Ultrafiltration Technology and Its Characteristics

Ultrafiltration (UF) is also a membrane separation process driven by pressure difference, and is generally considered a sieve-based separation process. Driven by the pressure difference, the solvent and small solute particles in the feed solution permeate through the membrane from the high-pressure feed side to the low-pressure side. The resulting liquid is generally called the filtrate or permeate, while larger particles are retained by the membrane, increasing their concentration in the filtrate, thus achieving the purpose of purification, separation, and concentration. The water treatment center pioneered the successful development of this technology in China in the 1980s.

Characteristics of Ultrafiltration Technology:

Early ultrafiltration membranes used cellulose acetate membrane materials. Later, polysulfone, polyethersulfone, polyacrylonitrile, polyvinyl chloride, polyvinylidene fluoride, vinyl chloride alcohol, and inorganic membrane materials were also used. The membrane pore size is approximately 0.002–0.1 μm, and the molecular weight cutoff is approximately 500–500,000. Its operating pressure is around 0.07–0.7 MPa.

The ultrafiltration process has the following characteristics:

(1) No phase change occurs during the process, and it can be carried out at room temperature and low pressure, thus consuming little energy;

(2) No qualitative change occurs in the substances during the concentration and separation process, making it suitable for the treatment of heat-sensitive substances;

(3) It can separate substances of different molecular weights into fractions;

(4) No impurities are shed from the ultrafiltration membrane during use, ensuring the purity of the ultrafiltrate.