Solubility of Triglycerides in Supercritical Carbon Dioxide.
Thesis DisciplineChemical Engineering
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
The solubilities of four saturated, mono-acid triglycerides: Trilaurin, Trimyristin, Tripalmitin and Tristearin have been determined in supercritical Carbon Dioxide, at 35, 40, 47 and 55°C and at CO2 densities of 0.57, 0.66, 0.73, 0.78, 0.84 and 0.89 g.cm-3. These solubilities were reproducible to within 10% and agreed well with those of a previous worker, in the mid-to-high density range. The experimental data were correlated using several theoretical and empirical methods. Of the empirical methods, regression of the triglyceride solubility data against a linear function of temperature and density was found to give the least mean square deviation. When a suitable functional form was used for the binary interaction parameter, the Carnahan Starling modification to the van der Waals equation of state was the most satisfactory theoretical correlation tested. A new experimental apparatus to determine solubilities in supercritical fluids was designed and constructed. The design featured the particular advantage that a microsampling technique using direct coupling to an HPLC apparatus was used to take samples of the high pressure saturated CO2 stream. This obviated problems due to depressurisation of the outlet stream. Carbon dioxide was chosen to be the solvent for its low critical properties, low toxicity and ready availability. The triglycerides were selected as solutes for their relevance to the Dairy and Food Industries. During the course of this work literature references to solubility data since 1982 were compiled.