Modeling the Kinetics of UV/Peracetic Acid Advanced Oxidation Process

摘要

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_(254) (Φ = 0.88 ± 0.04 mol-Einstein~(-1)) was determined via simultaneously quenching ~·OH and CH_3C(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 (k·_(OH/PAA) = 1.3 ± 0.2 × 10~9 M~(-1) s~(-1)) and HO_2~· (k_(HO_2~·/PAA) ≤ 5 × 10~2 M~(-1) s~(-1)) with good accuracy. With derived Φ, k·_(OH/PAA) and k_(HO_2~·/PAA), the kinetic model accurately predicts PAA decay under UV_(254) photolysis across varying PAA and H_2O_2 concentrations and water pH (5.8-7.2). Meanwhile, the model reveals that UV/PAA generates a lower ~·OH concentration than UV/H_2O_2 at equivalent oxidant concentrations, with CH_3C(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.