What did scientists discover?
When molecules are forced to pass through narrow holes in membranes, they must move one-by-one in single file. When this “No Passing!” rule is in effect, researchers have recently made the surprising discovery that mixing two gases can lead to faster motion of some of the molecules through the narrow holes.
Why is this important?
Many technologies of great importance rely on small holes in membranes to pass only certain molecules:
- Pure water molecules to remove pollutants from fresh water.
- Pure water molecules for desalinization of salt water.
- Hydrogen and methane for fuel cells. Fuel cells are “super batteries” that store energy in chemical bonds … and thus can store much more energy than regular batteries.
These processes are poorly understood:
- The reasons the holes plug with unwanted molecules, reducing their effectiveness, shortening their lifetime, and driving up costs.
- The fundamental mystery of the faster motion of some molecules through smaller holes when they are mixed with other molecules.
Who did the research?
The team, all from the University of Florida, included: Akshita R. Dutta, Poorvajan Sekar, Muslim Dvoyashkin, Clifford R. Bowers, Kirk J. Ziegler, and Sergey Vasenkov.
Why did they need the MagLab?
Because these holes are so small that they literally can only pass one molecule at a time, they are too small to be seen with a microscope. Magnetic fields act as a “super microscope” by measuring the motion of the atoms using a technique that resembles Magnetic Resonance Imaging (MRI). The MagLab, home of the highest magnetic fields and highest-magnetic-field MRI techniques, provides researchers unique capabilities to collect sufficiently clear data to measure the speed of molecules as they move single-file through the narrow holes that are made available by the most modern hydrogen-porous membranes and carbon nanotubes.
Details for scientists
- View or download the expert-level Science Highlight, Single-File Diffusion of Mixed and Pure Gases by High Field NMR
- Read the full-length publication, Relationship between Single-File Diffusion of Mixed and Pure Gases in Dipeptide Nanochannels by High Field Diffusion NMR, in Chemical Communications.
This research was funded by the following grants: G.S. Boebinger (NSF DMR-0654118, DMR-1157490), K. J. Ziegler and S. Vasenkov (ACS PRF, PRF#53140-ND10), C.R. Bowers and S. Vasenkov (NSF, CHE-0957641), S. Vasenkov (NSF, CBET-0951812, HWK Senior Fellowship)
For more information, contact Joanna Long.