@phdthesis{Dasgupta2017, author = {Dasgupta, Sunanda}, title = {Metastable zone determination and nucleation kinetics during melt crystallization of poly-unsaturated fatty acids}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-44175}, school = {BTU Cottbus - Senftenberg}, year = {2017}, abstract = {The range of application of fatty acids is as broad and varied as the diverse kinds of fatty acids themselves, stretching from bulk scale productions as in the case of biodiesel or lubricant manufacturing over consumer or end products like cosmetics, medicinal or nutritional additives to relatively smaller scale specialty chemicals like epoxy resins, insect repellents and so on. The crystallization temperatures of the unsaturated fatty acids are much lower than those of the saturated ones, which is an important and desirable property for raw materials such as in the production of epoxy resins. Separation and purification of these enriched unsaturated fatty acid fractions depending on their applications is mainly performed by two thermal fractionation processes, namely, distillation and crystallization. The potential behind the success of purification of these multi-component organic fatty acid mixtures with the help of melt crystallization, apart from the fact that it is cost effective owing to the obvious reduction of solvent removal and regeneration steps, is that of the relatively large differences in the melting points of the individual fatty acids. A detailed and fundamental understanding of the crystallization especially nucleation kinetics of a variety of vegetable oil based fatty acid mixtures has been provided in this work. It also describes the solid-liquid phase diagrams of these poly-unsaturated mixtures including their metastable zone widths of nucleation and solidification. This theoretical part of this thesis is a detailed resource on the global production and application of vegetable oils and their derivatives. A clear mathematical and physical road map for the application of the Fisher Turnbull model to calculate the enthalpy values starting from the very basic supersaturation equation has been established and extensively explained as well. Nucleation studies have been carried out on various reactor setups in micro-, milli- and liter-scale. It successfully models the induction times of nucleation as a function of supercooling at different cooling rates both in micro and macro scale. 3D modeling of this parameter to see the combined effects of temperature and in turn viscosity have also been successfully implemented on the milliliter scale results, as more of the bulk nucleation phenomenon was observed in the latter. Fisher Turnbull plot and the Gibbs Thompsons model were adjusted and applied to correlate the Gibbs free energy, involved with the rate of nucleation captured by the FBRM™ (Focused Beam Reflectance Measurement) technology. The scope of this measurement technology was also tested in liter scale. The results showed that FBRM technology is applicable when the solution is relatively dilute and does not have too many overlapping crystals.}, subject = {Metastable zone; Fatty acid; Nucleation kinetics; Melt crystallization; FBRM; Metastabil Bereich; Mehrfach unges{\"a}ttigte Fetts{\"a}ure; Keimbildung Kinetik; Schmelzkristallisation; FBRM; Polyenfetts{\"a}uren; Keimbildung; Kinetik; Schmelzkristallisation; Metastabilit{\"a}t}, language = {en} }