Abatement of Structurally Diverse Micropollutants by the UV/Permanganate Process: Roles of Hydroxyl Radicals and Reactive Manganese Species
Kaiheng Guo, Wenrui Wei, Sining Wu, Weihua Song, Jingyun Fang
Abstract
The UV/permanganate process was recently reported to be an innovative advanced oxidation process (AOP) that generates HO• and reactive manganese species (RMnS) of Mn(V). This study further identified that Mn(V) is first generated by UV/permanganate, followed by its transformation into Mn(III) and the final production of MnO2. The UV/permanganate process was effective for the degradation of 26 structurally diverse micropollutants, with kobs′ ranging from 0.05 to 1.8 min–1. HO• was active in the degradation of all micropollutants, while Mn(V) was selective toward aromatics containing carboxylic groups. The roles of Mn(III) and MnO2 formed in situ were not important for the degradation of micropollutants under neutral conditions; however, under acidic conditions, in situ-formed MnO2 was attributable to the abatement of phenolics, anilines, and propranolol as a catalyst of permanganate. HO• was scavenged by water matrix components, such as (bi)carbonate, bromide, and natural organic matter (NOM) while simultaneously forming CO3•–, Br•/Br2•–, and Mn(III)–NOM complexes that promoted micropollutant degradation. The electrical energy per order (EE/O) for 90% micropollutant transformation by UV/permanganate was comparable with that by UV/H2O2 in simulated drinking water. This study comprehensively elucidates the roles of HO• and diverse RMnS in micropollutant degradation by UV/permanganate under practical conditions.