Liquid-liquid extraction of polyaromatic compounds with ionic liquid. A theoretical and experimental approach

Abstract

Recent legislation worldwide aims to reduce the levels of polyaromatics compounds in lubricant bases due to their harmful effect on health. Ionic liquids have obtained broad interest as green recyclable extractants. Here, we presented new experimental data of liquid-liquid extraction implementing ionic liquids for the removal of aromatics compounds of synthetic crude oil in a 1:1 mass/mass ratio for temperatures ranging from 303.15 to 293.15 K. Selectivity and distribution constant data are obtained to know the extractive potential of each ionic liquid. To support the experimental results, several computational calculations have been performed. First, two predictive thermodynamic models COSMO-SAC and UNIFAC, have been applied, and the reliability of both models has been compared with experimental results. The results show that using UNIFAC is more accurate than using COSMO to predict extraction behavior. Second, the extractive process has been studied using molecular dynamics. This tool allows us to understand better how the extraction process occurs and the molecules’ situation when they reach equilibrium. It is shown that the cation of the ionic liquid is the primary driver of liquid–liquid extraction. In addition, molecular dynamics will enable a qualitative comparison between the performance of ionic liquids and the experimental results. It is a helpful tool to save time and material resources before laboratory experimentation.