New perspectives to enhance the electro-oxidation of atrazine in methanol medium: Photo assistance using UV irradiation

There has been a considerable increase in the use of herbicides worldwide, and this has resulted in the contamination of soil and water bodies. The presence of large volumes of water limits the direct application of electrochemical treatment when the pollutants are present in low concentrations; this limitation can be cir-cumvented by using pre-concentration techniques via adsorption and desorption with organic solvent. Taking this into account, the present study sought to investigate atrazine (ATZ) degradation through the application of photocatalysis (PC) and photo-assisted electrocatalysis (PAEC) in methanol medium using mixed metal oxide anode. The application of PC and PAEC in pure methanol led to nearly 92 % and 98 % of ATZ removal, respectively. The addition of water in the methanol medium under the PAEC technique led to better pollutant removal, where an increase was observed in ATZ removal from 97.2 % in pure methanol and 99.2 % in methanol containing 10 % of water (methanol/10 % H2O). Furthermore, the application of PAEC yielded higher kinetic constants (k), where an increase of up to 74.7 % and 49.4 % in k was obtained for pure methanol and methanol/ 10 % H2O, respectively. Variations in energy consumption (EC) were observed when PAEC was applied for ATZ degradation via the media investigated; the use of pure methanol and methanol/10 % H2O led to EC of 0.219 and 0.183 kW h m- 3 %-1, respectively, in one hour of experiment. Finally, changes in the analytical technique and reaction medium led to variations in the by-products formed, where the formation of some by-products was favored over others due to differences in the oxidizing species generated in the process. The results obtained show that the application of PAEC in methanol is a highly promising technique for the treatment of effluents.