Comparative biosorption of mercuric ions from aquatic systems by immobilized live and heat-inactivated Trametes versicolor and Pleurotus sajur-caju

Abstract

Trametes versicolor and Pleurotus sajur-caju mycelia immobilized in Ca-alginate beads were used for the removal of mercuric ions from aqueous solutions. The sorption of Hg(II) ions by alginate beads and both immobilized live and heat-killed fungal mycelia of T. versicolor and P. sajur-caju was studied in the concentration range of 0.150–3.00 mmol dm −3. The biosorption of Hg(II) increased as the initial concentration of Hg(II) ions increased in the medium. Maximum biosorption capacities for plain alginate beads were 0.144 ± 0.005 mmol Hg(II)/g; for immobilized live and heat-killed fungal mycelia of T. versicolor were 0.171 ± 0.007 mmol Hg(II)/g and 0.383 ± 0.012 mmol Hg(II)/g respectively; whereas for live and heat-killed P. sajur-caju, the values were 0.450 ± 0.014 mmol Hg(II)/g and 0.660 ± 0.019 mmol Hg(II)/g respectively. Biosorption equilibrium was established in about 1 h and the equilibrium adsorption was well described by Langmuir and Freundlich adsorption isotherms. Between 15 and 45 °C the biosorption capacity was not affected and maximum adsorption was observed between pH 4.0 and 6.0. The alginate-fungus beads could be regenerated using 10 mmol dm −3 HCl solution, with up to 97% recovery. The biosorbents were reused in five biosorption–desorption cycles without a significant loss in biosorption capacity. Heat-killed T. versicolor and P. sajur-caju removed 73% and 81% of the Hg(II) ions, respectively, from synthetic wastewater samples.