Scalable Graphene-Based Membranes for Ionic Sieving with Ultrahigh Charge Selectivity

Author(s)

Hong, Seunghyun ; Constans, Charlotte ; Martins, Marcos Vinicius Surmani ; Seow, Yong Chin ; Guevara Carrio, Juan Alfredo ; Garaj, Slaven

• Document type: Journal article
• Source: Nano Letters; v. 17, n. 2, p. 728-732, FEB 2017.
• Web of Science Citations: 41

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. (AU)

• FAPESP's process: 13/21190-2 - CVD growth of graphene/h-BN layers, structural characterization and study of layers: water interaction
• Grantee: Juan Alfredo Guevara Carrió
• Support Opportunities: Scholarships abroad - Research