The industrial application of ultrafiltration membrane is very wide, has become one of the new chemical unit operation. Used for separation, concentration, purification of biological products, pharmaceutical products and the food industry; also used for blood treatment, wastewater treatment and ultrapure water preparation in the terminal processing device. In our country has successfully utilized ultrafiltration membrane for the concentration and purification of Chinese herbal medicine. Ultrafiltration membrane with the progress of technology, its screening function will certainly be improved and strengthened, the contribution of human society will be more and more. Ultrafiltration membrane screening process, the pressure difference between the two sides of the membrane as the driving force, the ultrafiltration membrane as a filtration medium, under a certain pressure, when the original liquid flows through the membrane surface, the ultrafiltration membrane surface is densely covered with many tiny microporous only allows water and small molecules to pass through and become a permeate, and the volume of the original liquid is greater than the surface of the membrane microporous diameter of the material is retained in the membrane of the inlet side of the liquid to become a concentrated liquid, thus realizing the purification of the liquid, separation and concentration of the purpose. Thus, the purpose of purification, separation and concentration of the original liquid is realized. There are about 6 billion 0.01 micron microporous holes on the wall of each meter-long ultrafiltration membrane filament, and its pore size only allows water molecules, beneficial minerals and trace elements in water to pass through, while the volume of the smallest bacterium is above 0.02 micron, so the bacteria as well as colloid, rust, suspended solids, sediment, macromolecules and other organic matter which is much larger than the bacterial volume can be retained by the ultrafiltration membrane, thus realizing the purification process.

The formula is:

S inside = πdL×n

S outside = πDL×n

Which: S inside is the total internal surface area of the membrane filament, d is the inner diameter of the ultrafiltration membrane filament;

S outside is the total external surface area of the membrane filament, D is the outer diameter of the ultrafiltration membrane filament;

L is the length of ultrafiltration membrane filament;

n is the number of the roots of the membrane. the number of roots of the ultrafiltration membrane filament.

Introduction of hollow fiber UF membranes, internal and external pressure types

Polyacrylonitrile (PAN). Polyacrylonitrile, abbreviated as PAN, is obtained by free radical polymerization of acrylonitrile monomer. The acrylonitrile units in the macromolecular chain are connected in the way of joint-tail. Appearance is white powder, density is 1.14~1.15g/cm, soften and decompose when heated to 220~300℃.

Main applications

Polyacrylonitrile is mainly used in the manufacture of synthetic fibers (such as acrylic). Synthetic fibers imitated by polymers with more than 85% of acrylonitrile and other second and third monomers ****polymer. Chinese trade name for polyacrylonitrile fiber. Commonly known as artificial wool. DuPont in the United States in the 1940s developed successful pure polyacrylonitrile fiber (trade name Auron), because of the dyeing difficulties, easy to original fiber, has not been put into industrial production. Later, on the basis of improving the imitability of the polymer and the dyeing of the fiber, acrylic fiber was able to realize industrial production. There are different trade names in different countries, such as Auron, Acleron, Krylon, Zefflon in the U.S.A., Kautel in the U.K., Maurillon, Cashmere, Ixilan, Bethlon in Japan, etc. The density of Acrylic fiber is generally 1.5 mm. The density of acrylic fiber is generally 1.16~1.18g/cm3, and the standard moisture return rate is 1.0%~2.5%. The fiber is characterized by good fluffiness and warmth, soft handfeel, and good weather resistance and mildew and moth resistance. Mainly used as man-made fibers, commonly known as artificial wool; wool, knitted fabrics (pure or blended with wool) and woven fabrics, especially suitable for indoor decorative fabrics, such as curtains. In material science, it is often used to synthesize polyacrylonitrile as the base to synthesize multi-hollow materials, such as PAN-based activated carbon.

There are many materials that can be used to manufacture ultrafiltration, including: polyvinylidene fluoride (PVDF), polyethersulfone (PES), polypropylene (PP), polyethylene (PE), polysulfone (PS), polyacrylonitrile (PAN), polychloroethylene (PVC), etc. In the early 1990's, polyethersulfone was commercially used; and at the end of the 1990's, the better performance of PVDF began to be widely used in water treatment. In the late 1990s, the ultrafiltration of polyvinylidene fluoride (PVF) with better performance began to be widely used in water treatment industry. As a result, polyvinylidene fluoride and polyethersulfone have become the most widely used ultrafiltration membrane materials. Operating Pressure 225psi (1.55Mpa)

Test Fluid Temperature 770 F (250C)

Test Fluid Concentration 2000 mg/L (as NaCl)

Water Recovery 15% from Single Element

Test Fluid pH 7

Minimum Desalination 99.0% from Single Element

Minimum Transmission Volume 8,000 psi (1.55Mpa)

Minimum Water Recovery 8,000 psi (1.55Mpa) Minimum water throughput 8,200gpd (31.0m3/d)

Other features of the ultrafiltration membrane accessories are as follows:

1) The shell is made of impact-resistant ABS material, with a pressure-bearing capacity of more than 16KG, and the wall thickness is thickened by 1mm, which is able to withstand all kinds of pressure impacts that may arise from the water intake, ensuring that no rupture will occur under the impact water pressure, avoiding the membrane to be subjected to prolonged pressure during the use of the ultrafiltration membrane. In the process of using the long-term pressure, material creep caused by water leakage.

2)Each HUF90 membrane is loaded with 1400 membrane filaments, and the length is lengthened by 100mm, which increases the membrane area by 15%, and the effective membrane area is higher than that of any domestic product of the same specification. The effective membrane area is higher than that of any domestic product of the same specification, which improves the water production.

3) end cover for the hemisphere protruding structure, compared with the traditional end plane structure, so that the water in the end of the membrane filaments in the face of a more uniform distribution, and wall thickness of 1mm, to ensure that in the impact of water pressure does not break.

4)The bonding between the shell and the threaded sleeve is made of French imported glue, the bonding length is lengthened, and the connection gap is uniform. In the process of use will not appear leakage. Degumming phenomenon, and fully meet the health standards.

5)The connection thread between the end cap and the shell adopts serrated thread, which increases the torsion distance and load, and there will be no slippage and water leakage. Leakage phenomenon.

6)The effective area of the membrane is large, the water flux is large, the pure water flux is 1800 liters, which is much higher than the same specification products in China.

7)Pressure-resistant and leak-proof structure design ensures that the HUF90 ultrafiltration membrane will not leak, degumming, slippery teeth, storm glue and other phenomena.

Ultrafiltration membranes are divided into: inorganic and organic membranes according to the different membrane materials, and inorganic membranes are mainly ceramic and metal membranes.

Organic membrane

Organic membrane is mainly made of polymer materials, such as cellulose acetate, aromatic polyamide, polyethersulfone, polyvinylidene fluoride and so on. According to the different shapes of the membrane, it can be divided into flat membrane, tubular membrane, capillary membrane, hollow fiber membrane and so on. The membrane used in household water purifier on the market is basically hollow fiber membrane.

Inorganic membrane

Inorganic membrane, ceramic ultrafiltration membrane is more widely used in household water purifiers. Ceramic membrane long life, corrosion resistance, but the water has an earthy flavor, affecting the taste. At the same time, ceramic membrane is easy to clog, cleaning is not easy. Hollow fiber ultrafiltration membrane is widely used in the household water purification industry due to its high filling density, large effective membrane area, high pure water flux, simple operation and easy cleaning advantages.

In the case of constant water production per unit of membrane filament area, the larger the membrane area of the cartridge filling, the greater the total water production of the cartridge.

The formula is: S inside = πdL × nS outside = πDL × n

Which: S inside the total internal surface area of the membrane filament;

d for the inner diameter of the ultrafiltration membrane filament;

S outside the total external surface area of the membrane filament;

D for the ultrafiltration membrane filament outer diameter;

L for the length of the ultrafiltration membrane filament;

n for the number of ultrafiltration membrane filaments.

According to the shape of the membrane characteristics of ultrafiltration membranes can be divided into:

1) flat membrane;

2) tubular ultrafiltration membranes, pore size & gt; lOnm;

3) capillary ultrafiltration membranes, pore size O.50 ~ 10.00nm;

4) hollow fiber ultrafiltration membranes, pore size & lt; 0.5nm;

5) porous ultrafiltration membrane.

Hollow fiber ultrafiltration membrane

A ultrafiltration membrane consists of hundreds to thousands of tiny hollow fiber filaments, generally the hollow fiber membrane inner diameter of 0.6-6mm between the ultrafiltration membrane is called capillary ultrafiltration membranes, capillary ultrafiltration membranes because of the larger inner diameter, is not easy to be blocked by large particulate matter.