Personal Research Database

Full Text: S\Sep Sci Tec37, 431.pdf

Abstract: The kinetics of particle deposition onto the surface of spherical collector particles suspended in a stirred batch vessel was investigated. The study considered monodisperse particle and monodisperse spherical collector particles, The Langmuir model for the deposition process was presented with model parametric study as well as model limiting, cases of Smoluchowski analysis and equilibrium state. A method for obtaining the model parameters from model limiting cases was demonstrated. The model was experimentally tested by studying the deposition of small carbon particles onto plastic spheres. This is useful in the de-inking process of waste paper using plastic spheres. The obtained deposition curves are fitted to the model. The estimated parameters from model limiting cases are in agreement with those, obtained from the full deposition curves fitted to Langmuir kinetics. The maximum number of carbon particles that can deposit oil plastic particles is estimated theoretically from geometrical analysis. The estimated value is very close to that determined from the model.

Keywords: Orthokinetic Coalescence Efficiency, Simple Shear-Flow, In-Oil Emulsions, Stability

Serrano, J., Granados, F., Bertin, V. and Bulbulian, S. (2002), Speciation of some ²³⁵U fission products in nitrate solution and their sorption behavior on thermally treated hydrotalcites. Separation Science and Technology, 37 (2), 329-341.

Full Text: S\Sep Sci Tec37, 329.pdf

Abstract: ²³⁵U fission products and their daughter radioisotopes sorption behavior on calcined hydrotalcite were studied through batch and dynamic experiments. Electrophoresis showed that ⁹⁹Mo and ^99mTc (the decay product of ⁹⁹Mo) were present in the solution mainly as anions. ¹⁰³Ru was found as neutral and anionic species and ¹³¹I formed an insoluble compound. ¹³²Te was present only as a neutral species. It was found that under the utilized experimental conditions, ⁹⁹Mo presented the highest sorption value on calcined hydrotalcite, followed by ^99mTc, ¹³¹I, ¹⁰³Ru, and ¹³²Te. Cations such as ¹⁴⁰Ba²⁺ and ¹⁴⁰La³⁺ were also retained by calcined hydrotalcite although in smaller proportions. It was also found that a very high concentration of NO₃^-, anions in the solution decreased the sorption of the radioactive anions on calcined hydrotalcite.

Keywords: Anion-Exchange, Removal

San Miguel, G., Fowler, G.D. and Sollars, C.J. (2002), Adsorption of organic compounds from solution by activated carbons produced from waste tyre rubber. Separation Science and Technology, 37 (3), 663-676.

Full Text: S\Sep Sci Tec37, 663.pdf

Abstract: Activated carbons produced from waste tyre rubber have shown exceptional characteristics for the adsorption of organic species from solution. Adsorption capacities were found to be dependent primarily on the degree of activation and the molecular size of the adsorbate compound. For the purpose of this work, a series of activated carbons were produced by steam activation of waste tyre rubber at 925degreesC over a period of 80-640 min. The resulting carbons were investigated for their porosity, using nitrogen gas adsorption, and for their aqueous adsorption characteristics, using phenol, Methylene blue, and textile dyes Turquoise H-A and Red H-E2B. Two widely used commercial adsorbents were also tested for comparative purposes. Aqueous adsorption data were modeled to the Langmuir equation in order to determine the adsorption capacities (X-m) and affinity parameters (b) associated with each sample. Rubber-derived carbons proved superior to the commercial adsorbents for the removal of medium and large molecular weight compounds from solution, which was attributed to their extensive total micropore volume and external surface area.

Keywords: Activated Carbon, Adsorption, Dyes, Pyrolysis, Tyres, Vacuum Pyrolysis, Scrap Tires, Chars, Oils, Air

Pagnanelli, F., Esposito, A., Toro, L. and Vegliò, F. (2002), Copper and cadmium biosorption onto Sphaerotilus natans: Application and discrimination of commonly used adsorption models. Separation Science and Technology, 37 (3), 677-699.

Full Text: S\Sep Sci Tec37, 677.pdf

Abstract: In this paper, the experimental data of copper and cadmium biosorption onto Sphaerotilus natans obtained under different operating conditions of pH (3 divided by 6 units) and biomass concentration (0.5 divided by 2 g/L) were reported. These experimental data, showing the good separative performances of S. natans and the strong effect of the selected operative factors, were represented by three different empirical models: Langmuir. Freundlich, and Redlich-Peterson isotherms. A statistical representation of the characteristic model parameters (parameter standard deviation and regression coefficient) along with a model discrimination analysis (model residual variance, F-test and residual analysis) were proposed in order to suggest a standardized procedure for treating the biosorption data.

Keywords: Heavy Metal Biosorption, Langmuir and Freundlich Isotherms, Model Discrimination, Iron(III)-Cyanide Complex Anions, Rhizopus-arrhizus, Aqueous-Solutions, Arthrobacter sp, Ion-Exchange, Metal-Ions, Equilibrium, Surfaces, Biomass, Isotherms

Chah, S., Kim, J.S. and Yi, J.H. (2002), Separation of zinc ions from aqueous solutions using modified silica impregnated with CYANEX 272. Separation Science and Technology, 37 (3), 701-716.

Full Text: S\Sep Sci Tec37, 701.pdf

Abstract: Di-2, 4, 4-trimethylpentyl phosphinic acid (CYANEX 272) was immobilized on a silica surface after it was treated with dichlorodimethylsilane and chlorotripropylsilane. The resulting adsorbent prepared showed an excellent selectivity for zinc ion in aqueous solutions and was stable under acidic conditions. Change in surface and pore structure were investigated by means of FT-IR and BET. respectively. The metal ion adsorption capacity order of the resulting adsorbent (silica powder impregnated with CYANEX 272 after silanization of dichlorodimethylsilane, SPDC) was Zn²⁺ > Co²⁺ > Cu²⁺ > Cd²⁺ > Ni²⁺ in the pH range of 2-5. Fixed bed tests were conducted in order to evaluate the efficiency of removal of metal ions using the SPDC, and a breakthrough curve was obtained for the zinc solution. The adsorbed zinc ions could be recovered by treatment with 0.1 M HCl, which permits cyclic use after regeneration.

Keywords: CYANEX 272, Cyclic Use, Selectivity, Sulfate-Solutions, Copper Ions, Extraction, Adsorption, Adsorbents, Recovery, Cadmium, Removal, Zn(II), Resins

Ozkara, S., Yavuz, H., Patir, S., Arıca, M.Y. and Denizli, A. (2002), Separation of human-immunoglobulin-G from human plasma with L-histidine immobilized pseudo-specific bioaffinity adsorbents. Separation Science and Technology, 37 (3), 717-731.

Full Text: S\Sep Sci Tec37, 717.pdf

Abstract: The pseudo-biospecific affinity ligand L-histidine immobilized poly(2-hydroxyethylmethacrylate) (PHEMA) in spherical form (100-150 mum in diameter) was used for the affinity chromatographic separation of human-immunoglobulin-G (HIgG) from aqueous solutions and human plasma. The PHEMA adsorbents were prepared by a radical suspension polymerization technique. Reactive aminoacid-ligand L-histidine was then immobilized by covalent binding onto these adsorbents. Elemental analysis of immobilized L-histidine for nitrogen was estimated as 62.3 mg L-histidine/g of PHEMA. The maximum HIgG adsorption on the L-histidine immobilized PHEMA adsorbents was observed at pH 7.4. The non-specific HIaG adsorption onto the plain PHEMA adsorbents was very low- (about 0.167 mg/g). Higher adsorption values (up to 3.5 mg/g) were obtained when the L-histidine immobilized PHEMA adsorbents were used from aqueous solutions. Much higher amounts of HIgG were adsorbed from human plasma (up to 44.8 mg/g). Adsorption capacities of other blood proteins were obtained as 2.2 mg/g for fibrinogen and 2.8 mg/g for albumin. The total protein adsorption was determined as 52.1 mg/g. The affinity microbeads allowed the one-step separation of HIgG from human plasma. The HIgG molecules could be repeatedly adsorbed and desorbed with these L-histidine-immobilized PHEMA adsorbents without noticeable loss in their HIgG adsorption capacity.

Keywords: Hollow-Fiber Membranes, Protein-A, Peptide Libraries, Polyhydroxyethylmethacrylate Microbeads, Affinity-Chromatography, Kinetic Aspects, Purification, Adsorption, Removal, Ligands

Snukiškis, J. and Kaušpediene, D. (2002), Combined sorption of cobalt(II) and nonionic surfactant by polyacrylic acid-functionalized cation exchanger. Separation Science and Technology, 37 (4), 921-936.

Full Text: S\Sep Sci Tec37, 921.pdf

Abstract: The kinetics of combined sorption of cobalt(II) and nonionic surfactant ALM-10 by hydrogen form of Purolite C 106 polyacrylic acid-functionalized cation exchanger were investigated: kinetic curves were obtained determining the concentration of nonionic surfactant spectrophotometrically, and that of cobalt(II) complexometrically. Reducing the initial solution acidity from pH 5 to 8, the coefficients of intraparticle diffusion (D) for cobalt(II) increase, although they decrease as the cation exchanger saturation increases. The sorption of the surfactant proceeds slower than that of cobalt(II).

Regeneration of the cation exchanger was performed using 0.7 M HCl for the removal of cobalt(II), 0.5 M NaOH for the removal of the surfactant, and 0.7 M HCl for the conversion to hydrogen form. Hydrogen form of Purolite C 106 can be applicable for the simultaneous removal of nonionic surfactant and cobalt(II) from plating rinse sewage to recover water for recycling.

Keywords: Heavy Metal, Nonionic Surfactant, Sorption, Cation Exchanger, Ion-Exchange, Metal-Ions, Equilibrium, Adsorption, Nickel, Resins

Park, S.W., Kim, S.S. and Sohn, I.J. (2002), Chemical equilibrium of trioctylmethylammonium chloride with aqueous solution of Cr(VI). Separation Science and Technology, 37 (4), 957-971.

Full Text: S\Sep Sci Tec37, 957.pdf

Abstract: The distribution and dissociation equilibria of phase-transfer catalyst, trioctylmethyl-ammonium chloride (Q(+)Cl(-)), for the system of QCI-toluene-aqueous HCrO₄^- solutions were measured at 298K for the systems of toluene-water or -aqueous electrolyte solutions.

The evaluated distribution coefficients of trioctylmethylammonium chloride and the complex formed between trioctylmethylammonium cation and HCrO₄^- were correlated as a function of the ionic strength in the aqueous solutions. The dissociation constants, K₁ and K₂, were independent of ionic strength.

Keywords: Distribution Coefficient, Dissociation Constant, Trioctylmethylammonium Chloride, Ionic Strength, Salting-Out Parameter, Emulsion Liquid Membranes, Chromium(VI), Aliquat-336, Separation, Extraction, Recovery, Kinetics

? Pickett, J.L., Naderi, M., Chinn, M.J. and Brown, D.R. (2002), The adsorption and decomposition of cyanogen chloride by modified inorganic molecular sieves. Separation Science and Technology, 37 (5), 1079-1093.

Full Text: 2002\Sep Sci Tec37, 1079.pdf

Abstract: Aluminosilicate and silicate porous solids have been evaluated as supports for triethylenediamine (TEDA) for the adsorption and decomposition of cyanogen chloride. A series of silica-gel supports has been used to study the effect of varying pore size. A series of faujasitic zeolites has been used to examine the effect of the cation exchange capacity of the support and the type of exchangeable cation. Results show that the activity of adsorbed TEDA towards cyanogen chloride appears to increase with increasing support pore diameter, and TEDA seems to be activated by basic adsorption sites on the support. Cesium-exchanged zeolite supports are particularly active. In general, zeolite supports appear to confer significantly higher activity to TEDA than traditional activated carbon supports. A series of mesoporous MCM-41 and AlMCM-41 supports has also been studied, but the activities of adsorbed TEDA are lower than expected. Significantly, the specific surface area of the inorganic supports does not seem to be a primary factor in controlling adsorbed TEDA activity.

Keywords: Acid Sites, Activated Carbon, Activity, Adsorbents, Adsorption, Capacity, Carbon, Catalysis, Cation Exchange Capacity, Chloride, Cyanogen Chloride, Decomposition, Ethanol, Exchangeable Cation, Inorganic, Ion, MCM-41, Modified, Pore Size, Porous, Separation, Silica, Silica Gel, Silicate, Sites, Specific Surface Area, Supports, Surface, Surface Area, Triethylenediamine, Zeolite, Zeolite-Y

Raichur, A.M. and Panvekar, V. (2002), Removal of As(V) by adsorption onto mixed rare earth oxides. Separation Science and Technology, 37 (5), 1095-1108.

Full Text: S\Sep Sci Tec37, 1095.pdf

Abstract: Arsenic pollution of water is a major problem faced worldwide. Arsenic is a suspected carcinogen in human beings and is harmful to other living beings. In the present study, a novel adsorbent was used to remove arsenate [As(V)] from synthetic solutions. The adsorbent, which is a mixture of rare earth oxides, was found to adsorb As(V) rapidly and effectively. The effect of various parameters such as contact time, initial concentration, pH, and adsorbent dose on adsorption efficiency was investigated. More than 90% of the adsorption occurred within the first 10 min and the kinetic rate constant was found to be about 3.5 mg min⁻¹. Adsorption efficiency was found to be dependent on the initial As(V) concentration, and the adsorption behavior followed the Langmuir adsorption model. The optimum pH was found to be 6.5. The presence of other ions such as nitrate, phosphate, sulphate, and silicate decreased the adsorption of As(V) by about 20–30%. The adsorbed As(V) could be desorbed easily by washing the adsorbent with pH 12 solution. This study demonstrates the applicability of naturally occurring rare earth oxides as selective adsorbents for As(V) from solutions.

Keywords: Arsenic, Adsorption, Rare Earth Oxide, Anion, Desorption

Ramesh, A., Mohan, K.R., Seshaiah, K. and Choudary, N.V. (2002), Removal of beryllium from aqueous solutions by zeolite 4A and bentonite. Separation Science and Technology, 37 (5), 1123-1134.

Full Text: S\Sep Sci Tec37, 1123.pdf

Abstract: The adsorption and desorption of beryllium on zeolite 4A and bentonite has been studied using batch sorption studies. Parameters such as time of equilibrium, effect of pH, and effect of adsorbent dose on adsorption were studied. The adsorbents exhibited good sorption potentials for beryllium with a peak value at pH 5.0. The adsorption followed the Freundlich and Langmuir adsorption models. About 75% and more removal occurred within 20 min, and an equilibrium was attained at around 90 min for both adsorbents. Beryllium adsorption by zeolite 4A is higher than zeolite 13X and bentonite. The desorption studies were carried out using sodium chloride solution, and the effect of NaCl concentration on desorption was studied. Maximum desorption of 87% occurred with 10% NaCl.

Keywords: Beryllium, Zeolite 4A, Zeolite 13X, Bentonite, Removal, Aqueous Solutions

Venkatesan, K.A., Srinivasan, T.G. and Rao, P.R.V. (2002), Removal of complexed mercury from aqueous solutions using dithiocarbamate grafted on silica gel. Separation Science and Technology, 37 (6), 1417-1429.

Full Text: S\Sep Sci Tec37, 1417.pdf

Abstract: Sorption of mercury from aqueous solution by dithiocarbamate grafted on silica gel was investigated. The influence of pH, Hg²⁺ concentration, time, temperature, and presence of various anions and complexing agents on the sorption of mercury was studied. The sorption data obtained as a function of mercury concentration was fitted into a Langmuir adsorption model, which showed a sorption capacity of similar to 61 mg/g. Kinetic data indicated a very rapid sorption in the early stages of equilibration. The endothermic enthalpy change accompanied by the sorption of mercury from 0.1 M HCl media was found to decrease from 44.7 to 24.4 kJ/mol when the initial concentration of mercury was increased from 7.5×10^-4 to 1.5×10^-3 M.

Keywords: Separation, Monolayers, Surface

Milich, P., Möller, F., Píriz, J., Vivó, G. and Tancredi, N. (2002), The influence of preparation methods and surface properties of activated carbons on Cr(III) adsorption from aqueous solutions. Separation Science and Technology, 37 (6), 1453-1467.

Full Text: S\Sep Sci Tec37, 1453.pdf

Abstract: Activated carbons were prepared from eucalyptus wood, by using three different ‘physical’ activating methods: air and CO₂ partial, gasification of wood char (2 hr, 400degreesC and 800degreesC, respectively), and direct CO₂ partial gasification of wood sawdust. The three activated carbons were then oxidized with HNO₃ for increasing the surface concentration of oxygenated functions, and Cr(III) aqueous solution adsorption isotherms were determined for each oxidized carbon. Characterization of the carbons were done through elemental analysis, N₂ adsorption, and Fourier transform infrared spectroscopy spectra. Results show that oxidized activated carbons prepared from air gasification have the higher Cr(III) adsorption capacity. Conclusions about chemical functions formed onto the carbon surface and the relationship with Cr(III) adsorption are exposed

Keywords: Acid, Activated Carbon, Activated Carbons, Adsorption, Adsorption Isotherms, Chromium, Chromium(III), Eucalyptus Wood, Isotherms, Liquid Phase Adsorption, Nitric Acid Oxidation, Porous Structure, Preparation, Sawdust, Temperature, Wood

Lenz, K., Beste, Y.A. and Arlt, W. (2002), Comparison of static and dynamic measurements of adsorption isotherms. Separation Science and Technology, 37 (7), 1611-1629.

Full Text: S\Sep Sci Tec37, 1611.pdf

Abstract: Adsorption isotherms can be determined experimentally by using either static or dynamic measuring methods. The adsorption behavior of the system dichloromethane-n-hexane on two normal-phase silica-gels was measured both statically by using the circulation method and dynamically by using the frontal analysis and the perturbation method. As a matter of conformity, adsorption excess isotherms, which are the results of static methods, should have to be converted into loading isotherms.

Analytical and different numerical conversion methods using different assumptions are presented and compared to each other. A conformity between the results of the analytical conversion method and the dynamically measured adsorption isotherms can be established if the decrease of the porosity with increasing loading is also taken into consideration.

Keywords: Liquid

Ohto, K., Inoue, S., Eguichi, N., Shinohara, T. and Inoue, K. (2002), Adsorption behavior of lead ion on calix[4]arene tetracarboxylic acid impregnated resin. Separation Science and Technology, 37 (8), 1943-1958.

Full Text: S\Sep Sci Tec37, 1943.pdf

Abstract: The resins impregnating calix[4]arene tetracarboxylic acid into XAD-7 has been prepared to investigate adsorption behavior of lead ion. The leakage of the impregnated reagent to an aqueous solution is found to be negligible. The sequence in the adsorptive selectivity series for divalent metal ions on the present resin is as follows: Pb much greater than Cu > Zn > Ni approximate to Co. This sequence is also the same with that of the extractive selectivity series of p-t-octylcalix[4]arene as an extractant. The other adsorption properties of the resin for metal ions are similar to the extractive properties of the corresponding calix[4]arene tetracarboxylic acid. Maximum adsorption capacity of lead ion on the resin is found to be 0.33 mol kg^-1. For endurance test, even in eight times repetitive experiment of adsorption followed by elution of lead, the resin is devitalized and available for repeatability. Column chromatographic separation of lead and zinc ions as an industrial application is also carried out. Selective adsorption of trace amounts of lead ion over excess amount of zinc ion is achieved.

Keywords: Calix[4]Arene Carboxylic Acid, Impregnated Resin, Adsorptive Separation, Lead Ion, Column Chromatography, Repetition Test, Calixarene Carboxylate Derivatives, Solid-Phase Extraction, Metal-Ions, Solvent-Extraction, Separation, Silver(I), Binding

Senel, S., Denizli, F., Yavuz, H. and Denizli, A. (2002), Bilirubin removal from human plasma by dye affinity microporous hollow fibers. Separation Science and Technology, 37 (8), 1989-2006.

Full Text: S\Sep Sci Tec37, 1989.pdf

Abstract: Bioaffinity adsorption has a unique and powerful role as a support tool in the removal of toxic substances from human plasma. Synthetic hollow-fiber membranes have advantages as support matrices in comparison to conventional hemoperfusion columns because they are not compressible and they eliminate internal diffusion limitations. In this study, Cibacron Blue F3GA was covalently attached onto commercially available microporous polyamide hollow-fiber membranes for bilirubin removal from hyperbilirubinemic human plasma. Different amounts of Cibacron Blue F3GA were attached on the polyamide hollow-fibers by changing the dye-attachment conditions, i.e., initial dye concentration, addition of sodium carbonate, and sodium chloride. The maximum amount of Cibacron Blue F3GA attachment was obtained at 42.5 mumol g^-1 when the hollow fibers were treated with 3 M HCl for 30 min before performing the dye attachment. The nonspecific bilirubin adsorption on the unmodified polyamide hollow-fiber membranes was 0.65 mg g^-1 from human plasma. Higher bilirubin adsorption capacities, of up to 39.7 mg g^-1, were obtained with the Cibacron Blue F3GA-attached polyamide hollow-fiber membranes. Further increase in bilirubin adsorption was obtained as 48.9 mg g^-1. Bilirubin molecules interacted with these adsorbents directly. Contribution of albumin adsorption on the bilirubin adsorption was much pronounced. Bilirubin adsorption increased with increasing temperature and maximum adsorption was observed at 37degreesC.

Keywords: Hyperbilirubinemia, Bilirubin Removal, Cibacron Blue F3GA-Attached Polyamide Hollow Fibers, Packed-Bed Column, Albumin Adsorption, Poly(Egdma-Hema) Microbeads, Polymer Resins, Amino-Acid, Chromatography, Membranes, Pendants, Sorption, Beads

Ruiz, M., Sastre, A. and Guibal, E. (2002), Pd and Pt recovery using chitosan gel beads. I. Influence of the drying process on diffusion properties. Separation Science and Technology, 37 (9), 2143-2166.

Full Text: S\Sep Sci Tec37, 2143.pdf

Abstract: Chitosan is very efficient at removing metal ions, especially precious metals. Sorption kinetics can be improved by the preparation of chitosan gel beads, using a coagulation procedure. However, this process leads to the formation of beads containing very high water yields, which prevent chitosan from being an economically competitive sorbent for large-scale industrial applications, for reasons linked to transport costs and handling. The air-drying of chitosan gel beads resulted in a decrease in the sorption rate, while the sorption performance at equilibrium was not influenced by the drying step. The influence of re-hydration was examined. The drying of beads saturated with saccharose was considered a simple alternative treatment, to prevent the restriction of the polymer network and improve sorption rate. The influence of these different treatments on both sorption kinetics and sorption isotherms was studied for the recovery of platinum and palladium from dilute solutions.

Keywords: Platinum, Palladium, Chitosan, Glutaraldehyde Cross-Linking, Sorption Isotherms, Sorption Kinetics, Drying Process

Bohrer, D., do Nascimento, P.C., Seibert, E. and de Carvalho, L.M. (2002), Polyethylene powder as an adsorbent for complexing dyes: Influence of dye structure, solvent, pH, and ionic strength. Separation Science and Technology,