被撤回的出版物: Effects of Bacillus subtilis on the reduction of U(VI) by nano-Fe0 (Retracted article. See vol. 280, pg. 457, 2020)

The effects of Bacillus subtilis (B. subtilis, a typical model bacterium) on the reduction of U(VI) by nanoscale zero-valent iron (nano-Fe-0) were investigated using batch techniques. The reaction products were analysed using spectroscopic techniques, and a kinetics model was developed to elucidate the mechanisms of U(VI) reduction by nano-Fe-0. The presence of B. subtilis enhanced the U(VI) sorption rate at pH 3.5-9.5 but inhibited the reduction rate of U(VI) to U(IV) at pH > 4.5. According to the FTIR and XRD analysis, the reduction of U(VI) to U(IV) was inhibited due to the formation of inner-sphere surface complexes between the oxygen-containing functional groups of B. subtilis or extracellular polymeric substances with the Fe(II)/Fe(III) generated by nano-Fe-0, which blocked electron transport from the Fe-0 core to U(VI). Based on the EXAFS analysis, a fitting of U-Fe shell at similar to 3.44 angstrom revealed inner-sphere bidentate complexes between uranyl and the oxide film of nano-Fe-0. For the nano-Fe-0 + B. subtilis system, the U-Fe shell (at similar to 3.44 angstrom) and the U-C/P shell (at similar to 2.90 angstrom) further indicated the formation of inner-sphere surface complexes. The kinetics model supported that U(VI) reduction was triggered by U(VI) sorption on the oxide shell of nano-Fe-0. The XPS and XANES analyses showed that reductive precipitation was the main mechanism of U(VI) removal by nano-Fe-0, whereas the sorption process dominated the removal of U(VI) in the presence of B. subtilis, which was further demonstrated by TEM images. (C) 2015 Elsevier Ltd. All rights reserved.