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The vapor phase oxidation of 1.3-pentadiene, over heterogeneous catalysts, was investigated with the objective of producing 2,4-pentadienal and 2,4-pentadienoic acid. Copper and cobalt-molybdenum catalysts, both supported and unsupported, were utilized at various reaction temperatures, residence times and feed ratios. The matter of 1,3-pentadiene vaporization and introduction into the reactor system proved to be critical. Low temperature vaporization of the hydrocarbon and dilution with the oxidant, air, was found to be necessary to avoid polymerization of the feed. Alumina-supported catalysts were found to be very active, leading to severe cracking of the hydrocarbon feed and subsequent carbonization of the catalysts. Silica-supported catalysts did not suffer from this problem. At all conditional studied the oxidations were non-selective, with numerous products being observed. The desired product, 2,4-pentadienoic acid, was observed only in trace amounts over cobalt molybdate. 2,4-Pentadienal was observed over all catalysts. The highest yield of 2,4-pentadienal, 11%, occurred over cobalt molybdate.

In this thesis, the results of oxidation and decarburization experiments with pure iron-carbon alloys over the temperature range 800 - 950ºc, and in atmospheres of varying carbon monoxide - carbon dioxide ratio are reported. Most of the experimental work is concerned with a 1.065 weight percent carbon alloy at temperatures where austenite is the stable phase. Complex kinetic behaviour was observed for this alloy in the range 10 - 100 volume percent carbon dioxide. An analysis is given which in turn associates the kinetics with a pure diffusion controlled decarburization model and a pure surface controlled decarburization model. The latter best represents the interaction of the decarburization mechanism with the scaling process on Y - iron. Metallographic evidence is provided where possible in support of the results of the afore-mentioned analysis. Mathematical relations are introduced which attempt to describe qualitatively the kinetics of the carbon alloys in all the atmospheres employed. A statement is made as to the applicability of the model to carbon steels in general at temperatures where austenite is the stable phase and where the atmospheres employed are of various carbon monoxide - carbon dioxide ratio. / Thesis / Master of Science (MS)

Energy regulations have shifted commercial retail cases from fluorescent to light emitting-diode lights (LED), however the effect of LED light on milk quality (flavor and nutritional content) has not been thoroughly studied. Packaging efficacy of light protecting additives (LPA) in high-density polyethylene (HDPE) was studied for protection against light-induced oxidation of high-temperature short-time (HTST) 2% milk under fluorescent (1882±993 lux) and LED light (915±150 lux). Milk quality measures included oxidation level, riboflavin (Rb) retention, headspace volatiles, and sensory evaluation were analyzed to determine the interaction between light source, packaging material, and storage time. HDPE packaging included translucent package (0% TiO2) serving as control (light-exposed, light-protected: foil and plastic overwrap) and three LPA packages (low (1.3% TiO2), high (4.9% TiO2), yellow). Rb concentration decreased among all packages (40%-60%) after 72h for both lights. Volatile aldehydes (TBARS), increased in all packages (23%-82%) during storage over 72h at 4C. Sensory evaluation (triangle test) revealed detectable flavor changes at a TBARS value of 0.11 mg/L; LPA packages saw this change starting at 4h and continued through 72h. The high package protected milk flavor effectively at 4h under fluorescent light; yellow package was effective for 4h under LED light. Despite detectable sensory differences, acceptability scores (9-point hedonic scale) were significantly greater for milk exposed to LED light in light-protected and high packages (p<0.05). We conclude that LED light may be less harmful to milk flavor vitamin content, but packaging needs to be improved to maintain milk's ideal flavor past 4h of light exposure. / Master of Science in Life Sciences

The objective of this study is to use a mixed flow reactor system to determine the dissolution rate and infer potential mechanisms of arsenopyrite (FeAsS) oxidation by dissolved oxygen at 25°C and circumneutral pH. Release rates for iron, arsenic and sulfur are calculated for a variety of initial dissolved oxygen (DO) concentrations. Results indicate that the rate of arsenopyrite oxidation, represented by the rate law r = A(6.76 x 10-11) where the rate, r, is in mol/s and surface area, A, is in m2, is not significantly dependent on DO concentration. Arsenic and sulfur are released in a 1:1 molar ratio while iron is released more slowly due to precipitation of iron oxyhydroxides. Our results suggest that the rate determining step in arsenopyrite oxidation is determined by the attachment of oxygen at the anodic site in the mineral, and not the transfer of electrons from the cathodic site to oxygen, as is suggested for other sulfide minerals such as pyrite. Previous work on FeAsS oxidation has been limited to low pH conditions with ferric iron as the oxidant. However, not all arsenopyrite weathering occurs exclusively in acidic environments. For example, at an abandoned arsenopyrite mine in Virginia, the pH of ground and surface waters is consistently between 4 and 7. Results of this study provide important insight to arsenic mobilization processes and rates, at field-relevant conditions, consequently aiding in the effort to understand arsenic release and retention in the environment. / Master of Science

Soluble manganese (Mn) is a common contaminant in drinking water sources. High levels of Mn can lead to aesthetic water quality problems, necessitating removal of Mn during treatment to minimize consumer complaints. Mn may be removed during granular media filtration by the "natural greensand effect," in which soluble Mn adsorbs to manganese oxide-coated (MnOx(s)) media and is then oxidized by chlorine, forming more manganese oxide. This research builds on a previous model developed by Merkle et al. (1997) by either neglecting the empirically determined available fraction of sorption sites (referred to as the "simple" model), which took into account the fact that some adsorption sites in the porous media were inaccessible, or by explicitly accounting for the transport and reaction processes within the porous structure of the MnOx(s) coating (referred to as the "mechanistic" model). Both models were applied to experimental data and used to evaluate the oxidation rate constant, which was the only unknown parameter. An inverse relationship between the fitted reaction rate constant and chlorine concentration was observed, showing that the oxidation reaction does not depend on chlorine concentration for the experimental conditions considered. In a sensitivity analysis, the adsorption isotherm and reaction rate were found to have the greatest impact on predicted Mn removal. The simple model should prove useful for designing contactor units for manganese removal, provided its limitations are clearly understood, while the mechanistic model should be able to resolve differences in the various types of oxide coating (internal porosity, surface area and coating thickness) and will allow a more fundamental and mechanistically-consistent evaluation of the appropriate form of the oxidation rate expression. However, further research is needed to more completely characterize the adsorption and reaction mechanisms over the range of conditions commonly encountered in water treatment plants. / Master of Science