In order to investigate the immobilization ways of U(VI) on Gram-positive bacteria Kocuria sp. and Gram-negative bacteria Shewanella putrefaciens, we investigated the interaction behavior under different conditions by batch experiment. U(VI) products on Kocuria sp and Shewanella putrefaciens were characterized by SEM, XRD, FTIR, and XPS techniques. SEM-EDS results presented U(VI) mineral-like precipitation formed on the cell surface which contained high percentage of P and U elements. XPS results also confirmed the appearance of bond P-O-U. XRD results showed uranium phosphate biomineral existed as chernikovite on the cell surface of S. putrefaciens. and Kocuria sp. at slightly acid pH, but not at pH &gt; 7.0. According to FTIR analysis, in addition to PO43- groups, C=O, -OH, -COOH groups might play important roles in complexation with U(VI). The bioprecipitation process of U(VI) on S. putrefaciens. and Kocuria sp. required longer time than sorption process, indicating that bioprecipitation was induced by the biosorption process. Concentrated U(VI) on the cell surface via fast biosorption might provide nucleation sites for the precipitation to insoluble minerals, while the formation of U(VI) biomineral led to the relatively permanent immobilization of U(VI). Meanwhile we found that S. putrefaciens. cell come together before biomineralization. Our findings highlight the synergistic biosorption and bioprecipitation process of S. putrefaciens. and Kocuria sp. for U(VI) immobilization, which are of significance in predicting the U(VI) immobilization properties and preventing the migration of U in aqueous. The bacterially mediated U(VI) biomineralization, more stable to oxygen over a wide pH range, will be a complementary approach to anaerobic bioreduction in aerobic environments.

Synergistic biosorption and bioprecipitation strategy for Shewanella putrefaciens and Kocuria sp. to immobilizing U(VI) from aqueous solution under aerobic conditions

2019 Spring National Meeting

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