Peracetic acid-driven advanced oxidation processes for wastewater treatment: Demystifying organic radicals and non-radical species
Guanglei Yao, Xuefei Zhou, Haiping Gao, Tongcai Liu, Yalei Zhang, Jiabin Chen
Abstract
Peracetic acid (PAA) based advanced oxidation processes (AOPs) have received increasing attention in wastewater treatment. However, it is challenging to identify the radical and/or non-radical species and elucidate the intrinsic interaction mechanisms involved in PAA-based AOPs. This work presents a systematic review of the selective generation mechanisms of radicals (hydroxyl and organic radicals), with a focus on organic radicals, and non-radical species (reactive complexes (RC), high-valent metals (HVM), singlet oxygen (1O2), and electron transfer process (ETP)). Furthermore, we examine various strategies for the precise identification and characterization of radical and/or non-radical species (e.g., quenching, chemical probes, spectroscopy, mass spectrometry, and electrochemical testing), and emphasize existing controversies. Subsequently, we provide an in-depth discussion of the reaction mechanisms between the reactive species and the contaminants/water matrices, as well as the potential for generating halogenated byproducts. Finally, we highlight the challenges and opportunities of the PAA-based AOPs in wastewater treatment, aiming to inspire future research endeavors that promote the practical application of PAA-based AOPs in wastewater treatment.