Thesis (MScEng)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 66-70). Also available on the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Thesis (Ph. D.)--Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2008. / Koros, William J., Committee Chair ; Breedveld, Victor, Committee Member ; Jones, Christopher W., Committee Member ; Kumar, Satish, Committee Member ; Nair, Sankar, Committee Member.

Thesis (M.S.)--Humboldt State University, 2007. / Includes bibliographical references (leaves 81-82). Also available via Humboldt Digital Scholar.

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In this dissertation the power draw, the mass transfer and the liquid mixing behaviour of boiling and hot sparged stirred tank reactors (STRs) were investigated. The power draw characteristics of six different impellers were studied under varying operating conditions and expressed in terms of the relative power draw, RPD. Generally the impellers showed considerably higher power draw in hot gassed than in comparable cold conditions. The main phenomenon in hot systems, the evaporation of liquid into a gas bubble suddenly exposed to it, was investigated experimentally. The growth of nitrogen and air bubbles in hot water was found to be very fast and be completed typically within milliseconds after their exposure to the liquid. This was confirmed by studies applying acoustic bubble sizing techniques which were carried out together with Richard Manasseh from CSIRO, Melbourne, Australia. Experimental studies of the gas-liquid mass transfer in hot sparged STRs were carried out using a tank of 450 mm in diameter agitated by a 180 mm Rushton turbine. Experiments involving the temperature kinetics in an air-water system and absorption and desorption of ammonia were used to determine gas and also some liquid side mass transfer coefficients. The gas side coefficients kga were found to be typically in the order of 0.01 s-1. An enhancement of the liquid side mass transfer was also observed. Both Fick and Stefan-Maxwell models were employed to express gas side mass transfer coefficients. The models predict there will be a decrease of the coefficients at high concentrations. In the hot sparged tank the temperature is essentially uniform throughout the STR. Liquid mixing times have been measured for various boil-off and sparging rates. No significant deviations from the single phase or the cold gassed mixing times in this equipment were recorded.

The work presented in this thesis has focused on the development and implementation of two-dimensional (2D) nuclear magnetic resonance (NMR) correlation techniques to unambiguously discriminate and characterise competitive adsorption and mass transfer processes in porous materials. This has primarily involved investigations on porous oxides; in particular silicas and aluminas commonly used as catalyst supports. The techniques used are demonstrated to be capable of acquiring information relevant to the performance of heterogeneous catalysts and adsorbents across the hierarchy of length scales relevant to industrial processes. The methodologies associated with the acquisition and processing of 2D NMR correlation data were first established through the development of analytical models capable of simulating 2D signal attenuation data for T1-T2, D-T2 and T2-T2 experiments. Common artefacts were also discussed by means of experimental and simulated examples and, where appropriate, methods have been introduced for their prevention. The NMR relaxation behaviour of water saturating the pore space of silica was observed to correlate strongly with independent measurements of the activation energy of dehydroxylation, thus establishing NMR relaxometry as a tool for directly probing the surface energetics of silica surfaces. This interpretation of T1/T2 ratios differs from that in conventional applications of the technique which typically present the ratio as an indicator of surface-adsorbate interaction strength. Here, the T1/T2 ratios of three liquid probe molecules: ethanol, diethyl ether and cyclohexane, are used to investigate the influence of pore size and density of adsorption sites on relaxation behaviour. Competitive adsorption behaviour has been directly investigated through the acquisition of T1-T2 correlation data of binary liquid mixtures imbibed in various silica supports. These measurements, in combination with a newly developed model for the relaxation of multi-component mixtures, have provided a comprehensive assessment of the ability of this technique to quantify intra-pellet compositions and address competitive adsorption behaviour in porous media. With the aid of a random walk Monte-Carlo model to simulate transverse relaxation in packed bed reactors, T2-T2 relaxation exchange measurements have been used to investigate mass transfer across the fluid-solid boundary in a packed bed reactor filled with γ-alumina and liquid cyclohexane. These data were used to quantify the rate of exchange between intra- and inter-pellet environments at a number of flow rates. Exchange rates were then converted into the more convenient terms of mass transfer coefficients and compared against literature data using two separate dimensionless mass transfer analyses.

Despite being the subject of peer reviewed research since the mid-1980s, the conservative nature of the wastewater treatment industry means that the commercial application of membrane aerated biofilm reactors has not realized the potential that the published research demonstrates. The early research demonstrated the ability of membrane aerated biofilm reactors to achieve good levels of pollutant removal from various types of wastewater, but also exposed several weaknesses of the technology (i.e. cost of membranes, control of biofilm thickness) which have prevented the concept of MABfRs being developed in viable wastewater treatment technologies. However, as membrane technology has developed, the cost of suitable membranes has fallen, prompting the research community to revisit the concept. This later batch of research has identified several niche applications where membrane supported biofilms can be used for effective removal of pollutants from water. Using the MABfR for the treatment of secondary effluent as a polishing step is another niche application which has been identified and is examined in this work; leading to the development of a patented treatment technology – the BioSettler.

Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2009 / The main purpose of this study was to quantify the growth and oxygen mass transfer kinetic parameters of the filamentous bacterium Streptomyces coelicolor, immobilised on the external surface of a ceramic membrane in a continuously operated pressurised Membrane Gradostat Bioreactor (MGR). One of the most important and critical parameters required when studying biofilms, are the growth kinetics, as they can be utilised to model both the mass transfer and biological reactions occurring within the biofilm. Single fibre MGR's (SFMGR) were operated using a pneumatic system to supply humidified pressurised air to the extra capillary space (ECS) and pressurised growth medium to the lumen of the ceramic membrane. Two growth media; a complex growth medium, ISP2, and a defined growth medium, were tested and supplied to the lumen of the ceramic membrane in the dead-end mode