Yoo Han Yi, Kim Min Sun, Shin Hyeyoung, Lim Jonghun
Department of Environment and Energy Engineering, Sungshin Women's University, Seoul 01133, Republic of Korea.
Graduate School of Energy Science and Technology (GEST), Chungnam National University, Daejeon 34148, Republic of Korea.
J Hazard Mater. 2022 Jul 5;433:128796. doi: 10.1016/j.jhazmat.2022.128796. Epub 2022 Mar 26.
Black TiO nanotube arrays (black TNAs) suffer from the low activity and deactivation for peroxymonosulfate (PMS) activation, which limit their application in the oxidative destruction of organic pollutants in water. Here, we report an efficient, environmentally benign, and cost-effective method to enhance the catalytic activity and prevent the deactivation of black TNAs in PMS activation by utilizing solar energy. Optical absorption and electrochemical analysis and density functional theory calculations demonstrated that abundant oxygen vacancies (estimated to be 26%) on the black TNAs surface markedly improved solar light absorption and electrical conductivity and played a critical role as a catalytic active site for PMS activation. As a result, the solar light-irradiated black TNAs/PMS system exhibited the higher phenol degradation rate (k = 0.0488 min) and total organic carbon (TOC) removal efficiency (~70%) compared to other TNAs systems. These results were ascribed to the switching of the reaction mechanism from non-radical mechanism to radical-involved. Black TNAs oxidized organic pollutants by mediating electron transfer from organics to PMS in the dark (i.e., a non-radical pathway). On the other hand, PMS activation under solar light irradiation involved the production of highly reactive sulfate and hydroxyl radicals (i.e., radical pathway), markedly improving the degradation and mineralization of organics. Additionally, the solar light-irradiated black TNAs showed relative pH-independence for PMS activation and durable catalytic performance without the loss of activity during the repetitive reaction cycles.
黑色二氧化钛纳米管阵列（黑色TNA）在过一硫酸盐（PMS）活化方面存在活性低和失活的问题，这限制了它们在水中有机污染物氧化降解中的应用。在此，我们报告了一种高效、环境友好且经济高效的方法，通过利用太阳能来提高黑色TNA在PMS活化中的催化活性并防止其失活。光吸收和电化学分析以及密度泛函理论计算表明，黑色TNA表面大量的氧空位（估计为26%）显著提高了太阳光吸收和电导率，并作为PMS活化的催化活性位点发挥了关键作用。结果，与其他TNA系统相比，太阳光照射的黑色TNA/PMS系统表现出更高的苯酚降解率（k = 0.0488 min）和总有机碳（TOC）去除效率（约70%）。这些结果归因于反应机制从非自由基机制转变为涉及自由基的机制。黑色TNA在黑暗中通过介导电子从有机物转移到PMS来氧化有机污染物（即非自由基途径）。另一方面，太阳光照射下的PMS活化涉及高活性硫酸根和羟基自由基的产生（即自由基途径），显著提高了有机物的降解和矿化。此外，太阳光照射的黑色TNA在PMS活化方面表现出相对的pH独立性和持久的催化性能，在重复反应循环中不会失去活性。
