Photolysis and hydrolysis of 3,5-dichloroaniline in water

3,5-Dichloroaniline (3,5-DCA) is the main metabolite of dicarboximides fungicides (DCFs) in the environment and plants, and it is more toxic and persistent than the parent compounds. In this paper, the photolysis and hydrolysis of 3,5-DCA was studied in laboratory by using gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). The results showed that at the initial concentration of 5 mg/L, the photolysis half-lives of 3,5-DCA were 49.5 min and 11.6 min, respectively, under xenon lamp and UV lamp, and were 9.9 min, 168 min and 10.7 min under neutral, acidic and alkaline conditions. The half-lives were 4.10 h, 2.69 h and 0.58 h in methanol, acetonitrile and n-hexane, respectively. Further study found that the photolysis product of 3,5-DCA in n-hexane is mono-dechlorination product. The hydrolysis half-lives of 3,5-DCA at the initial concentration of 5 mg/L were 40.8 days in neutral, 77.0 days in acid and 86.6 days in alkaline solutions. Different concentrations of surfactant sodium dodecyl sulfonate (SDS) and cetyl trimethyl ammonium bromide (CTAB) solution inhibited the hydrolysis of 3,5-DCA, and the inhibition effect of CTAB was stronger than that of SDS. The results are helpful to understand the environmental fate of DCFs more comprehensively and provide data support for their rational use and environmental safety evaluation.