Reagent-Free Degradation of Halogenated Disinfection Byproducts by UV-Microdroplets Via Dual Reactive Oxygen Species Synergistic Oxidation

Abstract

Halogenated disinfection byproducts (DBPs) pose a major safety concern for drinking water. Advanced oxidation processes (AOPs) for their removal are often limited by high energy consumption, secondary pollution, and potential toxic byproducts. This study presents a novel UV/microdroplets system, which achieves a 1.5-6-fold degradation enhancement for 22 halogenated DBPs in 30 minutes compared to conventional UV and UV/Ultrasound (US) treatments. After the treatment, the dehalogenation efficiencies of aromatic DBPs, aliphatic DBPs, and chlorite ions ranged from 31 to 81%, 19 to 90%, and 90%, respectively. For chloroform, degradation was over 6 times higher than the UV method, exceeding 50%. This enhancement arises from a synergistic mechanism: UV irradiation boosts burst generation of hydroxyl radicals (•OH, 75 μM) and singlet oxygen ( 1 O2, 7 μM) at the interface of microdroplets, mediating robust DBPs removal. Moreover, Hek-293 cell cytotoxicity assays showed a 4-21% reduction in cytotoxicity of these DBPs post-treatment. Practically, treating 80 mL of DBPs-containing water consumed 0.0175 kWh, and no external reagents were added. These findings demonstrate the UV/microdroplets system as a promising, feasible strategy for efficient and safe halogenated DBP remediation in drinking water treatment.