Comparison and statistical analysis for post-tanning synthetic wastewater degradation using different electrochemical processes

Experimental variables to optimize several electrochemical advanced oxidation processes (EAOPs), used to carry out the degradation of 0.15 L of the tannery dyes Violet RL and Green A, at 30, 50 and 80 mg L⁻¹ in 0.05 M Na₂SO₄ of pH 3.0, have been determined from a factorial design analysis of ANOVA variance. Trials were performed with a stirred tank reactor using Boron Doped Diamond (BDD) as a working electrode. The dyes were removed via free hydroxyl radicals (O^[rad]H), formed at the BDD anode from water oxidation and combined with Fenton's reaction, cathodically produced with hydrogen peroxide (H₂O₂). Factors were the current density of EAOP type, an initial dye concentration, and of dye type, i.e. violet, green and its mixtures. This research highlights the interaction between factors and its impact on the removal, kinetic behaviour and operational costs, which presents the likeness of the electrochemical/BDD-based process for the degradation of industrial dyes, established in wastewaters under suitable experimental conditions and the first kinetic loss stage. Under these conditions, close to 100 %, the color abatement was obtained.