Considerable interest has been shown in recent years towards utilizing TiO2 particles as a photocatalyst in the degradation of harmful organic contaminants.
In this study, photocatalytic degradation of diazinon which is extensively used as a pesticide in the agriculture field, has been investigated with UV-illuminated TiO2 in aqueous suspension as a function of the following different experimental parameters : initial concentration of diazinon, TiO2 weight, UV wavelength, pH of the solution.
Photodegradation rate increased with decreasing initial concentration of diazinon and with increasing pH of the solution. Photodegradation rate increased with increasing TiO2 weight, but was nearly the same at TiO2 weight of 1 g/ℓ , 2 g/ℓ , i.e., for initial diazinon concentration of 5 ㎎/ℓ . UV wavelength affecting on the degradation rate of diazinon decreased in the order of 254 nm > 312 nm > 365 nm. For TiO2 weight of 1 g/ℓ and initial diazinon concentration of 5 ㎎/ℓ , the photodegradation removal of diazinon was 100% after 130 min in the case of 254 nm, but 95% in the case of 312 nm, and 84% in the case of 365 nm, after 180 min. The photodegradation of diazinon followed a first order or a pseudo-first order reaction rate. For initial diazinon concentration of 5 ㎎/ℓ , the rate constants(k) in UV and TiO2(1g/ℓ )/UV system were 0.006 min-1 and 0.0252 min-1 at 254 nm, 0.0055 min-1 and 0.0104 min-1 at 312 nm, and 0.004 min-1 and 0.0092 min-1 at 365 nm respectively.

• 류성필(제주대학교 환경공학과) | Seong Pil Ryu
• 오윤근(제주대학교 환경공학과) | Youn Keun Oh