abstract
This work evaluated the solubility of caffeic acid (CA) in mixtures of supercritical carbon dioxide (scCO(2)) and ethanol at different temperatures (313, 323 and 333 K), pressures (20, 30 and 40 MPa) and concentrations of ethanol (2.2, 5.4 and 10.2 mol%). The Soave-Redlich-Kwong and Cubic Plus Association (CPA) equations of state were used to correlate the binary mixture data and to predict the ternary system data. CA solubility in ethanol is approximately 106 times higher than its solubility in pure scCO(2). By using 10.2 mol% ethanol in scCO(2), CA solubility increased 30,000 times at 313 K and 20 MPa. Both models provided reasonable descriptions of the experimental data for the binary systems. However, CPA-EoS can better describe the strong interactions between acid molecules and ethanol, and can predict that the addition of small amounts of ethanol to scCO(2) provides a large increase in CA solubility.
keywords
SUPERCRITICAL CARBON-DIOXIDE; EQUATION-OF-STATE; PHENOLIC-COMPOUNDS; PLUS ETHANOL; ASSOCIATING SYSTEMS; PHASE-EQUILIBRIA; VAPOR-PRESSURE; FERULIC ACID; WATER; COSOLVENT
subject category
Chemistry; Engineering
authors
Bitencourt, RG; Palma, AM; Coutinho, JAP; Cabral, FA; Meirelles, AJA
our authors
André Palma
Post-Doc Fellowship
acknowledgements
In Brazil, this work was financially supported by CAPES, FAEPEX (Project number 2781/2017, 519.292), FAPESP (Project number 2010/16665-3 and 2014/21252-0) and CNPq (Project numbers 406856/2013-3, 305870/2014-9, 303734/2016-7 and 406963/2016-9). In Portugal, this work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145- FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement.; Andre M. Palma acknowledges KBC for his PhD grant and Raphaela G. Bitencourt thanks CNPq (140345/2014-0) for her scholarship.