Development of magnetite modified graphite electrode: Application in electro-Fenton process for degradation of antidiabetic drug metformin hycloridate

• Degradation of metformin by the electro-Fenton process in aqueous and synthetic matrix. • Electrocatalytic improvement of graphite electrode from magnetite impregnation. • Monitoring of electrogenerated oxidizing agents in the electro-Fenton process. • The kinetic evolution of degradation was represented by the pseudo-first order model. • Lower ecotoxicological effect after metformin treatment in aqueous solution. Metformin hydrochloride (CMTF) is a widely used antidiabetic medication. However, the increase in its consumption combined with the fact that only 10 % of the drug is metabolized by the body, can promote contamination of the aquatic environment. Thus, the objective of the work was to develop a modified graphite electrode impregnated with magnetite, not yet reported in the literature, and apply it in the treatment of the drug CMTF via electro-Fenton. The higher degradation percentage obtained for the aqueous solution (AS) was 83.55 %. The developed electrode was applied in the treatment of synthetic effluent (SE) leading to 65.69 % degradation. Furthermore, the degradation of the drug, in both matrices, follows pseudo-first order kinetics and that at the end of the kinetic monitoring, 96 % and 66 % degradation was obtained for the AS and SE matrices, respectively. Furthermore, SE after treatment showed a reduction of 56.41 %, 39.04 % and 37.14 % for COD, BOD and TOC, respectively. Finally, it was verified that for the aqueous solution before and after treatment there was no toxicity. Thus, it can be stated that the treatment using the proposed electrode has the potential for drug degradation in different matrices.