Constructing novel GO microcomposite membranes with β-CD based microporous nanosheets for efficient dye/salt separation

Abstract

Graphene oxide (GO) membrane is considered as one of the preferred choice for textile wastewater treatment thanks to its unique 2D interlayer channel features. However, GO laminar stacking is inclined to water-induced structure instability, and the narrow interlayer spacing limit mass transport efficiency, hampering its effectiveness in water treatment applications. Herein, a layer-by-layer stacked microcomposite membrane based on GO and highly microporous β-cyclodextrin based nanosheets (β-CDNS) served as intercalator was developed. The distinctive layered structure was further stabilized by covalent cross-linking with glutaraldehyde (GA). The microporous β-CDNS offered additional nanochannels that facilitated the rapid penetration of water molecules, while the abundant -OH groups provided sites for chemical cross-linking, enhancing membrane stability. The optimal GO/β-CDNS1 membrane exhibited a superior water permeance of up to 83.5 LMH/bar, with >99 % rejection for dyes such as Congo red (CR), methyl blue (MB), and chrome black T (CBT), 95.5 % for acid fuchsin (AF). Meanwhile, the GO/β-CDNS1 membrane demonstrated ultra-low (<5 %) retention for inorganic salts (MgSO4, MgCl2 and NaCl), with a separation factor as high as 194 for MB/NaCl mixtures. Therefore, employing functional interlayer nano-additives to well regulate the GO interlayer structure offers a promising guideline for developing high-performance GO-based membranes.