Factors affecting silver biosorption by an industrial strain of Saccharomyces cerevisiae

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.