Investigation on the performance of plasma microreactor with cavitation channel for the oxidation degradation of methylene blue

Abstract

Ozonation degradation has attracted extensive attention due to its effectiveness in oxidizing organic pollutants. As a typical ozone (O₃) generator, the plasma microreactor generates active oxygen species by ionizing gas-liquid streams in microchannels. However, insufficient mixing occurs between reactive oxygen species in the gas phase and the liquid phase due to the uniform width of the flow channel. Thus, a newly plasma microreactor with a cavitation channel was conceived to induce cavitation effects and increase the O₃-liquid mass transfer intensity. The influence of three channel geometries on cavitation performance was clarified by fluid dynamic simulations. The hyperbolic channel showed higher cavitation intensity than the cylindrical and conical channels. By examining the effects of initial concentration, initial pH, inlet flow rate, and input voltage on the ozonation degradation of methylene blue, the optimal operating conditions were identified. Under optimal conditions, the plasma microreactor with a hyperbolic channel achieved a significant degradation rate of 95.7 % within 10 min. This work presents a new type of microreactor for the efficient degradation of dye pollutants.