Preparation and Transport Performances of High-Density, Aligned Carbon Nanotube Membranes

We report a simple and effective method for the preparation of high-density and aligned carbon nanotube (CNT) membranes. The CNT arrays were prepared by water-assisted chemical vapor deposition (CVD) and were subsequently pushed over and stacked into dense membranes by mechanical rolling. It was demonstrated that various gases and liquids, including H-2, He, N-2, O-2, Ar, water, ethanol, hexane, and kerosene, could effectively pass through the aligned carbon nanotube membranes. The membranes exhibited different selections on different gases, indicating that there was a separation potential for the gas mixtures. The selectivities (H-2 relative to other gases) of H-2/He, H-2/N-2, H-2/O-2, and H-2/Ar were found to be lower than that of the ideal Knudsen model. For pure water, the permeability was measured to be 3.23 +/- 0.05 ml center dot min(-1)center dot cm(-2) at 1 atm, indicating that the CNT membranes were promising for applications in liquid filtration and separation.