Abstract
Advanced oxidation processes (AOPs) are considered as a promising remediation technology for water treatment due to the fast decomposition rate and environmental friendly. Generally, the advanced oxidation processes refer to methods generating OH radicals in water for the decomposition of persistent organic pollutants. However, since the lifetime of OH radicals is considerably short, they need to be generated and react with other pollutants simultaneously in water or near the water surface. Discharges in multiphase environments such as discharges inside bubbles in liquids attract attentions for the easy discharges in a gas phase and the simultaneous diffusion of OH radicals from bubble to liquids through bubble interface just after generating. A discharged bubble jets system has been constructed to investigate the decomposition ability for acetic acid by generating OH radicals inside nanosecond pulse discharged bubbles. However, the complex generation and diffusion processes of chemical radicals are still unclear in the experiment. Therefore, the purpose of this research is to clarify the physicochemical factors which are favorable for the generation of OH radical in water by a discharged bubble. A two-dimensional plasma-liquid two-phase model for a nanosecond pulse discharged bubble is developed by considering chemical reactions in liquid phase as well as the diffusion from bubble to liquid. It is found that OH radicals can diffuse to only several micrometers in liquid from bubble interface and are most generated under low applied voltage and high frequency conditions.
