An experimental methodology to validate the use of hydroethanolic mixtures as suspending medium / modifier for the supercritical CO2 extraction of suspensions

• Published in: The Journal of supercritical fluids Vol. 216; p. 106423
• Main Authors: Mamani, Marco Antonio, del Valle, José Manuel, Aravena, Paulo, Canales, Roberto
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-02-2025
• Subjects: Aqueous ethanol; Extraction; Modifier; Steady-state conditions; Supercritical CO2; Suspensions; Aqueous ethanol; Steady-state conditions; Extraction; Modifier; Supercritical CO2; Suspensions
• ISSN: 0896-8446
• DOI: 10.1016/j.supflu.2024.106423

We developed a methodology to study the extraction of high-value solutes directly from suspensions of finely disrupted substrates. For that, we modelled the high-pressure phase equilibrium for the ternary (CO2 + ethanol + water) system using experimental literature data. Different compositions of hydroethanolic mixture and CO2 were loaded into an extraction vessel set at 30–35 MPa and 40–50 °C during static extraction, and a gaseous mixture with the composition of the CO2-rich gaseous phase in the extraction vessel was continuously fed during dynamic extraction. Losses of the fed hydroethanolic mixture occurred mainly during dynamic extraction (10–30 wt%) and were properly distributed to account for actual flows and compositions of experimental streams. Mostly, equilibrium conditions were reached following about 1 h of the 2-h dynamic extraction, and good reproducibility was achieved. In conclusion, equilibrium is reached in which two phases coexist in equilibrium within the extraction vessel: a water-rich liquid phase and a CO2-rich gaseous phase.
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•PC-SAFT model for the high-pressure phase equilibrium of (CO2 + ethanol + water).•Extraction of suspensions with aqueous-ethanol-modified CO2 is a two-phase process.•Solutes present in a water-rich phase are transferred to a flowing CO2-rich phase.•∼40 min equilibration when feeding extractor with solvent mix like gaseous phase.•Steady-state amounts and compositions of phases after depressurization measured.