Facile Fabrication of Superior Nanofiltration Membranes Containing Carbon Nanotubes

Membranes in successful separation applications possess simultaneously reasonable flux and considerable selectivity. Extensive efforts to improve both the flux and selectivity continue. Carbon nanotubes (CNTs) hold a special promise to radically enhance the transport rates of solvents such as water through the inner core of CNTs as demonstrated in 2006 by Holt et al. for double-walled carbon nanotubes (DWNTs). This group developed a vertically aligned array of DWNTs on a silicon chip by a combination of chemical vapor deposition, ion milling and reactive ion etching ending up with a membrane containing CNTs open at both ends. The resulting membrane using the inner core of the CNT for transport however had a low CNT-based porosity of only around 0.5%. Such a membrane fabrication procedure is demanding. Other CNT-based membranes reported in recent research require a demanding fabrication procedure as well. Using conventional polymerization methodology we have developed a facile procedure for fabricating highly productive solvent-resistant nanofiltartion membranes conatining CNTs. Results for flat membranes will be presented. These membranes demonstrate an order of magnitude increase in solvent/water flux in methanol-based and water-based systems. Membrane performances demonstrate high rejections of test solutes brilliant blue R (MW 826) and Safranin O(MW 351) from methanol and aqueous solutions. Results of performance variation with a variety of parameters including CNT length, CNT weight fraction and applied pressure difference will be reported. The potential basis for performance enhancement will be discussed.