A synergistic biosorption and biomineralization strategy for Kocuria sp. to immobilizing U(VI) from aqueous solution

In order to investigate the immobilization ways of uranium (U(VI)) on Kocuria sp., we investigated the interaction behavior under different conditions by batch experiment. U(VI) products on Kocuria sp. 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 illustrated characteristic UO22+ peaks after U(VI) interaction with Kocuria sp. According to FTIR analysis, in addition to PO43− groups, CO, OH, COOH groups might play important roles in complexation with U(VI). The biomineralization process of U(VI) on Kocuria sp. required longer time than sorption process, indicating that biomineralization was induced by the biosorption process. Our findings highlight the synergistic biosorption and biomineralization process of Kocuria sp. for U(VI) immobilization, which concentrated U(VI) on the cell surface via fast biosorption by providing nucleation sites for the precipitation to insoluble minerals, while the formation of U(VI) biomineral led to the relatively permanent immobilization of U(VI), and then emphasize the important roles of phosphate which are of significance in predicting the U(VI) immobilization properties.