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    Biosorption of cadmium from aquatic systems by carboxymethyleellulose and immobilized Trametes versicolor
    (Elsevier Science Bv, 2002) Yalcinkaya, Y.; Soysal, L.; Denizli, A.; Arica, M.Y.; Bektas, S.; Genc, O.
    Trametes versicolor basidio spores immobilized onto carboxymethylcellulose were used for the removal of cadmium ions from aqueous solutions. The biosorption of Cd(II) ions on carboxymethylcellulose and both immobilized live and heat-killed fungal mycelia of T. versicolor was studied from aqueous solutions in the concentration range of 30-700 mg/L. The biosorption of Cd(II) ions by the carboxymethylcellulose and both immobilized live and heat-inactivated immobilized preparations increased as the initial concentration of cadmium ions increased in the medium. Maximum biosorption capacity for immobilized live and heat-inactivated fungal mycelia of T. versicolor was found as 124 and 153 mg Cd(II)/g, respectively whereas the amount of Cd(II) ions adsorbed on the plain carboxymethylcellulose beads was 43 mg/g. Biosorption equilibria were established in about I h and the correlation regression coefficients show that the adsorption process can be well defined by Langmuir equation. The temperature change between 15 and 45 degreesC did not affect the biosorption capacity. The effect of pH was also investigated and the maximum adsorption of Cd(II) ions on the carboxymethylcellulose and both live and heat-inactivated immobilized fungal mycelia were observed at pH 6.0. The carboxymethylcellulose-fungus beads could be regenerated using 10 mM HCl, with up to 98% recovery. The biosorbents were used in five biosorption-desorption cycles and no notable loss in the biosorption capacity was observed. 84% and 68% of cadmium ions were removed from synthetic waste water samples for 100 and 200 mg/L initial concentrations, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.
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    Cadmium and mercury uptake by immobilized Pleurotus sapidus
    (Scientific Technical Research Council Turkey, 2002) Yalçınkaya, Y.; Arıca, M.Y.; Soysal, L.; Denizli, A.; Genç, O.; Bektaş, S.
    Pleurotus sapidus basidiospores immobilized onto Ca-alginate beads were used for the removal of cadmium and mercury ions from aqueous solutions. The biosorption of Cd(II) and Hg(II) ions on the alginate beads and both immobilized live and heat inactivated fungal mycelia of Pleurotus sapidus was studied from aqueous solutions in the concentration range of 30-500 mg L-1. The biosorption of Cd(II) and Hg(II) ions by the alginate and both live and heat inactivated immobilized preparations increased as the initial concentration of the ions increased in the medium. Maximum biosorption capacity for immobilized live and heat inactivated fungal mycelia of Pleurotus sapidus was found to be 96.57 mg g(-1) (0.86 mmol g(-1)) and 127.12 mg g(-1) (1.13 mmol g(-1)) for Cd(II) and 207.89 mg g(-1)(1.04 mmol g(-1)) and 287.43 mg g(-1) (1.43 mmol g(-1)) for Hg(II), respectively. The electronegativities and standard electrode potentials of the divalent ions of Group II elements show a definite trend with sorption capacity. Biosorption equilibria were established in about I h and were very well described by Langmuir isotherms. The temperature change between 1.5 and 4.5degreesC did not affect the biosorption capacity. The effect of pH was also investigated and the maximum uptake of metal ions on the alginate and both live and inactivated immobilized fungal mycelia were observed between pH 3.0 and 7.0. The alginate-fun.-us beads were regenerated using 10 mM HCl, with up to 97% recovery, the biosorbents were reused in three biosorption-desorption cycles without any considerable loss in the biosorption capacity.
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    Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes for heavy metal removal
    (Elsevier Science Bv, 2003) Genç, O.; Soysal, L.; Bayramoglu, G.; Arica, M.Y.; Bektas, S.
    The effective removal of toxic heavy metals from environmental samples still remains a major topic of present research. Metal-chelating membranes are very promising materials as adsorbents when compared with conventional beads because they are not compressible, and they eliminate internal diffusion limitations. The purpose of this study was to evaluate the performance of a novel adsorbent, Procion Green H-4G immobilized poly(hydroxyethylmethacrylate (HEMA)/chitosan) composite membranes, for the removal of three toxic heavy metal ions, namely, Cd(II), Pb(II) and Hg(II) from aquatic systems. The Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes were characterized by elemental analysis, scanning electron microscopy and Fourier transform infrared (FTIR) spectroscopy. The immobilized amount of the Procion Green H-4G was calculated as 0.018 +/- 0.003 mumol/cm(2) from the nitrogen and sulphur stoichiometry. The adsorption capacity of Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes for selected heavy metal ions from aqueous media containing different amounts of these ions (30-400 mg/l) and at different pH values (2.0-6.0) was investigated. The amount of Cd(II), Pb(II) and Hg(II) adsorbed onto the membranes measured at equilibrium, increased with time during the first 45 min and then remained unchanged toward the equilibrium adsorption. The maximum amounts of heavy metal ions adsorbed were 43.60 +/- 1.74, 68.81 +/- 2.75 and 48.22 +/- 1.92 mg/g for Cd(II), Pb(II) and Hg(II), respectively. The heavy metal ion adsorption on the pHEMA/chitosan membranes (carrying no dye) were relatively low, 6.31 +/- 0.13 mg/g for Cd(II), 18.73 +/- 0.37 mg/g for Pb(II) and 18.82 +/- 0.38 mg/g for Hg(II). Competitive adsorption of the metal ions was also studied. When the metal ions competed with each other, the adsorbed amounts were 12.74 +/- 0.38 mg Cd(II)/g, 28.80 +/- 0.86 mg Pb(II)/g and 18.41 +/- 0.54 mg Hg(II)/g. Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) membranes can be regenerated by washing with a solution of nitric acid (0.01 M). The percent desorption achieved was as high as 95%. These novel membranes are suitable for repeated use for more than five adsorption/desorption cycles without any considerable loss in adsorption capacity. Adsorption equilibria were well described by Langmuir equation. It can be concluded that Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) membranes may effectively be used for the removal of Cd(II), Pb(II) and Hg(II) ions from aqueous solutions. (C) 2002 Elsevier Science B.V. All rights reserved.