The hydrolytic and photolytic properties of 2,4-D isooctyl ester

In order to clarify the environmental behavior of 2,4-D isooctyl ester, the hydrolytic properties of 2,4-D isooctyl ester under different temperatures, pH values, types of water and initial concentrations, and its photolytic properties under different pH values, types of water, light sources and initial concentration were studied by the indoor simulation test method. The results showed that the hydrolysis half-lives of 2,4-D isooctyl ester with initial concentration of 5 mg/L were 346.6, 231.0 and 173.3 h at 15, 25 and 35 ℃, respectively, under neutral (pH 7) conditions. The hydrolysis half-lives of 2,4-D isooctyl ester in buffer solutions with pH values of 4, 7 and 9 were 77.0, 231.0 and 138.6 h, respectively, at 25 ℃. The hydrolysis rates of 2,4-D isooctyl ester in paddy water, tap water and river water were higher than that in the distilled water, the half-lives were 23.1, 25.7, 40.8 and 63.0 h, respectively. The hydrolysis half-lives of 2,4-D isooctyl ester with the initial concentration of 1, 3 and 5 mg/L in buffer solution with pH value of 7 were 231.0, 173.3 and 138.6 h, respectively. Under the irradiation of 300 W mercury lamp, the photolysis rates of 2,4-D isooctyl ester under the acidic condition was higher than that under the neutral and alkaline conditions, the half-lives were 49.5, 77.0 and 138.6 h, respectively. The photolysis rates of 2,4-D isooctyl ester in river water and paddy water were higher than that in tap water and distilled water, the half-lives were 6.7, 7.6, 43.3 and 46.2 h, respectively. The order of photolysis rates of 2,4-D isooctyl ester under different light sources were 500 W mercury lamp > 300 W mercury lamp > 500 W xenon lamp. The photolysis half-lives of 2,4-D isooctyl ester with initial concentration of 1, 3 and 5 mg/L in buffer solution with pH value of 7 were 63.0, 43.3 and 40.8 h, respectively. The main product of the hydrolysis and photolysis of 2,4-D isooctyl ester is 2,4-D. The main degradation mechanism is the hydrolysis of esters. The results can provide references for the rational use and environmental risk assessment of 2,4-D isooctyl ester.