Personal Research Database

Full Text: 2006\Sep Pur Tec50, 1.pdf

Abstract: Experiments were conducted to investigate the adsorption characteristics of dyes by anaerobic sludge in this study. Influence of dye type, sorption time, initial dye concentration, sludge concentration and temperature on dye biosorption was evaluated. Furthermore, the isotherms, kinetics and thermodynamic of biosorption were also explored. Experimental results show that anaerobic sludge had a much higher equilibrium adsorption density on Rhodamine B than on Eosin Y. The adsorption density of Rhodamine B onto sludge decreased with enhancing sludge concentration. At a lower Rhodamine B concentration, adsorption could reach saturation in a lower sludge concentration. Results also indicate that both Langmuir and Freundlich adsorption models were able to adequately describe the biosorption equilibrium of Rhodamine B onto anaerobic sludge. The biosorption followed the pseudo second-order adsorption kinetics.

Keywords: Anaerobic Sludge, Biosorption, Dye, Eosin Y, Freundlich Model, Kinetics, Langmuir Model, Rhodamine B, Thermodynamics

? Chen, C.Y., Chiang, C.L. and Huang, P.C. (2006), Adsorptions of heavy metal ions by a magnetic chelating resin containing hydroxy and iminodiacetate groups. Separation and Purification Technology, 50 (1), 15-21.

Full Text: 2006\Sep Pur Tec50, 15.pdf

Abstract: A magnetic Fe₃O₄–glycidyl methacrylate–iminodiacetic acid–styrene–divinyl benzene resin (MPGI) was synthesized by the polymerization of glycidyl methacrylate–iminodiacetic acid (GMA–IDA), divinyl benzene and styrene in the presence of magnetic Fe₃O₄ for the removal of Cu(II), Cd(II) and Pb(II) from aqueous solutions. The weight fractions of Fe₃O₄ and GMA–IDA within MPGI were analyzed by potentiometric titration of carboxylic acids and thermogravimetric analyzer. The equilibrium adsorption capacities of MPGI from their single-metal ion solutions were 0.88 mmol/g for Cu(II), 0.81 mmol/g for Pb(II) and 0.78 mmol/g for Cd(II). Increasing the concentration (0–0.3 M) of KCl, NaCl, MgCl₂ and CaCl₂ in Cu(II) or Pb(II) solution affected the adsorption behavior slightly. As the salt concentrations in Cd(II) solution increased, the adsorption capacities of Cd(II) decreased in the order: Mg²⁺ > Ca²⁺ > Na⁺ > K⁺. Within the pH range of 2–5, decreasing the pH of the Cu(II) solution did not produce remarkable changes in the equilibrium adsorption capacities. However, significant decrements occurred for the adsorptions of Pb(II) or Cd(II) when the pH values of the solutions were less than 3. The competitive adsorption tests verified that this resin had good adsorption selectivity for Cu(II) with the coexistence of Pb(II) and Cd(II).

Keywords: Resin, Adsorption, Competitive Adsorption, Selectivity, Iminodiacetic Acid

? Kurtoğlu, A.E. and Atun, G. (2006), Determination of kinetics and equilibrium of Pb/Na exchange on clinoptilolite. Separation and Purification Technology, 50 (1), 62-70.

Full Text: 2006\Sep Pur Tec50, 62.pdf

Abstract: Ion exchange kinetics and equilibria of lead on Na-pretreated clynoptilolite have been studied using batch method by means of electrometric and polarographic techniques. Equivalent fraction of lead ions exchanged with sodium has been determined by measuring time dependent Na⁺ ion concentration with sodium ion selective electrode (SISE). Electrode readings could be taken for a time interval of 15 s at early time of exchange. Time dependence of pH during exchange process has been followed simultaneously. Time dependent exchange curves showed a sharp increase at the beginning followed by a slower one for longer times until reaching equilibrium. The McKay equation for isotopic exchange kinetics has been applied to describe experimental results both in terms of out- and in-going ions. The film and particle diffusion coefficients evaluated from the McKay constants are not significantly affected by initial solution concentrations studied in the range of 110^-4 to 110^-4 M. Kinetic curves have been successfully modeled using the diffusion coefficients. An increase in the pH values at low concentrations below 10^-3 M Pb can be attributed to contribution of H⁺/Na⁺ exchange whereas the decrease of pH is indicative of the uptake of hydroxyl ions to form lead hydroxide clusters into clinoptilolite at higher concentrations. Total amount of Pb adsorbed and exchanged at equilibrium condition has been determined from polarographic measurements and compared with those found for exchanged Pb. Equilibrium data have been analyzed and modeled in terms of Freundlich and Langnmir adsorption isotherms. Thermodynamic parameters for transition state have been evaluated from temperature dependent kinetic results. (C) 2005 Elsevier B.V. All rights reserved.

Keywords: Ion Exchange Kinetics, Lead, Clinoptilolite, Ion Selective Electrodes, Polarographic Measurement, Ion-Exchange, Natural Clinoptilolite, Isotopic-Exchange, Aqueous-Solutions, Modified Zeolites, Calcium-Ion, Removal, Pb²⁺, Lead, Isotherms

? Fiol, N., Villaescusa, I., Martínez, M., Miralles, N., Poch, J. and Serarols, J. (2006), Sorption of Pb(II), Ni(II), Cu(II) and Cd(II) from aqueous solution by olive stone waste. Separation and Purification Technology, 50 (1), 132-140.

Full Text: 2006\Sep Pur Tec50, 132.pdf

Abstract: Olive stone waste generated in the olive oil production process has been investigated as metal biosorbent for Pb(II), Ni(II), Cu(II) and Cd(II) from aqueous solutions for its wide availability as agricultural waste and also for its cellulosic matrix rich of potential metal binding active sites. The effect of contact time, solution pH, ionic medium and initial metal concentration were studied in batch experiments at room temperature. Maximum metal sorption was found to occur at initial pH around 5.5–6.0. Kinetic studies revealed that the initial uptake was rapid and equilibrium was established in 1 h for all the studied metals and that the data followed the pseudo-second order reaction. The equilibrium sorption data for single metal systems at initial pH 5.5 were described by the Langmuir and Freundlich isotherm models, however, the non-competitive Freundlich model has been found to provide the best correlation. The highest value of Langmuir maximum uptake, (q_max), was found for cadmium (6.88×10⁻⁵ mol g⁻¹) followed by lead (4.47×10−5 mol g⁻¹), nickel (3.63×10⁻⁵ mol g⁻¹) and copper (3.19×10⁻⁵ mol g⁻¹). Similar Freundlich empirical constants, k, were obtained for all metals (2.4×10⁻⁵ to 2.8×10⁻⁵). Adsorption-complexation, in addition to ion-exchange, must be involved in the sorption process of copper, lead and cadmium while ion-exchange is the most important mechanism for Ni sorption. An increase of ionic strength concentration caused a decrease in metal removal. Sorption experiments with equimolar concentration of each metal in binary mixtures were also performed and then the extended Langmuir isotherm model fits adequately the experimental data. Desorption experiments put into evidence that after three contacts neither HCl nor EDTA solutions were able to desorb metals from the olive stones completely. The results obtained show that olive stone waste, which has a very low economical value, may be used for the treatment of wastewaters contaminated with heavy metals.

Keywords: Metal Removal, Low Cost Sorbent, Biosorption, Sorption Isotherms, Binary Mixtures

? Bayramoğlu, G., Senel, A.U. and Arica, M.Y. (2006), Effect of spacer-arm and Cu(II) ions on performance of l-histidine immobilized on poly(GMA/MMA) beads as an affinity ligand for separation and purification of IgG. Separation and Purification Technology, 50 (2), 229-239.

Full Text: 2006\Sep Pur Tec50, 229.pdf

Abstract: In this study, the beads were prepared from glycidiyl methacrylate (GMA) and methyl methacrylate (MMA) via suspension polymerization and, the used beads fractions were between 75 and 150 μm. The epoxy groups of the beads were converted into amino groups by the reaction of ammonia or 1,6-diaminohexane as a spacer-arm. l-Histidine ligand was immobilized onto both beads. Cu(II) ions were chelated onto spacer-arm attached and l-histidine immobilized beads. The IgG adsorption capacity of the spacer-arm attached and Cu(II) chelated affinity beads led to higher adsorption capacities about 1.64- and 2.94-fold, respectively. The adsorption equilibrium studies showed that the adsorption isotherm of IgG obeyed the Langmuir isotherm model. The experimental data was well described by the second-order equations. Purification data of IgG with spacer-arm attached and Cu(II) ions chelated (i.e. poly(GMA/MMA)-SAH-Cu(II)) beads indicated that 87.5% of IgG was removed from human serum with a purity of 90%.

Keywords: Affinity Beads, Histidine, IgG, Adsorption, Purification, Thermodynamic Parameters

? Adak, A. and Pal, A. (2006), Removal of phenol from aquatic environment by SDS-modified alumina: Batch and fixed bed studies. Separation and Purification Technology, 50 (2), 256-262.

Full Text: 2006\Sep Pur Tec50, 262.pdf

Abstract: Alumina is a very efficient adsorbent for the removal of anionic surfactant (AS) from aqueous environment even when it is present at a very high concentration. After removal of AS the exhausted surfactant coated alumina hereafter designated as surfactant-modified alumina (SMA) posses the ability to remove organic solutes from aquatic environment through the process called adsolubilization. In this study, SMA was used for the removal of phenol from water environment. In batch study it was seen that the pH < 7 favours the removal. The removal efficiency was increased in the presence of anions and decreased a little in the presence of cations. Temperature had no effect on the removal of phenol. The column having a diameter of 2 cm, with different bed heights such as 10, 20 and 30 cm could treat 1.65, 3.66 and 5.27 l of phenol bearing wastewater with initial phenol concentration 50 mg/l and flow rate 8.5 ml/min. Time required for the bed to become exhausted after the breakthrough occurred was very short. This indicated that the adsorption zone was almost saturated at the time of exhaustion. Different column design parameters like depth of exchange zone, time required for exchange zone to move its own height, adsorption rate, adsorption capacity, etc., were calculated. Theoretical breakthrough curve was drawn from the batch isotherm data and it was compared with experimental breakthrough curve. Desorption of phenol from the SMA surface was possible using 0.25M sodium hydroxide solution, rectified spirit and acetone.

Keywords: Alumina, Sodium Dodecyl Sulfate, Surfactant-Modified Alumina, Phenol, Adsorption, Column Study, Breakthrough Curve

? Ye, H.P., Chen, F.Z., Sheng, Y.Q., Sheng, G.Y. and Fu, J.M. (2006), Adsorption of phosphate from aqueous solution onto modified palygorskites. Separation and Purification Technology, 50 (3), 283-290.

Full Text: 2006\Sep Pur Tec50, 283.pdf

Abstract: In this study, the natural and modified palygorskites were tested to remove phosphate ions from aqueous solution. The modified palygorskites were prepared by being activated with hydrochloric acid and/or thermal treatments. The surface structure of the materials was investigated by means of X-ray diffraction (XRD), a N₂ adsorption–desorption technique and Fourier transform-infrared (FT-IR) to understand the effect of surface properties on the adsorption behavior of phosphate. In the adsorption test, the adsorption isotherms, kinetics, pH effect, desorbability and selectivity were examined. The results showed that the modified palygorskites had faster kinetics and higher adsorption capacities than the natural palygorskite, which can be attributed to the surface structural changes of the materials, and the adsorbed amounts of phosphate tend to decrease with the increase of pH for all samples. The desorbability of P is about 10–13%, and it is relatively difficult for the adsorbed PO₄³⁻ to be desorbed. Palygorskite could selectively adsorbed phosphate in complex solutions, and the selectivity of phosphate adsorption onto palygorskites was 1000–3000 times that of chloride. The relatively low cost and high capabilities of the natural and modified palygorskites make them potentially attractive adsorbents for the removal of phosphate from aqueous solution.

Keywords: Acid Activation, Adsorbents, Adsorption, Adsorption Capacity, Adsorption Isotherms, Adsorption-Desorption, Behavior, Chloride, Complex, Cost, FT-IR, FTIR, Hydrochloric Acid, Isotherms, Kinetics, Materials, Modified, Natural, Palygorskite, pH, Phosphate, Phosphate Adsorption, Phosphorus, Properties, Removal, Selectivity, Structure, Surface, Surface Properties, Surface Structure, Waste-Water, X-Ray Diffraction, XRD

? Tripathy, S.S., Bersillon, J.L. and Gopal, K. (2006), Removal of fluoride from drinking water by adsorption onto alum-impregnated activated alumina. Separation and Purification Technology, 50 (3), 310-317.

Full Text: 2006\Sep Pur Tec50, 310.pdf

Abstract: The ability of the alum-impregnated activated alumina (AIAA) for removal of fluoride from water through adsorption has been investigated in the present study. All the experiments are carried out by batch mode. The effect of various parameters viz. contact time, pH effect (pH 2–8), adsorbent dose (0.5–16 g/l), initial fluoride concentration (1–35 mg/l) has been investigated to determine the adsorption capacity of AIAA. The adsorbent dose and isotherm data are correlated to the Bradley equation. The efficacy of AIAA to remove fluoride from water is found to be 99% at pH 6.5, contact time for 3 h, dose of 8 g/l, when 20 mg/l of fluoride is present in 50 ml of water. Energy-dispersive analysis of X-ray shows that the uptake of fluoride at the AIAA/water interface is due to only surface precipitation. The desorption study reveals that this adsorbent can be regenerated following a simple base–acid rinsing procedure, however, again impregnation of the regenerated adsorbent (rinsed residue) is needed for further defluoridation process.

Keywords: Fluoride, Impregnation, Activated Alumina, Adsorption, EDAX, Desorption

? Verma, A., Chakraborty, S. and Basu, J.K. (2006), Adsorption study of hexavalent chromium using tamarind hull-based adsorbents. Separation and Purification Technology, 50 (3), 336-341.

Full Text: 2006\Sep Pur Tec50, 336.pdf

Abstract: The adsorption characteristics of hexavalent chromium was studied with an adsorbent developed from waste tamarind hull. Experiments were conducted in batch mode to observe the influence of different parameters such as initial concentration of metal ions, adsorbent dosage, adsorbent particle size, stirrer speed, temperature and pH of the solution. Acidic pH strongly favored the adsorption. With decreasing the pH of the solution from 5.0 to 1.0, the removal of chromium was enhanced from 33% to 99%. The adsorption process was found to follow a pseudo-first-order rate mechanism and the rate constant was evaluated at 30 °C. The Freundlich, Redlich–Peterson and the Fritz–Schlunder isotherm fit the equilibrium data satisfactorily. Adsorption of chromium was found to increase with increase in the process temperature. Using an adsorbent dosage of 1.0 g/L and an acidic pH (2.0), the equilibrium adsorption capacity of the prepared adsorbent was found to be about 70 mg/g at 30 °C, which increased to about 81 mg/g at 50 °C. The entropy change, free energy change and heats of adsorption were determined for the process.

Keywords: Hexavalent Chromium, Tamarind Hull, Adsorption Isotherm, Thermodynamic Parameters, pH Effect, Rate Constant

? Kaušpėdienė, D. and Snukiškis, J. (2006), Sorption kinetics of ammonia and ammonium ions on gel and macroporous sulphonic acid cation exchangers. Separation and Purification Technology, 50 (3), 347-353.

Full Text: 2006\Sep Pur Tec50, 347.pdf

Abstract: Diffusion of ammonia and ammonium ions in sulphonic acid cation exchangers (gel Purolite SGC 100×10 MBH and macroporous Purolite C 160 MBH) from the solutions, representing the composition of ‘caustic condensate’ (waste of nitrogen fertilizers production) is affected by pH of initial solution and structure of the matrix of cation exchanger. In gel matrix the effective intraparticle diffusivity (D_ef) depends greatly on the solution pH because of shrinkage in alkaline and swelling in acidic medium: on decreasing the initial concentration of ammonia from 0.214 to 0.003 and increasing that of ammonium nitrate from 0 to 0.214 mol l⁻¹ instead, the effect of ion exchange leads to a decrease in pH, resulting in swelling and increase in D_ef from 0.1 to 0.34×10⁻¹⁰ for gel Purolite SGC 100×10 MBH and variation of 0.18–0.11×10⁻¹⁰ m² s⁻¹ for macroporous Purolite C 160 MBH (resistant to shrinkage and swelling).

In Purolite C 160 MBH both macropore diffusivity (0.07–0.29×10⁻¹⁰ m² s⁻¹) and gel (solid phase) diffusivity (0.06–0.19×10⁻¹⁰ m² s⁻¹) are higher than micropore diffusivity (0.28–0.56×10⁻¹⁸ m² s⁻¹).

With respect to the effective intraparticle diffusivity, resistance to nitric acid, used for the regeneration, and high concentration of ammonium nitrate in eluate (up to 110 g l⁻¹), Purolite C 160 MBH has been installed for the conversion of ammonia and ammonium ions to ammonium nitrate reusable in the fertilizers production. This allows minimizing the economic loss and preventing the environmental contamination.

Keywords: Cation Exchangers, Ammonium Recovery, Caustic Condensate, Fertilizers Production

? Han, Y.H., Quan, X., Chen, S., Zhao, H.M., Cui, C. and Zhao, Y.Z. (2006), Electrochemically enhanced adsorption of aniline on activated carbon fibers. Separation and Purification Technology, 50 (3), 365-372.

Full Text: 2006\Sep Pur Tec50, 365.pdf

Abstract: For adsorptive separation processes, the adsorption rate and capacity are two important factors affecting the costs. This study describes the anodic polarization of activated carbon fibers (ACFs), which can enhance the adsorption rate and capacity of aniline. The electrosorption kinetics and the affecting factors (bias potential, electrolyte, and pH) of isotherms for aniline on ACFs were investigated. The adsorption/electrosorption of aniline on ACFs follow pseudo-first-order adsorption kinetics, and the adsorption rate improves with increasing bias potential. The electrosorption isotherms, which exhibit a variety of responses depending on bias potential, electrolyte and pH, follow the two classical models of Langmuir and Freundlich. With electrosorption of aniline from aqueous solution, a two-fold enhancement of adsorption capacity is achievable. The initial and saturated ACFs were characterized using scanning electron micrograph (SEM) and Fourier transform infrared spectroscopy (FT-IR). The SEM micrographs show that the surface of ACFs is not oxidized, which is also verified by cyclic voltammetry results. The FT-IR spectroscopy suggests that the interaction between aniline and ACFs is main weak physisorption instead of chemisorption. These experimental results suggest that the electrochemical polarization of ACFs can effectively improve the adsorption rate and capacity of aniline, which may be due to the enhanced affinity between aniline and ACFs instead of the oxidation on the surface of ACFs or in the solution.

Keywords: Activated Carbon Fibers, Aniline, Electrosorption, Adsorption Kinetics, Adsorption Isotherms

? Bhattacharyya, K.G. and Sen Gupta, S. (2006), Kaolinite, montmorillonite, and their modified derivatives as adsorbents for removal of Cu(II) from aqueous solution. Separation and Purification Technology, 50 (3), 388-397.

Full Text: 2006\Sep Pur Tec50, 388.pdf

Abstract: Adsorption of metals by clay minerals is a complex process controlled by a number of environmental variables. The present work investigates the removal of Cu(II) ions from an aqueous solution by kaolinite, montmorillonite, and their poly(oxo zirconium) and tetrabutylammonium derivatives. The entry of ZrO and TBA into the layers of both kaolinite and montmorillonite was confirmed by XRD measurement. The specific surface areas of kaolinite, ZrO-kaolinite, TBA-kaolinite, montmorillonite, ZrO-montmorillonite, TBA-montmorillonite were 3.8, 13.4, 14.0, 19.8, 35.8 and 42.2 m²/g, respectively. The cation exchange capacity (CEC) was measured as 11.3, 10.2, 3.9, 153.0, 73.2 and 47.6 meq/100 g for kaolinite, ZrO-kaolinite, TBA-kaolinite, montmorillonite, ZrO-montmorillonite, TBA-montmorillonite, respectively. Adsorption increased with pH till Cu(II) ions became insoluble in alkaline medium. The kinetics of the interactions suggests that the interactions could be best represented by a mechanism based on second order kinetics (k₂ = 7.7×10⁻² to 15.4×10⁻² g mg⁻¹ min⁻¹). The adsorption followed Langmuir isotherm model with monolayer adsorption capacity of 3.0–28.8 mg g⁻¹. The process was endothermic with ΔH in the range 29.2–50.7 kJ mol⁻¹ accompanied by increase in entropy and decrease in Gibbs energy. The results have shown that kaolinite, montmorillonite and their poly(oxo zirconium) and tetrabutyl-ammonium derivatives could be used as adsorbents for separation of Cu(II) from aqueous solution.

Keywords: Adsorption, Adsorption Isotherm, Copper, Cu(II), Gas-Adsorption, Heavy-Metal Removal, Ions, Isotherm, Kaolinite, Kinetics, Kinetics, Langmuir Isotherm Model, Model, Montmorillonite, Pillared Clays, Poly(Oxo Zirconium) Clay, Removal, Second-Order, Silica, Sorption, Tetrabutyl-Ammonium Clay, Tree Fern, Water

? Kundu, S. and Gupta, A.K. (2006), Adsorptive removal of As(III) from aqueous solution using iron oxide coated cement (IOCC): Evaluation of kinetic, equilibrium and thermodynamic models. Separation and Purification Technology, 51 (2), 165-172.

Full Text: 2006\Sep Pur Tec51, 165.pdf

Abstract: The ability of iron oxide coated cement (IOCC) to remove As(III) by sorption from solution was assessed. Batch experiments were conducted to characterize the As(III) removal capacity of IOCC. The effects of process parameters such as pH (3.2–12), agitation speed (50–250 rpm), contact time, initial As(III) concentration (0.7–13.5 mg l⁻¹) and background ions (Ca²⁺, Mg²⁺, Fe³⁺, SO₄²⁻, PO₄³⁻, Cl⁻ and NO₃⁻) on As(III) uptake were investigated. The adsorption kinetics study at 303 K revealed that the uptake of As(III) ion was very rapid and most of fixation occurred within the first 20 min of contact and pseudo-second order rate equation was able to provide realistic description of adsorption kinetics. Linear regression analysis showed that the equilibrium data of As(III) adsorption at different initial As(III) concentrations and adsorbent dose of 30 g l⁻¹, obeyed the Langmuir isotherm model with maximum sorption capacities of 0.73, 0.69, 0.67 and 0.66 mg g⁻¹ of As(III) on IOCC at 288, 298, 308 and 318 K, respectively. Non-linear error analysis showed that Freundlich isotherm best-fits the equilibrium data for As(III) adsorption onto IOCC. Evaluation of the thermodynamic parameters ΔH°, ΔS° and ΔG° indicated a spontaneous and exothermic nature of adsorption. The presence of co-existing ions such as Ca²⁺, Mg²⁺, Fe³⁺, SO₄²⁻, PO₄³⁻, Cl⁻ and NO₃⁻ had no noticeable effect on As(III) removal showing excellent As(III) sequestering capability of IOCC. The adsorbent was also suitable for repeated use (for three cycles) without noticeable loss of capacity.

Keywords: Adsorption, Arsenic, Kinetics, Isotherm, Equilibrium

? Erdem, M. and Ozverdi, A. (2006), Kinetics and thermodynamics of Cd(II) adsorption onto pyrite and synthetic iron sulphide. Separation and Purification Technology,