有氧条件下硫化零价铁还原去除水中Cr(VI)反应机制研究

Zerovalent iron (ZVI), a simple but amazingly versatile material, has been successfully applied for the remediation of groundwater and the industrial wastewater improvement. However, when ZVI is used to reduce pollutants, most of electrons donated by ZVI are consumed in side reactions with oxygen, hydrion or water under aerobic condition, and the electronic efficiency of ZVI towards the target pollutants is decreased, which leads to a great waste of ZVI. This project is proposed by using in situ X-ray absorption fine structure spectroscopy (XAFS), X-ray photoelectron spectroscopy (XPS) characterization technique. It was discussed by adjusting the sulfidation method, sulfidation agent and the molar ratio of S/Fe under aerobic conditions, for zerovalent iron removal of Cr (VI) towards improving reactivity. From the perspective of microstructure under real system, the mechanisms of sulfidation involved the improved reactivity and electron efficiency of ZVI is cleared. This project will provide a solid theoretical and technical support for the environmental application of S-ZVI technology.

作为一种环境友好、价格低廉的水处理药剂，零价铁（ZVI）已在受污染地下水修复和工业废水处理中得到了广泛应用。然而，当零价铁应用于污染物的还原去除时，大部分消耗于与氧气、氢离子或水的副反应，而对目标污染物的电子效率较低，导致了零价铁的极大浪费。本项目拟采用有氧体系为反应背景，利用原位X射线吸收精细结构谱（XAFS）、光电子能谱（XPS）表征技术，通过调整硫化方法、硫化药剂种类以及S/Fe摩尔比对零价铁去除水中Cr(VI)的反应活性改善，从微观结构角度探讨真实体系下硫化对零价铁还原去除Cr(VI)反应活性以及电子效率的影响规律，明晰硫化作用零价铁除污染效能的作用机制，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。

针对硫化能提高Fe0还原去除污染物过程中反应活性和电子效率的潜能及其作用机制未知的现状，以及硫化Fe0在水处理中的应用前景，本项目通过比较有氧条件下不同硫化条件合成的硫化Fe0反应活性，确定最优的硫化条件，考察反应条件对硫化零价铁去除Cr(VI)的动力学影响，以及在有氧条件下硫化对零价铁去除Cr(VI)电子效率的影响，并利用同步辐射XAFS表征手段、电化学分析实验探究在硫化Fe0去除Cr(VI)过程中硫的价态形态的转化，明确硫在反应过程中所起的作用，揭示硫化影响Fe0还原去除Cr(VI)反应活性和电子效率的微观反应机制。该课题的研究结果将为硫化Fe0还原去除无机含氧酸根金属离子过程电子效率的提高提供借鉴作用，还将为Fe0技术在地下水修复和水污染控制领域的推广应用提供坚实的理论和技术支持，实现Fe0的有效利用，减少环境污染。