Separation of Phenols from Oil Using Imidazolium-Based Ionic Liquids

Abstract

Phenolic compounds, which are important substances in industry, are mainly derived from coal liquefaction oil, coal tar, and petroleum, and also from biomass via pyrolysis. However, the traditional process of separation of phenols from oil using water, NaOH, and H 2 SO 4 causes serious environmental problems. In this work, imidazolium-based ionic liquids (ILs) were used to extract phenol from a model oil of hexane and phenol in order to reduce environmental risk. It was found that these ILs could successfully separate phenols from hexane, and a small amount of [Bmim]Cl, equimolar to that of phenol in hexane, was enough to extract phenol with a high extraction efficiency of 99%. Anions of imidazolium-based ILs have a significant influence on the phenol extraction efficiency, which follows the order: Cl − > Br − > BF 4 − > PF 6 − . But the cation of these ILs shows a relatively small influence on the extraction. Particularly, [Bmim]Cl shows best performance in terms of phenol extraction efficiency. Furthermore, it is not sensitive to temperature changes and can be performed at ambient temperature. The extracted phenol in ILs could be recovered by evaporation, and the regenerated ILs could be reused for four cycles with no obvious loss in the phenol extraction efficiency. [Bmim]Cl was also used to extract phenols from real coal liquefaction oil, and the extraction efficiency of phenols could reach 90%.

An ionic liquid extraction process for the separation of indole from wash oil

“…ILs gradually became an alternative to conventional organic solvent. They performed well in the separation and extraction of many compounds, such as metal 9, 10 , organic acids 11 , amino acids 12,13 , biofuels 14 , benzene derivatives 15 , and phenolic compounds [16][17][18][19] . The conventional extraction solvent of indole was changed from one polar solvent (methylacetamide) to two solvents (a polar solvent and non-polar solvent) 20 .…”

Pretreatment of coal by ionic liquids towards coal electrolysis liquefaction

“…As shown in . It is possibly due to the interactions between imidazolium-based ILs with coal particles, such as the p-p conjugation between the imidazolium cation and aromatic rings [29], and larger charge density and electronegativity of Cl À ions compared with other anions [30]. Extract yield of the coal sample in [Bmim]Cl reaches to 18.51% at 90°C.…”

The new liquid–liquid extraction method for separation of phenolic compounds from coal tar

“…Fan et al [23] used an imidazolium ionic liquid as the extraction agent to separate phenols from aqueous solutions and optimized the experimental parameters, most phenols were extracted quantitatively to the ionic liquid phase. Hou et al [24] used an imidazolium-based ionic liquid to extract phenols from model oil, with a removal efficiency that exceeded 95%. Egorv et al [25] used a novel ionic liquid incorporating quaternary ammonium cation to extract phenols and aromatic amines efficiently, and its solute distribution ratio can reach as high as n  10 4 .…”