Abstract: To develop a new biosorbent for the removal of heavy metals, we studied the adsorption characteristics and mechanism of Pb2+ by Wickerhamomyces anomalus QF-1-1, with high Pb2+ adsorption capacity. The shaking flask method was used to investigate the effects of initial Pb2+ concentration, initial pH value, microbial cell concentration and adsorption time on Pb2+ adsorption by this strain. The adsorption mechanism was studied by group making, chemical treatment and desorption experiments. The results showed that the optimum conditions for obtaining maximum adsorption capacity of 7.29 mg/g and Pb2+ removal rate of 97.89% were found to be pH 5.5, initial Pb2+ concentration 100 mg/L, yeast cell concentration 11 g/L, and absorption time 140 min. After making the –COOH, –NH2 and –PO3 groups on the cell surface, the removal rate of Pb2+ by QF-1-1 decreased from 92.61% to 34.13%、38.69%、77.84%, respectively. Therefore, in terms of decreasing contribution to Pb2+ adsorption, the three groups could be ranked in the following order: –COOH > –NH2 > –PO3. Different chemical treatments had different effects on the Pb2+ adsorption capacity of QF-1-1, which significantly decreased after acid treatment (P < 0.01). The Pb2+ adsorption process was reversible and the adsorbed Pb2+ could be eluted by 0.1 mol/L HCl, 15 mmol/L HNO3, and 1.0 mmol/L ethylenediaminetetraacetic acid (EDTA). The remaining intracellular Pb2+ accounted for less than 4.1% of the total adsorption amount after 4 times elution. Surface adsorption might be the main factor for the removal of Pb2+ by QF-1-1.

Key words: Wickerhamomyces anomalus, biosorption, lead ions