Degradation of metformin in water using electro-Fenton process

Metformin has become an emerging contaminant in water compartments like many other pharmaceutical drugs. Moreover, conventional treatment methods are not enough to remove metformin in water. The use of advanced oxidation processes (AOPs) may be a solution to this problem. Electro-Fenton is an AOP that combines electrolysis and Fenton process to form reactive specie used to treat contaminants in water. The effects and optimum values of parameters for metformin degradation with electro-Fenton namely Fe2+ concentration, applied current, and pH were observed and gathered in this study, as well as rate constants of the degradation. The experimental solutions were contained in a continuously stirred vessel with boron-doped diamond as anode and carbon felt for the cathode. It was observed that the optimal values for each parameter are 0.1 mM for Fe2+ concentration, 300 mA for current, and pH=3. At these optimum conditions, a percent removal of 99.57 % was observed after 27 min of electrolysis. The value of the absolute rate constant (kabs) was found out to be (5.2658 +/- 0.0656) x 10(9) M-1 s(-1), which was calculated based on the competition kinetics and Vierordt's methods.