Selective Partitioning of Organic Liquid Mixtures by Pristine Graphene Layers

ABSTRACT

Carbon nanomaterials offer a highly effective and energy‐efficient route for achieving precise molecular separations compared to traditional methods such as distillation. Here, we use pristine graphene sheets to isolate a range of organic liquid mixtures via molecular dynamics simulations. By arranging two graphene sheets in parallel and systematically varying their interlayer distances, we separate six benzene‐based binary mixtures containing cyclohexane, p‐xylene, THF, butanol, isopropanol, and ethanol. We achieve 100% separation in all six liquid mixtures by keeping a short interlayer distance of 0.6 nm. A single layer of benzene molecules, oriented parallel to both graphene layers, gets selectively partitioned within the available volume. Similarly, the formation of a bilayer of benzene is observed by increasing the interlayer distance to 1 nm, except for p‐xylene, which also gets integrated into the bilayer along with benzene. Further increasing the distance to 3 nm results in almost equal occupancy of both liquids within the layers. The parallel orientation of benzene toward graphene vanishes from 2.9° to 48° with rise in interlayer distance from 0.6 to 3 nm, respectively. The number densities of benzene and cosolvents within the layers depict various patterns, mainly illustrating a higher affinity of both the liquids toward graphene walls.