共存金属离子对Fe^0-奥奈达希瓦氏菌协同还原U(Ⅵ)的影响

Influence of coexistent metal ions on reduction of U(Ⅵ)by Shewanella oneidensis with Fe^0

研究Fe0-奥奈达希瓦氏菌(Shewanella oneidensis,S.oneidensis)(MR-1)协同还原去除水相中的U(Ⅵ)时,共存金属离子Cu^(2+)、Ca2+、Mn2+和Zn2+存在时分别对U(Ⅵ)还原效果的影响。结果表明:在10.0~50.0 mg·L-1范围内,共存Ca2+和Zn2+对U(Ⅵ)的还原有一定的抑制,且影响大小与其浓度呈正相关,共存Cu^(2+)几乎完全抑制了U(VI)的还原;在Cu^(2+)浓度低于5.0 mg·L-1时,其对U(VI)的还原存在一定程度的抑制。在Fe0-S.oneidensis还原U(Ⅵ)的初期,10.0~50.0 mg·L-1的Mn2+对U(Ⅵ)的还原有抑制作用,18 h后,Mn2+对U(Ⅵ)的还原基本没有影响,且高浓度的Mn2+对U(Ⅵ)的还原有微弱的促进作用。共存金属离子对六价铀还原酶还原U(Ⅵ)的影响研究表明,Cu^(2+)、Ca2+和Zn2+对U(Ⅵ)还原酶的活性有一定的抑制作用,其中Cu^(2+)的最明显,而Mn2+对还原酶的活性有微弱的催化作用。

Microbial reduction technology using Shewanella oneidensis with Fe0 was employed to treat U （VI） in wastewater. Anaerobic experiments were conducted to evaluate the influence of the coexistent metal ions, such as Cu2＋, Ca/＋ , Mn2＋, and Zn2＋ , on the reductive removal rate of U（ VI ）. The results demonstrated that the reduction of U（VI） was significantly inhibited when the concentration of Cu2＋ was 10.0 to 50.0 mg · L- 1. When the concentration of Cu2 ＋ ions was less than 5.0 mg · L-1 , the reduction of U （ VI ） was only slightly inhibited. The coexistence of Ca2 ＋ and Zn2 ＋ showed a remarkable negative effect on U（VI） reduction, and the effect of these ions on the reduction of U （ VI ） was positively correlated with their concentration. The coexistence of Mn2 ＋ can caused the inhibition of the U（VI） reduction in the early reaction phase at a Mn2 ＋ concentration of 10.0 to 50.0 mg · L-1. However, little influence was found on the reduction of U（VI） when the process lasted more than 18 hours. A higher concentration of Mn2＋ could promote U（VI） reduction slightly. The results of the reduction of U（ VI ） with different metal ions indicate that, as a catalyst, Mn2 ＋ has little influence on the activity of the U （ VI ） reductase, but Cu2 ＋ , Ca2 ＋ , and Zn2 ＋could inhibit the enzyme activity, with Cu2＋being the most prominent in this regard.