Photocatalytic treatment of water soluble pesticide by advanced oxidation technologies using UV light and solar energy

Advanced oxidation technologies (AOTs) using UV lamps and solar radiation were investigated for treating aqueous solutions of pesticide (Vydine). One group of experiments was conducted using UV light irradiated at wavelengths of 254 nm (UV254) and 350 nm (UV350). Another similar group was conducted using solar radiation incident during the months of March (Sol-Mar) and June (Sol-Jun). Experimental measurements of pesticide concentration, TOC mineralization, COD and BOD were monitored and recorded.Results showed that AOTs with (UV254) irradiation or (Sol-Jun) solar radiation were more efficient than those with (UV350) or (Sol-Mar) irradiations. Pesticide eliminations achieved by using UV254 and Sol-Jun were 50% and 32%, respectively, while the maximum Vydine elimination achieved by UV350 or Sol-Mar was 20%. The use UV254 with photo-Fenton increased the pesticide elimination to more than 95%.Photo-degradation rates of Vydine in the presence of TiO2 followed the order of UV254 > Sol-Jun > Sol-Mar > UV350. The photo-catalytic reactions of pesticide followed pseudo first-order kinetics. The calculated rate constants were 0.015, 0.012, 0.009 and 0.0065 min−1 when using UV254, Sol-Jun, Sol-Mar and UV350, respectively. Degradation processes examined under the conditions of the present work were able to mineralize the pesticide (Vydine) totally and/or to improve the treated solution biodegradability. Photo-Fenton and TiO2 mineralized all the organic matter content from the solution in 230 min. Moreover, BOD5 was increased from 0 to 9 mg O2/L when UV254 irradiation was only used and increased to 50 mg O2/L following the use of photo-Fenton treatment.