Opening organic solvent pathways by molybdenum disulfide in mixed matrix membranes for molecular separation

2-dimensional (2D) materials such as molybdenum disulfide (MoS2) present tremendous opportunities in membrane-based, energy-efficient separation. However, the preparation methods of most current 2D membranes are filtration-based and difficult to scale up. This paper reports a fast and scalable approach to fabricate 2D material-based mixed matrix membranes for organic solvent nanofiltration. Via a simple 3-step layer-by-layer coating process, few-layered MoS2 nanoflakes are incorporated into the polyelectrolyte layer, and open the organic solvent pathways which are otherwise closed without MoS2. It is revealed that MoS2 can bridge the strong polyelectrolytes, lower the surface energy and maintain good stability in organic solvents, thereby creating interconnected channels for the selective passage of organic solvents while rejecting solutes. With a thin layer of < 50 nm, the mixed matrix membrane can achieve 92.9% rejection for Victoria blue B (VBB, MW 506.08) with an ethanol flux of 11.4 L m(-2) h(-1) bar(-1).