Factors affecting silver biosorption by an industrial strain of Saccharomyces cerevisiae

Abstract

Factors affecting silver biosorption by Saccharomyces cerevisiae biomass, obtained as a waste product from industry, were examined. Maximum removal of silver from solution was achieved within 5 min. Increasing the concentration of biomass in experimental flasks from 1 to 8 mg cm -3 decreased both silver accumulation, from 224.7 to 89.5 μmol Ag g -1 dry wt, and associated H + ion release, from 109.4 to 31.7 μmol H + g -1 dry wt. The presence of 1.0 mol dm -3 cadmium or methionine decreased silver biosorption by 40% and 93% respectively. Boiling in 100 mmol dm -3 NaOH or 10 mmol dm -3 sodium dodecyl sulphate decreased silver biosorption by 54% and 25% respectively. A temperature increase from 4°C to 55°C decreased silver biosorption by 9%. The metabolic state of the yeast had no effect on silver biosorption. Decreasing the pH of the silver solution caused a reduction in metal removal by the biomass.