Enhanced Mass Transport in Carbon Nanotubes
|Researchers experimentally demonstrate fast mass transport through a specially fabricated, sub-2-nanometer carbon nanotube filter.|
Reviewed by Dr. Haitao Liu, Columbia University
Holt, J.K., Park, H.G., Wang, Y., Staderman, M., Artyukhin, A.B., Grigoropolous, C.P., Noy, A., and Bakajin, O., "Fast Mass Transport Through Sub-2-Nanometer Carbon Nanotubes" Science 312 (2006)1034-1037. DOI: 10.1126/science.1126298
Theoreticians have long believed that the carbon nanotube is the perfect water pipe. This might sound counterintuitive, especially considering that the surface of a carbon nanotube is hydrophobic. In fact, the graphene surface of the carbon nanotube is so flat that a water molecule experiences almost no friction as it passes through the nanotube. Numerical simulations have predicted mass transport in carbon nanotubes at significantly faster rates than those of of classical theory.
The authors found that the permeability of the carbon nanotube filter was orders of magnitude higher than the conventional polycarbonate filter. More significantly, they showed that the measured air flow rate was several hundred times higher than what classical theory would predict. In the case of water transport, the enhancement was several thousand times. The enhanced water flux, however, compared well with what predicted by the molecular dynamics simulations, which takes into account of the flat, almost frictionless surface of the carbon nanotube interior.
Image from Holt, J.K., et.al., "Fast Mass Transport through Sub-2-Nanometer Carbon Nanotubes," Science 312 (2006) 1034-1037. Reprinted with permission from AAAS.
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