活化过硫酸盐的双活性位碳基催化剂及其非自由基反应降解酚类污染物的机理研究

Persulfate activation by carbonaceous materials is a promising pollution control technology in removal of refractory organic pollutants. Yet, it is a big challenge to fabricate a highly efficient and stable non-radical reaction system. In this project, we will assembly carbonaceous catalysts with both electron-rich and electron-deficiency active sites by employing carbonization of nitrogen containing polymers, molecular design of polymers and covalent modification of carbonaceous materials. Phenolic pollutants like 4-chlorophenol will be used as the model pollutants, and the methods such as additives of scavengers will be employed to differentiate the radical or non-radical reaction pathways and estimate their contributions. By comparing the mechanism and reaction kinetics with those non-radical reactions including singlet oxygen, enzyme-like oxidation, and multi-electron oxygen reduction reactions, and employing methods including in-situ characterizations and electrochemistry, we will investigate the affinity between catalysts and organic substrate or persulfate, and the mechanism on electron transfer, and reveal the controllable effects of active sites on the reaction efficiency of various substrates. Combining the results from theoretical calculation and quantitative structure-activity relationship, we will elucidate the coupling effects of different active sites and degradation law of phenolic pollutants. According to the influence rules of reaction conditions in the continuous degradation of phenolic pollutants, we will explore approaches to enhance the affinity toward substrates and stability of catalysts, and build up an effective new technology featured by non-radical reactions for phenolic pollutants containing wastewater treatment. The research results will promote the development of pollution control technology based on non-radical reactions, and enlighten the precise design of carbonaceous materials.

碳基材料活化过硫酸盐是具有重要前景的难降解有机污染控制技术，构建高效稳定的非自由基反应体系是个难题。本项目拟借助碳化含氮聚合物的方法、通过聚合物的分子设计和碳材料的共价修饰，组装制备含富电子和缺电子双活性位的碳基催化剂；以4-氯酚等酚类污染物为研究对象，采用自由基捕获等实验辨析活化过硫酸盐的自由基和非自由基反应及其贡献；通过与单线态氧、类酶催化、多电子氧还原等非自由基反应原理和动力学的比对分析，运用原位红外和电化学手段，研究催化剂与底物间的亲和作用和电子转移机理，揭示不同活性位对反应效率的影响规律；结合理论计算和定量构效关系研究，阐明双活性位的耦合增效机制和酚类污染物的降解规律；通过研究动态实验条件对去除效率的影响，探索底物亲和性和催化剂稳定性的强化途径；提出以非自由基反应为特征、高效稳定处理难降解含酚废水的新技术。研究成果将推动非自由基污染控制技术的发展，并启迪碳材料精准设计的新思路

非自由基反应的过硫酸盐高级氧化技术在难降解有机污染控制方面具有广泛应用前景，而构建高效稳定的活化过硫酸盐催化剂是当前面临的挑战。本项目围绕研究计划中“活化过硫酸盐的活性位及构效关系”以及“非自由基反应降解酚类污染物的定量构效关系”两个关键问题开展系统研究，研制了四类高活性的催化剂，并提出相应合成方法，包括：高氮含量的氮掺杂碳及其多巴胺包裹-限域热解合成方法；过渡金属和氮活性位耦合的M-N-CNTs单原子催化剂及其联吡啶螯合热解合成方法；MnN5-C3N4高配位单原子催化剂及其氯化铵介导热解合成法；CuO纳米片及其共沉淀合成方法。同时，在增强活化反应效率的活性位相关机理机制方面，（1）揭示了总氮含量以及吡啶氮和吡咯氮总量相关的过硫酸盐活化规律；（2）阐明了自旋态所决定的金属活化过硫酸盐性能；（3）发现了高配位的MnN5活化过一硫酸盐形成高活性四价锰中间态的作用机制；（4）提出了Cu(III)介导的高效利用PMS降解酚类污染物的作用机制；（5）揭示了碘空位活化PMS的非自由基作用机制。另外，在有机污染物降解规律方面，构建了L-H 二元动力学模型描述反应的表面亲和作用和电子转移；建立了定量预测反应动力学常数的多参数线性自由能相关模型和QSAR模型；并提出单电子转移主导的活化反应规律。上述研究全面阐释活化过硫酸盐的非自由基反应机理，并探明催化剂具有高效活化过硫酸盐性能的若干结构特征，为研制过硫酸盐高级氧化技术的功能材料和应用技术提供理论指导和技术参考。本项目共发表标注基金资助的SCI论文18篇，包括3篇Environ Sci & Technol等；获授权国家发明专利2项；出席国际国内会议9次；培养硕士研究生5名，博士后1名。