氧空位促进异质结光催化剂去除全氟辛酸的机制研究

Perfluorooctanoic acid (PFOA), a represented persistent organic pollutant, has been regarded as a emerging micropollutant because of its low concentration, high toxicity and degradation-resistant. It can be hardly removed by the traditional water treatment technology, resulting in a large amount of residue and accumulation of PFOA in the environment, and it is a potential threat to the health of humans and animals. In this work, we will focus on the study of oxygen vacancy promoting photocatalytic degradation of PFOA by hybird photocatalysis system. And the goal of this work is to design an high-efficiency photocatalytsis system for PFOA removing. A novel heterojunction system with oxygen vacancy will be prepared; the synthesis parameters of the method will be optimized; the intermediate products of the photocatalytic degradation of PFOA will be identified; next, the pathway of photocatalytic PFOA degradation over the heterojunction composite and the corresponding mechanism will be studied. Finally, the mechanism of oxygen vacancy in activation of surface adsorption of PFOA and regulation of the charge carrier transfer and separation with large amount of active radicals production will be proposed. The structure-activity relationship of oxygen vacancy will be established. The results of our work will provide technical support for the deep treatment of wastewater containing PFOA, and enrich the basic understanding of photocatalytic removal of refractory pollutants.

以全氟辛酸PFOA为代表的难降解污染物具有浓度低、毒性大、难降解的特点。目前的传统水处理工艺无法将其完全去除，导致其在环境中大量残留与累积，对人类及其它生物危害极大。本项目以高效去除水中难降解污染物全氟辛酸为目标，围绕氧空位强化光催化体系去除PFOA性能开展工作。重点研制基于氧空位的新型异质结复合光催化体系，首先优化复合体系的制备参数，明晰异质结结合方式；其次，研究反应条件对光催化降解PFOA的影响，并结合中间产物定性与定量分析结果，揭示光催化催化降解PFOA的反应路径与作用机制；最后，解析氧空位在强化表面活化PFOA及调控体系活性自由基产生种类及数量的作用机理，阐明氧空位对异质结结构与性能之间的构效关系。本项目研究可为深度处理PFOA废水提供技术支持，丰富对光催化去除难降解污染物的认识。

作为新兴微污染物，以全氟辛酸（PFOA）等为代表的难降解污染物具有浓度低、毒性大、难降解的特点。目前的传统水处理工艺无法将其完全去除，导致其在环境中大量残留与累积，对人类及其它生物危害极大。本项目通过构建多种新型的复合光催化剂材料，并结合其他高级氧化技术，对其光催化降解有机污染物的能力进行研究。首先制备了二维层状异质结复合催化剂Bi12O17Cl2/g-C3N4，该复合催化剂具备优异的光催化活性，该复合催化剂光生载流子传递方式为传统的type-II型，这有利于异质结界面处的光生载流子分离；进一步制备了基于Z机制的二维层状PI/BiOIO3光催化剂，该催化剂对PFOA及双酚A均表现出较好的催化活性。XPS和光电表征结果表明该异质结中氧空位的存在促进了光生载流子的分离，使复合催化剂具有较优的光生载流子迁移与分离能力，同时自由基猝灭实验等结果表明该复合催化剂中光生载流子按照Z机制方式进行传递，在提高光生载流子分离能力的同时，保留了催化体系的氧化还原能力。进一步，为提高光催化体系的活性，将光催化与芬顿或过硫酸盐氧化技术相结合，分别研究了基于光催化活化O2产双氧水的杂多酸（PW9）共价修饰的TiO2复合光催化剂体系和基于光电化学活化过硫酸盐的新型BiVO4光阳极-MnFe2O4@CFP光阴极的光电体系。所制备复合催化体系均具有较优的光催化去除污染物的能力。本研究有利于推进新型光催化体系的构建，为光催化技术的应用提供一定的理论基础。