E. Marand, A. Surapathi, W.F. Chan, H. Chen, D. Chen, X. Shao, J.K. Johnson
Virginia Polytechnic Institute and State University, US
desalination, membranes, carbon nanotubes
We have developed asymmetric carbon nanotube/polyamide membranes for desalination applications. The carbon nanotubes are functionalized with zwitterionic groups that control the rejection of anionic species, while permitting the transport of water. Water flux measurements demonstrate that the water flux in the CNT-nanocomposite membranes is orders of magnitude higher than that observed in an asymmetric polyamide membrane, with salt rejection maintained above 80%. We have also conducted corresponding atomistic simulations of the water and ionic transport. We used non-equilibrium molecular dynamics to model the transport of fluids through functionalized carbon nanotubes, including entrance effects. We have shown that zwitterions are able to completely block the flow of salt ions while still allowing water flux through the membrane.