Degradation of some organophosphorus pesticides in aqueous solution by gamma irradiation.

This study reviews the effect of different gamma radiation doses (1, 3, 5, 10 and 20 kGy) on the degradation of chlorfenvinphos, diazinon, dimethoate, and profenofos at different concentrations (0.5, 1.0, and 5 μg/mL) in aqueous solutions (deionized, tap, and groundwater). The role of initial concentration, measured total dissolved solids and pH on degradation was investigated. The degradation of the four tested organophosphates due to gamma irradiation was determined using LC-MS/MS. The radiolytic degradation products were studied using the scan mode of GC-MS/MS. The radiation chemical yield, dose constant, D0.5, and D0.9 were calculated to evaluate degradation efficiency for each compound. All pesticides are completely eliminated, despite water type, at low concentration levels of 0.5 and 1 μg/mL. At concentration level 5 μg/mL, gamma irradiation could completely remove pesticides concentration in de-ionized water, but the binding effect of total dissolved solids decreased degradation efficiency of some organophosphates such as diazinon. The D0.9 of 5 μg/mL concentration of chlorfenvinphos, diazinon, dimethoate, and profenofos in de-ionized water were 6.6, 8.7, 11.0, and 17.6 respectively. Also, Gamma irradiating of an agriculture wastewater sample resulted in the removal of carbaryl, carbosulfan, and diazinon at 6 kGy dose.