Chlorpyrifos is an
organophosphate pesticide and is significant because of its extensive use, persistence in the environment, wide distribution, and its toxicity may lead to lung and central nervous system damage, developmental and autoimmune disorders and
vomiting. In the present study, the irradiation of
chlorpyrifos in aqueous
solution by (60)Co γ-rays was conducted on a laboratory scale and the removal efficiency of
chlorpyrifos was investigated. The
SPME-GC-ECD method was used for analysis of
chlorpyrifos. Aqueous solutions of different concentrations of target compound (200-1000 μg L(-1)) were irradiated through 30-575 Gy. Gamma irradiation showed 100% degradation for a 500 μg L(-1)
solution at an absorbed dose of 575 Gy (the dose rate was 300 Gy h(-1)). The radiolysis of
chlorpyrifos was pseudo-first order (decay) with respect to dose. The dose constants determined in this study ranged from 8.2×10(-3) to 2.6×10(-2) Gy(-1), and decreased with an increase in the initial concentration of
chlorpyrifos, while the radiation chemical yield (G-value) for the loss of
chlorpyrifos was found to decrease with increasing absorbed dose. The effect of saturated solutions of N2 and N2O, and radical scavengers
tert-butanol, iso-
propanol, H2O2, NaNO3 and NaNO2 on the degradation of
chlorpyrifos were also studied. The results showed that the oxidative
OH was the most important in the degradation of
chlorpyrifos, while the reductive radicals, aqueous electron and H, were of less importance for the degradation of
chlorpyrifos. The inorganic by-products Cl(-), SO4(2-) and PO4(3-) were quantitatively determined by IC.