Technology


 

Metalmembranes has developed and patented a method for making membranes that marry many of the benefits of ceramic and polymeric membrane technologies. Like classic ceramic membranes, Metalmembranes technology offers robust surfaces – yet higher flux. Like polymeric membranes, Metalmembranes technology offers a more low-cost solution – yet better robustness and potentially less fouling. 

Metalmembranes are produced in the following way:

- plasma electrolytic oxidation (PEO) to create a thin porous crystalline metal-oxide on the front side of an exposed metal surface. Suitable metals for PEO are aluminum or titanium.

 - electrochemical machining (ECM) to selectively remove the back side of the metal surface, the underlying metal is completely removed such that only the thin metal oxide layer remains – upheld by the surrounding metal that was not etched away. Thus, custom wells/channels can be created that utilize the porous metal-oxide membrane to filter any medium of interest. 

The PEO process enables pore-size tailoring while the ECM process enables well/channel customization.

- module preparation to support the ceramic layer by a rigid support allowing for filtration at high pressures (up to 10 bar) through a thin porous layer of 50 micron, thereby allowing for extreme high flows through the membrane. The roughness of the membrane on the permeate side is sufficient to act as a permeate spacer allowing water to flow in-between the porous layer and the support plate.

Benefits

  • High flux: Strong peripheral material support allows membranes to support high pressure levels, leading to high flow rates
  • Robust operation: Membrane structure is inherently more robust than polymeric counterparts (e.g., chemical and temperature resistance, mechanical stability, etc.)
  • Low fouling: Material structure as well as novel designs minimize fouling and facilitate membrane cleaning when fouling eventually occurs
  • Custom selectivity: Tailoring pore size allows application-specific customization
  • Design flexibility: The ability to tailor multiple product features (e.g., pore size, membrane thickness, membrane material, well/channel size) facilitates creativity for application developers and filtration-system designers
 


Properties
 

Material

Aluminum

Titanium

Thickness membrane  

10-150 micron*

10-150 micron*

Pore size

100 nm - 150 nm

15 nm

Chemical composition

Al2O3

TiO2

Pressure

10 bar

10 bar

Clean water flux

4.000 l/(m2 h bar)  

1.000 l/(m2 h bar)

pH range

4 – 9

3 – 12

Temperature range

< 300 °C

< 500 °C

* Thickness of the membrane can be tuned