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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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    Entrapment of Lentinus sajor-caju into Ca-alginate gel beads for removal of Cd(II) ions from aqueous solution: preparation and biosorption kinetics analysis
    (Elsevier Science Bv, 2002) Bayramoğlu, G.; Denizli, A.; Bektaş, S.; Arıca, M.Y.
    A white rot fungus species Lentinus sajor-caju biomass was entrapped into alginate gel via a liquid curing method in the presence of Ca(II) ions. The biosorption of cadmium(II) by the entrapped live and dead fungal biomass has been studied in a batch system. The heat-treatment process enhanced the biosorption capacity of the immobilized fungal biomass. The effect of initial cadmium concentration, pH and temperature on cadmium removal has been investigated. The maximum experimental biosorption capacities for entrapped live and dead fungal mycelia of L. sajur-caju were found to be 104.8 +/- 2.7 mg Cd(II) g(-1) and 123.5 +/- 4.3 mg Cd(II) g(-1), respectively. The kinetics of cadmium biosorption was fast, approximately 85% of biosorption taking place within 30 min. The biosorption equilibrium was well described by Langmuir and Freundlich adsorption isotherms, The change in the biosorption capacity with time is found to fit pseudo-second-order equations. Cadmium binding properties of entrapped fungal preparations have been determined applying the Ruzic equations. Since the biosorption capacities are relatively high for both entrapped live and dead forms, they could be considered as suitable biosorbents for the removal of cadmium in wastewater treatment systems. The biosorbents were reused in three consecutive adsorption/desorption cycles without significant loss in the biosorption capacity. (C) 2002 Elsevier Science B.V. All rights reserved.
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    Selective recovery of mercury by Procion Brown MX 5BR immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes
    (Elsevier Science Bv, 2002) Genç, O.; Arpa, C.; Bayramoğlu, G.; Arıca, M.Y.; Bektaş, S.
    Metal chelating membranes have advantages as adsorbents in comparison to conventional microspheres or beads because they are not compressible and they considerably eliminate internal diffusion limitations. The aim of this communication was to explore in detail the performance of Procion Brown MX 5BR immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes, (also called interpenetrating network, IPN, membranes) for removal of three toxic heavy metal ions, namely, Cd(II), Pb(II) and Hg(II) from aquatic systems. The composite membranes were characterized by elemental analysis, scanning electron microscopy and Fourier Transform Infrared (FTIR) spectroscopy. The incorporated amount of the Procion Brown NIX 5BR was calculated. as 0.036 mumol/cm(2) from the nitrogen and sulphur stoichiometry. The adsorption capacity 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. Adsorption capacity of the membranes increased with time during the first 45 min and then levelled off toward the equilibrium adsorption. The maximum amounts of heavy metal ions adsorbed were found as 18.5, 22.7 and 68.8 mg/g for Cd(H), Pb(H) and Hg(H), respectively. Competitive adsorption of the metal ions was also studied. When the metal ions competed, the adsorbed amounts were found as 1.8 mg Cd(II)/g, 2.2 mg Pb(II)/g and 52.6 mg Hg(II)/g. Under competitive conditions, the system showed a very high selectivity for Hg(H) ions. The membrane can be regenerated by washing with a solution of nitric acid (0.01 M). The desorption ratio achieved was as high as 95%. These membranes are suitable for repeated use for more than five adsorption/desorption cycles without any considerable loss in adsorption capacity. (C) 2002 Elsevier Science B.V. All rights reserved.