(646c) Anti-Tradeoff Graphene Oxide Membrane for Organic Solvent Nanofiltration

Two-dimensional (2D) material membranes are highly attractive in precise separations. However, in most of the 2D material membranes, the permeant transport mostly occurs in single-spacing channels with undesired physical and chemical structures. The permeance-rejection trade-off is always a significant challenge, which has received less focus in 2D membranes. In this presentation, by using graphene oxide (GO) as the building block, we design alternating dual-spacing channel membranes, with locally tailored chemical functionalities, that give high permeance, high rejection and high stability in organic solvent nanofiltration. This unique structure is easily constructed by in situ intercalating and cross-linking scattered sub-5 nm silica nanoparticles in the GO interlayers. The hydrophilic nanoparticles locally widen the interlayer channels to enhance the solvent permeance. In the alternating nanoparticle-free areas, the GO layers simultaneously bend and the π–π interactions retain the narrow and hydrophobic channels, promoting high solute rejection. With a 10-fold increase in water permeance and unaffected rejection, the dual-spacing channel membranes exhibit high permeance especially for high polarity organic solvents. The methanol permeance reaches 290 L /m² h bar, with more than 90% rejection of dyes larger than 1.5 nm. This new approach of designing hierarchical channels in 2D materials can be used for a wide spectrum of applications.

Reference:Wang, S.; Mahalingam, D.; Sutisna, B.; Nunes, S^*. 2D-Dual-Spacing Channel Membranes for High Performance Organic Solvent Nanofiltration. J. Mater. Chem. A 2019. DOI: 10.1039/C8TA10872B