Effects of Citrate, NTA, and EDTA on the Reduction of U(VI) by Shewanella putrefaciens
Effects of Citrate, NTA, and EDTA on the Reduction of U(VI) by Shewanella putrefaciens
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DOI：
10.1080/01490450903456764
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发表时间：
2010-04
影响因子：
2.3
通讯作者：
Yoshinori Suzuki;Kazuya Tanaka;N. Kozai;T. Ohnuki
中科院分区：
文献类型：
--
作者：
Yoshinori Suzuki;Kazuya Tanaka;N. Kozai;T. Ohnuki
在柠檬酸盐、NTA和EDTA存在的情况下，研究了腐坏希瓦氏菌对U（VI）的还原，以阐明强络合剂对生物还原的影响。铀（VI）和乳酸分别作为唯一的电子受体和给体，在30℃厌氧条件下，初始pH为7.0。在不含柠檬酸盐、NTA和EDTA的对照培养基中，溶解U的浓度随着时间的推移而降低，并出现沉淀。x射线吸收近边结构分析表明，析出物中含有U（IV）。在柠檬酸盐、NTA或EDTA存在的情况下，溶解U的浓度几乎没有变化。紫外可见光谱显示，随着时间的推移，培养基中U（VI）种的浓度降低，U（IV）种的浓度升高。这些结果表明，强络合剂的存在通过形成可溶性的U(IV)-有机络合物抑制了UO2的生物还原性沉淀。在形成多核U(VI)-柠檬酸配合物的柠檬酸介质中，U（VI）的初始还原速率比在NTA和EDTA介质中慢得多。多核复合物的形成可能是腐坏葡萄球菌阻碍U（VI）还原的原因之一。结果表明，强络合剂的存在影响了U（IV）的化学形态和U（VI）的还原速率。
Reduction of U(VI) by Shewanella putrefaciens in the presence of citrate, NTA, and EDTA was examined to elucidate the effects of strong complexation agents on biological reduction. Uranium(VI) and lactic acid were supplied as the sole electron acceptor and donor, respectively, under anaerobic conditions at 30°C at initial pH 7.0. In the control medium containing no citrate, NTA, or EDTA, the concentration of dissolved U decreased with time and precipitates appeared. X-ray absorption near-edge structure analysis showed that the precipitates contained U(IV). In the presence of citrate, NTA, or EDTA, the concentrations of dissolved U scarcely changed. The UV-VIS spectra of the media showed that concentrations of U(VI) species decreased and those of U(IV) species increased with time. These results indicate that the presence of strong complexation agents inhibits biological reductive UO2 precipitation by forming soluble U(IV)-organic complexes. The initial reduction rate of U(VI) in the citrate medium in which polynuclear U(VI)-citrate complexes were formed was much slower than those in the NTA and EDTA media. Formation of the polynuclear complexes may be one of the reasons for retardation of the U(VI) reduction by S. putrefaciens. Our results indicate that the presence of strong complexation agents affects the chemical species of U(IV) and the reduction rate of U(VI).