水蒸气在高分子膜中的透过行为与气体膜法脱湿

Transfer behavior of water vapor in polymer membranes and dehumidification of gases by membrane separation

在气体膜分离中,水蒸气的分离过程比其它非凝聚性气体更复杂,因为水分子可以通过氢键和聚合物链节中极性基团发生作用,使聚合物被溶胀、塑化;水分子自身可通过分子间氢键聚集成簇,这些因素导致了水分子在膜中的透过行为不再符合其它气体的透过规律.水蒸气在极性高分子膜中较高的渗透能力会在膜的下游侧产生浓差极化现象,消除浓差极化现象才能使水蒸气透过正常进行.膜材料的选择要权衡亲水性和疏水性,共混和嵌段共聚是解决这一矛盾的有效手段.水蒸气在高分子膜中的较高透过能力使其用于气体膜法脱湿成为可能.现以压缩空气膜法脱湿为例,介绍了影响膜法脱湿效率的主要因素,也介绍了气体膜法脱湿的其它应用领域.

In membrane separation of gases,the separation process of water vapor is more complicated than that of other noncondensing gases.The interaction of water molecule and the polar group in polymer chain by hydrogen bond makes the polymer to be swollen and plasticized.Water molecule can also be gathered to form cluster by self-hydrogen bond.Because of these factors,the transfer behavior of water vapor in polymer membranes is different from that of other gases.The high permeability of water vapor in polar polymer membranes will result in concentration polarization in downside of membrane.In order to permeate water vapor through membrane continuously,concentration polarization should be eliminated in some way.The balance of hydrophilisity and hydrophobisity of membrane should be thought when a membrane material is chosen.Blend and block copolymerization can be used to adjust the balance.It is possible that water vapor is removed from other gases by membrane separation because of the high permeability of water vapor in membrane.In this paper,some major factors to influence separation efficiency in the dehumidification of compressed air were described and some other applications of dehumidification by membrane separation were introduced.