Browsing by Author "Aravena, Paulo"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    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.
  • No Thumbnail Available
    Item
    Influence of Hydrogen Bond Acceptors and Water Content on Surface Tension in Glycol-Based Eutectic Mixtures
    (2024) Aravena, Paulo; Cea-Klapp, Esteban; Gajardo-Parra, Nicolas F.; Olea, Andres F.; Carrasco, Hector; Matias Garrido, Jose; Canales, Roberto I.
    One of the environmental concerns in the chemical industry is using organic solvents that are not environmentally friendly. Eutectic mixtures, also called deep eutectic solvents (DESs), have emerged as their substitutes due to favorable properties, including biodegradability, tunability, and low cost, among others. DESs show applications in extractions, biocatalysis, etc. To expand their uses, it is crucial to characterize their properties and understand their interactions with other solvents. In this study, the surface tension of DESs between 30 and 60 degrees C at 101.3 kPa was measured. The DESs were prepared using choline chloride or betaine as the hydrogen bond acceptor (HBA) and a glycol (ethylene glycol, 1,2-propanediol, 1,3-propanediol, or 1,4-butanediol) as the hydrogen bond donor (HBD) in different molar ratios. The surface tension of DESs + water mixtures was measured over the entire range of compositions. To assess the effect of temperature, HBD chain length, and water content, PC-SAFT coupled with the density gradient theory was used to model the surface tension. Furthermore, molecular dynamics simulations were conducted to gain a molecular understanding of the components at the interface. The molecular insights obtained from these simulations and the experimental data can help reduce the number of experiments when designing DESs for chemical processes.