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BACKGROUND: Phenol is an important chemical and has many applications in industry. It is mainly produced from coal tar. At present, the commonly used method in industry is caustic washing, which produces a lot of wastewater containing phenolic components, resulting in environmental contamination. Herein, a dual-functionalized ionic liquid, 1-hydroxyethyl-3-methylimidazolium propionate, was synthesized as a candidate for recovering phenol from a coal tar oil mixture. RESULTS:The performance of the ionic liquid was investigated by extraction experiments with various factors, including phase ratio, contact temperature and contact time. The optimal separation conditions for removing phenol using the ionic liquid were as follows: m DFIL :m oil = 1:5; contact temperature, 25°C; contact time, 30 min. The corresponding removal efficiency was 95.9%. The intermolecular interaction for separating phenol with the ionic liquid was verified to be hydrogen bond attraction using quantum chemical calculations and Fourier transform infrared spectrometry. CONCLUSIONS:The experimental and calculated results showed that 1-hydroxyethyl-3-methylimidazolium propionate was a suitable extractant for removal of phenol from the oil mixture. This provides a reference for the dephenolization process of coal tar in industry.

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Three pyridinium-based ionic liquids (ILs) were adopted to extract isopropanol (IPA) from its aqueous mixture for investigating the potential of these ILs in the separation of a (water + IPA) azeotropic mixture. The liquid–liquid equilibrium values for the mixtures (water + IPA + ILs) was determined at 298.15 K. The selectivity and distribution coefficient were computed, which indicates that the IL n-hexylpyridinium bis­(trifluoromethyl sulfonyl)­imide displays a better extraction effect to separate the mixture of IPA and water. Besides, the NRTL model was applied to regress the determined tie-line values, and the coherence of the optimized binary parameters was examined using the Gibbs energy surfaces analysis.