<p> A noninvasive method using fluorescence quenching (FQ) to determine the conditional stability constants (logK') for aluminum with naturally occurring organic ligands has been developed. The method utilizes the Stern-Volmer equation to interpret data from ligand fluorescence suppression by aluminum. The total ligand concentration can also be determined using the measured stability constant and the Ryan-Weber equation. The method has been validated with the model ligand salicylic acid; logK' was found to be 3.5 ± 0.01 vs. 4.0 from the literature. The method was applied to the reference ligand Armadale fulvic acid and chemically realistic values were obtained. In addition, the expected trend of increasing stability constant with decreasing pH was observed. The method was further validated by determining the stability constant for Armadale fulvic acid using an independent technique, PCV colourimetry; the results agreed very well logK' = 4.7 vs. 4.65 for FQ analysis. Application of the method to whole filtered beaver pond water showed an increasing trend in the stability constant as the dissolved organic carbon (DOC) decreased. The Log of the stability constants were 3.15 ± 0.03, 3.26 ± 0.03, and 3.63 ± 0.02 for DOC concentrations 23, 14, and 10 ppm respectively. The method was also applied to size fractionated waters form lake Skjervatjern in Norway and the expected trend of increasing stability constant with increasing molecular weight was observed.</p> / Thesis / Bachelor of Science (BSc)

Inorganic nanoscale clusters have garnered significant interest for many practical applications within the fields of materials chemistry, inorganic chemistry, geochemistry, and environmental chemistry. However, the fundamental inner workings of how these materials interact in the solid state and solution continues to be a very elusive problem for scientists. My dissertation focuses on taking non-traditional approaches and characterization techniques to further understand the dynamic interactions of some of the aforementioned clusters. Chapter I is a comprehensive survey and perspective on selected characterization techniques used to study Group 13 aqueous nanoscale clusters and other polyoxometalates in solution. Chapter II focuses on utilizing Raman spectroscopy, infrared spectroscopy, and quantum mechanical computations to unambiguously identify Group 13 tridecameric species in the solid state and aqueous solution. Chapter III discusses the first instance of transmetalation of aqueous aluminum clusters via salt addition of In(NO3)3 in aqueous or methanol. Chapters IV and V explore the effects that aprotic and protic solvents can have on the solution speciation of the flat aluminum tridecamer. Chapter VI discusses the utility of using electrochemically synthesized gallium tridecamer and its functional use as a thin film semiconductor. Chapter VII describes a unique graduate level chemistry course designed to allow students to conduct and generate publication-worthy research within the timeframe of the course. Chapter VIII ventures out beyond the group 13 cluster and introduces techniques used to study the formation and stability of aqueous hafnium clusters. Chapter IX details the synthesis and characterization of rhombic structured copper clusters in the solid state. Finally, chapter X highlights my unfinished projects that can propel future research within the lab. This dissertation includes previously published and unpublished co-authored material.

Many Canadian water treatment plants supplied by surface waters of the Canadian Prairie and Shield have elevated concentrations of trihalomethanes (THMs), which exceed the provincial standards. These water sources are characterized by elevated levels of dissolved organic carbon (DOC) and varying levels of calcium hardness, which causes a challenge for the removal of THMs precursors. The objective of this study was to investigate the effect of two treatment methods: chemical coagulation and pre-ozonation-coagulation on the removal of DOC as the main THMs precursor. Surface waters typical for the Canadian Prairie and Canadian Shield were used in the experiments which includes Assiniboine River, Red River, and Rainy River. The effects of different experimental conditions such as coagulant dose, coagulant type, and solution pH as well as ozone dosage on THMs removal were investigated. The structural and chemical characteristics of natural organic matter and isolated humic substances, before and after the reaction with ozone, were studied using spectroscopic techniques. The results illustrated that the quality of source water (DOC characteristics, concentration of water DOC and Calcium) has a significant impact on THMs reduction by chemical coagulation and ozonation. Coagulation results showed that reduction of total DOC does not guarantee THMFP reduction and chemical coagulation should be optimized to remove the hydrophobic acid fraction which forms most THMs. The removal of DOC by aluminum-based coagulants was affected more by the concentration of polymeric and colloidal aluminum speciation. This finding is especially important for plants supplied by high alkalinity waters where pH adjustment is a serious challenge. The effect of pre-ozonation on coagulation varies depending on the concentration of calcium, which has the ability to form complexes with DOC compounds promoting their removal in coagulation. For the surface water with high levels of organic carbon and calcium hardness, ozonation prior to coagulation was beneficial in terms of DOC reduction. However, it showed the opposite effect on water with high levels of DOC accompanied with low level of calcium hardness. Spectroscopic results showed that ozonation of NOM and humic substances cause a significant reduction of aromatic and highly conjugated compounds (constituting primarily the hydrophobic acid fraction). / February 2016

Poor settling of solids increases land requirement for tailings containment and imposes severe constraints on the water balance. Consequent to these considerations, the alternating current electrocoagulation (AC/EC) technique emerged as a candidate for enhancing the settling behaviour of suspensions in the mineral, coal and oil sands industries. Hence, a fundamental study of AC/EC was undertaken with aluminum electrodes. Ground silica (d50 = 20 m), which formed a stable suspension, served as the model tailings solid at 5.0 wt % in water. The AC/EC process consisted of two developmental stages: coagulation, marked by pH decrease in the silica suspension; and floc growth, characterized by pH increase from the minimum (i.e., the end of coagulation). AC/EC enhanced the initial settling rate of silica by over three orders of magnitude, and exhibited remarkable flexibility by virtue of the wide range of process parameters that could be optimized. For example, AC/EC can be operated in either the indirect or direct mode. The settling behaviour of bentonite (estimated d50 < 1 m) was more enhanced by indirect AC/EC, while that of silica benefited more from direct AC/EC. Any condition that increased aluminum dosage (e.g., current, retention time), increased the initial settling rate of silica. Over the feed water pH range of 3.0 to 9.1, AC/EC was effective in enhancing the settling behaviour of silica. AC/EC was also effective over a wide range of temperatures (23 to 85C). High electrical energy demand by AC/EC was observed throughout this study. Its optimization was beyond the scope of this work. Dilution of a sample of Syncrude mature fine tailings (MFT) to 4.6 wt % solids sustained a stable suspension. Settling occurred after AC/EC treatment, a crystal-clear supernatant resulted and bitumen was recovered as froth. Entrained solids were easily spray-washed from the froth with water. The settling behaviour of a Luscar Sterco fine coal tailings sample was not augmented by AC/EC, possibly due to contamination by the companys own electrocoagulation operation. After having been stored dry for more than a year, electrocoagulated silica was an effective coagulant for as-received silica and Syncrude MFT. / Chemical Engineering

No description available.