Liquid filtration, meaning the separation of substances and solids from liquids, is carried out in many branches and using different processes. Ceramic membranes are being used increasingly often to improve the filter performance. In cross-flow filtration, CeramTec’s ceramic membrane carriers score points, not just for advantages such as their high mechanical, chemical and thermal resistance – thanks to their geometry, they also achieve the current maximum filtration performance using this process and thus help to save costs.
Ceramic membranes for cross-flow filtration
Cross-flow filtration is a filtration process where a suspension is pumped through porous tubes, so-called membranes, and the liquid which is filtered out, the permeate, is drawn out transversely to the direction of flow. Unlike cake filtration, the formation of a filter cake is prevented here.
For cross-flow filtration, CeramTec has specific multi-channel tubes made from aluminum oxide (Al2O3) on offer as carrier tubes where the application-related separation layer made up of aluminum oxide, titanium oxide or zirconium oxide is applied by the customer. The tubes are designed as ceramic membranes for mechanical separation processes: nano, ultra and microfiltration. These filtration processes are used, for example, in the food sector, pharmacy, chemical industry as well as in electroplating, environmental and biological technology.
Influential factors on the performance of the ceramic filters
Ceramic membrane carriers are available in various geometries for filtration. As well as different lengths, the number of channels and their diameter plays a crucial role in determining the efficiency of the filter performance. Longer carrier tubes have a greater surface area for filtration. Porous ceramic membrane tubes from CeramTec are therefore available up to a length of 1.5 meters.
The typical tube systems are between 1 meter and 1.5 meters, typical external diameters range from 10 millimeters to 52 millimeters and typical channel diameters are between 2 millimeters and 16 millimeters.
To go beyond the limits of the current possibilities in liquid filtration for customers, CeramTec is constantly developing the geometry and materials according to the market requirements. The current goal is to further increase the number of channels.
“The longer the tubes are, the less tubing and periphery is required to achieve the same filter performance. The same applies for the number of channels: the more channels, the greater the filter surface and the more efficient the filter system.”
Stephanie Neuberger, Account Manager
Advantages of ceramic membranes over other materials
Membranes made from technical ceramic have the following advantages when compared with polymer membranes or sintered metal. These advantages make them especially suitable for filtration processes under pressure or at high temperatures:
- Better mechanical stability
- High thermal resistance
- High resistance against aggressive media such as acids or alkalis
- They are highly inert
- They have a high permeate flow rate
- They can be backflushed easily to remove deposits on the surface
Further properties of the CeramTec Al2O3 material
- Average pore channel diameter of approx. 8 micrometers
- 28 percent porosity