Abstract: Electrocoagulation (EC) is among the most effective techniques that remove color and decontaminate effluent. Coagulants are delivered in situ by anode corrosion. In this research, indigo dye removal using iron electrodes in continuous electrocoagulation process and the responsible species for decolorization were investigated. The Response Surface Methodology (RSM) was used to optimize the process parameters. The finding in this study shows that at fixed conductivity at 15,000 μS·cm^-1, the neutral conditions (pH from 6 to 8), the low absorbance, the low flow rate and the high voltage level enhance the color removal efficiency. The high R² value of 97.8% and ANOVA analyses show a good correlation between the experimental and predicted results. Under the optimum conditions, which are pH of 7.5, solution concentration of 60 mg·L^-1, inlet flow rate of 2 L·min^-1 and voltage of 47 V, the predicted decolorization of 94.083% was achieved at 93.972% with a total cost of 0.0927 USD·m^-3 of treated effluent. At the optimum pH (7.5), the zeta potential value (-4 mV) of the effluent during EC match with the one of iron Ⅲ hydroxide. The dye removal is ensured thanks to physical adsorption and flocculation. The results exposed in this work prove that the continuous electrocoagulation process could be successfully used for indigo dye removal at industrial scale.

Key words: Continuous electrocoagulation, Adsorption, Parameter estimation, Response surface methodology, Optimization, Zeta potential

摘要： Electrocoagulation (EC) is among the most effective techniques that remove color and decontaminate effluent. Coagulants are delivered in situ by anode corrosion. In this research, indigo dye removal using iron electrodes in continuous electrocoagulation process and the responsible species for decolorization were investigated. The Response Surface Methodology (RSM) was used to optimize the process parameters. The finding in this study shows that at fixed conductivity at 15,000 μS·cm^-1, the neutral conditions (pH from 6 to 8), the low absorbance, the low flow rate and the high voltage level enhance the color removal efficiency. The high R² value of 97.8% and ANOVA analyses show a good correlation between the experimental and predicted results. Under the optimum conditions, which are pH of 7.5, solution concentration of 60 mg·L^-1, inlet flow rate of 2 L·min^-1 and voltage of 47 V, the predicted decolorization of 94.083% was achieved at 93.972% with a total cost of 0.0927 USD·m^-3 of treated effluent. At the optimum pH (7.5), the zeta potential value (-4 mV) of the effluent during EC match with the one of iron Ⅲ hydroxide. The dye removal is ensured thanks to physical adsorption and flocculation. The results exposed in this work prove that the continuous electrocoagulation process could be successfully used for indigo dye removal at industrial scale.

关键词: Continuous electrocoagulation, Adsorption, Parameter estimation, Response surface methodology, Optimization, Zeta potential