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Membranes and Their Uses

Photo of a MembraneWhat is a membrane?

A membrane is a device that selectively permits the separation of one or more materials from a liquid or gas.

IMTL’s membranes can be designed to use any of the passive membrane transport mechanisms
Photo of the Passive Membrane Transport Mechanisms

  • Molecular Sieving
  • Surface Diffusion
  • Knudsen Diffusion
  • Capillary Condensation

Advantages of Inorganic Membranes

Inorganic membranes are versatile. They can operate at elevated temperatures, with metal membranes stable at temperatures ranging from 500-800º C and with many ceramic membranes usable at over 1000º C. They are also much more resistant to chemical attack. Because of the wide variety of materials that may be used in the fabrication of our inorganic membranes, resistance to corrosive liquids and gases, even at elevated temperatures, can be realized. Inorganic membranes compete with organic membranes for commercial use. In many of the harsh operational environments listed above, organic membranes will not perform well, or will not survive at all. For these environments, only inorganic membranes offer needed solutions.

Uses of IMTL Porous Inorganic Membranes

Through their versatility, IMTL inorganic membranes can prove a benefit to

The oil and petrochemical industry

  • reducing the cost of hydrogen separation and recovery associated with oil refining and other processes.
  • reducing petroleum production costs by capturing reusable by-products.

Fossil fuel energy producers

  • lowering the cost and improving the efficiency of coal gasification.
  • economically recovering CO2 and other by-products of fossil fuel combustion to help reduce greenhouse gas emissions.
  • capturing iron oxides and other undesirable fossil fuel combustion by-products found in stack emissions.

Natural gas energy producers

  • increasing natural gas reserves by removing excess carbon dioxide, nitrogen, and moisture from natural gas wells.

The pulp and paper manufacturing industry

  • recovering fiber normally lost in the effluent.
  • recovering valuable chemicals for reuse and reducing the amount of chemicals released to the environment.
  • combining the uses above to convert a traditional paper factory to an almost self-contained process by separating chemicals and wastes from process water and recycling these valuable chemicals and now-clean water back into the processing stream.

Water cleanup/purification applications

  • producing potable and process grade water for industry and municipalities from surface and waste water, brackish water, sea water, brine water etc., using an inorganic reverse osmosis (RO) membrane with a very long lifetime. Inorganic RO membranes are resistant to chlorine and other disinfectants and can withstand steam treatments making them less vulnerable to bio-fouling.

Other applications, such as new advanced batteries and fuel cells

In most applications where energy savings will be realized due to the efficiency and performance of our membranes compared to other membranes or compared to competing separation processes that do not use membranes.

The Ability to Tailor Membrane and Filter Properties to the Broad Range of Filtration Needs is Achieved by Layering Practices

IMTL's membranes offer precise control of pore size with a high permeance and a low pressure drop. This is accomplished by carefully selecting the number of layers, the pore size of the layers, and the materials of construction to produce a product that will accomplish the desired separation.

Photo of the Critical Separation Layer Critical Separation Layer(s)

Pore Size: 4-50 angstroms
Thickness: single or multiple thin layers
Materials: Oxides
Uses: RO, nanofiltration & molecular sieving
Primary Layer

Pore Size: 0.005-0.5 µm
Thickness: 1-20 µm
Materials: oxides, carbides, nitrides, metals, metal alloys, and carbon
Uses: Ultrafiltration & microfiltration
Porous Support/Substrate

Pore Size: 0.5-50 µm
Thickness: >400 µm
Materials: Metals, metal alloys, oxides, carbides, nitrides, intermetallics
Uses: Depth filter & surface-cake filter

If a separation requires the removal of 10 µm particles, the final product may be a monolithic tube made from materials compatible with target process conditions that you specify. This tube can be fabricated with walls as thin as 400 µm (0.016 inches) for high permeance or up to 0.1 inches thick if additional strength is required.

If the separation requires much smaller pores, a layer or multiple layers may be used in conjunction with the porous support tube. The advantage of multiple layers is that the final separation layer can be made very thin, which yields a membrane with maximum permeance. Other surface treatments may be required for further reduction in pore size or for control of surface chemistry.  

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Information Owner: Brian L. Bischoff - Oak Ridge National Laboratory
Phone: 865-241-3172 - Email: zbx@ornl.gov
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Last modified 10.09.02 (carlson)

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