Diafiltration
The diafiltration is a membrane-technical method, in which the solvent and, depending on the application, a part of the ingredients of a solution or a suspension to be replaced. This process is often used after a classic tangential flow filtration , as it hardly differs from its technical requirements.
Working principle
The original whose solvent is to be changed is circulated from the original container. By regulating the flow after the membrane module, a transmembrane pressure (TMP) is set, which acts as the driving force in the diafiltration. The pore size of the membrane is chosen so that the molecules to be removed can penetrate the membrane. Since the system is operated as a closed system, the removal of the permeate leads to the flow of the exchange solvent, whereby the circulating volume remains constant during the diafiltration. As soon as the same volume that was originally submitted has left the system once as permeate and has been replaced by new solvent, a so-called diafiltration volume has been reached.
Applications
Microfiltration
Suspensions that have been contaminated during production are passed through a microfiltration membrane in tangential flow mode. The template ( Feed ) is filled to a pure liquid during the process with the same amount, as will be separated during the filtration. In this way the suspension is cleaned without the disadvantages of an increase in viscosity . The production of high-purity substances is a typical area of application for this process.
Ultrafiltration
In the case of ultrafiltration applications , solvents are exchanged in solutions in the same way, higher molecular components are separated from lower molecular ones, or their composition is changed.
Nanofiltration
In nanofiltration applications , smaller organic molecules can be represented in a highly pure manner. This process is important in the chemical and food industries.
Hemodiafiltration
In hemodiafiltration , hemodialysis and hemofiltration are combined. This combines the pressure-driven and the concentration-driven properties of both processes.
literature
- Herbert Walter Irmler: Dynamic filtration with ceramic membranes . Vulkan, 2001, ISBN 3-8027-2840-8 .