Biosorption of heavy metal ions on immobilized white-rot fungus Trametes versicolor

Abstract

Trametes versicolor mycelia were immobilized in carboxymethylcellulose, CMC, beads via entrapment, and the bead containing immobilized fungus spores were incubated at 30 degreesC for 3 days to attain uniform growth on the bead surface. After incubation, the live and heat inactivated immobilized fungus on the CMC beads were used for the biosorption of Cu2+, Pb2+ and Zn2+ ions. Plain CMC beads were used as a control system. The biosorption of Cu2+, Pb2+ and Zn2+ ions by the CMC and both live and inactivated immobilized preparations increased as the initial concentration of Cu2+, Pb2+ and Zn2+ ions in the medium increased. The maximum biosorption capacities for both immobilized live and heat inactivated Trametes versicolor were 1.51 and 1.84 mmol Cu2+, 0.85 and 1.11 mmol Pb2+ and 1.33 and 1.67 mmol Zn2+ per g of dry biosorbents, respectively. Biosorption equilibrium was established in about 1.0h and the equilibrium was well described by Langmuir and Freundlich isotherms. A temperature change in the range of 15-45 degreesC did not affect the biosorption capacity. The affect of pH was also investigated and the maximum adsorption of Cu2+, Pb2+ and Zn2+ ions on the CMC and both live and inactivated immobilized fungal biomass was observed between pH 4.0 and 6.0. The CMC beads with the immobilized fungus can be regenerated using 10 mM HCl, with up to 97% recovery of the metal ions; the biosorbents reused up to five biosorption-desorption cycles without any major loss in the biosorption capacity. (C) 2003 Elsevier B.V. All rights reserved.