Načrtovanje visokotlačne separacije maščobnih kislin iz rastlinskih olj : doktorska disertacija

slovenian

doktorska dela

2014

Univerza v Mariboru, Fakulteta za kemijo in kemijsko tehnologijo

This research work presents phase equilibria, extraction and fractionation of fatty acids in vegetable oils enriched with free fatty acids (FFA) at high pressures in an inert medium such as carbon dioxide (CO2). This data is the key for further planning of high-pressure separation processes, helping to improve certain industrial processes towards environmental protection and product quality. The literature already reports on phase equilibria for the system vegetable oil - CO2 for pressures ranging up to 350 bar, whereas for higher pressures less data is available. Also, at these pressures little has been reported on the phase inversion of these systems. In our experiments, three commercial vegetable oils, namely rapeseed oil, corn germ oil, and borage oil were used. For enrichment of oils with FFA the saponification process was used. Measurements of phase equilibria and observations of phase inversions were performed on the systems FFA-enriched rapeseed oil - CO2, FFA-enriched corn germ oil - CO2, and FFA-enriched borage oil - CO2 in the pressure range between 100 and 550 bar and temperatures 35, 45, 65, and 85 °C. Fatty acid content was determined by gas chromatography and based on the obtained results the distribution coefficients and separation factors were determined. Research on high pressure extraction of oil from seeds with CO2 was performed on two natural materials with a high content of free fatty acids, namely the seeds of borage (Borago officinalis L.) and the seeds of evening primrose (Oenthera biennis L.) at a pressures 200 and 300 bar and temperatures 40 and 60 °C. Extraction curves were evaluated using two mathematical models that best describe the course of the extraction curve, namely in the region of constant extraction rate and in the region of unsteady mass transfer. The final research represents fractionation of rapeseed oil in order to isolate gamma-linolenic acid and to concentrate FFA and beta-sitosterol in oil. Concentrating of FFA was performed with two stage supercritical CO2 extraction. In comparison to the conventional method of column chromatography two stage supercritical extraction gives satisfactory results.

07.08.2023