A Novel UVA/ClO 2 Advanced Oxidation Process for the Degradation of Micropollutants in Water

• Published in: Environmental science & technology 2022-01, Vol.56 (2), p.1257-1266
• Main Authors: Peng, Jiadong, Yin, Ran, Yang, Xin, Shang, Chii
• Format: Article
• Language: English
• Subjects: Chlorine; Disinfection; Oxidation-Reduction; Photolysis; Ultraviolet Rays; Water; Water Pollutants, Chemical - analysis; Water Purification
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.1c05133

Ultraviolet (UV)-based advanced oxidation processes (AOPs) are increasingly used for the degradation of micropollutants in water and wastewater. This study reports a novel UVA/chlorine dioxide (ClO ) AOP based on the photolysis of ClO using energy-efficient UV radiation sources in the UVA range (e.g., UVA-LEDs). At a ClO dosage of 74 μM (5.0 mg L as ClO ) and a UV fluence at 47.5 mJ cm , the UVA /ClO AOP generated a spectrum of reactive species, including chlorine oxide radicals (ClO ), chlorine atoms (Cl ), hydroxyl radicals (HO ), and ozone at a concentration of ∼10 , ∼10 , ∼10 , and ∼10 M, respectively. A kinetic model to simulate the reactive species generation in the UVA /ClO AOP was established, validated against the experimental results, and used to predict the pseudo-first-order rate constants and relative contributions of different reactive species to the degradation of 19 micropollutants in the UVA /ClO AOP. Compared to the well-documented UVC /chlorine AOP, the UVA /ClO AOP produced similar levels of reactive species at similar oxidant dosages but was much less pH-dependent and required much lower energy input, with much lower formation of chloro-organic byproducts and marginal formation of chlorite and chlorate.