04 February 2006

Better Living Through . . . . Membranes?

Basically, membranes are a semi-permeable barrier. They're like a wall, except that gases, and even liquids, can seep through them. But--here's the key point--different molecules move through membranes at different rates. Membranes can therefore be used to sort things out, separating one type of molecule from another. Membranes have many uses on Earth, not only on Mars.

Here is an innovations-report about the discovery of a rubber-like membrane (by scientists at U of Texas, Austin), that retains hydrogen gas while allowing carbon dioxide gas to escape.

This member of a new family of membrane materials with superior gas-separating ability could lower the costs of purifying hydrogen for hydrogen-fueled vehicles. Hydrogen fuel cells are considered a leading alternative energy for running cars and other devices in the future. The membrane material could also replace an expensive step in current petrochemical processing, or reduce how much energy the step requires. The membrane was tested under conditions that mimic those routinely used by the petrochemical industry to refine petroleum components (crude oil and natural gas) for use.

"A significant amount of the hydrogen in use today goes into the refining industry to refine crude oil to produce gasoline or other products, so this membrane could lower refining costs," said Freeman, the Kenneth A. Kobe Professor in Chemical Engineering.

The membrane differs structurally and functionally from previous options, with a key advantage being its ability to permit hydrogen to remain compressed at high pressure. A compressed form of the light-weight gas is needed to process fossil fuels and for it to serve as a readily replaceable fuel for fuel cells.

Biological membranes perform an incredible number of vital functions for cells and sub-cellular components. Synthetic membranes are used in industrial and chemical processes for separation of liquids and gases.

The synthetic membrane recently discovered at UT Austin, will find a large number of important uses eventually. Reducing the costs of petroleum refining, and making hydrogen fuel cells more practical, are only two high impact uses for this membrane. It is easy to speculate that such membranes will be used for air recycling for anesthesia, undersea breathing uses, and possibly for air recycling in space. Those and many other uses will come when the membranes go into higher level production, and costs are lowered.

Nanotechnological membrane development is the next stage beyond mere chemical synthesis of membranes. With nanotech membranes, we may be able to approach the incredibly fine selectivity of biological membranes, while retaining the hardiness of non-living materials.
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