Ozone Micro–Nanobubbles: Properties, Effects, and Applications

Ozone micro- and nanobubbles have emerged as a promising platform for advanced oxidation processes owing to their distinctive physicochemical characteristics, including exceptional stability, prolonged gas residence time, and highly active gas–liquid interfaces. Compared with conventional ozonation, micro/nanobubble-assisted systems significantly enhance ozone dissolution and utilization efficiency. They achieve this by creating a unique interfacial microenvironment that promotes localized and sustained oxidative reactions. Increasing evidence suggests that ozone oxidation is not dominated solely by homogeneous bulk-phase reactions but is strongly coupled with processes occurring at the bubble/water interface, particularly hydroxyl radical generation and surface-localized oxidation. This review provides an application-oriented overview of ozone micro/nanobubble technology by summarizing representative preparation methods and characterization techniques, elucidating their distinctive interfacial physicochemical properties, and critically examining their performance in oxidative cleaning, microbial inactivation, and complex environmental remediation. Special emphasis is placed on interpreting these phenomena from the perspective of gas–liquid reactions and surface-induced radical generation, with the aim of establishing a unified mechanistic framework that bridges fundamental properties with engineering performance. Finally, current challenges and future research directions for translating ozone micro/nanobubble systems into large-scale and long-term applications are discussed.