Sustainable Degradation of Methyl Violet by Plasma Bubbling Array: Performance, Degradation Pathway, and Potential Toxicity

A plasma bubbling array (PBA) reactor was used to degrade methyl violet (MV) dye, and the effects of input voltage, frequency, and treatment time on MV removal were investigated. Through experimental methods and response surface methodology (RSM), the interactional influences between three parameters were examined. In the actual experiments, when the discharge voltage was set to 4.0 kV and the treatment time was 12 min, the PBA reactor exhibited a high degradation rate (96.15%) and notable energy efficiency (3.16 g/kWh). Under the optimal simulation parameters, the predicted degradation rate of MV is maximized at 98.32%, with only a 2.17% deviation from the actual value. Subsequently, the results of reactive oxygen and nitrogen species (RONS) analysis indicate that superoxide radicals (·O 2 − ) and ozone (O 3 ) have the greatest impact on MV degradation. The degradation pathway analysis and toxicity evaluation experiments of the solution before and after treatment showed that the toxicity of the solution decreased with the extension of reaction time, and the treated solution may be beneficial to seed germination. Overall, these findings provide valuable insights into the use of plasma technology for the efficient, economical, and sustainable removal of dyes from water.