Techno-economical aspects of electrocoagulation optimization in three acid azo dyes’ removal comparison

Abstract

This study compares the optimization models for three acid azo dyes removal by electrocoagulation (EC). First, Response Surface Methodology (RSM) models were evaluated and compared via four independent parameters, including initial pH (4–10), initial dye concentration (0–600 mg/L), current density (41.67–291.66 A/m2), and reaction time (3–15 min). Then, second-order polynomial equations of dye removal and operating cost models were separately applied as benefit and cost functions in the two-objective Imperialist Competitive Algorithm (ICA), respectively. According to the statistical analysis, not all the parameters are essential in removal efficiency for the three selected dyes. For example, the initial dye concentration and current density were the effective independent parameters in the Acid Red 18 removal model. According to the Pareto solutions, by changing the operating cost function from US$/m3 to US$/Kg removed dye, the difference between the Pareto curve points of Acid Brown 14 and Acid Orange 7 decreased significantly. Therefore, the unit of operating cost and dye type can affect the treatment policy in practice. The two-objective optimization showed an RSM deficit in predicting some corner points as previously depicted in RSM main effect plots.