LAUSR

This paper discusses a systematic study of Congo red dye removal by electrocoagulation process with an aluminium electrode pair. The statistical modelling technique, response surface methodology is used for the design of experiments. The various operating parameters chosen are reaction time (10–60 min), initial dye concentration (20–80 mg/L), pH of the solution (5–11) and the applied voltage (5–20 V) with removal efficiency and energy consumption as responses. The results show the leading role of various parameters on maximizing removal efficiency and minimizing energy consumption, and the optimum conditions obtained are initial dye concentration of 65 mg/L, solution pH of 9.5, the reaction time of 25.08 min and an applied voltage of 8.75 V. According to the experimental results, the maximum removal efficiency obtained is 89.344% with an energy consumption of 9.4589 W h. The analysis of variance (ANOVA) results in a regression coefficient of 0.9701 and 0.9993 for removal efficiency and energy consumption, respectively, and it indicates only 0.29% and 0.01% chance of deviation for the developed model from the actual operating conditions. The various characterization results affirm the removal of dye with in situ formed coagulants of aluminium by adsorption and charge neutralization mechanism. The kinetic study reveals that the pseudo-second-order model is the best-fitted model for the removal of Congo red dye.