Response surface optimization of electrocoagulation to treat real indigo dye wastewater

Abstract

This research aimed to optimization of the electrocoagulation process was investigated in terms of chemical and physical mechanisms using Box-Behnken response surface design (BBD). The experimental conditions were optimized by examining the interaction effects of initial pH, electrolysis time, and current density on COD and color removal efficiencies. The results showed that the calculated response functions agreed well with the experimental data, where R2 = 94.87% for COD and 97.86% for color. An ANOVA analysis revealed p-values lower than 0.05 at the 95% confidence interval (CI) (p = 0.05), confirming that the quadratic models were statistically significant and supportive of the phenomenon study on COD and color removal. According to BBD results, for the maximum removal of COD and color, the optimal independent variables were a pH of 4.0, electrolysis time of 60 min, and current density of 300 A/m2. Predicted removal efficiencies of COD and color under optimal operating conditions were 71.96% and 96.38%, respectively. Three experiments conducted to confirm optimal operating conditions revealed mean values of COD and color removal efficiency to be 73.13% and 94.68%, respectively. These findings confirmed that predictions of optimal operating conditions generated by the response surface design model were reliable.