Two types of protein isolates were prepared from de-hulled yellow mustard flour by aqueous extraction, membrane processing and acid precipitation of proteins at the isoelectric point (IEP 5.5). Their electrophoretic, main functional properties and protein composition were determined. The precipitated and acid soluble protein isolates had 83.0 and 96.0% protein content on a moisture and oil free basis, respectively. The acid soluble protein isolate had comparable functional properties to those of commercially available soybean and other protein isolates. The precipitated protein isolate exhibited less desirable functionality than the soluble isolate, due to its high lipid content (~25%); however, it was still comparable to soybean isolates. Storage temperature had limited effect on lipid oxidation, and hence the stability of the precipitated protein isolate at 25-45ºC. Taste and texture of wieners and bologna prepared with 1-2% of this isolate as binder were comparable to those prepared with soy protein isolates.

This thesis explores a rigorous approach to model the behaviour of an electrochemical cell. A simple planar electrochemical cell consisting of stainless steel electrodes separated by a sulfuric acid electrolyte layer is modeled from first principles. The model is a dynamic model and is valid under constant temperature conditions. The dynamic model is based on the Poisson-Nernst-Planck electrodiffusion theory and physical attributes such as the impact of nonlinear polarization, the stoichiometric reactions of the electrolyte and changes to the transport coefficients are investigated in stages. The system of partial differential equations has been solved using a finite element software package. The simulation results are compared with experimental results and discrepancies are discussed. The results suggest that the existing theory is not adequate in explaining the physics in the immediate vicinity of the electrode/electrolyte interface even though the general experimental and simulation results are in qualitative agreement with each other.

Doctor of Philosophy / Department of Biological & Agricultural Engineering / Donghai Wang, Scott Bean / The performance of soybean hulls and forage sorghum as feed stocks for ethanol production was studied. The main goal of this research was to increase fermentable sugars' yield through high-efficiency pretreatment technology. Soybean hulls are a potential feedstock for production of bio-ethanol due to their high carbohydrate content ([approximately equals]50%) of nearly 37% cellulose. Soybean hulls could be the ideal feedstock for fuel ethanol production, because they are abundant and require no special harvesting and additional transportation costs as they are already in the plant. Dilute acid and modified steam-explosion were used as pretreatment technologies to increase fermentable sugars yields. Effects of reaction time, temperature, acid concentration and type of acid on hydrolysis of hemicellulose in soybean hulls and total sugar yields were studied. Optimum pretreatment parameters and enzymatic hydrolysis conditions for converting soybean hulls into fermentable sugars were identified. The combination of acid (H[subscript]2SO[subscript]4, 2% w/v) and steam (140 °C, 30 min) efficiently solubilized the hemicellulose, giving a pentose yield of 96%. Sorghum is a tropical grass grown primarily in semiarid and dry parts of the world, especially in areas too dry for corn. The production of sorghum results in about 30 million tons of byproducts mainly composed of cellulose, hemicellulose, and lignin. Forage sorghum such as brown midrib (BMR) sorghum for ethanol production has generated much interest since this trait is characterized genetically by lower lignin concentrations in the plant compared with conventional types. Three varieties of forage sorghum and one variety of regular sorghum were characterized and evaluated as feedstock for fermentable sugar production. Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and X-Ray diffraction were used to determine changes in structure and chemical composition of forage sorghum before and after pretreatment and enzymatic hydrolysis process. Up to 72% of hexose yield and 94% of pentose yield were obtained using "modified" steam explosion with 2% sulfuric acid at 140°C for 30 min and enzymatic hydrolysis with cellulase (15 FPU/g cellulose) and [Beta]-glucosidase (50 CBU/g cellulose).

Doctor of Philosophy / Department of Chemical Engineering / Jennifer L. Anthony / Zeolites and zeolite-like materials have well-ordered structures and pores creating varying capacities for molecules based upon size, functional groups, polarity, and intermolecular forces making the materials useful for molecular sensing as well for molecules that are considered hazardous at very low concentrations with reproducible results because of these properties. This study will identify and characterize applications for zeolite and zeolite-like materials in gas and liquid phases based upon the dominating physical and chemical properties of the materials. The properties of interest include liquid phase ion exchange capacities, selectivities, gas/vapor phase adsorption capacity, and initial adsorption uptake rate. Zincosilicates have similar framework structures to aluminosilicate zeolites; however, they have distinct advantages over traditional zeolites. Zincosilicates typically have a higher ion density, lack “cages” in their structure which leads to all the cations being accessible for ion exchange, and have the ability to form three-membered rings which lead to large void spaces in their structure. These features lead to high capture capacities for divalent heavy metal mercury ions. In this work, the potential to use zincosilicates as ion exchangers such as VPI-7, VPI-9 and VPI-10 is presented. Results have shown that zincosilicates have capture capacities greater than traditional zeolites, even greater than those that have been synthesized with functional groups intended to increase metal sorption capacities. The selectivity coefficients in a binary ion exchange system were successfully modeled using the Gibbs-Donnan selectivity model. The selectivities for the zincosilicates were Pb>Na>Hg>K>Ca. Zeolites are also able to adsorb chemical species and therefore can be used as the recognition element in sensing devices. The sorption capacity of 2-chloroethyl ethyl sulfide, dimethyl methanephosphonate, ethanol, and n-butanethiol were examined with zeolites 13X, 4A, MCM-41, VPI-7, VPI-9, and ZSM-5. The zeolites selected provided very different framework composition, countercation, and surface area features for determining the most significant properties in adsorption. Zeolite 13X had the highest equilibrium and initial uptake rate for most compounds tested, whereas the low surface area zincosilicates, VPI-7 and VPI-9, had the lowest capacity. Based on these results, a piezoelectric device with an array of zeolites can be successfully employed as a sensor.

Doctor of Philosophy / Department of Chemical Engineering / James H. Edgar / The sublimation recondensation crystal growth of aluminum nitride, titanium nitride, and yttrium nitride were explored experimentally and theoretically. Single crystals of these nitrides are potentially suitable as substrates for AlGaInN epitaxial layers, which are employed in ultraviolet optoelectronics including UV light-emitting diodes and laser diodes, and high power high frequency electronic device applications. A thermodynamic analysis was applied to the sublimation crystal growth of aluminum nitride to predict impurities transport (oxygen, carbon, and hydrogen) and to study the aspects of impurities incorporation for different growth conditions. A source purification procedure was established to minimize the impurity concentration and avoid degradation of the crystal’s properties. More than 98% of the oxygen, 99.9% of hydrogen and 90% of carbon originally in the source was removed. The AlN crystal growth process was explored in two ways: self-seeded growth with spontaneous nucleation directly on the crucible lid or foil, and seeded growth on SiC and AlN. The oxygen concentration was 2 ~ 4 x 1018cm-3, as measured by secondary ion mass spectroscopy in the crystals produced by self-seeded growth. Crystals grown from AlN seeds have visible grain size expansion. The initial AlN growth on SiC at a low temperature range (1400°C ~1600°C) was examined to understand the factors controlling nucleation. Crystals were obtained from c-plane on-axis and off-axis, Si-face and C-face, as well as m-plane SiC seeds. In all cases, crystal growth was fastest perpendicular to the c-axis. The growth rate dependence on temperature and pressure was determined for TiN and YN crystals, and their activation energies were 775.8±29.8kJ/mol and 467.1±21.7kJ/mol respectively. The orientation relationship of TiN (001) || W (001) with TiN [100] || W [110], a 45o angle between TiN [100] and W [100], was seen for TiN crystals deposited on both (001) textured tungsten and randomly orientated tungsten. Xray diffraction confirmed that the YN crystals were rock-salt structure, with a lattice constant of 4.88Å. Cubic yttria was detected in YN sample from the oxidation upon its exposed to air for limited time by XRD, while non-cubic yttria was detected in YN sample for exposures more than one hour by Raman spectra.

Master of Science / Department of Mechanical and Nuclear Engineering / Kirby S. Chapman / The increased emissions monitoring requirements of industrial gas turbines have created a demand for less expensive emissions monitoring systems. Typically, emissions monitoring is performed with a Continuous Emissions Monitoring System (CEMS), which monitors emissions by direct sampling of the exhaust gas. An alternative to a CEMS is a system which predicts emissions using easily measured operating parameters. This system is referred to as a Parametric Emissions Monitoring System (PEMS). A review of the literature indicates there is no globally applicable PEMS. Because of this, a PEMS that is applicable to a variety of gas turbine manufacturers and models is desired. The research presented herein includes a literature review of NOx reduction techniques, NOx production mechanisms, current PEMS research, and combustor modeling. Based on this preliminary research, a combustor model based on first-engineering principles was developed to describe the NOx formation process and relate NOx emissions to combustion turbine operating parameters. A review of available literature indicates that lean-premixed combustion is the most widely-used NOx reduction design strategy, so the model is based on this type of combustion system. A review of the NOx formation processes revealed four well-recognized NOx formation mechanisms: the Zeldovich, prompt, nitrous oxide, and fuel-bound nitrogen mechanisms. In lean-premixed combustion, the Zeldovich and nitrous oxide mechanisms dominate the NOx formation. This research focuses on combustion modeling including the Zeldovich mechanism for NOx formation. The combustor model is based on the Siemens SGT-200 combustion turbine and consists of a series of well-stirred reactors. Results show that the calculated NOx is on the same order of magnitude, but less than the NOx measured in field tests. These results are expected because the NOx calculation was based only on the Zeldovich mechanism, and the literature shows that significant NOx is formed through the nitrous oxide mechanism. The model also shows appropriate trends of NOx with respect to various operating parameters including equivalence ratio, ambient temperature, humidity, and atmospheric pressure. Model refinements are suggested with the ultimate goal being integration of the model into a PEMS.

Master of Science / Department of Chemical Engineering / Larry E. Erickson / The damage that can be inflicted by ultraviolet radiation has gained widespread interest. Traditionally sunscreens are made of organic and inorganic components that block two of the three types of ultraviolet radiation, UVA and UVB. This report is a literature review of several articles that have investigated the effects of inorganic UV filters; specifically titanium dioxide and cerium dioxide. There are concerns about absorption of titanium dioxide into the skin and the adverse reactions that could occur, but it was found that there is little to no absorption. Similarly the photostability of titanium dioxide is a concern; this was found to be remedied in part by a surface treatment to the titanium dioxide. The combination of titanium dioxide and carnauba wax was also studied and found to enhance the properties of both the organic and inorganic filters. Ceria was studied as a possible replacement for titanium dioxide. It was found to have similar ultraviolet shielding properties while minimizing the photocatalytic activity and photocytotoxicity seen in titanium dioxide.

Doctor of Philosophy / Department of Chemical Engineering / Keith L. Hohn / Superparamagnetic iron oxide nanoparticle functionalization is an area of intensely active research, with applications across disciplines such as biomedical science and heterogeneous catalysis. This work demonstrates the functionalization of iron oxide nanoparticles with a quasi-monolayer of 11-sulfoundecanoic acid, 10-phosphono-1-decanesulfonic acid, and 11-aminoundecanoic acid. The carboxylic and phosphonic moieties form bonds to the iron oxide particle core, while the sulfonic acid groups face outward where they are available for catalysis. The particles were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), potentiometric titration, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectrometry (XPS), and dynamic light scattering (DLS). The sulfonic acid functionalized particles were used to catalyze the hydrolysis of sucrose at 80˚C and starch at 130˚C, showing a higher activity per acid site than the traditional solid acid catalyst Amberlyst-15, and comparing well against results reported in the literature for sulfonic acid functionalized mesoporous silicas. In sucrose catalysis reactions, the phosphonic-sulfonic nanoparticles (PSNPs) were seen to be incompletely recovered by an external magnetic field, while the carboxylic-sulfonic nanoparticles (CSNPs) showed a trend of increasing activity over the first four recycle runs. Between the two sulfonic ligands, the phosphonates produced a more tightly packed monolayer, which corresponded to a higher sulfonic acid loading, lower agglomeration, lower recoverability through application of an external magnetic field, and higher activity per acid site for the hydrolysis of starch. Functionalizations with 11-aminoundecanoic acid resulted in some amine groups binding to the surfaces of iron oxide nanoparticles. This amine binding is commonly ignored in iron oxide nanoparticle syntheses and functionalizations for biomedical and catalytic applications, affecting understandings of surface charge and other material properties.

Master of Science / Department of Chemical Engineering / Mary Rezac / Polymeric membranes have been playing important roles in gas or liquid separations. Polyimide polymers are of interest due to their commercially availability along with good transport, thermal and mechanical properties. In this study, two common commercial polyimide polymers, Matrimid and P84 were blended, to combine the good transport property of Matrimid with the plasticization resistance of P84. Matrimid/P84 blend solutions ranging from 0-100 wt. % Matrimid were prepared to make blend films. Physical properties (density, d-spacing, thickness), transport properties (permeability of H2, N2, CH4, Ar, He, CO2, and gas pairs selectivity), thermal property (mass loss curves of TGA), and liquid solutes (water, methanol, toluene, butanol, 1-propanol, 2-propanol) desorption behavior were measured or characterized. Rules of changing behavior of the properties with mass fraction of Matrimid were investigated, summarized, and interpreted mathematically. As Matrimid mass fraction increases, there are more mobility and space between polymer chains, therefore there are smaller density, larger d-spacing, larger fractional free volume (FFV) and larger permeability. The selectivity-permeability relationship follows the trade-off line. Thermal mass loss curve of the blend films in air have presented intermediate characteristic with rising fraction of Matrimid compared to individual polymers. A partial-miscible behavior has been found from the correlation between permeability and FFV. The desorption behavior was found to be reasonably described by the case III model, where the diffusion rate is similar with relaxation rate of polymers.

Doctor of Philosophy / Department of Chemical Engineering / Mary E. Rezac / Polyimide membranes have been used extensively in gas separation applications because of their attractive gas transport properties and the ease of processing these materials. Other applications of membranes, such as membrane reactors, which could compete with more traditional packed and slurry bed reactors across a wider range of environments, could benefit from improvements in the thermal and chemical stability of polymeric membranes. This work focuses on blending polyimide and polybenzimidazole polymers to improve the thermal and chemical stability of polyimide membranes while retaining the desirable characteristics of the polyimide. Blended dense films and asymmetric membranes were fabricated and characterized. Dense film properties are useful for studying intrinsic properties of the polymer blends. Transport properties of dense films were characterized from room temperature to 200°C. Properties including miscibility, density, chain packing and thermal stability were investigated. A process for fabricating flat sheet blended integrally skinned asymmetric membranes by phase inversion was developed. The transport properties of membranes were characterized from room temperature to 300°C. A critical characteristic of gas separation membranes is selectivity. Post-treatments including thermal annealing and vapor and liquid surface treatments were investigated to improve the selectivity of blended membranes. Vapor and liquid surface treatments with common, benign solvents including an alkane, an aldehyde and an alcohol resulted in improvements in selectivity.