原位再生硫酸根自由基的电催化氧化体系构建及其反应机制研究

The advanced oxidation technology based on sulfate radical has gained increasing attentions in water and wastewater treatment. However, there is no report on sulfate radical regeneration by sulfate supporting electrolyte which is widely used in the electrocatalytic system as well as the catalytic oxidation of organic pollutants with the electrochemical created sulfate radical. An electrocatalytic oxidation system based on in situ regeneration of sulfate radical would be valuable for study and have great potential in application since it can realize in situ generation and regeneration of sulfate radical and/or persulfate from sulfate anion, as well as circular utilization of activator for persulfate, Fe2+, during the organic pollutants degradation process. In the present project, the following works would be carried out. Firstly, the electrode materials would be prepared and optimized and the indirectly electrocatalytic process based on sulfate radical would be realized. Secondly, the factors affecting sulfate radical regeneration would be investigated; the effectiveness of catalytic oxidation of organic pollutants in the established electrocatalytic system would also be investigated, and the kinetics as well as reaction mechanism would be studied. Finally, the mechanism and methods on improving performance of the electrocatalytic oxidation system would be discussed based on the electrode materials characteristics and electrochemical analysis. This study would add some important information to the present knowledge in the field of electrocatalysis, promote the development of electrocatalytic technology in water and wastewater treatment, and provide ideas and theoretical basis for the exploitation of new efficient water and wastewater treatment system.

基于硫酸根自由基的高级氧化技术在水处理领域具有广阔的应用前景，然而以电化学水处理体系中广泛应用的支持电解质硫酸盐为原料，进行硫酸根自由基的循环再生，并用于催化氧化降解水中有机污染物的研究尚未见报道。构建原位再生硫酸根自由基的电催化氧化体系，力图在有机污染物降解反应体系中实现硫酸根离子向硫酸根自由基/过硫酸盐的原位生成与再生循环，以及过硫酸盐活化剂Fe2+的再生和重复利用，具有很好的研究价值和应用潜力。本项目将在制备和优选电极材料的基础上，实现基于硫酸根自由基的间接电催化过程；考察硫酸根自由基的生成规律与该体系催化氧化降解有机污染物的效能并分析影响因素，推导动力学并探讨反应机理；结合电极材料表征和电化学分析结果，探讨强化该体系催化氧化效能的机制与方法。该研究将丰富电催化水处理理论和促进电催化水处理技术发展，并为开发新型高效的水处理系统提供思路与依据。

电化学水处理技术和过硫酸盐高级氧化技术在水处理领域都具有广阔的应用前景，本项目建立了电化学水处理技术与过硫酸盐高级氧化技术的耦合体系，选取合适的电极材料，合理设计反应器，构建适合过硫酸盐和硫酸根自由基、羟基自由基生成、以及提高氧化剂和活化剂利用效率的电化学体系，分析不同类型有机物在该体系中的降解去除规律，推导动力学和反应机理，探讨和分析强化该耦合体系去除水中有机污染物效能的机制与方法。研究结果指出，在较低的初始硫酸根离子浓度和温和的初始电解条件下，充分利用阴阳极功能，直接利用溶液中的硫酸根离子在电化学体系中合成过硫酸盐，并选择合适的活化方式，将其用于有机污染物去除是可行的；过硫酸盐活化剂在不同的阴极体系中循环再生重复利用也是可行的；不同结构和不同分子量大小的目标有机物在所构建的反应体系中可发生不同程度的降解，在目标有机物的降解反应过程中均检测到了羟基自由基和硫酸根自由基的存在，但不同的反应体系中对目标有机物降解起主导作用的自由基类型有所区别；电极材料是否参与反应过程导致不同体系的反应机理有所不同，对于反应体系的性能有明显影响；所构建的电化学-过硫酸盐耦合体系可以用于实际的难降解污水处理，实际污水中的复杂组份一方面使得污水处理难度增加，另一方面也为处理过程提供了一些可利用的资源（如：氧化剂、活化剂、支持电解质等）。本项目的研究结果为电化学与过硫酸盐活化相关的水处理研究提供基础数据和理论依据，为实际难降解污水的处理提供参考，也为开发新型高效污水处理系统提供新的思路。