生物炭介导希瓦氏菌还原FeOOH降解地下水氯代有机物污染机理

The applications of nanoscale zero-valent iron (nZVI) for degradation of contaminants have been received widespread attention due to its controllable particle size, high reactivity and abundant reactive surface sites. However, nZVI has a strong tendency to surface oxided which blocks the surface active sites and decreases the reaction rate. It has been reported that surface film of oxidized minerals often formed on the surface of nZVI. The negative effect of iron corrosion products on the reactivity of ZVI has become a major issue in the further development of nZVI technology. It is therefore significant to develop an method able to re-activation the aged nZVI to enhance removal efficiency of contaminants. In this work, based on biochar which has large specific surface area and high surface energy, and contains many functional groups, it could be used as electron shuttle to increase the electron transfer rate from iron reducing bacteria to aged ZVI. The aim is to establish the aged ZVI, biochar and iron reducing bacteria coupled system. chlorinated organic was selected as a representative target contaminants. The mechanism of biochar in reductive dechlorination of PCP by aged ZVI was discussed, and the mechanism of reduction dechlorination of target pollutants by system was also investigated. This study establish a system that enhance the activity of aged ZVI. It provides a theoretical basis for the popularization and application of zero valent iron technology in environmental remediation, and provides technical support for developing new groundwater remediation materials.

地下水环境普遍受到氯代有机物污染，对生态环境和人体健康造成严重危害，亟需进行修复；纳米零价铁是最具潜力的原位修复材料之一，但在地下水环境中容易发生钝化，生成铁氧化物覆盖在纳米零价铁颗粒表面，阻止零价铁与污染物反应。为提高钝化纳米零价铁的反应活性，本项目提出采用生物炭作为电子穿梭体介导铁氧化物与铁还原菌的电子传递过程，基于生物炭多孔结构可以将微生物和氯代有机物吸附于表面，形成局部富集，构建生物炭负载钝化纳米零价铁和铁还原菌耦合体系，研究还原脱氯转化氯代有机污染物的特性，采用电化学手段阐明生物炭介导希瓦氏菌还原钝化零价铁强化氯代有机物降解的机理；揭示铁还原菌氧化过程产生的电子通过呼吸链传递给生物炭过程，生物炭将电子传递给钝化零价铁的表面的FeOOH，使其还原成吸附态Fe(II)，提高钝化零价铁的反应活性，为阐明耦合体系强化地下水氯代有机污染物降解的生物地球化学过程及其环境响应机制提供科学依据。