Al-Darmaki, Naeema Ibrahim Karam (2012)
Ph.D. thesis, University of Birmingham.
Currently the extraction of valuable components from oils is of growing interest. Palm fatty acid distillate is a by-product from palm oil refining process which contains valuable minor components. The scope of the present work was to investigate the enrichment of high value low concentration components of palm fatty acid distillate namely squalene (1.8-2.3 wt.% squalene) using supercritical carbon dioxide as solvent with counter-current packed column kept under isothermal and longitudinal thermal gradient. The overall objective of this work was to explore the effect of extraction process parameters such as pressure, temperature, and solvent to feed ratio to optimize the conditions that lead to high separation efficiency. This work has been centred on the study of the solubility of the main lipid components in supercritical carbon dioxide, isothermal counter-current extraction, longitudinal thermal gradient fractionation and the effect of feed concentration. Solubility studies have been conducted for binary, ternary and quaternary systems as function of state of conditions through the application of a dynamic method. Binary systems of CO2/squalene, CO2/oleic acid, CO2/\( \alpha \)-tocopherol, and CO2/pseudo-component palm olein were measured at temperatures of 313, 333 and 353 K, and at a pressure range of 10 to 30 MPa. A ternary system of CO2/squalene/palm olein and a quaternary system of CO2/squalene/ palm olein/ oleic acid were also investigated at 313 K and pressures of 10 to 25 MPa. Comparison of the ternary system with the binary system showed a decrease in the solubility of squalene, with a corresponding rise in the solubility of palm olein. In the quaternary system, the presence of oleic acid decreased the selectivity of squalene. Extraction of squalene has been carried out on a counter-current glass beads packed column with the dimensions of 11.45 mm internal diameter and 1.5 m of effective height. The pressure and temperature were the operating conditions investigated and they varied from 10 – 20 MPa and 313 – 353K, respectively. Experimentation has demonstrated that squalene high fraction is achievable, however, squalene recovery has been found to be highly dependent on the extraction pressure and temperature. Squalene and free fatty acids content in the extract increased, and triglycerides content decreased during most of the fractionation runs. Longitudinal thermal gradient profiles along the column were investigated for further recovery of squalene, results showed the highest squalene recovery of more than 95% was reached and concentration of squalene was increased from 2wt% in the feed to 16wt% in the top product.
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