In the home, ultrasonic humidifiers are used to raise humidity, reduce static electricity and ease discomfort from the common cold or cough. In the lab, chemists at the University of Illinois at Urbana-Champaign are using the devices to make complex nanocomposite materials that could prove useful as catalysts in applications ranging from refining petroleum to making pharmaceuticals. The procedure is both simple and efficient.
"Normally, the chemical effects of ultrasound (called sonochemistry) are due to intense heating of small gas bubbles as they collapse in an otherwise cold liquid," said Kenneth S. Suslick, a William H. and Janet Lycan Professor of Chemistry at Illinois. "But in this case we are looking at using ultrasound to make very small liquid droplets and heating them while they are separated from one another in a heated gas. It's the inverse of what we do sonochemically."
To create their novel nanocomposite materials, Suslick, graduate student Won Hyuk Suh and research fellow Yuri Didenko start with a solution of chemical reactants and surface-stabilizing surfactants. The solution is turned into a mist using a high-frequency ultrasound generator an ordinary household ultrasonic humidifier the researchers purchased at a local discount store.
The resulting droplets are carried by a gas stream into a furnace, where the solvent evaporates and the chemicals coalesce into inorganic-organic composite materials nanometers in size. The particles are carried to a second, hotter furnace, where the organic part burns away, leaving behind porous inorganic nanospheres. These nanospheres are then trapped in a liquid and collected by ce
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Contact: James E. Kloeppel
kloeppel@uiuc.edu
217-244-1073
University of Illinois at Urbana-Champaign
28-Mar-2004