Degradation of diclosulam in water by corona plasma: role of reactive oxygen and nitrogen species

The recurrent presence of herbicides in water bodies highlights the need for technologies capable of promoting their efficient and sustainable degradation. In this study, diclosulam degradation in aqueous solution was investigated using corona discharge plasma at applied voltages of 5, 7.5, and 10 kV in ultrapure water, pH-adjusted water, and real water. Diclosulam concentration was determined by ultra-high-performance liquid chromatography coupled with mass spectrometry, while mineralization was evaluated by total organic carbon analysis. At 10 kV, diclosulam degradation reached 73.49%, accompanied by 73.83% total organic carbon removal. Performance was enhanced in an alkaline medium (pH 10), resulting in 94.93% degradation. In real water, degradation efficiency decreased to 57.75%, attributed to radical competition and the influence of matrix ions on reactive oxygen species (ROS) and reactive nitrogen species (RNS). Plasma treatment also reduced pH, increased electrical conductivity, and elevated nitrate (NO 3 − ) and hydrogen peroxide (H 2 O 2 ) concentrations, indicating the accumulation of measured long-lived reactive-species indicators during treatment. Sixteen transformation products were detected, supporting the proposal of plausible degradation pathways for diclosulam. Overall, corona plasma effectively promoted diclosulam degradation, particularly under alkaline conditions. These findings highlight the potential of this technology for treating herbicide-contaminated waters and support further optimization for real-world applications.