Preparation And Properties Of Polyacrylonitrile/Modified Hydroxyapatite Composite Adsorption Fribers

Heavy metal ions have a great impact on industrial production and human health. Some heavy metal ions such as lead, mercury, cadmium can result in human cancer. Therefore, the removal and recovery of heavy metal ions in industrial production is a long-term meaningful research subject.In this thesis, the coupling agent KH-570and acrylic acid (AA) are used to modify HAp. The composite films and composite fibers are obtained via wet spinning after blending modified HAp(MHAp) and polyacrylonitrile(PAN) and UV grafting MHAp onto PAN. The fourier transform infrared spectrometer(FTIR), scanning electron microscopy(SEM), thermogravimetry(TG), differential thermal (DSC), light scattering, Zeta potential and X-ray diffraction (XRD) are employed to characterize MHAp, PAN/MHAp blend composite films and PAN/MHAp photografting composite films. The mechanical properties and adsorption capactiy of MHAp, PAN/MHAp composite films and PAN/MHAp composite fibers are studied. The preparation process of MHAp, PAN/MHAp composite films and PAN/MHAp composite fibers are discussed using the orthogonal optimization and single-factor analysis.The FTIR,TG-DSC, light scattering, Zeta potential and XRD results of MHAp-KH570show that KH-570silane coupling agent is combined with the surface of HAp and exerts little influence on the crystal structure of HAp. The absolute value of Zeta potential of MHAp-KH570increases, resulting in improved stable dispersion and decreased agglomeration of MHAp particles. The size of nanoscale MHAp particles is reduced from272.8nm to166nm. Cd2+adsorption capacity increases with the increment of weight gain. The optimum preparation process of HAp-KH570are KH-570volume fraction of5%, volume ratio of ethanol/water of8.5:1.5, hydrolysis time of30min, pH value of4, coupling time of2h, coupling temperature of70℃and evaporated temperature of80℃using the orthogonal optimization. The optimum preparation process of HAp-KH570, which make tensile strength and adsorption capacity of PAN/HAp-KH570blend composite film good, are coupling agent KH-570volume fraction of3%, volume ratio of ethanol/water of8.5:1.5, hydrolysis time of30min, pH value of6, coupling time of60min, coupling temperature of 65℃and evaporated temperature of65℃. Through the analysis of orthogonal optimization and single factors, good tensile strength and adsorption capacity can be obtained when the preparation process of MHAp-KH570are coupling agent KH-570volume fraction of5%, volume ratio of ethanol/water of9:1, hydrolysis time is1h, pH value of6, coupling time of30min, coupling temperature of50℃, evaporated temperature of50℃, UV grafting time of8min and initiator mass fraction of9%.The MHAp-AA and PAN/MHAp-AA photografting composite film are characterized by SEM, FTIR, TG-DSC, light scattering and Zeta Potential. The results show that the peak of MHAp-A A at1637cm-1is attributed to-C=O stretching vibration. The-C=O vibration peaks at1631cm-1of pure PAN and at1637cm-1of MHAp overlap and shift to higher wavenumber, which proves photograft of MHAp onto PAN. Nanoscale MHAp particles are well dispersed and distributed in PAN/MHAp-AA photografting composite film. The thermal stability of composite material is improved due to photograft. The absolute value of Zeta potential is enhanced. The size of MHAp-AA nanoscale particles is reduced from272.8nm to253nm. The Cd2+adsorption capacity of photografting composite film slightly decreases and the tensile strength increases. Through orthogonal optimization, the optimum prepartion prccess of MHAp-AA are mass fraction of acrylic acid of40%, p-toluenesulfonic acid mass fraction of8%, hydroquinone mass fraction of0.5%, heating time of2h and drying time of4h.The tensile strength of two PAN/MHAp photografting composite fibers is greater than blend composite fibers. The adsorption capacity is slightly less than the blend composite fibers. The best Cd2+adsorption capacity of PAN/MHAp-KH570and PAN/MHAp-AA photografting composite fibers obtained from optimum spinning process of PAN/HAp blend fibers are86.2and82.3mg·g-1, respectively. The best tensile strength of PAN/MHAp-KH570and PAN/MHAp-AA photografting composite fibers obtained from optimum spinning process are3.19and2.91cN·dtex-1, respectively. The improvement of tensile strength of photografting composite fibers indirectly confirms that MHAp is photografted onto PAN.