Zero valent Iron 및 manganese oxide에 의한 살균제 chlorothalonil의 탈염소화
Dechlorination of fungicide chlorothalonil by zero valent iron and manganese oxide
농약 살균제 탈염소화;
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The arylnitrile fungicide, chlorothalonil which has low toxicity for mammal and relatively a short environmental half-life(5-36 day) was known to be highly toxic to fish as it contains 4 chlorines. The more stable degradative mechanism of chlorothalonil is required because 4-hydroxy chlorothalonil, a major degradative product of chlorothalonil is more toxic, persistent and mobilile than its parent molecule. In this research, transformation of chlorothalonil was investigated by treatments of abiotic reagents including zero valent iron(ZVI), pyrolusite and birnessite in the aqueous system. All reagents used in this research represented much higher degradative effects in low pH and degradation rate was proportioned to the added amount of treated reagent. The half-lives of chlorothalonil by using ZVI, pyrolusite and birnessite in citrate-phosphate buffer(pH 5.0) solution corresponded to 4.7, 13.46 and 21.38 hr respectively. In order to examine the dechlorination of chlorothalonil, the amount of chloride ion produced during reaction with abiotic reagents was analysed using ion chromatograph(IC). The each numbers of chloride ion produced during degradation of chlorothalonil by treatment of ZVI, pyrolusite and birnessite were 2.85, 1.12 and 1.09, respectively. GC-MS was used to confirm molecular weights of degradative products of chlorothalonil by abiotic reagents. Identified products of chlorothalonil by pyrolusite and birnessite were confirmed as trichloro-1,3-dicyanobenzene and dichloro-1,3-dicyanobenzene which were dechlorinated one or two chlorine ions from parent chlorothalonil. Degradative products of chlorothalonil by ZVI were identified not only as those by pyrolusite and birnessite but as further reduced chloro-1,3-dicyanobenzene and chlorocyanobenzene.