: Activated carbon was tailored with both iron and quaternary ammonium surfactants so as to concurrently remove both arsenate and perchlorate from groundwater. The iron (hydr)oxide preferentially removed the arsenate oxyanion but not perchlorate; while the quaternary ammonium preferentially removed the perchlorate oxyanion, but not the arsenate. The co-sorption of two anionic oxyanions via distinct mechanisms has yielded intriguing phenomena. Rapid small-scale column tests (RSSCTs) with these dually prepared media employed synthetic waters that were concurrently spiked with arsenate and Perchlorate; and these trial results showed that the quaternary ammonium surfactants enhanced arsenate removal bed life by 25-50% when compared to activated carbon media that had been preloaded merely with iron (hydr)oxide; and the surfactant also enhanced the diffusion rate of arsenate per the Donnan effect. The authors also employed natural groundwater from Rutland, MA which contained 60 g/L As and traces of silica, and sulfate; and the authors spiked this with 40 g/L Perchlorate. When processing this water, activated carbon that had been tailored with iron and cationic surfactant could treat 12,500 bed volumes before 10 g/L arsenic breakthrough, and 4500 bed volumes before 6 g/l, Perchlorate breakthrough. Although the quaternary ammonium surfactants exhibited only a slight capacity for removing arsenate, these surfactants did facilitate a more favorably positively charged avenue for the arsenate to diffuse through the media to the iron sorption site (i.e. via the Donnan effect). (C) 2009 Published by Elsevier Ltd.

Keywords: Activated Carbon, Adsorption, Ammonium, Aqueous-Solution, Arsenate, Arsenate Removal, Arsenic, Arsenic and Perchlorate, Authors, Breakthrough, Capacity, Carbon, Cationic Surfactant, Cationic Surfactants, Column, Column Tests, Diffusion, Equilibrium, Ferric Oxide, Granular Activated Carbon, Groundwater, Hydrous Ferric Oxide, Hydroxide GFH, Iron, Iron-Oxides, Life, Mechanisms, Media, Micellar-Enhanced Ultrafiltration, Natural, Oxide, Perchlorate, Removal, Silica, Site, Sorption, Speciation, Sulfate, Surfactant, Surfactants, Trial, Water, Waters, XANES Spectroscopy

? Kurniawan, T.A. and Lo, W.H. (2009), Removal of refractory compounds from stabilized landfill leachate using an integrated H₂O₂ oxidation and granular activated carbon (GAC) adsorption treatment. Water Research, 43 (16), 4079-4091.

Full Text: 2009\Wat Res43, 4079.pdf

Abstract: This study investigated the treatment performances of H2O2 oxidation alone and its combination with granular activated carbon (GAC) adsorption for raw leachate from the NENT landfill (Hong Kong) with a very low biodegradability ratio (BODS/COD) of 0.08. The COD removal of refractory compounds (as indicated by COD values) by the integrated H2O2 and GAC treatment was evaluated, optimized and compared to that by H2O2 treatment alone with respect to dose, contact time, pH, and biodegradability ratio. At an initial COD concentration of 8000 mg/L and NH3-N of 2595 mg/L, the integrated treatment has substantially achieved a higher removal (COD: 82%; NH3-N: 59%) than the H2O2 oxidation alone (COD: 33%; NH3-N: 4.9%) and GAC adsorption alone (COD: 58%) at optimized experimental conditions (p <= 0.05; t-test). The addition of an Fe(II) dose at 1.8 g/L further improved the removal of refractory compounds by the integrated treatment from 82% to 89%. Although the integrated H2O2 oxidation and GAC adsorption could treat leachate of varying strengths, treated effluents were unable to meet the local COD limit of less than 200 mg/L and the NHYN of lower than 5 mg/L. However, the integrated treatment significantly improved the biodegradability ratio of the treated leachate by 350% from 0.08 to 0.36, enabling the application of subsequent biological treatments for complementing the degradation of target compounds in the leachate prior to their discharge. (C) 2009 Elsevier Ltd. All rights reserved.

Keywords: 4-Chlorophenol, Activated Carbon, Adsorption, Advanced Oxidation Process (AOP), Application, Aqueous-Solution, Biological, Carbon, Catalytic Decomposition, Chemical Precipitation, Cod, Concentration, Degradation, Discharge, Effluents, Environmental Protection, Experimental, Fenton’s Oxidation, GAC, Granular Activated Carbon, H₂O₂, Hong Kong, Hydrogen-Peroxide, Landfill, Landfill Leachate, Landfill Leachate Treatment, Leachate, Local, NH₃-N, Optimization, Oxidation, Ozone, pH, Recalcitrant Compounds, Removal, Reverse-Osmosis, Rights, Si, Solid Waste Management, Treatment, Wastewater Treatment, Water

? Chan, Y.T., Kuan, W.H., Chen, T.Y. and Wang, M.K. (2009), Adsorption mechanism of selenate and selenite on the binary oxide systems. Water Research, 43 (17), 4412-4420.

Full Text: 2009\Wat Res43, 4412.pdf

Abstract: Removal of selenium oxyanions by the binary oxide systems, Al- or Fe-oxides mixed with X-ray noncrystalline SiO₂, was previously not well understood. This study evaluates the adsorption capacity and kinetics of selenium oxyanions by different metal hydroxides onto SiO₂, and uses X-ray absorption spectroscopy (XAS) to assess the interaction between selenium oxyanions and the sorbents at pH 5.0. The binary oxide systems of Al(III)- or Fe(III)-oxides mixed with SiO₂ were prepared, and were characterized for their surface area, point of zero charge (PZC), pH envelopes, X-ray diffraction analysis (XRD), and then macroscale adsorption isotherm and kinetics of selenite and selenate, micro-scale adsorption XAS. The adsorption capacity of selenite and selenate on Al(III)/SiO₂ is greater than on Fe(III)/SiO₂. Adsorption isothermal and kinetic data of selenium can be well fitted to the Langmuir isotherm and pseudo-second-order kinetic models. Based on simple geometrical constraints, selenite on both the binary oxide systems forms bidentate inner-sphere surface complexes, and selenate on Fe(III)/SiO₂ forms stronger complexes than on Al(III)/SiO₂. (c) 2009 Elsevier Ltd. All rights reserved.

Keywords: Absorption, Adsorption, Adsorption Capacity, Adsorption Isotherm, Adsorption Mechanism, Analysis, Binary Oxide Systems, Capacity, Charge, Coated Sand, Data, Forms, Interaction, Isotherm, Isothermal, Kinetic, Kinetic Models, Kinetics, Langmuir, Langmuir Isotherm, Mechanism, Metal, Mixed Oxides, Models, Oxide, Oxyanions, pH, Point of Zero Charge, Pseudo Second Order, Pseudo-Second-Order, Pseudo-Second-Order Kinetic Model, Removal, Rights, Selenate, Selenium, Selenium Oxyanions, Silicic-Acid, Sorbents, Spectroscopy, Sulfate Adsorption, Surface, Surface Area, Surface Complexes, Systems, Water, X-Ray, X-Ray Absorption Spectroscopy, X-Ray Absorption Spectroscopy (XAS), X-Ray Diffraction, X-Ray-Absorption, XAS, XRD

? Hale, S.E., Tomaszewski, J.E., Luthy, R.G. and Werner, D. (2009), Sorption of dichlorodiphenyltrichloroethane (DDT) and its metabolites by activated carbon in clean water and sediment slurries. Water Research,