Efficient CO2 separation by ionic liquid nanoconfined in ultra-thin TCOH@Pebax-1657 MMM

Global climate change has continued to intensify in recent years, and the low efficiency of carbon emission reduction has become an important issue for many countries. Membrane separation technology has gained popularity in CO2 capture due to its ease of operation, environmental friendliness, and smaller area, etc. Twodimensional (2D) sheet materials are one of the most promising materials for membrane separation technology. MXene has been used for gas separation because of its advantages such as high aspect ratio, excellent flexibility, and rich functional group surface. However, the stacking of massive MXene nanosheets lead to gas transport channel obstruction, causing the gas permeance to decrease. Herein, the hydroxylation of MXene was treated to obtain alkaline MXene nanosheets (TCOH) in this work. The stabilised TCOH and Pebax-1657 were used to make a mixed matrix membrane (MMM), while 1-ethyl-3-methylimidazolyl acetate ([EMIm][AcO], IL) was nanoconfined in the 2D channel of ultra-thin TCOH@Pebax-1657 MMM to construct a novel composite membrane for efficient CO2 capture. The TCOH@Pebax-1657/IL membrane prepared in this experiment has high CO2 permeance and the selectivity of CO2/N2, CO2/CH4 at the IL concentration of 35 wt%. In addition, the film has shown excellent thermal stability and durability over long periods of testing. Since TCOH is rarely used in the field of gas separation, the study will provide fresh idea for the preparation of highly efficient CO2 capture membranes.

Automated summary

Global climate change is worsening and the inefficient reduction of carbon emissions is a major concern for many countries. Membrane separation technology, particularly using two-dimensional (2D) sheet materials like MXene, has gained popularity for CO2 capture due to its operational ease, environmental friendliness, and small footprint. However, the stacking of MXene nanosheets restricts gas transport, decreasing gas permeance. In this study, MXene was hydroxylated to obtain alkaline MXene nanosheets (TCOH) for the preparation of a novel composite membrane (TCOH@Pebax-1657/IL) with high CO2 permeance and selectivity.