Degradation of Organophosphate Pesticides Using Pyridinium Based Functional Surfactants

The enhancement of environmental quality is one of the key principles of sustainable agriculture, which points to less use of synthetic pesticides and chemical fertilizers. Green chemistry offers an array of innovative approaches to develop safe and efficient methods of chemical transformation toward nontoxic and readily biodegradable products under mild conditions. The development of new strategies for chemical decontamination of organophosphorus nerve agents and pesticides is an issue of immediate concern. Oximes have been demonstrated to find an application as functionalized organized molecular systems. In this study, kinetic investigations have been explored to estimate the nucleophilic efficiency of the oxime-functionalized pyridinium surfactants 3-hydroxyiminomethyl-1-alkylpyridinium bromide (alkyl = C_<i>n</i>H_2<i>n</i>+1, <i>n</i> = 10, 12, 14, 16) and 4-hydroxyiminomethyl-1-alkylpyridinium bromide (alkyl = C_<i>n</i>H_2<i>n</i>+1, <i>n</i> = 10, 12) for the hydrolysis of the pesticides paraoxon (NPDEP) and methyl paraoxon (NPDMP) in mixed micelles with the conventional cationic surfactants CPB, CTAB, and CDMEAB. Comprehensive study of the surface properties and acid–base equilibria of micellar systems composed of (i) functionalized surfactants and (ii) mixed functionalized/conventional cationic micelles has been carried out. The p<i>K</i>_a of studied nucleophiles in the presence of surfactants has also been monitored. The effect of pH, the comicellar effect of other surfactants, and the effect of alkyl chain length of functionalized surfactants have been monitored on the observed rate constants of cleavage of the studied organophosphates