Nanoparticles may be small, but they sure ain’t cheap - ounce for ounce some of them are more precious than gold. Which is why scientists are seeking better ways to recover, recycle, and reuse the tiny particles that are barely 1/50,000th the width of a human hair. A new method to recover these valuable specks using a special type of microemulsion may make such recovery efforts easier and speed the application of nanotechnology in a variety of fields.

In laboratory tests Julian Eastoe and colleagues suspended cadmium and zinc nanoparticles in the microemulsion - a mixture of oil and water. They showed how the oil and water in the microemulsion separated into two layers when heated. One layer contained nanoparticles that could be recovered and the other contained none. The separation process is reversible and the recovered particles retain their shape and chemical properties, which is crucial for their reuse, the scientists note.

The scientists that without such technology, manufacturing processes that take advantage of nanoparticles’ unusual properties might be prohibitively expensive. The development could speed application of nanotechnology in new generations of solar cells, flexible electronic displays, and other products as well as applications in cleanup and purification technologies.

Until now these applications have not been investigated because classical approaches recovering and recycling nanoparticles, such as ultracentrifugation, solvent evaporation, the addition of antisolvent CO2, and temperature control, are especially difficult because they tend to form complex, hard-to-separate mixtures with other substances.

The study, “Recovery of Nanoparticles Made Easy,” appears in ACS’ bi-weekly journal, Langmuir.