Zeolites: Nature's Molecular Colander

Zeolites are porous, sieve-like minerals used in purifiers, filters and other devices. But little is still known about how they form and how to make them in the laboratory.

Now, using some of the most advanced microscopes, a team of scientists has uncovered new details for the step-by-step evolution of zeolites from when they're a molecular soup to the carefully engineered crystals that they become.

With this knowledge, scientists could create zeolites with precisely the crystal sizes and shapes demanded by molecule-specific applications such as chemical sensing.

Zeolites are familiar to most people as the white crystals in aquarium filters, or the ion-exchanging workhorses in advanced detergents. But their real economic impact is behind the scenes, where they are critical for extracting various chemical components out of petroleum and its byproducts on an industrial scale.

They trap and remove specific chemicals, which makes it easier for companies to purify the chemicals they want. So the challenge for researchers is to tailor a zeolite for each application that traps just the right set of chemicals.

The ultimate goal is to control the structure, size and shape of the crystals well enough for zeolites to serve as sponges for hydrogen in fuel tanks, channels in next-generation sensors and separation membranes for chemical manufacturing.

The study, conducted by Tracy Davis of University of Minnesota and colleagues, is detailed in the Apr. 17, 2006, online in Nature Materials.

--Sara Goudarzi

·          Amazing Images: Science & Nature Photos from Our Readers

Credit: Michael Tsapatsis, University of Minnesota