Graphene oxide (GO) has been extensively investigated for membranes for dye removal from wastewater owing to its strong molecular size-sieving ability. GO membranes are often reduced or cross-linked to improve the stability in water, which, however, decreases water permeance. Herein we demonstrate an effective approach to enhance both durability and water permeance and retain dye rejection by synergistically integrating chemical etching and intercalation with polydopamine (PDA) to create hierarchical nanochannels. Specifically, GO nanosheets were etched using H<sub>2</sub>O<sub>2</sub> to obtain HGO, which were then co-deposited with dopamine onto porous supports. The nanopores created on the HGO shorten the diffusion path, increasing the water permeance, while the PDA intercalation changes the channel sizes and stabilizes the GO nanosheets. An optimized membrane exhibits water permeance of 120 LMH/bar (one order magnitude higher than state-of-the-art commercial polyamide membranes) and a Congo Red rejection of 98.5%, better than GO membranes reported in the literature. Moreover, the membrane exhibits stable performance in a 3-day continuous crossflow filtration test. The versatile approach reported here may be applied to other two-dimensional materials to create hierarchical nanochannels for desired separations.

Engineering hierarchical nanochannels in graphene oxide membranes by etching and polydopamine intercalation for highly efficient dye recovery

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.