Guozhen Liu,Jie Shen,Yufan Ji,Quan Liu,Gongping Liu,Jian Yang,Wanqin Jin
Two-dimensional (2D) material membranes have shown great potential for molecular separation. However, it remains challenging to controllably tune 2D material membrane structures with ordered nanochannels without non-selective defects. Herein, for the first time, 2D Ti2CTx MXene membranes were designed and fabricated for efficient solvent dehydration via a new strategy. Specifically, positively charged hyperbranched polyethylenimine was intercalated between negatively charged MXene nanosheets to assemble regular stacking structures via electrostatic interactions, followed by interfacial polymerization with trimesoyl chloride to seal possible non-selective defects. This strategy realized integrated Ti2CTx membranes as thin as ∼100 nm with highly ordered 2D nanochannels, thereby exhibiting outstanding separation performance: the water content was enriched to >99 wt% in permeate from 10 wt% water/isopropanol mixtures. Compared with commonly studied Ti3C2Tx MXene membranes prepared by the same approach, the Ti2CTx membranes showed higher selectivity with similarly high flux. The membrane fabrication approach developed herein offers a powerful platform for the rational design of 2D material thin films for precise molecular separation and other applications.
Guozhen Liu,Song Liu,Kang Ma,Haoyu Wang,Xiaoyue Wang,Gongping Liu,Wanqin Jin
Recently, owing to their excellent structural and transport properties, two-dimensional membranes have attracted tremendous interest for their potential application in molecular separation. In this work, a new type of functionalized Ti2CTx MXene membrane was proposed by introducing different kinds of polyelectrolytes to regulate the membrane physicochemical structure for pervaporation dehydration of isopropanol dehydration. The morphology, physical, and chemical properties of powders and MXene-based membranes were studied by SEM, AFM, FTIR, XPS, and contact angle test. Meanwhile, the effect of polyelectrolyte functionalization on the MXene membrane performance for isopropanol dehydration was also studied. The results showed that the poly(diallyldimethylammonium chloride) (PDDA) functionalized MXene membrane possesses the highest separation performance owing to the optimized electrostatic effect and hydrophilicity. Besides, other influencing factors including PDDA concentration, MXene loading, and operating conditions on the MXene membrane performance were also systematically investigated. The developed PDDA functionalized MXene membrane showed excellent separation performance for dehydration of 90 wt % isopropanol/water at 50 °C with a total flux of 1237 g/m2·h and separation factor of 1932, showing great potential in application of solvent dehydration.
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