Preparation And Study On Adsorption Properties Of ZIF-8@PAN Porous Carbon Nanofiber Membrane Materials

Polyacrylonitrile(PAN),a kind of good fiber-forming polymer,has been widely used in the textile industry in view of its good film-forming properties,solvent resistance,resistance to hydrolysis,oxidation resistance,good chemical stability,and excellent resistance to bacterial erosion.In particular,PAN is often used to make electrospinning nanofiber membrane materials,and emerges in the field of adsorption.However,recently,the adsorption requirements for adsorbent materials are becoming higher and higher due to increasingly complex environments.Metal-organic framework materials(MOFs)have a high specific surface area and controllability of structure size,and great potential in the field of adsorption and separation.Therefore,MOFs are used to improve the adsorption of PAN nanofiber membrane materials in this paper.First of all,the preparation method of conventional zeolitic imidazolate framework-8(ZIF-8)was selected and improved to synthesize ZIF-8 by means of a simple and eco-friendly preparation process.Then,ZIF-8 was fixed on the surface of PAN fiber membrane prepared by the electrostatic spinning method.Moreover,the ZIF-8@PAN was carbonized under high-temperature conditions to obtain nanofiber membrane materials with a porous carbon structure.The structure,morphology,adsorption performance and adsorption mechanism of the materials were studied.It is wished that the investigation of these papers could provide a new idea for the functional finishing of PAN nanofiber membrane materials and their application in industrial sewage treatment.Firstly,a uniform Zinc oxide(ZnO)coating was sputtered on the surface of PAN nanofiber film materials by magnetron sputtering,and the ZnO coating was also used as metal ion source.After solvothermal reaction with the organic ligand dimethylimidazole,the ZIF-8@PAN nanofiber membrane materials were obtained.At each stage of the preparation process,the morphology,structure and composition of the product were characterized.The results show that ZIF-8functional particles are successfully fixed on the surface of PAN nanofiber membrane materials via the situ-growth method,and these particles present the perfect structure complete and uniform size.Secondly,the ZIF-8@PAN nanofiber membrane materials were carbonized under different temperatures to obtain the porous carbon structure.The morphology and structure of carbonized materials were analyzed.The results show that the ZIF-8 loads on the surface of PAN can improve the film-forming properties of PAN nanofiber membrane materials at high temperature.ZIF-8 with the unique rhombic dodecahedron structure improves the adsorption efficiency of PAN nanofiber membrane materials.At different calcination temperatures,the ZIF-8@PAN nanofiber membrane materials show the different structures and morphology.When the calcination temperature reaches900?,the porous carbon structure of the ZIF-8@PAN materials is the most complete.The adsorption performance tests show that the ZIF-8@PAN porous carbon nanofiber membrane materials has an excellent adsorption effect on the heavy metal ion cadmium ion(Cd²⁺).Especially,the materials calcined at 900? has the best adsorption performance.Finally,the effect of different adsorption experimental conditions on the removal efficiency of Cd²⁺by the ZIF-8@PAN porous carbon nanofiber membrane materials calcined at 900? were explored.Additionally,the adsorption mechanism and recycling performance of the materials on Cd²⁺were investigated.It is found that when the temperature of water bath is 35? and the p H is7.5,the materials have the best adsorption effect on Cd²⁺.At this time,the adsorption equilibrium time is 46 h,and the adsorption efficiency could reach more than 90%.Then,the first-order and second-order kinetic simulations were used to study the adsorption mechanism of Cd²⁺when the temperature of water bath is 35? and p H is 7.5.The results show that the adsorption process is dominated by chemical adsorption.In addition,for the ZIF-8@PAN porous carbon nanofiber membrane materials,their first adsorption effect on Cd²⁺are excellent,however,the reusability needs to be further improved.