Although many commercial chemicals can dissociate, the study of the biological and environmental fate of ionogenic organic chemicals (IOCs) is still in its infancy. Uptake of the veterinary drug diclofenac in vultures and cattle was successfully simulated with a newly developed physiologically-based pharmacokinetic model for IOCs, lending credence to diclofenac’s proposed role in South Asian vulture population declines. Proteins and phospholipids rather than total lipids control the tissue distribution of diclofenac. A method was developed to simultaneously extract neutral and acidic pesticides and benzotriazoles from water samples with recoveries ranging 70-100%. This method was applied to samples from a laboratory calibration experiment of the Polar Organic Chemical Integrative Sampler. The sampler had higher uptake for neutral and acidic pesticides when filled with triphasic sorbent admixture and OASIS MAS sorbent, respectively. While either sorbent can also be applied for methylated benzotriazoles, neither is capable of quantitatively sampling all three compound groups.

Master of Science / Department of Chemical Engineering / Keith Hohn / The study will utilize a probabilistic reaction modeling method for ring-opening reactions of epoxide. In particular, to elucidate the reaction mechanism by the methods presented, focus will be placed on the nucleophillic attack of ethylene oxide by ammonia and its anion. This focus was chosen because of the potential to gain significant advantage in computational intensity required to model the epoxy-amino macromolecular curing reactions and resulting thermochemical and physical properties of the cured resin. The method employed utilizes the combinatorial probability that 1. Two molecules will approach a transition state with sufficient energy to drive reaction 2. Any reaction will occur for a given penetration into the potential energy surface. The concept of a transition state is relaxed to allow a dynamic probability that any reaction will proceed given a position on the intrinsic reaction coordinate (IRC) rather than searching for a specific transition state of theoretical reaction probability. 3. The reaction that occurs yields a desired stable or semi-stable molecular complex This study will focus on identifying possible stable and semi-stable products and corresponding rate constants. The technique developed here is novel in that it provides an unsupervised method to identify all structures corresponding to minima on the potential energy surface. The technique provides a pragmatic and efficient approach to sample a molecular system for different reaction mechanisms and provides a relative energy requirement to achieve these mechanisms with no presupposition of the mechanism, product, or transition state. It is possible from this data to derive rate constants for a reacting system, however, the rate constant derived for the EO/NH2 molecular system yielded significantly understated reaction probabilities and therefore rate constants.

Doctor of Philosophy / Department of Chemical Engineering / Vikas Berry / Nanoscale materials invite immense interest from diverse scientific disciplines as these provide access to precisely understand the physical world at their most fundamental atomic level. In concert with this aim of enhancing our understanding of the fundamental behavior at nanoscale, this dissertation presents research on three nanomaterials: Gold nanoparticles (GNPs), Graphene and ultra-thin Boron Nitride sheets (UTBNSs). The three-fold goals which drive this research are: incorporating mobility in nanoparticle based single-electron junction constructs, developing effective strategies to functionalize graphene with nano-forms of metal, and exfoliating ultrathin sheets of Boron Nitride. Gold nanoparticle based electronic constructs can achieve a new degree of operational freedom if nanoscale mobility is incorporated in their design. We achieved such a nano-electromechanical construct by incorporating elastic polymer molecules between GNPs to form 2-dimensional (2-D) molecular junctions which show a nanoscale reversible motion on applying macro scale forces. This GNP-polymer assembly works like a molecular spring opening avenues to maneuver nano components and store energy at nano-scale. Graphene is the first isolated nanomaterial that displays single-atom thickness. It exhibits quantum confinement that enables it to possess a unique combination of fascinating electronic, optical, and mechanical properties. Modifying the surface of graphene is extremely significant to enable its incorporation into applications of interest. We demonstrated the ability of chemically modified graphene sheets to act as GNP stabilizing templates in solution, and utilized this to process GNP composites of graphene. We discovered that GNPs synthesized by chemical or microwave reduction stabilize on graphene-oxide sheets to form snow-flake morphologies and bare-surfaces respectively. These hybrid nano constructs were extensively studied to understand the effect and nature of GNPs’ interaction with graphene, and applied to address the challenge of dispersing bare-surfaced GNPs for efficient liquid-phase catalysis. We also revisited the functionalization of graphene and present a non-invasive surface introduction of interfaceable moieties. Isostructural to graphene, ultrathin BN sheet is another atomic-thick nanomaterial possessing a highly diverse set of properties inconceivable from graphene. Exfoliating UTBNSs has been challenging due to their exceptional intersheet-bonding and chemical-inertness. To develop applications of BN monolayers and evolve research, a facile lab-scale approach was desired that can produce processable dispersions of BN monolayers. We demonstrated a novel chlorosulfonic acid based treatment that resulted in protonation assisted layer-by-layer exfoliation of BN monolayers with highest reported yields till date. Further, the BN monolayers exhibited extensively protonated N centers, which are utilized for chemically interfacing GNPs, demonstrating their ability to act as excellent nano-templates. The scientific details obtained from the research shown here will significantly support current research activities and greatly impact their future applications. Our research findings have been published in ACS Nano, Small, Journal of Physical Chemistry Letters, MRS Proceedings and have gathered >45 citations.

Doctor of Philosophy / Department of Chemical Engineering / Jennifer L. Anthony / Zeolites and zeolite-like materials are a group of porous materials with many applications in industry including but not limited to detergent builders and catalyst in the oil refining and petrochemical industry, due to their unique properties such as uniform pore size, large surface area and ion-exchange capacity. Researchers are constantly seeking new methods to synthesize zeolites. Zeolites are commonly synthesized in water. Then in 2004, a new method called ionothermal synthesis was invented by Dr. Morris and his colleagues, using ionic liquids (ILs) and eutectic mixtures as the solvent. In contrast to water, ILs and eutectic mixtures have negligible vapor pressure, thus making the use of high-pressure vessel unnecessary. In addition, they have various structures which could render new structures to frameworks of zeolite. Furthermore, since the cations of some ILs have structures which are similar to common structure directing agents, they theoretically could be used both as solvent and structure directing agent in ionothermal synthesis, possibly simplifying the synthesis process. This project is aimed at investigating the behavior of precursors of zeolites in ionic liquids and the interaction between precursors and ionic liquids in ionothermal synthesis because these fundamental properties could be useful in the current and future synthesis of zeolites. First, solubilities of different precursors, including Syloid 63 silica particles, aluminium isopropoxide (Al(OiPr)3) and phosphoric acid (H3PO4) in ILs with different structures are reported. Parameters such as activity coefficient and Henry’s constant are calculated from the solubility result. Second, interaction between precursors and ILs are studied. It is found that the addition of ILs in Al(OiPr)3 could change the structure of Al(OiPr)3, especially with the presence of H3PO4. Both ILs’ structures and temperature are capable of influencing the structure change of Al(OiPr)3. Third, hydrochloric acid is used for the first time as the mineralizer to synthesize aluminophosphates in ILs and it could lead to both dense and porous materials. Regardless of the acid used, frameworks synthesized after several hours always undergo a dramatic change after further heating. A slightly longer alkyl chain of ILs could accelerate the formation of crystalline materials. Increasing concentration of precursors in the reaction gel could increase the yield, but the same framework is not retained. Researches have also been done on stability of ILs in the synthesis process and it is found that heat and the presence of H3PO4 could decompose ILs, but the decomposed amount is extremely small.

In this study, novel bio-inks formulated with horseradish peroxidase, HRP, and some additives were successfully developed for piezoelectric inkjet application. The optimized bio-ink formulation had a reliable jetting performance and maintained the biofunctionality before and after printing. The bio-ink also demonstrated a good storage life for up to 40 days at 4 oC with a negligible loss of biofunctionality. However, it was observed that some additives used in the bio-ink for obtaining necessary operational characteristics had detrimental effects on the enzyme activity. Especially, it was found that various viscosity modifiers typically used in commercial inkjet inks significantly impaired HRP activity prior to printing. Sodium Carboxymethyl Cellulose was shown to be an effective viscosity modifier that had no adverse effect on the biological activity of the HRP enzyme. Using a confocal scanning fluorescent microscope, a method for characterizing the spatial distribution of the active enzyme within the cellulosic paper substrates after inkjet printing was developed. Interestingly, it was found that the active printed HRP enzyme was mostly located in the cell walls of the cellulosic fibers instead of near the pigments or fillers. In an effort to better understand the fundamental interactions between the enzyme and the immobilization substrates, HRP adsorption isotherms on various substrate surfaces were obtained using the depletion method. The substrates included not only pulp fibers with varying degree of hydrophobicity and pigment and latex (the key materials used in papermaking), but also other types of cellulosic fibers of different morphologies, crystallinities, porosities, or surface charge densities. The influence on enzyme adsorption and inactivation behaviour of these substrates was compared with that of polystyrene beads (dialysed), which has been well studied in the literature. Results from this thesis indicated that hydrophobic interactions between the enzyme and the substrate surfaces had a major impact on the HRP adsorption behavior, while electrostatic interactions played a minor role. However, strong hydrophobic interactions could lead to enzyme inactivation. Research findings from this study suggested that cellulosic pulp fibers could be tailor-made into excellent enzyme immobilization supports by using existing fiber surface modification techniques.

This thesis describes a fundamental study of the miscibility and the nature of the interface between components of core-shell polymer blends using the technique of Fluorescence Resonance Energy Transfer (FRET) coupled with data analysis that involves Monte-Carlo simulations. Our aim in this study was to develop a fundamental methodology to quantitatively determine the width of the interface between the two components in binary polymer blends. At the current state of the art, data analysis of FRET experiments requires translational symmetry. In the system under study, uniform core-shell structures satisfy this criterion. Thus, in this work our focus was directed toward the study of a blend system with a core-shell structure. For this FRET study, I have identified a number of potential donor and acceptor dye pairs that fluoresce in the visible range of the spectrum and can be chemically attached to polymers. Among them, I selected, as the donor and the acceptor, a pair of naphthalimide dyes that have not previously been used for FRET experiments. Model experiments showed that while the fluorescence decay profile of the donor chromophore was exponential in solution, it was not exponential in polystyrene (PS) or poly(methyl methacrylate) (PMMA) films. Thus, I carried out refinements to existing FRET theory to interpret the data generated by using these dyes. Also, I derived a new model to predict the fluorescence intensity of non-exponential decaying donor dyes in core-shell systems. I selected a model system composed of a PS core surrounded by a PMMA shell. The PS core particles were prepared by miniemulsion polymerization to obtain cross-linked PS particles with a narrow size distribution. Seeded emulsion polymerization under starved-fed condition was employed to synthesize monodisperse dye-labeled core-shell particles. The extent of miscibility and the nature of interface between the core and the shell polymers were retrieved from a combined study by Monte-Carlo simulations and analysis of the donor fluorescence intensity decays. Agreement between the retrieved interface thickness and the literature data on PS-PMMA validates the methodology developed here for the use of such donor dyes in FRET studies on polymer blends.

Biofilm systems such as the moving bed biofilm reactor (MBBR) are finding increased application in wastewater treatment. One important process that governs MBBRs and yet is poorly understood is the rate of biofilm detachment. The detachment of cells from biofilm surfaces controls both the accumulation of biofilm and the quantity of biomass that is suspended in the bulk liquid phase. This changing balance of attached and suspended cells, in this thesis named the biosolids dynamics, can impact the efficacy of MBBRs. The goal of this research was to investigate how the biosolids dynamics are influenced by process changes relevant to applied wastewater treatment systems and suggest new routes to reactor design and optimization. To achieve this goal, the work addresses three separate but interconnected lines of inquiry. First, multivariate analysis (Principal Component Analysis, Partial Least Squares) was used to examine 2 years of historical data from an MBBR operating at a Canadian pulp mill in order to identify key process variables, perform process diagnostics, and act as a predictive tool. Secondly, the effect of calcium concentration on biofilm structure, microbiology and reactor performance was investigated in four laboratory-scale MBBRs operated at a range of calcium concentrations (1 to 300 mg/L Ca2+). It was found that above a threshold calcium concentration between 1-50 mg/L, MBBR biofilms were observed to be thicker with greater density, contain larger anoxic regions adjacent to the carrier substratum, have more proteinaceous EPS, and have altered microbial community structure. The results suggest an important role for calcium that should be considered in the design and operation of MBBRs. In the final line of inquiry, a diffusion-reaction biofilm model was adapted to represent the key processes of the MBBR. The model was found to simulate average trends observed in the lab-scale experiments allowing for quantification of the detachment rate. Transient periods of reactor starvation were also simulated by introducing a novel metabolic state function to account for down-regulation of metabolism as a result of starvation. This approach was found to accurately simulate starvation response when coupled with detachment expressions that were growth-dependant.

Defects in polyethylene film are often caused by contaminant particles in the polymer melt. In this research, particle properties obtainable from in-line melt monitoring, combined with processing information, are used to predict film defect properties. “Model” particles (solid and hollow glass microspheres, aluminum powder, ceramic microspheres, glass fibers, wood particles, and cross-linked polyethylene) were injected into low-density polyethylene extruder feed. Defects resulted when the polyethylene containing particles was extruded through a film die and stretched by a take-up roller as it cooled to form films 57 to 241mm in thickness. Two off-line analysis methods were further developed and applied to the defects: polarized light imaging and interferometric imaging. Polarized light showed residual stresses in the film caused by the particle as well as properties of the embedded particle. Interferometry enabled measures of the film distortion, notably defect volume. From the images, only three attributes were required for mathematical modeling: particle area, defect area, and defect volume. These attributes yielded two ”primary defect properties”: average defect height and magnification (of particle area). For all spherical particles, empirical correlations of these properties were obtained for each of the two major types of defects that emerged: high average height and low average height defects. Analysis of data for non-spherical particles was limited to showing how, in some cases, their data differed from the spherical particle correlations. To help explain empirical correlations of the primary defect properties with film thickness, a simple model was proposed and found to be supported by the high average height defect data: the “constant defect volume per unit particle area” model. It assumes that the product of average defect height and magnification is a constant for all film thicknesses. A numerical example illustrates how the methodology developed in this work can be used as a starting point for predicting film defect properties in industrial systems. A limitation is that each prediction yields two pairs of primary defect property values, one pair for each defect type. If it is necessary to identify the dominant type, then measurement of a length dimension of sufficient defects in the film is required.

The viscous oil-water hydrodynamics in a microchannel and phase equilibria of heavy oil and carbon dioxide gas have been investigated in connection with the enhanced recovery of heavy oil from petroleum reservoirs. The oil-water flow was studied in a circular microchannel made of fused silica with an I.D. of 250 µm. The viscosity of the silicone oil (863 mPa.sec) was close to that of the gas-saturated heavy oil in reservoirs. The channel was always initially filled with the oil. Two different sets of experiments were conducted: continuous oil-water flow and immiscible displacement of oil by water. For the case of continuous water and oil injection, different types of liquid-liquid flow patterns were identified and a flow pattern map was developed based on Reynolds, Capillary and Weber numbers. Also, a simple correlation for pressure drop of the two phase system was developed. In the immiscible displacement experiments, the water initially formed a core-annular flow pattern, i.e. a water core surrounded by a viscous oil film. The initially symmetric flow became asymmetric with time as the water core shifted off centre and also the waves at the oil-water interface became asymmetric. A linear stability analysis for core-annular flow was also performed. A characteristic equation which predicts the growth rate of perturbations as a function of the core radius, Reynolds number, and viscosity and density ratios of the two phases was developed. Also, two micro cells for gas solubility measurements in oils were designed and constructed. The blind cell had an internal volume of less than 2 ml and the micro glass cell had a volume less than 100 µl. By minimizing the cell volume, measurements could be made more quickly. The CO2 solubility was determined in bitumen and ashphaltene-free bitumen samples to show that ashphaltene has a negligible effect on CO2 solubility.

Classically 13% Cr is required for stable passivity of steel in acidic and neutral solutions. Some authors (Mansfeld, Fujimoto) have published potential cycling procedures that generate thick Cr-rich films. Fujimoto cycles right to the transpassivity potential and back in H2SO4 solution. Our idea is to work close to the reactivation potential where the passive film (Fe2O3) is reductively dissolved to Fe2+. While using an equimolar acetate buffer (pH 4.7), we have obtained new insights into the reactivation process. It is under a kind of thermodynamic control, in that the film cannot be reduced, and the metal cannot be dissolved, faster than would exceed the equilibrium concentration of Fe2+ at the electrode surface. Reductive dissolution leads to gel-like Cr-rich film, but Fe dissolution occurs through it, if formed in a single step. However alternating formation and reductive dissolution of a Fe-rich film assist the formation of a more robust Cr-rich film