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

Ultraviolet light-induced homolysis of hydrogen peroxide (UV/H2O2) can generate powerful hydroxyl radicals ((OH)-O-center dot) for sustainable water purification. However, the efficiency of the conventional bulk-phase UV/H2O2 system is limited by the low yield and utilization of (OH)-O-center dot, in turn necessitating high UV energy input and long purification period. In this study, we present an innovative UV/H2O2 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)-O-center dot production at the air-water interface due to the enhanced UV absorbance of H2O2. The production of (OH)-O-center dot in the microdroplet system was 45-fold higher than that in bulk water, facilitating rapid (OH)-O-center dot-mediated pollutant degradation. Moreover, pollutants accumulate at the air-water interface, where (OH)-O-center dot is concentrated, leading to higher utilization of (OH)-O-center dot for mediating pollutant degradation before quenching. Our findings provide a solution to overcome the bottlenecks in (OH)-O-center dot production and utilization, offering insights for improving the efficiency of UV/H2O2 water treatment systems.