Super-crosslinked graphene oxide membranes with enhanced stability and selectivity for efficient alcohol/water separation via pervaporation

Pervaporation (PV) is a promising membrane technology for biofuel production, separating alcohol-water mixtures. Lamellar graphene oxide (GO) membranes have shown great potential in alcohol dehydration, but achieving high dehydration efficiency and robust stability of lamellar GO membrane still remains challenge. Herein, a lamellar GO membrane was intercalated and covalently crosslinked using polyethyleneimine (PEI) and sulfosuccinic acid (SSA) to construct a robust three-dimensional super-crosslinking structure. The PEI crosslinking with GO formed amide bonds, which was intensified by increasing PEI content and thermal treatment, leading to tightened stacking of GO nanosheets. The carboxyl groups of SSA reacted with excess amino groups of PEI enabling remarkably increased crosslinking density and size-sieving effect for improved separation. The optimized crosslinking and separation were realized based on balanced interactions between GO and the crosslinkers as well as appropriate thermal treatment. The super-crosslinked membrane exhibited excellent PV performance with a high flux of 4.033 kg m⁻² h⁻¹ and an exceptionally high water-to-butanol separation factor of 9774 in dehydrating 90 wt% n-butanol at 60 °C. The membrane exhibited exceptional structural stability verified by a pervaporation-ultrasound multiple cycle test. This work provides a new approach to tuning structure and property of GO membrane, advancing their application for efficient liquid separation.