| Perfluorinated compounds are a kind of anthropogenic organofluorine chemicals,which are harmful to animals and human body.The wide distribution and low contents of the substances in the environment and the complexity of environmental samples will also affect the analysis and detection,so sample pretreatment become a necessary method to analyze of PFCs.The selection of adsorption materials is particularly critical in the pretreatment technology.Therefore,it is very important to develop a class of materials that can be easily selectively enriched from complex systems and to establish a detection method for trace PFCS in environmental samples.In the work,the method for the rapidly preparation of fluorine porous organic polymers was established,based on fluorine-affinity,mesoporous environment,hydrogen bonding,and electrostatic interaction,combined with ultra high performance liquid chromatography coupled to mass spectrometry(UPLC-MS)to adsorpt PFCs in environmental water samples.The work includes the following three parts:Chapter 1:IntroductionThis chapter mainly introduces the contents of four aspects.several sample pretreatment methods are described.The classifications of porous organic polymers are discussed.The applications of porous organic polymers are also described in analytical chemistry.In the end,the work briefly expounded the thesis proposal basis and main content.Chapter 2:Preparation of spherical fluorinated covalent organic framework with controllable size at room temperature for the enrichment and detection of perfluorinated compounds in environmental water samplesFluoryl covalent organic framework materials(F-COFs)can be rapidly synthesized from 1,3,5-trivalent(4-aminophenyl)benzene and tetrafluoroterephthaldehyde using acetonitrile as solvent and acetic acid as catalyst with schiff-base at room temperature.F-COFs was synthesized by adding catalysts of different volumes,and the size range of the F-COFs was nm-?m.The materials were characterized by Scanning electron microscopy,Transmission electron microscopy,Powder x-ray diffractometer,Thermogravimetric analysis,Fourier transform infrared spectrum,Multifunctional imaging electron spectroscopy,Video optical contact angle,and Zeta potential.The characterization results showed that the morphology of the material was uniformly dispersed,the thermal stability was good,and the surface contact angle of the material reached 134.2°.F-COFs with a particle size of 1 ?m were selected as disperse solid phase extraction(DSPE)adsorbent,combined with ultra-performance liquid chromatography-mass spectrometry(UPLC-MS),to establish a method for the determination of PFCs in environmental water samples.The method was measured at 10-100 ng L-1(LODs(S/N=3)and LOQs(S/N=10)were in the range of 0.13-0.44 ng L-1 and 0.43-1.47 ng L=1,respectively,and the enrichment ratio reached 203.The new method has been successfully applied to the analysis of PFCS in real water samples with recoveries of 76.9-116.5%and relative standard deviations(RSDs)of 2.7-7.3%.It is proved that the combined analysis method of F-COFs as sample pretreatment material and UPLC-MS can be used for enrichment and detection of trace PFCs in environmental water samples.Chapter 3:Preparation of fluorinated covalent organic polymers at room temperature for removal and detection of perfluorinated compoundsCovalent organic polymer(COP),a class of COFs analog was designed and synthesized with high thermodynamic stability.By using 4,4-diamino-p-tribenzene and tetrafluoroterephthaldehyde as ligands through the schiff base reaction and acetic acid as the catalyst at room temperature.The results showed that with the polarity of the reaction solvent increased,the morphology of the material gradually changed from spherical to flower-shaped,and the size also gradually increased.Finally,the flower-shaped F-COPS with acetonitrile as the solvent was selected for subsequent characterization and adsorption separation experiments.Infrared characterization revealed that there were C=N stretching vibration and C-F stretching vibration,indicating the imine bond successful synthesis and the retention of fluorine groups.By BET calculation,the specific surface area of the material was 78.17m2 g-1,the pore volume was 0.297 cm3 g-1,and the average pore diameter was 18.49 nm.The elements results showed that the fluoride content reached about 19%and the surface water contact Angle of the material reached 137.1°.The surface is positive when pH<5.0,and decreases gradually with the increase of pH.In adsorption experiments,several main factors affecting the adsorption efficiency was investigated.The effects of adsorption kinetics and adsorption isothermal model simulation results were investigated.The results showed that the adsorption process conforms to the second-order kinetics,indicating that the whole process was not only affected by the material transport process,but also involved in the chemical adsorption.There were two binding sites on the surface of the adsorbent,which further proved the influence of the fluorophile effect.The Langmuir equation was used to calculate the saturated adsorption amount,the saturated adsorption capacity can reach 323-667 mg g-1,and the adsorption capacity gradually increases with the increase of carbon chain.The material is used to simulate the adsorption and removal of PFCs in wastewater,and the removal rate reaches 92.3-100.0%.After treatment,The residual level of PFCs is close to or even lower than the U.S.Environmental Protection Agency's drinking water health warning(70 ng/L).Proved F-COPs can be applied to the treatment of fluorine-containing wastewater.Using this material as DSPE adsorbent,a DSPE-UPLC-MS analysis method for detecting PFCs in environmental water samples was established.This method had the advantages of wide linear range(10-200 ng L-1)and high sensitivity(LODs were 0.05-0.13 ng L-1,LOQs were 0.17-0.43 ng L-1).And the newly established method was applied to the recovery detection of the PFCs in the actual water sample,the recovery rates were 95.6-116.4%,and the relative standard deviations were between 2.5-9.5%. |
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