Ionic and Molecular Transport Through Graphene Membranes
New membrane materials have the potential to address some of the persistent challenges in water purification to improve the flux of water, selectivity to ions or contaminants, and fouling resistance. With its atomistic thickness and the ability to sustain nanometer-scale holes, graphene promises significant enhancement in the flux of water while offering potentially novel transport properties. In this work, the transport of ions and molecules through a single layer of graphene were measured as a first step towards realizing practical graphene membranes. Graphene grown by chemical vapor deposition (CVD) was transferred to a porous polycarbonate support membrane, and the diffusion of different salts and molecules was examined. While pressure-driven flow measurements revealed that the graphene covered the polycarbonate support membrane, diffusion experiments showed that it was permeable to salts, but not to larger molecules. This behavior was attributed to intrinsic defects in graphene in the 1–15 nm size range.
KeywordsReverse Osmosis Scan Transmission Electron Microscopy Membrane Material Water Desalination Graphene Lattice
The author thanks the organizers and NATO for the opportunity to attend the NATO Advanced Research Workshop on Alternative Water Resources in Arid Areas by Retrieving Water from Secondary Sources held at the Daniel Dead Sea Hotel, Israel, from May 7–11, 2012. The author would like to thank students and collaborators involved in the research, especially Sean O’Hern. The work discussed here was funded by King Fahd University of Petroleum and Minerals in Dhahran, Saudi Arabia through the Center for Clean Water and Clean Energy at MIT and KFUPM under project number R10-CW-09. Part of the research was performed at ORNL’s Shared Research Equipment (ShaRE) User Program sponsored by DOE, the Center for Nanoscale Systems (CNS) at Harvard, and the Center for Materials Science and Engineering at MIT.