京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22068号 / 工博第4649号 / 新制||工||1725(附属図書館) / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 邑瀬 邦明, 教授 宇田 哲也, 教授 杉村 博之 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Now when the interest is increasing to reach a sustainable infrastructure, one possibility SCA is experimenting with is the possibility to produce renewable hydrocarbons from black liquor which can be extracted from a Kraft process. However, when extracting the black liquor, a lot of sodium-based compounds are removed from the recovery process and when hydrocarbons are produced in SCA’s biorefinery, these compounds are caught in an aqueous solution. The aqueous solution is received at 50°C, and the sodium-based compounds are mainly sodium sulfate and sodium carbonate, where the solution do also contain organic compounds and a solvent that is used in the biorefinery.  This thesis focused on building a concept to extract sodium sulfate from the aqueous solution. The thesis did also include if any additional preparatory work needs to be done to the solution before extracting sodium sulfate. Finally, a flow chart that maps the energy needed for the process was created.  The method that was used was crystallisation by cooling the solution. By cooling the solution, sodium sulfates solubility decreases which will result in that sodium sulfate falls out of the solution as crystals. It was determined that the solvent that the solution contains should be extracted if the solvents boiling temperature is below 100°C. Further, by cooling the solution under stirring to 15°C with a residence time of 3 hours, unwanted compounds can be extracted. By later cooling the solution under stirring to 5°C with a residence time of 1 hour, it gave sodium sulfate decahydrate (Na2SO4·10H2O) with small amounts of organic compounds. By removing the water, the dry product reached a purity of 94wt% sodium sulfate with a yield of 12% (mass of dry product/mass of aqueous solution). This result reached the specific objectives that were set at the start of this thesis, which was to reach a purity of 90wt% sodium sulfate with a yield of 5%.  The energy intensity for evaporating the solvent is expected to be high. It highly depends on which solvent is used. However, this process can use the lowest quality of steam that is available from the pulp mill. It is expected that the cooling will require high amounts of cooling water and a high investment cost for the heat exchanger. Yet, this is a vital part of the process to reduce the need for coolers which is powered by electricity. / Nu när intresset ökar, för att nå en hållbar infrastruktur, så experimenterat SCA med möjligheten att producera förnybara kolväten från svartlut som kan extraheras från en sulfatprocess. Vid extrahering av svartluten tas dock mycket natriumbaserade föreningar bort från återvinningsprocessen och när kolväten produceras i SCA:s bioraffinaderi fastnar dessa föreningar i en vattenlösning. Den lösningen tas emot vid 50°C och de natriumbaserade föreningarna är huvudsakligen natriumsulfat och natriumkarbonat, där lösningen också innehåller organiska föreningar och ett lösningsmedel som används i bioraffinaderiet. Denna avhandling fokuserade på att bygga ett koncept för att extrahera natriumsulfat från vattenlösningen. Avhandlingen omfattade också om ytterligare förberedande arbete måste göras av lösningen innan man extraherar natriumsulfat. Slutligen skapades ett flödesschema som kartlägger den energi som behövs för processen. Metoden som bestämde sig för att användas var kristallisering genom kylning av lösningen. Genom att kyla lösningen minskar lösligheten av natriumsulfater vilket leder till att natriumsulfat faller ut ur lösningen som kristaller. Det bestämdes att lösningsmedlet som lösningen innehåller skulle extraheras om lösningsmedlets koktemperatur är under 100°C. Vidare, genom att kyla lösningen under omrörning till 15°C med en uppehållstid på 3 timmar, kan oönskade ämnen extraheras. Genom att senare kyla lösningen under omrörning till 5°C med en uppehållstid på 1 timme gav natriumsulfatdekahydrat (Na2SO4·10H2O) med små mängder organiska föreningar. Genom att avlägsna vattnet nådde den torra produkten en renhet av 94 vikt% natriumsulfat med ett utbyte av 12% (massa torr produkt/massa vattenlösning). Detta resultat nådde de specifika mål som sattes i början av denna avhandling, vilket var att nå en renhet av 90 vikt% natriumsulfat med ett utbyte på 5%. Energiintensiteten för att förånga lösningsmedlet förväntas vara hög. Det beror mycket på vilket lösningsmedel som används. Denna process kan dock använda den lägsta ångkvaliteten som finns tillgänglig från massafabriken. Det förväntas att kylningen kommer att kräva stora mängder kylvatten och höga investeringskostnader för värmeväxlaren. Ändå är detta en viktig del av processen för att minska behovet av kylare som drivs av elektricitet.

No / The Sikhote-Alin (SA) meteorite is an example of a type IIAB octahedrite iron meteorite with ca. 0.5 wt% phosphorus (P) content principally in the form of the siderophilic mineral schreibersite (Fe,Ni)(3)P. Meteoritic in-fall to the early Earth would have added significantly to the inventory of such siderophilic P. Subsequent anaerobic corrosion in the presence of a suitable electrolyte would produce P in a form different to that normally found within endogenous geochemistry which could then be released into the environment. One environment of specific interest includes the low pH conditions found in fumaroles or volcanically heated geothermal waters in which anodic oxidation of Fe metal to ferrous (Fe2+) and ferric (Fe3+) would be coupled with cathodic reduction of a suitable electron acceptor. In the absence of aerobic dioxygen (E-o = +1.229 V), the proton would provide an effective final electron acceptor, being converted to dihydrogen gas (E-o = 0 V). Here we explore the hydrothermal modification of sectioned samples of the Sikhote-Alin meteorite in which siderophilic P-phases are exposed. We report on both, (i) simulated volcanic conditions using low pH distilled water and (ii) geothermally heated sub-glacial fluids from the northern Kverkfjoll volcanic region of the Icelandic Vatnajokull glacier. A combination of X-ray photoelectron spectroscopy (XPS) and electrochemical measurements using the scanning Kelvin probe (SKP) method reveals that schreibersite inclusions are significantly less susceptible to anodic oxidation than their surrounding Fe-Ni matrix, being some 550 mV nobler than matrix material. This results in preferential corrosion of the matrix at the matrix-inclusion boundary as confirmed using topological mapping via infinite focus microscopy and chemical mapping through Raman spectroscopy. The significance of these observations from a chemical perspective is that electrochemically noble inclusions such as schreibersite are likely to have been released into the geological environment through an undermining corrosion of the surrounding matrix, thus affording localised sources of available water-soluble, chemically reactive P in the form of H-phosphite [H2PO3-, Pi(III) as determined by P-31 NMR spectroscopy]. This compound has been shown to have considerable prebiotic chemical potential as a source of condensed P-oxyacids. Here we demonstrate that Pi(III) resulting from the hydrothermal modification of Sikhote- Alin by sub-glacial geothermal fluids can be readily dehydrated into the condensed P-oxyacid pyrophosphite [H2P2O52-, PPi(III)] by dry-heating under mild (85 degrees C) conditions. The potential significance of this latter condensed P-compound for prebiotic chemistry is discussed in the light of its modified chemical properties compared to pyrophosphate [H2P2O72-, PPi(V)].

Traditional excess Gibbs energy models in terms of temperature, pressure, and concentration become progressively less effective in describing the thermodynamics of aqueous solutions at temperatures above 300 ¢ªC, and are totally inadequate in the critical region of water. This deficiency is due to the strong ion association and the large property fluctuations (such as density) with small variations in pressure, temperature, and solute concentration around the critical point of water. In this work, a speciation-based model has been developed to describe the thermodynamic properties of aqueous sodium chloride solutions in the critical region of water. The anomalous fluctuation problem is avoided by adopting a residual Helmholtz energy approach in terms of temperature, density, and solute concentration. Partial ion dissociation is accounted for by including an isochoric equilibrium constant equation and a mean spherical approximation in the present model. The present model includes such classical interactions or effects as hard-sphere interactions, dipole-dipole interactions, ion dissociation effects, long-range ion-ion interactions, and a non-classical perturbation term. The related parameters that account for these effects were regressed to fit the measured values in the critical region of water. Densities, compressibility factors, apparent molar volumes, heats of dilution, and apparent isobaric molar heat capacities were used to test the validity of the model. The predicted values in this work agree well with the literature data over a wide range of temperatures (350 to 400 ¢ªC), pressures (17.5 to 40 MPa), and sodium chloride concentrations (0 to 5 mol/kg). Comparisons with other models are also included in this work. This model can be used to predict speciation, solute dissociation reaction, and many other comprehensive properties in aqueous sodium chloride solutions at near-critical conditions.

No description available.

The purpose of the research was to design, build, test, and recommend a process to economically separate CO from a gas mixture of CO, CO2, and O2. The general method considered in this research to accomplish the separation was liquid absorption in a packed column. Several experiments were performed to identify the best process solution to use in a prototype. The experiments, based on the COSORB process, consisted of CuCl mixed with a complexing agent (metal tri-chloride) and a solvent (metal tetra-chloride, toluene, ethanol, etc.). The best method consisted of an aqueous solution of CuCl and MgCl2, which has previously been used for CO absorption experiments reported in the literature. The absorption takes place at elevated pressure (30 psig) and ambient temperature, and the stripping occurs at approximately 75 ºC. Using the apparatus at approximate design conditions, the highest removal of CO was 88% with a product composition of 48%. The highest product composition achieved was 84%; in this case CO removal was 66%. Product composition was low because a significant amount of CO2 physically absorbed into solution (which also decreased the pH of the solution to about 4, according to calculation). The removal of CO should increase with a taller column and higher liquid flow through the column; however, this might decrease the product composition. Advantages of this process are that the raw materials used are relatively cheap, heating and cooling requirements are lower than similar processes, and operation is relatively simple.

Yes / Small-angle neutron scattering (SANS) and neutron spin-echo (NSE) have been used to investigate the temperature-dependent solution behaviour of highly-branched poly(N-isopropylacrylamide) (HB-PNIPAM). SANS experiments have shown that water is a good solvent for both HB-PNIPAM and a linear PNIPAM control at low temperatures where the small angle scattering is described by a single correlation length model. Increasing the temperature leads to a gradual collapse of HB-PNIPAM until above the lower critical solution temperature (LCST), at which point aggregation occurs, forming disperse spherical particles of up to 60 nm in diameter, independent of the degree of branching. However, SANS from linear PNIPAM above the LCST is described by a model that combines particulate structure and a contribution from solvated chains. NSE was used to study the internal and translational solution dynamics of HB-PNIPAM chains below the LCST. Internal HB-PNIPAM dynamics is described well by the Rouse model for non-entangled chains.

Résumé : La pollution de l'environnement est devenue un problème mondial majeur. Le développement rapide des industries de procédés conduit à une augmentation constante des quantités d'eaux usées et des liqueurs contaminées rejetées. Les acides carboxyliques représentent une part importante de la charge organique des polluants dans les eaux usées et dans les solutions aqueuses industrielles. Une technologie efficace et respectueuse de l'environnement est donc requise pour réduire les effets négatifs de l'industrialisation sur l'environnement et pour éliminer les polluants des eaux usées et des liqueurs industrielles contaminées. Le plasma thermique submergé à courant continu (CC) est l'une des technologies proposées pour éliminer les contaminants des liquides et des solutions. Le réacteur au plasma thermique submergé à courant continu est un nouveau réacteur dans lequel le contact direct entre le plasma et la solution est établi. Une caractéristique importante du plasma thermique type CC est le gaz de plasma. Selon le type du gaz plasmagène, les plasmas thermiques CC présentent différents taux de décomposition, d’espèces réactives, d’enthalpies, de conductivités thermiques, et de temps de vie des électrodes. Parmi les différentes torches des plasmas thermiques CC, la torche à plasma thermique à mélange gazeux à base de CO[indice inférieur 2], récemment inventée, présente une amélioration très significative de la performance, c'est-à-dire une enthalpie plasmatique et une conductivité thermique élevées par rapport à celles des gaz de plasma concurrents. Une approche principalement expérimentale a permis d’étudier la faisabilité et le mécanisme de décomposition de l'acide carboxylique à haut poids moléculaire dans des solutions via les différents plasmas thermique submergés à CC. L'acide sébacique, un acide carboxylique à haut poids moléculaire a été choisi comme représentant de contaminant de type organique dans la liqueur Bayer. Deux différentes torches de plasma, incluant la torche à plasma oxygène et air ainsi que la torche à plasma CO[indice inférieur 2]/CH[indice inférieur 4] nouvellement conçues ont été utilisées. L'effet des différentes conditions de fonctionnement en incluant le temps de traitement, le pH initial de la solution, et la pression du réacteur, ainsi que le rôle des agents oxydants tels que le H[indice inférieur 2]O[indice inférieur 2], ont été étudiés sur la décomposition de l'acide sébacique. Pour identifier le rôle des différents gaz de plasma et des conditions opérationnelles sur le mécanisme de décomposition et sur les produits intermédiaires, une caractérisation qualitative et quantitative a été réalisée sur les solutions traitées avec la méthode de chromatographie ionique couplée à la spectrométrie de masse (IC/MS). L'effet thermochimique des gaz de plasma sur la décomposition de l’acide sébacique et sur les produits intermédiaires a également été étudié. À travers les différents essais réalisés dans cette étude, il a été montré pour la première fois que la décomposition de l'acide carboxylique de poids moléculaire élevé est réalisable avec le plasma thermique submergé en utilisant des gaz de plasmas différents. Le taux de décomposition d'acide sébacique lors de l’utilisation d’un plasma thermique à oxygène en milieu basique est plus élevé par rapport aux autres plasmas thermiques (air, et CO[indice inférieur 2]/CH[indice inférieur 4]) en mode submergé. Il a été constaté que cela est dû principalement à sa forte concentration en espèces oxydantes telles que l’ozone. Il a été observé que la décomposition de l'acide sébacique en milieu basique par l’utilisation de plasma d’oxygène et de plasma à air se produit par un mécanisme d'oxydation consécutif jusqu'à la production finale d'acides di-carboxyliques de plus faibles poids moléculaires et de CO[indice inférieur 2] (dissous dans la solution sous la forme de carbone inorganique). Il a été trouvé aussi pour la première fois que le plasma thermique submergé CO[indice inférieur 2]/CH[indice inférieur 4], peut décomposer l'acide carboxylique de poids moléculaire élevé sur la base d’un mécanisme séquentiel de photo-oxydation en raison de sa forte intensité de rayonnement ultraviolet. Le plasma de CO[indice inférieur 2]/CH[indice inférieur 4] a montré une vitesse de décomposition supérieure dans le milieu neutre. Par contre, en milieu basique, le plasma d'oxygène et le plasma d'air ont montré une vitesse de décomposition plus élevée. Il a également été montré que l'ajout d'H[indice inférieur 2]O[indice inférieur 2] en milieu basique a augmenté la vitesse de décomposition de l'acide sébacique avec le plasma CO[indice inférieur 2]/CH[indice inférieur 4] jusqu’à la même vitesse de décomposition que le plasma d'oxygène dû à une plus grande intensité de rayonnement UV du plasma de CO[indice inférieur 2] en comparaison avec celle du plasma d'oxygène. Dans une perspective plus générale, à travers différentes expériences, il a été montré que le plasma de CO[indice inférieur 2]/CH[indice inférieur 4] peut offrir une grande vitesse de décomposition des acides carboxyliques de poids moléculaire élevés dans un milieu acide et neutre, et également en milieu basique en présence de peroxyde d'hydrogène. Cela permettra le traitement des contaminants dans une grande variété de conditions de solution à l'aide de plasma du gaz CO[indice inférieur 2]. Les résultats de cette thèse aident à mieux comprendre la décomposition des contaminants organiques à hauts poids moléculaires dans les solutions utilisant les plasmas thermiques submergés. De plus, ces résultats proposent une application potentielle pour la torche à plasma de CO[indice inférieur 2] pour le traitement des eaux usées. // Abstract : Environmental pollution has become a major global problem. Rapid development of process industries leads to a constant increase in amounts of wastewater and contaminated industrial process liquors. Carboxylic acids represent a significant portion of the organic load of pollutant in wastewater and industrial aqueous solutions. An effective and environmentally friendly technology is therefore required to reduce the negative effects of industrialization on the environment and subsequently remove pollutants from wastewater and contaminated industrial liquors. DC (Direct Current) submerged thermal plasma is one of the proposed technologies for removing contaminants from liquids and solutions. DC submerged thermal plasma reactor is a novel reactor in which the direct contact between plasma and solution is established. An important characteristic of typical DC thermal plasma is the plasma gas. Depending on the type of plasma gas, DC thermal plasmas present different decomposition rates, reactive species, enthalpy, thermal conductivity, and electrode life time. Among different DC thermal plasma torches, the recently invented CO[subscript 2]-based gas mixture thermal plasma torch exhibits a very significant performance improvement, i.e. high plasma enthalpy and high thermal conductivity in comparison with competing plasma gases. In this study, by a mainly experimental approach, the feasibility and decomposition mechanism of high molecular weight carboxylic acid in solution via different DC submerged thermal plasmas has been investigated. Sebacic acid, a high molecular weight carboxylic acid, was selected as a representative of a typical organic contaminant in Bayer liquor. Two different DC plasma torches have been used including oxygen DC plasma torch and the newly designed CO[subscript 2]/CH[subscript 4] plasma torch. The effect of different operational conditions including treatment time, initial solution pH, and the reactor pressure as well as the role of oxidizing agents such as H[subscript 2]O[subscript 2], were investigated on the decomposition of sebacic acid. To identify the role of different plasma gases and operational conditions on the decomposition mechanism and its intermediate products, qualitative and quantitative characterization was done on the treated solutions with IC/MS (Ion Chromatography/Mass Spectrometry) method. The thermochemical effect of the plasma gases on the decomposition of sebacic acid and its intermediate products was also investigated. Through different experiments, it was shown for the first time that decomposition of high molecular weight carboxylic acid is feasible with submerged thermal plasma by using different plasma gases. The decomposition rate of sebacic acid by using oxygen thermal plasma in basic medium was higher compared with other thermal plasmas (air, and CO[subscript 2]/CH[subscript 4]) in submerged mode. It was found that the higher decomposition rate with oxygen plasma is mostly due to its high concentration of oxidant species such as ozone. The decomposition of sebacic acid in basic medium with oxygen and air plasma was revealed to occur with a consecutive oxidation mechanism up to the final production of the lowest molecular weight di-carboxylic acids and CO[subscript 2] gas (dissolved in solution in the form of inorganic carbon). It was found for the first time that the CO[subscript 2]/CH[subscript 4] submerged thermal plasma can decompose well high molecular weight carboxylic acid based on a sequential photo-oxidation mechanism due to its high ultraviolet (UV) radiation intensity. The CO[subscript 2]/CH[subscript 4] plasma showed higher decomposition rate in neutral medium, however oxygen and air plasma showed higher increased the sebacic acid decomposition rate with the CO[subscript 2]/CH[subscript 4] plasma up to the same decomposition rate of the oxygen plasma due to higher UV radiation intensity of the CO[subscript 2] plasma than that of the oxygen plasma. In a more general perspective, through different experiments, it was shown that CO[subscript 2]/CH[subscript 4] plasma can offer high decomposition rate for high molecular weight carboxylic acids in acidic and neutral medium and also in basic medium in the presence of hydrogen peroxide. This will allow using plasma for treatment of contaminants in a wide variety of solution conditions by using CO[subscript 2] gas. The findings of this thesis therefore will shed light on the decomposition of large organic contaminants in solutions with submerged thermal plasmas. Also, it provides a potential application for CO[subscript 2] plasma torch in wastewater treatment.

Mixed association of calix[4]resorcinarene with ethyl sulfonate groups on the lower rim and dimethylaminomethyl groups on the upper rim (CR) and cationic surfactant 4-aza-1-hexadecyl-azoniabicyclo[2.2.2]octane bromide (DABCO-16) is studied by methods of tensiometry, conductometry, potentiometry and NMR spectroscopy at fixed CR concentration and varied surfactant concentration. Beyond ca. 0.4 mM of DABCO-16, mixed aggregates enriched by CR are proved to be formed due to electrostatic forces, while beyond ca. 5 mM, aggregates enriched by surfactant occur due to the hydrophobic effect. Spectrophotometry monitoring of the solubilization of a hydrophobic dye, Orange OT, demonstrated that only the second type of mixed aggregate enriched by DABCO-16 is capable of binding the organic probe, while the mixed system where the surfactant is a minor component shows no binding capacity towards Orange OT. This finding can be used for the design of nanocontainers with controllable binding/release properties. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Neste trabalho, foi investigado o efeito do tamanho do abrasivo e do pH do meio na resistência ao desgaste abrasivo do aço H-13 com matriz martensítica e do aço Hadfield com matriz austenítica. Ensaios de abrasão foram realizados utilizando o equipamento roda de borracha a úmido, variando o tamanho do abrasivo entre 0,15 e 2,40 mm e o pH do meio entre 5,5 e 12,8. As microestruturas dos materiais estudados foram analisadas utilizando microscopia óptica, as superfícies de desgaste e as partículas de desgaste foram analisadas em microscópio eletrônico de varredura. A macrodureza e a microdureza, antes e após os ensaios, foram obtidas utilizando durômetro Vickers. A topografia da região central da superfície de desgaste foi obtida utilizando Perfilometria 3D, visando obter valores de profundidade de penetração do abrasivo. Os resultados mostraram que o aço Hadfield é mais resistente do que o aço H-13 em todos os valores de pH e tamanhos de abrasivo utilizados. Para os dois materiais, a perda de massa aumenta linearmente até um tamanho crítico de abrasivo (TCA) e, após este, a mesma continua a aumentar, mas com uma intensidade menor. Para os dois materiais e para todos os tamanhos de abrasivo, o aumento do pH do meio resultou em menores perdas de massa, sendo este efeito maior para os dois menores tamanhos de abrasivo. Para maiores valores de pH, foram observadas menores profundidades de penetração do abrasivo. A microdureza da superfície de desgaste do aço H-13 sofreu um pequeno aumento com o aumento do tamanho do abrasivo enquanto que para o aço Hadfield esse aumento foi mais intenso. A análise das partículas de desgaste mostraram que, para todas as condições ensaiadas, os debris do aço H-13 tinham duas morfologias, contínuas e descontínuas enquanto que os cavacos do aço Hadfield foram sempre descontínuos. Para os dois materiais, foram observados dois micromecanismos de desgaste, sendo eles microcorte e microsulcamento. Por fim, os resultados apresentados neste trabalho sugerem que a análise de desempenho do aço Hadfield em serviço deve considerar o pH do meio bem como a granulometria do abrasivo em contato. / In this work, the effects of abrasive particle size and pH value of the aqueous solution on abrasive wear resistance of the H-13 steel with martensitic matrix and the Hadfield steel with austenitic matrix were investigated. Abrasive wear tests, using a wet rubber wheel abrasion tester, were carried out using abrasive sizes between 0.15 and 2.40 mm and pH values of the aqueous solution between 5.5 and 12.8. The microstructures of the materials studied were analyzed by optical microscopy and the wear surfaces and wear particles were analyzed by scanning electron microscopy. The hardness and microhardness before and after the tests were measured using a Vickers hardness tester. The topography of the middle of wear scars, were obtained by a noncontact 3D profiler in order to measure the depth of abrasive penetrations.The results show that the Hadfield steel is more wear resistant than the H-13 steel at all pH values and abrasive sizes conditions tested. For both materials, mass loss increases linearly up to a critical abrasive size, and after this the mass loss continues to increase, but with a lower intensity. Moreover, for both materials and all the abrasive sizes, increases in the pH values of the aqueous solution resulted in lower mass losses, and this effect is greater for the two smaller grain sizes. For higher pH values, lower depths of penetration of abrasive were observed. The microhardness in the wear scar surface of the H-13 steel presented a slight increase with the abrasive size, while for the Hadfield steel, this microhardness increases in a more intense form with the abrasive size. The analysis of the wear particles showed that, for all test conditions, the chips of H-13 steel has two types of morphologies, continuous or discontinuous, and for Hadfield steel only discontinuous. For both materials, two abrasive wear micromechanisms were observed, microcutting and microploughing. Finally, the results presented in this work suggest that the wear performance analysis of the Hadfield steel, to be used in an abrasive environment, must consider the effects of pH of the aqueous solution and particle size.