Biosorption of 241Am by immobilized Saccharomyces cerevisiae

Americium-241 is one of the most serious radioactive contaminating nuclides due to its high toxicity and long half-life. The encouraging biosorption of Am-241 from aqueous solutions by free Saccharomyces cerevisiae (S. cerevisiae) has been observed in our previous experiments. In this study, the Am-241 biosorption by immobilized S. cerevisiae and the effect of the various experimental conditions on the adsorption were investigated. The results indicated that the Am-241 biosorption by immobilized S. cerevisiae is still very efficient, and immobilized S. cerevisiae can be used repeatedly or continuously. The biosorption equilibrium was achieved within 2 hours, and more than 92% of Am-241 was removed by immobilized S. cerevisiae in the pH 1-4 range. No significant differences in Am-241 biosorption were observed at 15-45 degreesC. The immobilized S. cerevisiae, even after used repeatedly for 6 times, still could adsorb more than 90% of Am-241 in solutions of 1.08 MBq/l (8.5 mug/l). At this moment, the total adsorption capacity for Am-241 was more than 63.3 KBq/g globe (0.5 mug/g), but has not reached saturation yet. The Am-241 left in solutions with initial concentration of 1.08 MBq/l (8.5 mug/l) was noted as low as similar to10 Bq/l (similar to8.0X10(-5) mug/l) after adsorption by the immobilized S. cerevisiae for 3 times.