Highly selective sodium alginate mixed-matrix membrane incorporating multi-layered MXene for ethanol dehydration

Abstract

The single/double-layered MXene nanosheets with two-dimensional intergaps and good hydrophilicity have been known as promising porous fillers for preparing high-performance mixed matrix membranes for pervaporation dehydration. However, the single/double-layered MXene nanosheets must be exfoliated from multi-layered MXene (mMXene) through long-time ultrasonication and then be collected through high-speed centrifugation, which limits the facile and large-scale application of single/double-layered MXene nanosheets in membrane fabrication. In this study, mMXene particles with intergaps were directly obtained under mild conditions and then used to fabricate the sodium alginate (SA) mixed matrix membranes. The effects of mMXene content on membrane structure properties and pervaporation dehydration performance were studied. Compared with the pure SA membrane, the SA/mMXene mixed matrix membrane hydrophilicity increases but the degree of swelling decreases with increasing the mMXene content, and the mixed matrix membrane containing 0.12 wt% mMXene in SA shows the 10 times higher separation factor of 9946 and the 24.5% lower permeate flux of 505 g m−2 h−1 for dehydration of ethanol/water (90 wt%) solution. The hydrophilic mMXene fillers attribute to the enhancement in the preferential sorption of water and the constraint in the selective diffusion of ethanol, giving the significant improvement in membrane selectivity.