Preparation And Adsorption Properties Of ZIFs-like Materials And ZIF-8@GQDS Composites

At present,volatile organic compounds(VOCs)are still widely present in the field of printing and packaging,which does great harm to the environment.The detection,monitoring and adsorption removal of VOCs have become a hot topic.Metal-organic Framework materials(MOFs)stand out from many porous materials because of its high specific surface area,adjustable pores and structural diversity,and have been widely used in adsorption and catalysis fields.By synthesizing MOFs composite materials,introducing substances that can specifically react with adsorbate molecules into MOFs can effectively improve the adsorption performance,which has attracted more and more researchers' attention.The surface functional groups of graphene quantum dots(GQDs)are abundant and active sites are numerous.Through functionalization,other specific functional groups can be grafted to improve the adsorption capacity of specific substances.However,how to properly introduce GQDs into the MOFs structure remains a huge challenge.In this paper,a kind of ZIFs materials and ZIF-8@GQDs composites were prepared by two synthetic routes,respectively,and GQDs was introduced into MOFs.In addition,toluene and ethyl acetate were used as VOCs mimics to evaluate the adsorption properties of the two materials.In the first synthesis route,histidine functionalized graphene quantum dots(His-GQDs)were first prepared by pyrolysis method,and then mechanically blended with zinc salt solution to obtain a kind of ZIFs materials(Zn-His-GQDs),which has the structural characteristics of ZIFs.The nitrogen adsorption-desorption isotherm of this ZIFs-like material is type ?,with an average pore diameter of about 30 nm.In the second synthesis route,ZIF-8 MOFs prepared by traditional method were combined with GQDs by solution co-deposition method.The results showed that the position of the diffraction peak in the XRD pattern of the composite did not change after the introduction of GQDs.Compared with pure ZIF-8,the specific surface area of ZIF-8@GQDs composite decreased slightly from 1368 m2/g to 1362 m2/g.The adsorption capacity of toluene was increased from 364 mg/g to 366 mg/g,and the adsorption capacity of ethyl acetate was increased from 1396 mg/g to 1401 mg/g.The prepared MOFs composites showed better removal capacity for VOCs simulants.In this paper,a kind of ZIFs material and a kind of ZIF-8@GQDs composite material were designed,and the synthesis route was optimized.By changing the amount of material added,the contact time with the simulated solution,and the pH value of the solution,the adsorption performance of the two MOFs materials on VOCs simulants was effectively analyzed.The relevant studies carried out in this paper not only provide a new idea for the synthesis of MOFs composites,but also expand the application of ZIF-8 in the field of adsorption,which has important scientific value and potential application prospects.