Research On Photochemical Degradation Of New Pesticide Phenazine-1-carboxamide In Aqueous Solution

Phenazine-1-carboxamide is an new type of antibiotic fungicide,which has strong inhibitory effect against a variety of pathogenic fungi of vegetables andn fruits.In order to evaluate the mobility,transformation and fate of phenazine-1-carboxamide in environmental media,photodegradation mechanism of phenazine-1-carboxamide in aqueous solutions were studied from June of 2015 to May of 2016 to provide the scientific guidelines of reasonalbe applications and environmental risk assessment.The main results were summarized as follows:?1?The initial concentration has an important influence on phenazine-1-carboxamide photolysis,the photolysis rate decreased with the increase of initial concentration.The UV photolysis half-lives of 2,5 and 10mg/kg were 14.174h,28.191h and 22.012h,respectively.?2?The pH value has an important influence on phenazine-1-carboxamide photolysis,phenazine-1-carboxamide photolyzed fastest in acidic solution and slowest in alkaline solution.?3?Ions have an important effect on the photolysis of phenazine-1-carboxamide.Fe³⁺?NH+4?NO-3 have photosensitive effect on it,Cu²⁺?NO-2 have photoquench effect on it.?4?Organicmatter hasan important effectonthephotolysisof phenazine-1-carboxamide,10mg/kg humic acid has inhibitory effect on the photolysis of it.?5?The light source has an important effect on the photolysis of phenazine-1-carboxamide,the UV photolysis rate is faster than the xenon lamp photolysisrateinwater,acetonitrile,methanolandhexane solution.phenazine-1-carboxamide UV photolysis is slower than the xenon lamp photolysis in acetone and ethyl acetate solution.?6?The water source has an important effect on the photolysis of phenazine-1-carboxamide,the photolysis rates in the increasing order were as follow:ultrapure water>bottled water>tap water>Xiangjiang water.?7?The proposed pathways of phenazine-1-carboxamide UV photolysis in methanole?hexane?acetone were:methanol solution produced CH₃O·under UV irradiation,occurring substitution reaction at 3,7 carbon and resulting in two degradation products A and B;hexane solution produce OH·under UV irradiation,occurring substitution reaction at 3 or 7 carbon and generating a product C or D;in the acetone solution of phenazine-1-carboxamide,two C-N of heterocyclic ring break firstly,then two C connected a OH·and a H·respectively,resulting in a product E.