Personal Research Database

Full Text: 1996\Sep Sci Tec31, 2359.pdf

Abstract: Acrylamide/maleic acid (AAm/MA) hydrogels prepared by irradiating with gamma-radiation were used in experiments on swelling, diffusion, and uptake of some cationic dyes such as basic red 9 (BR-9), basic green 4 (BG-4), cresyl violet (CV), and basic blue 20 (BB-20). AAm/MA hydrogel containing 60 mg maleic acid and irradiated at 5.71 kGy has been used for swelling and diffusion studies in water and solutions of basic dyes. For this hydrogel, swelling studies indicated that swelling increased in the following order, BR-9 > BG-4 > CV > BB-20 > water. Diffusion of water and the dyes within hydrogels was found to be of a non-Fickian character. The uptake of the cationic dyes to AAm/MA hydrogels is studied by the batch adsorption technique at 25C. In the adsorption experiments, Langmuir-type adsorption in the Giles classification system was found. Some binding and thermodynamic parameters for AAm/MA hydrogel-dye systems were calculated by using the Klotz method. Adsorption studies indicated that monolayer coverages of AAm/MA hydrogel by these dyes increased in the following order: BB-20 > CV > BG-4 > BR-9.

Keywords: Hydrogel, Poly(Acrylamide/Maleic Acid), Swelling, Adsorption, Cationic Dyes, Bovine Serum-Albumin, Adsorption, N-Vinyl-2-Pyrrolidone, Methacrylate, Binding

Chen, J.P. and Yiacoumi, S. (1997), Biosorption of metal ions from aqueous solutions. Separation Science and Technology, 32 (1-4), 51-69.

Full Text: 1997\Sep Sci Tec32, 51.pdf

Abstract: Copper biosorption from aqueous solutions by calcium alginate is reported in this paper. The experimental section includes potentiometric titrations of biosorbents, batch equilibrium and kinetic studies of copper biosorption, as well as fixed-bed biosorption experiments. The potentiometric titration results show that the surface charge increases with decreasing pH. The biosorption of copper strongly depends on solution pH, the metal ion binding increases from 0 to 90 percent in pH ranging from 1.5 to 5.0. In addition, a decrease in ionic strength results in an increase of copper ion removal. Kinetic studies indicate that mass transfer plays an important role in the biosorption rate. Furthermore, a fixed-bed biosorption experiment shows that calcium alginate has a significant capacity for copper ion removal. The two-pK Basic Stern model Successfully represents the surface charge and equilibrium biosorption experimental data. The calculation results demonstrate that the copper removal may result from the binding of free copper and its hydroxide with surface functional groups of the biosorbents.

Keywords: Alginate Gel Beads, Modeling Adsorption, Interface, Sorption, Biomass, pH

Lee, S.H. and Yang, J.W. (1997), Removal of copper in aqueous solution by apple wastes. Separation Science and Technology, 32 (8), 1371-1387.

Full Text: 1997\Sep Sci Tec32, 1371.pdf

Abstract: Removal of copper from a solution was investigated to evaluate the cation-exchange capacities of apple residues from agricultural wastes. The effects of solution pH, ionic strength, co-ion, ligands, initial metal concentrations, and particle size of apple residues were studied. The optimal pH range for copper removal by apple residues was shown to be from pH 5.5 to 7.0, and the maximum percentage of copper removal was 91.2%. Increasing ionic strength, up to 0.1 N, has little effect on metal uptake. The presence of co-ions such as lead decreases the removal capacity of copper as expected. The presence of ligands, such as EDTA and ammonia, also reduces metal removal efficiency due to the formation of a metal-ligand complexation in solution. Equilibrium of copper sorption was established very rapidly initially and decreased markedly after 1 hour. Equilibrium isotherms of copper fit the Langmuir equation adequately. Column experiments showed that the dynamic capacity of chemically modified apple residues was four to five times higher than that of raw residues which contained acidic groups such as carboxylic and phenolic functional groups. The adsorbed copper ions were completely recovered with three bed volumes of 0.5 N HCl. Thus, modified apple residues could be applied successfully for metal removal from wastewater.

Keywords: Biosorption

Huang, J.G. and Liu, J.C. (1997), Enhanced removal of As(V) from water with iron-coated spent catalyst. Separation Science and Technology, 32 (9), 1557-1569.

Full Text: 1997\Sep Sci Tec32, 1557.pdf

Abstract: The effectiveness of pretreating a spent catalyst with an iron-salt solution to improve its As(V) removal capacity was studied. Various factors, such as types and concentrations of iron salt, pH, and initial As(V) concentration were investigated for their effects on the improvement of As(V) removal capacity. A significant increase in As(V) removal capacity can be achieved by iron-coated spent catalyst. Adsorption density of As(V) decreased with increasing pH. Langmuir adsorption isotherm was utilized to describe the adsorption reaction. Results from IR analysis and zeta potential measurement indicate that As(V) is specifically adsorbed onto iron-coated spent catalyst. This study shows that spent catalyst can be converted to a useful adsorbent for As(V) removal.

Keywords: Adsorption, Arsenic, pH, Spent Catalyst, Zeta Potential, Activated Carbon, Adsorption, Hydroxide, Flotation, Sorption, Copper, Sand

? Zouboulis, A.I., Matis, K.A., Lanara, B.G. and Loos-Neskovic, C. (1997), Removal of cadmium from dilute solutions by hydroxyapatite. II. Flotation studies. Separation Science and Technology, 32 (10), 1755-1767.

Full Text: 1997\Sep Sci Tec32, 1755.pdf

Abstract: Dissolved-air flotation has been investigated in the present paper as a suitable solid/liquid separation technique, applied downstream for hydroxyapatite ultrafine particles which were used in a preliminary stage for the removal by sorption of toxic cadmium cations. The main parameters affecting this process were evaluated, including the necessary quantity of sorbent material in the dispersion, the proper pH values of Cd solutions, the type and concentration of supplementary inorganic flocculant agents (ferric chloride and aluminum sulfate), and the presence of additional surfactant added. The results obtained were considered to be promising. Under optimum conditions, over 95% of Cd-loaded hydroxyapatite particles were separated in a very short retention time.

Keywords: Metal-Ions, Minerals

Hasany, S.M., Najamuddin, and Ikram, M. (1997), Uptake of traces of selenite by manganese dioxide from aqueous solutions. Separation Science and Technology, 32 (12), 1945-1957.

Full Text: 1997\Sep Sci Tec32, 1945.pdf

Abstract: Sorption of selenite onto manganese dioxide has been investigated with respect to shaking time, concentration of sorbent and sorbate, nature of electrolyte, and influence of cations and anions. The sorption of other metal ions has been studied using optimal conditions selected for maximum sorption of selenite. The surface area, average pore diameter, porosity, and solid phase density of the sorbent have been measured. The sorption data followed only the Dubinin-Radushkevich (D-R) sorption isotherm among all the isotherms tested. The sorption capacity of 51.2 nmol.g^-1 and a constant beta related to sorption energy have been estimated to be -0.007521 mol².kJ^-2. The sorption energy is found to be 8.15 kJ.mol^-1. The kinetics of the sorption follows the Lagergren equation in the initial stages. The first-order rate constant, k’, was evaluated to be 0.498 min^-1 and of intraparticle diffusion rate 3.06×10^-5 mol.g^-.min^-2. Among all the anions and cations tested, only carbonate, Fe(III), and citrate reduced the sorption significantly. The sorption data for other metal ions showed that Te(IV) can be separated from ions showing higher degree of sorption, especially Se(IV), As(III), Sb(V), and Eu(III). It can be concluded that manganese dioxide may be used for the separation of certain metal ions, their preconcentration from very dilute solutions, and for de contamination and treatment of industrial effluents.

Keywords: Adsorption Behavior, Acid-Solutions, Microamounts

? Petersen, F.W. and Van Deventer, J.S.J. (1997), Competitive adsorption of gold cyanide and organic compounds onto porous adsorbents. Separation Science and Technology, 32 (13), 2087-2103.

Full Text: 1997\Sep Sci Tec32, 2087.pdf

Abstract: Activated carbon has had a tremendous impact on the technology of gold recovery from leached liquors. Ion-exchange resins have been proposed as possible alternatives to carbon, while ion- exchange fibers and membranes were investigated recently as adsorbents for metal recovery in view of their fast rate of uptake. This paper deals with the competitive adsorption of organic compounds and gold cyanide onto activated carbon, ion- exchange resin, ion-exchange fiber, and membrane. Loadings of organic compounds were measured on gold equilibrated adsorbents and compared to loadings on virgin adsorbents. Both the kinetic and equilibrium parameters in a film/surface diffusion model were affected, which indicated a competitive type of mechanism between gold cyanide and organic compounds. A two-component Freundlich-type isotherm fitted the equilibrium for adsorption on carbon, membrane, and fiber. Furthermore, low molecular mass organic substances revealed a smaller inhibiting effect on gold adsorption than long-chain or high molecular mass organic compounds

Keywords: Activated Carbon, Adsorption, Membrane

Hsu, Y.C., Chiang, C.C. and Yu, M.F. (1997), Adsorption behavior of basic dyes on activated clay. Separation Science and Technology, 32 (15), 2513-2534.

Full Text: 1997\Sep Sci Tec32, 2513.pdf

Abstract: Activated clay was used to study the adsorption behavior of dyestuffs in synthetic wastewater containing dyestuffs. Three basic dyes were used: C.I. Basic Red 18 (or BR18), C.I. Basic Red 46 (BR46), and C.I. Basic Yellow 28 (BY28). Adsorption occurred almost instantaneously upon contact. The mechanism of adsorption was explained by a charge to the electrostatic attractive force described in the Langmuir adsorption isotherm. The mass transfer coefficient was also calculated by the external mass transfer model in an adsorbent according to McKay et al. Parameters including species of basic dyes, initial concentration, temperature, size of adsorbent, and NaCl were extensively investigated.

Keywords: Aqueous-Solutions, Transport Processes, Bagasse Pith, Fly-Ash, Removal, Particles, Adsorption, Activated Clay, Wastewater, Basic Dye, Mass Transfer

Gupta, V.K., Rastogi, A., Dwivedi, M.K. and Mohan, D. (1997), Process development for the removal of zinc and cadmium from wastewater using slag: A blast furnace waste material. Separation Science and Technology, 32 (17), 2883-2912.

Full Text: 1997\Sep Sci Tec32, 2883.pdf

Abstract: Blast furnace slag, a waste generated in steel plants in India, has been converted into a low cost potential adsorbent. The resulting product has been characterized and used for the removal of zinc and cadmium. The effect of particle size, contact time, and surface loading of zinc and cadmium on the adsorbent for their removal have been studied at the optimum pH (6.0 for Zn²⁺ and 5.0 for Cd²⁺). Kinetic studies were undertaken to show the mechanistic aspects of the process and to obtain the thermodynamic parameters. Sorption data have been correlated with both Langmuir and Freundlich adsorption models. Column operations were also performed in an attempt to simulate industrial conditions. Some feasibility experiments have been performed with a view to recovering Zn²⁺ and Cd²⁺ and for the chemical regeneration of the spent columns without dismantling them.

Keywords: Metal-Ions, Adsorption, Water, Lead, Equilibrium, Copper(II), Adsorbent, Chromium, Slurry, Blast Furnace Slag, Adsorption, Wastewater Treatment, Adsorbent, Zinc and Cadmium

Smith, E.H. (1998), Modeling batch kinetics of cadmium removal by a recycled iron adsorbent. Separation Science and Technology, 33 (2), 149-168.

Full Text: 1998\Sep Sci Tec33, 149.pdf

Abstract: The kinetics of cadmium adsorption onto a recycled iron-bearing material is investigated. Batch rate data are analyzed using a surface reaction rate model, solved analytically, and a dual rate diffusion model solved numerically. Experimental investigations examined the effects of sorbent particle size in the 0.06-0.5 mm diameter range and pH in the 4-7 range. While both rate models can describe time-concentration data for cadmium well, particularly for the larger granular sizes of sorbent, the analysis reveals a substantial variation in the relevant rate coefficients with particle radius, r, suggesting diffusion versus surface-controlled reaction kinetics. The second-order rate constant for the surface reaction model and the intraparticle diffusion coefficient of the dual rate diffusion model, represented as surface diffusion, were proportional to 1/r.

Keywords: Adsorption, Batch Kinetics, Cadmium, Diffusion, Iron Fines, Surface Reaction, Heavy-Metals, Adsorption, Oxide, Oxyhydroxide, Lead

? Biškup, B. and Subotić, B. (1998), Removal of heavy metal ions from solutions by means of zeolites. I. Thermodynamics of the exchange processes between cadmium ions from solution and sodium ions from zeolite A. Separation Science and Technology, 33 (4), 449-466.

Full Text: 1998\Sep Sci Tec33, 449.pdf

Abstract: Relationships between corrected selectivity coefficient (K-C) and fraction of the exchanged cadmium ions in zeolite A (f(Cd, z)) were determined from data obtained by measuring the concentrations of sodium and cadmium ions in both the solid and the liquid phase at equilibrium of the exchange processes between cadmium ions from solution and sodium ions from zeolite A at different total ion concentrations and different temperatures. Thermodynamic equilibrium constants (K-a) calculated from the corresponding Kielland’s plots (K-C vs f(Cd, z) plots) were used for the calculation of the appropriate values of standard free energy (G°) standard enthalpy (H°), and standard entropy (°). The influence of the degree of exchange on the activity coefficients of sodium and cadmium ions in zeolite is also considered.

Keywords: Zeolite A, Ion Exchange, Sodium Ions, Cadmium Ions, Exchange Equilibrium, Thermodynamic Data, Waste-Water

? Colella, C., De’ Gennaro, M., Langella, A. and Pansini, M. (1998), Evaluation of natural phillipsite and chabazite as cation exchangers for copper and zinc. Separation Science and Technology, 33 (4), 467-481.

Full Text: 1998\Sep Sci Tec33, 467.pdf

Abstract: Chabazite and phillipsite, two zeolites widespread in many volcaniclastic deposits in central-southern Italy, were evaluated as cation exchangers for the removal of copper and zinc from aqueous solution. Equilibrium and kinetics of copper and zinc exchange reactions for sodium were investigated in order to verify the selectivity and the uptake rate of both zeolites for these heavy metals. Thermodynamic quantities, such as equilibrium constant, K-a, and Delta G degrees, as well as rate constant, K, were computed, and they showed that Na-chabazite displays a moderate selectivity and a favorable kinetics for copper, whereas in ail the other cases uses in wastewater treatment are not recommended.

Keywords: Chabazite, Phillipsite, Ion Exchange, Copper, Zinc, Ion-Exchange, Lead Removal, Selectivity, Equilibria, Zeolites, Water

? Biškup, B. and Subotić, B. (1998), Removal of heavy metal ions from solutions by means of zeolites. I. Thermodynamics of the exchange processes between cadmium ions from solution and sodium ions from zeolite A. Separation Science and Technology, 33 (4), 449-466.

Full Text: 1998\Sep Sci Tec33, 449.pdf

Abstract: Relationships between corrected selectivity coefficient (K-C) and fraction of the exchanged cadmium ions in zeolite A (f(Cd,z)) were determined from data obtained by measuring the concentrations of sodium and cadmium ions in both the solid and the liquid phase at equilibrium of the exchange processes between cadmium ions from solution and sodium ions from zeolite A at different total ion concentrations and different temperatures. Thermodynamic equilibrium constants (K-a) calculated from the corresponding Kielland’s plots (K-C vs f(Cd,z) plots) were used for the calculation of the appropriate values of standard free energy (Delta G degrees) standard enthalpy (Delta H degrees), and standard entropy (Delta S degrees). The influence of the degree of exchange on the activity coefficients of sodium and cadmium ions in zeolite is also considered.

Keywords: Cadmium, Cadmium Ions, Exchange Equilibrium, Heavy Metal, Heavy Metal Ions, Ion Exchange, Selectivity, Selectivity Coefficient, Sodium Ions, Thermodynamic Data, Waste-Water, Zeolite, Zeolite A, Zeolites

Chang, J.S. and Chen, C.C. (1998), Quantitative analysis and equilibrium models of selective adsorption in multimetal systems using a bacterial biosorbent. Separation Science and Technology, 33 (5), 611-632.

Full Text: 1998\Sep Sci Tec33, 611.pdf

Abstract: This study investigated the behavior of selective adsorption on the biomass of Pseudomonas aeruginosa PU21 (Rip64) with solutions containing Pb, Cu, and Cd. Experiments were designed to quantitatively justify the biosorption preference of the biomass for the three metals. The multimetal adsorption equilibria were described by three models, two of which originated from single-component Langmuir isotherm, and the third one was established empirically. The multimetal adsorption results show that lead and copper significantly inhibited the adsorption of cadmium, while the effects of Cd on the adsorption of Cu and Pb were limited Lead was found to exhibit a slightly higher inhibition effect on Cu when the two adsorbate coexisted. The data obtained from the ion-exchange systems indicate that Pb and Cu appreciably replaced the preadsorbed Cd ions from the biosorbent, but the competition of Pb and Cu for the adsorption sites was comparative. For three-metal biosorption with equal initial molar concentrations, the relative surface coverage of Pb, Cu, and Cd on the biomass was approximately 55, 40, and 5%, respectively. A modified Langmuir-type model (Model 2), which took account of the heterogeneity and specificity of the adsorption sites, described the experimental results better than the traditional Langmuir isotherm (Model 1) did. of the three models examined, the empirical one (Model 3) showed the best fits for the two-metal adsorption data, whereas Model 2 had better prediction for the ternary adsorption results. In Model 3 the parameters determined from binary systems can be extrapolated to predict the adsorption equilibria of three-metal adsorption systems satisfactorily.

Keywords: Biosorption, Metals, Biomass, Removal, Cells

Tikhonov, N.A. and Zagorodni, A.A. (1998), Simulation of dual temperature ion-exchange separation process taking into account complex formation in solution. Separation Science and Technology, 33 (5), 633-653.

Full Text: 1998\Sep Sci Tec33, 633.pdf

Abstract: A mathematical modeling of a dual temperature ion-exchange separation system is reported. The nonlinear nonequilibrium model created takes into account the following physicochemical processes: kinetics, ion-exchange reactions, complex formation accomplishing the chemical equilibria The model was applied for a system containing Cu²⁺ and Zn²⁺ in acidic sulfate solutions and the iminodiacetic ion-exchange resin Amberlite IRC-718. Good agreement to the experimental data was found. The dependence of the separation efficiency on different factors was tested. The advantage of nonequilibrium operations for the effective separation was shown. The optimal separation cycle was calculated for a sulfate solution containing 2.5 mM Cu and 20 mM Zn at pH 2.05. An ion-exchange column can process 207 bed volumes of the treated solution during one cycle. The effluent is separated for three fractions. The first fraction (75 bed volumes) is the solution containing the 9 times reduced Cu concentration. The second one (36 bed volumes) is the concentrate of Cu. The third Fraction is mixed and recycled for repeated treatment.

Alam, M.S., Inoue, K., Yoshizuka, K. and Ishibashi, H. (1998), Adsorptive separation of rhodium(III) using Fe(III)-templated oxine type of chemically modified chitosan. Separation Science and Technology, 33 (5), 655-666.

Full Text: 1998\Sep Sci Tec33, 655.pdf

Abstract: The oxine type of chemically modified chitosan was prepared by the template crosslinking method using Fe(III) as a template ion. Batchwise adsorption of rhodium(II) on this chemically modified chitosan was examined from chloride media in the absence and presence of a large amount of tin(II). It was observed that the Fe(III)templated oxine type of chemically modified chitosan shows better performance for rhodium adsorption than that of the original chitosan. When Sn(II) is absent from the solution, Rh(III) is hardly adsorbed on the modified chitosan and the order of selectivity of the adsorption of Rh(III), Pt(IV), and Cu(II) was found to be Pt(IV) > Cu(II) approximate to Rh(III). On the other hand, adsorption of rhodium is significantly increased in the presence of Sn(II) and the selectivity order of the adsorption was drastically changed to Rh(LII) > Pt(IV) >> Cu(II), which ensures selective separation of Rh(III) from their mixture. Adsorption of Rh(III) increases with an increase in the concentration of Sn(II) in the aqueous solution, and maximum adsorption is achieved at a molar ratio, [Sn]/[Rh], of >6. The adsorption of Rh(III) decreases at a high concentration of hydrochloric acid. The maximum adsorption capacity was evaluated to be 0.92 mol/kg-dry adsorbent. Stripping tests of rhodium from the loaded chemically modified chitosan were carried out using different kinds of stripping agents containing some oxidizing agent. The maximum stripping of rhodium under these experimental conditions was found to be 72.5% by a single contact with 0.5 M HCl + 8 M HNO₃.

Keywords: Hydrochloric-Acid Solutions, Metal-Ions

Aksu, Z., Özer, D., Özer, A., Kutsal, T. and Çağlar, A. (1998), Investigation of the column performance of cadmium(II) biosorption by Cladophora crispata flocs in a packed bed. Separation Science and Technology, 33 (5), 667-682.

Full Text: 1998\Sep Sci Tec33, 667.pdf

Abstract: In this study the biosorption of Cadmium(II) ions to dried flocs of Cladophora crispata, a kind of green algae, was investigated in a packed bed column. The Cadmium(II) removal performance of the column was investigated as a function of the Cadmium(II)-bearing solution flow rate and the inlet Cadmium(II) concentration. Removal and total removal percentages of Cadmium(II) related to flow volume were determined by evaluating the breakthrough curves obtained at three different flow rates for two different constant inlet concentrations. At the lowest flow rate the effect of inlet Cadmium(II) concentration on the column capacity was also investigated. Data confirmed that early saturation and lower Cadmium(II) removals were observed at higher flow rates and at higher Cadmium(II) concentrations. Column experiments also showed that maximum specific Cadmium(II) uptake values of C, crispata flocs were as higher as those of other biomass sorbents.

Keywords: Saccharomyces-Cerevisiae, Metal-Cations, Heavy-Metals, Cell-Walls, Biomass, Ions, Vulgaris, Binding, Removal, Packed Bed Column, Flocs of Cladophora crispata, Cadmium(II) Biosorption

Lee, M.Y., Shin, H.J., Lee, S.H., Park, J.M. and Yang, J.W. (1998), Removal of lead in a fixed-bed column packed with activated carbon and crab shell. Separation Science and Technology,