Myricetin Sensitized Photolysis Of Chlorothalonil In Water Solution

Photochemical degradation is one of the important behaviors of pesticides in the environment,which is of great significance for scientific evaluation of its potential environmental impact.The main metabolite of chlorothalonil in water environment was 4-hydroxychlorothalonil,and its toxicity was much higher than that of its parent.In order to degrade chlorothalonil in water environment quickly,safely and effectively and change its degradation pathway,myricetin was selected to study the photosensitive degradation of chlorothalonil in pure water and three kinds of natural water.The experimental results are summarized as follows:1.The photodegradation of chlorothalonil by myricetin under natural light or high pressure mercury lamp was increased by 8.9 and 7.4 times respectively,and myricetin significantly promoted the photosensitive degradation of chlorothalonil solution under light conditions;Chlorothalonil degradation rate was different under different light sources:high pressure mercury lamp>sunlight;And within the set concentration range,with the increase of myricetin concentration,the photodegradation reaction rate and photosensitization efficiency of chlorothalonil were gradually improved under natural light.The photodegradation rate and photosensitization efficiency of chlorothalonil increased first and then decreased under high pressure mercury lamp due to saturation effect.2.Under the irradiation of natural light or high-pressure mercury lamp,when myricetin was added into the aqueous solution of chlorothylamine,the content of chloride ion was significantly increased,indicating that this reaction was a dechlorination reaction;After the addition of myricetin,the degradation pathway of chlorothalonil in pure water was as follows:Chlorothalonil→2,4,5-trichloro-1,3-dicyanobenzene→2,5-dichloro-1,3-dicyanobenzene.However,myricetin could not degrade 5-chloro-1,3-dicyanobenzene,and its dechlorination reaction was not thorough enough.3.Myricetin could reduce the conversion rate of chlorothalonil into a highly toxic metabolite in aqueous solution,and the conversion rate of chlorothalonil showed a downward trend with the increase of myricetin concentration,and myricetin had no hydrolysis effect on chlorothalonil.4.Under the irradiation of natural light or high-pressure mercury lamp,when the molar ratio of chlorothalonil to myricetin in natural water was 1:10.0,the half-life of chlorothalonil was as follows:pure water>,rice field water≈pond water>,field gulch water.The root exudates of plants in Tianguo water produce phenolic substances and promote the photosensitive degradation of chlorothalonil by myricetin.Therefore,compared with the three kinds of natural water under the two light conditions,myricetin has the strongest degradation effect on chlorothalonil in Tianguo water.Myricetin in natural light or high pressure mercury lamp light conditions,the difference of chlorothalonil in natural water photosensitive effect is not obvious,natural water than pure water has the substance to inhibit the photosensitive effect of chlorothalonil.The enhancement of photodissociation of chlorothalonil by myricetin is of great significance for controlling the toxicity and pollution remediation of chlorothalonil in water bodies by myricetin,and has potential reference value for predicting the degradation of chlorothalonil in different plants.