Applications Of Covalent Organic Framework Materials Coated Capillary In CEC Separation Of Organic Pollutants With Small Molecule

Capillary electrochromatography(CEC)is a chromatographic separation technology that uses high voltage direct current electric field as the driving force to separate analytes through the differences in fluidity and distribution behavior between components in a sample.It combines the good selectivity of high performance liquid chromatography with the high separation efficiency of capillary electrophoresis.Because the inner surface of the capillary is easy to be modified,many materials can be used as stationary phases in capillary electrochromatography,such as graphene,dopamine,metal organic frameworks(MOFs),and covalent organic frameworks(COFs),et al.Among them,COFs have the advantages of large specific surface area,high porosity,and easy functionalization,which attract lots of analytical chemists.Although COFs materials have been used in CEC in recent years,COFs connected by hydrazone bonds have not been used in CEC stationary phases yet.The hydrazone bond-linked COFs are easy to prepare and can be modified,And the ordered hydrazone bonds in the COFs can provide more hydrogen bond interaction sites for the analytes.Therefore,COFs connected by hydrazone bond can be used as an excellent CEC separation coating material.Based on the above advantages of the hydrazone bonded COFs,we have carried out the following innovative research work:(1)TP-DHTH COFs material was synthesized by solvothermal method,and its stability was studied.Then,TP-DHTH COFs coated capillary was prepared and applied to separate six estrogens.(2)TFPB-DHz DS COFs coated capillary column was prepared by a simple in-situ method at room temperature and applied to the separation of polycyclic aromatic hydrocarbons(PAHs).The influence of the coating concentration on the separation efficiency was investigated,and the method was applied to detection polycyclic aromatic hydrocarbons in water and soil samples.(3)Three COFs(COF-LZU1,COF-42 and COF-LZU8)with different connection types and side chains were used as CEC coating materials and applied to separate two groups of phthalates(PAEs).Then the separation mechanism was explored in detail.This dissertation consists of five chapters:Chapter 1: The different connection methods of COFs,the common synthesis methods of COFs and their applications in separation were introduced.Chapter 2: TP-DHTH COFs was successfully synthesized by solvothermal method.The material has good chemical stability,and can maintain its crystal structure in commonly used organic solvents,water,acid and base solutions.Subsequently,the TPDHTH COFs coated capillary was successfully prepared and used for the separation of six estrogens.The results showed that the coated capillary has high separation efficiency and good reproducibility and stability.Chapter 3: Based on the solvothermal synthesis method,we have developed a more convenient and feasible method for the synthesis of TFPB-DHz DS materials.Then,the TFPB-DHz DS COFs coated capillary was prepared by in-situ method at room temperature.By optimizing the coating concentration and CEC separation conditions,two groups of PAHs achieved baseline separation.A new method for PAHs separation has been established and can be used to determine PAHs in actual samples.And this method has been successfully used to detect PAHs in water and soil samples.Chapter 4: In order to investigate the differences in the separation ability of COFs coating materials with different structures,we synthesized three COFs with the same structural unit(1,3,5-Triformylbenzene),but the connection bond and side chain length are different.The three COFs coated capillaries were used to separate eight PAEs to evaluate the differences in separation efficiency of three COFs coatings with different structures on CEC.Based on the host-guest interaction,the relationship between the structure of COFs coating material and its separation ability was discussed.Experimental results together with theoretical calculations were utilized to explore the relationship between the COFs structure and their separation abilities based on the hostguest interaction.Chapter 5: Conclusion and prospects.