Nanofiltration (NF) is a membrane liquid-separation technology sharing many characteristics with reverse osmosis (RO). Unlike RO, which has high rejection of virtually all dissolved solutes, NF provides high rejection of multivalent ions, such as calcium, and low rejection of monovalent ions, such as chloride.
What is NF membrane made of?
Nanofiltration membranes are mostly composite membranes, consisting of three layers:
Non-woven fabric base layer (~150μm) : Provides mechanical support (polyester fiber).
Porous support layer (~50μm) : Polysulfone/polyethersulfone, forming a microporous structure.
Ultra-thin separation layer (~0.1μm) : Polyamide, which determines the separation performance (molecular weight cut-off 100-1000 Da).
The MAXIE key innovation: Surface modification of the separation layer (such as grafting negatively charged groups) to enhance the retention rate of divalent ions (Ca²⁺, SO₄²⁻).
What is the difference between RO and NF?
NF delivers slightly coarser filtration than RO, with the ability to remove particles as small as 0.002 to 0.005 μm in diameter. NF is a relatively recent technology that was developed mainly for potable water generation.
Is nanofiltration better than reverse osmosis?
Nanofiltration requires less energy and produces higher fluxes at low pressures; works best for applications that do not require a feed stream completely free of dissolved solids. Reverse Osmosis, on the other hand, is the solution for absolute purified water although it requires more energy to produce.
Does nanofiltration remove chlorine?
NF can reduce or remove TDS, hardness, color, agricultural chemicals, high molecular-weight, fulvic materials (which can form trihalomethanes when chlorinated). NF is also used to remove both organics and inorganics from different wastewaters.
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