Degradation of atrazine in aqueous solution with electrophotocatalytic process using TiO2−x photoanode

• The EPC process combined electrochemical oxidation, photolysis and photocatalysis.
• TiO2−x was prepared by means of a radio frequency (13.56 MHz) magnetron sputtering process.
• The developed EPC treatment allowed the oxidation of ATZ in water up to 99.2 ± 0.2%.
• Dechlorination of ATZ and chlorinated intermediates were almost completed after 180 min.
• The possible pathways of ATZ degradation by HO
• during the EPC treatment were proposed.

The present study investigates the efficiency of a sustainable treatment technology, the electrophotocatalytic (EPC) process using innovative photoanode TiO2−x prepared by a magnetron sputter deposition process to remove the herbicide atrazine (ATZ) from water. The coexistence of anatase and rutile were identified by X-ray diffraction (XRD) and the presence of oxygen vacancies reduce the value of the observed bandgap to 3.0 eV compared to the typical 3.2 eV TiO2, this reduction is concomitant with a partial phase transition which is probably responsible for the increase in photoactivity. The experimental results with an initial concentration of ATZ (100 μg L−1) show that more than 99% of ATZ oxidation was obtained after 30 min of treatment and reaction kinetic constant was about 0.146 min−1. This good efficiency indicates that EPC process is an efficient, simple and green technique for degradation of pesticides such as ATZ in water. The analysis with liquid chromatography technique permits to identify, quantify and see the evolution of ATZ by-products which are generated by dechlorination, dealkylation and alkylic-oxidation mechanisms. Finally, the possible pathways of ATZ degradation by hydroxyl radicals were proposed.