Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

According to the Texas Railroad Commission (TRC), ????over 250 billion gallons of produced water is taken out of Texas Soil every year, and more than 35% of this water is not currently fit to use.?? Therefore, it can be assumed that domestically and globally, the petroleum industries challenge has been to develop a high-tech and cost effective method to purify the large volumes of oilfield brines and produced water. Currently, most of the produced water requires several pre- and post- treatment methods to aide in reducing fouling of membranes, separation of components, increasing influent and effluent quality, and preventing unwanted work stoppage during the desalination process. As a result, the pre- and post- treatment conditioning of the produced water affects the economics and scale-up (i.e. residence times, absorption capacity, etc??) of the varying processes parameters. Therefore, this research focuses on developing an economic analysis and determining the adsorption capacity of an organoclay system to remove oil.

This thesis is concerned with a project to apply the method of pressure modulation radiometry to measurements of the temperature and water vapour distributions in the atmosphere of Mars. The technique has already been used successfully to measure temperature (and occasionally composition) in the atmospheres of Earth and Venus. Two pressure modulators, containing carbon dioxide and water vapour respectively, are used in the Pressure Modulator Infrared Radiometer (PMIRR), on the payload of Mars Observer, scheduled for launch in September 1992. The composition of the Martian atmosphere is almost pure CO2, so the emission lines are unusually broad, so that the mean pressure in the CO2 modulator has to be much larger than for previous modulators, thus increasing the power consumption. The limited power available in a Martian spacecraft requires that the power consumption of the pressure modulator and drive be minimized. As a result a high­efficiency drive circuit was designed and developed. Water vapour is of major importance to the Martian environment and there are several outstanding questions about its behaviour. Measurements using the pressure modulator technique for terrestrial water vapour measurements have had limited success, raising questions about its suitability for condensible, affinitive molecules. A new model of the thermodynamics of pressure modulators was developed to predict their mechanical and spectroscopic behaviour, and spectroscopic measurements of the pressure modulator cell transmission, with high spectral and temporal resolution, using a tunable diode laser spectrometer (TDLS), were performed. The measured transmission agrees well with the predictions of the model, indicating that pressure modulation radiometry can be applied to measurements of water vapour, giving confidence in the successful study of Martian climatology by the PMIRR instrument.

京都大学 / 0048 / 新制・論文博士 / 博士(工学) / 乙第12931号 / 論工博第4124号 / 新制||工||1626(附属図書館) / 32141 / (主査)教授 北川 進, 教授 杉野目 道紀, 教授 濵地 格 / 学位規則第4条第2項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

No description available.

Filmes de água cobrem a maior parte das superfícies em condições ambientes. O estudo dessas interfaces é crucial em biologia e em ciência dos materiais. No entanto, o completo entendimento da adsorção da água e de suas complexas redes de ligações de hidrogênio ainda não foi alcançado. Somente recentemente possuímos técnicas com a sensibilidade e seletividade para estudar estas superfícies até a última camada atômica. A espectroscopia por geração de soma de frequências (SFG) é uma técnica óptica não linear que fornece o espectro vibracional de moléculas em interfaces, sem contribuição do volume do material. A técnica SFG foi utilizada para estudar a estrutura interfacial das moléculas de água estrutural na face livre (010) do cristal natural gipsita (CaSO4 2H2O) e a adsorção de água na mesma à temperatura ambiente. Os espectros SFG na face livre (010), em atmosfera inerte, apresentaram um arranjo com anisotropia azimutal das moléculas de água estrutural com a presença de grupos OH ligados à superfície e grupos OH livre sem formar ligação de hidrogênio, apontando para fora da superfície. O arranjo anisotrópico das moléculas na face (010) é diferente daquele para as moléculas de água no volume do cristal. A adsorção de água foi estudada em equilíbrio com vapor de água em vários valores de umidade relativa. A água adsorvida na gipsita (010) também apresenta um arranjo anisotrópico, porém, diferentemente da água estrutural na superfície livre do cristal, esta apresenta um menor grau de ordenamento e suprime consideravelmente a presença de grupos OH livre. Os resultados experimentais são analisados em conjunto com simulações por dinâmica molecular ab initio realizadas por colaboradores. As simulações apresentaram boa concordância qualitativa e quantitativa com os resultados experimentais, permitindo fazer a atribuição dos espectros vibracionais experimentais, e fornecendo informações difíceis de se obter dos experimentos, como a distribuição orientacional das moléculas de água na interface e sua dinâmica de difusão espacial. / Water films cover most of surfaces under ambient conditions. The study of these interfaces is crucial in biology and materials science. However, a complete understanding of water adsorption and its complex hydrogen bonding networks has not yet been achieved. Only recently we have techniques with the sensitivity and selectivity to study these surfaces to the last atomic layer. Sum-frequency generation (SFG) is a non-linear optical technique that provides the vibrational spectrum of molecules at interfaces, without contribution from the bulk. This technique was used to study the interfacial structure of neat (010) face of Gypsum (CaSO4 2H2O) single crystals and water adsorption on the (010) face at room temperature. The SFG spectra for the neat Gypsum face (010), in inert atmosphere, presented azimuthally anisotropy arrangement of the structural water molecules with the presence of OH groups bound to the surface and free OH groups pointing out of the surface. The arrangement of water molecules on the face (010) is anisotropic but different from that of the water molecules in the bulk crystal. Water adsorption was studied in equilibrium with water vapor at several values of relative humidity. The adsorbed water also exhibited an anisotropic arrangement, however, unlike the structural water, it presents a lower ordering and the free OH groups are strongly suppressed. The experimental results are analyzed together with ab initio molecular dynamics simulations performed by collaborators. The simulations presented good qualitative and quantitative agreement with the experimental results, elucidating the assignment of the experimental vibrational spectra and yielding information that would be difficult to get from the experiments, such as the orientational distribution of interfacial water molecules and their spatial diffusion dynamics.

Nesse trabalho foi proposto investigar a estabilidade de fases do sistema zircônia-escândia (ScSZ) por meio do estudo termodinâmico de nanopartículas, na faixa de 0 a 20% em mol de Sc2O3, e a partir da introdução de um segundo aditivo (Dy2O3 e Nb2O5) ao ZrO2 contendo 10% em mol de Sc2O3 (10ScSZ). A estabilidade de fases do ScSZ foi avaliada com base em dados termodinâmicos determinados pelas técnicas de microcalorimetria de adsorção de água e calorimetria de dissolução à alta temperatura. As soluções sólidas foram sintetizadas pelo método de coprecipitação de hidróxidos. Dados termodinâmicos foram determinados para as formas polimórficas encontradas (monoclínica, tetragonal, cúbica, romboédrica β e γ) por difração de raios X no ScSZ. Esse trabalho resultou no diagrama de fases em nanoescala de tamanho de partícula-composição. Os efeitos produzidos pela introdução de aditivos na matriz de 10ScSZ foram investigados visando obter a possível estabilização da estrutura cúbica (c) e a supressão da transformação de fase c-β, característica do sistema binário. As composições foram sintetizadas por coprecipitação de hidróxidos e por reações em estado sólido para fins comparativos. Os materiais foram sinterizados convencionalmente e por sinterização assistida por campo elétrico. A estabilização completa da fase cúbica ocorreu a partir de teores molares de 1% de Dy2O3 e 0,5% de Nb2O5. O menor teor de Nb2O5 necessário para a estabilização da fase foi atribuído à provável formação da fase líquida durante a sinterização e ao menor tamanho do íon Nb5+. Os resultados de difratometria de raios X em alta temperatura e análise térmica mostraram que houve supressão da transição c-β. As amostras contendo 0,5% mol de Nb2O5 apresentaram valores de condutividade iônica similares aos do 10ScSZ sem aditivos em uma ampla faixa de temperatura com elevada estabilidade em um período de 170 h a 600 °C. / In this work, the phase stability of scandia-zirconia (ScSZ) system was investigated by the thermodynamic study of nanoparticles, within the range of 0 to 20 mol% Sc2O3, and by codoping of ZrO2-10 mol% Sc2O3 (10ScSZ) with Dy2O3 and Nb2O5. The phase stability of ScSZ was evaluated based on thermodynamic data collected by water adsorption microcalorimetry and high temperature oxide melt solution. Nanostructured zirconia-scandia solid solutions were synthesized by coprecipitaion method. Thermodynamic data were determined for ScSZ polymorphs (monoclinic, tetragonal, cubic, rhombohedral β and γ) found by X-ray diffraction. This systemic work resulted in an unprecedented phase diagram at the nanoscale of particle size-composition. The effects of additives on 10ScSZ were investigated aiming to stabilize the cubic (c) structure at room temperature and to suppress the characteristic cubic-rhombohedral β phase transformation. Compositions were prepared by coprecipitation and solid state reaction. Materials were sintered by conventional and spark plasma sintering. Full stabilization of the cubic phase was attained by 1 mol% Dy2O3 and 0.5 mol% Nb2O5 additions. The smallest Nb2O5 content required for cubic phase stabilization was attributed to liquid phase formation during sintering and to small ionic radius of Nb5+. Results of high temperature X-ray diffraction and thermal analysis show suppression of the c-β transformation. Samples containing 0.5 mol% Nb2O5 show total ionic conductivity similar to 10ScSZ without additives within a broad temperature range with high stability during 170 h at 600 °C.

Nesse trabalho foi proposto investigar a estabilidade de fases do sistema zircônia-escândia (ScSZ) por meio do estudo termodinâmico de nanopartículas, na faixa de 0 a 20% em mol de Sc2O3, e a partir da introdução de um segundo aditivo (Dy2O3 e Nb2O5) ao ZrO2 contendo 10% em mol de Sc2O3 (10ScSZ). A estabilidade de fases do ScSZ foi avaliada com base em dados termodinâmicos determinados pelas técnicas de microcalorimetria de adsorção de água e calorimetria de dissolução à alta temperatura. As soluções sólidas foram sintetizadas pelo método de coprecipitação de hidróxidos. Dados termodinâmicos foram determinados para as formas polimórficas encontradas (monoclínica, tetragonal, cúbica, romboédrica β e γ) por difração de raios X no ScSZ. Esse trabalho resultou no diagrama de fases em nanoescala de tamanho de partícula-composição. Os efeitos produzidos pela introdução de aditivos na matriz de 10ScSZ foram investigados visando obter a possível estabilização da estrutura cúbica (c) e a supressão da transformação de fase c-β, característica do sistema binário. As composições foram sintetizadas por coprecipitação de hidróxidos e por reações em estado sólido para fins comparativos. Os materiais foram sinterizados convencionalmente e por sinterização assistida por campo elétrico. A estabilização completa da fase cúbica ocorreu a partir de teores molares de 1% de Dy2O3 e 0,5% de Nb2O5. O menor teor de Nb2O5 necessário para a estabilização da fase foi atribuído à provável formação da fase líquida durante a sinterização e ao menor tamanho do íon Nb5+. Os resultados de difratometria de raios X em alta temperatura e análise térmica mostraram que houve supressão da transição c-β. As amostras contendo 0,5% mol de Nb2O5 apresentaram valores de condutividade iônica similares aos do 10ScSZ sem aditivos em uma ampla faixa de temperatura com elevada estabilidade em um período de 170 h a 600 °C. / In this work, the phase stability of scandia-zirconia (ScSZ) system was investigated by the thermodynamic study of nanoparticles, within the range of 0 to 20 mol% Sc2O3, and by codoping of ZrO2-10 mol% Sc2O3 (10ScSZ) with Dy2O3 and Nb2O5. The phase stability of ScSZ was evaluated based on thermodynamic data collected by water adsorption microcalorimetry and high temperature oxide melt solution. Nanostructured zirconia-scandia solid solutions were synthesized by coprecipitaion method. Thermodynamic data were determined for ScSZ polymorphs (monoclinic, tetragonal, cubic, rhombohedral β and γ) found by X-ray diffraction. This systemic work resulted in an unprecedented phase diagram at the nanoscale of particle size-composition. The effects of additives on 10ScSZ were investigated aiming to stabilize the cubic (c) structure at room temperature and to suppress the characteristic cubic-rhombohedral β phase transformation. Compositions were prepared by coprecipitation and solid state reaction. Materials were sintered by conventional and spark plasma sintering. Full stabilization of the cubic phase was attained by 1 mol% Dy2O3 and 0.5 mol% Nb2O5 additions. The smallest Nb2O5 content required for cubic phase stabilization was attributed to liquid phase formation during sintering and to small ionic radius of Nb5+. Results of high temperature X-ray diffraction and thermal analysis show suppression of the c-β transformation. Samples containing 0.5 mol% Nb2O5 show total ionic conductivity similar to 10ScSZ without additives within a broad temperature range with high stability during 170 h at 600 °C.

Understanding the structure and dynamics of molecularly thin films or the state of water confined to nanoscale dimensions is an active field of research and has wide applications in areas ranging from biology to geology. The issues concern fundamental aspects related to the manner in which a substrate influences the organization of water, origin of forces present when water is confined to nanoscale dimensions, and the influence on the structure and dynamics of water adjacent to a surface. The focus of this thesis lies in examining the thermodynamics and transport properties of interfacial and confined water. As a prelude to studying the structure of water confined between two mica surfaces, we first investigated the structuring of water adjacent to a single mica surface using grand canonical Monte Carlo (GCMC) simulations. The adsorption isotherm reveals three distinct stages as the relative vapor pressure in increased. The derived film thickness, isotherm shape, and heats of adsorption are in excellent agreement with recent experimental data. Our study does not support the 2D ice hypothesis and indicates that beyond the first adsorbed layer water is liquid-like. The characteristics of water confined to nanometer dimensions between two hydrophilic surfaces are investigated to assess the influence of chemical functionality of the hydrophilic surface on the structure of confined water. Our study shows that hydration of potassium ions on the mica surface has a strong influence on the water structure and solvation force response of confined water. In contrast to the disrupted hydrogen bond network observed for water confined between mica surfaces, water between silica surfaces is able to retain its hydrogen bond network displaying bulk-like structural features down to surface separations as small as 0.45 nm. An oscillatory solvation force response is observed only for water confined between silica surfaces. We evaluate and contrast the water density, dipole moment distributions, pair correlation functions and the solvation forces as a function of the surface separation. Recent experimental studies have shown that even for subnanometer confinement, the shear viscosity of water between mica surfaces is only three times larger than the free water viscosity. The dynamics of confined water between mica surfaces is evaluated using molecular dynamics simulations. Our analysis shows that the residence time for water in the contact layer is about two orders of magnitude larger than water in the central bulk-like regions between the surfaces. The K+ ions have a strong influence on the dynamics of confined water, leading to a decoupling in the translation and orientational motions. Our analysis also shows the presence of orientational jump dynamics in the contact layer near the mica surface. We also investigate the influence of confinement on the hydration characteristics of NaCl solutions both as a function of the salt concentration and the surface separation, H between graphite surfaces. A hydration limit is defined as the concentration at which a rapid drop in the hydration number is observed with increasing salt concentration. Despite a high degree of confinement, ions are able to form a quasi two-dimensional hydration shell between the two surfaces. The hydration number, reduces to about 4.15 at a pore width of H =8 A, when compared with the bulk hydration number of 6.25. In many practical situations, surfaces that are separated by an intervening fluid can be dissimilar giving rise to the so called Janus interface. In order to probe the fluid structure in such systems, we studied non-polar fluids confined between two asymmetric surfaces. By varying the degree of asymmetry between the two surfaces a wide variety of adsorption situations are examined using GCMC simulations and a mean field lattice model. The degree of asymmetry is found to influence the presence of frozen phases and can also support co-existing liquid and solid phases.

Theoretical methods can be used to describe surface chemical reactions in detail and with sufficient accuracy. Advances, especially in density functional theory (DFT) method, enable to compare computational results with experiments. Quantum chemical calculations employing ONIOM DFT/B3LYP/6-31G**-MM/UFF cluster method provided in Gaussian 03 are conducted to investigate water adsorption on rutile (110), and water and ammonia adsorption on anatase (001) surfaces of titanium dioxide. Water and ammonia adsorption on anatase (001) surface is studied by also performing PW:DFT-GGA-PW91 periodic DFT method by using VASP code and the results are compared with the results of ONIOM method. The results obtained by means of ONIOM method indicate that dissociative water adsorption on rutile (110) surface is not favorable due to high activation barrier, whereas on anatase (001) surface, it is favorable since molecular and dissociative water adsorption energies are calculated to be -23.9 kcal/mol and -58.12 kcal/mol. Moreover, on anatase (001) surface, dissociative ammonia adsorption is found energetically more favorable than molecular one (-37.17 kcal/mol vs. -23.28 kcal/mol). Thermodynamic functions at specific experimental temperatures for water and ammonia adsorption reactions on anatase (001) surface are also evaluated. The results obtained using periodic DFT method concerning water adsorption on anatase (001) surface indicate that dissociative adsorption is more favorable than molecular one (-32.28 kcal/mol vs. -14.62 kcal/mol) as in ONIOM method. On the same surface molecular ammonia adsorption energy is computed as -25.44 kcal/mol. The vibration frequencies are also computed for optimized geometries of adsorbed molecules. Finally, computed adsorption energy and vibration frequency values are found comparable with the values reported in literature.