Reactive complexes mediated singlet oxygen production by MnO2 catalyzed peracetic acid: Characterization and DFT study

Abstract

Advanced oxidation technology based on peracetic acid (PAA) has been a hot issue in the remediation of refractory organic pollutants. Here, we investigated manganese dioxide (α-MnO2) effectively activate the in-situ generated PAA by rapid perhydrolysis of sodium percarbonate (SPC) and tetraacetylethylenediamine (TAED) to degrade sulfamethoxazole (SMX). This system followed non-radical pathway only dominated by singlet oxygen (1O2), which can exhibit excellent anti-interference capacity. The generation of metastable manganese intermediates (Mn-PAA*) is a key step in the formation of 1O2. The formation of Mn-PAA* is confirmed by electrochemical and in-situ Raman tests. With the help of density functional theory (DFT), we have probed the behavior of PAA activation on different crystal planes to produce 1O2, with OH cleavage to generate MnIV−O-OOCCH3 being the decisive step for the formation of 1O2. This study is the first to investigate the mechanism of non-radical mediated PAA activation by α-MnO2 and in-depth research the role of Mn-PAA* in the 1O2 generation. The proposed new insights into non-radical process of PAA activation by transition metal will further advance the application of PAA-based AOPs.