Electrocatalytic Effect of IrO_2/Ta_2O_5 Ti and RuO_2/Ta_2O_5 Ti in the Oxidation of Amoxicillin in Aqueous Medium

摘要

Titanium electrodes coated by transition metal oxides have been used in many applications, thus they remain the subject of constant research and improvement. One of the most important applications for this type of electrode is the electro-generation of hydroxyl radicals (*OH), via catalytic water oxidation, during the electrochemical degradation of organic compounds. In this sense, the intention of this study was the development of modified surfaces by transition metal oxides (IrO_2/Ta_2O_5||Ti with Ir:Ta 70:30 and 30:70; and RuO_2/Ta_2O_5||Ti with Ru:Ta 70:30 and 30:70) for electrochemical advanced oxidation processes (AOP) to degrade organic micropollutants, specifically amoxicillin (AMX). The characterization of the surface morphology and composition of the different anodes used in this study was made by Scanning Electron Microscopy (SEM) - Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Photoelectron Spectroscopy (XPS) and electrochemical characterization; the last one was carried out by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Additionally, the indirect detection of *OH generated on the surface of the electrode was done by UV-Vis spectrophotometry using coumarin. The corresponding degradation was carried out by electrolysis of AMX in an aqueous medium applying a current of 15 mA, where the amoxicillin concentration was measured throughout by High Performance Liquid Chromatography (HPLC) - UV-Vis, obtaining efficiencies of more than 90% AMX degradation in 0.1 M Na_2SO_4 after 400 min. The Carbon Organic Demand (COD) removal was also measured, obtaining up to 80% removal using the same experimental conditions in presence of IrO_2/Ta_2O_5||Ti 70:30 by the major generation of *OH than using RuO_2/Ta_2O_5||Ti 30:70.