Browsing by Author "del Valle, Jose Manuel"

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    An experimental methodology to validate the use of hydroethanolic mixtures as suspending medium / modifier for the supercritical CO2 extraction of suspensions
    (2025) Mamani, Marco Antonio; del Valle, Jose Manuel; Aravena, Paulo; Canales, Roberto
    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 degrees 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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    Application of Response Surface Methodology to Supercritical CO2 Extraction: Case Study on Coextraction of Carotenoids and Oil from Rosehip Shells and Seeds
    (2023) Uquiche, Edgar; Arias, Julian; del Valle, Jose Manuel
    Response surface methodology (RSM) is an experimental strategy widely used as a research tool in investigation. We reviewed 89 papers that used RSM to study the extraction of oils or minor lipids, using supercritical (SC) CO2, and observed that most of these studies have not contributed to an understanding of the extraction phenomenon, by neglecting prior knowledge on mass transfer or equilibrium relationships. We used the extraction of carotenoids from rosehip shells and oil from the seeds, as a case study to illustrate an improved strategy to apply RSM to oil-aided SC-CO2 extraction of high-molecular-weight nonpolar solutes, such as carotenoids. We selected the temperature and density to characterize the effect of solvent conditions, the specific CO2 consumption to characterize the interaction of solvent time and solvent power, and the percentage of seeds in the composite substrate to characterize the cosolvent effect of the oil. A rotatable central composite design was applied sequentially in three blocks, where the third block allowed incorporating quadratic coefficients to adequately describe the non-linear behavior of the responses.