Metal ion promoted degradation mechanism of chlorpyrifos and phoxim

This study evaluate the degradation of the two organophosphorus pesticides: chlorpyrifos and phoxim in the presence of Ag+ at fixed initial concentration and temperature. Chlorpyrifos and phoxim were used as model compounds to develop experimental methods for the investigation of kinetic and degradation pathways. In order to determine what metabolites will be formed after degradation we used 31P NMR. Chlorpyrifos and phoxim were found to degrade in the presence of Ag+ and the result shown in lower chlorpyrifos to Ag+ ratio (<8), only one product formed and its concentration increased versus time. Degradation of chlorpyrifos and phoxim in methanolic solution in the presence of Ag+ followed first-order exponential decay kinetics, and the half-life (t1/2) of chlorpyrifos and phoxim are 693 and 1155, respectively.