Accelerated Pollutant Degradation by UV/H₂O₂ at the Air–Water Interface of Microdroplets

Abstract

Ultraviolet light-induced homolysis of hydrogen peroxide (UV/H 2 O 2 ) can generate powerful hydroxyl radicals ( • OH) for sustainable water purification. However, the efficiency of the conventional bulk-phase UV/H 2 O 2 system is limited by the low yield and utilization of • OH, in turn necessitating high UV energy input and long purification period. In this study, we present an innovative UV/H 2 O 2 microdroplet system for enhanced pollutant degradation. The degradation of pollutants in sprayed microdroplets was accelerated by 8.5–63.3-fold compared to those in bulk water, demonstrating universal effectiveness across a range of pollutant types and diverse aqueous matrices. This enhancement stems from elevated • OH production at the air–water interface due to the enhanced UV absorbance of H 2 O 2 . The production of • OH in the microdroplet system was 45-fold higher than that in bulk water, facilitating rapid • OH-mediated pollutant degradation. Moreover, pollutants accumulate at the air–water interface, where • OH is concentrated, leading to higher utilization of • OH for mediating pollutant degradation before quenching. Our findings provide a solution to overcome the bottlenecks in • OH production and utilization, offering insights for improving the efficiency of UV/H 2 O 2 water treatment systems.