水钠锰矿改性及其多相类芬顿降解有毒有机污染物性能调控

Birnessite has very high heterogeneous Fenton-like reactivity for the organic pollutant treatment. However, undesired disproportion decomposition of H2O2 into O2 has significant competitive advantage at the surface of birnessite, which greatly increases the H2O2 loss, and prevents the birnessite-based Fenton-like reaction from the practical applications. So far, how to effectively depress the disproportion decomposition of H2O2 to promote the transform efficiency of H2O2 into reactive oxygen species (ROS) during the Fenton-like process, has not yet been systematically studied. .In this project, several suitable metal ions would be used to modify the Mn-vacancies in the [MnO6] layers of birnessite to form TCS species via surface complexation, which would regulate several key steps of the Fenton-like reaction, such as the adsorption, reaction, and the desorption process at the surface of birnessite. Therefore, the over-oxidation of H2O2 into O2 can be depressed, and the transform efficiency of H2O2 into ROS can be greatly improved. Specifically, the detailed catalyzed transform mechanism of adsorbed H2O2 at the surface of birnessite, the effect of the surface modification to the adsorption and the surface reaction behaviors of special organic pollutant, and the chemical stability and anti-passivation performance of modified birnessite, will be systematically studied. Finally, a much favorable birnessite-based Fenton-like reaction system would be proposed for the treatment of organic pollutant in water, which has either high Fenton-like reactivity or high H2O2 efficiency.

水钠锰矿材料具有很高的多相类芬顿活性。然而，H2O2在水钠锰矿表面歧化分解生成O2作为优势竞争反应，极大地增加了H2O2的损耗，影响了锰基多相类芬顿反应的有效应用。如何有效抑制类芬顿反应中的H2O2歧化分解，促进H2O2向活性氧物种（ROS）的有效转化，迄今尚未得到系统的研究。本项目拟选用合适的金属离子对水钠锰矿[MnO6]层的锰空位进行表面络合改性，形成TCS物种，对水钠锰矿表面的吸附、反应过程和脱附等影响类芬顿反应过程的重要步骤进行调控，抑制H2O2向O2的转化，极大地提高H2O2转化为ROS的效率。具体地，拟对H2O2在改性水钠锰矿表面的催化转化机理、改性对于目标有机污染物的吸附和表面反应行为的影响以及改性材料的化学稳定性和抗钝化性能，开展系统的研究，以构建一个可用于水体有机污染物高效处理的，既保留锰氧化物高的类芬顿活性、又具有高的H2O2利用效率的锰基类芬顿催化反应体系。

水钠锰矿等变价过渡金属氧化物材料具有高的多相类芬顿活性，水钠锰矿材料中锰离子的氧化还原循环及其与H2O2、PMS等含过氧键氧化剂之间的氧化还原反应，可以在不同的条件下生成ROS或高价金属活性中心，用于有机污染物的快速氧化降解。然而，过氧键在水钠锰矿表面存在多种反应途径，如H2O2在水钠锰矿表面易歧化分解生成O2，极大地增加了H2O2的损耗，影响了锰基多相类芬顿反应的有效应用。本项目针对类芬顿催化剂的表界面设计，通过改善类芬顿催化剂的表界面电子转移、不同过渡金属离子氧化还原循环间的协同以及调控H2O2、PMS等分子中过氧键的裂解（均裂或异裂），以获得具有高的氧化剂利用效率的类芬顿催化反应体系。.研究表明，Cu2+离子通过占据锰空位，在水钠锰矿表面形成的三角共享的内层复合物（TCS物种），可以有效地抑制H2O2在水钠锰矿表面的过度络合，进而避免因大量超氧自由基生成引发的自损耗。表面的TCS物种展现了优秀的类芬顿反应活性，提高了H2O2的利用效率。Cu2+-TCS物种还对类芬顿反应中PMS活化机理起到了调制作用。与Bir/PMS体系的非自由基机理不同， Cu-Bir/PMS体系的类芬顿反应机理为自由基和非自由基共存机理，并且呈现了更高的有机物降解动力学。.类芬顿金属活性中心的化学状态改变对于其类芬顿性能具有直接的影响。考察了Fe掺杂的MoS2模拟典型的S配位Fe络合物类芬顿机理和性能后发现，H2O2加入后观察到了FeIV=O物种数量发生了快速且持续的累积，S配位的FeIV=O物种活性最佳。八体构型的1T相MoS2可以通过形成更好的类卟啉平面四配位结构加快Fe中心在类Fenton反应中生成FeIV=O的速率，显示更好的类Fenton催化活性。