Ternary Phase Equilibria of the Sclareol-Ethyl Lactate-CO2 System and its Application in the Extraction and Isolation of Sclareol from Clary Sage
No Thumbnail Available
Files
Date
2009-02-11
Authors
Journal Title
Series/Report No.
Journal ISSN
Volume Title
Publisher
Abstract
The purpose of the research is to develop an environmentally responsible process to extract sclareol from Salvia sclarea L., more commonly known as Clary Sage. Sclareol is a highly water-insoluble plant natural product that is used as a fragrance in cosmetics and as a synthon for preparation of Ambrenolide odorants in perfumery. In addition, it is characterized as an antioxidant and has recently been studied for its cytotoxic and cytostatic effects against human leukemia cell lines. In these studies, sclareol was found to induce cancer cell cycle arrest and apoptosis. Moreover, sclareol is said to promote a calming effect on the nervous system and has been reported to relieve muscle spasms and menopausal symptoms.
In this work we studied the use of a GRAS solvent, ethyl lactate, as a solvent for sclareol, followed by the use of CO2 as an antisolvent for precipitation. We also studied the use of mixtures of ethyl lactate and CO2, followed by the use of water as a liquid antisolvent for sclareol precipitation. The solubility behavior of pure sclareol in ethyl lactate at various temperatures and in the mixture of ethyl lactate and CO2 at various temperatures and pressures was investigated. The finding suggested that ethyl lactate was capable for dissolving high concentration of sclareol at ambient temperature. Moreover, the generated ternary phase behavior of the sclareol-ethyl-lactate CO2 systems using a static synthetic method indicated the slight cybotactic effect. CO2 acted as a co-solvent to ethyl lactate at lower pressure and/or lower CO2 concentrations and as an anti-solvent at higher pressure and/or higher CO2 concentrations. The ability of the Peng-Robinson EOS with Vidal and Michelsen mixing rules model to predict the complex three-component phase behavior of this system is discussed, together with the implications of the thermodynamic behavior of the system on process design.
The generated ternary phase diagrams provided essential information for designing the extraction process. The extraction with ethyl lactate, followed by gas antisolvent (GAS) precipitation with CO2 faced some challenges, such as the need for evaporating a large amount of organic solvents, low sclareol precipitation yield, and low sclareol selectivity. The extraction with a mixture of ethyl lactate and CO2, on the other hand, is promising. By adjusting the ethyl lactate ratio in the extraction mixture, the extraction process could achieve high sclareol yield and relatively high sclareol purity. This process eliminated some problems occurred in the earlier process.
The liquid extract with the highest purity from CO2-ethyl lactate extraction was subjected for the purification and recovery processes. Activated carbon was used to remove some contaminants, such as plant pigments, terpenes, polyphenols, waxes, wax esters, etc., in the liquid extract. Afterward, the sclareol in the purified extract was recovered via a liquid precipitation, i.e. using water as the antisolvent for sclareol. The effect of the extract purity on the phase behavior of the mixture upon addition of water is discussed. Overall, the purification with the activated carbon at varied concentrations, followed by recovery of sclareol via water antisolvent process obtained products with reasonably high sclareol purity, ranging from 78 to 97 % (w/w).
Description
Keywords
precipitation, GRAS solvents, nutraceutical, activated carbon, Clary Sage, sclareol, extraction, gas antisolvent (GAS), liquid antisolvent
Citation
Degree
PhD
Discipline
Chemical Engineering
