Electrochemical Degradation of Diuron in Chloride Medium using DSA® Based Anodes

This work presents a study of the electrochemical degradation of the herbicide diuron using Ti/RuxTi(1-x)O2 and Ti/IrxTi(1-x)O2 (x = 0.3, 0.5 and 0.7) anodes. The investigation of the degradation was conducted in the presence and in the absence of chloride. The study of the herbicide removal as a function of the current density in the absence of chloride yielded 41 and 49% COD (chemical oxygen demand) removals and 10 and 14% TOC (total organic carbon) removal at 100 mA cm(-2), respectively. By keeping the electrolysis time constant (4 h), Ti/Ru0.7Ti0.3O2 anode composition was determined as the most active for removal of diuron and its byproduct. The maximum removal value achieved after 4 h was 58%. Addition of chloride doubled the removal ratio, and 100% COD removal was obtained for Ti/Ru0.3Ti0.7O2. High-performance liquid chromatography (HPLC) analysis confirmed the total removal of the herbicide in chloride medium and indicated the formation of byproducts. The generated byproducts presented as function of the applied current density and the anode composition. Ir-based anodes promoted milder oxidation and furnished more byproducts in aqueous medium.