Constructing large loadings of dual pathways with Ti3C2Tx-CDs in thin film nanocomposite membrane for enhanced organic permeation

Abstract

Dual pathways hold great superiority in facilitating molecular permeation for various separation applications. However, the existing dual-pathway nanostructure fails in realizing large loadings of dual pathways and hence limited molecular permeation. Here, cyclodextrins (CDs) with hydrophilic exterior surface but strong hydrophobic interior cavity are utilized and anchored on Ti3C2Tx nanosheets, thus constructing large loadings of dual pathways. The resultant building blocks (Ti3C2Tx-CDs) are integrated into hydrophilic polyethyleneimine (PEI) matrixes to prepare thin film nanocomposite (TFN) membranes. Ti3C2Tx-CDs offer the advantage of forming large loadings of dual pathways by anchoring quantities of CDs on Ti3C2Tx nanosheets, thanks to the abundant –OH groups of Ti3C2Tx nanosheets. The hydrophobic internal cavities of CDs work as transfer highways for nonpolar solvents, while hydrophilic PEI matrixes afford for polar solvents, imparting to the membranes enhanced organic permeation. For isopropanol, TFN-Ti3C2Tx-β-CDs attains the permeation of 3.8 L m−2 h−1 bar−1. For n-heptane, more striking augment in permeation is observed for TFN-Ti3C2Tx-β-CDs, reaching 2.7 L m−2 h−1 bar−1, 9 times of control membrane (TFN-Ti3C2Tx) value. Moreover, these TFN membranes display superior structural stability, guaranteeing great potential for applications in sophisticated organic solvent systems.