The separation of a mixture of toluene and n-heptane with fifty weight percent each was studied with liquid membrane permeation method. The feed to be separated was first emulsified in the surfactant solution. The emulsified droplets coated with surfactant were then contacted with a selected solvent. The more permeable component, toluene, of the mixture easily permeates into the solvent phase. The solvent phase components were separated from solvent by distillation and the surfactant solution were recovered by demulsification. Sodium lauryl sulfate and Tween 60 were used as surfactants, and kerosene as solvent to receive the permeates.
The effects of contact time with solvent, ratio of volume of solvent to that of emulsion, ratio of volume of surfactant solution to that of feed, surfactant concentration and mixing intensity on the system performance were studied by employing a batch mixer-and-settler and a continuous vertical countercurrent permeator.
Especially for the continuous vertical countercurrent permeator the optimum operating conditions were obtained by considering the combined effects of agitation, emulsion viscosity, the differences in specific gravity of emulsion and solvent, and the flow rates of each stream.
Two alternative separation processes, i.e., the present liquid membrane method and the traditional solvent extraction with diethylene glycol, were compared on the basis of capital and operating cost.
