High-performance porous graphene oxide hollow fiber membranes with tailored pore sizes for water purification

Though graphene oxide (GO) membranes hold a good promise for water purification, their performance is restricted by permeation through long and tortuous diffusional pathways, leading to lower water permeance. In this study, we proposed a mild chemical etching approach to create nano-scale pores on the basal plane of GO nanosheets to make hollow fiber (HF) porous GO (PGO) membranes with improved water permeance and good dye rejection performance. Various characterization techniques were performed to monitor the pore generation and structural and compositional changes of synthesized PGO nanosheets. Results revealed that by controlling the etching time, PGO nanosheets with tunable pore size and surface chemistry as well as good solution processability were synthesized. The fabricated PGO HF membranes showed a well-stacked laminar morphology with uniform structures. The membrane made of PGO nanosheets etched for 5h (named PGO_5h) exhibited a 23-fold enhancement in pure water permeance from 0.129 LMHBar−1 for pristine GO membrane to 2.98 LMHBar−1. Rejection tests with dyes in the molecular weights range between 200 and 900 g mol−1 were performed to prob the sieving capacity of the membranes on dye-containing wastewaters. The PGO_5h membrane showed molecular weight cut-off (MWCO) about 500 g mol−1, demonstrating the great potential of PGO HF membranes for nanofiltration applications.