Personal Research Database

Full Text: 2007\J Haz Mat148, 771.pdf

Abstract: This letter discusses the discrepancies in thermodynamic studies in a recent article by Bouberka et al. Also presented is the significance of the separation factor R-L used to express the essential characteristics of Langmuir isotherm. In addition, the incorrect forms of the two kinetics rate equations, the pseudo-first-order and pseudo-second-order equations used by the authors, are also mentioned. (C) 2007 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Characteristics, Equations, Isotherm, Kinetics, Langmuir, Langmuir Isotherm, Langmuir-Isotherm, Models, Montmorillonite, Pseudo Second Order, Pseudo-First-Order, Pseudo-Second-Order, Rate, Recent, Separation, Separation Factor, Thermodynamic, Thermodynamic Parameters, Thermodynamic Studies

? Bulut, Y. and Tez, Z. (2007), Adsorption studies on ground shells of hazelnut and almond. Journal of Hazardous Materials, 149 (1), 35-41.

Full Text: 2007\J Haz Mat149, 35.pdf

Abstract: Adsorption behaviour of Ni(II), Cd(II) and Pb(II) from aqueous solutions by shells of hazelnut and almond were investigated. The structural properties and surface chemistry of the shells were characterized using sorption of nitrogen and Boehm titration. The equilibrium time was found to be 120 min. The equilibrium adsorption capacity of shells were obtained by using linear Langmuir and Freundlich adsorption isotherms. The equilibrium adsorption level was determined to be a function of the solution contact time, concentration and temperature. The thermodynamic parameters have been determined. The negative values of free change (G) indicated the spontaneous nature of the adsorption of Ni(II), Cd(II) and Pb(II) onto shells of hazelnut and almond and the positive values of enthalpy change (H) suggested the endothermic nature of the adsorption process, The best correlation coefficients were obtained for the pseudo second-order kinetic model. Ion exchange is probably one of the major adsorption mechanisms for binding divalent metal ions to the shells of hazelnut and almond. The selectivity order of the adsorbents is Pb(II) > Cd(II) > Ni(II). (C) 2007 Elsevier B.V. All rights reserved.

Keywords: Adsorbents, Adsorption, Adsorption Capacity, Adsorption Isotherms, Adsorption Mechanisms, Adsorption Process, Almond, Aqueous Solutions, Aqueous-Solutions, Behaviour, Binding, Capacity, Carbon, Cd(II), Change, Chemistry, Concentration, Contact, Copper(II), Correlation, Divalent Metal Ions, Endothermic, Enthalpy, Equilibrium, Equilibrium Time, Exchange, Freundlich, Function, Hazelnut, Heavy Metals, Heavy-Metal Ions, Ion Exchange, Ion-Exchange, Ions, Isotherms, Kinetic, Kinetic and Thermodynamic Parameters, Kinetic Model, Langmuir, Mechanisms, Metal, Metal Ions, Model, Modified Barks, Ni(II), Nitrogen, Pb(II), Process, Pseudo, Pseudo Second Order, Pseudo Second Order Kinetic, Pseudo Second-Order, Pseudo-Second-Order, Recovery, Removal, Rights, Sawdust Adsorption, Second Order, Second-Order, Selectivity, Solution, Solutions, Sorption, Spontaneous, Surface, Surface Chemistry, Temperature, Thermodynamic, Thermodynamic Parameters, Time, Values, Waste-Water

? Moura, M.N., Martín, M.J. and Burguillo, F.J. (2007), A comparative study of the adsorption of humic acid, fulvic acid and phenol onto Bacillus subtilis and activated sludge. Journal of Hazardous Materials, 149 (1), 42-48.

Full Text: 2007\J Haz Mat149, 42.pdf

Abstract: The adsorption of humic acid and fulvic acid onto Bacillus subtilis cells and activated sludge biomass was studied as a function of pH and incubation time. The adsorption of humic and fulvic acids was strongly pH-dependent and followed the same trend on both surfaces, increasing in a sigmoidal way with decreasing pH over the 2-10 pH range. This behaviour is explained in terms of hydrophobic interactions between the uncharged biomass and the uncharged humic and fulvic acids. In contrast, the adsorption of phenol onto B. subtilis cells and activated sludge biomass showed in both cases an optimum pH at around 7.0. This optimum value may be interpreted in terms of a combination of hydrophobic interactions and hydrogen bonds between undissociated phenol and polar groups on the cell walls. Kinetic studies on the adsorption of humic acid, fulvic acid and phenol onto B. subtilis cells and sludge biomass pointed to a rapid uptake of the substances, with an equilibrium time of about 30 min. In all cases, the kinetic curves were acceptably fitted by non-linear regression to an exponential function, suggesting a first-order kinetic phenomenon. The specific adsorption values collected at optimum pH revealed that with the materials used in this work both B. subtilis and activated sludge follow the same adsorption trend: humic > fulvic > phenol. The lower adsorption of fulvic acid as compared with humic acid may be explained in terms of its lower hydrophobicity rather than its lower molecular size. On comparing the specific adsorption values of activated sludge versus B. subtilis, similar but lower figures were found for the three organic compounds studied. This similar behaviour suggests that both types of biomass base their adsorption capacity on the general characteristics of the bacterial cell wall, and the lower adsorption by the sludge would be due to a lower specific area due to clustering of the cells. This is remarkable, since sludge is a heterogeneous and cheap material in comparison with cultured bacterial cells. (C) 2007 Elsevier B.V. All rights reserved.

Keywords: Activated Sludge, Adsorption, Adsorption Capacity, Adsorption, Biosorption, Bacillus, Bacillus Subtilis, Bacteria, Biomass, Biosorption, Capacity, Carbon, Chlorophenols, Comparative Adsorption, Biosorption, Comparative Study, Continuous Packed-Bed, Equilibrium, First Order, Fly-Ash, Fulvic Acid, Humic Acid, Kinetic, Kinetic Studies, Molecular, Organic Compounds, Ph, Phenol, Surfaces, Trend, Uptake, Waste-Water

? Nouri, L., Ghodbane, I., Hamdaoui, O. and Chiha, M. (2007), Batch sorption dynamics and equilibrium for the removal of cadmium ions from aqueous phase using wheat bran. Journal of Hazardous Materials, 149 (1), 115-125.

Full Text: 2007\J Haz Mat149, 115.pdf

Abstract: Studies on a batch sorption process using wheat bran as a low cost sorbent was investigated to remove cadmium ions from aqueous solution. The influence of operational conditions such as contact time, cadmium initial concentration, sorbent mass, temperature, solution initial pH, agitation speed and ionic strength on the sorption kinetics of cadmium was studied. Pseudo-second-order model was evaluated using the six linear forms as well as the non-linear curve fitting analysis method. Modeling of kinetic results shows that sorption process is best described by the pseudo-second-order model using the non-linear method. The sorption of cadmium was found to be dependent on initial concentration, sorbent mass, solution pH, agitation speed, temperature, ionic strength and contact time. The value of activation energy (12.38 kJ mol^-1) indicates that sorption has a low potential barrier corresponding to a physical process. Sorption equilibrium isotherms at different temperatures was determined and correlated with common isotherm equations such as Langmuir and Freundlich models. It was found that the Langmuir model appears to well fit the isotherm data but a worse correlation was obtained by the Freundlich model. The five Langmuir linear equations as well as the non-linear curve fitting analysis method were discussed. Results show that the non-linear method may be a better way to obtain the Langmuir parameters. Thermodynamic parameters such as H, S and G were calculated. These parameters indicate that the sorption of cadmium by wheat bran is a spontaneous process and physical in nature involving weak forces of attraction and is also endothermic. (C) 2007 Elsevier B.V. All rights reserved.

Keywords: Activation, Activation Energy, Adsorption, Agitation, Analysis, Aqueous Phase, Aqueous Solution, Barrier, Batch, Batch Sorption, Biosorbent, Biosorption, Cadmium, Cadmium Ions, Cd(II), Concentration, Contact Time, Copper(II), Correlation, Cost, Curve Fitting, Curve-Fitting, Dynamics, Endothermic, Energy, Equations, Equilibrium, Equilibrium Isotherms, Fitting, Freundlich, Freundlich Model, G, Heavy-Metals, Ionic Strength, Ions, Isotherm, Isotherm Data, Isotherms, Kinetic, Kinetics, Langmuir, Langmuir Isotherm, Langmuir Model, Lignin, Linear, Linear Analysis, Low, Low Cost Sorbent, Mass, Method, Model, Modeling, Models, Non-Linear, Non-Linear Analysis, Non-Linear Method, Nonlinear, Parameters, Pb(II), pH, Physical, Potential, Process, Pseudo Second Order, Pseudo-Second-Order, Pseudo-Second-Order Model, Removal, Solution pH, Sorbent, Sorption, Sorption Dynamics, Sorption Kinetics, Speed, Spontaneous, Strength, Temperature, Temperatures, Time, Value, Waste-Water, Wheat, Wheat Bran

? Kennedy, L.J., Vijaya, J.J., Sekaran, G. and Kayalvizhi, K. (2007), Equilibrium, kinetic and thermodynamic studies on the adsorption of m-cresol onto micro- and mesoporous carbon. Journal of Hazardous Materials, 149 (1), 134-143.

Full Text: 2007\J Haz Mat149, 134.pdf

Abstract: Investigations were conducted in batch mode to study the adsorption behaviour of m-cresol on a porous carbon prepared from rice husk (RHAC) by varying the parameters such as agitation time, m-cresol concentration (50-300 mg/l), pH (2.5-10) and temperature (293-323 K). Studies showed that the adsorption decreased with increase in pH and temperature. The isotherm data were fitted to Langmuir, Freundlich, and Dubinin-Radushkevic (D-R) models. The kinetic models such as pseudo-first-order, pseudo-second-order and intraparticle diffusion models were selected to understand the reaction pathways and mechanism of adsorption process. The thermodynamic equilibrium coefficients obtained at different temperatures were used to evaluate the thermodynamic constants G, H and S. The sorption process was found to be exothermic in nature (H: -23.46 to -25.40 kJ/mol) with a decrease in entropy (S: -19.44 to -35.87 J/(mol K)). The negative value of Gibbs free energy, G indicates that the adsorption occurs via a spontaneous process. The decrease in the value of -G from 17.70 to 13.54 kJ/mol with increase in pH and temperature indicates that the adsorption of m-cresol onto activated carbon is less favourable at higher temperature and pH range. The influence of mesopore and a possible mechanism of adsorption is also suggested. (C) 2007 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Activated Carbons, Adsorption, Adsorption Behaviour, Adsorption Process, Agitation, Agitation Time, and pH, Aqueous-Solutions, Batch, Batch Mode, Carbon, Concentration, Constants, Cr(VI), Diffusion, Diffusion Models, Energy, Entropy, Equilibrium, Exothermic, Free Energy, Free-Energy, Freundlich, G, Gibbs Free Energy, Intraparticle, Intraparticle Diffusion, Isotherm, Isotherm Data, Kinetic, Kinetic and Thermodynamic, Kinetic Models, Langmuir, Malachite Green, Mechanism, Mesopore, Mesoporous, Mesoporous Carbon, Models, Parameters, Pathways, pH, Phenol, Porous, Porous Carbon, Process, Pseudo Second Order, Pseudo-First-Order, Pseudo-Second-Order, Range, Reaction, Reaction Pathways, Removal, Rice, Rice Husk, Rice-Husk, Sawdust, Sorption, Spontaneous, Temperature, Temperatures, Thermodynamic, Thermodynamic Equilibrium, Thermodynamic Studies, Thermodynamics, Time, Value

? Someda, H.H. (2007), Influence of the support base on the sorption of Co(II) with mixed solvents. Journal of Hazardous Materials, 149 (1), 189-198.

Full Text: 2007\J Haz Mat149, 189.pdf

Abstract: Theonyltrifluoroacetone (TTA) mixed with trioctyl phosphine oxide (TOPO) have been supported on Amberlite XAD-4, silica gel and wood powder. The resulting resins have been used to study the sorption of cobalt(II) from acetate buffer and their sorption capacities were determined and were found to be 12.38, 11.61 and 6.51 mg g^-1 for TTA + TOPO/Amberlite XAD4, TTA + TOPO/silica gel and TTA + TOPO/wood, respectively. The experimental results showed that the sorption of Co(II) increases with its initial concentration. The results can be fitted by Freundlich isotherm in the studied cobalt concentration range [10^-4-10^-3 M] and 1/n values are 1.07, 1.17 and 1.73 for Amberlite XAD4, silica gel and wood powder, respectively. The sorption of Co(II) onto the prepared resins was found to follow the pseudo-second order model and the sorption rate have the values 8.7910, 1010^-3 and 1610^-3 g mg^-1 min^-1 for Amberlite XAD4, silica gel and wood powder, respectively. Thermodynamic parameters have also been calculated for the three systems and sorption process was found to be spontaneous and endothermic one. (C) 2007 Elsevier B.V. All rights reserved.

Keywords: Acetate, Acid Solution, Adduct Formation, Amberlite XAD-4, Aqueous-Solutions, Buffer, Co(II), Cobalt, Cobalt(II), Concentration, Endothermic, Equilibrium, Experimental, Extraction Chromatography, Freundlich, Freundlich Isotherm, Gel, Isotherm, Ligands, Metal-Ions, Model, Oxide, Pseudo Second Order, Pseudo-Second Order, Pseudo-Second Order Model, Pseudo-Second-Order, Removal, Resins, Rights, Separation, Silica, Silica Gel, Sorption, Sorption Process, Support, Systems, Thermodynamic, Thermodynamic Parameters, TOPO, Tree Fern, TTA, Wood, XAD-4

? Lu, S.G., Gibb, S.W. and Cochrane, E. (2007), Effective removal of zinc ions from aqueous solutions using crab carapace biosorbent. Journal of Hazardous Materials, 149 (1), 208-217.

Full Text: 2007\J Haz Mat149, 208.pdf

Abstract: The carapace of the crab (Cancer pagurus), a waste material disposed of by the seafood industry, has recently been shown to have potential as a biosorbent for the removal of metals from aqueous media. Crab carapace in the particle size ranges 0.25-0.8 ram and 0.8-1.5 mm were used to investigate the effects of agitation speed, contact time, metal concentration and initial pH on the removal of Zn²⁺. In sequential-batch process Zn²⁺ uptakes of 105.6 and 67.6 mg, g were recorded for 0.25-0.8 mm and 0.8-1.5 nun particles, respectively, while values of 141.3 and 76.9 mg, g were recorded in fixed-bed column studies. Binary-metal studies showed that the presence of Cu²⁺ or Pb²⁺ significantly suppressed Zn²⁺ uptake. This study confirms that crab carapace may be considered a viable and cost-effective alternative to commercial activated carbon or ion-exchange resins for the removal of metals from aqueous media. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Adsorption, Agitation, Alternative, Aqueous Solutions, Biosorbent, Biosorption, Biosorption, Cancer, Carbon, Column, Column Studies, Concentration, Contact, Copper, Cost-Effective, Crab Carapace, Cu²⁺, Effects, Equilibrium, Fixed Bed, Fixed-Bed Column, Heavy-Metals, Industry, Ion Exchange, Ion Exchange Resins, Ion-Exchange, Ionexchange, Ions, Kinetics, Media, Metal, Metals, Mixed Mineral Systems, Particle Size, Particles, Pb²⁺, pH, Potential, Presence, Process, Removal, Resins, Rights, Seafood, Sequential-Batch Process, Shell Particles, Size, Solutions, Speed, Time, Uptake, Values, Waste, Waste Material, Zinc, Zn²⁺

? Veli, S. and Alyüz, B. (2007), Adsorption of copper and zinc from aqueous solutions by using natural clay. Journal of Hazardous Materials, 149 (1), 226-233.

Full Text: 2007\J Haz Mat149, 226.pdf

Abstract: In this study, removal of copper (CU²⁺) and zinc (Zn²⁺) from aqueous solutions is investigated using Cankiri bentonite, a natural clay. During the removal process, batch technique is used, and the effects of pH, clay amount, heavy metal concentration and agitation time on adsorption efficiency are studied. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms are applied in order to determine the efficiency of natural clay used as an adsorbent. Results show that all isotherms are linear. It is determined that adsorption of CU²⁺ and Zn²⁺ is well-fitted by the second order reaction kinetic. In addition, calculated and experimental heavy metal amounts adsorbed by the unit clay mass are too close to each other. It is concluded that natural clay can be used as an effective adsorbent for removing CU²⁺ and Zn²⁺ from aqueous solutions. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Adsorbent, Adsorption, Adsorption Efficiency, Agitation, Agitation Time, Aqueous Solutions, Batch, Bentonite, Cd, Clay, Concentration, Copper, Copper and Zinc, Cu²⁺, D-R Isotherm, Dye, Effective, Effects, Effects of pH, Efficiency, Experimental, Freundlich, Freundlich Isotherm, Heavy Metal, Heavy-Metal, Heavy-Metal Removal, Ions, Isotherms, Kinetic, Langmuir, Langmuir Isotherm, Linear, Mass, Metal, Molecules, Montmorillonite, Natural, Natural Clay, Order, Peat, pH, Process, Reaction, Reaction Kinetic, Removal, Removal Process, Removing, Second Order, Solutions, Sorption, Time, Water, Zinc, Zn²⁺

? Khormaei, M., Nasernejad, B., Edrisi, M. and Eslamzadeh, T. (2007), Copper biosorption from aqueous solutions by sour orange residue. Journal of Hazardous Materials, 149 (2), 269-274.

Full Text: 2007\J Haz Mat149, 269.pdf

Abstract: In this study, copper uptake by sour orange residue (SOR) was investigated. Equilibrium isotherms and kinetics were obtained and the effects of solution pH, temperature, and particle size were studied in batch experiments. Equilibrium was well described by Langmuir and Freundlich isotherms and kinetics was found to be best-fit pseudo-second order equations. Maximum uptake was observed at pH 5. With an increase in temperature from 20 to 50C, copper removal decreased about 20%. Additional chemical treatment of the biosorbent by NaOH, increased the biosorption capacity. It was found that increase in biosorbent particle size had no significant effects on the final equilibrium concentration, but decreased biosorption rate. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Aqueous Solutions, Batch, Batch Experiments, Biosorbent, Biosorption, Biosorption Capacity, Capacity, Chemical, Chemical Treatment, Concentration, Copper, Copper Removal, Cr(III), Cu(II), Effects, Equations, Equilibrium, Equilibrium Concentration, Experiments, Freundlich, Freundlich Isotherms, Heavy-Metals, Ions, Isotherms, Kinetic, Kinetics, Langmuir, Langmuir and Freundlich Isotherms, NaOH, Ni(II), Order, Particle, Particle Size, Pb(II), pH, Pseudo Second Order, Pseudo-Second Order, Pseudo-Second-Order, Rate, Removal, Removal, Residue, Size, Solution pH, Solutions, SOR, Sour Orange, Temperature, Treatment, Uptake, Wastewaters, Water

? Sari, A., Tuzen, M., Citak, D. and Soylak, M. (2007), Equilibrium, kinetic and thermodynamic studies of adsorption of Pb(II) from aqueous solution onto Turkish kaolinite clay. Journal of Hazardous Materials, 149 (2), 283-291.

Full Text: 2007\J Haz Mat149, 283.pdf

Abstract: The adsorption of Pb(II) onto Turkish (Bandirma region) kaolinite clay was examined in aqueous solution with respect to the pH, adsorbent dosage, contact time, and temperature. The linear Langmuir and Freundlich models were applied to describe equilibrium isotherms and both models fitted well. The monolayer adsorption capacity was found as 31.75 mg/g at pH 5 and 20C. Dubinin-Radushkevich (D-R) isotherm model was also applied to the equilibrium data. The mean free energy of adsorption (13.78 kJ/mol) indicated that the adsorption of Pb(II) onto kaolinite clay may be carried out via chemical ion-exchange mechanism. Thermodynamic parameters, free energy (G), enthalpy (H) and entropy (S) of adsorption were also calculated. These parameters showed that the adsorption of Pb(II) onto kaolinite clay was feasible, spontaneous and exothermic process in nature. Furthermore, the Lagergren-first-order, pseudo-second-order and the intraparticle diffusion models were used to describe the kinetic data. The experimental data fitted well the pseudo-second-order kinetics. (c) 2007 Elsevier B.V All rights reserved.

Keywords: Adsorbent, Adsorption, Adsorption Capacity, Adsorption Isotherm, Aqueous Solution, Capacity, Chemical, Clay, Data, Diffusion, Energy, Enthalpy, Entropy, Equilibrium, Exothermic, Experimental, Freundlich, Intraparticle Diffusion, Ion Exchange, Ion-Exchange, Ionexchange, Isotherm, Isotherm Model, Isotherms, Kaolinite, Kaolinite Clay, Kinetic, Kinetics, Langmuir, Mechanism, Model, Models, Monolayer, Pb(II), pH, Pseudo Second Order, Pseudo Second Order Kinetics, Pseudo-Second-Order, Pseudo-Second-Order Kinetics, Solution, Temperature, Thermodynamic, Thermodynamic Parameters, Thermodynamic Studies, Thermodynamics, Turkish Kaolinite Clay

? Chen, H., Zhao, Y.G. and Wang, A.Q. (2007), Removal of Cu(II) from aqueous solution by adsorption onto acid-activated palygorskite. Journal of Hazardous Materials, 149 (2), 346-354.

Full Text: 2007\J Haz Mat149, 346.pdf

Abstract: A series of activated palygorskite clay by HCl with different concentrations was prepared and applied as adsorbents for removal of Cu(II) from aqueous solutions. The effects of contact time, adsorbent dosages and pHs of suspension on the adsorption capacities for Cu(II) were investigated. The results showed that adsorption capacity of activated palygorskites increased with increasing the HCl concentration and the maximum adsorption capacity with 32.24 mg/g for Cu(II) is obtained at 12 mol/L of HCl concentration. The variations in IR spectra and pH of solution after adsorption Cu(II) confirmed that the numerous amount of silanol groups (Si-OH) originated by acid treatment were mainly responsible for Cu(II) adsorption onto acid-activated palygorskite. Kinetic studies indicated that the adsorption mechanisms in the Cu(II)/acid-activated palygorskite system followed the pseudo-second-order kinetic model with a relatively small contribution of film diffusion. Equilibrium data fitted well with Freundlich isotherm model compared to Langmuir isotherm model, indicating that adsorption takes place on heterogeneous surfaces of the acid-activated palygorskite. Adsorption-desorption studies presented that activated palygorskite has lower adsorption and desorption efficiencies using Cu(CH3COO)(2) than that of other inorganic copper salts, such as CUSO4, Cu(NO3)(2), and CUCl2. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Acid, Acid Treatment, Acid-Activation, Acid-Treatment, Adsorbent, Adsorbents, Adsorption, Adsorption and Desorption, Adsorption Capacities, Adsorption Capacity, Adsorption Mechanisms, and pH, Aqueous Solution, Aqueous Solutions, Attapulgite, Capacity, Clay, Concentration, Concentrations, Contact Time, Copper, Copper, Cu(II), Cu(II) Adsorption, Desorption, Diffusion, Effects, Exchange, Film, Film Diffusion, Freundlich, Freundlich Isotherm, Groups, HCl, Heavy-Metals, Heterogeneous, Heterogeneous Surfaces, Inorganic, IR, IR Spectra, Isotherm, Isotherm Model, Kinetic, Kinetic Model, Kinetics, Langmuir, Langmuir Isotherm, Langmuir Isotherm Model, Langmuir-Isotherm, Mechanisms, Model, Montmorillonite, Palygorskite, Palygorskite Clay, pH, Pseudo Second Order, Pseudo Second Order Kinetic, Pseudo-Second-Order, Pseudo-Second-Order Kinetic Model, Removal, Retention, Salts, Sepiolite, Silanol, Silanol Groups, Solutions, Sorption, Spectra, Surfaces, Suspension, Time, Treatment

? Altundogan, H.S., Arslan, N.E. and Tumen, F. (2007), Copper removal from aqueous solutions by sugar beet pulp treated by NaOH and citric acid. Journal of Hazardous Materials, 149 (2), 432-439.

Full Text: 2007\J Haz Mat149, 432.pdf

Abstract: Sugar beet pulp was converted into effective copper sorption material by treating subsequently with NaOH and citric acid. Compared with the untreated sugar beet pulp, the cation exchange capacity of the modified sugar beet pulp increased from 0.86 to 3.21 mequiv. G^-1. Swelling capacity and COD values of modified sugar beet pulp were found to be decreased in the ratio of 38% and 61%, respectively, compared to the corresponding values of native sugar beet pulp, meaning that modification causes stabilization. Sorption characteristics of the modified sugar beet pulp towards copper ions were studied with batch experiments. Pseudo-first, pseudo- second-order and intraparticle kinetic models were applied to the kinetic data and it was found that the sorption processes followed the pseudo-second-order rate kinetics with activation energy of 16.34 kJ mol^-1. The equilibration data fit best with the Langmuir isotherm the maximum copper sorption capacity of which is 119.43 ing g^-1. The mean free energy of copper sorption process calculated from Dubinin-Radushkevich model and the Polanyi potential concept was found to be in the range of 10.91-11.95 kJ mol^-1 showing that the main mechanism governing the sorption process is ion exchange. The negative values found for enthalpy change (-14.797 kJ mol^-1 over the range of 25-55C and free energy change (-19.361 kJ mol^-1 for 25C) indicate that the sorption process is exothermic and spontaneous in nature. (c) 2007 Elsevier B.V. All rights reserved.

Keywords: Activated Carbon, Activation, Activation Energy, Adsorption, Aqueous Solutions, Batch, Batch Experiments, Binding-Properties, Capacity, Cation, Cation Exchange, Cation Exchange Capacity, Change, Characteristics, Citric Acid, COD, Copper, Copper Ions, Copper Sorption Characteristics, Data, Divalent Metal-Cations, Energy, Enthalpy, Epichlorohydrin, Equilibration, Exchange, Exothermic, Experiments, Improvement, Intraparticle, Ion Exchange, Ion-Exchange, Ions, Isotherm, Kinetic, Kinetic Models, Kinetics, Langmuir, Langmuir Isotherm, Meaning, Mechanism, Model, Models, Modification, Modified, Modified Sugar Beet Pulp, NaOH, Potential, Process, Pseudo, Pseudo Second Order, Pseudo-Second-Order, Pseudo-Second-Order Rate, Rate Kinetics, Removal, Rights, Second Order, Second-Order, Solutions, Sorption, Sorption Capacity, Sorption Process, Soybean Hull, Spontaneous, Stabilization, Starch, Sugar, Sugar Beet Pulp, Swelling, Values

? Uysal, M. and Ar, I. (2007), Removal of Cr(VI) from industrial wastewaters by adsorption. Part I: Determination of optimum conditions. Journal of Hazardous Materials,