Preparation Of Polyacrylonitrile/Hydroxyapatite Composite Films And Study On The Adsorption Property Of Pb²⁺

In recent decades,increased industrial activity has led to the discharge of various pollutants,including large amounts of toxic heavy metals such as lead,copper,cadmium and chromium.If these pollutants are discharged directly into the water in large quantities,they will have adverse effects on the ecology and human health.The contradiction between the serious deterioration of water quality and the growing demand for clean water presents us with serious challenges.Therefore,the world urgently needs to develop a simple,low cost,high efficiency environmental treatment technology to overcome this global crisis.Electrospinning is a simple and efficient polymer technology for the preparation of nanofiber materials.The nanofibers produced by electrospinning have great advantages in the adsorption of heavy metal ions.Polyacrylonitrile fibers prepared by electrospinning have excellent porosity and large specific surface area,and their synthetic fibers also have cheaper prices and excellent tensile strength.However,polyacrylonitrile fibers are hydrophobic,which limits their further application in wastewater treatment.In this paper,hydroxyapatite is attached to the electrospinning polyacrylonitrile fiber film by three different preparation methods,namely,blending,electrostatic co-spraying and surface deposition.Hydroxyapatite has good adsorption property and hydrophilicity for Pb²⁺,while overcoming the shortcomings of easy agglomeration.Moreover,the advantages of electrostatic spinning polyacrylonitrile fiber film such as high porosity,high specific surface area and easy recovery are used to improve the advantages of the nanofiber composite in adsorption.SEM,FT-IR and XRD characterization methods were used to analyze the structure of the composite materials.and different pH,temperature and time experiments were used to explore the adsorption properties of Pb²⁺.Different electrospinning methods were identified the differences in the characterization and properties of the composite materials prepared.Specific research contents are as follows:1.PAN/HAP blending Composite film were prepared by electrostatic spinning by blending polyacrylonitrile and hydroxyapatite.The surface of PAN/HAP fibers becomes rough.After adding hydroxyapatite,the surface of the fiber was changed obviously.In the part of adsorption experiment,the influences of different proportions of raw materials,pH value,adsorption time and adsorption temperature on the adsorption capacity were discussed.The results showed that the adsorption of Pb²⁺by the composite film conforms to the quasi second-order kinetic model and Langmuir isothermal model.At 318 K,pH=6 and adsorption time 60 min,the maximum adsorption capacity was 169.81 mg/g.2.PAN-HAP composite film were prepared by electrospraying hydroxyapatite and electrospinning polyacrylonitrile fibers simultaneously.The hydroxyapatite spacers on PAN-HAP fiber membranes are aggregated into spheres and dispersed among the nanofibers.In the adsorption experiment part,the effects of pH value,adsorption time and adsorption temperature on the adsorption capacity were discussed.The results show that the adsorption of Pb²⁺by the composite film conforms to the quasi-second-order kinetic model and Langmuir isothermal model.At 318 K,pH=6 and adsorption time 60 min,the maximum adsorption capacity was 392.15 mg/g.3.Through electrostatic spinning polyacrylonitrile composite film,using sodium hydroxide alkaline treatment.Then,the PAN@HAP surface deposition nanofiber membrane was prepared by soaking in calcium-phosphorus oversaturation solution and depositing hydroxyapatite on the polyacrylonitrile surface.After soaking for three days,sheets of hydroxyapatite appeared on the surface of PAN@HAP film.In the adsorption experiment,the effects of deposition time,pH value,adsorption time and adsorption temperature on the adsorption capacity were discussed.The results show that the adsorption of Pb²⁺by the composite film conforms to the quasi second-order kinetic model and Langmuir isothermal model.At 318 K,pH=6,adsorption time 60 min,the maximum adsorption capacity is 331.93 mg/g.