Thesis (Ph.D.)--McMaster University (Canada), 1995. / Source: Dissertation Abstracts International, Volume: 57-03, Section: B, page: 1870. Adviser: D. A. Thompson.

Thesis (M.S.)--Texas State University--San Marcos, 2009. / Vita. Appendices: leaves 62-65. Includes bibliographical references (leaves 66-67). Also available on microfilm.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2010. / Title from PDF t.p. (viewed July 20, 2010). Additional advisors: Mian M. Abbas, Renato P. Camata, Sergey B. Mirov, Thomas M. Orlando. Includes bibliographical references (p. 111-117).

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 79-81). Also available on the World Wide Web.

[pt] O presente trabalho descreve o desenvolvimento e avaliação de um sistema de dessorção térmica ex situ desenhado na PUC - Rio destinado a remediação de solos contaminados por hidrocarbonetos de petróleo. Trata-se de um sistema modular que emprega altas temperaturas para volatizar o contaminante do meio poroso. O principal módulo do sistema consiste de caixas metálicas onde o solo escavado é disposto e submetido ao tratamento. No interior de cada caixa são inseridas resistências que permitem a aplicação de altas temperaturas através da rede elétrica. A temperatura durante o ensaio é controlada por um sistema que permite a aplicação de rampas e patamares. O sistema também possui uma unidade de aeração que evita o coqueamento do material a ser tratado. A avaliação do sistema foi realizada com o tratamento ex situ de um solo contaminado oriundo de um antigo posto de serviços no Bairro do Grajaú, Rio de Janeiro. O sistema mostrou ter um bom desempenho reduzindo a contaminação do solo a valores abaixo do limite de detecção do analisador de gases Thermo modelo GasTech Innova SV. O tratamento realizado apresentou um custo de R$ 0,43 por quilograma de solo tratado, valor este bem abaixo do cobrado por unidades de incineração do Estado do Rio de Janeiro (i.e., cerca de R$ 3,00/kg). / [en] This dissertation describes the development and assessment of an ex situ thermal desorption system designed at PUC - Rio aimed on treating petroleum hydrocarbon contaminated soils. The modular system employs high temperatures to volatilize the contaminants presented in the porous media. The main component of this system comprises steel boxes where the contaminated soil is disposed and treated. In each box, electrical resistances are inserted enabling the application of very high temperature. The temperature during testing is controlled by a system that allows the use of ramps and steps. The system also has a unit of the aeration which prevents coking of the material to be treated. The system was assessed employing a contaminated soil excavated from a former gas station in Grajaú, Rio de Janeiro. The system showed a good performance reducing the contamination to levels below the limit detection of a Thermo GasTech Innova SV gas analyzer. The treatment presented a cost of R$ 0,43/kg, well below the average cost charged by incineration units in the State of Rio de Janeiro (i.e., circa R$ 3,00/kg).

The phenomenon of hydrogen embrittlement in steel has been known for over 150 years. Hydrogen-resistant alloys have been developed to mitigate this effect and three types of alloys with optimised structures have been enhanced over the years: nickel alloys, stainless steels, and quenched and tempered martensitic low alloy steels. Nevertheless, those alloys are limited in terms of strength and ductility. The aim of the work presented in this thesis was to design bainitic alloys with hydrogen embrittlement resistance, and with a better combination of strength and ductility than conventional alloys. In the novel alloys, two microstructural features were produced to mitigate the damaging effects of hydrogen: 1. A percolating austenite structure, in which hydrogen diffusion is orders of magnitude lower than in bainitic ferrite. This feature was introduced to impede the ingress of hydrogen through the structure. 2. Iron carbide traps, which can form at the bainite transformation temperature. This feature was introduced to trap diffusible hydrogen and prevent it from causing damage. The alloys, designed with the aid of computer models and phase transformation theory, contained a volume fraction of retained austenite above its percolation threshold, theorised as 0.1, which was proven to form an effcient barrier to hydrogen ingress. The effective diffusivity of hydrogen, measured using an electrochemical permeation technique, was shown to decrease with increasing austenite fraction up to the percolation threshold. It was seen to plateau for austenite fractions comprised between 0.1 and 0.18, and to decrease further for fractions above 0.18. The compositions of the alloys were precisely selected to allow for iron carbides to precipitate during the bainitic transformation reaction. Until the present work, only alloy carbides V4C3, TiC and NbC had been reported to strongly trap hydrogen. The literature was very inconsistent regarding the trapping ability of cementite, with reported trap binding energies ranging from 11 to 66 kJ mol−1. The carbides produced in the alloys were identified as cementite. The cementite fraction was measured to be 0.001 ± 0.0001 for one of the designed alloys, which is the lowest ever reported carbide fraction in steel measured using a simple X-ray diffraction technique. Experimental thermal desorption spectroscopy data were used to determine the binding energy of hydrogen to cementite to be 37.5 kJ mol−1, suggesting that cementite is not a strong hydrogen trap. Further tests performed after room temperature hydrogen degassing displayed insignifcant amount of trapped hydrogen, thus confrming the reversible nature of cementite traps. The comparison of two successive transients using the electrochemical permeation technique confirmed that result. The influence of the heat treatments on the microstructures and on the mechanical properties of the designed alloys was extensively studied. The novel alloys met all the set requirements, and successfully outperformed conventional alloys in terms of strength and ductility. They did not meet the NACE TM0316-2016 standard requirement for operation in hydrogen-rich environments, likely owing to the inadequate trapping ability of cementite. Future work should focus on exploring the possible use of alternative carbides for hydrogen trapping in bainitic structures.

M.Tech. / In this study, ethylene vinyl acetate-fly ash (EVA-FA) composites were explored for the removal of phenols from water. The composites were prepared from EVA and untreated and acid treated fly ash via the melt-mixing technique using a rheomixer. The fly ash was characterised by X-ray fluorescence (XRF), X-ray diffraction (XRD) scanning electron microscopy (SEM) and Brunauer, Emmett and Teller (BET) surface area measurement. Fly ash is composed mainly of SiO2, Al2O3, CaO and Fe2O3. Modified fly ash gave a better specific surface area of 0.4180 m2/g, while 0.0710 m2/g was obtained for unmodified fly-ash due to the disintegration of the outer layer which resulted in smaller particles, hence a larger surface area. EVA-FA composites were prepared from fly ash loadings of 3 to 20% and further characterised by XRD, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and SEM. XRD showed successful incorporation of fly ash into the EVA matrix through the appearance of fly ash diffraction peaks on the EVA-FA composite diffraction pattern. The incorporation of fly ash into the EVA matrix resulted in an improvement in the thermal stability of EVA, but did not have an effect on the melting temperature of the composites. However, a decrease in crystallisation temperature was observed. SEM micrographs revealed uniform dispersion of fly ash particles in the polymer matrix. Adsorption studies were performed using p-chlorophenol (PCP), 2,4,6-trichlorophenol (TCP) and p-nitrophenol (PNP) as model pollutants. An increase in adsorption efficiency of EVA-FA composites was observed as fly ash loading was increased from 3 to 10%. Between 10 and 20% fly-ash loading the removal efficiencies remained constant. The effect of contact time, pH and initial concentration was investigated. Polymer composites prepared from unmodified fly ash resulted in a higher adsorption capacity of phenols. The maximum uptake of PCP was 0.18 mg/g and that for TCP was 0.19 mg/g over a pH range of pH 3 to 5 and after contact time of 8 h. However, the adsorption capacity of 0.30 mg/g for PNP was achieved at pH 5 after a period of 10 h. Equilibrium adsorption data were evaluated using Langmuir and Freundlich adsorption isotherm models. There was no significant difference in the correlation coefficients (R2) from both models for the adsorption of PCP and TCP. However, the equilibrium adsorption data for PNP were better described by the Langmuir adsorption isotherm model. The kinetics data were analysed by pseudo-first-order and pseudo-second-order kinetic models. The pseudo-second-order kinetics model gave better correlation coefficients (> 0.9) for the adsorption of the phenols and the amount adsorbed at equilibrium was comparable to that calculated from the pseudo-second-order equation. Desorption studies were performed using NaOH solution with varying concentrations (0.1 to 0.3 M) and the studies revealed that PNP was the most difficult to be desorbed. Approximately 75% of PNP was recovered while 82% of PCP and 84% of TCP were recovered.

Le procédé de galvanisation à chaud se compose d’un recuit continu suivi d’une immersion de la bande d’acier dans un bain de zinc afin de lui conférer une protection contre la corrosion. Au cours de l’étape de recuit de recristallisation des nouveaux aciers, dits à « haute limite élastique », les éléments d’addition, tel que l’aluminium, ségrégent et diffusent en surface où ils forment des îlots voire des films superficiels qui, mal mouillés par le zinc liquide, nuisent à la qualité du produit final. Dans ce cadre, l’étude s’est attachée d’une part à caractériser l’oxydation sélective d’alliages binaires Fe-Al et d’autre part, dans le cas modèle de l’α-alumine (0001), à déterminer les effets de la terminaison de surface sur l’énergie d’adhésion du zinc, à l’aide d’une approche combinant simulations numériques ab initio (théorie de la fonctionnelle de la densité) et expériences sous ultra-vide (réflectivité UV-visible, photoémission et désorption thermique). A l’issu de recuits calqués sur les conditions industrielles les alliages binaires Fe-Al (1,5 et 8% pds.) présentent en surface une couche couvrante d’γ-alumine de plusieurs nanomètres d’épaisseur. Une entrée du flux de gaz focalisée sur l’échantillon aboutit à une croissance vermiculaire des grains d’alumine alors qu’un flux de gaz homogène engendre une croissance plus structurée qui montre que l’approche modèle Zn/α-alumine (0001) est pertinente.Les simulations numériques faites aux premiers stades du dépôt, ont montré que, le zinc interagit faiblement avec la surface stœchiométrique (1x1), ce qui confirme l’expérience. Expérience et calcul convergent sur la valeur de ≈ 0,5 eV de l’énergie d’adsorption. Par contre, un excès de charge de surface peut considérablement renforcer l’adsorption. Deux mécanismes ont été identifiés et décrits en terme de stabilité thermodynamique, en fonction des conditions environnementales (pression, température) : (i) une sous-stœchiométrie surfacique en Al, telle que présente sur la terminaison polaire, (ii) un excès de groupements hydroxyles de surfaces, issus de la dissociation de l’eau, opérationnel aussi bien sur la terminaison polaire que non-polaire de l’alumine. En parallèle avec l’expérience, la simulation montre que le zinc est capable d’interagir fortement avec la surface en en déplaçant l’hydrogène des groupements hydroxyles de surface. L’énergie d’adsorption du zinc ainsi adsorbé, évaluée à 7 eV par le calcul, est du même ordre que la valeur expérimentale de 3,5 eV. L’étude étendue à plusieurs métaux de transition a permis d’identifier le titane comme élément montrant l’interaction la plus forte avec l’alumine et qu’un enrichissement en titane de la surface d’alumine peut fortement améliorer l’adhésion du zinc. / The process of continuous hot galvanization consists in annealing and then diving a steel strip in a zinc bath to confer it a protection against corrosion. During the recrystallization annealing step of the so call “high elastic limit’ steels, the additional elements, such as aluminum, segregate and diffuse towards the surface and form oxide islands or superficial film which degrade the zinc adhesion and harm the final quality. This study attempted, on one hand to characterize the selective oxidation of binary alloys and, on the other hand, to improve adhesion at the zinc/α-Al2O3 (0001) interface taken as a test bed. The originality of the research program is to be based on both numerical ab initio simulation (density functional theory) and experiments (UV-vis reflectivity, photoemission, thermal desorption) to determine the parameters of greater relevance.After annealing based on industrial conditions, binary alloys (1.5%- 8% wt.) are totally covered by γ-alumina layer some nanometers in thickness. Gas flow focused on the sample leads to a ‘worm’ like growth of the alumina grains while an homogeneous flow gives rise to a well- structured growth which shows the relevance of the study of Zn/α-alumina (0001).The numerical simulations of the early stage of deposition show that, zinc interacts weakly on a stoichiometric surface (1x1) what is in agreement with experiments. Experiment and theory converge on 0.5 eV for adhesion energy. On the other hand, an excess of surface charge can considerably reinforce the adsorption. Two mechanisms were identified and described in terms of thermodynamics stability according to the environmental conditions (pressure, temperature): (i) electron deficiency present at polar termination, such as oxygen rich (ii) an excess of surface hydroxyls groups issued from water dissociation. Interestingly, this effect is operational on both polar and non-polar terminations. In parallel with experiments, calculation show zinc is able to spill over the hydroxyls groups and interact strongly with the surface. Adhesion energy is 7 eV which is in a good agreement with the 3.5 eV of experimental value. Extended over the 3d transition metals series, the calculations identify titanium as the element exposing the strongest interaction with alumina. By focusing on the adhesive characteristics at the Zn/alumina interfaces, calculations show that titanium enrichment can indeed improve considerably the adhesion.

abstract: Limited access to clean water due to natural or municipal disasters, drought, or contaminated wells is driving demand for point-of-use and humanitarian drinking water technologies. Atmospheric water capture (AWC) can provide water off the centralized grid by capturing water vapor in ambient air and condensing it to a liquid. The overarching goal of this dissertation was to define geographic and thermodynamic design boundary conditions for AWC and develop nanotechnology-enabled AWC technologies to produce clean drinking water. Widespread application of AWC is currently limited because water production, energy requirement, best technology, and water quality are not parameterized. I developed a geospatial climatic model for classical passive solar desiccant-driven AWC, where water vapor is adsorbed onto a desiccant bed at night, desorbed by solar heat during the day, and condensed. I concluded passive systems can capture 0.25–8 L/m2/day as a function of material properties and climate, and are limited because they only operate one adsorption-desorption-condensation cycle per day. I developed a thermodynamic model for large-scale AWC systems and concluded that the thermodynamic limit for energy to saturate and condense water vapor can vary up to 2-fold as a function of climate and mode of saturation. Thermodynamic and geospatial models indicate opportunity space to develop AWC technologies for arid regions where solar radiation is abundant. I synthesized photothermal desiccants by optimizing surface loading of carbon black nanoparticles on micron-sized silica gel desiccants (CB-SiO2). Surface temperature of CB-SiO2 increased to 60oC under solar radiation and water vapor desorption rate was 4-fold faster than bare silica. CB-SiO2 could operate >10 AWC cycles per day to produce 2.5 L/m2/day at 40% relative humidity, 3-fold more water than a conventional passive system. Models and bench-scale experiments were paired with pilot-scale experiments operating electrical desiccant and compressor dehumidifiers outdoors in a semi-arid climate to benchmark temporal water production, water quality and energy efficiency. Water quality varied temporally, e.g, dissolved organic carbon concentration was 3 – 12 mg/L in the summer and <1 mg/L in the winter. Collected water from desiccant systems met all Environmental Protection Agency standards, while compressor systems may require further purification for metals and turbidity. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2020

Thermal desorption (TD), a remediation method used to remove hydrocarbons from contaminated soils, may cause changes in soil properties that threaten soil function and plant productivity. The goal of this research is to better understand the effect that TD treatment has on soils intended for agricultural use. A series of soil phosphorus (P) sorption and desorption experiments were conducted on soils before and after TD treatment to determine P availability for plant uptake and risk for run-off. TD-treated soils retained more P, likely due to mineral transformations of Fe- and Al-oxides. In addition, a three-year field study using mixtures of topsoil (A), crude-contaminated soil (SP), and TD-treated soils (TDU) was conducted. Yields were significantly greater in plots that included A in the mixture compared to SP and TDU soils alone. TD-treated soils can be a replacement for topsoil, but the addition of topsoil will reduce the time to successful reclamation.