Efficient separation of (C₁–C₂) alcohol solutions by graphyne membranes: A molecular simulation study

With well-endowed nanopores, graphyne (GY) membranes have attracted considerable interest in alcohol purifications. However, the challenge lies in the rational design of GYs for efficient separation of (C₁–C₂) alcohol solutions. Herein, GYs are firstly developed for methanol recovery and ethanol dehydration by molecular simulations. Two design strategies including surface charge modification and functional group decoration are proposed in this study. For methanol-water separation, methanol is pre-selected due to the dominated mechanism of preferential adsorption and its flux increases with positive charges within a certain range. An excellent separation performance with 99.1 kg⋅m^-2⋅h^-1 methanol flux and 15.2 separation factor is achieved by this GY-S membrane with +0.005 e/atom charged surface. This surface charge modification is also effective for methanol-ethanol separation, where the highest performance is harvested by the positively charged GY-M membrane. For water-ethanol separation, water is pre-selected owing to the size sieving effect. To reduce the blocking effect and permeation barrier, the GY-M is functionalized with polar groups so that water flux is promoted regardless of aperture sizes. The hydroxylated GY-M-OH fosters an exceptionally high dehydration performance with 225.8 kg⋅m^-2⋅h^-1 water flux and 100 wt% water content in permeate. This theoretical study suggests that the GYs membranes might be promising for organic solvent recovery and dehydration.