Controlling interlayer spacing and organic solvent permeation in laminar graphene oxide membranes modified with crosslinker

Two-dimensional (2D) laminar membranes are attracting much attention in organic solvent nanofiltration owing to the promising permeation and selective performance derived from their 2D ultrathin separation layer. However, owing to easy swelling (enlargement of interlayer spacing), controlling the interlayer spacing in organic solvents and stable solvent permeation are major issues for their application to organic solvent systems. In this study, laminar GO membranes were fabricated on a porous polyketone (PK) support membrane using triethanolamine (TEOA) as crosslinker (GO-TEOA/PK). The interlayer spacing (d) between GO sheets was characterized by X-ray diffraction. The TEOA crosslinker effectively suppressed swelling of the GO laminar structure. For GO-TEOA/PK, the variation in d corresponded well with the affinity between TEOA and each solvent, Ra(TEOA-solvent), as estimated using the Hansen solubility parameters. Furthermore, common linear correlation between the permeance of alcohols and the parameter combining affinity, viscosity, and equivalent molar diameter was clearly observed. Therefore, the affinity between crosslinker and solvent was an important factor in controlling interlayer spacing and solvent permeation in the laminar GO membranes containing crosslinker.

Automated summary

Two-dimensional (2D) laminar membranes are being studied for organic solvent nanofiltration, but controlling interlayer spacing and stable solvent permeation remain challenges. In this study, GO membranes with TEOA crosslinker were found to effectively suppress swelling and the affinity between TEOA and solvents correlated with interlayer spacing, indicating the importance of crosslinker-solvent affinity in controlling membrane performance.