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<p>Ion exchange equilibrium data can be used to predict the viability of a proposed process. Ion exchange equilibria have been studied considerably since the 1950's but the complexity of the basic research has tended to reduce its direct usefulness to the practising engineer. This research has been undertaken to determine if a moderately simple method of experimentation and analysis could be applied to predict ion exchange equilibria to within limits of accuracy acceptable to engineers.</p> <p> The first step in the research was to develop a simple mathematical model for a binary system to calculate the selectivity coefficient and resin capacity from batch experiments. The model was successfully applied for the exchange of Na+ with five heavy metal ions: Ni²⁺; Cu²⁺; Cd²⁺; Pb²⁺ and Zn²⁺ on a typical commercial resin (Dowex HCR-W2). The binary parameters were then used to predict the equilibrium values for several ternary systems. From these ternary experiments, it was determined that binary data can be used to predict ternary systems if the selectivity coefficients of the two ions involved are either almost equal or differed by at least a factor of five. A kinetic effect was proposed to explain the discrepancies observed between the predicted and experimental values for the intermediate ratios of selectivity coefficients of the involved ions, although further work is required to confirm this hypothesis.</p> <p> Several packed bed experiments were performed to check some of the results from the binary and ternary system experiments and as exploratory work for future research. These experiments confirmed the capacity data calculated from the binary system experiments and were consistent with the trends observed in the ternary system experiments.</p> / Thesis / Master of Engineering (ME)

Detonation waves in gases are very complex, involving a highly transient cellular structure and a turbulent reaction zone coupled with transverse shocks. The role of out-of-equilibrium phenomena in these waves remains unclear despite extensive research on the underlying physics. On the small scales, translational non-equilibrium associated with shocks, as postulated by Zel’dovich, may significantly affect the chemistry, and these effects are not yet fully understood. Similarly, very fast chemical processes may involve out-of-equilibrium effects due to local energy release that has been postulated by Prigogine. On larger scales, detonation waves display a cellular structure and are supported by turbulent combustion. The present thesis aims to quantify the importance of these three out-of-equilibrium effects on ignition, wave amplification, and diffraction limits of detonations. First, the role of translational non-equilibrium in reactive dynamics in the thermal explosion problem is investigated using molecular dynamics (MD) simulations and continuum models. Ignition delays are calculated and compared with rates from kinetic theory. MD results show agreement with the Prigogine and Mahieu corrections to the reaction rate evaluated from kinetic theory assuming a Maxwell-Boltzmann distribution. Accounting for the departure from translational equilibrium was found to reduce the ignition delay by up to 30% specifically at high activation energies. However, at low activation energies, the standard equilibrium rate shows a longer delay by up to 60%. The molecular dynamics simulations reveal that translational non-equilibrium effects accelerate activated exothermic reactions, referred to as “molecular hotspots”. The second part of the study focuses on the impact of thermal non-equilibrium and its coupling with reactive kinetics in shock-to-detonation transitions in gases. Results suggest that shock-induced ignition and transition to detonation involve non-equilibrium reactions that overlap with the shock structure, showing strong translational non-equilibrium with reactive fingers. Comparison with continuum simulations using different approximations reveals that shock amplification rate and transition to detonation are approximately twice as fast as predicted by conventional Euler hydrodynamic models, despite evidence of non-equilibrium. A Navier-Stokes model with hard sphere transport properties effectively captures the acceleration process, indicating significant implications for modeling gaseous detonations with fast reactions and strongly coupled pressure wave dynamics and reactivity in the detonation structure. In the last part of the thesis, the 3D hydrodynamic structure of cellular detonations is modeled by a global 1D mean hydrodynamic average model. Transport properties are artificially increased to account for the high-speed behavior resulting from fast turbulent diffusion. The existence of steady state Navier-Stokes detonation structure, as studied by Wood, is critically reviewed for this purpose and compared with transient calculations. Observations reveal that in the hyper-diffuse model, the shock and reaction zone overlap, resulting in a thickened reaction zone. The 1D model is used to study diffraction dynamics, with critical diffraction occurring when the tube diameter approaches the hydrodynamic reaction zone thickness. After diffraction, the complex viscous detonation structure separates, resulting in a rapid flame transitioning into a weak detonation. The conclusion of the present survey on the role of out-of-equilibrium effects on detonation dynamics suggests that non-equilibrium ignition due to molecular hotspots may give rise to corrections on the reaction rates by at most a factor of two. The coupling of exothermic reactions with the non-equilibrium structure of shock waves also predicts rates of shock amplification different by a factor of two from the standard Euler model for ignition, but accounting for the diffusive effects brings the MD and continuum predictions into closer agreement. Similarities with the out-of-equilibrium hydrodynamic structure of detonations are discussed.

Invasive plant species are an increasing global threat to native biodiversity. Effective management depends on accurate predictions of their spread. However, modelling the geographic distribution of invasive species, particularly with methods like correlative species distribution models (SDMs), is challenging. SDMs operate under the assumption that species are in equilibrium with their environment (i.e., they occur in all suitable environments); this assumption is more likely to be violated for a species that is still in the process of colonizing suitable environments. SDMs also assume that environmental constraints are the most important factors determining a species' distribution. However, these assumptions are not commonly assessed, and when violated can have consequences for model reliability. I investigated SDM performance and equilibrium in the invasive Vincetoxicum rossicum vine in northeastern North America. Vincetoxicum rossicum has a long, detailed history of occurrence records in its invaded range, which enabled me to observe trends in equilibrium and model performance over a relatively long time scale. I tested the hypotheses that: 1) invasive species approach equilibrium in environmental and geographic space over time; 2) SDM performance will increase as V. rossicum approaches environmental equilibrium; and 3) range expansion in the early stages of an invasion is primarily a function of dispersal rather than environmental constraints, while the reverse is true in later stages. I found that V. rossicum has reached equilibrium in environmental space, but is still expanding its geographic range. SDM performance was poor in the first 30 years following introduction, but then improved as V. rossicum approached environmental equilibrium. SDMs were outperformed by spatial dispersal models in the earliest time period, however, the reverse was true for all subsequent time periods. Overall, these results suggest that V. rossicum’s distribution is becoming more stable and more predictable over time and that models built using the most recent data for this species, will be the most transferable across time and space. Additionally, my findings highlight the need for researchers modelling invasive species’ distributions to consider the inherent assumptions, biases, and unique features related to SDMs and SDMs of invasive species.

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Intravenous admixtures consisting of one or more drug formulations, diluted in a large volume of intravenous solution, are used extensively in current medical practice. Development of reliable methods to predict the compatibility of the admixture components is essential as a guide for their selection. Because the majority of the reports published, to date, have used a visible change as the criterion for judging compatibility, it was the purpose of this study to demonstrate the use of spectrophotometric analysis to detect the occurrence of chemical interactions between two components of an intravenous admixture.

At high temperatures, the properties of aqueous electrolyte systems differ markedly from those at 25°C. For mixed-electrolyte dilute solutions at high temperatures, the degree of ion-association is sufficiently large that the association equilibrium must be incorporated in any model describing the solutions. These association reactions usually do not occur to a measurable extent at room temperature. Oscarson and co-workers have designed a correlation model based on the excess Gibbs energy which can correlate log K and ∆H values as well as the heats of dilution for aqueous electrolyte systems as a function of temperature (T) and ionic strength (I) from 275 to 350°C. Use of calorimetric data to develop the model has been shown to be more accurate than using ∆dilH values from the variation of log K with temperature because one less differentiation with respect to temperature is required. In this study, the computer program developed by Oscarson and co-workers has been modified by incorporating the IAPWS-95 water equation of state and Archer and Wang's correlation of the dielectric constant of water into the excess Gibbs engergy model. The difference between the present work and prior work is that it uses a more accurate equation of state for water, a more accurate dielectric constant for water and the best equilibrium constants currently available. The properties of water play a very important role in the calculation of ∆dilH values, and the modified program developed here using improved water equations is shown to be superior to the previous one. The results of this modified model were tested by comparing the predicted heats of dilution with experimental measurements from Oscarson's work. These experimental data cover the range from 523.15 K to 623.15 K and 103 bar to 128 bar. The nominal concentrations of the solutions used for the ∆dilH experiments were 0.25, 0.5 and 1.0 m. Equilibrium constants K for Na2SO4 (aq), H2SO4 (aq), NaAc (aq), and HCl (aq) association were taken from conductivity values measured by Wood and co-workers using a flow conductance apparatus. These log K values were used to compare the predicted log K values from Oscarson's model and those from this modified model.

This thesis focuses on using mass spectrometry-based techniques for characterizing the structure and behavior of cucurbituril complexes in the gas phase. Both solvent and counter ion effects can be completely eliminated in the gas phase and the intrinsic interactions in the system are directly shown in the experimental results. Chapter 1 introduces the structures, properties and host-guest chemistry of cucurbituril, and FTICR mass spectrometry including instrumentation, performance and working principles. Two mass spectrometry-based methods for supramolecular characterization, sustained off-resonance irradiation collision induced dissociation (SORI CID) and ion molecule equilibrium measurements, are also discussed in this chapter. Chapter 2 characterizes the dissociation and reaction behaviors of the complexes formed by cucurbit[5]uril (CB5) and primary monoamines [CH3(CH2)nNH2, n = 0-7] as well as similar studies of decamethylcucurbit[5]uril (mc5) in the gas phase. This study probes host-guest interactions between the neutral cucurbituril host and alkyl chains of varying length. All the cucurbit[5]uril and decamethylcucurbit[5]uril complexes have external binding. The dissociation thresholds of the complexes suggest that the optimum monoammonium chain length for binding CB5 in the gas phase occurs for n = 2, whereas for mc5 the optimum is n = 0. Reactivity studies of CB5 and mc5 complexes indicate the highest binding affinity appears at n = 6 for CB5 and n = 5 for mc5. Chapter 3 investigates the complexes formed by cucurbit[6]uril and primary monoamines using energy resolved SORI CID methods and ion molecule equilibrium measurements. The fragmentation data, branching ratios for the various channels, and the reactivities of the complexes suggest the complexes have the monoammonium threaded through the cavity of CB6 forming a pseudorotaxane architecture. Reactivity studies of complexes of cucurbit[7]uril reveal behaviors distinctive from CB5, mc5 or CB6, which suggests both internally-bound and externally-bound structures are present in CB7 complexes.

Biodiesel is produced from vegetable oils through transesterification. Triglyceride mixtures extracted from oilseed feedstocks are upgraded by reaction with an alcohol in the presence of a catalyst to produce fatty acid esters. This reaction produces a mixture of esters, glycerin, alcohol, and catalyst. Separation of the fatty acid esters (biodiesel) and glycerin can be accomplished through liquid-liquid extraction by water addition. Designing liquid-liquid extraction with water as the solvent requires ternary liquid-liquid equilibrium data for mixtures of water, glycerin, and fatty acid esters. Ternary mixture LLE data have been experimentally measured for several of these systems. Those measured include mixtures with the methyl esters of lauric, myristic, palmitic, stearic, and oleic acids. Data were collected at atmospheric pressure and 60°C. These ternary systems have been correlated using the NRTL equation. These data and correlation parameters can be used to improve separations efficiency in trans-esterified biodiesel fuels.