Tailoring the interlayer channel structure of graphene oxide membrane with conjugated cationic dyes for butanol dehydration

For the design of high-performance GO membrane, the structure of intercalation material is a key consideration due to its decisive impacts on nanosheet assembly and mass transfer channel structure. Herein, conjugated cationic dyes were incorporated into GO interlayer channels. The large π-conjugated structure and delocalized positive charge can form π-π and electrostatic interactions with the non-oxidized region and negatively-charged group on GO nanosheet, respectively. Through interlayer cross-linking, the nanosheet orientation and interlayer bonding can be improved, conferring the membrane with higher anti-swelling capacity, more ordered channel structure, and controllably tailored interlayer d-spacing. The electron cloud density and planar structure of cationic dye molecules are evidenced to be critical in influencing membrane structure and separation performance. After incorporating conjugated cationic dyes, the separation factor for water/butanol separation can reach 5.3 times of that of pristine GO membrane, while the permeate flux also increases by 20%. This work provides a category of promising intercalation materials for GO membranes with good potential application in butanol dehydration.