Study On The Adsorption Properties Of ZIF-8/GO Composites For Toluene Containing Water Vapor And Its Optical Properties

As an important material widely used in chemical industry,toluene(C7H8)is largely present in the exhaust gases emitted from industrial production.However,industrial tail gas often contains water vapor,which affects the adsorption of adsorbent on target gas.How to effectively remove toluene in the high-humidity exhaust has been a hot research topic for scholars.Metal Organic Frameworks(MOFs)is a kind of coordination polymer with periodic mesh three-dimensional structure.They have adjustable pore size,huge specific surface area and large porosity,which makes MOFs have a broad development prospect in the field of gas adsorption.Zeollitic Imidazolate Frameworks(ZIFs),as a family of MOFs,have better chemical stability.Graphene Oxide(GO)is obtained by the oxidation of graphene.It has a large number of oxygen functional groups on the surface of graphene oxide,which can provide a number of binding sites for its combination with MOFs,thereby making graphene oxide a good platform for the growth of MOFs.Therefore,the preparation of MOFs/GO composites is expected to obtain an excellent adsorbent.In this paper,ZIF-8 crystal materials and ZIF-8/GO composites with different graphene oxide contents were prepared at room temperature with methanol as a solvent.The prepared samples were characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA),scanning electron microscope(SEM)and specific surface area(BET).The data obtained from the characterization tests showed that the specific surface area of the composite was less than that of pure ZIF-8,and the surface morphology and specific surface area are regulated by the content of graphene oxide.There are synergistic effects in the ZIF-8/GO composites,and the composites have the advantages of ZIF-8 and graphene oxide.Besides,the photoluminescence spectra of ZIF-8 and composite materials were tested.It was found that the emission peak of ZIF-8 is around 450nm and the luminescence intensity of composite with similar spectrum of ZIF-8 was very weak.This work laid the foundation for the research of MOFs sensor in the future.By using the synthesized ZIF-8 and ZIF-8/GO composites as adsorbents,the adsorption breakthrough experiments of toluene gas under the relative humidity of 55%were carried out,and the breakthrough curves of different materials on toluene were obtained.The experimental results show that with the increase of graphene oxide in composites,the adsorption amount of toluene shows a trend of rising first and then decreasing.ZG-4 has the highest adsorption capacity of 116mg/g,which is 19%higher than that of pure ZIF-8.The further experiments of toluene adsorption under different humidity showed that the presence of water vapor had a negative effect on the adsorption of toluene,but even at 80%high humidity,the adsorption capacity of the composite was still higher than that of ZIF-8.Besides,the cyclic adsorption experiments of composite materials proved that the material had good reusability.The above results indicate that ZIF-8/GO composites are effective adsorbents for adsorbing toluene gas under higher humidity conditions.