Personal Research Database

Full Text: 1995\Sep Sci Tec30, 2477.pdf

Abstract: A few kinds of complexane types of chemically modified chitosan, i.e., monocarboxymethylated chitosan (MCM-chitosan) and IDA- and DTPA-types of chitosan (IDA- and DTPA-chitosan) were synthesized to examine the adsorption of palladium(II), platinum(IV), and iridium(III) from hydrochloric acid solution as well as the elution of palladium and platinum and compared with those by crosslinked copper(II)-complexed chitosan (crosslinked chitosan). The adsorption of palladium(II) monotonously decreased with increasing hydrochloric acid concentration with all kinds of adsorbents. The adsorption of platinum(IV) also decreased with increasing hydrochloric acid concentration with all kinds of adsorbents except for DTPA-chitosan, with which it decreased in the low concentration region and increased in the high concentration region. The adsorption of iridium(III) also decreased with increasing concentration of hydrochloric acid with all kinds of adsorbents except for IDA-chitosan, but that on DTPA-chitosan was much smaller than other adsorbents. The adsorption on IDA-chitosan increased with increasing hydrochloric acid concentration in its low concentration region, and decreased in the high concentration region, different from other adsorbents. The magnitude of adsorption capacity of each adsorbent for palladium(II) was in the order MCM-chitosan = IDA-chitosan > DTPA-chitosan > crosslinked chitosan, while that for platinum(IV) was in the order, DTPA-chitosan > MCM-chitosan = IDA-chitosan > crosslinked chitosan. The elution of loaded palladium(II)) and platinum(IV)) with hydrochloric acid solution was much improved by chemical modification, especially that of platinum(IV) which was drastically improved by using IDA- and MCM-chitosan.

Keywords: 8-Quinolinol, Adsorbent, Adsorbents, Adsorption, Adsorption Capacity, Capacity, Chemical, Chemical Modification, Chemically Modified Chitosan, Chitosan, Cobalt, Concentration, Hydrochloric Acid, Ions, Modification, Modified, Oxidation, Palladium, Platinum, Solvent-Extraction

? Costa, E.T.H., Winkler-Hechenleitner, A.A. and Gómez-Pineda, E.A. (1995), Removal of cupric ions from aqueous solutions by contact with corncobs. Separation Science and Technology, 30 (12), 2593-2602.

Full Text: 1995\Sep Sci Tec30, 2593.pdf

Abstract: The separation of cupric ions from aqueous solution by adsorption onto modified corncobs (hemicellulose-free) was studied. The adsorption process was found to take similar to 15 minutes to attain equilibrium in experiments with continuous agitation at 35C. The process was found to be pH-dependent, with increasing adsorption as pH increases up to 6.00. There is evidence that the adsorption mechanism is an ion-exchange one involving carboxylate groups, and that two binding sites may be present at the adsorbent. The adsorption was found to fit a Langmuir isotherm, and the parameters n(S) (adsorbent capacity) and b (adsorption intensity) were calculated. The results obtained show that corncobs are an interesting adsorbent because they are available in large quantities at several places in the world at little or no cost, and they retain cupric ions rapidly. The corncobs studied also contain aliphatic and phenolic hydroxyl groups that allow for the incorporation of other functional groups and thus increase the adsorbent capacity.

Keywords: Microcrystalline Cellulose, Adsorption, Sorptions, Lignin, Wood, Skins

? Mandjiny, S., Zouboulis, A.I. and Matis, K.A. (1995), Removal of cadmium from dilute solutions by hydroxyapatite. I. Sorption studies. Separation Science and Technology, 30 (15), 2963-2978.

Full Text: 1995\Sep Sci Tec30, 2963.pdf

Abstract: The removal of toxic metals (such as cadmium) was investigated by using hydroxyapatite, an effective inorganic sorbent, at the ultrafine particle size range. In bench-scale experiments performed batchwise, the influence of the main sorption parameters were examined (i.e., solution pH, sorbent and cadmium concentrations, and temperature) and comparison was attempted between demineralized and tap water. Typical adsorption isotherms of the Langmuir type were calculated; zeta-potential measurements of the hydroxyapatite particles and the release of calcium (during the process) were also examined and related to possible mechanisms occurring during the cadmium removal process.

Keywords: Inorganic Cation-Exchangers, Ions

Saraydin, D., Karadağ, E. and Güven, O. (1995), Adsorptions of some heavy-metal ions in aqueous-solutions by acrylamide maleic-acid hydrogels. Separation Science and Technology, 30 (17), 3287-3298.

Full Text: 1995\Sep Sci Tec30, 3287.pdf

Abstract: In this study, acrylamide-maleic acid (AAm/MA) hydrogels in the form of rod have been prepared by gamma-radiation. They have been used for adsorption of some heavy metal ions such as uranium, iron, and copper. For the hydrogel containing 40 mg of maleic acid and irradiated at 3.73 kGy, maximum and minimum swellings in the aqueous solutions of the heavy metal ions have been observed with water (1480%) and the aqueous solution of iron(III) nitrate (410%), respectively. Diffusions of water and heavy metal ions onto hydrogels have been found to be of the non-Fickian type of diffusion. In experiments of uranyl ions adsorption, Type II adsorption has been found. One gram of AAm/MA hydrogels sorbed 14-86 mg uranyl ions from solutions of uranyl acetate, 14-90 mg uranyl ions from solutions of uranyl nitrate, 16-39 mg iron ions from solutions of iron(IV) nitrate, and 28-81 mg copper ions from solutions of copper acetate, while acrylamide hydrogel did not sorb any heavy metals ions.

Keywords: Hydrogel, Poly(Acrylamide Maleic Acid), Adsorption, Uranyl Ion, Heavy Metal Ions, Amidoxime Groups, Polymer

Carriere, P.P.E., Reed, B.E. and Cline, S.R. (1995), Retention and release of lead by a silty loam and a fine sandy loam. II. Kinetics. Separation Science and Technology, 30 (18), 3471-3487.

Full Text: 1995\Sep Sci Tec30, 3471.pdf

Abstract: The kinetics of lead retention and release by a silty loam and a fine sandy loam was investigated. Batch experiments were conducted to assess the rate and degree of lead retention. The rate of lead sorption onto the soils was determined using lead solution with concentrations of 10, 100 and 1000 mg/L. Kinetics of lead retention was very rapid for both soils. Lead was completely removed from both the 10 and 1.00 mg/L solutions, but partially removed from the 1000 mg/L solutions within the first hour. It was noted, that the rate of lead soption was faster for the 10 and 100 mg/L than the 1000 mg/L solutions. The slower retention kinetics for both soils at the 1000 mg/L lead contamination level can be attributed to surface precipitation effects. Batch extraction experiments were also performed using three different types of washing solutions. Lead release using the CaCl₂ washes was less than the release using EDTA and HCl, but the kinetics of lead release was initially rapid with most of the removal occurring within the first hour for the three washing solutions. It was observed that the lead solution concentration has no effect on lead removAl-During the rapid step for the HCl and EDTA washes, but has some effect for CaCl₂ washes.

Keywords: Heavy-Metals, Adsorption

Saraydin, D., Karadag, E. and Güven, O. (1996), Adsorption of some basic dyes by acrylamide-maleic acid hydrogels. Separation Science and Technology, 31 (3), 423-434.

Full Text: 1996\Sep Sci Tec31, 423.pdf

Abstract: In this study, acrylamide-maleic acid (AAm/MA) hydrogels containing different quantities of maleic acid have been irradiated with gamma-radiation. They have been used in experiments on swelling, diffusion and the adsorption of basic dyes such as Methylene Blue, methyl violet and nile blue. Acrylamide-maleic acid hydrogel containing 40 mgmaleic acid and irradiated at 3.73 kGy has been used for swelling and diffusion studies in water and solutions of basic dyes. For this hydrogel, maximum and minimum swellings have been observed with solutions of nile blue (2000% swelling) and water (1480% swelling). Diffusions of water and dyes within hydrogels have been found to be non-Fickian in character. In experiments on the adsorption of dyes, Type III adsorption has been found. One gram of AAm/MA hydrogel sorbed 0.3-2.2 mg of Methylene Blue, 0.3-3.4 mg of methyl violet and 1.6-3.9 mg of nile blue, while acrylamide hydrogel has not sorbed any basic dye. This result shows that AAm/MA hydrogel can be used as a sorbent for water pollutants such as dyes and immobilization of these organic contaminants in the hydrogels from wastewater can solve one of the most important environmental problems of the textile industry.

Keywords: Hydrogel, Poly(Acrylamide Maleic Acid), Swelling, Adsorption, Basic Dyes, Binding, Blue

Salih, B., Denizli, A. and Piskin, E. (1996), Congo Red-Attached poly (EGDMA-HEMA) microbeads for removal of heavy metal ions. Separation Science and Technology, 31 (5), 715-727.

Full Text: 1996\Sep Sci Tec31, 715.pdf

Abstract: In this study we investigated a new sorbent system, Congo Red-attached poly (EGDMA-HEMA) microbeads, for removal of heavy metal ions from aqueous solutions. Poly (EGDMA-HEMA) microbeads were prepared by suspension copolymerization of ethylene glycol dimethacrylate (EGDMA) and hydroxyethyl methacrylate (HEMA) by using poly (vinyl alcohol), benzoyl peroxide and toluene as the stabilizer, the initiator and the diluent, respectively. Congo Red molecules were then covalently attached to these microbeads. Microbeads (150-200 µm in diameter) with a swelling ratio of 55% and carrying 14.5 µmol Congo Red/g poly mer were used in the adsorption/desorption studies. Adsorption rate and capacity of the microbeads for selected metal ions, i.e., Cd(II), Cu(II), Zn(II) and Pb(II), were investigated in aqueous media containing different amounts of these ions (1-500 ppm) and at different pH values (1.5-7.5). Very high adsorption rates were observed at the beginning and adsorption equilibria were then gradually achieved in about 5-90 minutes. The maximum adsorptions of metal ions onto the Congo Red attached microbeads were 18.3 mg/g for Cd(II), 2.9 mg/g for Cu(II), 53.8 mg/g for Zn(II) and 165 mg/g for Pb(II). However, when the metal ions competed (in the case of adsorption from their mixture), the amounts of adsorption for Cd(II), Zn(II) and Pb(II) were quite close. Desorption of metal ions was studied by using 2 M NaCl (pH 7.0) for Cd(II) ions and 0.1 M HNO₃ (pH 1.0) for Cu(II), Zn(II) and Pb(II) ions. High desorption ratios (more than 85%) were achieved in all cases. Adsorption/desorption cycles showed the feasibility of repeated use of this novel sorbent system.

Keywords: Congo Red, Poly(Egdma-Hema) Microbeads, Heavy Metal Ions, Chelating Polymers, Activated Carbons, Amidoxime Groups, Surface-Acidity, Aluminum-Oxide, Trace-Metals, Sea-Water, Adsorption, Separation, Uranium

Solari, P., Zouboulis, A.I., Matis, K.A. and Stalidis, G.A. (1996), Removal of toxic metals by biosorption onto nonliving sewage sludge. Separation Science and Technology, 31 (8), 1075-1092.

Full Text: 1996\Sep Sci Tec31, 1075.pdf

Abstract: Toxic metals, such as zinc, nickel and cadmium, can be removed from dilute aqueous solutions by sorption onto nonliving sewage sludge applied as finely dispersed biosorbent particles after sterilization and drying. A comparison between the suggested method and precipitation, the most common method used for metals removal, was conducted in parallel. The main parameters examined in single component systems include initial metal concentration, temperature and inhibition of the removal process by the existence of soluble constituents. Adsorption isotherms were employed to describe the metals uptake, the Langmuir types were found to fit the experimental data better than the Freundlich ones. Moreover, the desorption of metals from metal-loaded biomass was investigated. The possible selective separation of metals from binary and ternary mixtures by biosorption, which could lead to the recovery and recycling of the removed metals, was also examined by introducing an illustrative selectivity factor.

Ganguly, S.K. and Goswami, A.N. (1996), Surface diffusion kinetics in the adsorption of acetic acid on activated carbon. Separation Science and Technology, 31 (9), 1267-1278.

Full Text: 1996\Sep Sci Tec31, 1267.pdf

Abstract: The recovery of acetic acid from industrial wastewaters is an important separation problem, and one of the routes suggested for this application is liquid phase adsorption on activated carbon adsorbents. Designing an adsorber for such applications requires knowledge of equilibrium isotherm as well as adsorption rate data. In the present work the kinetics of adsorption of acetic acid on activated carbon has been studied. A three-parameter isotherm model has been used to correlate the equilibrium data, and a combined external film transfer-surface diffusion model has been used to simulate the experimental adsorption rate data. The surface diffusivity values obtained range from 6 to 8.5×10^-7 cm²/s, and the values show a dependence on surface loading. These surface diffusivity values can be used in modeling the column breakthrough behavior for this system.

Keywords: Aqueous-Phase, Model

Balköse, D., Ulutan, S., Özkan, F., Ülkü, S. and Köktürk, U. (1996), Flexible poly(vinyl chloride)-zeolite composites for dye adsorption from aqueous solutions. Separation Science and Technology, 31 (9), 1279-1289.

Full Text: 1996\Sep Sci Tec31, 1279.pdf

Abstract: Flexible poly (vinyl chloride) (PVC) composites having natural zeolite clinoptillolite were prepared by plastisol-plastigel technology. Adsoption of Methylene Blue on each raw material and on composites was studied both from an equilibrium and a rate approach. It was observed that the adsorption capacity of zeolite decreased when it was embedded in composites. The equilibrium uptake of Methylene Blue increased with an increasing zeolite fraction in composites. Methylene blue was adsorbed from a 0.02 g.cm^-3 aqueous solution slowly, but was nearly adsorbed completely with a composite having a 0.3 volume fraction of zeolite. The effective diffusion coefficient of Methylene Blue in composites was of the order of 10^-13 m².s^-1 and decreased with increasing filler fraction.

? Wasay, S.A., Tokunaga, S. and Park, S.W. (1996), Removal of hazardous anions from aqueous solutions by La(III)- and Y(III)-impregnated alumina. Separation Science and Technology, 31 (10), 1501-1514.

Full Text: 1996\Sep Sci Tec31, 1501.pdf

Abstract: New adsorbents, La(III)- and Y(III)-impregnated alumina, were prepared for the removal of hazardous anions from aqueous solutions. A commercially available alumina was impregnated with La(III) or Y(III) ions by the adsorption process. The change in the surface charge due to the impregnation was measured by acid/base titration. The adsorption rate and the capacity of the alumina for La(III) and Y(III) ions were determined. The adsorption characteristics of the La(III)- and Y(III)-impregnated alumina and the original alumina for fluoride, phosphate, arsenate and selenite ions were analyzed under various conditions. The pH effect, dose effect, and kinetics were studied. The removal selectivity by the impregnated alumina was in the order fluoride > phosphate > arsenate > selenite. The impregnated alumina has been successfully applied for the removal of hazardous anions from synthetic and high-tech industrial wastewaters.

Keywords: Selenite Adsorption, Water

? Chang, C.Y., Tsai, W.T. and Lee, H.C. (1996), Desorption kinetics of N, N-dimethylformamide vapor from granular activated carbon and hydrophobic zeolite. Separation Science and Technology, 31 (12), 1675-1686.

Full Text: 1996\Sep Sci Tec31, 1675.pdf

Abstract: Such thermodynamic properties as enthalpy, free energy, and entropy of adsorption have been computed for N, N-dimethylformamide (DMF) vapor on two commercial adsorbents: coconut shell Type PCB of activated carbon and Type DAY of hydrophobic zeolite. The computation is based on the Langmuir adsorption isotherms obtained at 293, 303, and 313 K as reported by Tsai et al. The laden adsorbents were regenerated with hot inert nitrogen gas and studied by thermal gravimetric analysis at three different heating rates. The apparent activation energies (E(des)) Of thermal desorption were determined by using the Friedman method. The zeolite DAY has an adsorption potential higher than that of activated carbon PCB as indicated by the more negative value of the adsorption enthalpy of DMF vapor. The average value of E(des) of zeolite DAY is larger than that of activated carbon PCB.

Keywords: Adsorption

Kondo, K., Sumi, H. and Matsumoto, M. (1996), Adsorption characteristics of metal ions on chitosan chemicallymodified by D-galactose. Separation Science and Technology, 31 (12), 1771-1775.

Full Text: 1996\Sep Sci Tec31, 1771.pdf

Abstract: The adsorption characteristics of metal ions on chitosan chemically modified by D-galactose were examined. The pH dependency on the distribution ratio was found to be affected by the valency of the metal ion, and the apparent adsorption equilibrium constants of the metal ions were determined. The order of adsorption of the metal ions is Ga > In > Nd > Eu for the trivalent metal ions and Cu> Ni > Co for the divalent metal ions. It is believed that amino and hydroxyl groups in the chitosan act as a chelating ligand.

Keywords: Adsorption, Adsorption Equilibrium, Chemically Modified Chitosan, Chitin, Chitosan, Dependency, Derivatives, Distribution, Equilibrium, Galactose, Glutamate Glucan, Hydroxyl, Ion, Metal, Metal Ions, Modified, pH, Sorption, Uranium

Juang, R.S., Tseng, R.L., Wu, F.C. and Lee, S.H. (1996), Liquid-phase adsorption of phenol and its derivatives on activated carbon fibers. Separation Science and Technology, 31 (14), 1915-1931.

Full Text: 1996\Sep Sci Tec31, 1915.pdf

Abstract: The adsorption of three phenolic compounds from aqueous solutions on activated carbon fibers was measured in the 2-5 mol/m³ concentration range at 303 K. High adsorption capacities were obtained for the substituted phenols. Several isotherm equations were tried in order to find an equation which correlates the equilibrium data best. Among the equations tried, the three-parameter equation of Jossens et al. derived thermodynamically and based on a heterogeneous surface adsorption theory was found to be the most satisfactory over the entire range of concentrations. A rate parameter was obtained and used to describe the adsorption process on a quantitative basis. This rate parameter could be successfully correlated against the initial solute concentration.

Keywords: Dilute Aqueous-Solution, Fly-Ash, Removal, Adsorbents, Equilibrium, Sorption, Organics, Silica, Water, Color

? Al Mansi, N.M. (1996), Decolorizing wastewater in a fixed bed using natural adsorbents. Separation Science and Technology, 31 (14), 1989-1995.

Full Text: 1996\Sep Sci Tec31, 1989.pdf

Abstract: The possibility of using sawdust as an adsorbent in a fixed-bed adsorber in decolorizing wastewater as well as batchwise was studied. The Freundlich isotherm was obtained for the adsorption of a basic dyestuff (Maxillon Blue) on wood. The factors studied under isothermal adsorption conditions include feed input velocity, wood particle size, and bed height. The controlling step of adsorption at relatively high velocities is the internal diffusion within the pores rather than the external diffusion. The results showed that the best operating conditions were obtained at an intermediate feed velocity of 0.12 cm/s, a particle diameter of 0.018 cm, and a bed height of 10 cm.

Dasmahapatra, G.P., Pal, T.K., Bhadra, A.K. and Bhattacharya, B. (1996), Studies on separation characteristics of hexavalent chromium from aqueous solution by fly-ash. Separation Science and Technology, 31 (14), 2001-2009.

Full Text: 1996\Sep Sci Tec31, 2001.pdf

Abstract: Hexavalent chromium has been separated from an aqueous solution by fly ash. The particle size distribution and physical properties of fly ash have been illustrated. It is observed that the percent removal of Cr⁶⁺ by fly ash is affected by its concentration in aqueous solution, temperature, particle size and pH. Better separation is obtained at acidic pH and at higher temperature. Particle size has a nonsignificant effect on separation. The reaction kinetics of separation follows first-order kinetics more satisfactorily at higher temperature.

Keywords: Chromium, Fly Ash, Ion Exchange, Separation, Adsorption

Juang, R.S. and Swei, S.L. (1996), Effect of dye nature on its adsorption from aqueous solutions onto activated carbon. Separation Science and Technology, 31 (15), 2143-2158.

Full Text: 1996\Sep Sci Tec31, 2143.pdf

Abstract: Liquid-phase adsorption of two dyes on activated carbon was measured in the 283-323 K temperature range. Higher capacity and faster kinetics of adsorption were obtained for a basic dye than for an acidic dye under comparable conditions, probably due to the different ionic natures of the dyes. The equilibrium data for acidic dye could be well described by the Freundlich equation, but the best-fit model for basic dye changed from the Langmuir to the Freundlich equations when the temperature was raised. In addition, the thermodynamic functions were determined. A plot of the fraction of adsorption against time^1/2 was adopted to describe the adsorption process. It was shown that for an acidic dye the amount of adsorbent used played an important role in the adsorption mechanism.

Keywords: External Mass-Transfer, Color Removal, Fly-Ash, Textile Effluents, Pore Diffusion, Dyestuffs, Equilibrium, Adsorbents, Kinetics, Model

Inoue, K., Hirakawa, H., Ishikawa, Y., Yamaguchi, T., Nagata, J., Ohto, K. and Yoshizuka, K. (1996), Adsorption of metal ions on gallium(III)-templated oxine type of chemically modified chitosan. Separation Science and Technology, 31 (16), 2273-2285.

Full Text: 1996\Sep Sci Tec31, 2273.pdf

Abstract: The oxine type of chemically modified chitosan was prepared by the template crosslinking method employing gallium(III) ion as a template ion. The functional groups of oxine were found to be incorporated into the polymer chain of chitosan at a oxine/glucosamine unit ratio of 1/3. This value agrees with that expected from molecular modeling computation by the molecular mechanics method, Adsorption of molybdenum(VI), vanadium(IV), indium(III), aluminum(III), zinc(II), iron(II), and Cadmium(II) together with gallium(III) on this chemically modified chitosan from dilute sulfuric acid solution was compared with that on the original chitosan. It was found that the pH at which the adsorption of these metals takes place on this chemically modified chitosan shifted to a lower pH than that on the original chitosan. The shift was the greatest for gallium(III) among the metal ions examined, which might be attributable to the template effect of gallium(III) ion. The maximum adsorption capacity of gallium(III) was evaluated as 1.17 mol/kg-dry adsorbent. The selective adsorption of small amounts of gallium(III) and indium(III) from an excess amount of zinc(II) was confirmed from the breakthrough profile of separation using a column packed with this chemically modified chitosan.

Keywords: Adsorbent, Adsorption, Adsorption Capacity, Capacity, Chemically Modified Chitosan, Chitosan, Crosslinking, Functional Groups, Ion, Iron(II), Metal Ions, Metals, Modeling, Modified, Molecular Modeling Computation, pH, Polymer, Profile, Selective, Separation, Sulfuric Acid, Template Crosslinking Method

Saraydin, D., Karadağ, E. and Güven, O. (1996), Behaviors of acrylamide/maleic acid hydrogels in uptake of some cationic dyes from aqueous solutions. Separation Science and Technology,