NOM介导零价铁活化分子氧去除污水中难降解毒害性有机物的作用机理及强化方法

How to safely and efficiently remove refractory toxic organic pollutants (RTOPs) from sewage has become the primary problem restricting the reuse of municipal sewage. Zero-valent iron (ZVI) can reductively activate molecular oxygen to generate reactive oxygen species for oxidation or even mineralization of RTOPs. However, the low removal efficiency of this technology has posed potential limitation to its practical application. Natural organic matter (NOM), as a heterogeneous mixture of polyfunctional organic ligands ubiquitous in aqueous environments, plays an important role in determining the ability of ZVI to activate molecular oxygen, but the related mechanism is still unclear. Taking nonylphenol, one kind of EDCs frequently detected in the effluent of sewage treatment plants, as the target pollutant, the objectives of this project are to (i) investigate the effect of different NOM on RTOPs degradation efficiency and pathway by molecular oxygen activation with both nano- and micro-size ZVI, and reveal the correlation between NOM characteristics and RTOPs degradation efficiency; (ii) explore the mechanism of RTOPs removal mediated by NOM in the ZVI/O2 system, via comparing the kinetic process of reactive oxygen species, transformation of iron speciation, micro-morphology of the ZVI surface in the presence and absence of NOM, analyzing the dynamic distribution and formation of NOM during the oxygen activation process, understanding the complexing ability of NOM with ferrous or ferric ions; (iii) establish a new NOM-mediated enhancement method for degradation of RTOPs in ZVI-O2 system on the basis of above research, and evaluate its application prospect by operating long-term column reactor. This project will provide the scientific and technical support for the application of molecular oxygen activation technology with ZVI in tertiary treatment of municipal sewage.

如何安全高效去除污水中难降解毒害性有机物已成为制约城市污水回用的首要难题。零价铁（ZVI）可以活化O2分子产生活性氧物质降解毒害性有机物，然而去除效能低是其应用的重要障碍。另一方面，水体中广泛存在的天然有机质（NOM）会影响ZVI活化O2的能力，但相关机制尚不明确。针对上述问题，本项目拟以污水厂出水中频繁检出的壬基酚类EDCs为目标污染物，系统考察NOM对纳米和微米级ZVI活化O2降解毒害性有机物的影响规律；探索在NOM作用下ZVI活化O2产活性氧物质的动力学过程，揭示NOM对ZVI物化特性的作用规律，解析NOM分布与赋存形态的动态变化，深入剖析NOM介导ZVI活化O2降解毒害性污染物的作用机制；在以上研究基础上，建立NOM介导ZVI-O2体系降解毒害性有机物的强化新方法，并通过长期柱实验评估其应用前景。该项目的研究结果将为ZVI活化分子氧技术应用于城市污水深度处理提供科学依据与技术支撑。

水体中广泛存在的天然有机质（NOM）会影响ZVI在有氧条件下的活性，但相关规律及作用机理尚不明确。本项目解析了大分子有机质在有氧条件下促进零价铁（ZVI）腐蚀、活性物种生成、有机污染物降解的作用机理，阐明了大分子有机质结构特性、零价铁尺寸对有机污染物去除效率的影响规律及作用机制；探明了天然有机质特性和ZVI在有氧条件下降解有机污染物之间的构效关系，明确了有机质的芳香度、氨基基团含量、亲疏水性影响ZVI界面行为的重要性；揭示了在有氧条件下有机质对微米到纳米级ZVI的反应活性将由促进转为抑制这一规律，深度解析了有机质对不同尺寸ZVI反应界面的调控机理；建立了有机质介导铁基体系降解毒害性有机质的强化方法，明确了有机质对活性氧物种的调控规律。本项目的研究结果为实现以最小成本、不引入二次污染来提高零价铁反应活性提供了新思路。