Synthesis Of Zeolite Imidazole Frameworks And Its Application In The Analysis Of Organic Pollutants In Environmental Water Samples

Metal organic frameworks（MOF）is a novel functional nanometer material with controllable pore structure,large specific surface area,special metal center,good thermal and solvent stability.MOFs are composed of metal center and multi-chelated organic ligands,which is the main reason of the structural diversity and adjustable,zeolite imidazole ester framework（ZIF）is one of the most important categories.ZIF is a Zn metal ion as metal centers,with organic ester imidazole self-assembled to form a ligand connected zeolite framework materials.The thermal stability of ZIFs is superior to the MOF materials general,which is attributed to the zeolite-like framework structural of nitrogen heterocyclic rings.Magnetic zeolite imidazolate materials combines the advantage of magnetic separation of Fe₃O₄ and adsorptive capacity of ZIFs,which is widely used in catalysis,gas adsorption separation and adsorption removal of organic compounds.Solvent thermal synthesis is one of the most important methods of ZIF materials.This research work is carried out based on the performance of ZIF and magnetic adsorbent and easy separation of the background,the development of new polymer solid phase extraction material has wide applicability as the core,set up and actual test research of a novel magnetic solid phase extraction method,the main contents and conclusions of this thesis are as follows:（1）By comparing the co-precipitation method and hydrothermal synthesis method for preparation of Fe₃O₄ nanoparticles,the preparation of Fe₃O₄ was brown,good magnetic particles,irregular shape,size is not uniform,the nanoparticles were spherical,high specific surface area,and can control the synthesis time,material ratio,and temperature control of particle size,specific surface area.The magnetic core shell material Fe₃O₄@ZIF-8 was prepared by loading ZIF-8 on the outer surface of the magnetic core.The scanning electron microscopy,transmission electron microscopy and Fourier transform infrared spectroscopy were used to characterize the material.The results show that the synthesized zeolite imidazole ester material is coated on the surface of the magnetic core,forming a shell,forming a magnetic zeolite imidazole ester material.（2）Pesticide plays an important role in the agricultural production in China,a large number of pesticides has led to serious water pollution,so the monitoring of a class of pesticide residues in aquatic environment is particularly important.Using the magnetic material as magnetic zeolite imidazolate SPE sorbent,extracting four phenylurea herbicides in environmental water samples,combined with ultra performance liquid chromatography tandem mass spectrometry determination of analyte concentration,were optimized magnetic adsorbent dosage,adsorption temperature,eluent type,eluent dosage,extraction time,the analysis time,pH value and ionic strength and other factors,to achieve the best extraction of four kinds of phenylurea herbicides in water,and verify the linear relationship,the lower limit of quantification,detection limit and standard deviation,the method has low detection limit,low cost and low consumption of organic solvent,adding standard of detection the actual water samples,the recoveries were in the range of 78.8¹06.2%,RSD 1.3⁸.8%.（3）Microcystins produced in a large area of cyanobacteria seriously affect water quality,and it is particularly important to monitor the concentration of microcystins in water.Trace amounts of microcystins in water were extracted with magnetic zeolite imidazole ester as magnetic adsorbent.Magnetic zeolite imidazole ester material in a wide range of pH surface with positive charge,the surface of microcystin negatively charged molecules,due to positive and negative charge attraction,microcystins are easy to extract magnetic adsorbent.Experiments were optimized dosage,magnetic adsorbent pH value,extraction,elution agents,elution factors dosage,extraction time and ionic strength,to achieve the best extraction of two kinds of microcystins in the water,and verify the linear relationship,the lower limit of quantification,detection limit and standard deviation of the method.With a low detection limit,low cost.For the actual water sample spiked detection,the recovery range is 83.1¹07.8%,RSD is 1.2⁹.6%.