A comparison study of methyl green removal by peroxi-coagulation and peroxi-electrocoagulation processes

Abstract

This work compares for the first time the efficiency of peroxi-coagulation (PC) and peroxi-electrocoagulation (PEC) methods for the removal of methyl green (MG) stains from aqueous solutions. Lab-scale, batch electrochemical cells made of an iron anode and porous graphite cathode were used in both processes. In addition, this work aims to identify the optimum operating conditions that resulted in the highest possible removal of MG. Several parameters were investigated such as effect of pH (1–9), temperature (15–60 °C), current density (5–35 mA/cm2), reaction time (10–90 min), electrode gap (1–3 cm), H2O2 concentration (750–900 mg/L, for PEC only), and air aeration (1–3 L/min, for PC only). The results show that both pH and current density have a great influence on MG eliminating efficiency, which implies that the removal processes are controlled by the reaction conditions in the bulk of the solution. The optimum conditions were found to be an initial value of pH equal to four, current density of 10–15 mA/cm2, air aeration equal to two L/min, and reaction time duration of 40–50 min. Maximum MG removal of 98.65% and 99.89% were achieved by PC and PEC, respectively, at the optimum operation values. Experimental data were fitted to 1st-order, 2nd-order, and power law models. This work shows the superior of PEC in the removing of MG from aqueous solutions.