Exclusive and fast water channels in zwitterionic graphene oxide membrane for efficient water–ethanol separation

Abstract

Graphene oxide (GO) membranes have shown great prospects as the next‐generation membranes to tackle many challenging separation issues. However, the employment of GO membranes remains difficult for the precise separation of molecules with strong coupling effect and small size discrepancy such as water–ethanol. Herein, a new strategy of constructing exclusive and fast water channels in GO membrane was proposed to achieve high‐performance water–ethanol separation via the synergy between zwitterion‐functionalized GO and hydrophilic polyelectrolyte. The as‐formed ordered and stable channels possess high‐density ionic hydrophilic groups, which benefit from inhibiting the strong coupling between water and ethanol, facilitating the fast permeation of water molecules while suppressing ethanol molecules. As a result, the ultrathin GO‐based membrane acquires exceptionally high separation performance with a flux of 3.23 kg/m2 h and water–ethanol separation factor of 2,248 when separating water–ethanol (10 wt%/90 wt%) mixture at 343 K. This work paves a feasible way to construct 2D channels for the high‐efficiency separation of strong‐coupling mixtures.

Charged Boron Nitride Nanosheet Membranes for Improved Organic Solvent Nanofiltration

“…The accumulated repel effect of the dye-adsorbed membrane further improves the molecule separation, which is in accordance with the real separation performance in solutions. The improved ζ-potentials of charged PBN and SBN experimentally contributed to dye molecule separation due to the classical electrostatic interaction effects. − The PBN and SBN nanosheets showed ζ-potential values of 55 and −63 mV, respectively, which were higher than that of the pristine BN nanosheets (−26 mV). Hence, the interaction of the polyelectrolyte and dye molecules not only modifies the BN nanosheets but also supports an abundant microenvironment for sieving dye molecules.…”

Insights into High Li+/Mg2+ Separation Performance Using a PEI-Grafted Graphene Oxide Membrane

“…The C 1s XPS spectra of the GO membrane can be fitted to three peaks, where the binding energy located at 284. 44 In addition, we further analyzed the N 1s peak for the GO−PEI membrane (Figure S9 in the Supporting Information). The N 1s spectra were fitted charged amine groups at 401.2 eV and uncharged amine groups at 399.5 eV.…”

Recent Advancements in the Recovery and Reuse of Organic Solvents Using Novel Nanomaterial-Based Membranes for Renewable Energy Applications

“…The commercial use of GO membranes continues to be challenging for the molecule separation process with strong coupling effect and less size inconsistency such as water–ethanol. In a very recent article, a new exclusive technique of constructing quick water channels in GO membrane was demonstrated for enhanced water–ethanol separation combining the synergistic effects between hydrophilic polyelectrolyte (polyethylenimine) and zwitterion-functionalized GO, as shown in Figure 16 [ 76 ]. The built in ordered and steady channels contained ionic hydrophilic groups with a high density, which plays a role in negating the strong coupling force between ethanol and water, allowing the water molecules to quickly permeate and restricting the transport of ethanol molecules.…”