Hollow fiber membrane (Hollow fiber membrane) looks like a fiber with self-supporting membrane, a kind of asymmetric membrane, its dense layer can be located on the outer surface of the fiber (such as reverse osmosis membrane), but also can be located on the inner surface of the fiber (such as microfiltration membrane and ultrafiltration membrane). The wall of the hollow fiber membrane tube is covered with micropores, and the pore size can be expressed by the molecular weight of the trapped material, which can reach thousands to hundreds of thousands of molecular weight. Hollow fiber membrane module was first developed by The Dow Chemical Company in the United States using cellulose acetate (CA) as raw material. Because polyacrylonitrile (PAN), polypropylene (PP), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polysulfone (PS), polyethersulfone (PES) and other materials have good acid and alkaline resistance, microbial erosion resistance, oxidation resistance and good mechanical strength, they are now widely used in the manufacture of hollow fiber membranes. The membrane diameter of the hollow fiber membrane assembly is 0.2-2.5 mm, and the ratio of inner to outer diameter is 2-4, which is much thinner than the capillary membrane (the diameter of the membrane tube is about 3-6 mm) and the tubular membrane (the diameter of the membrane tube is 6-25 mm).
Hollow fiber membrane separation adopts dynamic "cross-flow filtration" mode: That is, driven by pressure, the solution flows at a certain speed on the inner membrane surface of the membrane tube, and small-sized substances such as water, small organic molecules and inorganic ions in the solution can be transferred to the other side of the membrane through the micropores on the hollow fiber wall, while large-sized substances such as bacteria, suspended solids, colloids, particles and organic macromolecules in the solution cannot be trapped through the hollow fiber wall. Thus, the purpose of separation and purification of components in the solution is achieved.
Hollow fiber membrane is mainly used in mineral water purification, production and living water purification, pharmaceutical purification, juice concentration, water treatment and recycling, etc. Pharmaceutical, chemical, construction, textile, papermaking, petrochemical and other industries. In the pharmaceutical and bioengineering industry, it is mainly used in:
1. antibiotics, vitamins, organic acids, amino acids, enzyme preparations and other fermentation liquid filtration and clarification (bacteria and protein)
2. Filtration and removal of cell debris during the preparation of protein and polysaccharide;
3. Clarification, sterilization and filtration of proprietary Chinese medicine and health products oral liquid;
4. Purification and concentration of biological products (polypeptide, bone peptide, thymosin, bovine serum protein, transfer factor);
5. biological solution desalting concentration, clarification and sterilization, protein elimination, cell collection and other separation processes