Collaborative intercalation and reduction of graphene oxide for highly stable and efficient nanofiltration membranes

Abstract

Two-dimensional (2D) materials, known for their atomically thin profiles and micrometer transverse dimensions, have garnered considerable attentions in membrane technology. Despite their potential, 2D membranes comprising stacked nanosheets often suffer from low permeability and poor stability. Addressing these challenges, we applied collaborative intercalation and reduction strategies to enhance permeability and stability of graphene oxide (GO)-based membranes. We intercalated 2-hydroxypropyl-β-cyclodextrin (2β-CD) into the GO nanosheet dispersion under heat treatment and employed vacuum assisted self-assembly to fabricate the 2β-CD intercalated reduced GO (CD-rGO) membrane. During this process, GO nanosheets underwent reduction, facilitating the formation of hydrogen bonds between 2β-CD and GO. The resulting CD-rGO membrane exhibited markedly improved water permeance at 96.9 L m−2 h−1 bar−1 and an impressive rejection rate at 99.5 % towards Congo red, alongside enhanced stability under a 20 min ultrasonic test at 180 W, and pressure and long-term stability under the cross-flow filtrate tests. The introduction of 2β-CD during heat treatment not only increased the interlayer distance but also utilized the intrinsic pores of 2β-CD and enhanced surface hydrophilicity, contributing to superior separation performance These collaborative strategies offer a facile and promising approach towards high-performance 2D laminated GO-based membranes.