Supercritical fluid extraction from Priprioca: Extraction yield and mathematical modeling based on phase equilibria between solid and supercritical phases

• Priprioca extract were obtained by SFE at 40 and 50 °C and 100, 200 and 300 bar.
• At a pressure of 100 bar, the extraction yield increased with increasing temperature.
• At 200 and 300 bar, the extraction yield decreased with increasing temperature.
• A new model was proposed to model the SFE kinetics.
• A novel method was proposed to calculate the distribution coefficient of the solute between CO2 and the solid phase.

This study aimed to investigate the supercritical carbon dioxide extraction of Cyperus articulatus L. (Priprioca). Before the experiments were performed, the raw material was cleaned, vacuum packed and maintained at −5 °C. The moisture content of the material was determined using an oven with forced air circulation operating at 105 °C. The material was then ground, and the mean diameter of the resulting particles was determined using a set of standard sieves. Extraction was performed at pressures of 100–300 bar, temperatures of 40–50 °C, and extraction times up to 240 min using supercritical carbon dioxide as the solvent. For each load, approximately 50 g of Priprioca was packed into the extractor. According to the experimental results, the yields of extraction were significantly influenced by pressure and temperature. Additionally, this paper provides a mathematical model of the supercritical extraction of Priprioca. The employed mathematical model was based on the mass conservation law, which included two partial differential equations for the solute concentration in the solid and fluid phases. By applying a novel method, the distribution coefficient of the extract between supercritical fluid and solid phases was obtained using the criterion of equal fugacity at equilibrium. The model-predicted extraction yield was then compared with the corresponding experimental data. Additionally, the reasons for the deviations between the model and the experimental data under certain operational conditions are discussed.

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