Our research group has investigated the prediction of liquid-liquid equilibrium (LLE) of a ternary system consisting of benzene + hexane/heptane ionic liquids using the UNIFAC-Lei model.
All extraction process for separating benzene from its mixtures contacting hexane/heptane were simulated by Aspen Plus V8.4.
The liquid extractor was chosen as a unit operation and kept constant at 298.15K, 101.32kPa. The stock solution was simulated at 80wt% of hexane/heptane and 100kg/h mass flow. The mass flow of solvent was varied from 0.5 to 0.4 to obtain the solvent to feed ratio (IL/F).
Then, the mass flow of each component was calculated at different equilibrium stages (NS) from 2 to 6.
Finally, the processes were optimized by sensitivity analysis as a function of IL/F and NS.
The results show that the raffinate stream scarcely contains and ionic liquid.
The selectivity estimated for ternary systems containing hexane, benzene and ionic liquid decease in the following order when used homogeneous ionic liquids with [NTf2] anions.
[EMIM][NTf2] > [BMIM][NTf2] > [OMIM][NTf2] > [DMIM][NTf2]
This trend is consistent with the experimental results.
The selectivity of ionic liquid [EMIM][NTf2] is higher than that of other ionic liquids [BMPY][NTf2], [OMIM][Cl], [HMIM][BF4].
The ternary systems of heptane, benzene and ionic liquids were also observed as remarked above.
Separation of hexane/heptane and benzene using ionic liquids, especially [EMIM][NTf2], is possible from the results of the LLE phase equilibrium estimation and the extraction process simulation.
These data demonstrate the feasibility of theoretical operating conditions for operating a continuous extraction process at the room temperature.
It is also possible to implement on an industrial scale.
Thus, the UNIFAC-Lei model can be a very useful estimation tool for screening ionic liquids and the design of the extraction process based on ionic liquid.
The results were published in "International Journal of Chemical Technology" under the title of "Investigation on the feasibility of separation process for extracting benzene from hexane/heptane by ionic liquids"(http://doi.org/10.56042/ijct.v32il.5199).
