零价铁较广泛应用于受污染地下水修复和工业废水处理中。当用于污染物的还原去除时，零价铁大部分消耗于与氧气（有氧条件下）、氢离子或水的副反应，对目标污染物的电子选择性低，导致了零价铁的极大浪费、降低了技术的经济性。鉴于提高零价铁还原除污染过程中电子选择性的迫切需求，拟选择常规方法难以去除但可被零价铁还原去除的六价硒作为目标污染物，系统考察不同反应条件下硫化、弱磁场、外加亚铁或强氧化剂四种典型的活化方法对零价铁还原除六价硒过程反应速率及电子选择性的影响，原位监测反应过程中pH、ORP、DO等指标的变化并研究零价铁的腐蚀演变过程及其对六价硒的还原机制，剖析零价铁去除六价硒的速率常数与其对六价硒的电子选择性之间的关系，甄别影响零价铁还原除六价硒的电子选择性的关键因子和反应机制，进而研发提升零价铁还原除六价硒电子选择性的新方法。本课题的研究结果将为零价铁技术的进一步推广应用提供坚实的理论和技术支持。

Zero-valent iron (ZVI) has been widely used in groundwater remediation and industrial wastewater treatment. Most of ZVI is consumed in the undesired reactions with O2 (under oxic conditions), H+ and H2O when ZVI is employed to reduce contaminants, which results in the waste of ZVI and increases the burden of sludge disposal. Therefore, it is of great significance to improve the electron selectivity of ZVI toward the target contaminant. However, the critical factors affecting the electron selectivity of ZVI keeps unknown. This project selects Se(VI), which is difficult to be removed by coagulation and adsorption but can be removed by ZVI via reduction, as target contaminant, and will investigate the influence of sulfidation treatment, weak magnetic field, Fe2+ and strong oxidant on the kinetics of Se(VI) reduction by ZVI and the corresponding electron selectivity under various reaction conditions. The change of pH, ORP, and DO as well as the ZVI corrosion process and Se(VI) removal mechanisms will be monitored in-situ. The relationship between the rate constant of Se(VI) reduction by ZVI and the corresponding electron selectivity will be explored and the critical factors influencing the electron selectivity of ZVI toward Se(VI) will be identified. In addition, the new method of increasing the electron selectivity of ZVI toward Se(VI) will be proposed and experimentally verified. The results of this project will provide solid theoretical and technical support for the application of ZVI in real practice.