Abstract
| - The hydrolysis of triazophos was studied in buffered solutions in the range of pH 4−10 and in sodiumhydroxide solutions with pH values up to 12. The results showed that the degradation of triazophosin the above solutions followed simple pseudo-first-order kinetics. At 35 °C, the rate constants inbuffered solutions ranged from 0.0222 d-1 at pH 4 to 0.5357 d-1 at pH 10, and increased to 0.6251h-1 in 0.01 mol/L sodium hydroxide solution. The results also indicated that the base-catalysis wasmore important than acid-catalysis in the hydrolysis of triazophos. On the basis of the Arrhenius plot,the calculated activation energy (Ea) and the frequency factor (A) for the hydrolysis of triazophos inbuffered solution of pH 10 were 78.6 kJ/mol and 1.13 × 1013 d-1, respectively. Hydrolytic productsof triazophos in buffered solutions of pH 4 and 10, as well as in sodium hydroxide solution of pH 11,were identified as their corresponding trimethylsilyl derivatives with a gas chromatography−massspectrometer (GC−MS). The possible hydrolytic pathways of triazophos were also proposed. Keywords: Triazophos; Hostathion; hydrolysis; degradation; kinetics
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