Aeration-Free In Situ Fenton-like Reaction: Specific Adsorption and Activation of Oxygen on Heterophase Oxygen Vacancies

Aeration accounts for 35-51% of the overall energy consumption in wastewater treatment processes and results in an annual energy consumption of 5-7.5 billion kWh. Herein, a solar-powered continuous-flow device was designed for aeration-free in situ Fenton-like reactions to treat wastewater. This system is based on the combination of TiO_2-x/W₁₈O₄₉ featuring heterophase oxygen vacancy interactions with floating reduced graphene/polyurethane foam, which produces hydrogen peroxide in situ at the rates of up to 4.2 ppm h^-1 with degradation rates of more than 90% for various antibiotics. The heterophase oxygen vacancies play an important role in the stretching of the O-O bond by regulating the d-band center of TiO_2-x/W₁₈O₄₉, promoting the hydrogenation of *·O₂^- or *OOH by H⁺ enrichment, and accelerating the production of reactive oxygen species by spontaneous adsorption of hydrogen peroxide. Furthermore, the degradation mechanisms of antibiotics and the treatment of actual wastewater were thoroughly investigated. In short, the study provides a meaningful reference for potentially undertaking the "aeration-free" in situ Fenton reaction, which can help reduce or even completely eradicate the aeration costs and energy requirements during the treatment of wastewater.