(國家海洋局杭州水處理技術(shù)研究開發(fā)中心, 杭州 310012)
摘 要: 隨著膜技術(shù)的發(fā)展， 20世紀(jì)80年代出現(xiàn)的納濾膜彌補(bǔ)了反滲透與超濾之間的空白。納濾膜（nanofiltration membrane, NF）又稱“疏松型”反滲透膜。 通常情況下， 膜的截留相對分子質(zhì)量界限為200～1000， 與截留相對分子質(zhì)量相對應(yīng)的膜孔徑為1~3nm， 故將這類膜稱為納濾膜。納濾膜可以截留糖類等低相對分子質(zhì)量有機(jī)物和高價(jià)無機(jī)鹽（如MgSO4等），但對單價(jià)無機(jī)鹽的截留率低（僅為10%～80%）， 具有相當(dāng)大的透過能力。由于單價(jià)鹽可以自由透過納濾膜， 使得膜兩側(cè)因離子濃度不同而造成的滲透壓差遠(yuǎn)遠(yuǎn)低于反滲透膜。 在相同通量條件下， 納濾膜所要求的驅(qū)動(dòng)壓力比反滲透膜要低得多。 一般納濾的操作壓力為0.5～1.5MPa。
由于納濾膜的這種獨(dú)特分離性能， 確定了它在水軟化和低相對分子質(zhì)量有機(jī)物純化濃縮的地位。 此外， 納濾膜能有效去除許多中等相對分子質(zhì)量溶質(zhì)，如消毒副產(chǎn)物的前驅(qū)物、 殘留農(nóng)藥和某些色素等， 因而在水凈化處理和脫色中得到廣泛的應(yīng)用。
關(guān)鍵字: 膜技術(shù); 納濾膜; 納濾; 軟化; 純化濃縮; 水凈化; 脫色
（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
