Study On The Photodegradation Of CN-1 In An Aqueous Solution

Polychlorinated naphthalenes?PCNs?are fused bicyclic aromatic compounds with a naphthyl structure with 1 to 8 chlorine atoms attached to the naphthalene ring and theoretically 75 homologues.Monochloronaphthalene has two isomers:1-chloronaphthalene?CN-1?,2-chloronaphthalene?CN-2?.They are mainly used as raw materials for organic synthesis.Current research has found that PCNs are toxic,and environmental sustainability and bioaccumulation are due to the persistence of PCNs,dioxin-like toxicity,and similar properties to PCBs,which are included in the Stockholm Convention POPs..Therefore,polychlorinated naphthalene is receiving more and more attention.Research on polychlorinated naphthalenes will become a hot topic in the field of environmental science.In this experiment,the photoconversion process and mechanism of monochloronaphthalene in aqueous solution were studied using a medium-pressure mercury lamp with a light intensity of 14 W m^-2.The influencing factors affecting the photodegradation of CN-1 were investigated?substrate concentration,pH,Hydroxyl radicals?·OH?,singlet oxygen,salts?,and comparison of the influencing factors of CN-2 photolysis,analysis of photolysis products of CN-1 in aqueous solution,and inferring the conversion of CN-1 light Changes in the concentration of hydroxyl radicals during the process and the following conclusions.In aqueous solution,the photo-conversion of CN-1 and CN-2 can occur,and the photo-inversion processes of CN-1 and CN-2 all conform to the first-order kinetic formula.The acidic condition promotes the photolysis of CN-1.Alkaline conditions have little effect on the photolysis of CN-1.Acid conditions promote the photolysis of CN-2,but the effect is small,and the effect on the CN-2 Photolysis has almost no effect;SO₄^2-has little effect on the photolysis of CN-1;NO₃^-promotes the photolytic conversion of CN-1;SO₃^2-promotes the photolytic conversion of CN-1;in systems containing SO₃^2-Adding different amounts of tert-butanol and ethanol will inhibit the photolysis of CN-1;isopropanol?IPA?will inhibit the photolysis of CN-1;at the same time,IPA will also inhibit the photolysis of CN-2.However,the inhibitory rate was lower and the inhibitory effect was weaker;the hydrogen peroxide injection accelerated the photolysis of CN-1;when the molar concentration of hydrogen peroxide in the system was 10?mol L^-1,the photolysis reaction of CN-2 was inhibited.When the molar concentration of hydrogen peroxide in the system is 100?mol L^-1,the photolysis reaction of CN-2 is accelerated,and the OH and CN are measured by the competition experiments of CN-1 and Rhdamine B?RhB?.The reaction rate of-1is 9*10⁹ mol L^-1s^-1,which shows that the contribution of OH in the photolysis and conversion of CN-1 is not large;it is measured by the competitive reaction between CN-2 and RhB.The reaction rate between OH and CN-1 was 1.9*10¹⁰ L mol^-1 s^-1;sterol inhibited the photolysis of CN-1;the concentration of chloride ion in the photolysis process of CN-1 showed a decreasing trend overall;CN-1 The photolysis products in aqueous solution are mainly 1-naphthol and naphthalene.The conclusion of this paper can supplement people's understanding of the photochemical transformation behavior of monochloronaphthalene,and can also provide a theoretical basis for the use of ultraviolet light to degrade monochloronaphthalene in water.