Preparation Of Nanofiber Composite Aerogels And Theri Application In Water Pollution Treatment

Worldwide,heavy metal pollution and organic dye pollution have become difficult problems in the field of sewage treatment because of their high toxicity and difficult treatment.Among the existing treatment methods,the adsorption method has become an excellent choice for sewage treatment because of its advantages of simple operation,wide application range and high treatment efficiency.Nanofiber aerogels show unique advantages in the field of adsorption because of their large specific surface area,high porosity and easy composite modification.However,most of the existing nanofiber aerogels exhibit poor mechanical properties due to weak structure,which greatly limits their practical application.Based on this,this paper proposes to prepare nanofiber composite aerogels with excellent mechanical properties,strong practicability and excellent adsorption effect in view of the pollution of heavy metals and organic dyes in water,and then use them for the adsorption treatment of heavy metals and organic dyes.PPy/CA nanofiber aerogels(PNFA)and reduced graphene oxide(rGO)/CA nanofiber composite aerogels(GNA)were developed.The obtained nanofiber composite aerogels all exhibit excellent adsorption capacity,and have excellent mechanical properties such as ultra-lightness,pressure resistance,good mechanical stability and shape design.It has potential practical application value.The specific research work is as follows:(1)Using electrospun CA nanofibers as the skeleton material and pyrrole as the multifunctional crosslinking agent,a porous PNFA with polypyrrole coated with cross-linked on the fiber surface was prepared by low-temperature in-situ polymerization.The composition,structure and mechanical properties of PNFA were characterized by SEM,TEM,FTIR,XPS,Raman,stress-strain curve and other test methods.PNFA has good soft elasticity,and the compressive strength is 14.49 kPa when the compression variable is 80%.When the pH=2 and the initial concentration of the adsorbate solution is 350mg/L,the saturated adsorption capacity of PNFA-2 to Cr(Ⅵ)can reach 322.58mg/g.Through kinetic and thermodynamic analysis,it is known that the adsorption of Cr(Ⅵ)by PNFA is mainly based on the chemical adsorption of monolayers.In addition,cycling experiments found that the adsorption capacity of PNFA can be stably maintained above 300 mg/g within 5 cycles.(2)Using GO sheet layer as the skeleton material,the sheet layer was supported,separated and connected by electrospinning CA nanofiber,and the internal loose and porous GNA was prepared by GO high-temperature reduction.The composition,structure and mechanical properties of GNA were characterized by SEM,FTIR,XPS,Raman,compression and other test methods.GNA exhibits good soft elasticity and pressure resistance,and when the compressibility variable is 50%,the compressive strength can reach 28.33 kPa,and the shape of GNA can be well recovered after pressure release.GNA showed good adsorption capacity for MB in water,and when the pH of the adsorbate solution was 10 and the initial concentration was 40 mg/L,the saturated adsorption capacity of GNA-1.5 for MB could reach 122.74 mg/g.Through kinetic and thermodynamic analysis,it is known that the adsorption of MB by GNA is mainly based on the chemical adsorption of monolayers.In addition,the adsorption of MB by GNA can be maintained at more than 70%for 5 cycles.