Investigation of Dye Removal Efficiency of the Photoelectrocatalytic System Using Graphite and Stainless Steel as Electrodes

The removal of Acid Orange 7 by the photoelectrocatalytic process was investigated at ambient temperature under solar irradiation using graphite as the cathode and stainless steel coated with the ZnO/TiO2 nanocomposite as the anode. The microstructure of the ZnO/TiO2 coated electrode was characterized by the SEM test. The results revealed dye and COD removal efficiencies of 99% and 97%, respectively, over a period of 360 minutes. The best performance was achieved in 360 minutes with no aeration at a current of 1 mA/cm2, an initial dye concentration of 100 mg/L, an electrode surface area of 30 cm2, and an electrolyte concentration of 0.01 M; energy consumption under these optimum conditions was 0.15 KWh/ppm. It may be concluded that the photoelectrocatalytic process is well capable of removing organic compounds, especially textile effluents containing dyes and non-degradable contaminants, due to its ability to produce hydroxyl radicals, superoxide, etc. Thus, the technique may be recommended for use as a pre-treatment process to reduce operational costs.