Efficient separation of phenols from coal tar with aqueous solution of amines by liquid-liquid extraction

Abstract In this paper, a method of extracting phenols from coal tar by organic amine aqueous solution was proposed. The effects of various amines on the extraction properties of phenols in coal tar were researched from the views of molecular structure. The parameters such as molar ratio, concentration, extraction time and temperature for the extraction of coal tar by the monoethanolamine and ethylenediamine aqueous solution were examined. The results show that the organic amine with more amino groups, hydroxyl structure and strong electronegativity exhibited better extraction performance. Under the optimal conditions, the extraction yields of phenols in coal tar by the monoethanolamine or ethylenediamine aqueous solution are above 80%, and the recovery yields of amines reach 99%. Furthermore, the probable geometries of complexes formed by the combination of phenols and organic amines were calculated by density function theory. In addition, several thermodynamic models were evaluated through comparing the relative deviation of simulation results by ASPEN PLUS to the experimental ones, which provide feasibility thermodynamic models for the simulation of extraction process. The present work affords a mild, efficient and green approach for the extraction of phenols from coal tar by an aqueous solution of amines in industry application.