Carbon nanotube hollow fiber membranes: High-throughput fabrication, structural control and electrochemically improved selectivity

A simple approach to high throughput fabrication of length-unlimited, neat carbon nanotube (CNT) hollow fiber membranes based on wet-spinning technology is presented. The prepared CNT membranes exhibit uniform hollow fiber configuration, good electrical conductivity and controllable attributes (for example, thicknesses, structures and pore sizes). Specifically, the CNT hollow fiber membranes with three-dimensional macroporous structure in their cross sections can support a water flux of 12000 +/- 1500 L m(-2) h(-1) bar(-1) which is 6 times higher than that of polymeric membranes with the similar pore size of about 100 nm, 10 times and 2 times higher than that of commercial Al2O3 ceramic membranes (pore size of 1000 nm) and polycarbonate membranes (pore size of 200 nm), respectively. Experimental measurements indicate their ultrahigh porosity of 95 +/- 3% and hydrophilicity derived from H2SO4/HNO3 treatment of CNTs for well dispersion in solvent mainly account for the high permeability. Benefiting from their good electrical conductivity, the CNT membranes demonstrate the interesting electricity-induced improved selectivity (rejection ability) for nanoparticles, which is mainly attributed to the electrostatic interaction, preventing their penetrating the CNT membranes. The distinctive function of CNT membranes is highly expected to contribute to various important areas of application, such as water purification and biomolecule separation. (C) 2015 Elsevier B.V. All rights reserved.