Industrial potential of electro-oxidation and peroxymonosulfate coupling for efficient organic degradation in acidic dye wastewater

Abstract

Dye manufacturing wastewater contains high sulfuric acid and organic contaminants. Organic contaminants complicate treatment and hinder sulfuric acid recovery, causing environmental issues and resource waste. This study combines electro-oxidation with peroxymonosulfate (EO-PMS) to treat highly acidic (∼10 %) wastewater from Dispersed Violet 93 dye. Degradation was monitored in real time using a modified continuous-flow UV-Vis spectrophotometer. EO-PMS efficiently removes organic compounds, allowing the treated acidic liquid to be reused in dye production. At 16 mA/cm² current density and 10 mM PMS, complete degradation of 300 mL wastewater occurred within 6 minutes, achieving 86 % mineralization. Degradation follows zero-order kinetics, with mass transfer efficiency being a key factor. Experimental variables influencing degradation efficiency were also investigated. Free radical scavenging and electron paramagnetic resonance experiments identified ·OH as the main active species (83.6 %), with minor contributions from SO4·- (1.45 %) and others. Experimental data were used to fit the relationships between current intensity, PMS concentration, degradation time, and wastewater disposal costs to assess the economic feasibility of EO-PMS. This study presents an efficient, cost-effective degradation method with real-time monitoring, suitable for industrial-scale treatment and reuse of acidic dye wastewater.