Ultrafiltration membrane is a kind of microporous membranes which has a rated pore diameter of 0.001micron – 0.02micron. Imposing appropriate pressure on one side of membrane, it can sift out the solute molecules which are smaller than pore diameter. The ultrafiltration membrane can separate the particles which molecular weight is greater than 500 Dalton and the diameter is greater than 2-20 nanometers. The ultrafiltration membrane is one of the earliest developed polymeric membranes. The ultrafiltration devices have achieved the industrialization in 60 years.
According to the material, ultrafiltration membrane can divide into inorganic membrane and organic membrane. The inorganic membrane of ultrafiltration membrane has two main types: ceramic membrane and metal membrane. Ceramic membrane has a long use life and good corrosion resistance, but it is easily to blocked and is difficult to clean.
The organic membrane of ultrafiltration membrane is usually made of high molecular material, like aromatic polyamide, PES, PVDF and so on. According to the size of membrane, the organic membrane can divide into flat membrane, tubular membrane and hollow fiber membrane and so on. The household purifiers on market at present are applying hollow fiber membrane. Hollow fiber membrane has many advantages like large packed density, large effective membrane area, high pure water flux, simple operation and cleans. It is widely used household water purification industry.