Personal Research Database

Full Text: 2004\Sep Sci Tec39, 1595.pdf

Abstract: Chemical modification of Douglas fir bark and its subsequent utilization in adsorption of Ph²⁺ from aqueous solutions was investigated. We developed a new solvent-free approach to enhance the natural properties of bark by utilizing polyfunctional groups covalently attached at their surface. The hydroxyl groups of their polysaccharide moiety were functionalized by periodate oxidation and derivatized via reductive amination in presence of aspartic acid or 4,4’-diamino-2,2’-stilbene disulfonic acid. The degree of substitution of derivatized bark was estimated by the means of pH titration. Adsorption isotherms of Ph²⁺ on derivatized barks were determined and compared with the performances of crude bark. Adsorption was characterized using the noncompetitive Langmuir adsorption model in terms of affinity (b) and maximum binding capacities (q(max)). Derivatization resulted in enhancements of both q(max) (x 4 - 7) and b (x 1.5 - 10). These experimental data are discussed in the context of the Hard and Soft Acid and Base theory.

Keywords: Adsorption, Adsorption Isotherms, Biosorption, Cellulose, Chemical Modifications, Coniferous Barks, Decontamination, Douglas Fir Bark, Heavy-Metal Ions, Langmuir, Lead, Lignocellulosic, Mechanisms, Recovery, Removal, Sorption, Synthetic Solutions

? Shiau, C.Y. and Pan, C.C. (2004), Adsorption of basic dyes from aqueous solution by various adsorbents. Separation Science and Technology, 39 (8), 1733-1750.

Full Text: 2004\Sep Sci Tec39, 1733.pdf

Abstract: Activated clay, montmorillonite, and activated carbon were used for the removal of two basic dyes, Basic Green 5 (BG5) and Basic Violet 10 (BV10). Both dynamic and equilibrium data were obtained by the batch technique. The dynamic data indicate that the activated carbon was suitable for FIGS but not for BV10 primarily due to the molecular structure, whereas the montmorillonite was not good for either basic dye due to its low surface area for adsorption. The adsorption process was analyzed in terms of two pseudosteady-state equations and the intraparticle diffusion model. The adsorption isotherms of Langmuir and Freundlich as well as Langmuir-Freundlich types were employed to examine the equilibrium adsorption data. Results show that all the adsorption systems could be adequately fitted by the Langmuir-Freundlich equation. Thermodynamic parameters were also obtained.

Keywords: Activated Carbon, Activated Clay, Montmorillonite, Adsorption, Basic Dyes, Activated Carbon, Pore Diffusion, Mass-Transfer, Fly-Ash, Color Removal, Bagasse Pith, Dyestuffs, Sorption, Kinetics, Model

? Mousa, H., Kandah, M. and Abu Al-Rub, F.A. (2004), Removal of copper, lead, and cadmium ions in a fluidized bed. Separation Science and Technology, 39 (8), 1751-1760.

Full Text: 2004\Sep Sci Tec39, 1751.pdf

Abstract: In this study, the recovery of copper from synthetic wastewaters prepared from CUSO₄ was studied using a fluidized bed containing hydrogen-based solid Amberlite. The effects of operating parameters including liquid flow rate, initial copper ions concentration, pH of the influent solution, and Amberlite weight on the breakthrough curves were investigated. It was found that the copper uptake increased with the increase in Amberlite weight, the decrease in initial copper concentration, and decrease in liquid flow rate, but there was no affect with solution influent pH. The recovery of cadmium and lead ions prepared from CdSO₄ and Pb(NO₃)₂, respectively, was also investigated. Comparison between the adsorption of Cu²⁺, Cd²⁺ and Pb²⁺ showed that the adsorption capacity followed the following order: Pb²⁺ > Cd²⁺ > Cu²⁺. It was found that the order of adsorption was independent of the flow rate or the initial feed concentration.

Keywords: Adsorption, Fluidization Waste Water, Industrial Waste, Heavy Metals, Zinc, Exchange, Streams

? Lee, J.W., Shim, W.G., Ko, J.Y. and Moon, H. (2004), Adsorption equilibria, kinetics, and column dynamics of chlorophenols on a nonionic polymeric sorbent, XAD-1600. Separation Science and Technology, 39 (9), 2041-2065.

Full Text: 2004\Sep Sci Tec39, 2041.pdf

Abstract: Adsorption equilibrium, kinetics, and column dynamics of chlorophenols [2-chlorophenol (2-CP) and 2,4-dichlorophenol (2,4-DCP)] dissolved in water were studied using a hydrophobic resin, XAD-1600, without ion-exchange functional groups. In addition, a hydrophilic nonionic polymer resin, XAD-7, and an activated carbon, F400, were chosen for comparative analysis. Adsorption equilibrium data were correlated with the well-known Langmuir, Freundlich, and Sips isotherms. The adsorption amount was in the order of F400 > XAD-1600 > XAD-7. Desorption from polymeric resins adsorbed with chlorophenols was conducted by using two organic solvents [methanol and isopropyl alcohol (IPA)] as desorbates. The intraparticle diffusion mechanism was assumed to be the surface diffusion or pore diffusion. It was found that the diffusivity in desorption step was considerably slower than the diffusivity in adsorption step within polymeric resins. To confirm the possibility of the resin as a sorbent for the removal of chlorophenols, adsorption breakthrough curves were measured under key operating conditions, such as concentration, flow rate, and column length. A simple dynamic model was also formulated to describe both the adsorption and desorption breakthrough curves of chlorophenols.

Keywords: Adsorption, Desorption, Kinetics, Dynamics, Polymeric Sorbent

? Watanabe, Y., Yamada, H., Tanaka, J., Komatsu, Y. and Moriyoshi, Y. (2004), Ammonium ion exchange of synthetic zeolites: The effect of their open-window sizes, pore structures, and cation exchange capacities. Separation Science and Technology, 39 (9), 2091-2104.

Full Text: 2004\Sep Sci Tec39, 2091.pdf

Abstract: Ammonium ion exchange behavior of synthetic zeolites, i.e., sodalite (SOD), rho zeolite (RHO), Linde type A zeolite (LTA), and faujasite zeolite (FAU), was investigated by changing the initial concentration of ammonium ions and reaction time. Ammonium ion exchange behavior was dependent on the open-window sizes, the pore structures, and the cation exchange capacities of these zeolites. Regarding sodalite with Nat ions (Na-SOD), ammonium ion exchange did not completely occur at the equilibrium state because the open-window size is smaller than the diameter of ammonium ions. Regarding RHO with Nat and Cst ions (NaCs-RHO), the larger cations, Cst ion, in the cages obstructed the ion exchange at the initial stage. However, the amount of exchanged ammonium ions gradually increased with increasing reaction time, finally achieving equilibrium. Regarding LTA with Nat ions (Na-LTA), the amount of exchanged ammonium ions decreased with increasing reaction time, and then reached plateau. It indicated that both the ion exchange on the a-cages and physical adsorption on the b-cages occurred at the initial stage, which was followed by the equilibrium state of ion exchange on the a-cages. Regarding FAU with Nat ions (Na-FAU), no dependence on reaction time was observed, because the size of the open-windows is large enough for ion exchange of ammonium ions. The Na-FAU, which has the biggest open-windows among these zeolites, showed the highest exchange capacity for ammonium ions, 3.20 mmol/g.

Keywords: Ammonium, Ion Exchange, Open-Window Size, Pore Structure, Synthetic Zeolite

? Purkait, M.K., Gusain, D.S., Das Gupta, S. and De, S. (2004), Adsorption behavior of chrysoidine dye on activated charcoal and its regeneration characteristics by using different surfactants. Separation Science and Technology, 39 (10), 2419-2440.

Full Text: 2004\Sep Sci Tec39, 2419.pdf

Abstract: Experimental investigations were carried out to adsorb red colored chrysoidine dye from an aqueous medium by using activated charcoal (AC) as an adsorbent. The effects of adsorbent dose, initial dye concentration, contact time, pH, and temperature were studied for the adsorption of chrysoidine under stirred conditions and batch wise. Standard adsorption isotherms were considered to fit the experimental equilibrium data. It was found that the adsorption of chrysoidine on AC follows the Freundlich adsorption isotherm. The rate of adsorption was described by both first- and pseudosecond-order kinetic models. Experimental investigations also were carried out for the regeneration of spent carbon by applying surfactant enhanced carbon regeneration (SECR) technique by using both cationic and anionic surfactant. An empirical kinetic model for regeneration of adsorbent was presented.

Keywords: Chrysoidine, Activated Charcoal, Adsorption Isotherm, Carbon Regeneration, Cationic Surfactant, Anionic Surfactant, Containing Effluents, Waste-Water, Different Bentonites, Color Removal, Azo Dyes, Fly-Ash, Decolorization, Ozonation

? Ana, O.D.S., Jesuino, L.S., Cassella, R.J., Carvalho, M.S. and Santelli, R.E. (2004), Solid-phase extraction of Cd(II) as diethyldithiocarbamate complex by polyurethane foam: Kinetic and thermodynamic characterization. Separation Science and Technology, 39 (11), 2695-2709.

Full Text: 2004\Sep Sci Tec39, 2695.pdf

Abstract: This paper presents a study about the sorption of the cadmium-diethyldithiocarbamate [Cd(II)-DDTC] complex onto polyurethane foam (PUF). It was observed that the maximum sorption of Cd(H) (80 or 150 mug L^-1) was verified at pH 6.8 in the presence of 4.5×10^-5 mol L^-1 DDTC. The shaking time needed to achieve the equilibrium was 40 min. From these data, a kinetic characterization was performed by applying three models, which revealed that a film-diffusion process was a rate-determining mechanism. Results also indicated that an ether-like solvent extraction was the sorption mechanism. The investigation of many metallic ions as concomitants showed that the sorption by foam is relatively selective and it can be enhanced by using a suitable masking agent or incrementing the foam mass.

Keywords: Solid-Phase Extraction, Polyurethane Foam, Diethyldithiocarbamate, Cadmium, Trace-Element Preconcentration, Universal Matrix, Organic Reagents, Metal-Ions, Sorption, Separation, Silver, Cobalt, Collection, Adsorption

? Cortés-Martínez, R., Martínez-Miranda, V., Solache-Ríos, M. and García-Sosa, I. (2004), Evaluation of natural and surfactant-modified zeolites in the removal of cadmium from aqueous solutions. Separation Science and Technology, 39 (11), 2711-2730.

Full Text: 2004\Sep Sci Tec39, 2711.pdf

Abstract: The present study involves an investigation on the comparison of a Mexican clinoptilolite-heulandite zeolitic mineral and the modified zeolitic material with the surfactant hexadecyltrimethylammonium bromide (HDTMA) for the removal of cadmium from aqueous solutions. The effects of pH and contact time on the adsorption process were examined. The optimum pH for adsorption was found to be 7. Cadmium retention reached equilibrium in 32 h and the rate of cadmium adsorption by the zeolites was rapid in the first 10 h. Elovich’s model best described the reaction rate. Batch adsorption experiments conducted at room temperature showed that the adsorption pattern followed the Langmuir-Freundlich isotherm model. The cadmium retention capacity decreased very slightly when the zeolite surface was modified with the surfactant HDTMA, and this material has advantages for its use in the removal of some other contaminants, such as anions and nonpolar organic compounds, like phenols. The results showed that natural zeolite and the surfactant modified zeolite could be considered as potential adsorbents for cadmium removal from aqueous solutions.

Keywords: Clinoptilolite, Ion Exchange, Cadmium, Adsorption, HDTMA, Ion-Exchange, Sorption, Kinetics, Clinoptilolite, Effluents, Chromate, Metals, Peat

? Santhy, K. and Selvapathy, P. (2004), Removal of heavy metals from wastewater by adsorption on coir pith activated carbon. Separation Science and Technology, 39 (14), 3331-3351.

Full Text: 2004\Sep Sci Tec39, 3331.pdf

Abstract: The activated carbon prepared from coconut coir pith by potassium hydroxide activation was found to exhibit remarkable adsorption capacity for cadmium, copper, and zinc. Batch equilibrium tests showed that the extent of metal removal was found to be dependent on initial concentration, contact time, pH, and carbon dose. It was found that at pH values below 3, the adsorption of metal ions was very less and was effective above pH 6. The metal ion sorption was found to follow the Freundlich model. The kinetics of adsorption of metal ions followed 1st order. The agglomerated coir pith carbon was evaluated for the effect of flow rate and bed depth in column experiments. Linear relationships between bed depth and service time were obtained for all the metal ions by performing bed-depth service time (BDST) analysis. The adsorbed metal ions could be quantitatively recovered by using 1.0 M HCl, and the capacity of carbon remained unaffected when put to repeated use for the removal of metal ions from aqueous solutions. The efficiency of carbon when applied to industrial effluents was found to be superior in removal of metal ions compared with the commercial ones.

Keywords: Coir Pith, Activated Carbon, Heavy Metals, Adsorption, Batch Studies, Freundlich Isotherm, Kinetics, Column Studies, BDST, Effluent Treatment, Equilibrium, Cadmium

? Hasany, S.M. and Ahmad, R. (2004), Removal of traces of silver ions from aqueous solutions using coconut husk as a sorbent. Separation Science and Technology, 39 (15), 3509-3525.

Full Text: 2004\Sep Sci Tec39, 3509.pdf

Abstract: Sorption of silver ions onto coconut (Cocos nucifera) husk has been studied in detail using radiotracer technique. Maximum sorption (98%) of Ag ions (8.2310^-4 M) onto sorbent surface is achieved from 4.5 mL of 0.1 M HNO₃ solution within 20 min using 200 mg of coconut husk. The sorption data follow the Freundlich and Dubinin-Radushkevich (D-R) isotherms. The values of Freundlich characteristic constants 1/n = 0.98  0.09 and of A(m) 0.35  0.05 m mole g^-1 and D-R constants beta = -0.006207  0.000439 kJ² mole^-2, X_m = 0.57  0.08 m mole g^-1, and E = 9.00.3 kJ mole^-1 have been computed. The variation of sorption with temperature yields thermodynamic parameters eters DeltaH = 61.35.4 k J mole^-1, DeltaS = 241.918.7 J mol^-1 K^-1, and DeltaG = -10.6  0.09 k J mole^-1 at 298 K. The positive enthalpy and negative value of free energy reflect the endothermic and spontaneous nature of sorption respectively. Sulphate, Al(III), Ni(II), and Ba(II) enhance the sorption significantly whereas Ce(III) and citrate cause its suppression appreciably. To check the selectivity of the coconut husk, the sorption of a number of metal ions on the sorbent surface has been measured under optimized conditions. The results indicate that coconut husk can be used to separate Ag ions from Cs(I), Zn(II), Cr(III), Co(II), and Se(IV).

Keywords: Ag(I) Ions, Sorption, Radiotracer Technique, Thermodynamics, Sorption Isotherms, Coconut Husk, Hg(II) Ions, Sorption, Radiotracer, Bark, Adsorption, Behavior, Binding

? Minato, J., Kim, Y.J., Yamada, H., Watanabe, Y., Tamura, K., Yokoyama, S., Cho, S.B., Komatsu, Y. and Stevens, G.W. (2004), Alkali-hydrothermal modification of air-classified Korean natural zeolite and their ammonium adsorption behaviors. Separation Science and Technology, 39 (16), 3739-3751.

Full Text: 2004\Sep Sci Tec39, 3739.pdf

Abstract: Korean natural zeolite in which clinoptilolite and mordenite coexisted with feldspar and illite as impurities, was treated with 1.0, 3.0, and 5.0 M NaOH solutions at 100, 150, and 200degreesC under autogeneous pressure for 17 hours either with or without an air classification as pretreatment. Phillipsite, analcime, and hydroxycancrinite were identified as reaction products depending on the reaction temperature and NaOH concentration. The air classification of the starting material prior to alkali-hydrothermal treatment effectively reduced the amount of feldspar, which hardly reacted to zeolite in the hydrothermal reaction. The ammonium adsorption behavior of the treated and untreated samples were investigated in solutions of between 10^-3 M and 10^-2 M NH₄Cl. The amount of adsorbed ammonium ions in alkalihydrothermally treated product from air-classified material was higher by about two times than was that of corresponding untreated zeolites. The air-classified zeolite treated in 3 M NaOH solution at 100degreesC showed the highest adsorption of ammonium ion among samples. It was explained by both the phase change of clinoptilolite and mordenite to phillipsite with higher cation exchange capacity and the reduction in the amount of feldspar that was less reactive under hydrothermal conditions for the formation of phillipsite. The results indicated that the combination of the air classification and alkali-hydrothermal treatment effectively improved the adsorption behavior for ammonium ions on natural zeolites with impurities.

Keywords: Adsorption, Air, Air Classification, Alkali-Hydrothermal Treatment, Ammonium, Australian Zeolite, Behavior, Capacity, Cation Exchange Capacity, Classification, Clinoptilolite, Concentration, Ion, Korean Natural Zeolite, Modification, Mordenite, Natural, Pressure, Products, Reaction, Reduction, Removal, Temperature, Treatment, Zeolite

? Coutinho, M.R., Quadri, M.B., Moreira, R.F.P.M. and Quadri, M.G.N. (2004), Partial purification of anthocyanins from Brassica oleracea (red cabbage). Separation Science and Technology, 39 (16), 3769-3782.

Full Text: 2004\Sep Sci Tec39, 3769.pdf

Abstract: Red cabbage has a high content of anthocyanin and it may become an important source of this pigment. Common extraction methods are not selective, and a great quantity of sugar is co-extracted with the dye. This work used adsorption-desorption process on Amberlite XAD7 and Sephadex LH20 resins to partially purify anthocyanins present in the whole juice of red cabbage. Both resins succeeded to purify anthocyanins, producing solutions with up to 0.5 g L^-1 of sugars from an initial concentration of more than 25 g L^-1. Using Amberlite XAD7 it was possible to recover 24 to 95% of the dye initially found in the whole juice while 11 to 56% was recovered using Sephadex LH20. The kinetics of adsorption of the dye on Amberlite XAD7 was described according to a pseudo-second-order model, and the sorption equilibrium was well described by the Freundlich isotherm. The adsorption enthalpy was -17.13 kcal mol^-1, indicating a possible chemical adsorption.

Keywords: Anthocyanin, Purification, Sorption, Red Cabbage, Kinetics, Stability, Sorption, Potato, Peat

? Kasaini, H., Everson, R.C. and Bruinsma, O.S.L. (2005), Selective adsorption of platinum from mixed solutions containing base metals using chemically modified activated carbons. Separation Science and Technology, 40 (1-3), 507-523.

Full Text: 2005\Sep Sci Tec40, 507.pdf

Abstract: Bituminous coal was activated by using steam at 750degreesC in a furnace. The activated carbon (AC) particles were chemically treated with thiophosphoric and amine type extractants, then characterized and tested for precious metal selectivity in chloride media. The adsorption of anions [PtCl₄^3-, PdCl₄^2-] or cations [PtCl⁺, PdCl(H₂O)³⁺, Ni(H₂O)⁺, Cu²⁺]on the carbon surface was elucidated by means of complexation and physical adsorption models. Owing to electrostatic repulsion in acidic media (>1 M HCl), the thio- and amine-treated bituminous ACs did not react with copper and nickel cations. The adsorption rate constant for platinum showed a dependence on solution pH and extractant dosage on the surface of the carbon and was of the order 10^-2 min^-1. A three-parameter Toth isotherm best described the adsorption data for single component solutions. Furthermore, platinum adsorption was described by pseudo first order kinetics neglecting the intraparticle diffusivity.

Keywords: Activated Carbon, Adsorption, Adsorption Rate, Amine, Carbon, Chloride, Coal, Complexation, Copper, Dependence, Didodecylmonothiophosphoric Acid, Dosage, HCl, Isotherm, Kinetics, Metals, Model, Models, Modified, Nickel, Palladium, Particles, Pd(II), Pellets, pH, Physical Adsorption, Platinum, Rate Constant, Rh(III), Selectivity, Separation, Solvent-Extraction, Surface

? Loukidon, M.X., Karapantsios, T.D., Zouboulis, A.I. and Matis, K.A. (2005), Cadmium(II) biosorption by Aeromonas caviae: Kinetic modeling. Separation Science and Technology, 40 (6), 1293-1311.

Full Text: 2005\Sep Sci Tec40, 1293.pdf

Abstract: Biosorption of cadmium from aqueous solutions on Aeromonas caviae particles was investigated in a well-stirred batch reactor. Equilibrium and kinetic experiments were performed at various initial bulk concentrations, biomass loads, temperatures, and ionic background. Equilibrium data were well described by typical Langmuir and Freundlich adsorption isotherms. Furthermore, a detailed analysis was conducted to test several chemical reaction kinetic models in order to identify a suitable kinetic equation, assuming that biosorption is chemical sorption controlled. Predictions based on the so-called pseudo second order rate expression were found in satisfactory accordance with experimental data.

Keywords: Biosorption, Cadmium(II), Equilibrium Study, Kinetic Study, Metals, Heavy-Metals, Aqueous-Solutions, Biomass, Equilibrium, Removal, Ions, Biosorbents, Effluents, Recovery, Bacteria

? Griffith, C.S., Luca, V., Yee, P. and Šebesta, F. (2005), Separation of cesium and strontium from acidic radioactive waste simulants using a microporous tungstate/polyacrylonitrile (PAN) composite adsorbent. Separation Science and Technology, 40 (9), 1781-1796.

Full Text: 2005\Sep Sci Tec40, 1781.pdf

Abstract: The inorganic phase, Na0.2Mo0.03W0.97O3 - ZH(2)O (MoHTB), which has been previously shown to be selective for Cs⁺ and Sr²⁺ from acidic radwaste simulants (0.075 mmol - L^-1, 1.0 M HNO₃) has been granulated with polyacrylonitrile (PAN) to afford a composite adsorbent suitable for deployment in small scale, fixed-bed columns. The uptake of Cs⁺ and Sr²⁺ by the MoHTB-PAN composites from such an acidic radwaste simulant is optimal for granular material of mesh size < 0.3 mm but satisfactory uptake rates are also observed with material of mesh size 0.3-0.63 turn. The fixed-bed column adsorption of Cs⁺ and Sr²⁺ from acidic radwaste simulant affords breakthrough curves which are of a typical ‘S’ shape profile but desorption of adsorbed Sr²⁺ by Cs⁺ in the radwaste simulant occurs after the composite column achieves equilibrium with respect to Sr²⁺. A simplified model of the adsorption of Cs⁺ and Sr²⁺ by the MoHTBPAN composite fixed-bed column has been applied to these initial results and has been shown to have utility in describing the performance of the fixed-bed column setup at the equimolar concentrations of Cs⁺ and Sr²⁺ employed.

Keywords: Ion-Exchange, Radwaste, Cesium, Strontium, Composite Adsorbent, Fixed-Bed Adsorption, Ion-Exchange Properties, Titanosilicate, Tungstates

? Ghazy, S.E., Samra, S.E., Mahdy, A.M. and El-Morsey, S.M. (2005), Kinetic investigation of the removal of aluminum from water samples by adsorption onto powdered marble wastes. Separation Science and Technology,