Supercritical carbon dioxide fractionation of peppermint oil with low menthol content – Experimental study and simulation analysis for the recovery of piperitenone

• CO2 separation of piperitenone and 1,8-cineol in peppermint oil was investigated.
• Gas loading and selectivity was studied experimentally at different conditions.
• Semi-continuous fractionation was performed at 313 K and 85 bar.
• Countercurrent fractionation of key components was simulated and analyzed using GC-EOS thermodynamic model.
• Best fractionation was predicted at 313 K and 95 bar in a 10-stage column.

Low-menthol or dementholized oils can be regarded as potential sources of biocidal compounds, particularly monoterpenic ketones such as menthone, piperitone, piperitenone, pulegone and carvone. In this work, the recovery of piperitenone from peppermint oil by supercritical carbon dioxide fractionation is studied. Separation selectivity and gas loading measurements were performed in a semicontinuous high-pressure apparatus in order to evaluate the effect of temperature and solvent density on these properties. Semicontinuous fractionation was also carried out at a fixed temperature (313 K) and pressure (85 bar), collecting and analyzing extract samples until a purified piperitenone raffinate was obtained. The phase behavior of the system was modeled and predicted with the group contribution equation of state (GC-EOS). Good agreement with the experimental results was obtained. Finally, a continuous countercurrent multistage fractionation process was simulated, based on the GC-EOS model. The effect of operation temperature and pressure, solvent-to-feed ratio and reflux ratio was studied for different purity and recovery requirements and oil feed compositions.

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