摘要
Abstract
The hydrolysis of 2,4-D butylate in the buffered solutions under the temperatures, and its photolysis in different organic solvents were studied in the laboratory. The results showed that hydrolysis and photolysis rate of 2,4-D butylate could be characterized by first-order kinetics equation. The hydrolytic rate of 2,4-D butylate in the solution of pH 5 and 7 was slow, but increased in basic solution. The half life was 23.5 d, 5.8 d and 10.7 min in the solutions of pH 5, 7 and 9 at 25 ℃, respectively. The hydrolytic rate of 2,4-D butylate increased with the increasing temperature. The half life was 21.5, 5.8 d and 3.9 d at 15, 25 ℃ and 35 ℃ in pH 7 solution, respectively,and the average temperature coefficient was 2.57. There were no obvious correlations between the activation energy and temperature, and the activation entropy showed a significantly negative correlation with the temperature. Activation entropy was negative, suggesting that hydrolysis of 2,4-D butylate in the aqueous solution was driven by its activation entropy. The hydrolytic products of 2,4-D butylate were identified as 2,4-dichlorophenoxyacetic acid and 2,4-dichlorophenol by GC-MS, suggesting that the degradation route of 2,4-D butylate was mainly via ester bonds and aryl ether bond cleavage. The photolytic rate of 2,4-D butylate in n-hexane was faster than in methanol, and it would not be degraded in acetone solvent. The photolytic rate became faster when decreasing concentration of 2,4-D butylate in n-hexane.关键词
2,4-D丁酯/水解/活化能/活化熵/光解Key words
2,4-D butylate/ hydrolysis/ activation energy/ activation entropy/ photolysis分类
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