Realizing small-flake graphene oxide membranes for ultrafast size-dependent organic solvent nanofiltration

Abstract

Membranes for organic solvent nanofiltration (OSN) or solvent-resistant nanofiltration (SRNF) offer unprecedented opportunities for highly efficient and cost-competitive solvent recovery in the pharmaceutical industry. Here, we describe small-flake graphene oxide (SFGO) membranes for high-performance OSN applications. Our strategy exploits lateral dimension control to engineer shorter and less tortuous transport pathways for solvent molecules. By using La3+ as a cross-linker and spacer for intercalation, the SFGO membrane selective layer was stabilized, and size-dependent ultrafast selective molecular transport was achieved. The methanol permeance was up to 2.9-fold higher than its large-flake GO (LFGO) counterpart, with high selectivity toward three organic dyes. More importantly, the SFGO-La3+ membrane demonstrated robust stability for at least 24 hours under hydrodynamic stresses that are representative of realistic OSN operating conditions. These desirable attributes stem from the La3+ cross-linking, which forms uniquely strong coordination bonds with oxygen-containing functional groups of SFGO. Other cations were found to be ineffective.

The stability of a graphene oxide (GO) nanofiltration (NF) membrane in an aqueous environment: progress and challenges

“…5A and B). 37,[69][70][71][72][73] This is because the GO nanosheets can be cross-linked by a multivalent cationic metal via formation of a coordination bond. These above-mentioned strategies can effectively improve the water permeation flux, but the swelling is still obvious, which may result in a decrease in the rejection rate.…”

2D Material Based Advanced Membranes for Separations in Organic Solvents

“…Although their separation mechanisms are still not fully understood, the demonstrated ultrafast organic solvent permeance and excellent stability suggest that GO-based membranes may be a promising candidate for various separation applications in organic solvents. Some membrane modification methods, such as tailoring surface chemistry of GO-based nanosheets [13,15,80] and controlling their interlayer spacings, [13,16,53,81] offer opportunities to improve the performance of GO-based membrane further.…”

Nanocomposite Membranes for Liquid and Gas Separations from the Perspective of Nanostructure Dimensions

“…As the separation mechanism of 2D nanosheets is primarily governed by the distance or tortuosity of the transport pathways, the control of lateral dimension of 2D nanofillers is useful to maximize the transport capacity [ 132 ]. By manipulating the exfoliation conditions, small- and large-flake GO nanosheets with lateral dimension of 0.03 μm 2 and 0.51 μm 2 can be obtained [ 133 ]. Using methanol as a model fluid, the nanocomposite membrane assembled with small-flake GO exhibited up to 2.7-fold higher permeance than the large-flake counterpart.…”

“… ( a ) Schematic illustration of solvent molecule transport pathway in small-flake graphene oxide (GO) and large-flake GO with different lateral [ 133 ], cross-sectional images of polyethersulfone (PES) support layers templated with ( b ) ZnO nanoparticles and ( c ) ZnO nanorods [ 134 ]. …”