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75G 80G 100G 150G 200G Coffe water milk tea Nanofiltration (NF) - A Pressure-driven Membrane Separation Process

Nanofiltration (NF) is used to separate substances with relatively small molecular weights, such as inorganic salts or small molecular organics such as glucose and sucrose, from solvents. Nanofiltration, also known as low-pressure reverse osmosis, is an emerging field of membrane separation technology. Its separation performance is between reverse osmosis and ultrafiltration, allowing some inorganic salts and some solvents to pass through the membrane to achieve separation.
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NF Principle

Nanofiltration is a pressure-driven membrane separation process between reverse osmosis and ultrafiltration. The pore size of nanofiltration membranes is in the range of a few nanometers. It appears late compared to other pressure-driven membrane separation processes. Its appearance can be traced back to the research of J.E. Cadotte's NS-300 membrane in the late 1970s. After that, nanofiltration developed rapidly, and the membrane stacker was commercialized in the mid-1980s. Nanofiltration membranes are mostly derived from reverse osmosis membranes, such as CA, CTA membranes, aramid composite membranes and sulfonated polyethersulfone membranes.


Nanofiltration (NF) is used to separate substances with relatively small molecular weights, such as inorganic salts or small molecular organics such as glucose and sucrose, from solvents. Nanofiltration, also known as low-pressure reverse osmosis, is an emerging field of membrane separation technology. Its separation performance is between reverse osmosis and ultrafiltration, allowing some inorganic salts and some solvents to pass through the membrane to achieve separation.


In nanofiltration, under the action of higher than osmotic pressure, water molecules and a small amount of dissolved salts pass through the selective semi-permeable membrane, while other dissolved and colloid, organic matter, bacteria, microorganisms and other impurities are discharged with concentrated water. It is suitable for desalination, softening and refining of biochemical products, special foods, dyes, etc. in various process water stations.


UF(ultrafiltration), NF(nanofiltration), RO(reverse osmosis), models cover roll, flat, disc and other membrane elements, widely used in municipal sewage, electroplating wastewater, printing and dyeing wastewater, material separation, drug concentration and electrophoretic coating and other related fields.





Industrial Nanofiltration Membrane Elements

Modules

Test solution

Average water production

Stable salt rejection

Effective membrane area

GPD

m³/d

%

ft2

NJNF14040

NaCl

2300

8.7

90-98

90

8.4

MgSO4

2400

9.1

≥96

NJNF18040

NaCl

10000

37.9

90~98

400

37.2

MgSO4

10500

9.1

≥96

Test conditions

Test pressure

100psi(0.69MPa)

Test solution temperature

25℃

Test solution concentration

2000ppm

Test solution pH value

7.5

Recovery rate of one unit

15%

Application

NJNF Industrial nanofiltration membrane elements are mainly used to remove organic matter, microorganisms, viruses and most of the divalent and above metal ions in water, and retain part of sodium, potassium and other ions. Liquid separation and concentration purification process in nanofiltration membrane separation process.

NJNF24040

NaCl

2400

9.1

30-50

90

8.4


MgSO4

2000

7.5

≥97

NJNF28040

NaCl

12000

45.5

30-50

400

37.2


MgSO4

10000

37.9

≥97

Test conditions

Test pressure

100psi(0.69MPa)

Test solution temperature

25℃

Test solution concentration

2000ppm

Test solution pH value

7.5

Recovery rate of one unit

15%

Application

NJNF2:It has a lower removal rate for monovalent salts, a higher removal rate for divalent salts, and a high removal rate for TOC. The membrane element has large effective membrane area, low transmembrane pressure difference, and can remove organic compounds in water under low pressure operation.


Household Membrane Elements

Modules

Average GPD(m³/d)

Stable salt rejection %

Min. Salt rejection %

Center tubelength(mm)

Film roll

dia.(mm)

NJRO-1809

50

98

97

225.5

45.5

NJRO-1810

50

98

97

256

44

NJRO-1812

50

98

97

298

46

NJRO-1812

75

98

97

298

46

NJRO-2012

75

98

97

298

48

NJRO-2012

100

98

97

298

48

NJRO-2012

125

98

97

298

48

NJRO-2812

300

97

96

298

68

NJRO-3012

400

97

96

298

73

NJRO-3013

400

97

96

333

67.8

NJRO-3013

600

97

96

333

67.8

NJRO-3020

800

97

96

513.8

79.5

Test conditions

Test pressure

60psi(0.41MPa)

Test conditions

Test pressure

25℃


Test solution temperature

250ppm


Test solution concentration

6.5~8.5


Test solution pH value

15%

Application

NJRO household reverse osmosis membrane elements operate under extremely low pressure conditions, and are mainly used in various household pure water machines, hospitals, laboratory pure water, and for the treatment of tap water, well water and other low-salinity water sources.


Product Advantages

Industrial Nanofiltration Membrane Elements

Industrial Nanofiltration Membrane Elements
  • High temperature resistance, acid and alkali resistance.

  • Widely used in drinking water, food and beverage, medicine, reclaimed water reuse, wastewater treatment and other industries;

  • Rejection of soluble organic substances can be affected by the size and shape of the substance's molecules, usually in the range of 100-1000.

  • With selective separation characteristics, it has a lower rejection rate for monovalent salts such as sodium chloride, and a higher rejection rate for divalent salts or polyvalent salts, usually above 90%.

Household Membrane Elements

Household Membrane Elements Household Membrane Elements
  • Has a high water flux.

  • Has strong mechanical stability.

  • Pore size distribution is uniform, water quality is high, anti-pollution wall.

  • High pressure resistance, can be used under different pressure conditions.

  • High-performance membrane elements guarantee the production of high-quality water.

Future Development

Nanofiltration separation is a new type of membrane separation technology, and its technical principle is similar to mechanical sieving. However, the nanofiltration membrane itself is charged. This is an important reason why it still has high desalination performance under very low pressure and the membrane with molecular weight cut off of several hundreds can also remove inorganic salts.

Nanofiltration separation is more and more widely used in electronics, food and pharmaceutical industries, such as ultrapure water preparation, high concentration of fruit juice, peptide and amino acid separation, antibiotic concentration and purification, whey protein concentration, nanofiltration membrane-biochemical reactor In the actual separation process such as coupling. Compared with ultrafiltration or reverse osmosis, nanofiltration process has poor retention of monovalent ions and organic compounds with molecular weight below 200, but has higher removal of divalent or multivalent ions and organic compounds with molecular weight between 200 and 500. Based on this characteristic, the nanofiltration process is mainly used in the softening and purification of water, as well as the separation, classification and concentration of substances with a relative molecular mass in the 100-level (such as dyes, antibiotics, peptides, polysaccharides and other chemical and biological engineering products classification. and concentration), decolorization and deodorization, etc. It is mainly used to remove hardness components such as Ca and Mg ions, trihalomethane intermediates, odor, chroma, pesticides, synthetic detergents, soluble organics, and evaporation residues in drinking water.

With the continuous improvement of awareness of environmental protection and comprehensive utilization of resources, people hope to realize the recovery of valuable substances while treating wastewater. For example, soybean whey wastewater contains about 1% of oligosaccharides and a small amount of salt. The calcium sulfite waste liquid in the preparation of chemical fiber pulp and paper pulp by the sulfate method contains 2% to 2.5% of six-carbon sugar and five-carbon sugar, and the waste molasses in the sugar industry contains a small amount of salt and so on.

NF separation is a green water treatment technology, which can replace traditional sewage treatment methods with high cost and cumbersome process in some aspects. Its technical characteristics are: it can intercept organic compounds with molecular weight greater than 100 and multivalent ions, and allow small molecular organic compounds and monovalent ions. Ion permeation; can operate under harsh conditions such as high temperature, acid and alkali, and is resistant to pollution; low operating pressure, high membrane flux, and low operating cost of the device; it can be combined with other sewage treatment processes to further reduce costs and improve treatment effects .In water treatment, NF membrane is mainly used for the treatment of solvent-containing wastewater, which can effectively remove the color, hardness and peculiar smell of water. NF membrane has been successfully used in sugar, pulp and paper with its special separation performance. Wastewater treatment in industries such as electroplating, machining, and recovery of chemical reaction catalysts.

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