Electrochemical advanced oxidation of Atenolol at Nb/BDD thin film anode

Abstract Atenolol (ATN) is a drug commonly used and the fourth best-selling medicine in Brazil. As a consequence, it reaches the water bodies in the unmetabolized and metabolized forms, leading to toxicity. Aiming to avoid the high ATN discharge at the water bodies, its degradation was evaluated by electrochemical advanced oxidation process (EAOPs) using a boron-doped diamond thin film, supported on niobium (Nb/BDD), as anode. The influence of operational parameters, applied current density and initial pH were evaluated. The role of direct oxidation or of the oxidation mediated by hydroxyl radicals (HO ), persulfate ions (S 2 O 8 2− ) and sulfate radicals (SO 4 •− ) were studied. Inorganic and organic byproducts were detected and a pathway for ATN degradation was proposed. The results show that ATN can be degraded by direct or mediated oxidation by HO , S 2 O 8 2− and SO 4 •− . Depending on the applied current density and initial pH, ATN degradation pathway was changed, leading to different inorganic and organic byproducts. For higher applied current densities (20 and 30 mA cm −2 ), regardless of the initial pH, it was found total N-terminal group oxidation to NO 3 − . On the other hand, for lower applied current densities (5 and 10 mA cm −2 ) and initial pH of 10, there was no total oxidation of N-terminal group, leading to organic nitrogenated byproducts. EAOPs emerge as an option to ATN removal due to high mineralization and can be applied in a large pH range reducing chemicals for pH adjustment, with low energetic consumption.