电活性生物膜介导Cu^(2+)生物还原的试验研究

Microbial Reduction of Cu^(2+) Mediated by Electroactive Biofilms

电活性生物膜形成、胞外电子传递机制以及环境效应研究已成为环境领域关注的热点.通过在碳毡上富集形成生物膜,采用电化学方法对生物膜的电活性进行了表征,对电活性生物膜直接介导Cu2+的还原转化进行了初探.利用扫描电子显微镜(SEM)、能谱分析仪(EDS)、X射线光电子能谱(XPS)对Cu元素的形貌、含量以及价态进行分析,结果表明电活性生物膜能够利用乙酸作为电子供体,Cu2+作为电子受体,将Cu2+还原转化成Cu或Cu+.同时,通过激光共聚焦显微镜(LSCM)观察Cu2+对微生物的影响,结果显示Cu2+对微生物有明显的毒害作用,所以电活性生物膜介导Cu2+的转化只能在较低的铜离子浓度下进行.本研究结果将为电活性生物膜应用于环境中铜离子的固定和回收提供理论依据.

The formation,electron transfer mechanism and environmental effect of electrochemically active biofilms( EABs) have become a hot research topic in environmental science. In this study,bacteria were enriched on a carbon felt to form an EAB under controlled potential conditions. The electrochemical properties of the EAB were evaluated with electrochemical methods. The process of copper reduction and transformation mediated by the EAB was revealed. Analytical techniques such as scanning electron microscopy( SEM),energy dispersive spectroscopy( EDS) and X-ray photoelectron spectroscopy( XPS) were used to examine the morphology, content and state of copper in the biofilm. The results showed that the EAB could utilize acetate as electron donor to produce electrons and Cu2 +was reduced to Cu or Cu+. Laser scanning confocal microscope( LSCM) was employed to probe the toxic effects of Cu2 +on the EAB. Copper toxicity on the microbes was reduced in the presence of acetate because of the reduction transformation of Cu2 +to less toxic Cu or Cu+. The results from this study are expected to be instructive for using EABs to stabilize and recover copper from coppercontaminated environments.