Spatial Mapping of OH Radicals Produced by Electric Discharge in Hydrodynamic Cavitation Cloud

As strong oxidizers, OH radicals are crucial for water treatment applications involving plasma-liquid interactions. Hydrodynamic cavitation-based systems show promise for disinfection and micropollutant removal at flow rates of several m³/h. Knowledge of the spatial distribution of OH is limited. However, this is vital for enhancing system efficiency. This study maps the spatial distribution of OH generated by electric discharge in a hydrodynamic cavitation cloud. Using Luminol as a chemiluminescent probe, the study addresses challenges related to probe stability and luminescence lifetime in a dynamic cavitation environment. Luminescence decay time was assessed with a fast-frame camera, and spatial mapping was conducted by using an ICCD camera with an optical filter. Strong emission was observed at the collapsing end of the cavitation cloud and within the discharge channel, indicating the production and transport of OH into the liquid.