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Title:	Behaviour of aqueous solution, crystallisation and characterisation of L-Isoleucine
Authors:	Nornizar Anuar (P31658)
Supervisor:	Wan Ramli Wan Daud, Prof. Dato' Dr.
Keywords:	Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia Crystallization Crystallization -- Mathematical models Separation (Technology)
Issue Date:	27-Aug-2012
Description:	The motivation to seek for the relationship between liquid and solid system of crystallising solution is the reason this research is established. To achieve this objective, the studies of chemistry of L-isoleucine in solution, kinetic of L-isoleucine crystallisation process, and the product crystal chemistry were carried out. The slow cooling batch crystallisation and solubility study experiments were conducted in a 250 mL batch reactor, while the characterisation of product crystals was carried out by using analytical equipments. The effect of additives, namely L-leucine and L-valine to solution chemistry, crystallisation and product crystal of L-isoleucine was also investigated. Molecular modelling techniques to simulate the morphology of Lisoleucine and behaviour of single and clustered molecules in the solution prior to crystal growth were also adopted. The finding of solubility data is consistent with the existence of two polymorphic forms (form A and B), in which both forms have different solubility and enantiotropically related. Thermodynamics properties generated from solubility data were also presented and discussed. The polymorphs of L-isoleucine and the new crystalline phase (recovered from the isoleucine-additive mixture solution), were characterised using optical microscopy, DSC, XRPD and FTIR microscopy confirmed this polymorphic behaviour. The XRPD analysis confirmed that the crystals recovered from Ile-additive mixture are solid solutions. Lleucine was found to be more prone to form solid solution with L-isoleucine, than to L-valine with L-isoleucine. Polythermal crystallisation kinetic studies revealed that the crystallisation temperature increases with cooling rate and solute concentration, which results in a decrease of the MSZW with decreasing cooling/heating rate. The study also revealed that cooling rates affect the polymorph formation, where at cooling rates of 0.25 - 0.75oC/min, form B is formed, whilst a more stable polymorph A can be recovered at cooling rate 0.10oC/min. Isothermal study showed that for high supersaturation system, the critical cluster radius, r* are between 5 - 17 Å, associated with between 3 - 121 molecules, (N*) and for low supersaturation system, r* value is between 3 - 14 Å and NewsArticle.err between 1 - 64. For pH range of 5.1 - 6.3, and temperature range between 10 and 80oC, zwitterion species of L-isoleucine has remain as dominating species in both solubility and crystallisation study. Meanwhile, the presence of L-leucine in L-isoleucine solution suppresses the primary nucleation of Lisoleucine, while L-valine in the solution enhances the solution's crystal nucleation. The molecular modelling technique adopted in this study shows that the simulated morphology and the calculated lattice energy (-66.01 kcal/mol) are in good agreement with experimental data. Modelling studies of the L-leucine as an additive to Lisoleucine reveals that the preferential sites of the crystal habit surfaces of Lisoleucine where the most preferred additive binding sites are on (110) and (110) facets, and in excellent agreement with experimental data. The single molecule conformational search of L-isoleucine has proven that it has the capability to form polymorphs. The study of cluster energy, packing density and torsional change of relaxed clusters have shown the possibility that, cluster size with 50 molecules, is the intersection point for the change of polymorphic formation of L-isoleucine crystal. The variance statistical analysis adopted in this study has shown that torsion angle, T1 might be the responsible rotation that causes the polymorphic formation phenomenon in L-isoleucine.,Certification of Master's / Doctorial Thesis" is not available
Pages:	207
Call Number:	TP156.C7N646 2012 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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