异化铁还原细菌LQ25还原重金属Cr (VI)的特性研究

Characteristics of Cr(VI) reduction by dissimilatory Fe(III)-reducing bacterium LQ25

摘要:

[背景] 异化铁还原细菌能够在还原Fe （III）的同时将毒性较大的Cr （VI）还原成毒性较小的Cr （III），解决铬污染的问题。[目的] 基于丁酸梭菌（Clostridium butyricum） LQ25异化铁还原过程制备生物磁铁矿，开展异化铁还原细菌还原Cr （VI）的特性研究。[方法] 构建以氢氧化铁为电子受体和葡萄糖为电子供体的异化铁培养体系。菌株LQ25培养结束时制备生物磁铁矿。设置不同初始Cr （VI）浓度（5、10、15、25和30 mg/L），分别测定菌株LQ25对Cr （VI）还原效率以及生物磁铁矿对Cr （VI）的还原效率。[结果] 菌株LQ25在设置的Cr （VI）浓度范围内都能良好生长。当Cr （VI）浓度为15 mg/L时，在异化铁培养条件下，菌株LQ25对Cr （VI）的还原率为63.45%±5.13%，生物磁铁矿对Cr （VI）的还原率为87.73%±9.12%，相比菌株还原Cr （VI）的效率提高38%。pH变化能影响生物磁铁矿对Cr （VI）的还原率，当pH 2.0时，生物磁铁矿对Cr （VI）的还原率最高，几乎达到100%。电子显微镜观察发现生物磁铁矿表面有许多孔隙，X-射线衍射图谱显示生物磁铁矿中Fe （II）的存在形式是Fe （OH）₂。[结论] 基于异化铁还原细菌制备生物磁铁矿可用于还原Cr （VI），这是一种有效去除Cr （VI）的途径。

Abstract:

[Background] Reducing Cr(VI) to Cr(III) by dissimilatory Fe(III)-reducing bacteria is an important way for remediation of chromium pollution. [Objective] This work examined the characteristics of Cr(VI) reduction by biogenic magnetite particles using dissimilatory Fe(III)-reducing bacterium Clostridium butyricum LQ25. [Methods] Strain LQ25 was grown under Fe(III)-reducing conditions and was used to produce biogenic magnetite particles using glucose as electron donors and insoluble iron hydroxide as the electron acceptor. The efficiencies of Cr(VI) reduction under Fe(III)-reducing conditions were examined with different Cr(VI) concentrations (5, 10, 15, 25 and 30 mg/L) added to the medium respectively. [Results] In the presence of iron hydroxide, strain LQ25 could grow within the set Cr(VI) concentration range with Cr(VI) reduction efficiency of 63.45%±5.13% at Cr(VI) concentration of 15 mg/L. When adding biogenic magnetite particles, Cr(VI) reduction efficiency of 87.73%±9.12% was obtained, increased by 38% compared with the control. Cr(VI) reduction by biogenic magnetite particles was decreased obviously with increasing pH solutions from 2.0 to 8.0. At pH 2.0, the reduction rate of Cr(VI) by biogenic magnetite particles was the highest, almost 100%. There were many pores on the surface of biogenic magnetite particles under scanning electron microscope. Biogenic magnetite particles showed XRD peaks include Fe(II) existed in the form of Fe(OH)₂.[Conclusion] These results indicated that dissimilatory Fe(III)-reducing bacteria and the biogenic magnetite particles could reduce Cr(VI), which will provide the evidence for the application of dissimilatory Fe(III)-reducing bacteria into the reduction of Cr(VI).