Degradation of organic pollutants by peroxymonosulfate activated by MnO2 with different crystalline structures: Catalytic performances and mechanisms
Degradation of organic pollutants by peroxymonosulfate activated by MnO2 with different crystalline structures: Catalytic performances and mechanisms
复制标题
不同晶型MnO2活化过一硫酸盐降解有机污染物的催化性能与机理
DOI：
10.1016/j.cej.2019.05.170
复制
发表时间：
2019
影响因子：
15.1
通讯作者：
Zou Jian Ping
中科院分区：
文献类型：
--
作者：
Zhou Zhi Gang;Du Hong Mei;Dai Zhenhua;Mu Yi;Tong Lin Lin;Xing Qiu Ju;Liu Shan Shan;Ao Zhimin;Zou Jian Ping
本研究以α-MnO_2(OL-1)为原料，在水热条件下，通过形态和相变的方法合成了具有长而均匀纳米纤维的δ-MnO_2(OMS-2)材料。系统考察了OMS-2和OL-1对活化过一硫酸盐降解水中4-硝基苯酚的催化性能。根据Brunauer Emmett Teller(BET)、热重分析仪(TGA)、H2程序升温还原(H2-TPR)、循环伏安、X射线光电子能谱(XPS)和密度泛函理论(DFT)的计算结果，OMS-2比OL-1具有更大的BET面积、更多的活性中心、更好的吸附能力、更快的电子转移速率和更多的Mn的多种价态。这些结果也很好地说明了OMS-2比OL-1具有更好的催化性能。电子顺磁共振和自由基定量实验结果表明，硫酸盐自由基(SO4·点−)和羟基自由基(点·OH)是主要的氧化剂，OMS-2比OL-1具有更强的自由基产生能力。LC-MS结果表明，4-NP在OMS-2/PMS体系中有两条降解途径，其降解机理与OL-1/PMS体系相似。最后，基于两种不同形貌的MnO2，提出了PMS的活化机理、自由基的形成机理以及4-NP的降解机理。
In this study, a novel α-MnO2(OMS-2) material with long and uniform nanofibers was synthesized by morphological and phase transitions from δ-MnO2(OL-1) under a hydrothermal reaction. We systematically investigated the catalytic performances of OMS-2 and OL-1 for the activation of PMS (peroxymonosulfate) to degrade 4-nitrophenol (4-NP) in water. According to the results from Brunauer Emmett Teller (BET), thermo gravimetric analyzer (TGA), H2-temperature programmed reduction (H2-TPR), cyclic voltammetry, X-ray photoelectron spectroscopy (XPS), and density-functional theory (DFT) calculation, OMS-2 has a larger BET area, more active sites, better adsorption ability, a faster electron transfer rate, and more multiple valence states of Mn than OL-1. These results also well illustrate OMS-2 has much better catalytic performance than OL-1. The results of the electron paramagnetic resonance (EPR) and the radical quantification experiments confirmed that sulfate radicals (SO4radical dot−) and hydroxyl radicals (radical dotOH) were the main oxidants and OMS-2 has better radical generation capability than OL-1. The LC-MS results indicated that there were two routes for the degradation of 4-NP and the degradation mechanism of 4-NP in the OMS-2/PMS system was similar to that in the OL-1/PMS system. Finally, we proposed the PMS activation mechanism, the formation mechanism of radicals, and the degradation mechanism of 4-NP based on the two different kinds of MnO2with different morphologies.