Modification And Application Of Magnetic Nanofiber Mats

Electrospinning is a simple method for preparing nanofibers. With the rapid development of electrospinning , great amounts of polymers, inorganic substances and organic-inorganic complex marials can be used to prepare nanofibers by the electrospinning method. Because of e advantages such as high specific surface area and small diamer,nanofibers are widely used in fields of environment, eney,biological medicine and so on.When the size of materials is nanoscale, the property will m山ate,which can exhibit unique properties. Take magnetic nanoparticles for exampe, they not only show the nature of nanomaterials(the quantum size effect, surface effect and so on), but also enjoy the property of magnetic materials(superparamagnetism, single magnetic domain structure and magnetic properties of high coercivity). Magnetic nanoparticles are often used to prepare magnetic, magnetic memory materials and catalytic materials. However magnetic nanoparticles have some shortcomings such as weak dispersion and agglomeration, these shortcomings limit their applications. The problem can be solved easily by magnetic nanofibers prepared via electrospinning.Magnetic nanofibers show e natures of both nanomaterials and magnetic materials, which led to a hot sUidy in many field. Based on at reason in this work we used magnetic nanofiber mats as substrate materials to do some modification research in the under two aspects:1. magnetic nanofiber mats were produced by electrospinning and horseradish peroxidase enzyme(HRP) was immobilized on the nanofiber mats, then they were used to deal with phenol wastewater,(2) magnetic nanofiber mats were modified by sulfydryl on the surface, then used for the adsorption of heavy metal ions. Specific research connts are as follows:1. Magnetic nanoparticles were prepared by chemical coprecipitation,and then dispersed evenly in polyacrylonitrile(PAN) spinning ,and nanofibers were got by electrospinning. The surface morphology and structure were analyzed. The results showed that after e adding of magnetic particles,e surface of nanofibers became rough, and e size of nanofibers was increasing. With the increasing of e adding magnetic particles, the saturation magnetization(Ms) of the resulting nanofibers increased gradually. Then the magnetic nanofiber mats were modified by the surface coating of dopamine and following enzyme immobilized by the crosslinking of glaraldehyde(GTA). The degdation efficiency of phenol and activity of enzyme modified nanofiber mats were studied. The experimental results showed that when the pH was 7 and 0.1 mg/mL enzyme was in use, the activity of immobilized enzymes was highest.This is because e microscopic magnetic field formed by magnetic nanoparticles affecd e spin dynamics and inrsyem crossing of free Hidicals, which affecd e reactions between free dicals. So the enzyme catalytic reaction rate would be changed, the magnetic particles produce magnetic synergy to HRP enzyme catalytic reaction. Enzyme modified magnetic enzyme nanofiber mats were used to deal with phenol waswater, when pH was 7, enzyme modified magnetic enzyme nanofiber mats 1.0 mg/L in use, the molar ratio of phenol and H2O2 was1:1, and e amount of PEG was 0.01 removal efficiency of phenol was optimization. After 5 times usage, the degradation efficiency still remained 50%.2. Magnetic nanofiber mats amount of magnetic particles was fixed at 30 wt.0/0) were coated wi dopamine on e surface, and en ATRP was ud to grafted GMA. Finally, magnetic nanofiber mats containing sulfydryl on e surface was prepared by e episulfide reaction and ring opening reaction. The obtained modified magnetic nanofiber mats were used to study the adsorption of heavy metal ions. We studied e influence of pH and e initial concentration of Hg2+ on e adsorption efficiency of magnetic nanofiber mats. Results showed that when e pH was 6, adsorption efficiency was optimum, and wi比e increasing of the initial concenation of Hg2+ ions, the equilibrium adsorption amount is bigger. Adsorption eq山librium reached within 30 minutes, and saturated adsorption capacity was 53.6 mg/g. The research result of adsorption kinetics, isothermal adsorption and e cycle adsorption performance indicated that adsorption process was matching the pseudo-second-order model and Langmuir isotherm adsorption and after three times usage, the adsorption capacity remained90%.