Decomposition of Organophosphorus Pesticides by Homoiouic Clays from Some Soils of Eastern Himalayan Regions

The decomposition of some organophosphorus pesticides [O-alkyl O, O-diparanitrophenyl phosphorothionates) by homoionic clays (Na⁺, CM²⁴⁺, Al³⁺) extracted from soils of eastern Himalayan region was studied at room temperature (around 25°C). In all cases, the catalytic decomposition of the pesticides gaveparanitro-phenol (λ max at pH 7 = 318 mn). Very goodpseudo first order kinetics was obtained indicating that the decomposition occurred essentially by P — O (aryl) bor,d cleavage. The rate of decomposition at pH 7 increased in the order, Na-clay >Cu-clay >Al-clay.