Montmorillonite Functionalized with Pralidoxime As a Material for Chemical Protection against Organophosphorous Compounds

Montmorillonite K-10 functionalized with a-nucleophilic 2-pralidoxime (PAM) and its zwitterionic oximate form (PAMNa) is introduced as a versatile material for chemical protection against organophosphorous (OP) compounds such as pesticides and chemical warfare agents (CWA). Upon inclusion into the montmorillonite interlayer structure, the pyridinium group of PAMNa is strongly physisorbed onto acidic sites of the clay, leading to shrinking of the interplanar distance. Degradation of diethyl parathion by PAMNa-functionalized montmorillonite in aqueous-acetonitrile solutions occurred primarily via hydrolytic conversion of parathion into diethylthio phosphoric acid, with the initial stages of hydrolysis observed to be pseudo-first-order reactions. Hydrolysis catalyzed by the clay intercalated by PAMNa was 10- and 17-fold more rapid than corresponding spontaneous processes measured at 25 and 70 degrees C, respectively. Hydrolytic degradation of diisopropyl fluorophosphate (DFP), a CWA simulant, was studied on,montmorillonite clay functionalized by PAMNa and equilibrated with water vapor at 100% relative humidity by (31)P high-resolution magic angle spinning NMR and was observed to be rather facile compared with the untreated montmorillonite, which did not show any DFP hydrolysis within 24 h. The incorporation of the functionalized clay particles into elastomeric film of polyisobutylene was shown to be a means to impart DFP-degrading capability to the film, with clay particle content exceeding 18 wt %.