(国家海洋局杭州水处理技术研究开发中心, 杭州 310012)
摘 要: 随着膜技术的发展， 20世纪80年代出现的纳滤膜弥补了反渗透与超滤之间的空白。纳滤膜（nanofiltration membrane, NF）又称“疏松型”反渗透膜。 通常情况下， 膜的截留相对分子质量界限为200～1000， 与截留相对分子质量相对应的膜孔径为1~3nm， 故将这类膜称为纳滤膜。纳滤膜可以截留糖类等低相对分子质量有机物和高价无机盐（如MgSO4等），但对单价无机盐的截留率低（仅为10%～80%）， 具有相当大的透过能力。由于单价盐可以自由透过纳滤膜， 使得膜两侧因离子浓度不同而造成的渗透压差远远低于反渗透膜。 在相同通量条件下， 纳滤膜所要求的驱动压力比反渗透膜要低得多。 一般纳滤的操作压力为0.5～1.5MPa。
由于纳滤膜的这种独特分离性能， 确定了它在水软化和低相对分子质量有机物纯化浓缩的地位。 此外， 纳滤膜能有效去除许多中等相对分子质量溶质，如消毒副产物的前驱物、 残留农药和某些色素等， 因而在水净化处理和脱色中得到广泛的应用。
关键字: 膜技术; 纳滤膜; 纳滤; 软化; 纯化浓缩; 水净化; 脱色
（Research and Development Center of Water Treatment Technology, SOA, Hangzhou 310012, China）
Abstract:The appearance of nanofiltration membrane(NF) in 1980s fills in the gap between reverse osmosis(RO) and ultra-filtration. Normally, the molecular mass cutoff(MWCO) range is 200～1000, and its relative pore size is 1-3nm, so this membrane is called as NF. NF can retain low relative molecular mass organism and high-valent mineral salt, such as MgSO4, but to univalent mineral, its rejec is low(10%～80%), that is to say, univalent mineral salt can permeate NF freely, which makes the difference of permeation pressure between the two sides of the membrane due to different ion concentration, is much lower than that of RO membrane. In the same flux, NF requires much lower driver pressure than RO membrane. The operation pressure of NF is 0.5～1.5MPa. The particular separating property of NF confirms its status in water softening and low relative molecular mass organism purification and concentration. Furthermore, NF can effectively remove many middle molecular mass solutes, such as the pre-substance of side-products of disinfection, residual pesticide, some pigment. So NF is widely used in water purification and decoloring.
Key words: membrance technolygy; nanofiltration membrane; nanofiltration; softening; purification and concentration; water purification; decoloring
