1. Scalable Graphene-Based Membranes for Ionic Sieving with Ultrahigh Charge Selectivity
- Author
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Juan Alfredo Guevara Carrió, Slaven Garaj, Charlotte Constans, Marcos Vinicius Surmani Martins, Seunghyun Hong, and Y. C. Seow
- Subjects
Chemistry ,Mechanical Engineering ,Analytical chemistry ,Ionic bonding ,Bioengineering ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Electrostatics ,01 natural sciences ,0104 chemical sciences ,Ion ,Ionic potential ,Membrane ,Solvation shell ,Chemical engineering ,General Materials Science ,Nanofiltration ,Surface charge ,0210 nano-technology - 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.
- Published
- 2017