Parameter optimization of the chloride mediator-based electrochemical advanced oxidation process for the treatment of commercial azo dyes and actual dyeing effluent

This work focused on the development of an electrochemical system for direct and indirect electrochemical advanced oxidation process (EAOP) with a chloride mediator by electrogenerated active species for the degradation of unused toxic azo dye molecules of textile wastewater and the connection between cathodic and anodic processes. The experiments were carried out in a batch electrochemical cell for the degradation of Direct Red 1 (DR 1) and Reactive Orange 14 (RO 14) dyes. Eight different combinations of iron (Fe), stainless steel (Ss), copper (Cu), and graphite (Gr) electrodes were utilized as the cathode and anode. The influences of effluent initial concentration, pH, supporting electrolyte concentration, temperature, inter-electrode distance, current density, agitation rate, retention time, and radical scavengers on dye degradation have been critically examined. The optimum conditions were obtained at the monopolar-parallel (MP-P) connected electrodes (Gr- Ss) with 7.0 pH, 7.25 V voltage, 0.4 A current, 353 A/m 2 current density, 1 g/L NaCl, and a distance of 3 cm between the electrodes. Under these conditions, the removal efficiency reached 95.6% within 60 min of operation. Additionally, a multiple regression analysis was performed to assess how operating conditions affected the effectiveness of dye removal. The actual textile wastewater was examined as well, and the results revealed significant decolorization. Finally, due to its great capacity, the EAOP system is a promising large-scale technique for treating dye-contaminated effluents. Graphical Abstract Highlights Lemon leaves and peel are characterized by their highest observed antioxidant activity. Maceration serves to maintain the antioxidant effectiveness of LEO. Limonene (D/L) and Z-citral are noted for their exceptional antioxidant properties.