碳-金属复合催化剂诱生吸附态自由基高效降解焦化废水中酚类污染物的机理研究

Aiming at the efficient degradation of typical phenolic pollutants (PPs) in coking wastewater, this project focuses on the design and preparation of series of novel ZIF-8-derived nitrogen-doped porous carbon-metal (cobalt/manganese/iron and their oxide/sulfide/phosphide) composite catalysts. The contrast researches concerning the dynamic/thermodynamic degradation behaviors of PPs (phenol/cresol/chlorophenol/nitrophenol) by the adsorbed radicals from persulfate/peroxymonosulfate activation, and their changes with environmental factors will be conducted. The structure-activity relationship between the molecular characteristics of PPs, physical/chemical structures of the catalyst and pollutant degradation performance will be established. Using the structure characterization, mathematical model and theory calculation methods, the key adsorption and catalytic sites will be identified. The generation mechanism of adsorbed radical and the in-situ transformation micromechanism of pollutants will be discovered. The evaluation of technical adaptability will be conducted in the actual wastewater. This project will provide theoretical guidance for the design of novel heterogeneous catalyst with high site density, high adsorption performance and high conductivity, as well as the development of new technology for efficient degradation of PPs in complex environment.

针对焦化废水中典型酚类污染物（PPs）高效降解难题，拟自主设计与优化制备系列新型ZIF-8衍生氮掺杂多孔碳-金属（钴/锰/铁等单质及其氧/硫/磷化物）复合催化剂，对比研究其活化过硫酸盐诱生吸附态自由基降解PPs（苯酚/甲酚/氯酚/硝基酚等）的动力学、热力学等行为，并结合关键环境因子的影响规律，建立PPs分子特性、催化剂理化结构与PPs降解性能之间的构效关系，借助结构表征、数理模型、理论计算等手段识别关键吸附和催化位点，揭示吸附态自由基诱生机理和PPs原位转化微观机制，并于实际废水中开展技术适应性评价，为兼具高位点密度、高吸附性、高导电性特征的新型非均相催化剂设计、复杂环境中PPs的高效降解新技术开发提供理论指导。

基于过一硫酸盐的高级氧化技术（PMS-AOP）因适用pH范围广、无铁泥产生等优势，有望替代传统芬顿工艺应用于焦化废水处理，但仍具有催化效率低、易受高浓度无机盐和低温等不利条件影响等缺陷。项目以提高PMS-AOP催化效率与抗干扰性为目标，制备了包括yolk-shell型碳多面体包覆磷化钴、中空石墨碳基单原子钴、二维氮化碳基单原子铁等“三高”型（高位点密度、高吸附性、高导电性）碳-金属复合催化剂，通过系统表征材料在制备各阶段的理化结构演变，阐明了催化剂的生长机制和结构优化调控方法。全面考察了催化剂结构参数和环境因子对污染物吸附和降解动力学与热力学行为的影响，所得最优化催化剂在同等条件下的反应速率常数较已报道非均相催化剂高1~2个数量级，且在高盐（浓度达100 mmol L-1）和低温（2 oC）环境中仍表现出优异的反应活性；进一步借助数理模型和理论计算，深入揭示了纳米限域效应加快反应速率、表面微电场增强催化耐盐性、表面接触氧化提升抗低温性等微观机制。此外，设计搭建了固定床、流化床柱反应器，实现了长时间动态水处理（最长超12天）和目标污染物零排放。研究为高效碳-金属复合催化剂的设计合成提供了科学参考，有望推动PMS-AOP在高盐、低温等极端环境中的应用。