凝固条件对聚砜-聚乙二醇超滤膜结构和性能的影响研究

EFFECT OF COAGULATION CONDITIONS ON MORPHOLOGY AND PERFORMANCE OF PSF/PEG HOLLOW FIBER ULTRAFILTRATION MEMBRANE

以不同相对分子质量及含量的聚乙二醇(PEG)作添加剂制备聚砜(PSF)超滤膜,并考察它们对膜水通量、截留率、机械强度的影响。结果表明,添加剂PEG相对分子质量的提高可显著改善膜通量,提高PEG含量会改变铸膜液体系的相平衡关系,加速相分离的发生,在一定范围内随着PEG含量的提高,膜通量逐渐增大,当PEG的质量分数为15%时膜通量达到峰值,过量的PEG却改变铸膜液的流变性能而延迟液液相分离改变成膜结构,PEG添加量对膜机械性能无明显影响;膜渗透性随凝固浴水温升高先增加后减小,截留率趋于稳定;向凝固浴中加入与溶剂N,N-二甲基甲酰胺可延缓相分离的速度,膜结构由指状孔向海绵状结构过渡。

The molecular weight and concentration of PEG affect the pure water flux,rejection and mechanical strength.The results show that the additive increase in PEG molecular weight can significantly improve the membrane flux,PEG will increase the concentration of casting solution system,change the equilibrium relationship and accelerate phase separation.the membrane flux gradually increased with increasing the PEG concentration in a certain range,the maximum flux is Occurred when the PEG concentration is 15%,the excess PEG can increase the viscosity of casting solution,resulting in delay in the occurrence of phase separation,The PEG content has no effect on mechanical properties of membrane;permeability of membrane increased with increasing the coagulation bath temperature and then decreased,retention rates are stable;adding solvent DMF to the coagulation bath can slow down the speed of phase separation,membrane structure change from the finger hole to the network-structure.