diafiltraation

Diafiltration is a membrane filtration process used to remove or exchange the solvent in a solution or to concentrate a solution. It is a type of cross-flow filtration, meaning that the feed stream flows tangentially across the surface of the membrane, while the permeate (the solvent that passes through the membrane) is removed. This cross-flow action helps to prevent the membrane from becoming fouled, which can reduce its efficiency over time.

In diafiltration, a fresh solvent is continuously added to the retentate (the solution that does not pass through the membrane) while the permeate is removed. This process effectively dilutes and washes away unwanted components from the retentate, or allows for the exchange of the original solvent for a new one. The key difference between diafiltration and simple concentration by filtration is the addition of fresh solvent.

Diafiltration is widely used in various industries, including pharmaceuticals, biotechnology, food and beverage, and water treatment. In the pharmaceutical industry, it is employed for buffer exchange, desalting, and purification of proteins and other biomolecules. In the food industry, it can be used for lactose removal from whey or for concentrating fruit juices. Water treatment applications include the removal of salts and other dissolved impurities.

The effectiveness of diafiltration depends on several factors, including the membrane material and pore size, the operating pressure, the flow rate, and the volume of fresh solvent added. The process can be operated in batch or continuous modes, depending on the application and scale. The goal is to achieve a desired concentration of the target solute while effectively removing or exchanging the solvent.