Personal Research Database

Full Text: 2007\Sep Pur Tec54, 187.pdf

Abstract: This study was to investigate the adsorption characteristics of Cu(II) onto spent activated clay (SAC) or so-called spent bleaching earth, a waste produced from an edible oil refinery company. Results of kinetic experiments showed that the Cu(II) adsorption rate was fast and more than 90% of Cu adsorption occurred within 5 min. Among the kinetic models tested, the adsorption kinetics was best described by the pseudo-second-order equation. The rate of adsorption decreased with increasing surface loadings. Results of equilibrium experiments showed that the solution pH was the key parameter affecting the adsorption characteristics. The adsorption of Cu(II) ions onto SAC occurs up to the precipitation pH, and then the precipitation of Cu ions starts. The Langmuir adsorption isotherm properly describes the equilibrium adsorption and the maximum adsorption capacities of SAC towards Cu(II) were determined to be 10.9, 11.5, and 13.2 mg/g, respectively at pH 5.0, 5.5, and 6.0. As temperature was increased from 4 to 50°C, the adsorption capacity increased from 9.5 to 12.8 mg/g for solution pH of 5.0. Values of G° ranging from -5.73 to -7.26 kcal/mol suggest that the adsorption process is spontaneous and mainly governed by specific surface interaction mechanism. The values of H° and S° were 3.47 kcal/mol and 33.2 cal/(mol K), respectively. Results of this study will be useful for future scale up for using this material as a low-cost adsorbent for the removal of Cu(II) from wastewater. (c) 2006 Elsevier B.V. All rights reserved.

Keywords: Activated Clay, Adsorbent, Adsorption, Adsorption Capacities, Adsorption Capacity, Adsorption Copper, Adsorption Isotherm, Adsorption Kinetics, Adsorption Process, Adsorption Rate, Bleaching Earth, Capacity, Characteristics, Clay, Copper(II), Cu, Cu(II), Cu(II) Ions, Dilute Aqueous-Solution, Equilibrium, Experiments, Fly-Ash, Interaction, Ions, Isotherm, Kinetic, Kinetic Models, Kinetics, Langmuir, Langmuir Adsorption Isotherm, Loadings, Low Cost, Low Cost Adsorbent, Low-Cost Adsorbent, Mechanism, Metal-Ions, Methylene-Blue, Models, pH, Physicochemical Environment, Precipitation, Pseudo Second Order, Pseudo-Second-Order, Pseudo-Second-Order Equation, Removal, Rights, Scale, Sludge-Ash, Solution, Specific Surface, Spent Activated Clay, Spontaneous, Surface, Surface Interaction, Temperature, Thermodynamics, Waste, Waste-Water, Wastewater

? Rakotondramasy-Rabesiaka, L., Havet, J.L., Porte, C. and Fauduet, H. (2007), Solid–liquid extraction of protopine from Fumaria officinalis L.—Analysis determination, kinetic reaction and model building. Separation and Purification Technology, 54 (2), 253-261.

Full Text: 2007\Sep Pur Tec54, 253.pdf

Abstract: Solid–liquid extraction was performed in a batch extractor, from aerial parts of Fumaria officinalis, in order to obtain an extract containing protopine. This study relates the influences of the temperature and nature of the solvent on the kinetics and rates of extraction. A method to quantify the protopine contents by Reverse Phase-High Pressure Liquid Chromatography was initially perfected. Then, a batch-extraction model based on the assumption of a second-order mechanism was developed to predict the rate constant of extraction, the saturated extraction capacity and the initial extraction rate with various temperatures in two solvents, water and ethanol 44% (w/w) in water. Furthermore, the activation energies were determined as based on the second-order rate constants of extraction used for the model building. The values resulting from these calculations and experiments were compared and discussed.

Keywords: Solid–Liquid Extraction, Fumaria, Kinetics, Protopine, Batch Experiment

? Yue, Q.Y., Li, Q., Gao, B.Y. and Wang, Y. (2007), Kinetics of adsorption of disperse dyes by polyepicholorohydrin-dimethylamine cationic polymer/bentonite. Separation and Purification Technology, 54 (3), 279-290.

Full Text: 2007\Sep Pur Tec54, 279.pdf

Abstract: The characterization of polyepicholorohydrin-dimethylaminelbentonite and the kinetics of adsorption of four disperse dyes, namely, Disperse Yellow Brown S-2RFL (DYB S-2RFL), Disperse Red S-R (DR S-R), Disperse Blue SBL (DB SBL) and Disperse Yellow (DY SE-6GFL) onto organophilic bentonite (polyepicholorohydrin-dimethylamineibentonite) have been studied at various solution concentrations and temperatures. The adsorption kinetics was studied in terms of a two-step first-order kinetic rate equation and intra-particle diffusion model. The adsorption process has been found to follow with two different rate constants (k(1) and k(2)) for two-step first-order kinetic rate equation and also two different intra-particle diffusion rate constants (k(int1) and k(int2)) for intra-particle diffusion model. For both the kinetic steps, the energies of activation of adsorption (E-a1 and E-a2) and other thermodynamic parameters (Delta H-1* and Delta H-2*, Delta S-1* and Delta S-2*, Delta G(1)* and Delta G(2)*) have been calculated using Arrhenius’s and Eyring’s equation, respectively. It has been found that or both the adsorption kinetic steps, E-a1 and E-a2 are corresponding to the values of k(1) and k(2) and Delta H-1* < -T-av Delta S-1*, Delta H-2* < -T-av Delta S-2* and Delta G* > 0, which means that the influence of entropy is more remarkable than enthalpy in activation reaction and the adsorption process is not spontaneous. (c) 2006 Elsevier B.V. All rights reserved.

Keywords: EPI-DMA/Bentonite, Disperse Dyes, Adsorption Kinetics, Rate Constants, Thermodynamic Parameters, Aqueous-Solutions, Organic-Compounds, Activated Carbon, Sorption, Organoclays, Water, Acid, Acid-Blue-193, Bentonite, Biosorbent

? Malkoc, E. and Nuhoglu, Y. (2007), Potential of tea factory waste for chromium(VI) removal from aqueous solutions: Thermodynamic and kinetic studies. Separation and Purification Technology, 54 (3), 291-298.

Full Text: 2007\Sep Pur Tec54, 291.pdf

Abstract: The objective of this study is to assess the uptake of hexavalent chromium Cr(VI) from aqueous solutions onto tea factory waste (TFW). The study also investigates the effects of process parameters such as pH, initial concentration of Cr(VI) ion, temperature, agitating rate and adsorbent mass. The nature of the possible adsorbent and metal ion interactions was examined by the FTIR technique. Zeta potential values of the TFW were defined at different values of pH according to deionized water. The maximum adsorption is noted at pH 2.0. The adsorption data follow the Langmuir model better than the Freundlich model and the adsorption equilibrium was described well by the Langmuir isotherm model with maximum adsorption capacity of 54.65 mg g⁻¹ of Cr(VI) ions on TFW at 60 °C. Adsorption capacity increased from 30.00 to 39.62 mg g⁻¹ with an increase in temperature from 25 to 60 °C at 400 mg L⁻¹ of initial Cr(VI) ion concentration. The adsorption of Cr(VI) ions increased with increasing temperature indicating endothermic nature of the adsorption process. Using the first-order kinetic constants, the activation energy of adsorption (E_a) was determined as 18.57 kJ mol⁻¹ according to the Arrhenius equation. The present investigation aimed the heavy metal adsorption from synthetic wastewaters with another pollutant matter. This study indicated that the TFW can be used as an effective and environmentally friendly biosorbent for the treatment of Cr(VI) containing aqueous solutions. Various thermodynamic parameters, such as ΔG°, ΔH° and ΔS° have been calculated. The thermodynamics of Cr(VI) ion onto TFW system indicates spontaneous and endothermic nature of the process.

Keywords: Adsorption, Chromium(VI), Isotherms, Tea Factory Waste, Kinetics, Thermodynamic Parameters

? Chung, M.K., Tsui, M.T.K., Cheung, K.C., Tam, N.F.Y. and Wong, M.H. (2007), Removal of aqueous phenanthrene by brown seaweed Sargassum hemiphyllum: Sorption-kinetic and equilibrium studies. Separation and Purification Technology, 54 (3), 355-362.

Full Text: 2007\Sep Pur Tec54, 355.pdf

Abstract: The batch sorption-kinetics and equilibrium uptake of phenanthrene (PHE), a hydrophobic organic compound (HOC), in aqueous compartment were investigated using dead tissue of brown seaweed Sargassum hemiphyllum under various conditions for 24 h. It was found that the higher the shaking rates (50-250 rpm) and temperatures (15-35°C), the higher the sorption rates of PHE, but no significant changes were observed for the maximum sorption capacities. Study with different initial PHE concentrations (50-1000 mu g L^-1) showed that a higher ambient level of PHE resulted in a faster initial uptake rate and greater sorption capacity. The presence of ionic species (0.01-1 M NaCl) changed the sorption-kinetics of PHE markedly by altering the maximum removal of PHE, but not the initial sorption rates. No significant removal variations were noted under various initial pH (pH 2-11), while constant alkalinity resulted in an alleviated PHE sorption by Sargassum. The sorption- kinetics of PHE typically followed more closely to the pseudo- second-order model (r² > 0.85) than pseudo-first-order equation (r² > 0.72). Removal capacities were in the range of 430-460 mu g g^-1 for tests spiked with 1000 mu g L^-1 PHE. Typical percentage removals of aqueous PHE by Sargassum for all the investigated factors (e.g. initial pH and ionic strength) were in the range of 91.7-98.4%. Log Sargassum-water and the organic carbon normalized partition coefficient were calculated as 3.83 and 3.96 mL g^-1, respectively. The present study provided valuable information for achieving optimal sorption of aqueous PHE using Sargassum as an effective sorbent for removing HOCs in wastewaters and urban runoffs. (c) 2006 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Alkalinity, Ambient, Biomass, Biosorption, Capacity, Carbon, Concentrations, Equilibrium, Heavy-Metals, Highway Runoff, HOCs, Hydrophobic, Information, Ionic Species, Ionic Strength, Kinetics, Macroalgae, Model, Organic, Organic Carbon, Organic Matter, Organic-Matter, Pahs, Partition, Partition Coefficient, pH, Phenanthrene, Pollutants, Polycyclic Aromatic-Hydrocarbons, Range, Removal, Sargassum, Seaweed, Sediments, Sorption, Sorption Capacity, Sorption Kinetics, Strength, Tests, Uptake, Urban, Waters

? Huang, Y.H., Hsueh, C.L., Huang, C.P., Su, L.C. and Chen, C.Y. (2007), Adsorption thermodynamic and kinetic studies of Pb(II) removal from water onto a versatile Al₂O₃-supported iron oxide. Separation and Purification Technology, 55 (1), 23-29.

Full Text: 2007\Sep Pur Tec55, 23.pdf

Abstract: The use of versatile sorbents has been investigated for wastewater treatment. An investigation into the use of activated alumina-supported iron oxide (denoted as FeAA), which is a by-product of the wastewater treatment plant. In our previous study, the FeAA has successfully been as heterogeneous photoassisted Fenton catalyst for degradation azo dye at neutral pH 7.0. In this work, the test and use of FeAA as adsorbent for the removal of lead (Pb²⁺) from water are carried out. The highest Pb²⁺ adsorption capacity was determined as 0.14 mmol g^-1 for 0.8 mmol dm^-3 initial Pb²⁺ concentration at pH 5.0 and 318 K. Adsorption data were well described by the Langmuir model and the thermodynamic constants of the adsorption process: ΔG°, ΔH° and ΔS° were evaluated as -19.4 kJ mol^-1 (at 318 K), 25.73 kJ mol^-1 and 0.113 J mmol^-1 K^-1, respectively. The pseudo-first-order and pseudo-second-order kinetic models were applied to test the experimental data. The pseudo-second-order kinetic model provided the best correlation of the experimental data compared to the pseudo-first-order model. © 2006 Elsevier B.V. All rights reserved.

Keywords: Adsorbent, Adsorption, Adsorption Capacity, Adsorption Process, Azo Dye, Capacity, Carbon, Catalyst, Catalytic-Oxidation, Concentration, Correlation, Degradation, Desorption, Dye, Equilibrium, Fenton, Fluidized-Bed Reactor, Goethite, Heavy-Metals, Heterogeneous, Investigation, Iron, Iron Oxide, Kinetic, Kinetic Model, Kinetic Models, Kinetic Studies, Langmuir, Langmuir Model, Lead, Lead, Mechanisms, Model, Models, Natural Organic-Matter, Pb(II), Pb²⁺, pH, Plant, Process, Pseudo Second Order, Pseudo-Second-Order, Removal, Sorbents, Test, Thermodynamic, Treatment, Wastewater, Wastewater Treatment, Wastewater Treatment Plant, Water

? Razah, M., Zhao, Y.Q. and Bruen, M. (2007), Effectiveness of a drinking-water treatment sludge in removing different phosphorus species from aqueous solution. Separation and Purification Technology, 55 (3), 300-306.

Full Text: 2007\Sep Pur Tec55, 300.pdf

Abstract: Drinking-water treatment sludge (DWTS) produced at water treatment plants is an inescapable byproduct and has long been treated as a waste for landfill. In this study, a series of batch adsorption tests were conducted using it wide range of phosphorus (P) species to determine the adsorption capacities of freshly dewatered aluminium salt based DWTS. The adsorption process is highly dependant on the pH of the suspension and is good at low pHs with adsorption capacities in the order of orthophosphate > polyphosphate > organic phosphate when these three P species were simulated according to their level in typical municipal wastewater. At pH 4.0, the adsorption capacity for orthophosphate was 10.2 Mg-PO43-/g DWTS, polyphosphate was 7.4 Mg-PO43-/g DWTS and organic phosphate was 4.8 Mg-PO43-/g DWTS. Subsequently, a continuous flow column test with dewatered Al-based DWTS as filter medium was conducted at a hydraulic loading of 2.79 m(1)/m(2) d and an extremely high P loading of 210.5 PO43-/m(2) d. The sludge bed remained stable and removed over 80% P in a 30 day period and the bed did not reach saturation point for over 60 days. This proves the potential of the sludge as a filter material in various forms of P immobilization, thus converting it from a waste to a useful material in pollutant control. (c) 2006 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Alummium, Drinking Water Treatment Sludge, Phosphorus Removal, Reuse, Treatment Works Sludge, Dewatered Alum Sludge, Waste-Water, Treatment Residuals, Competitive Adsorption, Phosphate Adsorption, Constructed Wetlands, Mechanisms, Retention, Capacity

? Ramesh, A., Hasegawa, H., Maki, T. and Ueda, K. (2007), Adsorption of inorganic and organic arsenic from aqueous solutions by polymeric Al/Fe modified montmorillonite. Separation and Purification Technology, 56 (1), 90-100.

Full Text: 2007\Sep Pur Tec56, 90.pdf

Abstract: Adsorption of arsenite [As(III)], arsenate [As(V)] and dimethylarsinate (DMA) from aqueous solutions onto polymeric Al/Fe modified montmorillonite was studied. Batch adsorption studies were carried out on the adsorption of As(III), As(V) and DMA as a function of contact time, pH, adsorbent dose and initial metal concentration. Fourier transform infrared spectrometry (FT-IR) and scanning electron microscopy (SEM) were used to analyze the functional groups and surface morphology of the montmorillonite or polymeric Al/Fe modified montmorillonite, respectively. SEM images show that modification with polymeric Al/Fe species reduces the clay particle size and aggregation. The results indicate that the maximum adsorption of polymeric Al/Fe modified montmorillonite was obtained in the pH range 3.0-6.0 for As(V), 7.0-9.0 for As(III) and 3.0-7.0 for DMA. The adsorption data was analyzed by both Freundlich and Langmuir isotherm models and the data was well fit by the Freundlich isotherm model. Kinetic data correlated well with the pseudo-second-order kinetic model, suggesting that the adsorption process might be chemical sorption. Thermodynamic studies showed that the adsorption process was endothermic and spontaneous in nature. The presence of phosphate and iron reduced the adsorption efficiency of arsenic, whereas other common coexisting ions had no significant effect on arsenic adsorption. The desorption studies were carried out using dilute NaCl solution. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Adsorbent, Adsorption, Adsorption Efficiency, Adsorption Process, Aggregation, Aqueous Solutions, Arsenate, Arsenic, Arsenic Adsorption, Arsenite, As(III), As(V), Blackfoot Disease, Chemical, Clay, Concentration, Contact Time, Desorption, Desorption Studies, Dimethylarsinic Acid, Dma, Drinking-Water, Efficiency, Electron Microscopy, Endothermic, Freundlich, Freundlich Isotherm, FT-IR, FTIR, Function, Functional, Functional Groups, Groundwater, Groups, Heavy-Metal Removal, Inorganic, Iron, Iron-Oxides, Isotherm, Isotherm Model, Isotherm Models, Isotherms, Kinetic, Kinetic Model, Kinetics, Langmuir, Langmuir Isotherm, Langmuir-Isotherm, Metal, Microscopy, Model, Models, Modification, Modified, Montmorillonite, Morphology, Nacl, Organic, Particle, Particle Size, pH, Phosphate, Polymeric, Polymeric Al, Fe, Polymeric Al, Fe Modified Montmorillonite, Polymeric Al, Fe Species, Process, Pseudo Second Order, Pseudo Second Order Kinetic, Pseudo-Second-Order, Pseudo-Second-Order Kinetic Model, Range, Scanning Electron Microscopy, Sem, Size, Solutions, Sorption, Species, Spectrometry, Spontaneous, Surface, Surface Morphology, Surfactant-Modified Montmorillonite, Titanium-Dioxide, Waste-Water

? Pimentel, P.M., González, G., Melo, M.F.A., Melo, D.M.A., Silva, Jr., C.N. and Assunção, A.L.C. (2007), Removal of lead ions from aqueous solution by retorted shale. Separation and Purification Technology, 56 (3), 348-353.

Full Text: 2007\Sep Pur Tec56, 348.pdf

Abstract: The equilibrium and kinetic properties of Pb²⁺ ion adsorption by retorted shale (RS) have been investigated during a series of batch adsorption experiments. The effects of pH, contact time and adsorbate initial concentration were evaluated. The pseudo-second-order model was used to predict the rate constants of adsorption system. Langmuir and Freundlich models were used to fit the equilibrium data, which showed that Langmuir best-fitted these data. Thermodynamic parameters of adsorption indicate spontaneous and endothermic nature of the process. (C) 2007 Elsevier B.V. All rights reserved.

Keywords: Adsorbent, Adsorption, Adsorption Isotherms, Aqueous Solution, Ash, Batch, Batch Adsorption, Clay, Concentration, Constants, Contact Time, Effects, Effects of pH, Endothermic, Equilibrium, Equilibrium Data, Freundlich, Heavy-Metals, Ion, Ion Adsorption, Kinetic, Kinetic Properties, Langmuir, Lead, Lead Ions, Metal-Ions, Model, Models, Parameters, Pb²⁺, pH, Predict, Process, Properties, Pseudo Second Order, Pseudo-Second-Order, Pseudo-Second-Order Model, Rate, Rate Constants, Retorted Shale, RS, Shale, Sorption, Spontaneous, Time, Waste-Water

? Kumar, G.P., Kumar, R.A., Chakraborty, S. and Ray, M. (2007), Uptake and desorption of copper ion using functionalized polymer coated silica gel in aqueous environment. Separation and Purification Technology, 57 (1), 47-56.

Full Text: 2007\Sep Pur Tec57, 47.pdf

Abstract: A resinous functionalized polymer, aniline formaldehyde condensate (AFC) coated on silica gel was used as an adsorbent to remove copper (Cu²⁺) from aqueous solution under conditions of different initial Cu²⁺ concentration, adsorbent loading, pH and adsorption time. Coordination bond formation between amine group and Cu²⁺ ion was the main mechanism of copper removal. Adsorption increased from 20% at pH 4 to 71% at pH 6 due to less competition from proton. Adsorption equilibrium was achieved within 120-150 min. The kinetics of adsorption followed second order model with rate constant of 0.0021 g/mg min. The adsorption data gave good fit with Langmuir isotherm and yielded Langmuir monolayer isotherm uptake of 76.33 mg/g and adsorption equilibrium parameter of 0.022 L/mg at solution pH of 5.4-5.7 and temperature of 22-25°C. During desorption studies 97-100% of adsorbed copper ion released in solution in presence of IN strength of mineral acids HCl, H₂SO₄ and HNO₃. Dynamic study shows that column breakthrough was achieved at 264 bed volume at initial Cu²⁺ of 25 mg/L. Further studies are recommended on regeneration and reuse of AFC coated silica gel after desorption of copper ion. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Acids, Adsorbent, Adsorption, Adsorption Equilibrium, Adsorption Time, Amine, Amine Group, Aniline, Aqueous Solution, Breakthrough, Cadmium, Coated Silica, Column, Competition, Concentration, Condensate, Coordination Bond, Copper, Copper Ion, Copper Removal, Copper Uptake And Desorption, Cu(II), Cu²⁺, Desorption, Desorption Studies, Environment, Equilibrium, Formaldehyde, Formation, Functionalized Polymer, Gel, Group, H₂SO₄, HCl, Heavy-Metals, HNO₃, Ion, Isotherm, Kinetics, Kinetics of Adsorption, Langmuir, Langmuir Isotherm, Langmuir Monolayer, Langmuir-Isotherm, Loading, Mechanism, Mineral, Model, Monolayer, Order, pH, Polyethyleneimine, Polymer, Proton, Rate, Rate Constant, Regeneration, Removal, Reuse, Second Order, Silica, Silica Gel, Solution pH, Sorption, Strength, Temperature, Time, Tree Fern, Uptake, Waste-Water

? Nie, H.L., Chen, T.X. and Zhu, L.M. (2007), Adsorption of papain on dye affinity membranes: Isotherm, kinetic, and thermodynamic analysis. Separation and Purification Technology, 57 (1), 121-125.

Full Text: 2007\Sep Pur Tec57, 121.pdf

Abstract: The adsorption of papain on the dye affinity membranes, the Cibacron Blue F3GA as a ligand, and the chitosan-coated nylon membrane as a base, under batch equilibrium experimental conditions at 277, 298, and 310K was investigated. The experimental data were analyzed using two adsorption kinetic models: the pseudo-first-order and the pseudo-second-order. The pseudo-second-order kinetic model provided the better correlation to the experimental results. Studies showed that the adsorption of papain on dye affinity membranes could be described by the Freundlich isotherm. The thermodynamic constants of adsorption phenomena: G°, H°, and S° were found as -12.58 kJ/mol (at 298 K), 17.81 kJ/mol, and 0.101 kJ/(mol K), respectively. The result shows that the adsorption of papain on the dye affinity membranes was endothermic and spontaneous. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: 298 K, 298-K, Adsorption, Adsorption Kinetic, Affinity, Affinity Membranes, Analysis, Base, Batch, Batch Equilibrium, Batch-Equilibrium, Biosorption, Chromatography, Cibacron Blue, Cibacron Blue F3ga, Constants, Correlation, Dye, Dye Affinity, Dye Affinity Membrane, Endothermic, Equilibrium, Experimental, Experimental Data, Freundlich, Freundlich Isotherm, G, Isotherm, Kinetic, Kinetic Model, Kinetic Models, Ligand, Lysozyme, Membrane, Membranes, Model, Models, Nylon, Papain, Phema, Pseudo Second Order, Pseudo Second Order Kinetic, Pseudo-First-Order, Pseudo-Second-Order, Pseudo-Second-Order Kinetic Model, Purification, Separation, Spontaneous, Thermodynamic, Thermodynamic Analysis

? Preetha, B. and Viruthagiri, T. (2007), Batch and continuous biosorption of chromium(VI) by Rhizopus arrhizus. Separation and Purification Technology, 57 (1), 126-133.

Full Text: 2007\Sep Pur Tec57, 126.pdf

Abstract: Biosorption of chromium using suspended and immobilized cells of Rhizopus arrhizus was studied by evaluating the physicochemical parameters of the solution such as initial chromium ion concentration in both batch and packed bed reactor. The Langmuir, Freundlich and Redlich-Peterson adsorption isotherm models were used in the equilibrium modeling. The Freundlich and Redlich-Peterson adsorption isotherm models were found to fit accurately with the experimental data. Batch experiments demonstrate that the sorption process corresponds to the second-order kinetic model and the kinetics of sorption indicates the process to be diffusion controlled. The diffusivity of chromium in Rhizopus-alginate gel beads was calculated using the shrinking core model, and the diffusivity values were in the ranges of 0.04910^-5 to 0.52110^-5 cm² s^-1. A good fit was found in the case of controlling intraparticle diffusion for the sorption of chromium. Thomas model, Adams-Bohart and Wolborska models were used to represent the dynamic sorption of chromium using immobilized beads and the model parameters were evaluated using experimental data. The Thomas model represents well the sorption of chromium at different residence times whilst Adams-Bohart model was fitted better at the initial part of the breakthrough. Wolborska model also represents the sorption of chromium accurately. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Activated-Sludge, Adams-Bohart Model, Adsorption, Adsorption Isotherm, Adsorption Isotherm Models, Aqueous-Solution, Batch, Beads, Bed, Biomass, Biosorption, Breakthrough, Cells, Chromium, Chromium Ion, Chromium(VI), Concentration, Copper, Core, Diffusion, Diffusivity, Dynamic, Dynamic Sorption, Equilibrium, Equilibrium Modeling, Experimental, Experimental Data, Experiments, Freundlich, Gel, Gel Beads, Immobilized, Immobilized Cells, Intraparticle Diffusion, Ion, Ions, Isotherm, Isotherm Models, Kinetic, Kinetic Model, Kinetic Modeling, Kinetics, Kinetics of Sorption, Langmuir, Model, Modeling, Models, Packed Bed, Parameters, Phenol, Physicochemical, Process, Reactor, Redlich-Peterson, Removal, Rhizopus Arrhizus, Second Order, Shrinking Core, Shrinking Core Model, Sorption, Thomas, Thomas Model

? Zhu, C.L., Luan, Z.K., Wang, Y.Q. and Shan, X.D. (2007), Removal of cadmium from aqueous solutions by adsorption on granular red mud (GRM). Separation and Purification Technology,