Graphene oxide membranes with fixed interlayer distance via dual crosslinkers for efficient liquid molecular separations

Abstract

The interlayer distance of stacked graphene oxide (GO) membranes is the decisive factor of achieving high permeability and selectivity. Fixating the size of 2D channel in GO membrane proves a critical challenge for liquid separation. Herein, GO membrane was firstly crosslinked by polyvinylamine (PVAm) to acquire mechanically stable membrane, and PVAm then induced the biomimetic mineralization to in situ generate silica as the second crosslinker to further fixate the size of 2D channels. The interlayer distance of GO-PVAm-Silica membrane fixed around 0.62 nm in water, showing the improved swelling resistance compared to the GO-PVAm membrane. The resultant GO-PVAm-Silica membrane featured high water permeability as well as distinct sieving properties for bio-alcohol molecules and hydrated ions. To be specific, the membrane exhibited a superior pervaporative dehydration performance with separation factor of 1188 ± 39 and flux of 12.9 ± 0.3 kg/(m2h) under 80 °C for 90 wt% butanol/water mixture. And the membrane showed a high NaCl rejection rate of higher than 99.99% and total permeation flux of 80.2 ± 0.8 kg/(m2h) when treating 3.5 wt% NaCl solution under 70 °C. Moreover, the GO-PVAm-Silica membrane kept excellent operation stability in 168 h test.