Structural Design And Performance Study Of Braided Tube Reinforced PFA Hollow Fiber Membrane

Water resources shortage and environmental pollution have seriously restricted the national economy and society development.Membrane separation technology is widely concerned due to its simple operation,low consumption and no phase transition.The rapid development of membrane separation technology makes a higher demand for the membrane materials,which not only needs to maintain high rejection accuracy and permeability,but also need to have excellent mechanical strength.Poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether)(PFA)has excellent chemical stability,physical mechanical property,non-viscosity,aging resistance and thermal stability.As a new kind of fluoropolymer,PFA overcomes the disadvantages of polytetrafluoroethylene(PTFE)as"insoluble and infusible"and has a great application prospect.In this paper,the braided tube reinforced PFA hollow fiber membrane was prepared by dipping method and concentric circles compound spinning method,and the structure and performance were also studied.The poly(m-phenyleneisophthalamide)(PMIA)fiber braided tube reinforced PFA/GE hollow fiber membrane was prepared by dipping method with the PFA and graphene(GE)as membrane-forming polymer and inorganic nanoparticles additive,respectively.The influence of different sintering temperature and GE content on the membrane structure and oil-water separation performance was tested.The results indicated that with sintering temperature increasing,the kerosene flux decreased.In addition,with GE content increasing,the water contact angle,roughness,and porosity of PFA/GE hollow fiber membrane decreased,the kerosene flux increased initially and then decreased,and the oil-water separation efficiency increased to 99.5%.When the GE content was 0.2%,the PFA/GE hollow fiber membrane exhibited excellent lipophilicity.Under the pressure of-0.02 MPa,the separation efficiency of the membrane for different oils(kerosene,diesel,cyclohexane,etc.)was higher than 97%,and the membrane had good demulsification ability.In addition,the membrane had good recycling performance,and the flux recovery rate remained above 80%after 4cycles.The glass fiber braided tube reinforced PFA hollow fiber membrane was designed by concentric circles compound spinning method with the poly(vinyl alcohol)(PVA)as a carrier.The effects of sintering temperature on membrane surface structure,lipophilicity,heat and solvent resistance were investigated.The results showed that the appropriate sintering temperature could improve the porous surface and loose inner cavity structure of PFA hollow fiber membrane.After sintering,the residual PVA in the membrane could produce synergistic effect with PFA,giving the membrane good toughness,while maintaining excellent heat and solvent resistance.The kerosene flux could reach 482.92 L·m^-2·h^-1 at 70?,and in the treatment of non-aqueous solution dyeing system,the membrane operated stably within 4 h,the N,N-dimethyl acetamide(DMAc)flux and iron oxide red retention could reach 31.83 L·m^-2·h^-1 and 99.7%,respectively.