Green Synthesis Of Covalent Organic Frameworks For Degradation Of Organic Pollutants

Covalent organic frameworks?COFs?as a new class of fascinating crystalline porous materials are composed of light elements,such as C,H,N,B and O,and connected by covalent bonds.Due to their well-defined pore geometry,high surface area,and tunable framework composition,COFs hold great promise in a variety of potential applications,including gas adsorption and separation,heterogeneous catalysis,opto-electronic and electrical energy storage devices,and several others.Over the past decade,COFs have been obtained by limited reversible chemical reactions,typically the formation of boroxine,boronate-ester,imine,imide,triazine,alkene and dioxin linkage.recently,Perepichka and co-workers reported a series of COFs that is obtained by the michael addition-elimination reaction,which further increased the reaction type of COFs.Furthermore,the classical synthesis of COFs so far is restricted to the solvothermal synthesis,which is implemented in sealed tubes with raising temperatures and pressures,and needs complicated operations and high energy expenditure.Green synthesis using mild reaction conditions and nontoxic precursors,as a reliable,sustainable and eco-friendly protocol,has attracted extensive attention for reducing destructive effects related to traditional methods in the laboratory and industry.We have exploited a fast,ambient temperature and pressure ionothermal synthesis of COFs;however,the high cost of ionic liquids hinders the application of this method for large-scale preparation of COFs.Therefore,the development of a simple,low cost and green synthetic strategy for COFs is still highly beneficial.Taking these considerations in mind,we herein report a mild,low cost and green process to prepare a number of microporous or mesoporous COFs by a?-ketoenamine based Michael addition–elimination reaction in aqueous systems under ambient conditions.This method not only solves the problem of high energy consumption and complex operation in COFs synthesis,but also the environmental pollution was reduced through water as solvent,which lays a foundation for the industrial production of COFs materials in the future.This work focuses on the method of green synthesis of covalent organic framework for degradation of organic Pollutants.This thesis mainly includes the following aspects:Part ?:Firstly,the reaction types of COFs are introduced in detail,such as boroxine,boronate-ester,imine,imide,triazine,alkene and so on.Then the advantages and disadvantages of common synthetic COFs methods are analyzed.Finally,the principle and prospect of water purification by Fenton method are introduced.The significance of using COFs materials in Fenton reaction is analyzed.Part ?:Firstly,two new organic monomers,1,3,5-tris?3-dimethylamino-1-oxoprop-2-en-yl?benzene?TDOEB?and 1,3,5-tricarboxylicacid-tris?4-amino-phenyl-amide?benzene?TCTAB?,were synthesized.Using Michael addition-eliminate,the optimum conditions of green synthetic COFs were explored in detail by using the two organic monomers materials.Then,a series of new COFs materials were successfully synthesized by using TDOEB with three amino monomers in water,at room temperature and atmospheric pressure.Finally,the PXRD,SEM,FTIR,NMR,stability and N₂ adsorption-desorption of this material are characterized in detail.Part ?:Firstly,a model molecular TPOEB was synthesized by michael addition-elimination reaction.The Fenton reaction catalyst was prepared by coordinating TPOEB and JUC-521 with Fe²⁺.Finally,the catalytic capacity of these two catalysts was tested in Fenton reaction.The advantages of COFs materials in Fenton reaction were analyzed.Part ?:Summarizes the content of this paper and looks forward to the development prospects of COFs in the future.