基于Fe-MOFs的催化剂构建及催化过硫酸盐降解有机物研究

Sulfate radicals-based advanced oxidation processes (SR-AOPs) are an emerging technologies to degrade the recalcitrant organic pollutants in aqueous solution. However, the existing catalytic decomposition reaction of persulfate is slow, which leaves efficient and rapid formation of sulfate radicals a research hotspot and difficulty. The modification of coordinatively unsaturated metal sites in Fe-based metal organic frameworks (Fe-MOFs) will improve the properties of catalysts, and the encapsulation of Fe3O4 nanoparticles in the open channels of Fe-MOFs which can induce a kind of confinement effect will make a further improvement. Meanwhile, the redox-active functional moiety as a redox mediator is grafted on the organic ligands in MOFs, which can accelerate the recycle of Fe(Ⅲ)/Fe(Ⅱ) on metal sites and Fe3O4. The adsorption property of MOFs will also be brought into full play. All those work is to design and synthesis efficient multifunctional catalysts which catalyze persulfate oxidation of organic compounds. In this research project, the influences on the catalytic performance of catalyst structure, composition and reaction conditions will be systematically investigated. The synergistic mechanism of all active sites, especially the mechanism of the redox mediator, will be revealed so as to identify the key factors affecting the catalytic performance. We will also establish kinetic model of free radicals formation and calculate free radicals formation rate in order to evaluate the catalytic property. In addition, we will identify the intermediates formed during the degradation of organic pollutants and propose the reliable degradation mechanism and pathway of organics. As a result, the mechanism of catalytic decomposition of persulfate and oxidation degradation of organics will be revealed. In a word, all of the results will provide theoretical support for SR-AOPs in the aspect of practical application on drinking water and sewage advanced treatment.

基于硫酸自由基（SO4•-）的高级氧化技术是处理水中生物难降解有机物的新技术，但现有的过硫酸盐催化分解反应较慢，如何高效快速形成SO4•-是研究的热点和难点。对铁基金属有机骨架材料（Fe-MOFs）的金属节点进行修饰以提高催化性能，在孔道中组装第二活性组分纳米Fe3O4，产生限域效应进一步提高催化性能；同时，在有机配体上嫁接氧化还原活性基团作为氧化还原介体，促进金属节点和Fe3O4中Fe(Ⅲ)/Fe(Ⅱ)循环，并发挥MOFs强大的吸附性能，构建具有催化、吸附和电子转移性能的高效多功能催化剂。研究催化剂结构、组成及反应条件对催化活性的影响；明晰氧化还原介体作用机理，识别影响催化性能的关键因素；建立自由基形成动力学模型，确定SO4•-形成速率，评价催化剂活性；考察有机物降解性能，解析中间产物，揭示催化过硫酸盐降解有机物机理。为该技术在饮用水及污水深度处理的实际应用提供理论支持。

铁基MILs系列材料已成为多相催化领域研究最为广泛的MOFs材料之一。本项目通过对Fe-MILs的金属节点、有机配体和孔道进行修饰，引入多种活性中心，构建具有协同效应的高效多功能催化剂。采用溶剂热法制备了一系列MIL(Fe)催化剂（如MIL-101、MIL-100、MIL-53和MIL-88B等）、核壳结构的Fe3O4@MIL-101(Fe)和CoxFe3-xO4@MOF-5复合催化剂，并将蒽醌-2-磺酸钠（AQS）、二茂铁（Fc）和间苯二酚等氧化还原介体嫁接到MOFs的配体上，成功制备了MIL-101(Fe)-AQS、MIL-101(Fe)-Fc和MIL-101(Fe)-Q催化剂，采用XRD、SEM、TEM、XPS和FTIR等手段进行表征；以双酚A、罗丹明B等作为研究对象，系统研究了Fe-MILs催化剂活化过硫酸盐的性能、有机物降解影响因素、有机物降解动力学、自由基的主要种类和形成动力学以及降解机理；此外，采用溶剂热法制备了BiOBr/MIL-88B(Fe)、磷钨酸@MIL-53(Fe)和AgCl@MIL(Fe)等复合光催化剂，研究了影响光催化性能的因素、主要活性物种和降解机理。上述研究结果对于污水的深度处理提供科学依据和技术支撑。本项目共发表SCI收录论文12篇，申请国家发明专利11项（已授权7项），提交会议论文6篇，培养硕士研究生7人（已毕业5人）。