Modeling the Kinetics of UV/Peracetic Acid Advanced Oxidation Process.

Peracetic acid combined with UV (i.e., UV/PAA) has emerged as a novel advanced oxidation process (AOP) for water disinfection and micropollutant degradation, but kinetic modeling for this AOP was lacking. In this study, a comprehensive model was developed to elucidate the reaction mechanisms and simulate reaction kinetics of UV/PAA process. By combining radical scavenging experiments and kinetic modeling, accurate quantum yield of PAA under UV (Φ = 0.88 ± 0.04 mol-Einstein) was determined via simultaneously quenching OH and CHC(O)O with 2,4-hexadiene. The comparison between experimental observations and model predictions over a wide range of conditions allowed estimation of the rate constants of PAA with OH ( = 1.3 ± 0.2 × 10 M s) and HO ( ≤ 5 × 10 M s) with good accuracy. With derived Φ, and , the kinetic model accurately predicts PAA decay under UV photolysis across varying PAA and HO concentrations and water pH (5.8-7.2). Meanwhile, the model reveals that UV/PAA generates a lower OH concentration than UV/HO at equivalent oxidant concentrations, with CHC(O)OO as the most abundant carbon-centered radical. This study significantly improves the knowledge of reactive species generation and reaction kinetics and mechanisms under UV/PAA, and provides a useful kinetic model for this AOP in water treatment.