Enabling Aqueous Ozonation via Ozone Nanobubbles: Oxidative Modification of Activated Carbon and Its Performance and Economic Implications

Abstract Traditional adsorbent functionalization often relies on energy-intensive thermal oxidation or hazardous chemical reagents, hindering sustainable wastewater treatment infrastructure. This study introduces ozone nanobubbles (O3NBs) as a transformative, environmentally benign aqueous ozonation method for the precision surface modification of activated carbon. Utilizing a scalable hydrodynamic cavitation system, stable O3NBs (∼115 nm) were generated to induce surface-selective oxidation. Mechanistically, EDLVO theory and SEM analysis confirm that performance improvements are driven by the thermodynamic favorability of O3NBs’ attachment to the carbon surface. This stable adhesion enables direct delivery of encapsulated ozone to the carbon framework, facilitating localized oxidation that grafts oxygen-containing functional groups, such as hydroxyl, carbonyl, and carboxyl, while preserving the material’s essential bulk porous structure. This reagent-free treatment achieved a >30% enhancement in crystal violet adsorption capacity within 30–90 min. Life-cycle analysis demonstrates that O3NB processing reduces capital investment by 95% and energy costs by over 89% compared to conventional oxidation methods. As a pioneering application for material engineering, this technology offers a generalizable, ESG-compliant tool for the next generation of sustainable industrial wastewater treatment.