生物质稳定的零价铁处理水体中六价铬的性能与作用机制

With the boom development of industry and economy, Cr (VI) is widely detected in the aquatic system. Cr (VI) anions are highly toxic and caused both short and long term adverse effects. In recent years, nanoscale zero-valent iron (nZVI), on account of desired activities and highly effective for the removal/degradation of a wide range of contaminants, emerged as one of the hotspots in the field of environment remediation. However, due to large specific surface area and magnetic interactions, the existing nZVI tend to grow rapidly to micrometer or millimeter scale particles, thereby diminishing their reactivity and mobility. Therefore, high cost, agglomeration, and the unsatisfactory dispersity in aqueous solution are the major challenges for the nZVI used in environmental remediation. This project aims at the synthesis of size-controlled, biogenic Fe nanoparticles (NPs) through bioreduction by plant extracts conducted at room temperature, and their performance for the removal of Cr (VI) from aqueous solution. Methods to regulate the size and size distribution, to improve dispersity and stability of as-synthesized nZVI, will be investigated. Factors influencing the removal of Cr(VI) and the mobility will be also discussed. Roles of biomass in the formation of Fe NPs and hexavalent Chromium degradation will be revealed. Moreover, the reaction kinetics and reduction mechanism of Cr (VI) in surface water will be explored. This project will provide essential knowledge to fabricate nZVI with low cost, better performance to remove Cr(VI) and excellent stability through ecofriendly route, in pursuit of high-efficient, sustainable degradation of hexavalent Chromium in the polluted water.

随着工业和经济的快速发展，我国水体环境受到严重污染，其中Cr(VI)以其较大的毒害作用引发了一系列负面效应。纳米零价铁（nZVI）由于高反应活性、可修复多种污染物等优点成为目前环境污染修复领域中的热点之一。本项目针对目前nZVI合成成本高、不易控制，应用中稳定性与分散性不理想等问题，以植物提取液在常温下可控合成nZVI，并将这种生物质稳定的nZVI应用于水环境中Cr(VI)的去除。项目旨在掌握生物质稳定的nZVI的粒径和粒径分布的调控方法；获得改善其稳定性和分散性的有效手段；考察该材料对Cr(VI) 的去除性能及迁移性能；研究Cr(VI)去除反应的动力学；阐明生物质稳定nZVI的形成过程及生物质在降解中的作用；分析nZVI去除Cr(VI)的反应机理，为发展低成本、环境友好的、具有较高活性和稳定性的nZVI的制备方法，实现可持续化降解水体中Cr(VI)提供必要的理论基础。

纳米铁材料由于其较高的反应活性和可处理污染物的多样性在环境修复领域备受关注。但是，纳米铁在应用过程中存在易被氧化、稳定性差等问题，各种改性技术往往会带来合成成本的提高。本项目将生物还原的物理化学原理引入到纳米铁的制备与应用过程中，以植物提取液在常温下合成纳米铁，并将这种生物质稳定的纳米铁应用于水环境中Cr(VI)的去除。课题围绕该纳米铁制备与应用过程中的关键科学问题展开研究，建立了生物质提取液中活性成分与其Fe还原能力的关联；阐明了生物质在纳米铁形成过程中的作用；对生物质稳定纳米铁的各项物化性质系统进行了系统表征；研究了该材料对水相中Cr(VI) 的去除性能、稳定性及迁移性能；进而探讨了生物质稳定的纳米铁还原Cr(VI)的动力学及作用机制。项目研究为发展低成本、环境友好的、具有较高活性和稳定性的纳米铁的制备方法，实现可持续化降解水环境中Cr(VI)提供了必要的理论基础。项目在研期间共发表论文13篇，培养硕士研究生3名。