Electro-Advanced Oxidation of Reactive Orange 84: Effects of PbO 2 /Graphite Anode Fabrication Conditions

This study presents the fabrication of a (PbO 2 /graphite) anode under varying conditions and optimization of reactive orange 84 dye degradation using Box–Behnken design. Under the optimized fabrication conditions, 0.19 M lead nitrate, 37.49 mA cm −2 current density, and 1.5 h time, the anode achieved 78.27% dye degradation and a deposition weight of 10.56 g at an operational current density of 6 mA cm −2 , electrode spacing of 1.5 cm, and solution pH of 3. After 1 h of electrolysis, a COD removal efficiency of 72% was obtained. Notably, the electrical energy consumption per gram of COD removed was only 0.008 kWh (g COD) −1 , while the treatment cost was as low as 0.96 $ (kg COD) −1 , outperforming many previously reported PbO 2 -based studies. SEM analysis revealed overlapping tetrahedral and angular PbO 2 grains, and EDS confirmed the elemental composition as 11.84 wt% oxygen and 88.16 wt% lead. XRD results showed a mixed coating containing 25.94% α -PbO 2 (16.27 nm) and 74.06% β -PbO 2 (13.83 nm), with the β -phase dominating the electrocatalytic behaviour. LSV analysis indicated a high oxygen evolution potential of 1.90 V, suppressing unwanted side reactions, oxygen evolution. Overall, the optimized PbO 2 /graphite anode demonstrates excellent catalytic activity and energy efficiency, applicable for wastewater treatment.