Chelating Effect of Siderophore Desferrioxamine-B on Uranyl Biomineralization Mediated by .

In contaminated water and soil, little is known about the role and mechanism of the biometabolic molecule siderophore desferrioxamine-B (DFO) in the biogeochemical cycle of uranium due to complicated coordination and reaction networks. Here, a joint experimental and quantum chemical investigation is carried out to probe the biomineralization of uranyl (UO, referred to as U(VI) hereafter) induced by (abbreviated as ) in the presence of DFO and Fe ion. The results show that the production of mineralized solids {hydrogen-uranium mica [H(UO)(PO)·8HO]} via binding with UO is inhibited by DFO, which can both chelate preferentially UO to form a U(VI)-DFO complex in solution and seize it from U(VI)-biominerals upon solvation. However, with Fe ion introduced, the strong specificity of DFO binding with Fe causes re-emergence of biomineralization of UO {bassetite [Fe(UO)(PO)·8(HO)]} by , owing to competitive complexation between Fe and UO for DFO. As DFO possesses three hydroxamic functional groups, it forms hexadentate coordination with Fe and UO ions via these functional groups. The stability of the Fe-DFO complex is much higher than that of U(VI)-DFO, resulting in some DFO-released UO to be remobilized by . Our finding not only adds to the understanding of the fate of toxic U(VI)-containing substances in the environment and biogeochemical cycles in the future but also suggests the promising potential of utilizing functionalized DFO ligands for uranium processing.