Dissertations / Theses on the topic 'Xylenol'

O espectrofotômetro, aparelho muito utilizado para realizar leituras de absorbância e/ou transmitância de amostras laboratoriais, pode ser aplicado para a realização de leituras do dosímetro químico Fricke Xilenol Gel. Este aparelho, por possuir componentes eletrônicos avançados e ser importado, apresenta um custo elevado e acaba muitas vezes se tornando um dispositivo inviável para medidas mais simples e rotineiras. O presente estudo implementou-se um aparelho portátil e de baixo custo, para que medidas específicas de absorbância possam ser feitas em laboratórios de ensino de física e que possa ser aplicado como leitor de dosímetros géis, como o acima citado. Este monoespectrofotômetro é constituído por uma fonte LED (próximo a 590 nm), um fotodiodo para avaliação da intensidade da luz transmitida e um display de LCD. Tal leitor permite a comunicação com microcomputadores via porta USB, facilitando o trabalho do usuário para manipular os resultados das medidas. A principal finalidade é voltada para uso acadêmico, no entanto, devido ao seu baixo custo e simplicidade, poderá também ser direcionado para atender outros segmentos como ambulatorial, industrial, cosmético, biológico, agronômico, dentre outros.
The spectrophotometer, a device often used to perform absorbance readings and or transmittance of laboratory samples, can be applied to perform readings in the chemical dosimeter Fricke Xylenol Gel. This device, once it has advanced electronics components and is imported, has an elevated cost and often ends up becoming an impractical device for most simple measurements and routine. This study implemented a device portable and inexpensive, so that specific measurements absorbance can be made in teaching laboratories of physics and that can be applied as a gel dosimeter reader, like the above. This monospectrophotometer consists of a LED source of visible light (near 590 nm), a photodiode to assess the intensity of transmitted light and an LCD display. This reader allows communication with computers via USB port, making it easier for users to manipulate the results of the measurements. The main purpose is directed for academic use, however, due to its low cost and simplicity, may also be applied to attend other segments such as outpatient, industrial, cosmetic, biological, agronomic, among others.

A tomografia computadorizada (CT) representa a maior fonte de exposição aos raios X médicos e seu uso continua crescendo rapidamente, devido aos aparelhos de última geração com alta resolução de contraste. Uma avaliação dos parâmetros que influenciam a dose absorvida na tomografia asseguram o controle de qualidade e aceitação do equipamento. Os protocolos de CT utilizam câmara de ionização e filme radiográfico para esta avaliação e pela primeira vez, neste trabalho, o dosímetro químico Fricke Benzóico Xilenol Gel (FBXG) foi utilizado. Este dosímetro ao ser irradiado, produz um complexo colorido (Fe^{+3}-AX) possível de ser medido através de técnicas ópticas, acústicas e de ressonância magnética. A leitura do filme e FBXG por fotografia, também foi empregada pela primeira vez neste trabalho indicando ser adequada. Da utilização do FBXG para avaliação do CT, foi possível obter os parâmetros de espessura de corte, homogeneidade de campo e curvas de isodose, além da promissora indicação dos índices de dose em tomografia.
Computed tomography now represents the single largest source of medical exposure and its use is increasing rapidly, because of new generation units and hight contrast image. The acceptance and quality control tests of this equipment can be inferred through some parameters that influence the absorbed dose, such as axial and transaxial dose profile and CT dose indexes. Although ionization chamber and radiographic films are indicated by protocols for these evaluations, in this present work, beside this two dosimeters, we use the chemical dosimeter Fricke Benzoic Xylenol Gel (FBXG). This dosimeter when irradiated produces a colored complex (Fe^{+3}-XO), that in this work was measured photographically to obtain the parameters, once this technique as well the FBXG are linearly dependent on the absorbed dose. This reading technique was adequate to obtain the calibration curve, the axial and transaxial dose profile for the FBXG, besides to let us visualize the future acquiring of tomographic dose indexes.

Quando se utiliza feixes de radiação ionizante de fótons e elétrons com altas energias, a região mais perto da superfície do paciente, região de não-equilíbrio, pode ter o comportamento das doses absorvidas comprometido devido a vários fatores como a presença de materiais auxiliares na radioterapia, exemplo o \"bolus\" (para superficializar a dose absorvida) e materiais imobilizadores como a máscara termoplástica. Dependendo da significância da incerteza no valor da dose absorvida, medidas devem ser tomadas para que esta seja mais próxima possível daquela prescrita. O objetivo desse trabalho é o de avaliar a capacidade do FXG para medidas de dose absorvida na região de não-equilíbrio e o comportamento dessas. Os objetivos específicos foram: (1) o de avaliar e comparar os (µ/?) experimentais e simulados (X-COM e GEANT-4) para diversos materiais, incluindo o FXG, (2) avaliar a influência da máscara termoplástica na dose absorvida prescrita e (3) determinar o ponto de equilíbrio eletrônico, R100, em função das energias dos feixes de fótons e elétrons para diversos materiais. Dos resultados obtidos tem-se que o (µ/?) relativo ao FXG é próximo daquele do tecido mole (TM), o material da máscara influencia a distribuição da dose absorvida na região de não-equilíbrio e os valores obtidos experimentalmente e por simulação MathLab® e PENELOPE® , indicam equivalência entre os materiais da câmara de ionização (CI) e Água, diferentes da equivalência do FXG eTM. Esse último resultado corrobora aquele obtido no experimento para determinação do (µ/?) , levando a concluir a adequabilidade do FXG para medidas na região de não-equilíbrio.
When one uses high energies photons and electrons ionizing radiations beam, the region closer to the surface of the patient, non-equilibrium region, can obtain the absorbed dose behavior compromised due to several factors such as the presence of auxiliary materials in radiotherapy, like the \"bolus\" (used to superficialize the absorbed dose) and immobilizing material as the thermoplastic mask. Depending on the significance of the uncertainty in the dose absorbed value, measurements must be taken in order the measured value be as close as possible to that prescribed. The aim of this paper is to evaluate the ability of FXG for the measurements of the absorbed dose in the region of non-equilibrium and their behavior. The specific object ives are: (1) to evaluate and compare the µ/? experimental and simulated (X-COM and GEANT-4) for various materials, including the FXG; (2) to evaluate the influence of the therm oplastic mask in the prescribed absorbed dose, and (3) to determine the equilibrium electronic point, R100, depending on the photon and electron beam energies for various materials. The results present that the FXG µ/? is close to that of the soft tissue (TM); the mask material influences the absorbed dose distribution in the non-equilibrium region, and the values obtained experimentally and also through MatLab® and Penelope® simulation indicate equivalence between the materials of ionization chamber (IC) a nd water, different from the equivalence between the FXG and TM. This last result corroborates the obtained one in the experiment for the µ/? determination, suggesting the adequacy of FXG for measurements in the non-equilibrium region.

Em radioterapia, dependendo do tamanho do volume alvo a ser irradiado, pode ser necessário mais de um feixe de radiação (fótons ou elétrons). Isto faz com que sobreposições dos feixes, tanto na superfície (campos de radiação) quanto em profundidade (composição das penumbras) resultem em sobredosagens que podem interferir nos tratamentos e restabelecimento dos pacientes. Para se evitar a sobredosagem foram criados os gaps (espaçamento ou distanciamento entre os campos dos feixes, na superfície de entrada dos mesmos) com a finalidade de diminuir a sobredosagem e homogeneizar a dose absorvida dentro de valores aceitáveis, que não devem exceder 20% acima do valor esperado. Para feixes de elétrons não há a prática do uso de gap, como para feixes de fótons, e não há equações que possam prever a sobredosagem na adjacência desses feixes, assim como não há um estudo mais aprofundado das técnicas possíveis de serem utilizadas para se evitar a sub e/ou sobredosagem desses feixes na superfície e em profundidade. Com isto, este trabalho foi estruturado visando à obtenção da homogeneidade das doses absorvidas na região de adjacência dos feixes de elétrons, partindo do conhecimento da aplicação de gaps para feixes de fótons. Para tal, foi desenvolvido um protótipo de leitura dos dosímetros FXG e filme radiocrômico, baseado no sensor Charge-Coupled Device (CCD). Esse protótipo permitiu fazer as medidas de diversos feixes de fótons e elétrons, variando suas energias, geometrias e superfícies de entrada (plana e/ou curvas), cujas respostas puderam ser comparadas com as obtidas por simulação por Método Monte Carlo (MMC), resguardando as mesmas condições de feixes e arranjos experimentais. Dos resultados obtidos, pode-se comprovar: a eficácia do protótipo desenvolvido, o desenvolvimento de uma equação para prever a sobredosagem advinda da adjacência de feixes de elétrons a partir de dados experimentais, a reversão do uso da equação de gap específica para feixes de fótons para feixes de elétrons em superfícies planas, a equivalência dos resultados da simulação por MMC com os experimentais de gap realizados, além da adequabilidade dos filtros compensadores (em cunha) desenvolvidos para superfícies de entrada curvas. Todos esses resultados indicam a possibilidade da utilização do gap para feixes adjacentes de elétrons em superfícies planas e filtros em cunha em superfícies curvas, passíveis de serem utilizados na prática radioterápica.
Radiotherapy of extensive volumes normally is made using more than one radiation beam (photons or electrons). These beams once are divergent, in the intersection of their penumbra the isodose composition value is increased increasing the absorbed dose value in the treatment region. To overcome this effect is used the \\textit (a shift between the beam fields at the entrance surface) whose scope is to homogenize the depth absorbed dose and do not let it to exceed 20% of its expected value. Only for photons exists the practice of gap (with equations predicting gap for plane surfaces) and compensator filters (for curve surfaces). Once these ideas are non existent for electron adjacent beams and once the use of this type of radiation has increased along the years for patient irradiation, most of the times replacing the photon beams, the curiosity to obtain methods to minimize the overdose due to the electron adjacent beams was triggered and turn it the goal of this research. For this work two dosimeters were used (Fricke Xylenol Gel, FXG and Radiocromic film) and their measurements were made through a developed prototype with a Charge-Coupled Device, CCD, whose results were compared also with Monte Carlo simulations considering the same experimental conditions (irradiation geometry, beam energy, entrance surface geometry, plane and/or curve, and setup). From the results obtained one could notice that: the CCD prototype resulted in an adequate device to be used with the selected dosimeters, the gap equation for photons could be used successfully also for adjacent electron beams on plane surfaces, compensator filters (acrylic wedge filters) are adequate for curve surfaces and the Monte Carlo Simulation results shown equivalence with the experimental ones. All these results encourage the gap for electron adjacent beams on plane surfaces, as well the use of wedge filters for curve surfaces in radiotherapy practice.

A International Comission on Radiation Units and Measurements (ICRU) recomenda que a incerteza total de um tratamento radioterápico não deva ultrapassar de 5%, ou seja, cada etapa do processo de entrega da dose absorvida ao volume alvo do paciente tenha incerteza menor que esse valor (ICRU 50, 1993; ICRU 62, 1999). O cuidado com essas incertezas inicia-se na instalação da máquina (neste caso, de um Acelerador Linear Clínico), passando pela sua aceitação, pelo comissionamento, perdurando nos controles de qualidade posteriores e até em novos comissionamentos, se necessários. Os parâmetros físicos dosimétricos mínimos necessários a serem comissionados para feixes de fótons e elétrons são: Porcentagem de Dose em Profundidade (PDD), Perfis de Campos abertos e filtrados, Fatores de Espalhamento Total (Scp), Cone (Fcone) e de Transmissão (de Filtros em cunha FF, Bandeja FB, e de Transmissão intra FMLC,intra e de fuga inter lâminas FMLC,inter), além da Determinação da Posição Virtual da Fonte de Elétrons através da SSD efetiva (SSDeff). Para tal, a American Association of Physicists in Medicine (AAPM), através do seu protocolo mais recente, apresenta objetos simuladores, tipos e tamanhos de detectores, arranjos e procedimentos experimentais específicos, através dos quais é possível inferir os parâmetros dosimétricos de feixes de fótons e elétrons, usando varredura destes com câmara de ionização (CI), considerando o erro total das medidas menor do que 1% (AAPM TG 106, 2008). Entretanto este mesmo protocolo cita de maneira sucinta ou pouco detalhada, a possibilidade da utilização de dosímetros tipo gel para o citado comissionamento, já que possuem diversas vantagens a serem consideradas na Radioterapia, como equivalência ao tecido mole (Z e ), independência energética num amplo intervalo de energia de fótons e elétrons, além da alta resolução espacial. Desta forma, o objetivo geral deste trabalho é apresentar de forma inédita, o comissionamento dos parâmetros físicos dosimétricos de aceleradores lineares clínicos (PFDALC), especificamente através do dosímetro Fricke Xilenol Gel (FXG), como método alternativo e/ou complementar aos internacionais vigentes. Para tal, neste trabalho foram desenvolvidos dispositivos e procedimentos que proporcionassem aos usuários uma forma prática, eficiente e de baixo custo para obtenção dos parâmetros citados através do FXG, em relação aqueles obtidos com a CI (método padrão). Todos os resultados dos parâmetros físicos dosimétricos obtidos com o dosímetro citado foram validados com a CI, considerando a incerteza preconizada para a mesma. Esses resultados sugerem que o FXG efetivamente poderá ser utilizado para o comissionamento de aceleradores lineares clínicos e que um protocolo específico para este dosímetro poderá ser gerado.
The International Commission on Radiation Units and Measurements (ICRU) recommends that the total radiotherapy treatment uncertainty should not exceeds 5%, in other words, considering that each step involved in the absorbed dose delivery process should not surpass the cited value (ICRU 50, 1993; ICRU 62, 1999). The uncertainties considered are those involved with, the machine installation (in this work, a Clinical Linear Accelerator), its acceptance, commissioning, followed by those related to subsequent quality controls and even new commissioning, if necessary. The minimum required physical dosimetric parameters to be commissioned for electron or photon beams are: the Percentage Depth Dose (PDD), the filtered and open Field Profiles, Total Scatter Factors (Scp), Cone Factor (Fcone), Transmission Factors: Wedge Filter (FF), Tray (FB), intra Leaf (FMLC,intra) and inter Leaf Leakage (FMLC,inter), besides the Virtual Source Position Determination (SSDeff). For this purpose, the American Association of Physicists in Medicine (AAPM), through its last protocol, provides guidelines on phantom and detector selections, setting up of phantom for data acquisition (for scanning and no-scanning data), procedures for acquiring the cited beam parameters with ionizing chambers (CI) and methods to reduce the total measurement error lower than 1% (AAPM TG 106, 2008). However, this protocol does not present any information or details about the physical dosimetric parameters for clinical linear accelerators (PFDALC), through gel dosimeters once they present several useful advantages for Radiotherapy, such as: soft tissue equivalence (Z and ), wide energy independence range for photons or electrons beams and high spatial resolution. The scope of this work is to present an innovative way for physical dosimetric parameters commissioning, specifically using the Fricke Xylenol Gel (FXG) dosimeter, like an alternative and/or complementary method to that employed internationally. Devices and procedures have been developed for this work in order to infer the cited parameters, in a practical, efficient and low cost way, compared to that used with CI (standard method). All the FXG results obtained were validated with the CI, considering the uncertainty recommended for the last one. The results suggest that the FXG effectively can be used for physical dosimetric parameters commissioning for clinical linear accelerators and a new specific protocol can be generated.

The objective of this study was the calculation and optimalization methods of the indirect spectrophotometric determination of fluoride based on the zirconium complex. Three organic reagent eriochromcyanin R chromazurl S and xylenol orange were tested. As the most sensitive system was shown the complex of zirconium with xylenol orange. Linear standard curve was ranged from 1,5.10-6 to 7,5.10-5 mol.dm-3. H2PO4-, Fe3+ and the highest concentrations of Fe2+, SO42- were tested for interferent. The Fe2+ and SO4- interfere only above the concentration which cannot be found in natural water. The optimized method was applied for the determination of fluoride in the model and real drinking, mineral and surface water.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

A Doença Enxerto Contra Hospedeiro Associada à Transfusão (DECH-AT) é uma reação transfusional rara, porém fatal, que ocorre devido à presença de células T no sangue doado e que pode ser prevenida por meio da irradiação do sangue do doador e de seus componentes antes da transfusão. Assim, o controle de qualidade associado à irradiação do sangue é necessário para se garantir a qualidade do produto transfundido. Neste trabalho é proposta a caracterização e a adaptação da resposta do dosímetro Fricke para uso na dosimetria da irradiação de sangue, mais especificamente o Fricke Xilenol Gel (FXG). Este é um dosímetro químico radiocrômico, que apresenta as vantagens de ser tecido equivalente e de permitir a inferência espacial da dose absorvida dentro da faixa de doses usados na prevenção DECH-AT. Dessa maneira, de modo a possibilitar a inferência de dose absorvida em todo o intervalo utilizado na prevenção da DECH-AT (25 a 50 Gy), o FXG foi caracterizado e adaptado para aplicações dosimétricas envolvendo a irradiação de sangue e derivados. Os resultados com o novo dosímetro apontaram adequabilidade para toda a faixa necessária de doses absorvidas, com sensibilidade e desvanecimento temporal satisfatórios para aplicações rotineiras. Além disso, pela metodologia proposta neste trabalho, foi possível determinar as distribuições espaciais das doses absorvidas com o dosímetro proposto de uma maneira rápida e simples, mostrando assim que este dosímetro apresenta características convenientes para o controle de qualidade para a dosimetria da irradiação de sangue e de hemocomponentes.
The Transfusion Associated Graft Versus Host Disease (TA-GVHD) is a rare transfusion reaction, however fatal, which develops due to the presence of donor T lymphocytes in the donated blood and that can be avoided by the irradiation of the donated blood blood and blood components prior to transfusion. Thus, the associated quality control of blood irradiation is necessary to guarantee the quality of the transfused product. In this work it is proposed the characterization and adaptation of the response of a Fricke dosimeter to be used for dosimetry of blood irradiation, more especiafically the Fricke Xylenol Gel (FXG). This is a radiochromic chemical dosimeter, which presents advantages to be tissue equivalent and allows the spatial absorbed dose inference. In this manner, in a way to possibilitate the absorbed dose inference in the full interval used for the prevention of the TA-GVHD (25 to 50 Gy) the FXG was characterized and adapted for dosimetry applications involving blood and blood components irradiation. The results with the new dosimeter showed adequability for the necessary absorbed doses, with satisfactory sensibility and time fading for routine applications. Furthermore, according to the methodology proposed in this work, it was possible to determine the spatial absorbed dose distributions with the new dosimeter in an fast and simple way, showing that this dosimeter presents convenient characteristics for dosimetry quality control of irradiated the blood and blood components.

Includes bibliographical references (p. 177-183)
The idea behind this research was to add value to such C₉˖-polymethylphenol isomer mixtures by converting them into high value cresols and xylenols via transalkylation with phenol over acid zeolite catalysts. This would comprise recovery of the valuable aromatic (phenolic) OH-groups present in the constituents of the C₉˖-phenolics fraction and also make use of the C₉˖-polymethylphenols as an active-and cheap-reagent for the methylation of the phenol, due to the activation of their aromatic rings by the OH-group. Tanslkylation reactions were carried out in liquid phase at 60 bar in a continuously operated, isothermal, tubular laboratory scale reactor over 6 g of acid zeolite catalyts were screened, H-MFI, H-MOR and H-BEA.

A range of different heterogeneous catalysts for the isomerisation of ortho-xylene have been prepared and evaluated. These included commercially-available samples, supported metal catalysts and zirconia-based catalysts. The greatest activity was seen for the former, which was found also to be active for a number of related reactions. Zirconia-based catalysts, in particular sulphated zirconia, gave significant activity. It was possible to prepare a catalyst to give 9.5% conversion of ortho-xylene per gram of catalyst with good selectivity to the meta isomer. The catalyst was prepared in two ways, either by the action of ammonium sulphate on "zirconium hydroxide", a hydrated zirconia precursor, or by precipitation from a sulphuric acid-containing solution of zirconium (IV) propoxide. The factors in the synthesis procedure which affect the catalytic performance of the catalyst were investigated. These included choice of reagents, preparative method and calcination procedure. This information was used to prepare an 'idealised' catalyst, which showed activity for a number of reactions of commercial interest. A range of different aminophosphine complexes based on the reaction of a N,N'- substituted diamine with chlorodiphenylphosphine have been prepared for subsequent study as ligands in complexes active in homogeneous catalysis. Palladium and platinum complexes of the type [(diaminodiphosphine)MCl(_2)] have also been prepared and characterised. A number of x-ray diffraction analyses have been performed, which along with other data has allowed the solid state and solution structures to be discussed. The relative reactivities of the ligands have been determined by reactions with manganese pentacarbonyl bromide and also with palladium dichloride complexes. This depends largely on the steric requirements of the ligand in question. The potential of these ligands in catalysis has been evaluated by the performance of their platinum dichloride complexes in the tin (II)-promoted hydroformylation of styrene, and their palladium acetate complexes for the methoxycarbonylation of ethene.

The research was concerned with obtaining kinetic data and product information for the oxidation chemistry of the isomeric xylenes and benzyl radicals at 753K. A trace amount (0.01 % for kinetic study, 0.5% for product study) of each xylene was separately added to slowly reacting mixtures of H₂ + O₂ in aged boric-acid-coated Pyrex reaction vessels at 753K and 500 Torr total pressure. From measurements of the relative loss of H₂ and hydrocarbon rate constants for the reactions of the radicals H and H0₂ with each xylene were obtained. H + Xylene → Products k=1.3* 10⁹ 1 mol¯¹ S¯¹ (p-xylene), 1.4*10⁹ I mol¯¹ S¯¹ (m-xylene), 1.8* 10⁹ 1 mol¯¹ S¯¹ (a-xylene). HO₂ + Xylene → Products k=9.4*10⁴ I mol¯¹ S¯¹ (p-xylene), 1.03*10⁵ 1 mol¯¹ S¯¹ (m-xylene), 1.2*10⁵ 1 mol¯¹ S¯¹ (o-xylene). A detailed examination of the reaction products was carried out over a wide range of mixture composition. The major aromatic products from the oxidation of the xylenes were the isomeric tolualdehydes, toluene and a-xylylcne oxide (from a-xylene). These were found to be similar to the products formed from the oxidation of toluene at 753K. From examination of the products available it was also possible to obtain more detailed rate constants for the attack of H radicals at each xylene giving specific products. H + Xylene → Methylbenzyl k=7.3*10⁸ 1 mol¯¹ s¯¹ (p-xylene), 8.3*10⁸ 1 mol¯¹ s¯¹ (m-xylene), 1.2*10⁹ 1 mol¯¹ s¯¹ (o-xylene). H + Xylene → Toluene k=5.6*10⁸ 1 mol¯¹ s¯¹ (for all three xylenes). H + Xylene → CH₃-C₆H₃-CH₃ k=9.1 * 10⁶ I mol¯¹ s¯¹ (p-xylene), 8.4 * 10⁶ I mol¯¹ s¯¹ (m-xylene), 9* 10⁵ I mol¯¹ s¯¹ (a-xylene). In the case of H0₂ + RH, thermochemical considerations lead to the conclusion that both abstraction from and addition to the ring will be considerably less energetically favourable than the equivalent reaction of H atoms. Consequently k(HO₂₊xylene) should be taken to be the rate constant for HO₂ + Xylene → Methylbenzyl. The decomposition of neopentylbenzene in the presence of oxygen and propene at 753K and a total pressure of 60Torr in an aged boric-acid-coated Pyrex reaction vessel was used to determine rate constant" for the reactions between H0₂ and benzyl radicals. The decomposition of neopentylbenzene at 753K produced t-butyl and benzyl radicals. The t-butyl radicals react with O₂ to produce HO₂ radicals. The presence of propene was used to determine the concentration of HO₂ radicals by monitoring the rate of production of propylene oxide. From measurement of the yields of benzaldehyde and toluene yields, and the rate of production of propylene oxide, rate constants for the reactions of HO₂ with benzyl radicals producing benzaldehyde and toluene were determined as 4.36* 10⁹ I mol¯¹ s¯¹ and 8.44* 10⁸ I mol¯¹ s¯¹ respectively at 753K. A detailed examination of the products produced from the decomposition of neopentylbenzene in the presence of oxygen showed that the primary products were benzaldehyde, toluene, i-butene and 2-methyl-l-phenylprop-l-ene. The key features highlighted in this research are the similarity in the oxidation chemistry between the xylenes and toluene and the importance of the reactions of the benzyl radical in the oxidation of methyl-substituted benzenes.

Organic/inorganic materials have a high potential to enable major advances in membrane performance. It has previously been impossible to develop polymeric systems with adequate transport properties for xylene purification. Zeolite membranes have been created with the appropriate selectivities; however low productivity, low mechanical durability, and high capital costs have kept these materials from being utilized. So-called mixed matrix hybrid organic/inorganic membranes combine the mechanical durability and cost effectiveness of polymeric membranes with the enhanced performance of zeolitic structures. This project will focus on investigating polymeric and molecular sieve materials for mixed matrix membrane use in xylene isomer separation as a model system. Torlon polyamide-imide has unique properties that should be potentially useful in a mixed matrix composite. Silicalite will be investigated as the dispersed phased given its proven applicability with xylene isomers. The overarching goal is to establish an approach for creation of mixed matrix materials that can be broadly applied to challenging organic separations. This project has three specific goals: (1) characterization of Torlons inherent properties, processing ability, and important transport potential, (2) characterization of zeolite matching properties and the effect of interfacial engineering on these properties, and (3) development of appropriate approaches to combine the sieve and polymer to obtain a hybrid material with properties that match theoretically predicted separation property enhancements relative to the neat polymer. High temperature pervaporation will be used to evaluate material transport properties, as this experimental setup closely mimics the high activity vapor streams found in many industrial xylene processes. The results of this research will be used to develop a protocol for development of future mixed matrix membranes that may be applied to a variety of organic liquid systems.

Thesis (M.S.)--University of Missouri--Rolla, 2007.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 16, 2007) Includes bibliographical references (p. 85-89).

Ce travail est consacre a la modelisation des phenomenes de transfert mis en jeu lors de l'adsorption competitive en phase liquide d'un melange de xylenes dans un adsorbant zeolithique de type y. La diffusion dans le reseau poreux se divise en deux etapes: la diffusion en phase liquide dans les macropores intercristallins et la diffusion en phase adsorbee dans les micropores intracristallins. Ce travail a donc pour but de determiner l'etape diffusionnelle limitante et de mesurer la diffusivite associee. Deux types d'etudes ont ete effectuees: l'adsorption competitive d'un xylene avec l'isooctane et celle du paraxylene avec l'orthoxylene. Pour mener a bien cette etude, nous avons developpe et mis au point une methode statique de mesure des equilibres et des cinetiques d'adsorption. Les experiences ont ete effectuees dans un domaine de temperature compris entre 9c et 50c et pour differentes tailles de grains d'adsorbant (entre 0,3 mm et 0,9 mm). Les courbes d'adsorption transitoire experimentales ont ete simulees par deux modeles de diffusion correspondant aux deux regimes diffusionnels limites a savoir un modele de diffusion moleculaire dans les macropores avec equilibre instantane dans les cristaux et un modele de diffusion microporeuse. L'utilisation de ces modeles cinetiques a necessite une modelisation precise des equilibres d'adsorption. Pour ce faire, un modele d'isotherme, base sur des considerations quasi-chimiques, a ainsi ete developpe pour permettre de tenir compte des specificites du systeme. Ce modele utilise une description de la zeolithe comme une solution solide de cages plus ou moins remplies. La simulation des courbes d'adsorption transitoire par les deux modeles cinetiques a permis de montrer que pour des temperatures superieures a 50c, la resistance diffusionnelle principale se situe dans les macropores. Le passage d'un regime de diffusion macroporeuse a un regime de diffusion microporeuse par diminution de la temperature a aussi ete mis en evidence

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Industriellement, le para-xylene est separe des autres isomeres aromatiques en c#8 par adsorption sur tamis moleculaire zeolithique. Parmi les nombreux tamis utilises, les zeolithes de type faujasite echanges avec du baryum ou du potassium sont reconnues pour leur selectivite particuliere en faveur du para-xylene. Le travail de recherche presente ici s'insere dans une etude generale de l'optimisation de ce processus de separation des isomeres du xylene. Nos travaux ont ete particulierement orientes vers la caracterisation de l'adsorption de melanges de para-xylene et de meta-xylene dans differentes faujasites, afin d'obtenir une connaissance precise des facteurs gouvernant la separation. Pour aborder cette etude, nous avons choisi la simulation numerique de type monte carlo dans l'ensemble grand canonique. Ces simulations nous donnent acces aussi bien a des donnees thermodynamiques d'adsorption, isothermes et chaleurs d'adsorption, qu'a des informations microscopiques concernant la caracterisation des sites d'adsorption et les interactions mises en jeu. La these s'articule autour de deux axes de recherche principaux. D'une part, nous developpons des outils de simulations adaptes a l'etude de l'adsorption de fluides complexes en milieu confine. D'autre part, nous apportons une meilleure comprehension des mecanismes mis en jeu dans la separation des xylenes par adsorption. Nous mettons en evidence les relations existant entre les actions de compensation presents dans les faujasites et les proprietes d'adsorption de ces zeolithes.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2011.
Vita. Cataloged from PDF version of thesis.
Includes bibliographical references.
Chapter 1. Geometric and Functional Versatility of Carboxylate-Bridged Nonheme- Diiron Motifs: sMMO and ToMO. Several metalloenzymes utilize a carboxylate-bridged non-heme diiron motif for dioxygen activation. Despite their conserved diiron active site structures and mechanisms of dioxygen activation, they catalyze a wide range of chemical transformations. These observations suggest that diiron-containing enzymes have distinct active sites and secondary/tertiary environments that are tuned for their dedicated biological functions. Detailed studies of two diiron-containing enzymes in the family of bacterial multicomponent monooxygenases (BMMs), soluble methane monooxygenase (sMMO) and toluene/o-xylene monooxygenase (ToMO), are described. The functions and structures of the three or four components of sMMO and ToMO are summarized. Distinctly different dioxygen activation chemistry and hydrocarbon specificity is observed for these two enzymes. A comparison of these two enzymes provides insight into the evolution of diironcontaining enzymes as well as their differing chemical mechanisms of catalysis. Chapter 2. Role of an Active Site Threonine in the Determination of Distinctive Dioxygen Reactivity in Toluene/o-Xylene Monooxygenase Hydroxylase. Dioxygen activation of toluene/o-xylene monooxygenase hydroxylase (ToMOH) exhibits the formation of a diiron(III) intermediate having unprecedented spectroscopic properties. To evaluate whether an active site threonine plays a role in the determination of the dioxygen chemistry in ToMOH, a T201S variant was prepared by site-directed mutagenesis. We reported the observation of a novel intermediate in the reaction of reduced ToMOH T201 S variant with dioxygen in the presence of its cognate regulatory protein (ToMOD). This species, T201 peroxo, is the first oxygenated intermediate of any toluene monooxygenase to display an optical band. The optical and M6ssbauer spectroscopic properties of the intermediate allowed us to assign it as a peroxodiiron(III) species, similar to Hperoxo in soluble methane monooxygenase hydroxylase (sMMOH). This result indicates that mutation of the T201 to serine altered the dioxygen chemistry of ToMOH in part to be more similar to that of sMMOH. Computational studies suggest that the T201 mutation can greatly perturb the energetics of the enzyme, which might be responsible for the distinct dioxygen reactivity of sMMOH and ToMOH. Structures of the oxygenated intermediates of ToMOH are proposed. Chapter 3. Role of an Active Site Threonine in the Kinetics of Dioxygen Activation in Toluene/o-Xylene Monooxygenase Hydroxylase. To elucidate the role of a strictly conserved T201 residue during dioxygen activation of toluene/o-xylene monooxygenase hydroxylase (ToMOH), T201S, T201G, T201C, and T201V variants of this enzyme were prepared by site-directed mutagenesis. X-ray crystal structures of all variants were obtained. Steady-state activity, regiospecificity, and single-turnover yields were also determined for the T201 mutants. Dioxygen activation by the reduced T201 variants was monitored by stopped-flow UV-vis and M6ssbauer spectroscopy. These studies demonstrated that the same dioxygen activation mechanism is preserved in the T201S, T201C, and T201G variants; however, both formation and decay kinetics of a peroxodiiron(III) intermediate, T201peroxo, were greatly altered, revealing that the T201 residue is critically involved in dioxygen activation. Rate-limiting steps in dioxygen activation of the T201S, T201C, and T201G variants were identified, revealing that T201 plays a major role in proton transfer, which is required to generate the peroxodiiron(III) intermediate. The role of the active site threonine residue in ToMOH is analogous to that of cytochrome P450 monooxygenases, suggesting it as a general threonine-dependent process in Nature to control proton transfer.
(cont.) Chapter 4. Mechanistic Studies of Reactions of Peroxodiiron(III) Intermediates in the T201 Variants of Toluene/o-Xylene Monooxygenase Hydroxylase. Site-directed mutagenesis studies of a strictly conserved T201 residue in the active site of toluene/oxylene monooxygenase hydroxylase (ToMOH) revealed that a single mutation can facilitate kinetic isolation of two distinct peroxodiiron(III) species, designated T201peroxo and ToMOHperoxo, during dioxygen activation. In Chapter 2 and 3, we characterized both oxygenated intermediates by UV-vis and M6ssbauer spectroscopy, proposed structures from DFT and QM/MM computational studies, and elucidated chemical steps involved in dioxygen activation through the kinetic studies of T201peroxo formation. In Chapter 4, we investigated the kinetics of T2 0lperoxo decay to explore the reaction mechanism of the oxygenated intermediates following 02 activation. The decay rates of T201 peroxo were monitored in the absence and presence of external (phenol) or internal (tryptophan residue in I100W variant) substrates under pre-steady-state conditions. Three possible reaction models for the formation and decay of T201perX0 were evaluated, and the results demonstrate that this species is on the pathway of arene oxidation and appears to be in equilibrium with TOMOHperoxo. Chapter 5. Tracking a Defined Route of 0 2-Migration in a Dioxygen-Activating Diiron Enzyme, Toluene/o-Xylene Monooxygenase Hydroxylase. For numerous enzymes reactive toward small gaseous compounds, growing evidence indicates that these substrates diffuse into active site pockets through defined pathways in the protein matrix. Toluene/oxylene monooxygenase hydroxylase (ToMOH) is a dioxygen-activating carboxylatebridged nonheme-diiron enzyme. Structural analyses of the resting state enzyme suggest two possible pathways for dioxygen to access the c-subunit diiron center, a series of hydrophobic cavities or long solvent-exposed channel. To distinguish which pathway is utilized for dioxygen transfer, the dimensions of the cavities and channel were varied by site-directed mutagenesis and confirmed by X-ray crystallography. The rate of dioxygen access to the active site was monitored by measuring the formation rate of an oxygenated intermediate (T 2 01peroxo), a process that is dependent on 02 concentration. Altering the dimensions of the cavity but not the channel drastically changed the rate of dioxygen activation by the reduced enzyme. These results explicitly reveal that the cavities in the ToMOH a-subunit are not merely artifacts of protein packing/folding but rather programmed routes of dioxygen movement through the protein matrix. This conclusion indicates that conformational changes are required during catalysis to form a dioxygen trajectory and that the temporary opening/closing of the cavities control dioxygen transfer. Given that the cavities are present in all BMMs, the breathing motion presumably controls dioxygen consumption in all BMMs. This study represents the first approach to track kinetically a defined transient pathway by which a small gaseous molecule gains access to a diiron enzyme.
(cont.) Appendix A. Insights into the Different Dioxygen Activation Pathways of Methane and Toluene Monooxygenase Hydroxylases. The methane and toluene monooxygenase hydroxylases (MMOH and TMOH, respectively) have almost identical active sites, yet the physical and chemical properties of their oxygenated intermediates, designated P*, Hperoxo, Q and Q* in MMOH, and ToMOHperoxo in toluene/o-xylene monooxygenase hydroxylase (ToMOH), are substantially different. We review and compare the structural differences in the vicinity of the active sites of these enzymes and discuss the differences that give rise to the distinct behavior of dioxygen reactivity in sMMOH and ToMOH. In particular, analysis of multiple crystal structures reveals that T213 of MMOH and analogous T201 of TMOH, located in the immediate vicinity of the active site, have different rotamer configurations. We study the rotation energy profiles of these threonine residues with the use of molecular mechanics (MM) and quantum mechanics/molecular mechanics (QM/MM) computational methods and put forward a hypothesis according to whether T201 and T213 play an important role in the formation of different types of peroxodiiron(III) species in MMOH and ToMOH. The hypothesis is indirectly supported by QM/MM calculations of the peroxodiiron(III) models of ToMOH and the theoretically computed M6ssbauer spectra. It also helps explain the formation of two distinct peroxodiiron(III) species in the T201S mutant of ToMOH. Additionally, a role for the regulatory protein (ToMOD), which is essential for oxygenated intermediate formation and the protein functioning in the ToMO system, is advanced. Appendix B. Multiple Roles of Component Proteins in Bacterial Multicomponent Monooxygenases: Phenol Hydroxylase and Toluene/o-Xylene Monooxygenase from Pseudomonas sp. OX1. Phenol hydroxylase (PH) and toluene/o-xylene monooxygenase (ToMO) from Pseudomonas sp. OXI require three or four protein components to activate dioxygen for the oxidation of aromatic substrates at a carboxylate-bridged diiron center. In this study, we investigated the influence of the hydroxylases, regulatory proteins, and electron-transfer components of these systems on substrate consumption and product generation. Single-turnover experiments revealed that only complete systems containing all three or four protein components are capable of oxidizing phenol, a major substrate for both enzymes. Under ideal conditions, the hydroxylated product yield was -50% of the diiron centers for both systems, suggesting that these enzymes operate by half-sites reactivity mechanisms. Single-turnover studies indicated that the PH and ToMO electron-transfer components exert regulatory effects on substrate oxidation processes taking place at the hydroxylase active sites, most likely through allostery. Steady state NADH consumption assays showed that the regulatory proteins facilitate the electron-transfer step in the hydrocarbon oxidation cycle in the absence of phenol. Under these conditions, electron consumption is coupled to H20 2 formation in a hydroxylase-dependent manner. Mechanistic implications of these results are discussed.
by Woon Ju Song.
Ph.D.

A series of bench-scale experiments was carried out to determine the rate and efficiency with which benzene and p-xylene, components of gasoline, could be removed from an unsaturated soil by air stripping. Glass columns, 30 cm in length, were packed with soil and wetted to volumetric moisture contents of 10 and 18 percent. Air saturated with one of the volatile organic compounds (VOCs) was used to load the column. Clean air was used to strip the contaminant from the soil. Benzene and p-xylene concentrations in the soil water and air were reduced four orders of magnitude after a few hours (2-8) of stripping. Benzene was removed faster than p-xylene. Air flow was the rate-limiting step early in the stripping, however slow desorption from the soil became rate-limiting as the stripping progressed. As moisture content increased the rate of removal of both contaminants decreased.

Novel water-dispersed polyurethanes based on tetramethyl xylene diisocyanate (TMXDI), polycaprolactone or polytetramethylene glycols and alipbatic diamine chain extenders were synthesised. 2,2-bis(hydroxymethyl) propionic acid (DMPA) and triethylamine (TEA) were used respectively as potential carboxylic anionic emulsifying centres and neutralising agent in the resulting aqueous phase to form pendent quaternary ammonium salts. These were necessary to provide high hydrophilicity to the polyurethanes sufficient to make the polyurethanes easily dispersed in water without the assistance of organic solvent.

碩士
長庚大學
化工與材料工程研究所
97
In this study, DF (distillative freezing) is firstly applied to separate the binary mixture of m-cresol and 2,6-dimethylphenol. Then, DF is introduced to purify m-cresol and 2,6-dimethylphenol from the quaternary mixture consisting p-cresol, m-cresol, o-cresol and 2,6-dimethylphenol. The experimental results show that 2,6-dimethylphenol can be purify from 90 wt% to 99 wt% in the binary mixture of m-cresol and 2,6-dimethylphenol. The recovery rate ranges from 18% to 60% depending on the operating temperature and pressures. However, it is difficult to purify m-cresol in the binary mixture of m-cresol and 2,6-dimethylphenol by DF. In the quaternary mixture, the experimental results show that 2,6-dimethylphenol can be purify from 90 wt% to 98 wt%. The recovery rate ranges from 26% to 37%. It is also difficult to purify m-cresol in the quaternary mixture by DF. DF is operated at triple point condition, in which the liquid mixture is simultaneously vaporized and crystallized due to the three-phase equilibrium. Thus, DF combines distillation and crystallization to produce pure crystals. The process can be continued until the liquid phase is completely eliminated and only the pure solid crystals remain in the feed. Thus, filtration or centrifugation is not needed to separate the solid crystals from the mother liquor since no mother liquor is present with the pure crystals.

碩士
國立成功大學
化學系碩博士班
94
This thesis is related to the detection of cobalt ions using solid state sensors. Three different TiO2 substrates with chemically-adsorbed xylenol orange tetrasodium salt (XO) are used as sensors. The detection of cobalt ions is based on the change in visible absorptions. The visible absorption of XO/TiO2 is not sensitive to pH change, so there is no need to use buffer solutions in the cobalt ions detection. Mesoporous TiO2 is found to have the best sensitivity to cobalt ions among the three different TiO2 samples, owing to its higher surface area. Using the XO/mesoporous TiO2 as a sensor, the cobalt ions detection limit are 2X10-4M(12ppm) based on the color change observed by naked eyes. It is decreased down to 10-5M(0.6ppm) with spectrophotometric change. Fourier transform infrared spectroscopy is employed to investigate the bonding of cobalt ions on XO/TiO2 . It is found that the vibrational motions of N(CH2)3 , OH, and benzene rings of XO molecules are largely perturbed . This result may alike reflect the bonding sites of the XO molecules interacting with cobalt ions.

碩士
國立成功大學
化學系碩博士班
95
In this research, the role of xylenol orange employed as a sensor molecule for Co2+ ions was investigated. The absorption of UV-Vis light of XO molecules in an aqueous solution was significately affected by the pH value. XO-TiO2 films, prepared by immersion of TiO2 films in XO aqueous solutions at pH = 6-7, showed changes in color and reflectance of visible light with addition of Co2+ solutions. It was found that the reflectance change at 588nm (ΔF(R)) due to the addition Co2+ solutions of different pH values could be divided into four ranges, pH~1-3; pH~5-8; pH~9-11; pH~12-13, and the ΔF(R) within each range was about the same. Linear relations of ΔF(R) vs Co2+ concentration were obtained with XO-TiO2 as sensing films. The minimum concentration of Co2+ that could be judged by the color change with naked eyes was ~2.24 ppm(mg/L). Molecular dynamics simulations were employed to study the coordinated structure of Zn2+ in XO aqueous solutions. Based on the most probable distances from the Zn2+ ions to the specific atoms or function groups of XO molecules, the Zn2+-XO complexes might have a structure of four 9-membered rings and two 8-membered rings.

碩士
國立中央大學
化學工程學系
84
In this research, we mainly study the solid-liquid equilibria of 2,6-xylenol+m-cresol, 2,6-xylenol+tert-butanol and m-cresol+ tert-butanol binary systems at the atmospheric pressure. We applied solid disappearance method to measurethe melting points of the above binary systems. We obtained experimental data of 2,6-xylenol+tert-butanol mixture different from those of Jadhav et al.(1991). Our experimental data show, the eutectic point occurs at 0.321 mole fraction of 2,6-xylenol and eutectic temperature at 253.68K, but Jadhav et al.(1991)showed the eutectic composition of 0.271 and the eutectic temperature at 251.35 K. To ensure the reliability of our data,Differential Scanning Calorimeter(DSC), was used to measure the melting point. The result is far from that of Jadhav et al.(1991). We found that there are two eutectic points (x1=0.489 and x1=0.772) and one congruent point (x1=0.689) for the system of m- cresol(1)+tert-butanol(2). We found that the mixture of 2,6-xylenol and m-cresol exhibited an unusual behavior of thermal minimum that was very different from eutectic point.But this needs to be examined carefully. Finally, we correlated the experimental data for systems containing one eutectic point by Wilson Model, van Larr Theory, NRTL Model and Regular Solution Theory to predict the behavior of the solid-liquid equilibrium and find the NRTL is better than others. We correlated the system containing one congruent point by Ideal Chemical Model( ICM).Unfortunately, the experimental data and correlation results do not agree each other very well at the two ends of the phase diagram.

碩士
長庚大學
化工與材料工程研究所
96
The mixed xylenes mainly consist of p-xylene (PX), m-xylene (MX), o-xylene (OX) and ethylbenzene (EB). Due to the close boiling points among the mixed xylenes (e.g., PX=138.37℃、MX =139.12℃、OX=144.41℃ andEB=136.19℃), it is very difficult to separate and purify them. A new separation technique, called distillative freezing (DF), is introduced in this work to purify PX from the mixed xylenes. Basically, DF is operated at triple point condition, in which the liquid mixture is simultaneously vaporized and solidified due to the three-phase equilibrium. A simulation method is proposed to provide essential information in operation of the DF process. The DF experiments show that PX can be successfully separated from the mixed xylenes. Generally, the final purity of PX product can reach from the mixed xylenes with PX ranging from . The actual recovery rates ranges from 50% to 60%.

碩士
長庚大學
化工與材料工程研究所
96
Xylenes have very broad applications in chemical industries. The mixed xylenes mainly consist of p-xylene (PX), m-xylene (MX), o-xylene (OX) and ethylbenzene (EB). Due to the close boiling points among the mixed xylenes (e.g., MX = 139.12℃, PX = 138.37℃, OX = 144.41℃ and EB = 136.19℃), it is very difficult to separate and purify them. Distillative freezing (DF), is introduced in this work to purify OX from the mixed xylenes. Basically, DF is operated at triple point condition, in which the liquid mixture is simultaneously vaporized and solidified due to the three-phase equilibrium. A simulation method is proposed to provide essential information in operation of the DF process. The DF experiments show that OX can be purified from (Xox)0 = 0.90 ~ 0.95 to (Xox)f ≧ 0.99 with RE = 65 % or from (Xox)0 = 0.80 ~ 0.85 to (Xox)f ≧ 0.99 with RE = 45 %. Further study shows that, for (Xox)0 = 0.90 with a major impurity of MX or EB, DF results in (Xox)f = 0.99 with RE = 65 %. On the other hand, for (Xox)0 = 0.90 with a major impurity of PX, DF results in (Xox)f = 0.99 with RE = 35 % or (Xox)f = 0.98 with RE = 60 %.

碩士
國立成功大學
化學系碩博士班
98
In this research,the role of xylenol orange(XO) employed as a sensor molecule for Cu2+, Zn2+ ions was investigated. In XO aqueous solution,the absorption of visible light was significantly affected by the pH value. Therefore,we use TiO2 films as a buffer to avoid pH effects interfering the metal ion sensing.XO-TiO2 films were used to detect Cu2+ ions in the pH range of 3-5.5 and Zn2+ ions in the pH range of 4-5 with good buffering action and stable detection capabilities. The calibration curve plot of different Cu2+,Zn2+ ion concentration sensed by the XO-TiO2 films to ΔF(R) with a similar trend.It indicating that XO-TiO2 films have fixed detection mechanism for sensing metal ions and could be judged by the color change of the films with naked eyes.The naked-eye detection limit of XO-TiO2 films for the Cu2+ ion was 2.5×10-5 M(1.59 ppm) and for Zn2+ ion was 4×10-5 M(2.615 ppm).The detection limit of spectrum for Cu2+ was 7.5x10-6 M(0.476 ppm) and for Zn2+ was 1x10-5 M(0.654 ppm). Molecular dynamics simulations were employed to study the coordinated structure of Cu2+, Zn2+ ions in the XO aqueous solution. According to the structure in the simulation system,we analyzed the complex structure of XO molecules binding to Cu2+, Zn2+ ions, and we used the method of pair correlation function to reconfirm. Based on the result, we found that the Cu2+, Zn2+ ions might coordinated with the carboxylate group and sulfonic acid group of the XO molecule.

碩士
國立中興大學
化學工程學系所
98
Vapor-liquid equilibria at 333.15 K 343.15K and 353.15 K for seven binary mixtures of benzene + nonane, toluene + o-xylene, m-xylene + sulfolane, o-xylene + sulfolane, o-xylene + NMF, m-xylene + NMF and p-xylene + NMF have been obtained at pressures ranged from 0.01 to 101.3 kPa. The Wilson, NRTL and UNIQUAC activity coefficient models have been employed to correlate experimental data to find intermolecular parameters. The non-ideal behavior of the vapor phase has been considered by using the Peng-Robinson equation of state in calculating the vapor mole fraction. Liquid and vapor densities were measured by using two vibrating tube densitometers to determine liquid excess molar volumes. Six systems of benzene + nonane , m-xylene + sulfolane , o-xylene + sulfolane , o-xylene + NMF, m-xylene + NMF and p-xylene + NMF mixtures present large positive deviations from the ideal solution and belong to endothermic mixings because their excess Gibbs energies are positive. Temperature dependent intermolecular parameters in the three models were obtained in this study.

博士
長庚大學
化工與材料工程研究所
95
The demand for m-xylene is rising worldwide, because this compound is consumed primarily for the production of isophthalic acid (IPA), which is used increasingly as a copolymer in the manufacture of polyethylene terephthalate (PET) plastic bottles. The mixed xylenes produced mainly consist of p-xylene (PX), m-xylene (MX), o-xylene (OX) and ethylbenzene (EB). Due to their similar molecular structures, these isomers have close boiling points (e.g., MX=139.12℃, PX=138.37℃, OX=144.41℃ and EB=136.19℃). It is extremely difficult to separate MX economically. This research is focused on the separation of MX from the mixed xylenes. The study is divided into two parts. Firstly, direct-contact melt crystallization is applied to produce MX crystals from the mixed xylenes. The high pressure carbon dioxide is used as the coolant. The experiments show that the mixed xylenes can be purified from (XMX)0 = 0.700 to (XMX)f = 0.780 by direct-contact melt crystallization when the produced MX crystals are filtered without crystal washing. Secondly, a distillative crystallization technology, called distillative freezing (DF), is introduced to further purify MX from the mixed xylenes. Basically, DF is a distillative crystallization technology, which combines distillation and crystallization to produce pure crystals. DF is operated at triple point condition, in which the liquid mixture is simultaneously vaporized and solidified due to the three-phase equilibrium. A simulation method is proposed to provide essential information in operation of the DF process. The DF experiments show that, for (XMX)0 = 0.700~0.960, (XMX)f is close to (XMX)S while, for (XMX)0 = 0.980, (XMX)f is lower than (XMX)S. Further study shows that, for (XMX)0 = 0.960 with a major impurity of PX, DF results in (XMX)f =0.975. For (XMX)0 = 0.960 with a major impurity of OX or EB, DF results in (XMX)f =0.990~0.991. On the other hand, for (XMX)0 = 0.980 with a major impurity of PX, DF results in (XMX)f =0.990. For (XMX)0 = 0.980 with a major impurity of OX or EB, DF results in (XMX)f =0.993~0.994. Thus, it is more difficult to purify a feed of (XMX)0 = 0.960~0.980 with a major impurity of PX than a feed of (XMX)0 = 0.960~0.980 with a major impurity of OX or EB. In general, the experimental recovery rate of MX is close to the simulated recovery rate of MX.

碩士
長庚大學
化工與材料工程學系
101
Due to the close boiling points of p-xylene (PX) and m-xylene (MX), it is very difficult to separate them by distillation. Stripping crystallization (SC) is applied in this study to separate PX/MX mixtures. In principle, SC is operated at a triple-point condition, in which the liquid mixture is simultaneously vaporized and crystallized due to the three-phase equilibrium. Thus, SC is a distillative crystallization technology, which combines distillation and crystallization to produce pure crystals. By lowering temperature and reducing pressure during the operation, SC results in the formation of pure crystals, and liquid phase of vapor phase mixtures. A thermodynamic model is developed to simulate the three-phase equilibrium during the SC operation and to direct the batch SC experiments. The experiments show that SC can be successfully employed to purify PX from to with recovery ratio .

碩士
國立臺灣大學
企業管理碩士專班
102
Business Plan about starting up a Darts-theme cafe and restaurant with the objective of promote and raise awareness of darts sports in Malaysia Electronic darts machine had become a new trend in the world where received a very good response. However, similar to the olden days of snooker, its image is always associated with alcohol, smokings and night life which it always remain as a bar game. The author had carefully research about the industry and the consumer demand and hopefully this could promote the sports, improve the overall image of darts and create a vanue that everyone could enjoy the sports regardless of age and gender.

碩士
長庚大學
化學工程研究所
89
Abstract Xylenes have very broad applications and play important roles in the industries . Isomers produced in an isomerization reactor comprises p-Xylene、m-Xylene、o-Xylene、Ethylbenzene etc . Each of the isomers has it’s own field of application . In many applications high purity Xylenes are required . Separation purification of p-Xylene are accomplished by an adsorption process or a crystallization process；Separation purification of o-Xylene are accomplished by distillation process；Separation purification of m-Xylene are accomplished by an extraction process using HF+BF3 or a new adsorption process，called MX_SORBEX process . The costs of producing the Xylenes increase as the purities requires increase . In order to reduces producing cost increase the efficiencies come saver energy and attain high purities . We propose combing DF process with the conventional process and thereby optimumies the combing process . In the present thesis，we explain how to combine the conventional processes for producing p-Xylene、m-Xylene and o-Xylene with the Distillation Freezeing Process ( DF Process) that has been invented by professor Chen-Yen Cheng . We then compare the operating conditions of the conventional processes with the operating conditions of the combined processes . We are in the process of designing and constructing the equipment for the combined processes . We have completed the design of Wet Crystallization units、Soild Recycle DF units for p-Xylene、m-Xylene and o-Xylem purification . We have completed selection for cascade refrigeration systems；low pressure (＜0.001 torr) evacuation systems . We also conducted some preliminary test on a freeze drying unit and a modified Freeze Drying unit manufactured by KING MECH .

碩士
長庚大學
化工與材料工程學系
98
The study is by the numerical simulation way to separate binary mixtures of xylene(p-xylene/m-xylene) with the true-moving-bed adsorption separation system in vapor phase. Using Y-type zeolite as adsorbent and isopropylbenzene as desorbent. By the adsorbent on different adsorptive capacity of each component, and the mixtures with the adsorbent by way of counter-current in contact with the true-moving-bed for separation. The mathematical model considering axial dispersion and mass transfer resistance of the case, and multicomponent with the simplified Langmuir isotherm relationship established. The study will change the flow rate of feed, extract stream, and the fourth zone to simulate the concentration distribution of each zone and calculate the p-xylene in the extract stream and m-xylene in the raffinate stream of system performance. The simulation results show that in the pure extract region : reduction with m2, m3 remain fixed, the MX in the raffinate phase of separability increased ; with increased m3, m2 remain fixed, then the PX in the extract phase of recovery decreased. In the pure raffinate region : with increased m3, m2 remain fixed, the PX in the extract phase of separability increased ; reduction with m2, m3 remain fixed, then the MX in the raffinate phase of recovery decreased.

碩士
國立交通大學
生化工程研究所
97
According to previous study, benzene, and xylene are biodegradable in biofilter. In this study, biofiltration of benzene and xylene vapors has been studied in laboratory, with activated packing materials inoculated with appropriate microbial consortium. Various retention time (RT), i.e. 2, 1 and 0.5 min, were tested for xylene and benzene inlet concentration ranging from 0.6 to 2.0 g m-3. Both removal of benzene and xylene achieved the efficiency up to 90% at a retention time of 1 min. The maximum elimination capacity was 208 g m-3 h-1 and 248 g m-3 h-1 for benzene and xylene biofilter, respectively. Nitrogen source and pH effects were also been studied. When nitrogen source was not in benzene system, removal of benzene indeed decreased, where as obvious changed in xylene system. When the nitrogen source changed from (NH4)2SO4 to KNO3, removal of xylene slightly elevated from 79% to 83%. The pH 3 to 10 did not affect removal of xylene. However, reducing sugar increased and accumulation of nitrate when pH was declined. In benzene biofilter, the optimal removal pH was around 7.5~10.3. Removal of xylene was positive related with temperature in the range from 25 ~ 35 ℃。