Leucobacter对Cr(Ⅵ)的还原及其还原产物的成分分析

Bio-reduction of Cr(Ⅵ) by Leucobacter and element analysis of reduction products

考察Leucobacter spp.Ch1的细胞在生长状态和休眠状态对六价铬的还原;运用SEM和TEM对还原前后Leucobacter的形态进行观察,并利用EDAX和EPR分析还原产物的成分。研究结果表明:在好氧条件下,生长的细菌还原250 mg/L Cr(Ⅵ)需5 h,细胞悬液需45 min;在厌氧条件下,休眠细胞还原能力较强,而接种于培养基的细菌无还原能力;还原反应的产物主要附着在细菌的末端,表明反应发生于细胞表面;反应产物中Cr的含量为28.2%,表明三价铬以Cr(OH)3沉淀的形式存在。

Chromate reduction ability ofLeucobacter spp. Chl was studied with its growing cells and resting cells. SEM and TEM were used to observe the shape of bacterial cell before and after Cr（Ⅵ） reduction. EDAX and EPR were employed to determine the composition of the reduction products. The results show that it takes 5 h to reduce 250 mg/L Cr（Ⅵ） with growing cells and 45 min with resting cells under aerobic conditions. Effective reduction ability is also found in resting cells rather than in growing cells under anaerobic conditions. Reaction product adheres to the terminal of bacterial cells, which indicates that chromate reduction takes place on the surface of Chl cells. Reduction product contains 28.2% of Cr and it is determined as trivalent chromium in the form of Cr（OH）3 precipitate.