Plasma-bubble engineered cobalt oxide catalyst for efficient and sustainable removal of antibiotics from water

The widespread misuse and improper disposal of antibiotics have led to their persistent accumulation in aquatic environments, posing escalating threats of antimicrobial resistance. Non-thermal plasma (NTP) offers a promising route for antibiotic degradation via advanced oxidation, yet its efficiency remains hindered by the suboptimal activation of plasma-derived reactive species. Here, we report a dual-mode plasma bubble reactor that integrates spark discharge (SD) for catalyst activation and dielectric-barrier discharge (DBD) for in situ plasma bubble generation. Cobalt oxide pre-treated by SD mode of NTP (SPT-Co₃O₄), enriched with oxygen vacancies (OVs), was employed to catalytically enhance the conversion of plasma-generated ozone (O₃) into hydroxyl radicals (·OH), thereby unlocking the full oxidative potential of the system. Under optimized conditions, the SPT-Co₃O₄/DBD system achieved a 16.1% increase in ampicillin removal compared to DBD alone, along with a significant rise in the apparent kinetic rate constant, 23.2% improved total organic carbon (TOC) removal, a 16.1% enhancement in energy yield, and a 45.6% reduction in electrical energy per order (EEO). The SPT-Co₃O₄ demonstrated excellent stability and reusability over multiple cycles. Mechanistic insights derived from DFT calculations and radical quenching experiments confirmed the central role of ·OH generated through O₃ activation on oxygen vacancy-rich surfaces. This work establishes a robust plasma–catalytic interface that substantially advances the efficacy of NTP-based water treatment and offers a scalable solution for eliminating antibiotics and other micropollutants.