Synergistically tailoring the hierarchical channel structure of graphene oxide membrane through co-assembly strategy for high-performance butanol dehydration

A significant boost in permeate flux along with the desirable separation factor remains a challenging issue for graphene oxide (GO) membranes in pervaporation applications. Herein, a facile approach of co-assembling pristine and etched GO nanosheets was proposed to tailor the hierarchical channel structure (involving the slits, defects and interlayer galleries) of GO membrane and achieve remarkable improvements in both the permeate flux and water/butanol separation factor. Pristine GO nanosheets guarantee a defect-free membrane structure, while etched GO (eGO) provides abundant defects/slits for molecular transport, thus reducing molecular diffusion resistance and doubling permeate flux. The introduction of eGO confers a more ordered nanosheet assembly and narrower interlayer spacing, thus strengthening the size-exclusion effect of the interlayer channels towards butanol molecules and realizing a 3-times enhancement in the separation factor. The subsequent intercalation of Congo red (CR) molecules ulteriorly optimizes the interlayer channels and results in the superior water/butanol separation factor of 5705 with the permeate flux of 4.81 kg/(m2h). This work provides a facile and feasible method for constructing high-performance GO-based membranes with great potential for practical butanol dehydration process.