Preparation Of New Covalent Organic Framework Materials And Their Application In The Separation And Analysis Of Organic Pollutants

Covalent organic frameworks（COFs）is a new type of porous crystalline organic polymer with low density,large specific surface area,good stability and high porosity.COFs have been widely applied to gas storage,catalysis,sensing,and separation fields.COFs have also been used as excellent sorbents for sample pretreatment and chromatographic separation.However,the existing COFs usually are irregular submicron particles,which can lead to ultrahigh column pressure when used as the packing materials of on-line solid-phase extraction（SPE）.Therefore,its application in on-line SPE is greatly limited.In this dissertation,a preparation strategy for large-size COF microspheres was developed for the first time,and then an on-line SPE technique was constructed using the large-size COF microspheres as sorbents,which can address the problem of the ultrahigh column pressure.Furthermore,the new on-line SPE technique was applied successfully to the detection of bisphenol F coupled with high-performance liquid chromatography（HPLC）.Additionally,preparation of COF-based capillary monolithic column can also solve the above problem due to the good permeability of monolithic column.Therefore,an in-situ preparation method for COF-based capillary monolithic column was developed,and its application to the capillary electrochromatographic separation was investigated preliminarily.The research contents is listed in detail as follows:In the first part,tetrakis（4-aminophenyl）methane（TAM）monomer was synthesized first according to a literature using triphenylchloromethane as raw material.Then,the amorphous COF-320 large-size microspheres were prepared via emulsion polymerization at room temperature using 1-butyl-3-methylimidazolium bis[（trifluoromethyl）sulfonyl]imide（[BMIm][NTf₂]）as catalyst.Then the amorphous COF-320 microspheres are repaired under certain conditions to obtain a spherical COF with crystal structure.The structure and component of COF-320 were characterized by infrared spectroscopy（FT-IR）,scanning electron microscopy（SEM）,nitrogen adsorption-desorption,thermogravimetry analysis（TGA）,elemental analysis and X-ray diffraction（XRD）.The synthesis conditions for spherical amorphous COF-320 have been optimized,and the adsorption performance of crystal COF-320 on bisphenol F（BPF）has been studied.The thermodynamic adsorption test showed that COF-320 had good adsorption ability for BPF with the maximum adsorption capacity of125mg/g.The kinetic adsorption test showed that the adsorption of BPF on COF-320 reached equilibrium within 80 min.In addition,the on-line SPE property of crystal COF-320 was investigated.Results indicated that the COF-320 microspheres presented good on-line SPE ability.The particle size is 30～60μm,which is suitable for on-line SPE.The on-line SPE column（10mm×4.6mm）showed good permeability with the column pressure of only 3 bar when the flow rate of mobile phase was 1 m L/min.Moreover,when used for 20 times,the morphology of crystal COF spheres showed no obvious change,indicating their good mechanical strength.When the on-line SPE was coupled with HPLC,the recoveries of BPF in water samples with different concentrations（0.05μg/m L,0.1μg/m L,0.2μg/m L）were all higher than 95%,demonstrating that the accuracy of the new analytical method is satisfactory.In the second part,a COF-based capillary monolithic column was prepared in situ via a one-stepstrategyusingtris（4-aminobiphenyl）benzene（TABPB）and2,5-divinylterephthalaldehyde（DVA）as COF monomer,dimethyl sulfoxide as solvent,and ionic liquid as catalyst in the presence of crosslinker（EDMA）,initiator（AIBN）and porogen.It was characterized by FT-IR,SEM,nitrogen adsorption-desorption,TGA,XRD.The effect of the EDMA amount on the column permeability.Results showed that the increase of the EDMA amount decreased the permeability of the monolithic column.When more than 500μL of EDMA was used,the obtained capillary monolithic column was completely blocked.In this work,a COF-based capillary monolithic column was synthesized in situ via a one-step method,which can address the problem that the traditional preparation procedure for COF-based capillary monolithic column was tedious.The new strategy greatly simplified the preparation procedure for COF-based capillary monolithic column.