MgCl2 brines present a number of potential advantages for the processing of saprolite ores for nickel production. Concentrated MgCl2 solutions enhance the activity of acid used, allow atmospheric leaching at elevated temperature and inhibit magnesium dissolution, which reduces acid consumption and increases metal selectivity. However, with a chloride system it is economically requisite to recover hydrochloric acid, conventionally accomplished by pyrohydrolysis. This work was performed in conjunction with a novel flowsheet for the processing on saprolite ores, which recovers HCl by the precipitation and subsequent decomposition of magnesium hydroxychlorides, alleviating some of the issues with pyrohydrolysis. Leaching and iron control experiments have been conducted in concentrated MgCl2 brines, up to 4.5 m, to determine the most amenable process conditions. It was determined that > 95% extraction of metals was possible using both aqueous and gaseous HCl. In addition, the feasibility of iron control by precipitation with MgO addition was proven.

An electrochemical cell consisting of a flow-through yttria-stabilized zirconia (YSZ) sensor and a flow-through Ag/AgCl reference electrode has been employed to measure pH of high-temperature acidic sulphate solutions relevant to the pressure acid leaching (PAL) of nickel laterites. In a previous study, this cell was used to measure pH of H2SO4, Al2(SO4)3-H2SO4 and MgSO4-Al2(SO4)3-H2SO4 solutions at 250oC. In this work, the solutions range in complexity from the binary MgSO4-H2SO4, NiSO4-H2SO4, and Al2(SO4)3-H2SO4, through the ternary MgSO4-Al2(SO4)3-H2SO4 and NiSO4-Al2(SO4)3-H2SO4, to the PAL process solutions, whereas the temperature ranges from 200oC to 250oC. The measured and theoretical pH values typically agree within less than 0.1 pH unit and 0.2 pH units in synthetic solutions and PAL solutions, respectively. This is an improvement over the results of the previous study in synthetic solutions, which show differences between theory and experiment as high as 0.4 pH units. The conversion of measured potentials into pH values is based on the new mixed-solvent electrolyte (MSE) speciation model of the OLI Systems software calibrated independently based on solubility measurements. Both Henderson’s equation and the exact definition of the diffusion potential were employed in treating the obtained experimental data. Experimental pH values calculated using the diffusion potentials evaluated by either approach are essentially the same. This finding suggests that Henderson’s equation, which is based on readily available limiting ionic mobilities, can be effectively used. Lithium chloride is found to be a suitable alternative to sodium chloride as the reference electrode solution for the measurement of pH of aluminium-containing solutions, because it did not induce precipitation of aluminium as an alunite-type compound. The experimental results indicate that the high-temperature behaviour of Ni, Co and Mn sulphates can be satisfactorily approximated with that of MgSO4. The experimental findings also support the postulation that acid should be added to a PAL process so that the solution pH is around 1 at the leach temperature, regardless of the feed composition. The cell can be used for hydrometallurgical process research and development on a laboratory scale with very satisfactory performance, provided that a well-behaved YSZ sensor is available.

As of 2010, cancer remains the leading cause of death in Canada, and second in the United States of America. This is despite decades of research into development of chemotherapeutics and diagnostics. A number of major challenges have prevented new discoveries from translating into a reduction in mortality rates. One challenge is the poor efficiency with which anti-cancer agents (diagnostic contrast agents and therapeutics) reach deregulated cells in the body. Therefore, development of new methods and technologies for improving efficiency of delivery has been a focus of research. Nanoparticles are leading candidates for improving the efficiency of delivery because they can act as payload vehicles for anti-cancer agents, because it is possible to mediate their interaction with biological systems and thus their pharmaockinetics, and because they can exploit inherent vulnerabilities of tumours. This thesis describes the results from a series of research projects designed to progress our understanding of how nanoparticles behave in vivo, and how their design can be optimized to improve tumour targeting.

Catalytic supercritical water gasification (SCWG) is a promising technology for hydrogen and methane production from wet organic feedstocks at relatively low temperatures (e.g. <500 oC). However, in order to make this process technically and economically viable, solid catalyst with enhanced activity and improved hydrogen selectivity should be developed. In this study, different aspects of catalytic SCWG have been investigated. The performance of several supported-nickel catalysts were examined to identify catalysts that lead to high carbon conversion and high hydrogen yields under near-critical conditions (i.e. near 374 oC). Moreover, for the first time, the effects of several parameters which dominated the activity of the supported nickel catalysts have been systematically investigated. Among the several different catalyst supports evaluated at 5% nickel loading, α-Al2O3, carbon nanotube (CNT), and MgO supports resulted in highest carbon conversions, while SiO2, Y2O3, hydrotalcite, yttria-stabilized zirconia (YSZ), and TiO2 showed modest activities. Comparing the XRD patterns for the support materials before and after the exposure to supercritical water, α-Al2O3, YSZ, and TiO2 were found to be hydrothermally stable among the metal oxide supports. Using the same amount of nickel on α-Al2O3, the methane yield decreased by increasing the nickel to support ratio whereas the carbon conversion was only slightly affected. At a given nickel to support ratio, a threefold increase in methane yield was observed by increasing the temperature from 350 to 410 oC. The catalytic activity also increased by the addition small quantity of potassium. The activity of Ni/γ-Al2O3 catalyst varied based on the affinity of the catalyst to form nickel aluminate spinel. This is also the first report on the role of oxidative pretreatment of the carbon nanotubes by nitric acid on the performance of these catalysts for the supercritical water gasification process. Using different lignocellulosic feeds, it was found that the gasification of glucose, fructose, cellulose, xylan and pulp resulted in comparable gas yields (± 10%) after 60 min, whereas alkali lignin was substantially harder to gasify. Interestingly, gasification yield of bark, which had a high lignin content, was comparable to those of cellulose. In summary, the Ni/α-Al2O3 catalyst had a higher hydrogen selectivity and comparable catalytic activity to the best commercially available catalysts for SCWG of carbohydrates.

Treatment of cardiac diseases involves transplantation of donor hearts, since the damaged heart has limited self-regeneration potential. An alternative treatment option has emerged as engineered cardiac tissues, grown in vitro by cultivation of cardiac cells on biomaterials, have comparable properties to native myocardium and can be implanted for cardiac repair. Major current limitations are a viable cell source and adequate vascularization to support cell survival. In this thesis, two proangiogenic biomaterials, a scaffold and a hydrogel, were developed to achieve vascularization in vitro and in vivo for cardiac repair. Scaffold patches are suitable for repairing congestive heart failure or congenital malformations, while injectable biomaterials allow minimally-invasive treatment post-myocardial infarction (MI). In the first aim, a collagen scaffold with covalently immobilized vascular endothelial growth factor (VEGF) was developed, and improved cell mobilization, survival and proliferation when used for free wall repair in adult rats. This increased angiogenesis, which aided in retaining the biomaterial size to allow tissue growth. In the second aim, a collagen-chitosan hydrogel with encapsulated thymosin β4 (Tβ4) was developed to 1) recruit cells from the heart epicardium for repair post-MI in vivo, and 2) guide capillary outgrowths from arteries and veins to form oriented capillary structure for in vitro cardiac tissue engineering. Results showed that the encapsulation of Tβ4 into collagen-chitosan hydrogels led to cell outgrowths from rat or mouse cardiac explants in vitro. A portion of the recruited cells were CD31-positive endothelial cells (ECs) that formed tubes. The hydrogel was injected in vivo to increase vascularization and number of cardiomyocytes within the infarct area post-MI, which improved left ventricular wall thickness. Tβ4-hydrogel also promoted the outgrowth of capillaries from vascular explants that followed the direction of the hydrogel-coated grooves of a micropatterned polydimethylsiloxane (PDMS) substrate. These capillary outgrowths eventually formed a vascular bed for engineering vascularized cardiac tissues. This thesis presents two bioinstructive biomaterials with sustained and localized delivery of angiogenic molecules to be used for in situ cardiac repair based on improved vascularization. The use of cell-free bioactive materials overcomes limitations of cell isolation and expansion as required for cell therapies or implantation of engineered tissues.

Perchloroethene and trichloroethene are among the most persistent groundwater pollutants, and Dehalococcoides is the only known species that can degrade these compounds completely to non-toxic ethene. Characterization of the reductive dehalogenase (RDase) enzymes responsible for dechlorination is important to understanding this process. A series of dechlorination assays were performed with whole cell suspensions and cell-free extracts of three Dehalococcoides-containing mixed microbial consortia to compare dechlorination kinetics and to characterize co-contaminant inhibition. Michaelis-Menten kinetic parameters Vmax and Km, as well as non-competitive inhibition coefficients for 1,1,1-trichloroethane and 1,1-dichloroethane inhibitors are reported. Secondly, blue native gel electrophoresis was developed as a method to isolate active protein complexes containing RDases. Thirdly, sources of variability in the isotopic fractionation of vinyl chloride to ethene reaction step were examined using cell-free extracts and whole-cell suspensions. Understanding the function and range of RDases are goals towards the successful application of Dehalococcoides-containing cultures to remediate contaminated sites.

Stress corrosion cracking (SCC) susceptibility of the phosphorus de-oxidized copper has been evaluated in synthetic seawater polluted by sulfides using slow strain rate test (SSRT). The effect of concentration of sulfide, temperature, and applied cathodic and anodic potentials on the final strain values and maximum stress were also studied. No cracks were found under the tested conditions. The final strain and maximum stress values decreased but not significantly, with increase in the temperature, applied anodic potential and sulfide concentration. The observed effect is due to the section reduction by uniform corrosion. Lateral cross section and microscopic examination of the fractured specimen ruled out the existence of the localized corrosion. Electrochemical measurements showed that the Cu2S film is not a protective film and also exhibits a mass transfer limitation to the inward diffusion of the sulfides. Based on these results the reasons for the absence of cracking are also discussed.

Turbulence is a significant factor in near-road air quality, as it affects the initial dilution, dispersion, and the ultimate fate of pollutants. This study used computational fluid dynamics simulations to model the turbulent kinetic energy (TKE) on roadways, focusing on vehicle-induced turbulence. TKE was shown to decay with different power-law exponents depending on vehicle types; vehicle speeds and winds affect TKE; and thermal impacts are negligible. It was found that TKE is superimposed for vehicles in series; TKE does not dissipate far laterally, and the side-by-side interactions are not significant regardless of the directions. Thus, TKE for different traffic compositions may be expressed as a sum of the contribution from each type of vehicle. Insights gained in this study may enable the quantification of TKE for various traffic scenarios based on TKE values of single vehicle of different types, and simplify the TKE estimations in regional air quality models.

Salt iodization is widely available throughout the developing world. Incorporating other micronutrients into the existing salt iodization process could prevent multiple deficiencies. The thesis objective was to develop a stable formulation of salt dual fortified with folic acid and iodine, using a single solution that could be sprayed on. The micronutrients needed to be fully solubilized and stable in solution for at least one month. In the absence of an alkaline environment or antioxidant, iodine losses occur most likely due to the oxidation of folic acid by potassium iodate. Optimal salt formulations were prepared by spraying a pH 9 carbonate-bicarbonate buffer solution containing folic acid and iodine dissolved at 0.35% (w/v) each. Acceptable micronutrient retentions of > 90% were observed in refined salt after 6 months of storage at 45°C/60% relative humidity. Further investigations into increasing the concentration of iodine and folic acid in the spray solution are recommended.

Biogas, produced from anaerobic digestion of cattle manure, is an attractive alternative energy source as it is rich in methane. However, it is necessary to remove hydrogen sulfide from the biogas before it can be used in engines for electricity generation. Currently, large scale biogas systems employ physical adsorbing solvents to upgrade and purify biogas which is not economically feasible for small scale biogas systems. Activated carbon made from anaerobic digestate proves to be an effective adsorbent of hydrogen sulfide because it has minimal operating costs and essentially zero raw material cost. A model is developed to predict the adsorption capacity, carbon bed life span, and breakthrough time for this carbon material. By analyzing the reaction constant, adsorption constant, and degradation constant, adsorption behavior under different operating conditions were studied. The model can be scaled-up to model adsorption for biogas loading rates for small to large scale cattle farms.