Degradation of organic pollutants by peroxymonosulfate activated by MnO2 with different crystalline structures: Catalytic performances and mechanisms

By Zhi-Gang Zhou, Hong-Mei Du, Z. Dai, Yi Mu, L. Tong, Q. Xing, Shanfang Liu, Z. Ao, J. Zou. Chemical Engineering Journal, 2019

191 citations recorded by the source corpus.

Abstract 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 (SO4 −) and hydroxyl radicals ( OH) 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 MnO2 with different morphologies.

Subfields: Biomedical Engineering, Renewable Energy, Sustainability and the Environment, Water Science and Technology

View Paper: https://www.semanticscholar.org/paper/c79b3bda19488e00f9ef4509b4b579120ff049d2