Enhanced U(VI) bioreduction by alginate-immobilized uranium-reducing bacteria in the presence of carbon nanotubes and anthraquinone-2,6-disulfonate |
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| Authors: | Weida Wang Yali Feng Xinhua Tang Haoran Li Zhuwei Du Aifei Yi and Xu Zhang |
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| Institution: | Civil and Environmental Engineering School, University of Science and Technology Beijing, Beijing 100083, China;National Key State Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China,Civil and Environmental Engineering School, University of Science and Technology Beijing, Beijing 100083, China,National University of Singapore, Department of Civil and Environmental Engineering, Centre forWater Research, Singapore 117576, Singapore,National Key State Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China,National Key State Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China,Civil and Environmental Engineering School, University of Science and Technology Beijing, Beijing 100083, China and Civil and Environmental Engineering School, University of Science and Technology Beijing, Beijing 100083, China |
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| Abstract: | Uranium-reducing bacteria were immobilized with sodium alginate, anthraquinone-2, 6-disulfonate (AQDS), and carbon nanotubes (CNTs). The effects of different AQDS-CNTs contents, U(IV) concentrations, and metal ions on U(IV) reduction by immobilized beads were examined. Over 97.5% U(VI) (20 mg/L) was removed in 8 hr when the beads were added to 0.7% AQDS-CNTs, which was higher than that without AQDS-CNTs. This result may be attributed to the enhanced electron transfer by AQDS and CNTs. The reduction of U(VI) occurred at initial U(VI) concentrations of 10 to 100 mg/L and increased with increasing AQDS-CNT content from 0.1% to 1%. The presence of Fe(III), Cu(II) and Mn(II) slightly increased U(VI) reduction, whereas Cr(VI), Ni(II), Pb(II), and Zn(II) significantly inhibited U(VI) reduction. After eight successive incubation-washing cycles or 8 hr of retention time (HRT) for 48 hr of continuous operation, the removal efficiency of uranium was above 90% and 92%, respectively. The results indicate that the AQDS-CNT/AL/cell beads are suitable for the treatment of uranium-containing wastewaters. |
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| Keywords: | Uranium Carbon nanotubes (CNTs) Redox mediator Anthraquinone-2 6-disulfonate (AQDS) Immobilization |
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