On the mechanism and selectivity of a novel iodine/peracetic acid process for the efficient and rapid elimination of micropollutants

Abstract

In recent years, halogen radical-based advanced oxidation processes (AOPs) have shown promise for metal-free, highly selective elimination of phenolic pollutants with high mineralization. This study explored a novel approach combing peracetic acid (PAA) and naturally available I− to efficiently remove bisphenol A (BPA) over a broad pH range (2–8). A dose of 500 μM PAA and 100 μM I− at a pH of 3 completely eliminated 43.8 µM of BPA within 10 min. Aside from I−, two more halogen ions, Cl− and Br−, could also enhance BPA elimination in the presence of PAA. Based on quenching experiments and density functional theory (DFT) thermodynamic calculations, only I− among the three halogen ions can react with PAA (primarily through the single electron transfer pathway) to generate •I, which efficiently removes BPA. The Cl− and Br− only contribute partially to the BPA removal, mainly through HOCl and HOBr following the oxygen atom transfer pathway. The water matrices had no noticeable influence on the I−/PAA process, and eliminating micropollutants with electron-rich groups from actual water samples remained effective. This work proposes an innovative and feasible technique for PAA-based AOPs and showcases its promising applicability for the treatment of phenolic contaminants in wastewater.