吸电子基团改性锌铁氧体制备及其催化臭氧降解典型PPCPs机理研究

Some typical pharmaceuticals and personal care products (PPCPs) have ozone-resistant property, being the difficulty of relevant wastewater treatment technologies. In this project, zinc ferrite will be tuned by the charge induced effect of electron withdrawing group, for the purpose of elevating its catalytic activity in achieving effective ozonation of those contaminants. Zinc ferrite will be modified by SO42ˉ (O=S=O) or fluorine, based on which the key controlling factors for catalytic sites will be identified. On this basis, efficient degradation of PPCPs by catalytic ozonation system will be established. The degradation of contaminants in different reaction conditions will be evaluated. The ozone decomposition and radical generation during the course of catalytic ozonation will be kinetically explored. By conducting X-ray absorption fine structure spectroscopy (XAFS) and attenuated total reflection FTIR (ATR-FTIR) analysis, the mechanism responsible for ozone decomposition and radical generation within solid-liquid interface will be investigated. In addition, charge state and energy structure of zinc ferrite changed by electron withdrawing group will be analyzed using quantum chemical calculation. Based on these progresses, the enhanced mechanism of surface Lewis acid site by electron withdrawing effect will be proposed. Moreover, the effect of energy structure on interface reactivity will be elucidated. This project may provide theoretical support in catalyzing ozonation of typical PPCPs from the aspect of optimizing electronic structure of metal oxide.

针对部分药品及个人护理用品（PPCPs）难被臭氧氧化的难点，本项目拟利用吸电子基团对锌铁氧体的电荷诱导效应，提高其臭氧催化活性进而实现典型PPCPs的有效降解。通过制备硫酸根或氟改性锌铁氧体，识别其臭氧催化位点的关键控制因子；构建基于PPCPs降解的催化臭氧反应体系，阐明不同反应条件下污染物降解规律，建立臭氧分解和自由基生成动力学方程，利用X射线吸收精细结构谱（XAFS）和衰减全反射傅里叶变换红外光谱（ATR-FTIR）揭示固-液界面臭氧分解及自由基生成机制；通过量化计算手段分析吸电子基团对锌铁氧体电荷状态和能级结构的调控规律，揭示吸电子效应对锌铁氧体表面Lewis酸位点的强化机制，阐明能级结构对界面反应途径的调控规律。从优化金属氧化物电子结构角度，为催化臭氧技术降解典型PPCPs提供理论依据。

非均相臭氧催化氧化技术处理废水的关键是高效分解溶解态臭氧，生成羟基自由基（•OH）和其他含氧自由基物种。在实际废水处理过程中，非均相臭氧催化氧化技术受限于催化剂表面活性位点的钝化和废水中无机阴离子对•OH的淬灭。鉴于零价硼（ZVB）和臭氧分子可通过原子轨道匹配效应形成强表面化学吸附作用，本研究采用零价硼催化臭氧（ZVB/O3）降解废水中的有机污染物，验证了ZVB对臭氧的高分解效率，探究了无机阴离子对ZVB/O3体系氧化性的影响机制，阐明了原子轨道匹配效应对臭氧分解的促进机制。另外，臭氧催化氧化体系中的初始氧化剂是臭氧，通过界面调控促进其分解产生瞬态强氧化剂是研究热点。对于臭氧催化氧化体系，强化催化剂表面活性位点是提高催化臭氧效率的关键问题。为此，识别初始氧化剂的分解控制因素和理论验证影响污染物降解的关键问题十分必要。.首先，考察了ZVB/O3降解有机污染物的效能和污染物降解机理。结果表明，在臭氧浓度35.8 μM、ZVB浓度200 mg Lˉ1、初始pH=5.6、阿特拉津（ATZ）浓度6.0 μM条件下，60 s内可降解97.4%的ATZ，且污染物降解的归一化动力学系数远超过大部分文献报道的数据。ZVB的高臭氧催化活性部分归因于ZVB表面的B2O3钝化层可自发溶解于水中，避免ZVB表面活性位点的钝化。采用热聚合法制备了氮化碳（CN）、掺杂氧氮化碳（CNO），HNO3高温回流CN和CNO制备了羧基功能化氮化碳（CN-10）、羧基功能化掺杂氧氮化碳（CNO-10），考察了其催化臭氧降解对氯苯甲酸（p-CBA）和阿特拉津效能和机理。由于CNO-10比CN-10具有更低的生成能，CN骨架预掺杂氧原子产生的缺陷可在HNO3氧化过程引入更多羧基。密度泛函理论和室温EPR研究了碳基质材料因大量接枝羧基引起的电子结构的变化。相比CN-10，CNO-10催化臭氧降解p-CBA和相应Rct值分别提高1.12和1.48倍，远优于非催化臭氧。