Microwaving Is The Best Method To Clean Nanotubes, According to Researchers
Scientists have discovered that, of all the advanced methods used today, microwaving the nanotubes is the most useful way of removing impurities.
Carbon nanotubes come in multiple forms and have a variety of applications. For some of these applications though, they have to be pure and free of any residue that remains from their formation. Cleaning nanotubes is, however, complicated as well as costly.
Recently, researchers at Rice University in Houston, Texas have discovered that impurities found in nanotubes can be easily removed if the tubes are put in a standard kitchen microwave first, before a high-temperature chlorine is used to eliminate almost all of the extraneous particles.
Unlike other methods, chlorine has the advantage of not damaging the nanotubes. But, due to its inability to react with particles encapsulated by carbon atoms, many of the residual metal particles are left on or inside the nanotubes after they are grown, and can can significantly impact the their properties.
According to the researchers, if the nanotubes are first put into a 1000 W microwave oven, it becomes much easier to get metal particles to react with chlorine.
The technique worked well when removing particles on the surface of nanotubes, but not for those that were within their walls. Luckily, these particles do not pose as great an issue for many applications, said professor Andrew Barron at Rice.
“The chlorine method has the advantage of not damaging the nanotubes, unlike other methods,” said professor Andrew Barron. “Unfortunately, many of the residual catalyst particles are surrounded by a carbon layer that stops the chlorine from reacting, and this is a problem for making high-purity carbon nanotubes.”
The research could prove useful for sensitive practices like drug delivery or solar panels, which require nanotubes to be as pristine as possible.
Source: Rice University