Thesis (M.S.)--University of Wyoming, 2009. / Title from PDF title page (viewed on June 18, 2010). Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 89-95). Also available on the World Wide Web.

Thesis (M.S.)--University of North Carolina Wilmington, 2007. / Includes bibliographical references (leaves: 41-42)

Thesis (M.Sc.)--York University, 2005. Graduate Programme in Geography. / Typescript. Includes bibliographical references (leaves 133-138). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11778

Advanced oxidation processes are capable of removing organic compounds that cannot be removed by conventional water treatment methods. Among the oxidation processes, photo-catalysis using titanium dioxide (TiO2) is a promising method but suffers from rapid electron-hole recombination rates and only absorbs UV light which is a small percentage (5 percent) of the total solar radiation. Therefore there is a need to reduce the recombination rates and also extend the absorption of the photo-catalyst into the visible region which constitutes 55 percent of the total solar radiation. The major aims of this study were to prepare plasmon metal decorated and doped TiO2 photo-catalysts immobilized on quartz substrates and test their photo-catalytic and antimicrobial activities. The effect of film thickness (loading) and use of different shapes of plasmon metal nanostructures was investigated. TiO2 thin films were prepared by a sputter coating technique while plasmon metal (Au & Ag)/carbon co-doped TiO2 by a simple sol gel process and plasmon metal films were prepared by the thermal evaporation technique. Different plasmon metal nanostructures (nanorods, dendrites, nanowires and spherical nanoparticles) were prepared using a wet chemical technique using sodium borohydride as the reducing agent. Nanocomposites of co-doped TiO2 photo-catalyst and plasmon elements of different proportions were also prepared. The prepared photo-catalysts were coated onto etched and MPTMS (3-Mercaptopropyl trimethoxysliane) treated quartz glass substrate which is a stable support favouring easy recovery. The prepared materials were characterized by XRD, HRTEM, TEM, HRSEM, FT-IR, SEM, PIXE and TGA while the doped TiO2 was characterized by XPS, BET, CHNS and Raman Spectroscopy. The effect of pH of solution, presence of other contaminants and salts in solution, initial concentration of the model pollutant and type of the plasmonic elements on the photocatalytic activity of TiO2 towards 4-(4-sulfophenylazo)-N,N-dimethyl aniline (methyl orange) were also investigated. The selected TiO2 photo-catalyst films were tested for antimicrobial properties. The effect of different types of plasmon elements on the antimicrobial activity of TiO2 against E. coli ATCC 3695 was evaluated under both sunlight and weak UV light. Under UV light, Ag showed the highest enhancement in photo-catalytic activity of TiO2 than Au and Cu. The photo-catalytic activity of TiO2 increased with an increase in Ag content to an optimum loading and then started to decrease with a further increase in loading. For Cu and Au, photo-activity activity increased with an increase in plasmon metal content. Under sunlight, Cu showed the highest enhancement of TiO2 photocatalytic compared to Ag and Au. The change in order of deposition showed that Au films enhanced the photo-activity better when they were deposited underneath rather than on top of TiO2 on quartz supports but Ag films performed better in enhancing photo-activity when they were deposited on top of TiO2. The use of bimetallic layers and three layer systems of different plasmon elements enhanced photo-catalytic activity better than the use of a monometallic layer. The presence of other organic contaminants and salts in solutions was found to reduce the photo-degradation of methyl orange due to preferential adsorption of other contaminants. When the pH was increased, the photocatalytic activity of TiO2 towards methyl orange was reduced. In antimicrobial studies, it was found that the plasmon elements greatly improved the antibacterial action of TiO2 against Escherichia coli ATCC 3695 in water and the best antibacterial action was observed with silver/carbon co-doped TiO2 photo-catalyst under sunlight The doped samples consisted of polydisperse nanoparticles which were found to be beneficial for photo-catalytic activity enhancement under sunlight.

Magister Scientiae - MSc / It is widely believed that hydrogen will within a few tens of years become the means of storing and transporting energy. The reason is the depletion of hydrocarbons and the relatively facile production of hydrogen from various renewable sources of energy. Hydrogen can be combusted in an efficient way in a fuel cell with water as emission product. As concerns over air pollution and global warming increase, the incentive to switch to clean and efficient hydrogen economy becomes greater and the transition may occur well before hydrocarbon reserves are extinct. The overall goal of the project is to develop the knowledge base for solid-state hydrogen storage technology suitable for stationary and mobile applications. In order to accomplish this goal, the project will have a dual focus which includes the synthesis of novel nano-structured hydrogen storage materials and systems that can accurately analyze the materials. The aim of this research is to develop a novel composite hydrogen storage material with high wt% storage capacity, high intrinsic safety, appropriate thermodynamics, high mechanical strength, reversibility of the system and fast kinetics based on a well known “low temperature” intermetallic alloy (Ti/Fe) as the core. In the course of achieving this objective, the structural, thermal, chemisorptive and physisorptive attributes of this material on a nanoscale have been evaluated considering that nano-structuring is a potentially promising approach for controlling bond strength, kinetics, and sorption temperatures and pressures. By combining different materials with suitable catalytic and thermodynamic properties, a new class of hybrid hydrogen storage material has been developed. More importantly, the focus was to increase the capacity of hydrogen sorption in this material. This goal was achieved with the mechano-chemical pre-treatment of Ti/Fe alloy and surface modification with carbon nanotubes, binary palladium and magnesium metals via a layer-by-layer modification technique. The chemical and mechanical stability of hydrogen storage materials is of great importance because hydrogen storage materials must withstand repeated adsorption and desorption cycles. The layer by layer approach that was used in this project allowed the investigation of the chemical and mechanical stability of the materials as each layer was added. Through this layer by layer approach suitable nano-particles were introduced that are chemically and mechanically stable. The knowledge emanating from this investigation is expected to allow the directed design of new, higher-efficiency, recyclable hydride-based materials in pursuance of the 6.0 wt% goal set forth by the US Department of Energy. / South Africa

After the end of hydric recultivation from the monitored source of watering, artificially bulit-up lakes are fed with the water from their own basin. This water is not so systematically monitored as compared to the water from the new lake and the sources of its filling. This thesis summarizes findings about the developement of artificially made basin in the mining area and explains differences between various basins. Further, this work deals with the characteristics of water feeding lake "Chabarovicke jezero (Milada)", which was bulit-up during hydric recultivation of the mineshaft in the soft-coal quarry Chabarovice. Monitored basins have different area, slope, vegetation coverage and distribution of dissolved compounds. These factors have significant impact on the character of the water in affluents. We found out, that affluents from the own basin have high concentration of dissolved compounds resulting in the unwanted enrichment of the lake. Big problem was the high concentration of sulphates and nitrates, which in all affluents, except for one, exceed tolerated limits for surface waters. In the course of time, concentrations of dissolved compounds go down. Particular affluents differ between each other and the main impact on the water characteristic is the slope, exposition and area. In the...

The effect of copper on Legionella pneumophila in potable water plumbing systems is dependent on its dose and water chemistry. For instance, prior research demonstrated that the presence of aluminum hydroxide from anode rods in water heaters can bind copper and render high doses non-toxic. On this basis it was also hypothesized that iron hydroxide would have similar effects and that lower levels of copper may act as a nutrient encouraging Legionella growth. Here we conducted complementary experiments at bench, microcosm and pilot-scale to evaluate the effect of copper speciation and dose on L. pneumophila. At bench-scale, the addition of 5 mg/L as Fe iron hydroxide to a solution with 1 mg/L copper decreased soluble copper from > 90% down to < 20% at pH 6.5-7. The reduction in soluble copper caused ~3-logs higher L. pneumophila culturability when iron was added with copper when compared to a condition with copper alone. In a 9-month microcosm test using simulated glass water heaters with PEX pipe, a complete range of copper doses (0, 4, 30, 250 and 2000 g/L) were tested in triplicate. Over the first phase of research covered herein, the L. pneumophila levels were low at the four lowest doses of copper, and non-detectable at the highest dose. Moreover, total cell counts were highest at 250 g/L copper, lowest at 2000 g/L copper, and in between these extremes at the lower copper doses. This ongoing experiment will continue for months after this thesis was complete. Pilot-scale experiments were conducted with anode rods removed from tank water heaters, to examine the effects of unprotected corrosion of the steel on iron release and Legionella pneumophila levels in systems with 1) added copper (WH-Cu), 2) copper and phosphate corrosion inhibitor (WH-Cu+PO4-3), 3) phosphate corrosion inhibitor alone (WH-PO4-3) and 4) a control with neither copper nor inhibitor (WH-Control). While there were slight differences in iron between the conditions, the iron concentration in the water of the tanks did not dramatically increase compared to when the powered anodes were still installed and reducing corrosion. Because the iron level was usually < 0.1 mg/L, the released iron dose was not high enough to reduce soluble copper. In fact, oddly, soluble copper increased by 37-183%, mostly likely because the installed anode rods were suppressing copper release. Consequently, with the anode rods removed, the dose of 2000 g/L copper still had a strong antimicrobial effect. The levels of L. pneumophila increased in the order WH-Cu (2.6-logs CFU/L) < WH-PO4-3 (5.1-logs CFU/L) ≈ WH-Control (5.1-logs CFU/L). The addition of phosphate precipitated some of the added copper, such that the condition with copper and phosphate [WH-Cu+PO4-3 (4.2-logs CFU/L)] had L. pneumophila in between the condition with copper alone and that with no added copper. When the copper dose in the pilot rig was reduced to 1000 g/L, Legionella increased somewhat in the system with added copper compared to the control, and L. pneumophila increased in the water heaters in the order WH-Cu (3.4-logs CFU/L) < WH-Cu+PO4-3 (4.3-logs CFU/L) < WH-PO4-3 (4.9-logs CFU/L) ≈ WH-Control (5.0-logs CFU/L). Overall, an antimicrobial effect of copper was maintained in the water heaters even after the anodes were removed and iron in the water increased slightly. If iron corrosion and release to water were much higher without the anode rods than observed in this study, it would be predicted that the higher iron would have reduced the copper antimicrobial effect. / Master of Science / The effect of copper on Legionella pneumophila in potable water plumbing systems depends on its dose and water chemistry. For instance, prior research demonstrated that the presence of aluminum hydroxide from anode rods in water heaters can bind copper and render high doses non-toxic. It was also hypothesized that iron hydroxide would have similar effects and that lower levels of copper may act as a nutrient encouraging Legionella growth. Here we conducted complementary experiments at bench, microcosm and pilot-scale to evaluate the effect of copper's chemistry and dose on L. pneumophila. At bench-scale, the addition of a high level of iron to a solution with copper decreased the amount of copper available to Legionella from > 90% down to < 20% at pH 6.5-7. The reduction in bioavailable copper caused ~3-logs higher L. pneumophila when iron was added with copper when compared to a condition with copper alone. In a 9-month microcosm test using simulated glass water heaters with PEX pipe, a complete range of copper doses (0, 4, 30, 250 and 2000 g/L) were tested. The L. pneumophila levels were low and there were no significant differences between the five doses in the beginning phases of the experiment reported herein. However, total cell counts were highest at 250 g/L copper, lowest at 2000 g/L copper, and in between these extremes at the lower copper doses. This suggests that 250 g/L may be optimal in encouraging overall microbial growth. Pilot-scale experiments were conducted with anode rods removed from water heaters to examine the effects of unprotected corrosion of the steel tank on iron release and Legionella pneumophila levels. The four water heaters had added copper (WH-Cu), copper and phosphate corrosion inhibitor (WH-Cu+PO4-3), phosphate corrosion inhibitor alone (WH-PO4-3) and neither copper nor inhibitor (WH-Control). The iron concentration in the water of the tanks did not dramatically increase compared to when the powered anodes were used to reduce corrosion. Nevertheless, there were still slight differences in iron concentration between the replicate water heaters. When 2000 g/L copper was dosed, WH-Cu and WH-Control had statistically higher iron levels than WH-PO4-3, consistent with copper increasing corrosion of the unprotected tank. However, because the iron level was usually < 0.1 mg/L, the released iron dose was not high enough to reduce bioavailable copper. In fact, bioavailable copper went up when the anode rod was removed, most likely because the anode rods were protecting brass plumbing from corrosion. With the anode rods removed a dose of 2000 g/L copper had a strong antimicrobial effect. The levels of L. pneumophila increased in the order WH-Cu < WH-PO4-3 ≈ WH-Control. The addition of phosphate reduced some of the bioavailable copper, such that the condition with copper and phosphate (WH-Cu+PO4-3) had L. pneumophila in between the condition with copper alone and that with no added copper. When the copper dose in the water heaters was reduced to 1000 g/L, Legionella increased somewhat in the system with added copper compared to the control, and L. pneumophila increased in the order WH-Cu < WH-Cu+PO4-3 < WH-PO4-3 ≈ WH-Control. Overall, an antimicrobial effect of copper was maintained in water heaters even after the anodes were removed and even though iron in the water increased slightly. If iron corrosion and release to water was much higher than occurred in this study, it would be expected that the iron could have reduced the copper antimicrobial effect.

No description available.

In the first experiment, effects of brewing time, chlorine, chloramine, iron, copper, pH and water hardness were investigated for their effects on extraction of epigallocatechine gallate (EGCG) and caffeine in green tea and oolong tea aqueous infusions. The extraction of EGCG and caffeine were lower when green tea was brewed in hard water compared to distilled water. Brewing green tea and Oolong tea in tap water resulted in higher extraction of caffeine but had no effect on EGCG compared to distilled water. The extraction of EGCG and caffeine were significantly increased (P<0.05) when green tea and Oolong tea were brewed in the chlorinated water at 4.0 mg free chlorine per liter. The purpose of the second experiment was to optimize SDE conditions (solvent and time) and to compare SDE with SPME for the isolation of flavor compounds in Jin Xuan oolong tea using Gas Chromatography- Mass Spectrometry (GC-MS) and Gas Chromatography- Olfactrometry (GC-O). The concentration of volatile compounds isolated with diethyl ether was higher (P<0.05) than for dichloromethane and concentration was higher at 40 min (P<0.05) than 20 or 60 minutes. For SDE, 128 volatiles were identified using GC-MS and 45 aroma active compounds using GC-O. The number of volatiles identified using GC-MS was lower in SPME than SDE. For SPME, 59 volatiles and 41 aroma active compounds were identified. The composition of the volatiles isolated by the two methods differed considerably but provided complementary information. The goal of the third experiment was to determine effects of panning on flavor volatile compositions of oolong using GC-MS and GC-O. Simultaneous Distillation and Extraction (SDE) and Solid Phase Microextraction (SPME) techniques were applied for extraction of volatiles in panned and unpanned teas. A total of 190 volatiles were identified from SDE and SPME extractions using GC-MS and GC-O. Trans-nerolidol, 2- hexenal, benzaldehyde, indole, gernaiol, and benzenacetaldehyde contents were significantly decreased (P<0.05) by panning; however, panning increased (P<0.05) contents of linalool oxide, cis jasmone, methyl salicylate in oolong tea. Overall, panning significantly changes the volatile compositions of the tea and created new aroma active compounds. / Ph. D.