title: Scalable Graphene-Based Membranes for Ionic Sieving with Ultrahigh Charge Selectivity.
abstract: Nanostructured graphene-oxide (GO) laminate membranes, exhibiting ultrahigh water flux, are excellent candidates for next generation nanofiltration and desalination membranes, provided the ionic rejection could be further increased without compromising the water flux. Using microscopic drift-diffusion experiments, we demonstrated the ultrahigh charge selectivity for GO membranes, with more than order of magnitude difference in the permeabilities of cationic and anionic species of equivalent hydration radii. Measuring diffusion of a wide range of ions of different size and charge, we were able to clearly disentangle different physical mechanisms contributing to the ionic sieving in GO membranes: electrostatic repulsion between ions and charged chemical groups; and the compression of the ionic hydration shell within the membrane's nanochannels, following the activated behavior. The charge-selectivity allows us to rationally design membranes with increased ionic rejection and opens up the field of ion exchange and electrodialysis to the GO membranes.
authors.affiliation: Centre for Advanced 2D Materials, National University of Singapore , Singapore 117542.
authors.forename: Seunghyun
authors.initials: S
authors.lastname: Hong
authors.affiliation: Centre for Advanced 2D Materials, National University of Singapore , Singapore 117542.|Department of Physics, National University of Singapore , Singapore 117551.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Constans
authors.affiliation: Centre for Advanced 2D Materials, National University of Singapore , Singapore 117542.|Department of Materials Science and Engineering, National University of Singapore , Singapore 117575.
authors.forename: Marcos Vinicius
authors.initials: MV
authors.lastname: Surmani Martins
authors.affiliation: Centre for Advanced 2D Materials, National University of Singapore , Singapore 117542.
authors.forename: Yong Chin
authors.initials: YC
authors.lastname: Seow
authors.affiliation: Centre for Advanced 2D Materials, National University of Singapore , Singapore 117542.|Engineering School, Presbyterian University Mackenzie , São Paulo 01302-907, Brazil.
authors.forename: Juan Alfredo
authors.initials: JA
authors.lastname: Guevara Carrió
authors.affiliation: Centre for Advanced 2D Materials, National University of Singapore , Singapore 117542.|Department of Physics, National University of Singapore , Singapore 117551.|NUS Nanoscience & Nanotechnology Institute, National University of Singapore , Singapore 117581.|Department of Biomedical Engineering, National University of Singapore , Singapore 117583.
authors.forename: Slaven
authors.identifier: 0000-0001-5529-4040
authors.initials: S
authors.lastname: Garaj
keywords: Graphene oxide membranes; ion exchange; ionic permeability; ionic sieving; surface charges