UF is one of the pressure-driven membrane separation technology. Macromolecules and small molecules for the purpose of separation, membrane pore size between 20-1000A °. Hollow fiber ultrafilter (film) has dissolved the unit is filled with high-density, small footprint advantages. In the ultrafiltration process, the aqueous solution at a pressure driven flows through the membrane surface, smaller than the membrane pore solvent (water) and small solutes permeable membrane, become cleaning fluid (liquid filtration), larger than the membrane pores solute and solute Group are retained, with the water discharge, a reduction was dissolved. Ultrafiltration is a dynamic filtration, separation is accomplished in a flow state. Solute is deposited on the membrane surface with only a limited, ultrafiltration rate reduction to a certain extent and tends to balance, and can be restored by washing.
Ultrafiltration is a separation technique plus film, that is, under a certain pressure, so that the solvent and small solutes through the membrane a certain special aperture, leaving the macromolecular solute impermeable to stay in side of the membrane, so that the macromolecules has been purified fraction.
Advantages ultrafiltration technique is simple, low cost, without adding any chemical reagents, especially mild experimental conditions of ultrafiltration, evaporation, freeze-drying phase is unchanged, and does not cause the temperature, the change in p H , it is possible to prevent the denaturation of biological macromolecules, inactivation and autolysis. In the preparation techniques of biological macromolecules, biological macromolecules ultrafiltration mainly for desalting, dehydration and concentration and the like. Ultrafiltration also has some limitations, it can not directly get dry powder formulations. For protein solution, typically only get 10 to 50% concentration.