Kinetics of alkaline and peroxide‐catalyzed hydrolysis of fenitrothion

Abstract

Alkaline hydrolysis of fenitrothion (F), at 26°C, over the pH range 9.5–14, was described by ‐d ln[F]/dt = 0.17 [^‐OH] + 6.4 x 10⁴ [HO₁ ^‐]. The peroxide concentration equalled [total peroxide] [^‐OH], provided that the hydroxide concentration was taken as 0.0044 M for all pH values in excess of 11.8. Energies of activation, measured over the range ll‐30°C, were 16.3 kcal mole^‐1, for alkaline hydrolysis, and 7.8 kcal mole^‐1, for peroxide‐catalyzed hydrolysis.

Appropriate regimes for decontamination of fenitrothion wastes can be calculated from the above data. Two regimes that are relatively safe and inexpensive are decontamination in a saturated aqueous solution of calcium hydroxide and decontamination in a solution of “1% w/v”; sodium carbonate plus 1–2 x 10^‐4 M total peroxide. The latter method is especially appropriate for cold temperatures, because of the low energy of activation of peroxide‐catalyzed hydrolysis.

Key words:

• Fenitrothion
• Alkaline Peroxide
• Pesticide Decontamination
• Kinetics