Degradation of SDBS in water solutions using plasma in gas-liquid interface discharge: Performance, byproduct...

Sodium Dodecyl Benzene Sulfonate (SDBS) is a major anionic surfactant and is widely used in the detergent industry. The large amount of SDBS discharged into water bodies can cause eutrophication of water bodies and produce toxic effects in aquatic organisms. In this study, the degradation of SDBS and variation in toxicity during the plasma treatment process were evaluated using gas-liquid interface discharge. The experimental results showed that SDBS could be removed effectively after discharge for 8 min at an initial concentration of 30 mg/L. The SDBS removal could be fitted by the first-order kinetic model. The plasma voltage and initial pH had great effects on the removal of SDBS. At the same voltage, SDBS could be removed faster under alkaline conditions. Compared to ozonation, much higher SDBS and TOC removal performance was achieved by plasma treatment. HO, which was mainly derived from the reaction of H₂O₂ and ozone in the solutions, played a major role in the oxidation process. The toxicity evaluation showed that plasma treatment could reduce the acute toxicity effectively initially, and also indicated that the formed intermediates of formate, oxalate, malonate and sulfate had no negative effects. However, further treatment caused an increase in toxicity, which was mainly correlated with the excessive residual H₂O₂ formed during the plasma process. This study indicated that while applying plasma treatment, the conditions should be optimized comprehensively to maintain a low H₂O₂ residual in the effluent.