Separation of coal tar absorption oil by an ionic liquid supported liquid membrane

Abstract

The separation of coal tar absorption oil by an ionic liquid supported liquid membrane was studied to recover nitrogen heterocyclic compounds.Batch permeation runs with the supported liquid membrane were conducted using an absorption oil-heptane solution as the feed, an aqueous solution of the ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, as the membrane liquid, and toluene as the solvent. Under all conditions, the nitrogen heterocyclic compounds selectively permeated through the membrane compared to other compounds. The permeation rates, especially for indole, significantly increased with the addition of the ionic liquid. The overall permeation coefficients increased with the addition of the ionic liquid and the separation selectivity of indole to 2-methylnaphthalene increased.