A kinetic approach to the detoxification of organophosphorus based pesticide by alkylated hydroxamate ions in micellar system

The catalytic rate of paraoxon (i.e. O, O-diethyl- O-p-nitrophenyl phosphate) hydrolysis was measured kinetically with UV-visible spectrophotometric method using acetohydroxamate (AHA−) and decanohydroxamate ions (DHA−) as detoxifying agents. Toxicity reducing of paraoxon is devoted to the basis of nucleophilic reactivity of hydroxamate ions toward the electrophilic center of P=O bond of paraoxon in both aqueous and micellar mediums. The experimental results indicate that the DHA-micelle bind system exhibited relatively high (k2 ≈1.30-fold) and excellent catalytic function in paraoxon hydrolysis compared to the AHA-micelle system. The significant micellar interaction of DHA has been observed with cetyltrimethylammonium brome (CTAB) micelles and shown greater micellar catalysis (k2m/k2w) with the factor ≈ 839 than 240 for AHA, respectively. The pseudo-phase model (PPM) was employed in order to determine micellar second order rate constant and binding constant in this work. As a consequence, the effect of different types of alkanes on micellization behavior i.e. critical micelle concentration (CMC) of cationic surfactants, i.e. cetyltrimethylammonium ammonium bromide was investigated using Systronics direct reading conductivity meter at 300 K in aqueous system. The outcome of results shows that the micellization of surfactant decreases with influence of long-chain alkane compared to short-chain alkane.