Recent work by the Lawrence Livermore National Laboratory brought yet another possible use for carbon nanotubes to our attention in the form of filtration systems. Immediate applications could be desalinization and other forms of water filtration. The intricate properties of the interactions between carbon nanotubes and water molecules make the filters very efficient.

Carbon itself, in forms such as nanotubes or graphene (sheets of carbon just one layer of atoms thick), is actually hydrophobic. That is to say that it actually repels water, giving it no surface to cling to. So why do these nanotube filters outperform conventional filtration systems?

Researchers at the University of North Carolina at Chapel Hill have been looking into these interactions using rolled graphene nanotubes. More specifically, they have been examining how water flows through these tubes which should be hydrophobic.

What they found was that at room temperature, water only stubbornly moved through the 1.4 nanometer diameter tubes. However, when they reduced the temperature of the nanotubes to eight degrees centigrade, water moved easily through. Yue Wu, Ph.D., leader of the study, explains that the results show that it is possible for water to assume different properties and structures based on temperature and the size and shape of the confining structure at the nanoscale.

Far from simply showing these changes, the research may have several immediate real world applications. As well as making desalinization filters like LLNL's more efficient, it could apply to simple activated charcoal filters like the ones found in homes. Gas masks and other permeable membranes could benefit from the study as understanding how temperature affects permeability would allow better systems to be designed, as well as brings the potential of temperature controlled flow control in these situations.