BIOSORPTION OF AMERICIUM-241 BY SACCHAROMYCES CEREVISAE:PRELIMINARY EVALUATION AND MECHANISM

摘要

As an important radioisotope in nuclearindustry and other fields, americium-241 isone of the most serious contaminationconcerns duo to its high radiation toxicity andlong half-life. In this experiment, thebiosorption of 241Am from solution by afungus, Saccharomyces cerevisiae (S.Cerevisiae), and the effects of variousexperimental conditions on the biosorptionand the mechanism were explored.The preliminary results showed that S.Cerevisiae is a very efficient biosorbent. Anaverage of more than 99% of the total 241Amcould be removed by S. cerevisiae of 2.1g/L(dry weight) from 241Am solutions of2.22MBq/L -555 MBq/L (Co). The adsorptionequilibrium was achieved within 1 hour andthe optimum pH ranged 1-3.The culture times of more than 16 hourswere suitable and the efficient adsorption of241Am by the S. cerevisiae could be noted. Thebiosorption of 241Am by the decomposed cellwall, protoplasm or cell membrane of S.cerevisiae was same efficient as by the intactfungus, but the some components of S.Cerevisiae, such as protein and acylationgroup had obvious effect on adsorption.When the concentrations of coexistent Eu3+,Nd3+ were 100 times more than that of 241Am,the adsorption rates would drop to 65%.However, most of the investigated acidic ionshave no significant influence on the 241Amadsorption but minute change of pH value,while the saturated EDTA can strong inhibitthe biosorption of 241Am.