Synthesis And Functionalizing Of New Porous Materials And Their Usage In Separation

New porous crystalline materials,including metal organic framework（MOF）and covalent organic framework（COF）,have a wide range of applications in the fields of chemistry,materials science and physics due to their diverse backbone structure and pore structure,large surface area and chemical and thermal stability.The method of introducing functional groups on MOF or COF are pre-synthesis method and post-synthetic modification（PSM）method.PSM means MOF or COF is first synthesized and then functional group is reacted with organic molecules.The method has several advantages:it is easy to operate,will not damage MOF or COF structures,and can even successfully synthesize MOF and COF structures which cannot be synthesized by pre-synthesis method.Therefore,this method has received great attention from scientists,but more MOF and COF synthesized by PSM are still need to be developed.In this thesis,a series of studies on the synthesis and PSM of MOF and COF and their applications in separation field are carried out.The main research results are as follows:1.A UiO-66 series MOF named UiO-66-NH₂ has good potential for PSM due to it has amino group.The imidazole molecule is rich in nitrogen atoms so it has good adsorption to CO₂,but has no effect on methane.Therefore,in order to obtain a higher CO₂/CH₄ separation factor,we grafted imidazole-2-carbaldehyde to UiO-66-NH₂nanoparticles by using the Schiff base condensation reaction to obtain a novel MOF:UiO-66-NH₂@ICA.The adsorption test of CO₂ and CH₄ at 298K proved that UiO-66-NH₂@ICA has a stronger adsorption effect on CO₂ than pristine UiO-66-NH₂.Mixed matrix membrane（MMM）is easy to prepare like polymer membranes and has high separation factor in gas separation like inorganic porous materials,which is one of the ideal choices for gas separation.We prepared MMM by adding the UiO-66-NH₂@ICA as filler into Matrimid^?.After a series of tests,the results show that the MMM has a highest separation factor when the ratio of filler is10%and the pressure difference is 3 bar,and the separation factor reaches 64.7 while the flux is 40.14 Barrer.2.Superhydrophobic materials have a wide range of applications in oil-water separation.We prepared a hydroxyl group-containing COF:BTADHBD and subsequentlymodifieditwithglycidoland1H,1H,2H,2H-perfluorooctyltriethoxysilane（POTS）successivelytoobtain superhydrophobic COF powder:BTADHBD@Glc@POTS.The powder has a water contact angle of 153.2°.In order to carry out the oil-water separation more conveniently,we further grow BTADHBD on modified stainless steel mesh by multiple growth methods,and then use PSM to obtain stainless steel mesh support superhydrophobic COF membrane,the water contact angle of the membrane is 152.1°.Finally,we use the superhydrophobic COF membrane in oil-water separation.The separation efficiency of the stainless steel mesh for various oil-water mixtures can reach more than 99.5%,which is stable after 50 consecutive oil-water separation tests.The superhydrophobic COF membrane also has self-clean ability.The intrusion pressure of the superhydrophobic COF membrane is 44 kPa,which is higher than the general oil-water separation membrane and has high potential in practical applications.3.Amino COF is generally synthesized by reducing nitro COF,but post-treatment of this reaction have always been a challenge.We improved the synthesis of this type of COF by using water-soluble sodium hyposulfite as a reducing agent instead of stannous chloride used in the previous literature,which greatly simplifies the post-treatment steps.Removal of heavy metal ions from water is a vital environmental issue.We grafted a strong chelating group EDTA to the amino COF by PSM to prepare COF named TpPa-NH₂@EDTA which can adsorb heavy metal ions.We explored the effects of pH,metal ion concentration,and adsorption time on the adsorption performance.Experiments show that the COF can adsorb the six representative metal ions（including soft acid,transition acid and hard acid）above and exhibits high metal ion removal rate at low pH.