Personal Research Database

Full Text: S\Sep Sci Tec36, 241.pdf

Abstract: The kinetics of sorption of lead ion are described by a pseudo-second-order model modified with a new parameter, t₀, included to account for an initial resistance due to the film boundary layer. Analysis of this model has been carried out at various experimental conditions to study the effect of initial lead ion concentration, peat particle size, solution temperature, and agitation speed in an agitated batch system. The pseudo-second-order rate constant, initial sorption rate, and sorption capacity, together with time constant, t₀, also have been determined and correlated as a function of the system variables.

Keywords: Activated Carbon, Adsorption, Aqueous-Solutions, Batch System, Capacity, Dyestuffs, Intraparticle Diffusion-Processes, Ion-Exchange, Kinetics, Lead, Mass-Transfer Processes, Peat, Pseudo Second Order, Second Order, Soil Organic-Matter, Sorption, Sphagnum Moss Peat, Transport

Zouboulis, A.I., Matis, K.A. and Lazaridis, N.K. (2001), Removal of metal ions from simulated wastewater by Saccharomyces yeast biomass: Combining biosorption and flotation processes. Separation Science and Technology, 36 (3), 349-365.

Full Text: S\Sep Sci Tec36, 349.pdf

Abstract: Queous solutions containing heavy metals can be successfully treated by a combination of biosorption and flotation, in order to remove (or recover) the contained metals. Nonliving biomass of yeast Saccharomyces, which is a solid industrial by-product, was found to be a suitable biosorbent of metal ions (zinc, copper, and nickel). It was found also possible to reuse it after the appropriate desorption treatment. Electrokinetic behavior of biomass as well as elution and multiple-cycles operation were investigated. The dispersed-air flotation technique, which was selected for generation of bubbles, was subsequently examined for solid/liquid separation, In order to hart est the metals-loaded biomass downstream. The main parameters affecting the flotation process were studied, Such as the solution pH, the concentration of notation collector (surfactant), the preliminary biomass modification, and the biomass concentration: The biosorptive flotation method was found promising for remediation applications of wastewaters containing toxic metals.

Keywords: Iosorption, Toxic Metals Removal, Flotation, Yeast, Biomass, Dilute Aqueous-Solutions, Cerevisiae, Separation, Cadmium, Adsorption, Recovery, Cations

Bajpai, S.K. (2001), Removal of hexavalent chromium by adsorption onto fireclay and impregnated fireclay. Separation Science and Technology, 36 (3), 399-415.

Full Text: S\Sep Sci Tec36, 399.pdf

Abstract: The removal of hexavalent chromium from its aqueous solutions by adsorption onto fireclay (FC) and impregnated fireclay (IFC) has been studied at 30 degreesC. The adsorption process follows the Langmuir-type adsorption behavior, and the extent of adsorption is more for impregnated fireclay. It is found that electrostatic and H-bonding interactions play a key role in binding the adsorbate molecules to the adsorbent surface. The adsorption process is affected greatly by variation in pH and temperature of the system. Low pH and high temperature favor the adsorption process.

Various kinetic and adsorption parameters such as rate constant for adsorption, intraparticle diffusion rate constant, diffusion coefficient, and adsorption capacity have been evaluated to reflect the experimental findings.

Keywords: Adsorption, Fireclay, Impregnated Fireclay, Hexavalent Chromium, Fly-Ash, Activated Carbon, Aqueous-Solutions, Separation, Effluents

Terzyk, A.P. and Gauden, P.A. (2001), The simple procedure of the calculation of diffusion coefficient for adsorption on spherical and cylindrical adsorbent particles. Separation Science and Technology, 36 (4), 513-525.

Full Text: S\Sep Sci Tec36, 513.pdf

Abstract: The simple method of the calculation of the diffusion coefficient of an adsorbed phase (D_e), based on the analytical solution of Fick’s law of diffusion, for adsorption process is presented. Two shapes of the sorbent granules, i.e., spherical and cylindrical ones, are considered, and the adsorption process is assumed to take place in the Henry’s region of the isotherm. Adopting the method proposed by Korta on the solution of Fick’s law of diffusion, mathematically simple equations are developed to correlate the constant K of the analytical solution: with the value of the relative adsorption as well as with the values of the geometrical parameters of the adsorbent granules. Using these simple equations, one can calculate the values of de and avoid, at the same time, mathematically advanced and time-consuming minimization procedure. Moreover, the procedure is likely to become complicated because of difficult mathematical functions and operations occurring in the equations that describe the, process, for example, Bessel function or the summation from unity to infinity. The presented simplified procedure is adopted for the results of paracetamol adsorption from water solution on two carbons with different shapes of granules, and it is shown that the obtained values of diffusion coefficients are practically the same as those calculated by means of the exact numerical procedure from the analytical solution.

Keywords: Temperature-Dependence, Aqueous-Solutions, Activated Carbon, Neutral pH, Paracetamol

Hasany, S.M., Saeed, M.M. and Ahmed, M. (2001), Sorption of palladium-thiocyanate complexes onto polyurethane foam from aqueous solution using radiotracer technique. Separation Science and Technology, 36 (4), 555-570.

Full Text: S\Sep Sci Tec36, 555.pdf

Abstract: The sorption of palladium-thiocyanate complex onto polyurethane foam (PUF) has been investigated and optimized from aqueous solution of different pHs (1–10) and of acids of varied concentration (0.01–0.5 M). Maximum sorption (~ 99%) of palladium (9.410⁻⁵ M) in the presence of thiocyanate (1.2510⁻² M) ions has been achieved from 0.1 M hydrochloric acid solution within 5 min equilibrating time. The variation of palladium concentration (1.0310⁻⁴ − 1.1610⁻³ M) data were subjected to different sorption isotherms.

The data followed both Freundlich and Dubinin-Radushkevich (D-R) isotherms very well, but Langmuir isotherm is not obeyed at very low concentration. The Freundlich parameters 1/n = 0.54±0.02 and of C_m = 35±7 mmol g⁻¹ have been evaluated, whereas D-R isotherm yields β = -0.003277±0.000193 kJ² mol⁻², X_m = 1.01±0.16 mmol g⁻¹, and of E = 12.3±0.35 kJ mol⁻¹. The Langmuir isotherm gives the value of Q = 0.27±0.08 mmol g⁻¹ and of b = (2.83±0.06)10⁴ L mol⁻¹. The temperature variation (15–55°C) studies have given values of ΔH = -48.9±2.5 kJ mol⁻¹, Δ S = -127.3±8.2 J mol⁻¹ K⁻¹, and of Δ G = -25.2 kJ mol⁻¹ at 298 K. Among the ions tested, thiourea, cyanide, thiosulphate, molybdate, nitrite, and Fe(II) reduce the sorption significantly (31–70%).

Guibal, E., Ruiz, M., Vincent, T., Sastre, A. and Navarro-Mendoza, R. (2001), Platinum and palladium sorption on chitosan derivatives. Separation Science and Technology, 36 (5-6), 1017-1040.

Full Text: S\Sep Sci Tec36, 1017.pdf

Abstract: Chitosan is a unique biopolymer due to its cationic properties in acidic solutions. Protonation of the amino groups induces ion-exchange properties that can be used for anion recovery. As this sorbent is soluble in acidic media, it may be necessary to reinforce its chemical stability using a glutaraldehyde cross- linking treatment. Sorption properties are strongly influenced by the pH of the solution and the presence of competitor anions, especially sulfate anions. This competitor effect may be decreased by the grafting of sulfur derivatives on the chitosan backbone using glutaraldehyde as a linker between the polysaccharide chains and the substituent. Several techniques such as FTIR and SEM-EDAX were used for the chemical characterization of chitosan substitution and for the location of PGM sorption on the sorbent. Sorption isotherms and kinetics were investigated and compared for cross-linked materials and substituted polymers, and special attention was given to the influence of competitor anions. The grafting of sulfur compounds increased sorption capacities and decreased the competition of sulfate and chloride anions. While cross-linked materials sorbed platinum and palladium through anion exchange, the grafting of sulfur moities gave chelating functionalities to the ion-exchange resin.

Keywords: Adsorption, Beads, Chitosan, Chitosan Derivatives, Equilibrium, Ion Sorption, Isotherms, Kinetics, Metal-Ion, N-Carboxymethyl Chitosan, Palladium, Platinum, Removal, Sorption, Sulfur Derivatives

Martellaro, P.J., Moore, G.A., Peterson, E.S., Abbott, E.H. and Gorenbain, A.E. (2001), Environmental application of mineral sulfides for removal of gas-phase Hg(0) and aqueous Hg²⁺. Separation Science and Technology, 36 (5-6), 1183-1196.

Full Text: S\Sep Sci Tec36, 1183.pdf

Abstract: Synthesized and commercially available metal sulfides were evaluated for their ability to adsorb elemental and ionic mercury. The coinage group metal sulfides adsorb elemental Hg(0) vapor stoichiometrically. The mechanism of Hg(0) uptake by the copper and gold sulfides is a redox process resulting in the formation of HgS. The mechanism in the case of Ag₂S involves redox but there is no HgS formation. The relative rates of Hg(0) adsorption increases in the order CuS > Ag₂S > Au₂S > Au₂S₃ corresponding to the metal ion reduction potentials.

The relative rate of Hg(0) adsorption for commercial grade CuS is increased by an activation process which involves making a slurry of the metal sulfide in concentrated oxalic acid followed by drying and then exposure to Hg(0). Relative rates of Hg(0) adsorption were also increased by decreasing the particle size of the metal sulfides. Particle sizes were decreased by synthesis of the metal sulfide in the presence of the particle-size mediating agent CTAB.

The metal sulfides remove ionic mercury from acidic solutions by precipitation with the dissolved sulfide forming HgS. In acidic solution there was no evidence of physical or chemical adsorption between Hg(0) and the metal sulfide. The quantity of ionic Hg²⁺ removal from aqueous solutions is correlated with the solubility of the metal sulfide. Cu₂S was the most soluble metal sulfide tested and thus removed the most ionic mercury from solution by precipitating HgS.

Keywords: Elemental Mercury

Elshani, S., Smart, N.G., Lin, Y.H. and Wai, C.M. (2001), Application of supercritical fluids to the reactive extraction and analysis of toxic heavy metals from environmental matrices-system optimisation. Separation Science and Technology, 36 (5-6), 1197-1210.

Full Text: S\Sep Sci Tec36, 1197.pdf

Abstract: The extraction of Cu²⁺, Pb²⁺, Cd²⁺ and Zn²⁺ utilising supercritical fluid carbon dioxide containing dissolved organophosphorus reagents is shown to be feasible. Using the solubility parameter concept and investigation of a variety of physical parameters favourable extraction conditions of 60°C and 400 atm pressure were determined. Cyanex 302 was found to be the most favourable ligand in terms of stability and ability to complex a range of metal ions. A soil containing substantial amounts of Pb²⁺ and Cd²⁺ was studied using SFE and the technique was found to reduce the levels of leachable metal ions to near US EPA regulatory levels.

Keywords: Carbon-Dioxide, Solvent-Extraction, Organophosphorus Reagents, Tributyl-Phosphate, Light Lanthanides, Chelating-Agents, Cyanex-272, Acid, Cobalt(II), Separation

Yu, Q.M. and Kaewsarn, P. (2001), Desorption of Cu²⁺ from a biosorbent derived from the marine alga Durvillaea potatorum. Separation Science and Technology, 36 (7), 1495-1507.

Full Text: S\Sep Sci Tec36, 1495.pdf

Abstract: The desorption and recovery of Cu²⁺ from a biosorbent material derived from marine alga Durvillaea potatorum were studied. The biosorbent was a pretreated biomass of Durvillaea potatorum with calcium chloride solution and thermal treatment. The Cu²⁺ was adsorbed onto the biosorbent and then desorbed by various elution solutions. Batch desorption tests established a solution of 0.35 M hydrochloric acid as the most appropriate eluting agent. Fixed-bed desorption recovery curves for Cu²⁺ were also obtained. In addition, batch desorption recovery curves for Cu²⁺ were obtained for multiple consecutive adsorption–desorption cycles and the biosorption properties of the biomass for Cu²⁺ were compared after the fifth cycle to evaluate the stability of the biomass. The use of a mixture of 0.35 M hydrochloric acid and 0.5 M calcium chloride as the eluting agent improved the stability of the biosorbent in the multiple adsorption–desorption cycles. The desorption kinetics were similar to those observed in the ad-sorption process. The desorption process was not significantly affected by temperature.

Keywords: Heavy Metal Biosorption, Marine Algae, Durvillaea potatorum, Wastewater Treatment

Kim, J.S., Zhang, L. and Keane, M.A. (2001), Removal of iron from aqueous solutions by ion exchange with Na-Y zeolite. Separation Science and Technology, 36 (7), 1509-1525.

Full Text: S\Sep Sci Tec36, 1509.pdf

Abstract: Iron removal from aqueous solutions by batch ion exchange with a solid Na-Y zeolite has been studied. The pH of the solution was monitored continuously during the ion exchange process and the impact of pH on iron hydroxide precipitation and zeolite structural stability is discussed. In the case of the Fe(II)/Na-Y exchange system, the pH of the iron solutions was low enough to prevent the oxidation of Fe(II) and subsequent hydroxide deposition. The Al and Si contents in the solution were negligible, indicating maintenance of structural integrity, while scanning electron microscopic analysis did not reveal any structural breakdown. The ion exchange equilibrium isotherm, constructed at 291±2 K and a total solution positive charge concentration of 0.1 equiv. Dm^-3, exhibited a sigmoidal shape and a maximum exchange of 74% of the indigenous sodium content: maximum exchange was essentially independent of exchange temperature. An increase in the initial Fe(II) concentration, in the range 0.005-0.05 mol dm^-3, lowered the removal efficiency, but the external Fe(II) was preferred to the indigenous sodium over the entire concentration range. A maximum Fe(II) recovery of 84% from the maximally exchanged zeolite was achieved using 2 mol dm^-3 solutions of NaCl as regenerant while the regenerated Na-Y delivered 68% of the original Fe(II) exchange capacity. The Fe(II) recovery was lower from samples exchanged under reflux conditions, while drying the loaded zeolite at 383 K also suppressed the degree of recovery. The treatment of Fe(III) solutions with Na-Y was not feasible due to the acidity associated with the zeolite/salt slurries, which promotes excessive hydroxide deposition and structural disintegration of the zeolite.

Keywords: Na-Y Zeolite, Ion Exchange, Iron Removal, Water Treatment, Metal Co-Cation, Heavy-Metals, Hydrolysis, Equilibria, Cadmium, Lead

Yalcin, S., Apak, R., Hizal, J. and Afsar, H. (2001), Recovery of copper(II) and chromium(III, VI) from electroplating-industry wastewater by ion exchange. Separation Science and Technology, 36 (10), 2181-2196.

Full Text: S\Sep Sci Tec36, 2181.pdf

Abstract: Two laboratory-scale separation processes have been developed for the recovery of copper(II) from acidic and cyanide-containing alkaline wastewater of electroplating industries. Acidic bath wastes were treated with Dowex 50X8, a strongly acidic cation-exchange resin, and the retained copper was eluted with H₂SO₄. The cyanide-containing alkaline bath waste was first oxidized with excessive hypochlorite, then neutralized, and recovered by the use of Amberlite IRC-718 chelating resin. Copper was eluted with H₂SO₄.

The two different valencies of chromium have been recovered from electroplating-industry wastewater by different separation processes: The predominant valency, Cr(VI), was retained on a strongly basic Dowex 1X8 resin and eluted with a NaCl and NaOH solution. Alternatively, Cr(III), either existing originally in electroplating-industry waste-rinse mixtures or converted from Cr(VI) by reduction with Na₂SO₃, could be recovered by a weakly acidic Amberlite IRC-50 resin and eluted with a solution containing H₂O₂ and NaOH. Where plating industry wastes contain high levels of organic contamination, Cr(VT) would be naturally reduced to Cr(III) upon acidification, and it may be more economical to recover all chromium as Cr(III).

Keywords: Copper(II), Chromium (VI), Chromium(III), Recovery, Removal, Electroplating-Industry Wastewater, Ion Exchange, Wastewater Treatment, Tannery Wastes, Heavy-Metal, Removal, Water, Separation, Resins, Preconcentration, Speciation, Effluents, Cr(III)

Lee, H. and Yi, J.H. (2001), Removal of copper ions using functionalized mesoporous silica in aqueous solution. Separation Science and Technology, 36 (11), 2433-2448.

Full Text: S\Sep Sci Tec36, 2433.pdf

Abstract: Mesoporous silica was synthesized as a support for the removal of copper ions in aqueous solutions. The Sol-gel method in conjunction with neutral surfactants was used. The remaining surfactants were removed by either the Soxhlet or microwave extraction method. Both extractions resulted in the same pore structure of the mesoporous silicas. However, the microwave extraction method reduced the amount of solvents as well as the time required for removing the remaining organic surfactants. 3-(2-aminoethylamino)propyltrimethoxysilane was functionalized onto the mesoporous silica surface. The functional agent removed copper ions and was bonded to the silica surface via covalent bonding. In addition, it was hydrophilic in nature, which reduced external mass-transfer resistance. The removal capacity of mesoporous silica is about 10 times larger than that of a commercial silica, largely because the mesoporous silica has a larger surface area as well as uniform pore structure. The experimental results and model prediction were in good agreement. The results of sensitivity analysis suggested that the mass transfer rate was so fast that little resistance of external mass transfer and diffusion was possible.

Keywords: Molecular-Sieves, Supports, Monolayers, Beads

Ho, Y.S., Chiang, C.C. and Hsu, Y.C. (2001), Sorption kinetics for dye removal from aqueous solution using activated clay. Separation Science and Technology, 36 (11), 2473-2488.

Full Text: S\Sep Sci Tec36, 2473.pdf

Abstract: The kinetics of Basic Red 18 and Acid Blue 9 sorption onto activated clay have been investigated. A batch sorption model, based on the assumption of a pseudo-second order mechanism, has been developed to predict the rate constant of sorption, the equilibrium sorption capacity, and initial sorption rate with the effect of initial dye concentration, activated clay particle size, temperature, and pH value. In addition, an activation energy of sorption has also been determined based on the pseudo-second order rate constants.

Keywords: Activated Clay, Dye, Kinetics, Sorption, Biogas Residual Slurry, Color Removal, Fly-Ash, Waste Slurry, Basic-Dyes, Congo Red, Adsorption, Adsorbent, Water, Equilibrium

Watson, J.H.P., Croudace, I.W., Warwick, P.E., James, P.A.B., Charnock, J.M. and Ellwood, D.C. (2001), Adsorption of radioactive metals by strongly magnetic iron sulfide nanoparticles produced by sulfate-reducing bacteria. Separation Science and Technology, 36 (12), 2571-2607.

Full Text: S\Sep Sci Tec36, 2571.pdf

Abstract: The adsorption of a number of radioactive ions from solution by a strongly magnetic iron sulfide material was studied. The material was produced by sulfate-reducing bacteria in a novel bioreactor. The uptake was rapid and loading on the adsorbent was high due to the high surface area of the adsorbent and because many of the ions were chemisorbed. The structural properties were examined with high-resolution imaging and electron diffraction by transmission electron microscopy. The adsorbent surface area was determined to be 400–500 m²/g by adsorption of heavy metals, the magnetic properties, neutron scattering, and transmission electron microscopy. The adsorption of a number of radionuclides was examined at considerably lower concentration than in previous work with these adsorbent materials. A number of ions studied are of interest to the nuclear industry, particularly the pertechnetate ion (TcO₄⁻). ⁹⁹Tc is a radionuclide thought to determine the long-term environmental impact of the nuclear fuel cycle because of its long half-life and because it occurs normally in the form of the highly soluble pertechnetate ion, which can enter the food chain. This bacteria-generated iron sulfide may provide a suitable matrix for the long-term safe storage of the pertechnetate ion. Also, because of the prevalence of the anaerobic sulfate-reducing bacteria worldwide and, in particular, in sediments, the release of radioactive heavy metals or toxic heavy metals into the environment could be engineered so that they are immobilized by sulfate-reducing bacteria or the adsorbents that they produce and removed from the food chain.

Basu, S. and Malpani, P.R. (2001), Removal of methyl orange and Methylene blue dye from water using colloidal gas aphron: Effect of processes parameters. Separation Science and Technology, 36 (13), 2997-3013.

Full Text: S\Sep Sci Tec36, 2997.pdf

Abstract: Colloidal gas aphron (CGA) was used in a flotation column to remove methyl orange and Methylene blue dye from water. The effect of process parameters, i.e., surfactant type and concentration, CGA flow rate, CGA diameter and gas holdup, pH, residence time, and salt concentration, were studied through measurements of percent dye removal. The overall percent removal of methyl orange and Methylene blue was 95-98% for the range of experimental parameters studied. When the surfactant and dye had a similar charge, 40% removal of dye from the water was achieved. This result was unexpected because dye removal by CGA was thought to be an ion-flotation process. However, the oppositely charged dye and surfactant resulted in 98% removal of dye. Based on these observations, the mechanism for dye removal from water using CGA was elucidated. The removal of methyl orange was higher in alkaline conditions when CGA was generated from the cationic surfactant, hexadecyltrimethyl ammonium bromide. The removal of methyl orange is higher in alkaline condition when generated from the anionic surfactant, sodium dodecylbenzene sulfonate. The percent removal of methyl orange and Methylene blue increased with increased flow rate, decreased CGA diameter, and increased gas holdup. The percent removal of dyes increased with increased residence time of CGA in the flotation column. No effects of surfactant concentration above the cmc or salt concentration on the percent removal of dye were observed within the range of experimental parameters.

Keywords: Coflotation, Colloidal Gas Aphron, Dispersions, Dye Removal From Water, Flotation, Flotation, Methylene Blue, Separation, Soil Matrix, Surfactant Solutions, Surfactants, Suspensions, Waste

Márquez-Montesinos, F., Cordero, T., Rodríguez-Mirasol, J. and Rodríguez, J.J. (2001), Powdered activated carbons from Pinus caribaea sawdust. Separation Science and Technology,