Preparation And Adsorption Properties Of Polyacrylonitrile Based Porous Fiber Membranes Based On Electrospinning Technique

With the development of modern industry,air and water pollution have become increasingly concerning.Currently,the concentration of CO₂ in the atmosphere has increased to 416 ppm,which is 136 ppm higher than that before the industrial era.The gradual increase of CO₂concentration in the atmosphere may have adverse effects on global environmental processes,such as long-term increases in global temperatures,changes in rainfall patterns,ocean acidification,species extinction,and polar ice melting.In addition,water eutrophication originates from the excessive discharge of phosphorus containing wastewater,which can cause a sharp decline in dissolved oxygen,leading to the extinction of aquatic organisms.Therefore,it is crucial to control the emissions of CO₂ and phosphorus,and adsorption methods haves the advantages of simple operation,high treatment efficiency,and easy recovery,which are widely used.Electrospinned nanofiber membranes（NF）are a new type of adsorbent material that not only possesses all the characteristics of carbon based materials,but also provide an adjustable porous fiber structure and can serve as a matrix to load active nanoparticles,solving the problem of equipment blockage caused by particle/powder adsorbents.Therefore,NF has a broad application prospect in the field of adsorption.Based on this,this work reports the preparation of porous carbon fiber membranes and MIL-101（Fe）/PAN nanofiber membranes by electrospinning technique,and investigates their adsorption performance for CO₂ and phosphate ions.The specific work is as follows:Porous carbon nanofiber membranes（XPAN/YPVP-CNF and XPAN/YPEG-CNF）were successfully prepared by the process of electrospinning pre-oxidation and carbonization,in which polyacrylonitrile（PAN）is used as a matrix,polyvinyl pyrrolidone（PVP）and polyethylene glycol（PEG）are used as pore-forming agents,respectively.The morphology and structure analysis showed that the introduction of pore-forming agents can effectively increase the porosity of carbon fiber membranes.At the same time,the higher the content of pore forming agent,the greater the specific surface area.Compared with pure PAN carbon membranes,porous carbon fiber membranes exhibit enhanced adsorption performance for CO₂.Studies have shown that both specific surface area and N type have an impact on the ability of porous carbon fiber membranes to capture CO₂.When the specific surface area is greater than 400m².g^-1,Pyridinic N and Pyrolic N play a dominant role in the adsorption of CO₂,and when the specific surface area is less than 400 m².g^-1,the specific surface plays a leading role in the adsorption of CO₂.MIL-101（Fe）/PAN/PVP fiber membrane was synthesized by electrospinning using MIL-101（Fe）as the active species for phosphate adsorption,PAN as the substrate,and water-soluble PVP as the pore-forming agent.After removing the PVP by water washing,a porous MIL-101（Fe）/PAN nanofiber membrane（MIL-101（Fe）NF）was successfully prepared.Morphological and structural analysis showed that PAN uniformly wrapped the MIL-101（Fe）nanoparticles,which on only improved the stability and dispersion of nanoparticles,but also increased the active exposure area of MIL-101（Fe）due to the porosity of the PAN fiber.MIL-101（Fe）NF exhibited excellent phosphate removal performance,which was consistent with the Langmuir monolayer adsorption model,and the maximum removal capacity reached 131 mg.g^-1.In the presence of competitive ions such as Cl^-,NO₃^-and SO₄^2-,the adsorption performance of MIL-101（Fe）NF for phosphate can still maintain about 70%,indicating its anti-interference properties.In addition,stability experiments showed that pure MIL-101（Fe）particles were unstable during the adsorption process and continuously released iron ions,while no iron ions were released during the adsorption process of MIL-101（Fe）NF,indicating that MIL-101（Fe）NF has the potential to be applied to practical water bodies environment.Figure[30]table[9]reference[139]...