Preparation And Properties Of Modified Polyacrylonitrile Hollow Fiber Membranes

In order to improve the capability of polyacrylonitrile(PAN)hollow fiber membrane to remove methylene blue dye(MB),this study modified the PAN hollow fiber membrane by adopting the method of hydrolytic coordination.PAN was used as a membrane-forming component,and N,N-dimethylformamide(DMF)was used as a solvent to prepare hollow fiber membrane by wet spinning.The obtained hollow fiber membrane that was used as a substrate was hydrolyzed with sodium hydroxide aqueous solution and coordinated with Fe²⁺to prepare iron oxide modified hollow fiber membrane,and the prepared membrane was used as a filter medium to catalyze hydrogen peroxide(H₂O₂)to oxidatively decompose MB.The morphology and elemental changes of hollow fiber membranes obtained before and after modification were analyzed by thermal field emission scanning electron microscopy and X-ray photoelectron spectroscopy,and the composition of particles on the inner surface of the prepared membrane was identified by using X-ray diffractometer.The research results showed that the particles loaded onto the hollow fiber membrane were mainly composed of Fe OOH and Fe₂O₃.Iron oxide modification could give the PAN hollow fiber membrane capability to catalyze hydrogen peroxide(H₂O₂)to oxidatively decompose MB.After 30 cycles,the modified PAN hollow fiber membrane still showed a removal efficiency of 90.5%for MB,and the flux of MB aqueous solution was 11.4 L/m²·h.In this study,the blending modification was used to improve the performance of the PAN hollow fiber membrane.First,PAN was used as a membrane-forming component;MXene,Fe OOH or the copolymer of acrylic acid with maleic anhydride[P(AA-co-MA)]as a blending component;DMF as a solvent;water as a non-solvent to prepare hollow fiber membrane by wet spinning.The hollow fiber membrane modified by blending PAN with the above-mentioned substance was applied to treat the water polluted by MB.The morphology and chemical groups of the blended modified hollow fiber membrane were analyzed by thermal field emission scanning electron microscope and Fourier transform infrared spectrometer,and the dye-rejecting mechanism of the P(AA-co-MA)blended modified hollow fiber membrane was studied.The research results showed that the MXene modification could increase the elongation at break of the hollow fiber membrane.Under a pressure of 0.04 MPa,blending with Fe OOH,whose mass concentration was equal to 6%,could significantly improve the MB-removing capability of the PAN hollow fiber membrane.After 6 cycles,the Fe OOH blended modified PAN hollow fiber membrane still showed a removal efficiency of 90%for MB.The P(AA-co-MA)blending modification could effectively improve the mechanical properties of the PAN hollow fiber membrane,enhance its surface electronegativity,and improve the capability of PAN hollow fiber membranes to treat the water containing MB.After 15 cycles,the P(AA-co-MA)blended modified PAN hollow fiber membrane still showed a removal efficiency as high as 90%for MB.After 30 cycles,the hollow fiber membrane still could remove 73%of MB from the solution,and the flux of MB aqueous solution was as high as 37.5 L/m²·h.