The Study On The Synthesis,Characterization And Adsorption Properties Of Several Metal Organic Frameworks Composite Materials

The residue of persistent organic pollutants?POPs?in the environment such as some pesticides and pesticides is harmful,which is a direct or indirect threat on human health and the safety of the ecological environment.Because of the complexity of environmental samples matrix,at the same time,there are many interfering substance,which are easily affected by the environment,and the most of pollutants in environmental matrix is trace content.Therefore,it is necessary to develop some new,efficient,time-saving and easy to operate the sample pretreatment technologies to solve these problems,the choice of the adsorption medium is the key.Therefore,the development of adsorption medium?material?with high selectivity and enrichment capability becomes the research focus of sample pretreatment technology.New adsorption materials have the advantages of low density,large specific surface area,controllable pore size,modifiable surface of the material,excellent chemical and physical stability,such as metal organic frameworks polymer?MOFs?.In this thesis,a series of different structural characteristics of metal organic frameworks and its composites using metal Zinc and Cu as the center and H3 BTC as organic ligands were prepared,adsorption and extraction efficiency of pesticide and insecticide for environmental water samples were investigated in detailed.This paper is mainly composed of four chapters.In Chapter 1,the development history,classification,structure characteristics and the research and application of the metal organic framework and its composite materials are reviewed.At the same time,the purpose and significance of the study are presented.In Chapter 2,different metal organic frameworks Zn-BTC were synthesized by solvothermal method,direct addition method and diffusion method,respectively.In morphology,we used expander agents?cyclohexane?to make Zn-MOFs anisotropic growth and it generates various shapes Zn-BTC.The samples were characterized by thermogravimetry?TG?,fourier transform infrared spectroscopy?FT-IR?,scanning electron microscopy?SEM?and others.The stable and adsorption properties of Zn-BTC as adsorbent of dispersive solid phase extraction?DSPE?combined with HPLC were investigated.Remarkably,the Zn-BTC demonstrated significant adsorption properties for six pesticides removal.In Chapter 3,the metal organic framework and its composite were synthesized by the solvothermal method.A new magnetic nanoparticles?named as Fe₃O₄@SiO₂-GO-MOFs?was synthesized by covalent bonding of the GO nanosheets and silica-coated Fe₃O₄?Fe₃O₄@SiO₂?with core-shell structured,and then the GO surfaces were modified with Cu-MOFs.The nanocomposites combine both advantages of the large surface area of GO,and magnetic property of Fe₃O₄ without any limitations and drawbacks.The silica shells not only protect Fe₃O₄ particles against oxidation and agglomeration,but also serve as a platform to integrate the Fe₃O₄ particles and GO nanosheets through covalent bond.This integration can be carried out with easy modification of silica shells with amine groups and then chemical bonding of amines with carboxylic groups on the GO nanosheets.The Cu-MOFs modified GO provide more active sites for adsorption owing to the high porosity and tunability of MOFs.At last,the samples structures were characterized by SEM,FT-IR,XRD and N2 adsorption desorption transmission.The results showed that the stable structure with high specific surface area and porosity could be used as novel adsorption materials to be applied to the sample pretreatment.In Chapter 4,the synthesized metal organic frameworks Fe₃O₄@SiO₂-GO-MOFs and its composites were used as adsorbent for magnetic solid phase dispersion extraction?MSPE?for the adsorption of six insecticides in environmental water samples.At the same time,the factors such as adsorbent amount,extraction time,extraction temperature,oscillation rate and desorption time were optimized,and compared with the self-made metal organic frameworks and single-walled carbon nanotubes,the sensitivity and accuracy of the method were examined.The results show that the metal organic frameworks composite Fe₃O₄@SiO₂-GO-MOFs has excellent adsorption properties and is a novel adsorption material.