Personal Research Database

Full Text: 2007\Sep Pur Tec57, 161.pdf

Abstract: This study puts forward a novel method to prepare granular red mud (GRM) and evaluates its potential use to remove cadmium ions from aqueous solutions as a low-cost adsorbent. The properties of the novel adsorbent were examined and then used for cadmium adsorption experiments. Batch experiments were conducted and equilibrium isotherms at different temperatures (20°C, 30°C, 40°C) have been determined and analyzed with a Freundlich model. Kinetics data at initial pH 6.0 and 3.0 were fitted with Pseudo-second-order model and external mass transfer coefficients, effective particle diffusion coefficients were subsequently calculated for cadmium-GRM system at initial pH 6.0. Column breakthrough curves were depicted and the data were analyzed with a Thomas model. The column adsorption was reversal and the regeneration operation was accomplished by pumping 0.1 mol/L hydrochloric acid through the adsorbed column. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Acid, Adsorbent, Adsorption, Aqueous Solutions, Breakthrough, Breakthrough Curves, Cadmium, Cadmium Adsorption, Cadmium Ions, Cd(II), Column, Column Adsorption, Copper(II), Diffusion, Diffusion Coefficients, Dye, Effective, Equilibrium, Equilibrium Isotherms, Experiments, External Mass Transfer, Freundlich, Freundlich Model, Granular, Granular Red Mud, GRM, Heavy-Metals, Hydrochloric Acid, Ions, Isotherms, Kinetics, Low Cost Adsorbent, Low-Cost Adsorbent, Mass, Mass Transfer, Mass Transfer Coefficients, Mass-Transfer, Method, Model, Mud, Operation, Particle, Particle Diffusion, pH, Potential, Properties, Red Mud, Regeneration, Sawdust, Solutions, Sorption, Temperatures, Thomas, Thomas Model, Transfer, Waste

? Jacques, R.A., Lima, E.C., Dias, S.L.R., Mazzocato, A.C. and Pavan, F.A. (2007), Yellow passion-fruit shell as biosorbent to remove Cr(III) and Pb(II) from aqueous solution. Separation and Purification Technology, 57 (1), 193-198.

Full Text: 2007\Sep Pur Tec57, 193.pdf

Abstract: In the present study we reported by the first time the feasibility of yellow passion-fruit shell (YPFS- Passiflora edulis Sims. f. flavicarpa Degener) as an alternative biosorbent to remove Cr(III) and Pb(II) metallic ions from aqueous solutions. The ability of YPFS to remove Cr(III) and Pb(II) was investigated by using batch biosorption procedure. The effects such as contact time and pH on the biosorption capacities were studied. The biosorption kinetics followed the pseudo second-order kinetic model, obtaining the following biosorption constant rates, 1.4810^-2 and 4.7010^-3 g mg^-1 min^-1 using a 5.0 mg l^-1 metallic ion solution, for Cr(III) and Pb(II), respectively. The maximum biosorption capacity of YPFS were 85.1 and 151.6 mg g^-1 for Cr(III) and Pb(II), respectively. This high biosorption capacity of YPFS places this biosorbent as one of the best biosorbents for removal or Cr(III) and Pb(II) from aqueous effluents. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Aqueous Solution, Aqueous Solutions, Batch, Batch Biosorption, Batch Conditions, Biosorbent, Biosorbents, Biosorption, Biosorption, Biosorption Capacities, Biosorption Capacity, Biosorption Kinetics, Capacity, Chromium, Contact Time, Cr(III), Effects, Effluents, Heavy-Metals, Industrial-Waste, Ion, Isotherms Model, Kinetic, Kinetic Model, Kinetic of Biosorption, Kinetics, L(1), Lead, Low-Cost Adsorbent, Low-Cost Sorbents, Mandarin Peels, Metallic, Metallic Ions, Model, Pb(II), pH, Pseudo Second Order, Pseudo Second Order Kinetic, Pseudo Second-Order, Pseudo-Second-Order, Removal, Second Order, Shell, Solutions, Statistical Design, Time, Toxic Metals, Yellow Passion-Fruit Shell

? Zheng, K., Pan, B., Zhang, Q., Zhang, W.M., Pan, B.J., Han, Y.H., Zhang, Q.R., Wei, D., Cu, Z.W. and Zhang, Q.X. (2007), Enhanced adsorption of p-nitroaniline from water by a carboxylated polymeric adsorbent. Separation and Purification Technology, 57 (2), 250-256.

Full Text: 2007\Sep Pur Tec57, 250.pdf

Abstract: In the present study a carboxylated polymeric adsorbent ZK-1 was synthesized for enhanced removal of p-nitroaniline (PNA) from aqueous solution. A commercial polymeric adsorbent XAD-4 was selected for comparison purpose. Characterization of ZK- I was characterized by infrared spectroscopy and pore size distribution analysis. Experimental results showed that PNA adsorption onto ZK- I was greatly enhanced due to its micropore structure and the carboxylic group introduced onto polymeric matrix. Different pH-dependent adsorption tendency of PNA onto XAD-4 and ZK- I was observed mainly due to the role of carboxyl group on the ZK- I surface. Isotherms of PNA adsorption onto ZK- I and XAD-4 could be represented by Langmuir model reasonably. More favorable PNA adsorption onto ZK- I than X AD-4 was further demonstrated by thermodynamic ananlysis. Kinetic studies demonstrated that PNA uptake onto ZK-1 followed the pseudo-second order model, while that onto XAD-4 would be more suitably represented by the pseudo-first order model. Column adsorption runs indicated that PNA could be completely removed from aqueous system by ZK-1. Moreover, efficient regeneration of the spent adsorbent ZK- I was readily achieved by ethanol and water for its repeated use. (C) 2007 Elsevier B.V. All rights reserved.

Keywords: 4-Nitroaniline, Activated Carbon, Adsorbent, Adsorption, Adsorption Enhancement, Analysis, Aqueous Solution, Aqueous-Solutions, Breakthrough Curves, Carboxyl, Carboxyl Group, Carboxylation, Chlorophenols, Comparison, Distribution, Ethanol, Exchange Resins, Group, Infrared Spectroscopy, Kinetics, Langmuir, Langmuir Model, Matrix, Micropore, Model, Order, Phenolic-Compounds, Polymeric, Polymeric Adsorbent, Pore, Pore Size, Pore Size Distribution, Pseudo Second Order, Pseudo-First Order, Pseudo-First-Order, Pseudo-Second Order, Pseudo-Second Order Model, Pseudo-Second-Order, Regeneration, Removal, Role, Size, Size Distribution, Size Distribution Analysis, Sorbents, Spectroscopy, Structure, Surface, Thermodynamic, Uptake, Waste-Water, Water, XAD-4

? Rao, R.A.K. and Khan, M.A. (2007), Removal and recovery of Cu(II), Cd(II) and Pb(II) ions from single and multimetal systems by batch and column operation on neem oil cake (NOC). Separation and Purification Technology, 57 (2), 394-402.

Full Text: 2007\Sep Pur Tec57, 394.pdf

Abstract: NOC, a byproduct obtained after extraction of oil from neem fruit was used as an adsorbent for the removal of Pb(II) from wastewater. The adsorption of Pb(II) was found to be maximum (98%) at pH 4. The lower value of Langmuir constant (b) indicates strong binding of Pb(II) on NOC surface. The Freundlich constant n indicates beneficial adsorption. Thermodynamic parameters (H° and G°) suggest endothermic and spontaneous process. Kinetic studies show better applicability of second order kinetic model. The practical utility of NOC was demonstrated by removing Pb(II) along with Cd(II) and Cu(II) from single metal and multimetal systems by batch and column process. It was found that removal efficiency of NOC was better by column operation in multimetal system. The breakthrough capacities of Cu(II), Cd(II) and Pb(II) on NOC are found to be 10, 15 and 30 mg/g, respectively. (C) 2007 Elsevier B.V. All rights reserved.

Keywords: Adsorbent, Adsorption, Adsorption, Batch, Binding, Biomass, Biosorption Equilibria, Breakthrough, Breakthrough Capacity, Cadmium, Cake, Cd(II), Column, Column Operation, Copper, Cu(II), Efficiency, Endothermic, Extraction, Freundlich, Fruit, G, Heavy-Metals, Ions, Kinetic, Kinetic Model, Kinetics, Langmuir, Lead, Metal, Model, Multimetal System, Oil, Operation, Order, Parameters, Pb(II), Pb(II) Ions, P, Process, Recovery, Removal, Removal Efficiency, Removing, Second Order, Sorption, Spontaneous, Surface, Thermodynamics, Utility, Value, Waste-Water, Wastewater, Zinc

? Wang, S.G., Gong, W.X., Liu, X.W., Yao, Y.W., Gao, B.Y. and Yue, Q.Y. (2007), Removal of lead(II) from aqueous solution by adsorption onto manganese oxide-coated carbon nanotubes. Separation and Purification Technology, 58 (1), 17-23.

Full Text: 2007\Sep Pur Tec58, 17.pdf

Abstract: Mn oxide-coated carbon nanotubes (MnO₂/CNTs) were prepared and used to remove Pb(II) from aqueous solution. The XRD revealed that MnO₂ covered MnO₂/CNTs was an amorphous phase. The Pb(II) removal capacity of MnO₂/CNTs decreased with the decrease of pH. From the Langmuir isotherms, maximum adsorption capacity (Q(0)) of MnO₂/CNTs towards Pb(II) was determined (Q(0) = 78.74 mg/g). Comparing with CNTs, significant improvement of Pb(II) adsorption shows MnO₂/CNTs can be good Pb(II) absorbers. Although Pb(II) adsorption by MnO₂/CNTs occurred rapidly within the first 15 min of contact time, contact time needed at least 2 It in order to attain adsorption equilibrium and the kinetic adsorption can be described by the pseudo-second-order rate equation. Thermodynamics of Pb(II) was studied at various temperatures of 283, 303 and 323 K and the thermodynamic parameters were also determined. (c) 2007 Published by Elsevier B.V.

Keywords: Adsorption, Cadmium Removal, Carbon Nanotubes, Chitin, Column, Copper(II), Equilibrium, Fixed-Bed, Granular Activated Carbon, Heavy-Metals, Manganese Oxide Coated, Pb(II), Water, Zeolite

? Liu, P. and Zhang, L.X. (2007), Adsorption of dyes from aqueous solutions or suspensions with clay nano-adsorbents. Separation and Purification Technology, 58 (1), 32-39.

Full Text: 2007\Sep Pur Tec58, 32.pdf

Abstract: The increasing use of organic compounds endangering the environment encourages search for more efficient adsorbents. Clays are natural environment-friendly materials with high specific surface area and now widely used for the adsorption and removal of the organic pollutants. In the present review, the adsorption properties of the raw clays, activated clays by acid-treatment or calcinations, organic-modified clays with small molecules or polymers for the adsorption and removal of organic dyes from aqueous solutions are reviewed. The development perspectives are also proposed. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Organic Dyes, Clay Nano-Adsorbent, Review, Cationic Cyanine Dye, Solid Thin-Films, Methylene-Blue, Rhodamine 6G, Acid Dye, Activated Montmorillonite, Absorption-Spectroscopy, Polymer Nanocomposites, Model-Calculations, Interlayer Space

? Stafiej, A. and Pyrzynska, K. (2007), Adsorption of heavy metal ions with carbon nanotubes. Separation and Purification Technology, 58 (1), 49-52.

Full Text: 2007\Sep Pur Tec58, 49.pdf

Abstract: Carbon nanotubes (CNTs) were employed as adsorbent to study the adsorption characteristics of some divalent metal ions (Cu, Co, Cd, Zn, Mn, Pb). The effect of solution conditions such as pH and metal ions concentration was investigated. At pH 9 the affinity order of the metal ions towards CNTs is Cu(II) > Pb(II) > Co(II) > Zn(II) > Mn(II). The Freundlich adsorption model agrees well with experimental data. Our results suggest that CNTs have good potential application in environmental protection. (c) 2007 Published by Elsevier B.V.

Keywords: Carbon Nanotubes, Adsorption, pH Effect, Heavy Metal Ions, Preconcentration, Removal, Sorbents, Water, Pb²⁺

? Rao, G.P., Lu, C. and Su, F. (2007), Sorption of divalent metal ions from aqueous solution by carbon nanotubes: A review. Separation and Purification Technology, 58 (1), 224-231.

Full Text: 2007\Sep Pur Tec58, 224.pdf

Abstract: In this article, the technical feasibility of various kinds of raw and surface oxidized carbon nanotubes (CNTs) for sorption of divalent metal ions (Cd²⁺, CU²⁺, Ni²⁺, Pb²⁺, Zn²⁺) from aqueous solution is reviewed. The sorption mechanisms appear mainly attributable to chemical interactions between the metal ions and the surface functional groups of the CNTs. The sorption capacities of CNTs remarkably increased after oxidized by NaOCl, HNO₃ and KMnO₄ solutions and such surface oxidized CNTs show great potential as superior sorbents for environmental protection applications. Effects of process parameters, such as CNT characterizations (surface area, pore size distribution, sorbent mass, and surface total acidity), solution properties (ionic strength, pH, initial sorbate concentration and temperature) and competition for sorption sites by multiple metal ions, on the performance of CNTs are addressed in some detail. The recovery of metal ions and the regeneration of CNTs can be achieved using acid elution with little effect on the CNT performance. The utilization of CNTs for the treatment of water and wastewater containing divalent metal ions is gaining more attention as a simple and effective means of pollution control. Future research works on developing a cost-effective way of CNT production and testing the toxicity of CNTs and CNT-related materials are recommended. (C) 2007 Elsevier B.V. All rights reserved.

Keywords: Carbon Nanotubes, Chemical Treatment, Heavy Metal Ions, Sorption, Anodic-Stripping Voltammetry, Activated Carbon, Equilibrium Adsorption, Lead(II) Ions, Heavy-Metals, Waste-Water, Fly-Ash, Removal, Biosorption, Adsorbent

? Mohanty, K., Das, D. and Biswas, M.N. (2008), Treatment of phenolic wastewater in a novel multi-stage external loop airlift reactor using activated carbon. Separation and Purification Technology, 58 (3), 311-319.

Full Text: 2008\Sep Pur Tec58, 311.pdf

Abstract: In this work, a novel multi-stage external loop airlift reactor has been designed to remove phenol from wastewater by means of its adsorption onto the surface of activated carbons. The multi-staging has been achieved by hydrodynamically induced continuous bubble generation, breakup and regeneration. The continuous rupture and bursting of bubbles creates localized turbulence and recirculation, which helps in faster transfer of trace pollutants to the active sites of the solid adsorbents. Thus, the pollutants get adsorbed to the surface of the solid adsorbents due to continuous agitation. Different operating parameters that affect the performance of the reactor are the superficial gas velocity, liquid circulation velocity, concentration of the pollutant present in wastewater, contact time and the carbon loading. The results show that the removal time as well as the activated carbon loading for this system were quite lower as compared to simple batch adsorption systems. The kinetic data were fitted to the models of intra-particle diffusion, pseudo-second-order and Lagergren, and followed more closely the Lagergren pseudo-first-order model. Langmuir and Freundlich models were used to study the adsorption isotherms. A correlation has been developed to predict the efficiency of percentage removal of phenol and found to be highly significant from statistical point of view. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Adsorbents, Adsorption, Adsorption, Adsorption Isotherms, Carbon, Diffusion, Intra-Particle Diffusion, Isotherms, Kinetic, Kinetics, Langmuir, Multi-Stage External Loop Airlift Reactor, Phenol, Phenol Removal, Removal, Scrubber, Wastewater, Wastewater Treatment

? Kim, S.H., Ngo, H.H., Shon, H.K. and Vigneswaran, S. (2008), Adsorption and photocatalysis kinetics of herbicide onto titanium oxide and powdered activated carbon. Separation and Purification Technology, 58 (3), 335-342.

Full Text: 2008\Sep Pur Tec58, 335.pdf

Abstract: The adsorption and photocatalysis kinetics of metsulfuron-methyl (MM) onto titanium oxide (TiO₂) and powdered activated carbon (PAC) were studied at varying adsorbent amount and MM concentration. The overall mass transfer in adsorption was estimated from concentration decay curves obtained in the batch adsorber. The maximum adsorption capacity decreased with increasing adsorbent amount in TiO₂ adsorption. The adsorption isotherms of MM could be plotted using the Langmuir isotherm model with a reasonable degree of accuracy having higher r² values rather than Freundlich isotherm model. Linear driving force approximation (LDFA) kinetic equation with Langmuir adsorption isotherm model was successfully applied to predict the adsorption kinetics data in various concentrations of MM in photobatch reactor. The estimated mass transfer coefficient was used to be 3.010^-5, 5.510^-5, 9.110^-5 m/s in PAC adsorption and 2.010^-5, 1.110^-5, 9.010^-6 m/s in TiO₂ adsorption for a different MM concentration of 20, 50 and 70 mg/L, respectively. Photocatalysis kinetics was same with TiO2 of 0.2 g/L regardless of TiO₂ amounts and the MM degradation kinetics was enhanced by TiO₂ catalysis rather than only UV light degradation. Among the photocatalysis kinetics model with first-order, second-order and Langmuir-Hinshelwood (L-H) model, a second-order kinetic model was found to well present the experimental data of MM by TiO₂ catalyst for the range of various TiO₂ amounts and MM concentration studied. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Adsorbent, Adsorption, Adsorption Isotherm, Adsorption Isotherms, Adsorption Kinetics, Carbon, Degradation, Freundlich Isotherm, Herbicide, Isotherm, Isotherms, Kinetic, Kinetics, Langmuir, Langmuir Isotherm, Mass Transfer, Metsulfuron Methyl, Metsulfuron-Methyl, Photocatalysis, Powdered Activated Carbon, Removal, Titanium Oxide, Transfer Coefficient, Water

? Wang, S.B., Terdkiatburana, T. and Tadé, M.O. (2008), Single and co-adsorption of heavy metals and humic acid on fly ash. Separation and Purification Technology, 58 (3), 353-358.

Full Text: 2008\Sep Pur Tec58, 353.pdf

Abstract: Heavy metals and humic acid are two important pollutants in surface and waste water systems. In this study, fly ash, an industrial waste, is used as a low-cost adsorbent for simultaneous removal of heavy metals and humic acid. The investigations were conducted for individual pollutant adsorption along with co-adsorption of both pollutants. It is found that, for single pollutant system, fly ash can achieve adsorption of lead ion at 18 mg/g, copper ion at 7 mg/g and humic acid at 36 mg/g, respectively. For co-adsorption, complexation of heavy metals and humic acid plays an important role. The presence of humic acid in water will provide additional binding sites for heavy metals, thus promoting metal adsorption on fly ash. For Pb-HA and Cu-HA systems, Pb²⁺ and Cu²⁺ adsorption can increase to 37 and 28 mg/g, respectively, at pH 5 and 30°C. However, the heavy metal ions present in the system will compete with the adsorption of humic acid on fly ash, thus resulting in a decrease in humic acid adsorption. For all cases, dynamic adsorption can be described by the first-order and second-order kinetics. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Adsorbent, Adsorbents, Adsorption, Co-Adsorption, Complexation, Copper, Fly Ash, Fulvic-Acid, Heavy Metal, Heavy Metal Ions, Heavy Metals, Humic Acid, Immobilization, Kinetics, Lead, Metal, Metal Adsorption, Metal Ions, Metals, pH, Removal, Sorption, Ultrafiltration, Waste Water, Water

? Lei, L.C., Li, X.J. and Zhang, X.W. (2008), Ammonium removal from aqueous solutions using microwave-treated natural Chinese zeolite. Separation and Purification Technology, 58 (3), 359-366.

Full Text: 2008\Sep Pur Tec58, 359.pdf

Abstract: In this study, natural Chinese zeolite pretreated by sodium chloride solution under microwave irradiation was used to remove ammonium from aqueous solution. Adsorption kinetics, adsorption equilibrium isotherms and the effect of the individual presence of other cations and humic acid on the removal of ammonium were investigated by conducting a series of batch experiments. The zeolite treated under microwave irradiation had the highest ammonium adsorption capacity value, followed by the zeolite obtained by thermal process and the untreated zeolite. The kinetic studies confirmed that the adsorption of ammonium on the zeolite treated under microwave irradiation could be described by the pseudo-second-order kinetic model, and intra-particle diffusion controlled the limiting rate of the adsorption process. Five isotherm models were used to describe the isotherm data. Three-parameter isotherm models (Redlich-Peterson and Langmuir-Freundlich) provided much better isotherm data fitting than two-parameter isotherm models (Freundlich, Temkin and Langmuir). The presence of Na⁺, K⁺, Ca²⁺ and Mg²⁺ could reduce the uptake of ammonium onto the zeolite treated under microwave irradiation and the order of ammonium ion over other cations was Na⁺ > K⁺ > Ca²⁺ > Mg²⁺, while the presence of humic acid increased the uptake of ammonium. Due to their low cost, high adsorption capacity and selectivity, the zeolite treated under microwave irradiation has the potential to be utilized for cost-effective removal of ammonium from wastewater. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Adsorption, Adsorption Equilibrium, Ammonium Removal, Aqueous Solution, Aqueous Solutions, Chloride, Diffusion, Equilibrium, Humic Acid, Intra-Particle Diffusion, Ion-Exchange, Isotherm, Isotherms, Kinetic, Kinetics, Langmuir, Microwave, Recovery, Removal, Solution, Sorption, Transcarpathian Clinoptilolite, Waste-Water, Wastewater, Zeolite

? Huang, W.J. and Cheng, Y.L. (2008), Effect of characteristics of activated carbon on removal of bromate. Separation and Purification Technology, 59 (1), 101-107.

Full Text: 2008\Sep Pur Tec59, 101.pdf

Abstract: This study evaluates how the characteristics of activated carbon (AC) influence the adsorption-reduction of bromate (BrO₃^-) by performing kinetic and isotherm tests. Experimental results reveal that both physical and chemical effects simultaneously affect the adsorption-reduction process. The wood-based carbons contained more mesopores than coconut- and coal-based carbons, resulting in the adsorption of more BrO₃^-. The equilibrium- and maximum-adsorption capacities were calculated as a function of the effect of mesopore volume. The carbon surface chemistry seems to be significant in the adsorption-reduction process. Activated carbons with high pH(zpc) values and many basic groups exhibit a neutral or positive charge under typical pH conditions, promoting BrO₃^- adsorption-reduction at the carbon surface. The kinetic data obtained from three forms of carbons have been analyzed using three kinetic models-pseudo-first-order, pseudo-second-order and intraparticle diffusion models. Among the kinetic models studied, the intraparticle diffusion was the best applicable model to describe the adsorption of BrO₃^- onto AC. (C) 2007 Elsevier B.V. All rights reserved.

Keywords: Acid, Activated Carbon, Adsorption, Adsorption Isotherm, Adsorption Kinetic, Bromate, Bromide-Containing Waters, Carbon, Chemistry, Diffusion, Equilibrium, Isotherm, Kinetic, Kinetic Models, Mesopore, Ozonation, pH, Pore Size, Potassium Bromate, Rats, Removal, Surface-Chemistry, Systems, Tumors

? Lyubchik, S.B., Lyubchik, A.I., Lygina, E.S., Lyubchik, S.I., Makarova, T.L., Vital, J., do Rego, A.M.B. and Fonseca, I.M. (2008), Simultaneous removal of 3d transition metals from multi-component solutions by activated carbons from co-mingled wastes. Separation and Purification Technology, 60 (3), 264-271.

Full Text: 2008\Sep Pur Tec60, 264.pdf

Abstract: The main purpose of the present work was to study the simultaneous removal of 3d transition metals from multi-component solutions by novel porous material obtained from carbon-containing liquid and solid waste. The activated carbon was prepared from co-mingled natural organic waste: 25% sunflower husks, 50% petroleum waste and 25% low-grade bituminous coal. The porous carbon material was obtained via stages of pre-oxidation with binary eutectic Na/K carbonates (in order to avoid melting and coke formation), followed by “step by step” carbonization at 100-400°C in an inert atmosphere and activation with steam at 850°C. The adsorption of the 3d transition metals: copper(II), cobalt(III), nickel(II), iron(III), and chromium(III), on novel activated carbons has been investigated using multi-component model solutions. Experiments have been carried out on the thermodynamics of the simultaneous adsorption of the 3d transition metals in a static mode. The total metal removal combines the process of metal hydroxide precipitation in the solution with the metal cation adsorption on negatively charged carbon surface in a single operation unit. The carbon/metals interaction at the surface of spent adsorbents is discussed. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: 3d Transition Metals, Activated Carbon, Activated Carbons, Activation, Adsorbents, Adsorption, Aqueous-Solutions, Atmosphere, Cadmium, Carbon, Carbonization, Cation, Chromium, Coal, Cobalt, Copper, Cr(III) Adsorption, Equilibrium, Heavy-Metals, Interaction, Ion Adsorption, Iron, Kinetics, Liquid, Metal, Metals, Mode, Model, Nickel, Operation, Organic, Organic Waste, Petroleum Waste, Porous Carbon, Precipitation, Purpose, Removal, Rights, Solid Waste, Solution, Solutions, Surface, Thermodynamics, Waste, Water, Work, X-Ray Photoelectron Spectroscopy, Zinc

? Taqvi, S.I.H., Hasany, S.M. and Bhanger, M.I. (2008), Zn(II) ions removal from aqueous solution by Karachi beach sand, a mixed crystal systems. Separation and Purification Technology, 61 (2), 153-160.

Full Text: 2008\Sep Pur Tec61, 153.pdf

Abstract: The aim of this research work is to investigate sorption characteristic of beach sand for the removal of Zn(II) ions from aqueous solutions. The sorption of Zn(II) ions by batch dynamic method is carried out using dilute solutions (10^-4 M) of nitric, hydrochloric and perchloric acids along with deionized water and from buffers of pH 2-10. Maximum sorption is noticed from deionized water (88.3%) using 30min shaking time. Two equations, i.e. Morris-Weber and Lagergren have been tested to track the kinetics of removal process. The Langmuir, Freundlich and Dubinin-Radushkevich (D-R) model are subjected to sorption data to estimate sorption capacity, intensity and energy. The thermodynamic parameters Delta H, Delta S and Delta G are evaluated. The influence of common ions on the sorption of Zn(II) ions is also examined. Some ions reduce the sorption while most of the ions tested have very little effect. It can be concluded that beach sand has potential to remove Zn(II) ions from aqueous solutions at very low concentrations and for the treatment of industrial effluent carrying Zn(II) ions. (c) 2007 Elsevier B. V . All rights reserved.

Keywords: Beach Sand, Zn(II) Ions, Sorption, Sorption Isotherms, Kinetics, Thermodynamics, Haro River Sand, Waste Material, Fly-Ash, Adsorption, Sorption, Zinc

? Liu, Y. and Liu, Y. (2008), Biosorption isotherms, kinetics and thermodynamics. Separation and Purification Technology, 61 (3), 229-242.

Full Text: 2008\Sep Pur Tec61, 229.pdf

Abstract: Biosorption, as a cost-effective technology for the removal of soluble heavy metals and organics from aqueous solutions, has been extensively studied, and most biosorption research mainly focused on the process isotherms, kinetics and thermodynamics. Thus, this paper attempted to offer a better understating of representative biosorption isotherms, kinetics and thermodynamics with special focuses on theoretical approaches for derivation of combined Langmuir-Freundlich isotherm as well as the pseudo-first- and second-order kinetic equations and general rate law equation for biosorption. Meanwhile, some potential problems encountered in biosorption research were also discussed. (C) 2007 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Aerobic Granular Sludge, Aqueous Solutions, Aqueous-Solutions, Biosorption, Biosorption Isotherms, Cephalosporium-Aphidicola, Elovich Equation, Equilibrium, Heavy Metals, Heavy-Metals, Isotherm, Isotherms, Kinetic, Kinetic Equations, Kinetics, Kinetics and Thermodynamics, Langmuir-Freundlich, Langmuir-Freundlich Isotherm, Law, Metals, Nickel(II) Ions, Potential, Rate Law, Removal, Research, Rhizopus-Arrhizus, Rights, Second Order, Second-Order, Solute Adsorption, Technology, Thermodynamics, Waste Biomass

? Atia, A.A., Donia, A.M. and Yousif, A.M. (2008), Removal of some hazardous heavy metals from aqueous solution using magnetic chelating resin with iminodiacetate functionality. Separation and Purification Technology, 61 (3), 348-357.

Full Text: 2008\Sep Pur Tec61, 348.pdf

Abstract: A magnetic chelating resin with iminodiacetate functionality was prepared and investigated. This resin showed a powerful uptake behavior towards Pb(II), Cd(II), Zn(II), Ca(II) and Mg(II). Kinetic and thermodynamic characteristics of uptake process were evaluated. The uptake values obtained are comparable to that of commercial resin with the same functionality (Lewatit TP-207) but with faster kinetics. A correlation was found between the affinity of the resin towards the investigated metal ions and the values of stability constants of their complex formation. The regeneration of the resin was carried out using 0.2 M EDTA with efficiency over 96%. Recovery of Pb(II) (as an example) from aqueous solutions using column technique was carried out. The total adsorption capacity (N-o) value obtained from bed depth service time (BDST) model was found to be comparable with the experimental value of q(s). The values of critical bed height (Z(o)) and rate constant of adsorption (K-a) were found to be 0.583 cm and 41.9 L/(mol min). (C) 2007 Published by Elsevier B.V.

Keywords: Iminodiacetate Resin, Magnetic Resins, Thermodynamics, Kinetics, Regeneration, Ion-Exchange-Resins, Glycidyl Methacrylate, Selective Separation, Uptake Behavior, Adsorption, Amine, Chitosan, Equilibrium, Copper(II), Mercaptan

? Azizian, S. (2008), Comments on “Biosorption isotherms, kinetics and thermodynamics” review. Separation and Purification Technology, 63 (2), 249-250.

Full Text: 2008\Sep Pur Tec63, 249.pdf

Keywords: Solid/Solution Interfaces, Solute Adsorption, Models, Sorption, Ions

? Araneda, C., Fonseca, C., Sapag, J., Basualto, C., Yazdani-Pedram, M., Kondo, K., Kamio, E. and Valenzuela, F. (2008), Removal of metal ions from aqueous solutions by sorption onto microcapsules prepared by copolymerization of ethylene glycol dimethacrylate with styrene. Separation and Purification Technology, 63 (3), 517-523.

Full Text: 2008\Sep Pur Tec63, 517.pdf

Abstract: The removal of Cd(II) and Cu(II) ions from aqueous solutions was studied by sorption onto microcapsules prepared by copolymerizing ethylene glycol dimethacrylate (EGDMA) and styrene (ST). The microcapsules were prepared by an in situ radical polymerization method by adding the extractant compound, 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester, and the monomers to the continuous aqueous phase. The extractant was immobilized within the microcapsules (MCs) which presented a spherical shape with rough surface. High productions of MCs with an important retention of extractant were achieved. Microcapsules constituted by a copolymer of 65% EGDMA and 35% ST presented best capacity of sorption of both metals. These MCs presented sufficient degree of cross-linking and a suitable balance of hydrophilic-hydrophobic character. The experimental data from chemisorption of metals onto the microcapsules fitted well the applied pseudo-second-order kinetics model. The alkylphosphonic extractant presented a higher rate constant and a higher equilibrium sorption capacity for Cd(II) than for Cu(II) at the pH used in this study.

Keywords: Adsorption, Alkylphosphonic Extractant, Aqueous Phase, Aqueous Solutions, Capacity, Cd(II), Chemisorption, Copolymer, Copolymerization, Crosslinking, Cu(II), Cu(II) Ions, Data, Equilibrium, Ethylene Glycol, Experimental, Immobilized, in Situ, Kinetics, Kinetics Model, Metal, Metal Ions, Metals, Microcapsules, Model, pH, Polymerization, Pseudo Second Order, Pseudo Second Order Kinetics, Pseudo-Second-Order, Pseudo-Second-Order Kinetics, Rate Constant, Removal, Retention, Solutions, Sorption, Sorption Capacity, Styrene, Surface, Wastewater Treatment

? Balaria, A. and Schiewer, S. (2008), Assessment of biosorption mechanism for Pb binding by citrus pectin. Separation and Purification Technology, 63 (3), 577-581.

Full Text: 2008\Sep Pur Tec63, 577.pdf

Abstract: Bio sorption of lead (Pb) from aqueous solution using citrus peels can provide an efficient and cost-effective solution for lead removal from industrial wastewaters. These peels contain the biopolymer pectin that has a strong affinity for metal ions. A better understanding of the chemistry behind these interactions can help in the preparation of commercial biosorbents using waste citrus peels. This study was conducted in order to obtain mechanistic information about Pb binding by low and highly methoxylated citrus pectins. Potentiometric titrations revealed that carboxyl groups are important contributors to negative charge of these biopolymers, which was further confirmed by a pH variability study. Pb binding by both low- and high-methoxylated pectins follows second-order kinetics, suggesting that each divalent metal ion binds to two monoprotic functional groups. Fourier transform infrared (FTIR) spectrometric results confirm that carboxylic acid groups are active participants in Pb binding by citrus pectin. (c) 2008 Elsevier B.V. All rights reserved.

Keywords: Aqueous Solution, Binding, Bio-Sorption, Biopolymers, Biosorbents, Biosorption, Biosorption Mechanism, Carboxylic, Charge, Chemistry, Citrus Pectin, Citrus Peels, Cost-Effective, Divalent Metal-Ions, Esterification, FTIR, FTIR Spectrometry, Functional Groups, Heavy-Metals, Hg²⁺ Adsorption, Information, Infrared, Ions, Kinetics, Lead, Lead Removal, Mechanism, Metal, Metal Ions, Nov, Orange, Pb, Pectin, Peels, pH, Potentiometric Titration, Preparation, Removal, Rights, Second Order, Second Order Kinetics, Second-Order, Second-Order Kinetics, Solution, Sorption, Transform Infrared-Spectroscopy, Understanding, Variability, Waste, Wastewaters, Water

? Chen, S.L., Xu, Z.P., Zhang, Q., Lu, G.Q.M., Hao, Z.P. and Liu, S.M. (2009), Studies on adsorption of phenol and 4-nitrophenol on MgAl-mixed oxide derived from MgAl-layered double hydroxide. Separation and Purification Technology, 67 (2), 194-200.

Full Text: 2009\Sep Pur Tec67, 194.pdf

Abstract: In this research, the removal of two phenols (4-nitrophenol and phenol) from aqueous solution was investigated using MgAl-mixed oxide. This oxide was prepared by calcining crystalline MgAl-CO₃-layered double hydroxide (LDH) at 500°C for 4 h. we found that it takes 10-12 h for adsorption of 4-nitrophenol to reach the equilibrium at room temperature while the equilibrium time is 20-25 h for phenol adsorption. The kinetic process of 4-nitrophenol adsorption seemingly follows the first-order reaction but phenol is adsorbed in a pseudo-second-order model. We also noted that the maximum adsorption amount of 4-nitrophenol by fitted three-parameter Langmuir-Freundlich isotherm is 367.8 mg/g, much higher than that of phenol (46.9 mg/g). The differences in the adsorption kinetics and dynamics have been related to the adsorption mechanism and adsorbate-adsorbent interactions. The reconstruction of MgAl-mixed oxide in aqueous solution incorporates 4-nitrophenolate into the interlayer. However, it is difficult to intercalate phenolate due to its weaker affinity for LDH in comparison with OH^-. In addition, adsorption of MgAl-mixed oxide for 4-nitrophenol and phenol is slightly affected by the initial pH, but considerably facilitated by increasing the adsorption temperature. (c) 2009 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Adsorption Kinetics, Aqueous-Solutions, Delivery, Hydrotalcite-Like Compounds, Isotherm, Kinetics, Layered Double Hydroxide (LDH), Oxidation, pH, Phenols, Pollutants, Product, Reconstruction, Removal, Water

? Singh, V., Pandey, S., Singh, S.K. and Sanghi, R. (2009), Removal of cadmium from aqueous solutions by adsorption using poly(acrylamide) modified guar gum-silica nanocomposites. Separation and Purification Technology, 67 (3), 251-261.

Full Text: 2009\Sep Pur Tec67, 251.pdf

Abstract: Novel nanocomposite adsorbent materials were synthesized by dehydroxylation condensation of tetraethoxy silane (TEOS) in the presence of guar gum-graft-poly(acrylamide) using ammonium hydroxide as catalyst and ethanol as co-solvent. The ratio of H₂O:TEOS:EtOH was varied at fixed concentration of copolymer and catalyst to obtain a series of materials which were evaluated for their ability to bind cadmium from the aqueous solution in a preliminary investigation. The most efficient adsorbent material thus obtained was calcinated (in air) in stages up to 1100C where the binding ability of the material could be further tailored and materials of different performances were obtained. The material calcined at 600C was found most efficient and its adsorbent behavior was studied in detail taking Cd(II) as representative ion. The chemical, structural and textural characteristics of the material were determined by FTIR, XRD, TGA-DTA, PL, SEM and EDAX analysis. BET (Brunauer-Emmett-Teller) specific surface area and pore structure of the adsorbent was also examined. The adsorption behavior of the bioadsorbent was investigated by performing both kinetics and equilibrium studies in batch conditions. The adsorption conditions for the adsorbent were optimized by varying several experimental parameters i.e. contact time, initial cadmium concentration, temperature, adsorbent dose, electrolyte amount and pH of the solution. The adsorption showed pseudo-second-order kinetics with a rate constant of 2.8510^-3, 1.8810^-4 and 2.0510^-4 g mg^-1 min^-1 at 500,700 and 900 mg L^-1 initial Cd(II) concentrations, respectively. The adsorption data were modeled using both the Langmuir and Freundlich isotherms. The data fitted better to Langmuir isotherm indicating unilayer adsorption. The maximum adsorption capacity (q_max) for the composite was found to be significantly very high (2000 mg g^-1). The thermodynamic study revealed the endothermic and spontaneous nature of the sorption. The composite exhibited very high reusability for more than six cycles. Thereafter its efficiency slowly declined and reached 56% by the 10th cycle. The porous composite sorbent was easy to prepare and was also found to be highly stable and photoluminescent making this biosorption approach quite attractive from the industrial point of view. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Adsorbent, Adsorbent Dose, Adsorption, Adsorption Behavior, Adsorption Capacity, Air, Ammonium, Amorphous Silica, Analysis, Approach, Aqueous Solution, Aqueous Solutions, Batch, Behavior, Bet, Binding, Biosorption, Cadmium, Calcined, Capacity, Catalyst, Cd(II), Cd(II) Adsorption, Characteristics, Chemical, Coir Pith, Composite, Concentration, Copolymer, Data, Dehydroxylation, EDAX, Efficiency, Endothermic, Equilibrium, Equilibrium Studies, Ethanol, Experimental, Freundlich, FTIR, Guar-Graft-Poly(Acrylamide)-Silica, Heavy-Metal Ions, Investigation, Isotherm, Isotherms, Kinetics, L1, Langmuir, Langmuir And Freundlich Isotherms, Langmuir Isotherm, Modified, Nanocomposite, Nanocomposites, pH, Photoluminescence, Polyacrylamide, Porous Silicon, Pseudo Second Order, Pseudo Second Order Kinetics, Pseudo-Second-Order, Pseudo-Second-Order Kinetics, Rate Constant, Removal, Rights, Saw Dust, SEM, Solution, Solutions, Sorbent, Sorption, Specific Surface, Specific Surface Area, Structure, Surface, Surface Area, Temperature, TEOS, Thermodynamic, Thermodynamics, Water, XRD

? Hsieh, C.T., Fan, W.S., Chen, W.Y. and Lin, J.Y. (2009), Adsorption and visible-light-derived photocatalytic kinetics of organic dye on Co-doped titania nanotubes prepared by hydrothermal synthesis. Separation and Purification Technology, 67 (3), 312-318.

Full Text: 2009\Sep Pur Tec67, 312.pdf

Abstract: A hydrothermal treatment combined with metal doping was employed to prepare highly porous Co-doped TiO₂ nanotubes (TNTs) for enhancement of adsorption and visible-light-driven photocatalysis capabilities of basic violet 10 (BV10) from liquid phase. The specific surface area of prepared TNTs can reach the maximal value of similar to 379 m²/g. These tubes are hollow scrolls with a typical outer diameter of about 10-15 nm, inner diameter 5-10 nm and length of several micrometers. The anatase-type of TNTs has an average Co-dopant concentration of 510²⁰ ions/cm³, determined by an electron dispersive X-ray spectrometer. The adsorptive surface coverage on TNTs was found to be ca. 7.61-7.63%, showing a low affinity between BV10 molecules and TNTs. A pseudo-second-order reaction model was used to fit with the experimental data of adsorption and photocatalystic kinetic curves. The adsorption rate constant has one order higher than the photocatalytic rate constant, reflecting that the photocatalysis of the basic dye is the rate-determining step during the adsorption/photocatalysis process. These novel Co-doped TNTs are believed to be a promising candidate in a variety of photocatalysis applications because of the combination effect of a high porosity with a photocatalysis under visible illumination. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Adsorption Rate, Basic Dye, Basic-Dyes, Carbons, Cobalt Doping, Combination Effect, Concentration, Coverage, Data, Degradation, Dye, Experimental, Hydrothermal Synthesis, Hydrothermal Treatment, Ion-Implantation, Kinetic, Kinetics, Length, Liquid, MCM-41, Metal, Model, Nanoparticles, Nanotubes, Organic, Photocatalysis, Photocatalytic, Porosity, Pseudo Second Order, Pseudo-Second-Order, Rate Constant, Rate-Determining Step, Removal, Rights, Solar-Cells, Specific Surface, Specific Surface Area, Surface, Surface Area, Synthesis, TiO₂, TiO₂ Nanotubes, Titania Nanotubes, Treatment, Value, Visible-Light Photocatalysis,Adsorption, Waste-Water, X-Ray

? Alemayehu, E., Thiele-Bruhn, S. and Lennartz, B. (2011), Adsorption behaviour of Cr(VI) onto macro and micro-vesicular volcanic rocks from water. Separation and Purification Technology, 78 (1), 55-61.

Full Text: 2011\Sep Pur Tec78, 55.pdf

Abstract: Adsorption by volcanic rocks is investigated as a possible alternative to the conventional method of Cr(VI) removal from polluted waters. In this work, adsorption of Cr(VI) onto pumice (VPum) and scoria (VSco) has been studied by using a batch method at room temperature. The following factors affecting sorption of Cr(VI) were investigated: solution pH, contact time, type and size of adsorbents, adsorbent dose and initial metal ion concentration. The maximum adsorption yield, 77% for VSco and 80% for VPum, was obtained at low pH of about 2. The applicability of the Langmuir as well as Freundlich adsorption isotherms for the present system is tested. The batch sorption kinetics has been mathematically described using the Lagergren pseudo-first order, pseudo-second order equations and equations for intra-particle and liquid film diffusion. For both VPum and VSco, the entire kinetic data fitted well with pseudo-second-order reaction rate model. In the case of VSco, the rate constant was the highest (338×10^-3 kg mg^-1 h^-1) and the VPum gave the lowest (7×10^-3 kg mg^-1 h^-1). The experimental results inferred that electrostatic attraction and surface complexation are the major adsorption mechanisms for binding Cr(VI) ions to the macro and micro-vesicular volcanic rocks. The two volcanic rocks tested have potential for an inexpensive and suitable method for removal of Cr(VI) from polluted waters. (c) 2011 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Aqueous-Solution, Cr(VI), Cr(VI) Removal, Ethiopia, Freundlich, Heavy-Metals, Hexavalent Chromium, Isotherms, Kinetic, Kinetics, Langmuir, Low-Cost Adsorbents, pH, Pumice, Pumice, Removal, Scoria, Sorption, Trace-Metals, Waste-Water

? Zhou, Y.B., Chen, L., Lu, P., Tang, X.Y. and Lu, J. (2011), Removal of bisphenol A from aqueous solution using modified fibric peat as a novel biosorbent. Separation and Purification Technology, 81 (2), 184-190.

Full Text: 2011\Sep Pur Tec81, 184.pdf

Abstract: Fibric peat was modified with hexadecyltrimethylammonium bromide (HTAB) and its efficiency as a biosorbent for the removal of endocrine disrupting chemical-bisphenol A (BPA) was investigated. The HTAB-modified peat displayed a faster initial BPA sorption and substantially higher capacity than the unmodified peat over a wide concentration range. Kinetic study showed that the sorption followed the pseudo-second-order kinetic model. The maximum sorption capacity of 31.40 mg g^-1 was obtained at initial concentration of 45 mg L^-1. The BPA sorption to HTAB-modified peat was better described by Freundlich isotherm, while Langmuir isotherm fits better to the BPA sorption against unmodified peat. Comparing with raw fibric peat, the HTAB-modified peat removed more BPA molecules and the desorption rate was much lower. It shows that the improved hydrophobic interactions are the dominant mechanism and the chemical modification of the peat surface greatly enhanced the sorption capacity toward organic compound dissolved in water. (C) 2011 Elsevier B.V. All rights reserved.

Keywords: Activated-Sludge, Adsorbents, Adsorption, Bisphenol A, Drinking-Water, Dye Removal, Isotherm, Kinetic, Langmuir, Liquid-Chromatography, Membrane, Modification, Nonylphenol, Peat, Quaternary Ammonium, Removal, Sorption, Waste-Water, Water Treatment

? Thanh, D.N., Singh, M., Ulbrich, P., Strnadova, N. and Štěpánek, F. (2011), Perlite incorporating gamma-Fe₂O₃ and alpha-MnO₂ nanomaterials: Preparation and evaluation of a new adsorbent for As(V) removal. Separation and Purification Technology, 82, 93-101.

Full Text: 2011\Sep Pur Tec82, 93.pdf

Abstract: Novel composite adsorbents for As(V) removal from aqueous solution were synthesized by successfully incorporating α-MnO₂ nanorods and γ-Fe₂O₃ nanoparticles onto ball-milled expanded perlite carrier material. The composite adsorbents were characterized using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Powder X-ray diffraction (XRD) and Brunauer-Elmet-Teller nitrogen adsorption (BET-N₂ adsorption). The BET surface area of ball-milled expanded perlite increased by 4.0 and 7.1 times after the incorporation of γ-Fe₂O₃ and alpha-MnO₂ nanomaterials. The adsorption capacity for As(V) was found to be highly pH dependent and the adsorption kinetics followed the pseudo-second-order kinetic model. The Langmuir isotherm was found to be the best model to describe the adsorption of As(V) on both composites and the adsorption capacity was 4.64 and 7.09 mg g^-1 for γ-Fe₂O₃ and α-MnO₂ containing adsorbents as compared to 0.0025 mg g^-1 for perlite alone, confirming that these composites retain the constituent nanomaterial properties while being macroscopic particles suitable for arsenic removal in water treatment technology. (C) 2011 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Adsorption, α-MnO₂ Nanorods, Aqueous-Solution, Arsenate Adsorption, Arsenic Removal, Ball-Milling, BET, Expanded Perlite, γ-Fe₂O₃ Nanoparticles, Ions, Isotherm, Kinetics, Langmuir, Manganese, Nanoparticles, Perlite, pH, Preparation, Sorption, Water, Water Treatment

? Sun, Y.B., Yang, S.T., Sheng, G.D., Guo, Z.Q., Tan, X.L., Xu, J.Z. and Wang, X.K. (2011), Comparison of U(VI) removal from contaminated groundwater by nanoporous alumina and non-nanoporous alumina. Separation and Purification Technology, 83, 196-203.

Full Text: 2011\Sep Pur Tec83, 196.pdf

Abstract: In this study, the sorption and desorption of U(VI) from contaminated groundwater by nanoporous and non-nanoporous alumina were investigated under ambient conditions. The nanoporous and non-nanoporous alumina were characterized by XRD, specific surface area analysis, TEM and potentiometric acid-base titration. The nanoporous alumina exhibited high sorption capacity, large specific surface area, high surface acidity constants, low difference of surface acidity constants and high pH(PNZC) (point of net zero charge) due to the nanoporous effect. The worm-like shape nanoporous alumina was transferred into the floc-like shape gibbsite after the sorption in terms of TEM images. Sorption kinetics and sorption isotherms of U(VI) on both nanoporous and non-nanoporous alumina can be interpreted by pseudo-second order kinetic model and the Langmuir model, respectively. The sorption of U(VI) on nanoporous alumina is strongly dependent on pH and independent of ionic strength, whereas U(VI) sorption on non-nanoporous alumina is dependent on pH and ionic strength. The sorption mechanism is assumed to be mainly inner-sphere surface complexation for nanoporous alumina and outer-sphere surface complexation for non-nanoporous alumina. Approximately 100% of U(VI) was desorbed from non-nanoporous alumina while only similar to 5% of U(VI) was extracted from nanoporous alumina when the concentration of NaHCO₃ was increased to 0.01 M in terms of sequential desorption experiments. The nanoporous alumina can be used as an efficient material for in situ immobilization of U(VI) from contaminated groundwater. (C) 2011 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Aqueous-Solutions, Drinking-Water, Equilibria, Groundwater, Hematite, Kinetic, Kinetics, Langmuir, Microbial Reduction, Nanoporous Alumina, pH, Removal, Site-Binding Model, Sorption, Sorption Kinetics, Transitions, U(VI), Uranium, Water Interface