Anodic oxidation as promoting technology for treatment and reuse of industrial textile effluent using ruthenium-doped lead dioxide (PbO₂) anode

In this study, a novel modified lead PbO₂ with ruthenium (Ru) was used to evaluate the efficiency of the anodic oxidation (AO) process on the degradation of real effluent produced by the Tunisian textile industry. Investigation of PbO₂ anodes modified with different concentrations of Ru (0 M to 0.025 M) using X-ray diffractometry reveals the presence of β form, compared to those detected with undoped PbO₂ anode. The β-PbO₂ is porous, providing a larger active surface area for the degradation of organic compounds. The linear polarization measurements for the modified electrodes show that with the decrease in ruthenium concentration, the oxygen evolution potential was enhanced and increased. The contact angle analysis revealed an enhancement in the hydrophobicity of the modified PbO₂ electrode, which can increase the surface adsorption of hydroxyl radicals (^·OH) on the anode surface. This suggests that effective improvements could be made to the electrode’s stability and catalytic activity. Moreover, the color removal, Chemical Oxygen Demand (COD) removal, and electric energy consumption (EEC) of real effluent stored in a homogenization basin reached up to 100%, 93%, and 6.5 kWh (kg COD)⁻¹, respectively, using PbO₂-Ru (0.01 M) after 300 min of treatment. The obtained results indicated that the AO is considered an appropriate and sustainable technology in the textile sector, thanks to its capability to produce treated wastewater that is reusable in different applications, fitting with national standards related to discharge and reuse in the context of water scarcity and climate change. The relative low cost of the modified electrode and its environmental benefits promote its real application as a sustainable industrial local wastewater management solution.