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

Ultraviolet light-induced homolysis of hydrogen peroxide (UV/HO) can generate powerful hydroxyl radicals (OH) for sustainable water purification. However, the efficiency of the conventional bulk-phase UV/HO 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/HO 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 HO. 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/HO water treatment systems.