京都大学 / 新制・課程博士 / 博士(工学) / 甲第23181号 / 工博第4825号 / 新制||工||1754(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 高岡 昌輝, 教授 橋本 訓, 准教授 大下 和徹 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Orientador: José Geraldo Nery / Resumo: A busca por novos materiais, principalmente materiais que apresentem múltiplas aplicações, continua atraindo pesquisas ao redor do mundo. Dentre os materiais pesquisados com esse intuito, os compósitos ganham destaque. Compósitos são materiais mistos formados pela união de dois ou mais materiais diferentes com a finalidade de produzir um material novo com propriedades distintas, em relação aos seus materiais de origem. Os compósitos podem ser aplicados em diferentes áreas, entre elas encontram-se a remediação ambiental e a hemostasia. A remediação ambiental se faz necessária principalmente pelo fato de que muitas fontes hídricas acabam sendo poluídas por resíduos nocivos a saúde humana e animal, como metais pesados, e o consumo destas águas acaba causando sérias doenças. Devido a isso a busca por agentes capazes de retirar estes poluentes da água torna-se necessária. Outro grande problema de saúde publica são as hemorragias incontroladas que continuam sendo umas das principais causas de mortes no mundo. Neste contexto, o objetivo deste trabalho foi sintetizar um compósito que apresente a capacidade de atuar tanto como agente de remediação ambiental como agente hemostático. O compósito foi sintetizado utilizando zeólita e quitosana como suas matrizes. O material foi caracterizado por Difração de Raios-X; Espectroscopia de Infravermelho e Microscopia Eletrônica de Varredura. O potencial de ação ambiental foi testado analisando a absorção de cátions de cádmio e chumbo, presentes... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The search for new materials, especially materials with multiple applications, continues to attract research from around the world. Among the materials researched for this purpose, composites stand out. Composites are mixed materials formed by joining two or more different materials in order to produce a new material with distinct properties relative to their source materials. Composites can be applied in different areas, including environmental remediation and hemostasis. Environmental remediation is necessary mainly due to the fact that many water sources end up being polluted by waste harmful to human and animal health, such as heavy metals, and the consumption of these waters ends up causing serious diseases. Because of this the search for agents capable of removing these pollutants from water becomes necessary. Another major public health problem is uncontrolled bleeding, which remains one of the leading causes of death worldwide. In this context, the objective of this work was to synthesize a composite that presents the ability to act as both environmental remediation agent and hemostatic agent. The composite was synthesized using zeolite and chitosan as their matrices. The material was characterized by X-ray diffraction; Infrared Spectroscopy and Scanning Electron Microscopy. The environmental action potential was tested by analyzing the absorption of cadmium and lead cations present in aqueous solution by the material, and the possible hemostatic application of the ma... (Complete abstract click electronic access below) / Mestre

[pt] As nanopartículas fluorescentes são uma classe de compostos bastante recente e fascinante. Entre estas nanopartículas, têm-se os semicondutores quantum dots - QD (nanopartículas de confinamento quântico) e, as novas nanopartículas carbono dots, CD (nanopartículas de confinamento quântico baseadas em carbono). As nanopartículas fluorescentes podem ter várias utilidades, particularmente em análises químicas, como sensores e em biotecnologia. Ao contrário dos semicondutores QD, que possuem metais tóxicos no seu núcleo, nanopartículas de carbono não contêm componentes tóxicos, sendo vantajosas biologicamente e biodegradáveis. Os CDs têm área superficial muito alta (até 3600 m2/g) com vários grupos funcionais, que podem ser usados para imobilização na superfície de um suporte. Estes vários grupos funcionais influenciam as propriedades óticas dos CDs. Como estas propriedades podem ser mudadas em função do ambiente químico, conferem aos CDs uma característica notável na aplicação em sensores. CDs formam suspensões muito estáveis em meio aquoso, podendo ser sintetizados a partir de vários compostos moleculares, tais como sacarose, glicose, ureia, ácido cítrico, entre outros. Como as propriedades físico-químicas e óticas dos CDs dependem de seus precursores, tem-se em vista neste trabalho: a exploração do uso de aminofenol como precursor na síntese de CDs via solvólise hidrotérmico até os nanomateriais obtidos atingirem fluorescência vermelha dos nanomateriais obtidos; efetuar a purificação dos nanomateriais sintetizados, no seu limite; realizar a caracterização morfológica e estrutural dos CDs obtidos, através de diferentes técnicas físico-químicas, avaliando as suas propriedades fotoluminescentes; desenvolver a metodologia de imobilização covalente dos CDs na superfície de sílica gel mesoporosa; e estudar se o material híbrido pode ser aplicado como adsorvente. Imagens de Microscopia de Força Atômica indicam partículas entre 1,0 e 7,0 nm, e dependem do solvente, já que as partículas menores aparentam dispersão melhor em solvente menos polares. Os espectros de UV-Vis e de Fluorescência confirmam a presença de CDs com transições pi - pi asterisco em acetato de etila, a 290 nm, e em heptano, a 278 nm. O deslocamento batocrômico com o pico de emissão variando de 501 nm a 535 nm com a mudança de solvente, indica que este pode ser utilizado para avaliar a polaridade local, por exemplo, em biopolímeros. Variados suportes de sílica–gel (octadecil, mercaptopropil, aminopropil e SiO2) foram utilizados no estudo de adsorção. Os resultados apontam para um processo de cinética de segunda ordem, sob o modelo de Langmuir, indicando maior afinidade dos CDs com a aminopropil-sílicagel. No estudo foi apresentado que o tratamento térmico da aminopropil-sílicagel (SiO2-NH2) com CDs adsorvidos leva à imobilização de CDs à superfície de suporte através de ligações covalentes. Como este material híbrido (SiO2-NH2/CDs) exibe propriedades de adsorção para metais e compostos poliaromáticos, foi estudada a adsorção de uma mistura contendo 23 cátions metálicos em SiO2-NH2/CDs e o efeito da acidez do meio na sorção de íons. Os resultados obtidos em solução aquosa demonstraram que íons com afinidade por ligantes oxigenados, tais como Bi, Tl, Cr, Al, Fe, são melhor adsorvidos no material sintetizado. / [en] Fluorescent nanoparticles are a very new and fascinating class of compounds. Among these are the semiconductors quantum dots (quantum confinement nanoparticles - QD) and also the new types of nanoparticles that are generally called carbon dots, CD (carbon based quantum confinement nanoparticles). Fluorescent nanoparticles can have several uses, particularly in chemical analysis: as sensors and in biotechnology for drug delivery and theranostics. Unlike QD semiconductors that have toxic metals in their core, carbono nanoparticles do not contain toxic components, being biologically beneficial and biodegradable. CDs have a very high surface area (up to 3600 m2/g) with various functional groups and can be used for immobilization on the surface of a support. Due to their functional groups, optical properties of CDs can be changed depending on the chemical environment, a notable feature of CDs in sensor applications. CDs form very stable suspensions in aqueous media and can be synthesized from molecular compounds such as sucrose, glucose, urea, citric acid and so on. It is worth noting that physicochemical and optical properties of CDs depend on their precursors. The aim of this work is to explore the use of aminophenol as a precursor in the synthesis of CDs via hydrothermal solvolysis to achieve red photoluminescence of the obtained nanomaterials; carrying out the purification of synthesized nanomaterials, at its limit; perform the morphological and structural characterization of the obtained carbon dots, through different physicochemical techniques, evaluating their photoluminescent properties; to develop the methodology of covalent immobilization of CDs on the surface of mesoporous silica gel, and to study the hybrid material as adsorbent. Atomic Force Microscopy images indicate particles between 1.0 to 7.0 nm depending on the solvent, as smaller particles appear better dispersibility in less polar solvents. The UVVis and Fluorescence spectra confirm the presence of CDs with pi-pi asterisk transitions at 290 nm in ethyl acetate and at 278 nm in heptane, they also indicate a bathochromic shift with the emission peak going from 501 nm to 535 nm with a solvent change, which can be used to assess local polarity, eg in biopolymers. Adsorption was verified using various silica-gel supports (Octadecyl, Mercaptopropyl, Aminopropyl and SiO2) indicating greater affinity with aminopropylsilica-gel, indicating a second-order kinetic process under the Langmuir model. It has been shown that the thermal treatment of aminopropyl-silica (SiO2-NH2) with adsorbed CDs leads to covalent immobilization of CDs to the support surface. This hybrid material (SiO2-NH2/CDs) could exhibit adsorption properties for metals and polyaromatic compounds. Therefore, the adsorption of a mixture containing 23 metals ions on SiO2-NH2/CDs was studied. The effect of the acidity of the medium on ion sorption was studied. It has been shown that ions with affinity for oxygenated ligands (such as Bi, Tl, Cr, Al, Fe) are better collected.

The ongoing energy and environmental crises have pushed the transportation sector, a major greenhouse gas emitter, to seek sustainable fuel and technology alternatives. Natural gas and bio-methane are potential alternatives with numerous advantages over conventional fuels. Adsorbed natural gas (ANG) technology uses porous adsorbent material to store methane efficiently at lower pressures. An issue limiting this technology is the lack of compact tanks with efficient adsorbent packing that increase storage capacity. This study addresses the need for more compact ANG tanks by creating novel binder-less monolithic activated carbon monolith adsorbents with targeted porosity. A template is produced using 3D printing and a commercially available phenolic resin as a filling material. Upon thermal treatment, the 3D-printed template combusts with molecular oxygen in its structure, and the resin is transformed into activated carbon by pyrolysis. Longer activation times led to higher BET surface areas. However, after activation periods beyond 15 minutes, the surface area increase is obtained at the expense of a higher burn-off, which affects the material density. Adsorption of 0.04g/g of methane was measured at 30 bar and 298 K on the activated carbon monolith with the highest BET surface area (516 m2/g). Results in the same conditions on a super high surface area Maxsorb activated carbon were 0.13g/g. Although the methane capacity obtained is lower than in a commercial sample, it was demonstrated that producing an activated carbon monolith with tailored porosity is possible. New techniques for activation should be studied to enhance their gravimetric capacity to make ANG competitive.

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An experimental pressure swing adsorption unit has been constructed and used to investigate the separation of carbon dioxide from carbon dioxide enriched air using both an activated carbon and a type 5A molecular sieve adsorbent. Continuous, cyclic operation was achievedusing a pair of fixed bed adsorbers. At any one time the feed gas entered one bed at a high pressure and part of the purified gas was returned to the other bed at a reduced pressure to provide countercurrent regeneration of the adsorbent. The beds of adsorbent used were each nominally 0.165m diameter and Im. deep. Separations were carried out at approximately ambient temperature using air flow rates in the range 0.15 to 0.95 kg/m2s and inlet carbon dioxide concentrations'in the range 0.1 to 1.5% v/v. Adsorption pressures of 2 to 6.4 bar were examined, the desorption pressure being maintained throughout at essentially 1.0 bar. The period time was varied from 30 to 900 seconds and the revert ratio (i. e. the ratio of the product gas returned for desorption to the total feed rate to the unit) was varied from 0 to 1.0. The carbon dioxide separation efficiency was found to increase markedly as the adsorption pressure and the revert ratio were increased whereas it was relatively insensitive to variations in feed rate and, more particularly, feed concentration. The performance of the molecular sieve adsorbent was found to be very sensitive to the presence of moisture in the feed gas. In contrast the carbon dioxide efficiencies observed with Lhe activated carbon were unaffected by the presence of small amounts (circa 100 ppm) of moisture in the feed. A theoretical model has been proposed for predicting the performance of pressure swing adsorption systems of the type investigated and approximate analytical equations and more precise numerical techniques have been established to represent its solution. The approximate analytical solutions were found to give close agreement with the more precise methods examined under conditions corresponding to low values of a dimensionless period time parameter. The proposed theoretical model incorporates an effective irean mass transfer coefficient to represent the diffusion process within the adsorbent particles. Methods for estimation of the value of this coefficient based on the limiting conditions of a periodic constant surface flux or a periodic constant surface concentration are presented. The experimental performance data were analysed in terms of the proposed analytical solution to give values of the apparent solid phase mass transfer coefficient for comparison with those predicted theoretically. In general the apparent experimental values were consistently less than the predicted values. In addition the relationship between the experimental and predicted coefficients was found to be dependent on both the nature of the adsorbent and a parameter formed by the product of the revert ratio and the adsorption to desorption pressure ratio. Empirical correlating equations which incorporate this dependence are presented.

The main aim of this research is to provide a low cost and sustainable biochar for the removal of organic pollutants from aqueous solution. Wastewater pollution by organic contaminants of emerging concern has become a subject of intense discussion. Removing these contaminants from aqueous solution is paramount to improve water quality for both humans and animal consumption. Traditional adsorption techniques using activated carbon are universal and fast, however, they are very costly. This dissertation therefore seeks to find an alternative low cost adsorbent which can be used to adsorb contaminants from aqueous solution. In chapter one, an overview of some of the selected organic contaminants of emerging concern is given. Pharmaceutical and pesticide entry into the environment, their fate and ecotoxicity are highlighted. Available techniques for the removal of contaminants from aqueous solution are also given. Chapter two is a study on the adsorption of some selected pharmaceuticals using a fast pyrolysis low cost biochar produced from pinewood feedstocks. The pinewood biochar used as the adsorbent in this study was made by fast pyrolysis in an augered reactor at a temperature of 425 oC and a residence time of 20-30 s during bio-oil production. In chapter three, switchgrass biochar has been tested for its potential for remediating water that is contaminated with two phenoxy herbicides, 2,4-dichlorophenoxyacetic (2,4-D) acid and 2-methyl-4-chloro-phenoxyacetic acid (MCPA). The adsorption capacity was remarkable when compared to commercial activated carbon per unit of measured surface area. Furthermore, in chapter four, magnetic and non-magnetic low cost biochars have been tested for the removal of the herbicide metribuzin from aqueous solution under different experimental conditions. The magnetic biochar synthesized from raw switchgrass biochar does not show a detrimental effect on the adsorption capacity. Additional value of this magnetic biochar is the ease of separation from contaminated solution following adsorption.

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Volatile sulfur compounds are cause of concern because, when present in high concentrations, they constitute a danger for health because of their strong toxicity. Furthermore, for low concentrations, they are often a cause of complaint, because of their low odor threshold. In this context, the purpose of this Thesis is to evaluate a new technology for the abatement of sulfur-based malodorous compounds. The investigated technology consists in the use of ozone generating low-pressure UV mercury lamps, operating at room temperature. Hydrogen sulfide is often found in industrial processes, (e.g. WWTPs (Wastewater Treatment Plants), leather production, sewage treatment, garbage disposal, etc). Moreover, it presents both a very high toxicity a low odor threshold. Thus, due to its high representativeness of the case, hydrogen sulfide was chosen as reference compound for the purposes of this project. In order to evaluate a wide range of cases, several experiments using different residence times, humidity contents and inlet concentrations of the pollutant were conducted. The obtained results show that this technology generally presents discrete conversion efficiencies, although not suffcient to be used as freestanding process. For this reason, a pretreatment is revealed to be necessary. The best conversion efficiency was obtained for low flow rates and high moisture content. At the end of the project, as side-study, a possible pretreatment using an adsorbent bed constituted by granular ferric oxide was evaluated.