Cyclodextrin cross-linked 2D Ti3C2Tx MXene membranes for organic solvent nanofiltration

Abstract

Construction of well-confined sub-nanochannels for molecular-sieving in organic solvent environment remains a challenge for organic solvent nanofiltration (OSN) membranes in precise fluid separation. Herein, cyclodextrin (CD) cross-linked 2D Ti₃C₂T_x MXene membranes with laminar nanostructure containing unique sub-nanoscale mass transfer channels for unprecedented OSN performance is reported. Density-functional theory (DFT) calculation and experimental results confirm that CD monomers (α-, β-, γ-) with 3D intrinsic cavity structures are anchored with Ti₃C₂T_x MXene nanosheets forming a stable polyester cross-linking network via an interfacial molecular engineering using trimesoyl chloride (TMC). The prepared membranes exhibit ultrahigh OSN performance with excellent stability in organic solvents. The optimal membrane can effectively reject dyes such as methylene blue (99.8%), rhodamine B (98.0%), and Congo Red (100%), while having high ethanol permeability ranging from 22.58 to 85.31 L/(m² h bar). Remarkably, the membrane structure remained intact after 4 weeks immersion in ethanol and acetone. This work provides a facile and reliable strategy to construct a high-performance 2D material-based OSN membrane with well-confined mass transfer channels.