Treatment of an aqueous pesticides mixture solution by direct and indirect electrochemical advanced oxidation processes

Abstract

In the present work, a comparative study on the degradation of a mixture of three pesticides (chlortoluron, carbofuran and bentazon) has been carried out by electrochemical advanced oxidation processes such as anodic oxidation and electro-Fenton using boron-doped diamond (BDD) anode. These processes are based on the in situ production of hydroxyl radical, a highly strong oxidant, which allows the degradation of organic pollutants until their mineralisation into CO₂ and H₂O. Obtained results showed that more than 90% of TOC removal was obtained in 4 h of treatment by both processes. The mineralisation rate was found to be higher for electro-Fenton (BDD) than that of the anodic oxidation. Also, the electro-Fenton (BDD) can mineralise the pesticide solution in 90 min while anodic oxidation requires 150 min. The released inorganic ions, such as chloride, nitrate, sulphate and ammonium, are identified and their kinetic evolution was measured by ion chromatographic analyses.

Keywords:

• pesticides
• anodic oxidation
• electro-Fenton
• BDD anode
• hydroxyl radical, advanced oxidation processes