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O biossólido pode ser um valioso recurso ao ser utilizado em solos agrícolas; porém, um dos principais problemas de sua utilização é a presença de patógenos que podem disseminar doenças. Os principais patógenos presentes no biossólido são vírus, bactérias, protozoários e helmintos. Dentre os patógenos existentes no biossólido, os ovos de helmintos são os mais resistentes à inativação térmica e, para helmintos, os ovos de Ascaris são utilizados como indicador desses parasitas devido à comum ocorrência e resistência térmica. Dentre os processos efetivos existentes para inativar patógenos do biossólido - compostagem, secagem e tratamento térmico, digestão aeróbia termofílica, irradiação com raios beta e gama e pasteurização - este último, utilizando como fonte de calor o vapor saturado gerado a partir da queima do metano produzido em digestores anaeróbios de ETEs convencionais, é um processo de tecnologia simples, com baixo custo de implantação e operação e necessita de pequena área para implantação, sendo indicado para grandes metrópoles de países em desenvolvimento. A inativação térmica de helmintos do biossólido é o objetivo deste projeto de pesquisa. São estudadas as cinéticas de inativação térmica de ovos de Ascaris suum em água e em biossólido digerido, utilizando-se reator batelada aquecido diretamente com vapor saturado. Aplicando-se o método integral, foram determinadas a ordem das reações, as constantes específicas de morte térmica e as energias de ativação. Os ovos de Ascaris suum utilizados no trabalho foram obtidos do útero de fêmeas adultas, e o método de Yanko foi empregado para recuperação dos ovos do biossólido digerido. A inativação térmica de ovos de Ascaris em água e em biossólido digerido em processo contínuo também foi estudada por meio da modelagem matemática de um reator tubular. Os modelos propostos foram o reator tubular isotérmico com perfil de escoamento não ideal e o reator tubular com perfil axial de temperatura e escoamento tubular ideal. O primeiro foi o que melhor ajustou-se aos dados experimentais. / Biological sludge can be a valuable resource for agricultural soil conditioning. However, an important obstacle for its use is the usual presence of pathogenic organisms, capable of disease dissemination. The main occurring pathogens are virus, bacteria, protozoa and helminth. Helminth eggs are very resistant to thermal inactivation. The Ascaris lumbricoids sp. are by far the most conspicuous and resistant among helminths, reason why they have been chosen as indicator organisms for this research. The main available systems to inactivate sludge pathogens are composting, drying and thermal treatment, anaerobic thermofilic digestion, beta and gamma radiation, and pasteurization. Pasteurization through application of saturated steam, produced from burning of methane gas, generated in anaerobic digestors is a very simple technology involving low capital costs and needing relatively small areas for implementation. It can be a valuable technology to attend conditions prevailing in large metropolitan areas of industrializing countries. Thermal inactivation of helminth eggs in water and sludge is the main purpose of this investigation. Kinetics studies of thermal inactivation by saturated steam was performed using batch reactors. Application of the integral method has allowed for the determination of reaction orders, the specific constants of thermal die away as well as the activation energies. The helminth eggs (Ascaris suum) utilized have been obtained from uterus of adult females and the Yanko method was utilized for the recovery of eggs from the digested sludge. In the same way the thermal inactivation of Ascaris eggs in water and in digested sludge has been performed in continuous process by mathematical modeling of a plug flow reactor. The proposed models were the isothermic plug flow reactor with a non-ideal flow profile and with an axial temperature profile and ideal flow. The experimental data has shown a better adjustment to the isothermic plug flow reactor.

The advancement in computational thermodynamics can help researchers to test their hypotheses regarding complex steelmaking operations in a more quantified manner. The main aim of the current work was to use develop a kinetic model that can predict changes in steel, slag and inclusions during ladle refining and use this model as a tool to develop better understanding of the steelmaking process itself. The important reactions during ladle refining are: steel-refractory reaction, slag-refractory reaction, flotation of inclusions to slag, steel-inclusion reaction, steel-slag reaction and inclusions originating from slag. The chemical reactions between two phases were considered to be mass transfer controlled. The macro-processing feature in FactSage was used to do multiple equilibrium calculations and calculate the change in steel, slag and inclusion composition. Targeted experiments and industrial trials were conducted to find model parameters. For laboratory experiments, the rate of magnesium-transfer to oxide inclusions in steel due to steel-crucible and steel-slag reaction was studied. It was concluded that the presence of spinel layer on MgO crucible at the steel-crucible reaction can help in significantly reduce the rate of Mg pick-up due to steel-crucible reaction. For industrial trials, a comparison between the rate of steel-slag reaction and inclusion flotation rate showed that the steel-slag reaction could be significantly slowed due to slag inhomogeneity. The kinetic model was also used to identify artifacts in steel and slag sampling during ladle refining. One of the main limitations of the kinetic model was the over-prediction of calcium pick-up in steel due to steel-slag reaction. Induction furnace experiments were conducted using MgO, ZrO2 and CaO crucible with different slag composition and silicon concentration to study the extent of calcium pick-up due to steel-slag and steel-crucible reactions. The steel-CaO crucible equilibrium experiment was used to estimate Ca-O interaction parameter. The equilibrated steel was reoxidized with known amount of oxygen to allow all the dissolved calcium to precipitate as oxide inclusions. Inclusion analysis of sample taken after reoxidation was used to estimate dissolved calcium in steel. The measured dissolved calcium was used to estimate Ca-O interaction parameter. A private database for liquid steel was created in FactSage and used for kinetic modeling of laboratory scale steel-slag-crucible experiments. The use of private database for kinetic model helped in avoiding excess calcium pick-up in steel due to steel-slag reaction. However, the model and database should be tested for conditions where significant calcium pick-up is experimentally observed. In the present work, the inclusion removal was assumed to be first order reaction with fixed rate constant. In practice, the inclusion removal is expected to be a more complicated process of agglomeration and flotation. Similarly, the steel-inclusion reactions were considered in equilibrium for each time step of calculation. Sometimes, the composition difference inside single inclusions was found. Some characterization tools were used that could be useful in future to study the agglomeration of inclusions and composition differences inside single inclusion. The agglomeration behavior of inclusions at the steel-argon interface inside confocal laser scanning microscope was compared to the agglomeration in bulk samples from laboratory and industrial steel samples. The size and morphology of inclusion clusters were studied using X-ray micro CT. The composition and morphology of single inclusion was studied using focused ion beam methods: Ga-FIB instrument and plasma-FIB instrument.

Abstract The tightening environmental legislation and technological development in automotive engineering form a challenge in reactor design of catalytic reactors for automotive exhaust gas abatement. The catalytic reactor is the heart of the exhaust aftertreatment processes, but it can be seen also just as one subsidiary part of vehicles. The aim of this work is to reveal applicable kinetic models to predict behaviour of the particular catalysts and to establish guidelines for modelling procedures and experimentation facilitating catalytic reactor design, especially in the field of automotive exhaust gas abatement. The studies in this thesis include catalyst kinetics with synthetic exhaust gas composition in stoichiometric and net oxidative conditions, DRIFT measurements, and the warm-up of three-way catalysts in real conditions. Knowledge on surface concentrations facilitates kinetic model construction and discrimination. For example, identification of even semi-quantitative surface concentrations may lead to a successful falsification of incorrect kinetic model candidates. Especially, that is clearly seen in cases where models predict the same kind of gas phase behaviour but different kinds of surface concentration profiles. The transient kinetic experiments could give a hint on predominant reaction mechanism, support quantifying of the adsorption capacity and reveal the impact of surface phenomena on reactor dynamics. The level of model complexity should be adapted depending on the purpose of the model. For example, it is mostly convenient for reactor design purposes to perceive only one type of active sites even in a case of mechanical mixture of different catalytic materials; whereas the optimisation of catalyst content demands the management of every prominent site type separately. Or, when a catalytic material has been selected, the stationary kinetic model is, in most cases, adequate for the catalytic converter design and structural optimization for warm-up conditions.

An integrated approach to the design of potential rutheniun-based metathesis catalysts is described, in which closely defined synthetic forays provide the focus and rationale for detailed computational and mechanistic studies. The ground-state geometry of a 1st-generation Grubbs catalyst has been explored at the molecular mechanics, semi-empirical and DFT levels, and the resulting structures have been shown to compare favourably with literature data and with the structure of a known crystalline analogue. The DMol³ DFT code has also been shown to represent accurately both the geometry of the corresponding co-ordinatively unsaturated monophosphine derivative, and the ligand dissociation energy associated with its formation. A DFT free-energy profile of the degenerate metathesis of ethylene has been generated, using a truncated model of the 1st-generation Grubbs catalyst, permitting location, for the first time, of the three expected transition states and providing new information regarding the rate-determining step. DFT methods have been used to facilitate the design of a tridentate camphor-derived ligand for use in the construction of a novel Grubbs-type catalyst. The phosphine ligand dissociation energy of the putative catalyst and the ethylene metathesis energy profile of a truncated model have also been studies at the DFT level. The attempted synthesis of the proposed ligand proceeded via a novel 8-bromocamphoric anhydride intermediate and afforded several unexpected and novel products, including a cisfused γ-Iactone, and a bromo camphoric acid derivative. Single crystal X-ray analysis of the latter reveals a chiral, polymeric H-bonded packing arrangement, rendering it suitable for chiral inclusion studies. Computational methods, including the GAUSSIAN-based GIAO NMR prediction technique, were used to support the structural characterisation of the novel camphor derivatives. DFT-Ievel computational analysis of the C-8- and C-9 bromination of camphor has afforded theoretical insights which permit the reconciliation of two earlier empirical explanations regarding the regioselectivity of these transformations; moreover, the theoretical results suggest that a third, previously disregarded factor, plays a significant role. A coset analysis, in conjunction with DFT-Ievel energy profiling, has also been used to resolve conflicting opinions regarding the origin of the major byproduct. Computed electronic parameters (CEP's) have been calculated for the anionic ligands involved in a series of 2nd-generation Grubbs-Hoveyda-type catalysts, and used to explain some apparently anomalous trends in catalyst activity. A linear relationship between ligand CEP's and selected ¹H NMR chemical shifts has also been demonstrated and used to identify a transient ruthenium complex in solution. The ability of the malonate di-anion to bind to ruthenium in a bidentate manner has been explored and demonstrated, under suitable conditions. DFT methods have been used to design and assess the ruthenium-chelating potential of a novel tridentate malonate derivative. A synthetic pathway to this ligand has been designed and several novel heterocyclic intermediates have been isolated and characterised. An NMR-based kinetic study of the Grubbs-catalysed self-metathesis of l-octene has been completed, and the effects of temperature, concentration and solvent variations on the kinetic parameters have been studied. Application of the Guggenheim method and a simplified mechanistic model has permitted the accurate calculation of pseudorate constants for the initiation and, for the first time, the propagation phase of the reaction. Theoretical studies of this reaction at the DFT and molecular mechanics levels have been shown to support previous assumptions regarding the selectivity and temperature-dependence of metallacycle formation.

The reduction of osmium tetroxide by a series of alcohols was studied spectrophotometrically. The reaction was observed to occur in two steps, unlike previously reported studies on this reaction. The identities of both reactants and products were established via a range of techniques. Equilibrium and kinetic data were gathered and reaction models were evaluated using equilibrium and kinetic modelling software. The following complexation reaction model emerged that simulates both the equilibrium and kinetic data. Os(VIII) + RCH2OHOs(VI) + RCHO2 Os(VIII) + Os(VI)k+2k1Complexk-2 Conditional rate constants and equilibrium constants were generated. Rate constants for the alcohol reactions were correlated with the Taft σ* constant. The ρ* value obtained (-1.4) is consistent with a hydride transfer mechanism coupled with synchronous removal of the hydroxyl proton. The identity of the osmium(VIII)-osmium(VI) complex has been suggested. Thermodynamic parameters were also reported. The rate constants for benzyl alcohol and 2-chloroethanol deviated from those predicted by the Taft plot. An explanation of enhanced resonance effects is offered for benzyl alcohol and an alternative reaction mechanism, involving proton abstraction, is offered for 2-chloroethanol. The reaction of the oxidation products of alcohols, namely ketones, with osmium tetroxide produced rate constants that were, perhaps surprisingly, far larger than those of the alcohols. A reaction mechanism for the oxidation of the ketones is suggested, which involves the enolate ion as the reactive starting reagent.

The Arrhenius parameters have been measured for the addition of the ethyl radical to methyl acrylate and its mono-methyl derivatives, methyl methacrylate, methyl cis-crotonate and methyl trans-crotonate. The energy of activation for each of these derivatives is significantly greater than for methyl acrylate, probably because of the adverse polar effect introduced by the methyl group. The activation energy for the addition to methyl methacrylate appears to be lower than for either the cis- or trans- methyl crotonate. This can probably be attributed to the fact that the ∝-methyl group can more effectively stabilise the adduct radical resulting from the addition of the ethyl radical to the methyl methacrylate, than the β-methyl group can in the case of crotonates. The pre-exponential factor is significantly smaller for each of the methyl crotonate isomers than for methyl methacrylate; partial shielding of the β-carbon atom of methyl crotonate is thus expressed by a steric factor rather than by an energy term. In terms of the rate constant for the addition reaction over the range 70°C to 160°C, methyl trans-crotonate is significantly more reactive than methyl cis-crotonate, and each isomer is only about one tenth as reactive as the vinyl compounds, methyl acrylate and methyl methacrylate, in which the site of radical attack is comparatively unobstructed. The cis-trans isomerisation of methyl crotonate is photo-sensitised by diethyl ketone illuminated by 3130 Å radiation in the gaseous phase; a mechanism of triplet state energy transfer is proposed for the process below 200°C; above 200°C an alternative mechanism involving the reversible addition of the ethyl radical to the double bond becomes the predominant process of isomerisation. / Science, Faculty of / Chemistry, Department of / Graduate

The kinetics of the hydrogen reduction of aqueous cupric perchlorate and sulphate solutions were studied at 160°C and 5 to 10 atm hydrogen pressure. In sulphate solutions the observed rates were consistent with a rate law, derived from previously proposed mechanisms, that has the form [ Equations omitted ] The rate constants of the hydrogen activation steps of the reaction are represented by k₁and k₃ which reflect the activation rates by Cu'' and Cu' respectively and have the values 3.2 X 10¯³M¯¹sec¯¹ and 6.4 X 10¯²M¯¹sec¯¹ at 160°C. The ratios of the back- to net forward-reaction rate constants are k-₁/k₂ for the Cu'' activation step and k-₃/k₄ for the Cu' activation step. These have values of approximately 0.13 and 0.45 respectively at 160°C. In perchlorate solutions the rates were also consistent with the rate law applying to sulphate solutions if a necessary correction due to perchlorate decomposition was taken into account. In this system the second term of this rate law was found to be much smaller and more difficult to resolve. For the first term the value of k₁ was found to be 6.7 X 10¯³M¯¹sec¯¹ at 160°C and the value of k-₁/k₂ was 0.51. Exchange experiments with deuterium in place of hydrogen were also done. These gave rates consistent with previously proposed mechanisms, but in perchlorate solutions much higher exchange rates were observed than in sulphate solutions. The indicated value of k₃ is approximately the same in perchlorate as in sulphate solutions and the indicated value of k-₃/k₄ is much greater in perchlorate solutions. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

The kinetics of the oxidation of hydrazobenzene by iodine in buffered ethanol-water solutions were studied between 0°C. and 25°C. A measurable rate was obtained by depressing the iodine concentration by the addition of excess iodide, so that most of the iodine was transformed to triiodide. The effects of initial concentrations, acidity, solvent composition and buffer ionic strength were determined, as well as that of adding quinone and several metal salts. Both iodine and triiodide were found to oxidize hydrazobenzene, but iodine Is about 100,000 times more reactive than triiodide. [formula omitted] The kinetics suggest that both reactions have a simple bimolecular mechanism, expressed by the rate law [formula omitted] The constants k₁ and k₂ were evaluated in 60 volume per cent ethanol and buffer ionic strength 0.31 as [formula omitted] In connection with this work it was found necessary to evaluate the equilibrium constant of formation of triiodide in the solvents used. The heat and entropy of formation from iodine and iodide in 60 volume per cent ethanol were found to be -9.5 ± 0.5 kcal.mol.⁻¹ and -13.2 e.u. respectively. / Science, Faculty of / Chemistry, Department of / Graduate

Class of 2008 Abstract / Objectives: A novel method of predicting vancomycin trough levels at steady state was studied to determine whether it could effectively predict vancomycin trough levels compared to an established predictor method (Matzke). Methods: Adult patients who received at least two consecutive doses of vancomycin and had at least one reported vancomycin trough at steady state were considered. Data extracted and analyzed included patient gender, age, weight, height, and serum creatinine as well as vancomycin dose and interval, number of consecutive doses prior to the trough, time between trough and preceding dose, and measured vancomycin trough level. This data was applied to each of the prediction methods to determine how accurately they predicted actual measured vancomycin trough levels at steady state. Results: Data from 103 patients was analyzed. Vancomycin trough predictions using the Bergstrom method averaged 12.2 mg/dl, with a standard deviation of 3.4. The average actual trough concentration was 10.7 mg/dl with a standard deviation of 3.9, while the Matzke method predicted an average trough concentration of 19.2 mg/dl with a standard deviation of 8.6. Predictions made using the Bergstrom Method were not significantly different than the actual trough concentrations (p = 0.91). The Bergstrom method predicted concentrations within 25% of actual concentrations 42% of the time and within 50% of actual concentrations 78% of the time. Conclusions: The Bergstrom method was a more reliable predictor of vancomycin trough concentrations than the Matzke method in this patient population. Although more research is needed, the Bergstrom method may prove to be a useful tool for pharmacists to predict vancomycin trough concentrations quickly and with relative accuracy for individual patients.