APPLICATION OF ADVANCED OXIDATIVE ELECTROCHEMICAL PROCESSES (AOEP’s) IN THE TREATMENT OF PHARMACEUTICAL EFFLUENTS USING DDB ANODE
Pharmaceutical effluent. Advanced Oxidative Processes. DDB anode
In this study, the anhydrous oxidation processes with in situ electrogeneration of hydrogen peroxide (AO-H2O2) and Electro-Fenton (EF) were used to decontaminate two synthetic effluents containing caffeine and metformin hydrochloride (MET). The former is the most commonly used compound in the general population and the latter is used to treat type II diabetes. The anode using was DDB boron doped diamond. Process efficiency was evaluated by UV-vis, COD, COT and HPLC spectroscopy. To optimize the processes, the influence of operating parameters such as support electrolyte concentration, drug concentration, current density (15, 30 and 60 mA cm-2) and initial pH (3.0) were studied. Maximum caffeine removal, chemical oxygen demand (COD) reached 92% and 53% after 360 min of electrolysis at initial pH 3 for EF and AO-H2O2, respectively, with the initial caffeine concentration being 100 mg L-1 with constant current density of 30 mA cm-2 with 0.05 mol.L-1 Na2SO4 electrolyte. Regarding MET, it was possible to notice that the increase of the applied current density also favored the removal using AO-H2O2, but there was no complete degradation even at 60 mA cm-2 and maximum electrolysis time. With EF the results were better with over 97% removal while OA-H2O2 had only 85% removal. Failure to completely remove MET implies that the compound is more recalcitrant than caffeine and therefore difficult to degrade