(1. 南華大學(xué) 污染控制與資源化技術(shù)湖南省高校重點實驗室，衡陽 421001；
2. 南華大學(xué) 鈾礦冶生物技術(shù)國防重點學(xué)科實驗室，衡陽 421001)
摘 要: 采用現(xiàn)代分析方法探討零價鐵(ZVI)與奧奈達希瓦氏菌(S. oneidensis)MR-1還原U(Ⅵ)的效果與機制。結(jié)果表明：ZVI與S. oneidensis均能夠還原U(Ⅵ)；在厭氧條件下，ZVI與S. oneidensis還原U(Ⅵ)存在協(xié)同作用。當(dāng)pH為7、溫度為30 ℃、U(Ⅵ)的初始濃度為20 mg/L、ZVI的投加量為1.0 g/L時，24 h S. oneidensis對U(Ⅵ)還原率達到96.9%；在0.5~2.0 g/L范圍內(nèi)，U(Ⅵ)的還原率隨ZVI投量的增加而上升；在U(Ⅵ)初始濃度5.0~50.0 mg/L內(nèi)，U(Ⅵ)的還原率與其濃度正相關(guān)。ZVI、Fe3O4和Fe2O3均能明顯促進U(Ⅵ)的還原，而可溶態(tài)的Fe(Ⅲ)對U(Ⅵ)的還原具有明顯的抑制作用。其他離子Cu2+、Ca2+、Mn2+和NO3-對U(Ⅵ)的還原存在抑制作用，以Cu2+的影響最大，Ca2+的影響次之，SO42-對U(Ⅵ)的還原影響較小。XPS分析結(jié)果表明，ZVI表面吸附和沉積了U(Ⅵ)和U(Ⅳ)兩種價態(tài)的U元素，反應(yīng)后的鈾大部分形成了穩(wěn)定的UO2。
關(guān)鍵字: 零價鐵；U(Ⅵ)；奧奈達希瓦氏菌；XPS分析
（1. Hunan Provincial Key Laboratory of Pollution Control and Resources Reuse Technology,
University of South China, Hengyang 421001, China;
2. Key Discipline Laboratory for National Defence for Biotechnology in Uranium Mining and Hydrometallurgy,
University of South China, Hengyang 421001, China）
Abstract:The effects and mechanism of U(Ⅵ) reduction by Shewanella oneidensis (S.oneidensis) MR-1 with zero-valent iron(ZVI) were evaluated. The results show that either ZVI or bacteria can reduce U(Ⅵ) in the solution, and under anaerobic conditions, a cooperative action of ZVI and the bacteria S.oneidensis is observed in reducing process of U(Ⅵ). Under condition of pH 7.0, temperature 30 ℃, the initial concentration of U (Ⅵ) 20 mg/L and ZVI addition 1.0 g/L, the reduction rate of U(Ⅵ) reaches 96.9% by S.oneidensis reduction for 24 h. The reduction rate of U(Ⅵ) is improved with increasing amount of ZVI in the range of 0.5-2.0 g/L, and the reduction rate of U(Ⅵ) is positive correlated with its initial concentration in the range of 5.0-50.0 mg/L. Fe3O4, Fe2O3 and ZVI are effective accelerators for bioreduction of U(Ⅵ), and soluble Fe(Ⅲ) can remarkably inhibit U(Ⅵ) bioreduction. The other coexistence ions, such as Cu2+, Ca2+, Mn2+ and NO3-, show a remarkable negative effect on U(Ⅵ) reduction, and among these ions, the negative effect of Cu2+ is the greatest and that of Ca2+ is the second. SO42- has less influence on U(Ⅵ) bioreduction. XPS results indicate the deposition of U element are in forms of U(Ⅵ) and U(Ⅳ) on iron filings surface, and the reduction product U(Ⅳ) is most likely to be in the form of UO2.
Key words: zero-valent iron ( ZVI); U(Ⅵ); Shewanella oneidensis MR-1; XPS analysis
