Electrochemical decolorization of textile dyes and removal of metal ions from textile dye and metal ion binary mixtures

The electrochemical textile dye decolorization and removal of metal ions from [textile dye|metal ion] binary mixtures of [AB29|Cu(II)], [RR2|Cu(II)], [AR97|Ni(II)], and [RB4|Ni(II)] were investigated using iron anodes and Na2SO4 electrolyte in a batch electrochemical reactor. The independent parameters of current density, electrolyte concentration, initial solute concentrations, and reaction temperature were operated in the range of 0.8–4.0 mA/cm2, 0–2 g/L, 0–400 mg/L, and 25–45 °C, respectively. The experimental data were optimized using response surface methodology (RSM), the approximation functions were obtained and the optimum operating conditions for the electrochemical decolorization and metal ions removal from [textile dye|metal ion] binary mixtures were determined. The quadratic models for textile dye decolorization and metal ion removal responses were well satisfied the assumptions of the analysis of variance (ANOVA). At optimized reaction conditions, the operating regions were determined for the efficiencies over 95% textile dye decolorization along with metal ion removal in [AB29|Cu(II)], [RR2|Cu(II)], [AR97|Ni(II)], and [RB4|Ni(II)] binary mixtures. The mean energy consumption values were evaluated between 29.2–38.1 kWh/kg dye decolorization and 14.2–22.5 kWh/kg metal ion removal at response surface optimized operating conditions.