乙酰甲胺磷水解动力学研究

Hydrolysis Dynamics of Acephate in Aquatic Environment

采用气谱-质谱联用的分析方法,研究了乙酰甲胺磷在不同pH和温度条件下的水解动力学.结果表明,乙酰甲胺磷在酸性条件下比较稳定,不易水解,在碱性条件下水解速率较快,25℃时,乙酰甲胺磷在pH5.0,7.0,9.0水解速率常数分别为5.3×10-3,1.99×10-2,7.42×10-2 d-1,半衰期分别为130.8,34.83,9.34 d;50℃时,水解速率常数为1.012×10-1,2.04×10-1,7.542×10-1 d-1,半衰期为6.85,3.40,0.92 d.温度升高有利于乙酰甲胺磷的水解反应,pH5.0,7.0,9.0缓冲溶液中的水解活化能分别为94.38,74.47,74.19 kJ/mol;在酸性环境中,水解速率受温度影响更为显著.

This paper is an attempt to study Hydrolysis kinetics of acephate at various buffer solution in different temperature. The degradation rate was measured through GC-MS. The kinetics process of acephate can be described by the first-order reaction law. The results indicated that acephate was stably in acidic water, while the hydrolysis rate accelerated with the rising pH value. The higher temperature was helpful for the hydrolysis process. Under dark conditions at 25 ℃, the hydrolysis rate constants k of acephate in pH5.0, pH7.0, pH9.0 waters were 5.3×10^-3, 1.99×10^-2, 7.42×10^-2d^-1 and the corresponding half life were 130.8, 34.83,9.34 d. Under dark conditions at 50 ℃, the hydrolysis rate constants K of acephate in pH5.0, pH7,0, pH9.0 waters were 1.012×10^-1, 2.04×10^-1, 7.542×10^-1d^-1 and the corresponding half life were 6.85, 3.40, 0.92 d. The hydrolysis activation energy of acephate was the highest in acidic water, which led to the best the effect of temperature on hydrolysis in acid water.