[Studies on biosorption of Pd2+ by bacteria]

The strain R08, showed relatively strong ability of adsorbing Pd2+, was screened from different source of bacterial strains. The strain R08 was identified as Bacillus licheniformis. The optimum pH value of Pd2+ biosorption by R08 dead biomass is 3.5. The biosorption is a rapid and non-temperature dependent process. The biomass and Pd2+ initial concentration in solution affected the biosorption process. The bosorptive capacity could reach 224.8 mg/g under the conditions of Pd2+ 200 mg/L, 0.4 g biomass/L, pH3.5 and 30 degrees C for 45 min. TEM observation showed that R08 biomass is able to adsorb and reduce Pd2+ ions to Pd0 particles. IR spectrum analysis indicated that -COO- and HPO(4)2- groups on the cell walls may involve in process of adsorbing Pd2+.