纳米零价铁基材料去除水中硝酸盐污染的研究进展

Review of Nanoscale Zero Valent Iron-based Materials and Their Application in the Removal of Aqueous Nitrate Pollution

地下水和地表水中的硝酸盐污染成为一个日益严重的环境问题,通过经济有效的办法对硝酸盐污染进行控制或处理,甚至实现完全无害化,是非常必要且迫切的。纳米零价铁作为一种典型的工程纳米材料,在硝酸盐污染环境修复中有巨大的应用潜力。以纳米零价铁技术在硝酸根还原中的应用发展作为依据,该领域当前主要的研究工作集中于:(1)通过对纳米零价铁颗粒合成方法的探索和改进,提高其对高浓度硝酸盐废水的耐冲击能力,或与其他修复处理技术联用,增强其在原位修复中的适用性等;(2)研究环境条件(包括反应温度、溶解氧浓度、溶液初始pH,以及环境中其他竞争离子等)对纳米零价铁还原硝酸盐的影响规律,为该技术的工业推广提供理论支撑。然而,总结这些研究工作后发现该技术在向实用化进程中仍存在一些难点问题,尤其是零价铁技术使用寿命较短,硝酸根在体系内传质和吸附受限,产物(氮气)选择性低等。为此,在纳米零价铁材料的基础上,通过对其进行功能化改性,进而合成纳米铁基复合材料,作为更先进的技术替代。本文从负载型、双金属型、表面改性型几个方面对纳米铁基复合材料进行了归纳整理,重点阐述了不同复合体系在水中硝酸盐污染去除中展示出的优异于纯纳米零价铁体系的多种性能,揭示纳米铁基复合材料促进机理和影响硝酸根还原能效的因素。最后,对纳米零价铁基材料修复水中硝酸根污染技术目前尚需要解决的问题和未来的发展方向进行了思考和展望。

A queous nitrate(NO_(3)-)contamination is an ubiquitous environmental problem because of the extensive application of the relevant chemicals;the remediation of water polluted by nitrate via economic and effective methods,evenly realizing complete harmlessness is crucial.Nanoscale zero-valent iron(nZVI)is a typical engineered nanomaterial that is potentially used in environmental remediation of nitrate pollution.In this paper,based on the application and development of nZVI technology in nitrate reduction,the prior studies mainly focus on the following:(1)improving its synthesis method or combining with other remediation techniques to improve its efficiency in in-situ remediation and enhance its resilience towards high concentration nitrate wastewater;(2)investigating the effects of environmental conditions including temperature,dissolved oxygen,solution pH,and competitive coexisting ions,to guide its practical applications.Although nZVI technology possesses remarkable potential in NO3-conversion,some difficulties remain,especially the short lifetime,limited mass transfer and adsorption capacity,and low selectivity towards nitrogen as a final product.These hinder the large-scale practical application of the technology.Therefore,functionalized nZVI-based materials,upon suitable modification,have gradually become promising substitutes for bare nZVI.Herein,these modified materials are classified into three types,namely the supported,bimetallic,and the surface-modification system,especially emphasizing their advantages as compared with bare nZVI and revealing its promotion mechanism and factors affecting nitrate reduction energy efficiency.Finally,the existing problems to be addressed are identified,and future objectives and research areas worthy of exploration in the field of nZVI-based remediation technology are proposed.