Preparation Of Reinforced AOPAN Nanofibers And PAN/PEI Porous Sponge And Its Adsorption Performance

With the continuous development of modern industry,the problem of heavy metal pollution caused by industrial wastewater discharge has attracted people's attention.How to develop new materials capable of efficiently removing heavy metal ions has become particularly important in terms of material design.Compared with traditional adsorption materials such as adsorption resin and activated carbon,electrospinning nanofibers have the advantages of small diameter,large surface area,high adsorption capacity,and fast adsorption speed.It is an ideal material for advanced treatment of industrial wastewater and drinking water.Among the numerous electrospinning nanofiber adsorbent materials,AOPAN NFs contain functional groups capable of chelating with metal ions,such as uranium,lead,copper,chromium,arsenic and mercury.With good adsorption capacity,it has become a research hotspot in the field of adsorption-type nanofibers.In previous studies,most people used PAN nanofibers to react with hydroxylamine hydrochloride to prepare AOPAN NFs.In recent years,a method for preparing an AOPAN solution by reacting polyacrylonitrile with hydroxylamine hydrochloride and then obtaining the AOPAN NFs by electrospinning has been developed.Compared with the conventional methods,the inconvenience in the operation of amidoxime treatment of large fiber membranes were avoided.but the AOPAN NF nanofiber mechanical strength is poor,easy to break,can not be used in batches,while AOPAN solution and other resins are poorly compatible,so can not be introduced through the solution miscibility method to introduce enhanced components.Aerogel is a special porous material with high porosity,low density and high surface area.It is widely used in many fields such as biology,environmental protection and catalysis.It is significant to develop simple and efficient aerogel preparation methods.In 2014,Donghua University started from electrospinning polyacrylonitrile(PAN)nanofibers,and prepared a highly elastic,low-density,ultra-light nanofiber gas through high-speed dispersion,low-temperature lyopHilization and thermal cross-linking processes.And then people further developed the technology,obtained aerogel with a variety of functions such as thermal insulation,sound absorption,oil-water separation,but so far,the aerogels electrospinning nanofiber-based which was used to adsorp heavy metal ions and organic pollutants have not been reported.Based on the comprehensive analysis of the results of the existing literature,this paper starts with two aspects:(1)In view of the problems existing in AOPAN NFs,two methods were used to introduce the enhancement components into the matrix of AOPAN NFs,and the adsorption fibers with better mechanical properties were obtained;(2)From the electrospinning nanofibers containing polyacrylonitrile(PAN)containing adsorbent,combined with techniques such as electrospinning,freeze-drying and epichlorohydrin(ECH)post-crosslinking,a porous sponge with good adsorption performance was obtained.,The main contents are as follows:1.Polyamide 66(PA66)is an ideal framework polymer because of its high strength and good abrasion resistance.In this paper,the PA66 formic acid solution with excellent mechanical properties was selected as reinforcing material for introduction into AOPAN NFs by two-nozzle opposite electrospinning process,and the adsorption properties of AOPAN/PA66 to As(?),Cr(?)and methyl orange(MO)were also studied.The results showed that the surface of AOPAN/PA66 was smooth and soft,and the strength of AOPAN/PA66 was gradually increased with the increase of PA66 content;when the mass ratio of AOPAN to PA66 is 3:1,the tensile strength and elongation of nanofibers were 6.4 MPa and 38.46%respectively.And the maximum adsorption capacities of As(?),Cr(?)and MO were 95.42 mg/g,93.48 mg/g and 48.47 mg/g.The high-strength nylon 66 fiber played an excellent template supporting role in the entire fiber membrane system,and its mechanical properties are much better than those of the coaxial electrospun fiber membrane in the previous section.2.The coaxial nanofibers(AOPAN @ PAN)with amidoxylated polyacrylonitrile(AOPAN)as shell and polyacrylonitrile(PAN)as core was prepared by using coaxial electrospinning technology.And the morpHology,composition and mechanical properties of nanofibers were characterized by transmission electron microscopy(TEM),scanning electron microscopy(SEM)and infrared(FIRT).The results show that the strength of AOPAN @ PAN coaxial nanofibers increases with the increase of PAN dosage.The tensile strength and elongation at break of nanofibers are 3.6778 MPa and 18.026%when the mass ratio of core to shell is 1:3,and the maximum adsorption capacities of Pb(?)?Cu(?)?Cr(?)and methyl orange(MO)were 151.2 mg/g?135.1 mg/g?120.48 mg/g,and 43.45 mg/g,respectively.3.The electrospinning technique and freeze-drying technique were combined to prepare a highly elastic porous PAN/PEI sponge adsorption material with PAN as carrier,polyethyleneimine(PEI)as adsorbent and epichlorohydrin(ECH)as crosslinking agent.The material could still rebound to its original height after at least 20 compressions,the rebound time was about 1 second,and it had a high compression resilience.The material did not shrink in size in water,and after being compressed in water,it could quickly expand and change back to its original shape.And the maximum adsorption capacities of Cu(?)?Cr(?),As(?)and methyl orange(MO)were 242.71 mg/g,214.14 mg/g,258.36 mg/g and 183.0627 mg/g.