Study On The Degradation Mechanism And Ecotoxicity Of Three Typical PPCPs In Wate

Phthalate esters,guaiacol and synthetic musk compounds are typical PCCPs.These three types of PCCPs are rich in variety.They are widely used in chemical industry,food processing industry and daily chemical industry.Phthalate esters are often used as plasticizers in the production process of PVC materials.They are also the main additives in plastic toys,detergents,lubricants,soaps,nail polish and other daily necessities.Guaiacol compounds are crucial raw materials in the pharmaceutical research and development,food additives and spice synthesis.Synthetic musk compounds are the most common additives in personal care products,which usually used in the production of cigarettes,baits,feeds,perfumes and facial essences.Except natural sources,anthropogenic emissions have become the main sources of the above three types of typical PCCPs in water.They can react with common oxidants（such as O₂,NO and HNO₂）in the water environment to generate degradation products.In order to further study the oxidative degradation processes of above three types of typical PCCPs in water.This work respectively investigated the degradation processes of diethyl phthalate（phthalate ester compounds）,4-vinyl guaiacol（guaiacol compounds）and tonalide（synthetic musk compounds）in aqueous solution by using quantum chemical calculation method.In this paper,detailed reaction mechanism and kinetic data were obtained,and the ecotoxicity of diethyl phthalate,4-vinyl guaiacol,tonalide and their degradation products was evaluated.The conclusions obtained are as follows:1.The degradation mechanism,kinetics and ecotoxicity assessment of diethyl phthalate induced by HO?/SO₄^?-in aquatic environmentThe chemical degradation processes of diethyl phthalate initiated by HO?/SO₄^?-in water environment at M062X/6-31+G（d,p）level were invesgatied theoretically.The degradation processes of diethyl phthalate include radical addition,H-abstraction processes and the single electron transfer reaction.The intermediates generated from its primary reactions can continue to react with oxidants such as O₂,NO and HNO₂.Thermodynamic and kinetic calculation results show that HO?has higher reactivity toward diethyl phthalate compared with SO₄^?-.However,H-abstraction reactions occurring in aliphatic side chains initiated by HO?are more energetically favorable.At298 K,the total reaction rate constants of diethyl phthalate induced by HO?and SO₄^?-are 3.34×10⁹ and 1.05×10⁸ M^-1 s^-1,which is consistent with experimental values.In addition,ECOSAR,T.E.S.T and EPI Suite are used for the ecotoxicity assessment of the reactant and products.The results show that diethyl phthalate and its ten products will not accumulate in aquatic organisms.However,except for（Z）-ethyl-2,5-dioxolan-3-enoic acid（P2）,most of the products are developmentally toxic.At the same time,（Z）-ethyl-2,5-dioxolan-3-enoic acid is acutely toxic to fish;and phthalic acid（P7）is mutagenic positive.We should pay more attention to them in future.In this chapter,the acute toxicity of diethyl phthalate to zebrafish was studied.In the course of the experiment,the poisoning symptoms of zebrafish were shown as action retardation,reaction retardation and death.The median lethal concentration(LC₅₀)of diethyl phthalate for zebrafish at 96h calculated by IBM SPSS Statistics was 12.36 mg L^-1,which match the predicted value obtained by ECOSAR well.2.The degradation mechanism,kinetics and ecotoxicity assessment of 4-vinyl guaiacol induced by HO?/SO₄^?-in aquatic environmentThe reactions between 4-vinyl guaiacol and HO?/SO₄^?-in aqueous environment at M062X/6-31+G（d,p）level were invesgatied theoretically.4-vinyl guaiacol can be degraded by radical addition,H-abstraction and single electron transfer reactions.The intermediates generated by its primary reactions can continue to react with oxidants such as O₂,NO and HNO₂.The results of thermodynamic and kinetic calculations show that addition processes are the main reactions between two free radicals and 4-vinyl guaiacol,two HO?addition reactions on C1 and C6 atoms are the most energetically favorable reaction paths.At 298 K,the total reaction rate constants for oxidative degradation reactions of 4-vinyl guaiacol initiated by HO?and SO₄^?-are 2.36×10¹¹and4.35×10¹⁰ M^-1 s^-1,respectively.Furthermore,the ecotoxicity assessment of ECOSAR,T.E.S.T and EPI Suite on the reactant and products show that the 4-hydroxy-3-methoxybenzaldehyde（P1）,2-hydroxyacetaldehyde（P2）and（2E,4E）-methyl-3-formyl-5-hydroxyphenyl-2,4-dienoate（P5）have potential impacts on aquatic environment.3.The degradation mechanism,kinetics and ecotoxicity assessment of tonalide induced by HO?/SO₄^?-in aquatic environmentThe oxidative degradation reactions of HO?/SO₄^?-with tonalide in water environment at M062X/6-31+G（d,p）level were invesgatied theoretically.Three model of tonalide degradation processes are:radical addition,H-abstraction and single electron transfer reactions.The intermediates generated by the primary reactions can continue to react with oxidants such as O₂,NO and HNO₂.According to the themodyn amic and kinetic calculation results,H-abstraction processes of C atoms in methyl and methoxy induced by HO?are the main degradation paths of tonalide,and the H-abstraction process on C9 atom is the most energetically favorable reaction path.At298 K,the total reaction rate constants of tonalide+HO?/SO₄^?-reactions are 8.20×10⁹and 2.12×10⁸ M^-1 s^-1,respectively.The ecotoxicity assessment of the reactant and products show that the acute and chronic toxicity of tonalide is high.All reactants,products and important intermediates are developmental toxic.And the 3-acetyl-5,5,7,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalene-2-carbonaldehyde（P3）,2-（3,5,5,6,8,8-hexamethyl-5,6,7,8-tetrahydronaphthalene-2-yl）-2-oxoacetaldehyde（P5）and 1-（3,5,5,6,8,8-hexamethyl-5,6,7,8-tetrahydronaphthalene-2-yl）-2-hydroxyethanone（P6）will accumulate in aquatic organisms,which need more attention for their impacts on water.