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Thesis (PhD)--University of South Australia, 1997

Thesis (M.S.)--Virginia Polytechnic Institute, 1965. / Vita. Abstract. Includes bibliographical references (leaves 34-36). Also available via the Internet.

Thesis (Ph. D.)--Oregon Graduate Institute of Science and Technology, 1997.

Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 99-102).

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains xi, 144 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 91-93).

Thesis (MTech (Chemical Engineering))--Cape Technikon, 2002. / The high purity 1-octene produced by Sasol Alpha Olefins in Secunda and which is sold to DOW Chemical Company for co-monomer application, has performed poorly over the DOW Ziegler-Natta catalysts. The reason for the poor performance was catalyst poisoning caused by low-level impurities present in the 1-octene. Much work from Sasol and DOW has gone into identifying the components responsible for catalyst deactivation, as well as methods suitable for removing them without significant 1-octene losses. Super NMP (n-Methyl-2-Pyrrolidone) extractive distillation piloting was performed previously on 1-octene in order to remove the low-level impurities that deactivate the DOW catalysts. VLE (vapour liquid equilibrium) test work performed previously indicated that all xylenol isomers are more promising as extractive distillation solvents than NMP.

The application of bidentate N,N'-donor ligands, such as 2,2'-biimidazole (BIIMH2) and 2,2'-pyridylimidazole (PIMH) and (1H-benzimidazol-2yl)-N-methylmethanamine (BIMAH), in the solvent extraction of base metal ions from an acidic sulfate/sulfonate medium was investigated. PIMH and BIMAH showed selectivity for Ni(II) with the only interfering ion being Cu(II) in the pH range 1.2-1.8 but BIIMH2 lacked selectivity. The extraction patterns observed were influenced by stereochemical aspects, and this agreed well with the envisaged design of nickel(II)-specific extractants through stereochemical “tailor-making” which is proposed in this study. The extraction patterns were explained from a coordination chemistry point of view using spectroscopic analysis and single crystal X-ray analysis to diagnose the geometry of the complexes formed from the interaction of the base metal ions with the ligands. The formation of the trigonal bipyrimidal [Cu(PIM)2(H2O)](SO4) complex, with a water molecule coordinated, while nickel(II) forms a square planar bisPIMH was put forward as the reason for extraction pattern observed with this ligand. Cobalt(II) also forms a bisPIMH complex but has two water molecules coordinated in the formation of a distorted octahedral complex, and this results in less extractable species. A similar observation as for PIMH was noticed in BIMAH complexation reactions. The BIIMH2 complexes were found to be distorted octahedral, through the bis-coordination of BIIMH2 and two sulfonate ions, resulting in lack of pH-metric separation of the later 3d metal ions. The stability constants data was in agreement with what was observed in the solvent extraction and coordination chemistry studies for the three ligand systems.

An experimental investigation was undertaken to study the factors affecting phase separation in a specially constructed, laboratory scale mixer-settler. Two phase systems were used: 1. A laboratory prepared HSLIX64N-copper phase system, similar to that used in commercial copper solvent extraction processes. 2. A phase system obtained directly from the uranium extraction circuit of the Key Lake Mining Corporation, Sask., millsite. A settler scale-up criterion relating dispersion band thickness to specific settler flow of dispersed phase, was found to have considerable merit. Besides being dependent on specific settler flow, the dispersion band thickness was found to be a function of the phase ratio (for system 2 only), dispersion introduction level (for system 2 only), and temperature. Mixing intensity had no appreciable effect with either system. Microscopic examination of the dispersion produced with system 2 revealed the existence of double dispersions; that is, drops within drops. A photomicroscopic technique was used to undertake a drop size investigation of the dispersion produced with system 2. Drop size was found to be independent of dispersion throughput, a weak function of impellor speed and a relatively strong function of the phase ratio. With the exception of organic continuous operation with system 1, it was possible, based on the holdup and drop size profile within the dispersion band, to distinguish two horizontal sublayers within the dispersion band. In the "even concentration sublayer", comprising the majority of the dispersion band, the holdup and average drop size is nearly constant throughout. In the "dense concentration sublayer", both the holdup and the average drop size increase sharply as the coalescence front is approached. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

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