Gas-liquid interfacial hydrogen bonds facilitate persistent peroxymonosulfate activation: Role of nanobubble-enabled...

Heterogeneous catalytic oxidation processes involving gas-liquid interfaces hold transformative potentials for water clean-up, yet their mechanisms remain insufficiently explored. Herein, we systematically elucidate the gas-liquid interfacial catalysis by leveraging nanobubbles (NBs) to create heterogeneous catalytic system. Our experimental results demonstrate an impressive increase (up to 80-folds) in degradation efficiency of micropollutants by peroxymonosulfate (PMS) at neutral conditions in the presence of NBs. We reveal that localized OH⁻ enrichment occurring on gas-liquid interface results in the alkaline microenvironment in neutral bulk solutions, which is the crucial driver for enhanced PMS activation. Through meticulous theoretical calculations, we identify that interfacial OH⁻ interact with free HSO₅^-via hydrogen bonds (i.e., H^HSO5-···O^OH-), lowering binding energy of peroxy bonds by 89 %, from 149.1 to 15.2 kJ/mol, triggering the generation of reactive species. Furthermore, the processes relying on NBs-enabled gas-liquid interface maintain persistent oxidative capacity, mineralizing 80-90 % of total organic carbon without neither NB nor PMS replenishment in 60 days. Overall, our study provides a fundamental insight into the catalytic oxidation processes at gas-liquid interface, and further guides the optimization of heterogeneous treatment processes.