Efficient extraction and theoretical insights for separating o‐, m‐, and p‐cresol from model coal tar by an ionic liquid [Emim][DCA

Abstract

AbstractCresols are valuable phenolic chemicals which are mainly separated from coal tar. The separation of cresols using sustainable technology is of importance for comprehensive utilization of coal tar. In this work, for extracting o‐, m‐, and p‐cresol from the model coal tar, an ionic liquid 1‐ethyl‐3‐methylimidazolium dicyanamide ([Emim][DCA]) was prepared. The influence of ionic liquid dosage, extraction time, and temperature on separating o‐, m‐, and p‐cresol was explored. The extraction efficiency was determined from the experimental results to assess the extraction ability of [Emim][DCA]. With the optimal conditions, o‐, m‐, and p‐cresol were extracted efficiently from the model coal tar and the extraction efficiencies of o‐cresol, m‐cresol, and p‐cresol were up to 99.50%, 99.65%, 98.38%, respectively. In the meantime, the extraction mechanism was determined by calculation of σ‐profile, interaction energy, and electron density. The results showed that [Emim][DCA] and cresols formed the complexes by hydrogen bond. The formation of hydrogen bond was verified by the FTIR spectra, which is helpful for designing the related ionic liquids for recovering the phenolic compounds from coal tar. In addition, the recyclability of the [Emim][DCA] was explored.