Supercritical CO2 recovery of caffeine from green coffee oil: new experimental solubility data and modeling

Abstract

The caffeine solubility in supercritical CO2 was studied by assessing the effects of pressure and temperature on the extraction of green coffee oil (GCO). The Peng-Robinson¹ equation of state was used to correlate the solubility of caffeine with a thermodynamic model and two mixing rules were evaluated: the classical mixing rule of van der Waals with two adjustable parameters (PR-VDW) and a density dependent one, proposed by Mohamed and Holder² with two (PR-MH, two parameters adjusted to the attractive term) and three (PR-MH3 two parameters adjusted to the attractive and one to the repulsive term) adjustable parameters. The best results were obtained with the mixing rule of Mohamed and Holder² with three parameters

Effect of cosolvents (ethyl lactate, ethyl acetate and ethanol) on the supercritical CO 2 extraction of caffeine from green tea

“…Due to the lack of experimental solubility data of caffeine in the CO 2 +EL and CO 2 +EAC supercritical solvents, the solubility (Y*) was estimated as the slope of a theoretical linear behavior of the OEC between t = 0 and t = 14 min (Table 4). For comparison, the estimated caffeine solubility in pure CO 2 was 0.029 % mass, which is quite in agreement with the experimental solubility measured at 343 K and 28.1 MPa (0.023 % mass) [35]. These estimated solubilities presume that, as in the case of the solubility of caffeine in the liquid solvents [30,31], the solubility of caffeine in CO 2 with ethyl lactate cosolvent is higher than in the case of ethanol or ethyl acetate cosolvents.…”

Extraction of Andrographolide from Andrographis paniculata Dried Leaves Using Supercritical CO2 and Ethanol Mixture

“…This effect of pressure can be explained by the increment of SCF density. A number of researches have proven that the solubility of a solute increases with the increase in supercritical solvent density. − Tan and Liou found that the desorption activation energy was lower at higher pressure and became proof that regeneration of activated carbons using supercritical CO 2 at higher pressures are more favorable . In this regard, the desorption may be more convenient to occur at a higher operating pressure or higher fluid density.…”

Recovery of spent coffee grounds oil using supercritical CO2: Extraction optimisation and physicochemical properties of oil

“…Several researcher groups have investigated the application of supercritical CO 2 extraction to spent coffee ground byproducts for polyphenols extraction (Ahangari & Sargolzaei, 2013;Andrade et al, 2012;de Azevedo et al, 2008). However, to date, there are no literature reports on the optimal process variables for the supercritical CO 2 extraction of oil from spent coffee grounds and its physicochemical properties, using a Box-Behnken experimental design.…”