Ultrafiltration (UF) membranes have found widespread use in the food and biotechnology industries. UF has been applied in the processing of normal and transgenic milk, cheese and eggs, whey and potato protein recovery, the clarification of juices and wine, the recovery of proteins from animal blood, and the purification of water. UF is also used in the biotechnology industry for the recovery of biological products through such steps as cell broth clarification, cell harvesting, concentration or diafiltration of protein solutions prior to separation, and final concentration.
A major obstacle in the incorporation of membrane processes into industrial operations is the problem of flux decline due to fouling during the ultrafiltration of biological products such as proteins. Fouling not only decreases membrane permeability which reduces productivity due to longer filtration times, but also shortens membrane life due to the harsh chemicals necessary for cleaning. Furthermore, fouling can alter membrane selectivity and lead to significant product loss through denaturation. This technology provides an improved UF membrane product having a porous body with high density grafting of short chain vinyl monomers on its surface. Thus, the membrane exhibits low protein fouling, and maintains a greater fraction of the original membrane permeability and retention properties after modification.