Industrial Applications of Ionic Liquids in Acetonitrile-Water Azeotrope Separation: Molecular Dynamics and DFT Insights into Azeotrope Breaking Methods

초록

Separating acetonitrile-water azeotropic systems is challenging due to unclear molecular-level interaction mechanisms of ionic liquids (ILs). This study investigated ILs ([Emim]Br, [Bmim]Br, [Emim][BF4], and [Bmim][BF4]) as entrainers using experimental and theoretical approaches to elucidate the azeotropic point-breaking mechanism. Molecular dynamics (MD) simulations were employed to analyze binary and ternary solutions, while density functional theory (DFT) at B3LYP/6-311 + G(d) was used to refine the complexation energies and Boltzmann-averaged multiple isomers. Vapor-liquid equilibrium (VLE) data (T, x, and y) for the pseudobinary systems of acetonitrile, water, and ILs at 101.33 kPa were measured and correlated using the nonrandom two-liquid (NRTL) model. The results show that ILs exhibit a stronger salting-out effect than solvation, enhancing the relative volatility of acetonitrile and eliminating the azeotropic point. The salting-out efficacy followed the order [Emim]Br > [Bmim]Br > [Emim][BF4] > [Bmim][BF4], with [Emim](+) and Br- being the most effective. These findings highlight the ILs' potential for efficient, sustainable industrial azeotrope separation.

키워드