Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 255-263). Available also in a digital version from Dissertation Abstracts.

Orientadores: Rubens Maciel Filho, Maria Regina Wolf Maciel / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-09T05:07:10Z (GMT). No. of bitstreams: 1 Ambrogi_LuizGustavo_M.pdf: 1521602 bytes, checksum: 8777faa756b62d452583b2eb62dd629a (MD5) Previous issue date: 2007 / Resumo: Para a síntese do acrilato de etila, foi desenvolvido um modelo contínuo bidimensional estacionário para um reator tubular, considerando transferência de calor e massa por dispersão radial e convecção axial. Foi assumido o modelo pseudo-homogêneo sendo do tipo ¿plug-flow¿, o qual se mostrou adequado para as condições de escoamento utilizadas. Todos os elementos necessários à modelagem detalhada do processo foram estabelecidos, incluindo informações experimentais, bem como as correlações para cálculo das propriedades físicas dos componentes puros, os métodos de cálculo respectivos à mistura, as correlações para estimativa dos parâmetros de transferência de massa e energia e a perda de carga. O modelo foi desenvolvido para trabalhar com diferentes métodos numéricos. Uma adimensionalização das variáveis foi realizada antes da discretização das equações diferenciais parciais pelo Método de Colocação Ortogonal. A solução numérica é baseada na implementação do Método das Linhas, o qual é uma combinação de um método de colocação ortogonal na dimensão radial e uma integração axial pelo método de Runge- Kutta de 4 ª ordem. Um método baseado na Quadratura de Gaus-Jacobi foi utilizado para o cálculo das médias das propriedades físicas na radial para cada intervalo de integração. O comportamento do reator é investigado em função de sua sensibilidade a um grupo de parâmetros de projeto e operação. Este software, que na verdade é uma planta virtual, foi utilizado para representar a produção do acrilato de etila em escala industrial em um reator multitubular. O catalisador utilizado foi ácido sulfúrico e as informações sobre a cinética foram suficientes para abordar várias operações compatíveis com as condições industriais. A reação é endotérmica, homogênea, possui uma cinética de segunda ordem e ocorre na fase líquida. A temperatura de reação utilizada foi em torno de 80 ºC, e o fluido de aquecimento utilizado foi o Dowterm A. Para etapa de separação utilizou-se um software comercial, no caso o Aspen Plus. Esta etapa compreendeu primeiramente a caracterização termodinâmica da mistura reacional, e em seguida, a simulação dos principais equipamentos utilizados na separação, visando a otimização do processo. O Acrilato de etila é um éster produzido a partir do ácido acrílico e do etanol. Ésteres acrílicos como este, são mundialmente utilizados para a produção de polímeros, os quais por sua vez, são utilizados principalmente na indústria de tintas e vernizes, adesivos, couro, papel, e tecidos. O que motivou este trabalho, foram os recentes avanços no desenvolvimento de uma rota bioquímica para a síntese do ácido acrílico, utilizando a cana de açúcar como matéria prima. Hoje o ácido acrílico é produzido pela oxidação do propeno, ou seja, uma rota petroquímica. Como o etanol também é produzido no Brasil a partir da cana de açúcar, com um preço muito competitivo comparado à via petroquímica, é possível desenvolver uma ¿rota verde¿, a qual pelos resultados encontrados, é interessante tanto do ponto de vista financeiro quanto ambiental / Abstract: For the synthesis of ethyl acrylate, a continuous bi-dimensional steady-state model for a tubular reactor is developed, considering heat and mass transfer by radial dispersion and axial convection. The model is pseudo-homogeneous and is assumed a plug flow type, which it quite reasonable for the used flow conditions. All the elements necessary to the detailed process modeling were established, including experimental information as well as the correlations to calculate the pure-component physical properties, the respective mixture properties calculations methods, the correlations to estimate heat and mass transfer parameters and pressure drop. The model is built and rearranged to be solved for different numerical methods. An adimensionalization of the variables was carried out before the discretization of the partial differential equations by Orthogonal Collocation method. The numerical solution is based on the method of lines implementation, which is a combination of an orthogonal collocation method in the radial dimension and an axial integration by an explicit 4th order Runge-Kutta method. A Gauss-Jacobi quadrature based method for the radial mean physical properties calculations is used as an internal procedure for each integration interval. This software, in fact a virtual plant, was used to represent the industrial scale production in a multitubular reactor. The catalyst used was sulfuric acid and the information about kinetic was available to cover a broad range of operations compatible with industrial conditions. The kinetic is of second order, homogeneous and the reaction is endothermic and it takes place in the liquid phase. The reactor temperature was about 80 ºC, and Dowtherm A was used as heater fluid. The commercial software Aspen Plus, was used for the separation step. This step includes firstly a thermodynamic characterization of reaction mixture, and after, the simulation of the major equipments used in the separation step, aiming the process optimization. Ethyl acrylate is an ester produced from acrylic acid and ethyl alcohol. Acrylic esters such this, are worldwide used, primarily for polymers production, mainly for coatings, paints, adhesives, and binders for leather, paper, and textiles. The motivation of this work, was the recent advances in the development of biochemical route for the synthesis of acrylic acid by the sugar cane. Today the acrylic acid is produced by the propene oxidation, or a petrochemical route. As the ethyl alcohol is already produced in Brazil by the sugar cane, in a very competitive price compared to petrochemical via, it is possible to develop a ¿green route¿, which by the results found, is both interesting in a financial and environmental point of view / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Magnetic particles have attracted increasing attention in fields ranging from separation processes to electromagnetic information storage an medical application. Various approaches for their synthesis have been developed and studied to satisfy the criteria of production. Improvement and optimization of size, stability, and functionality is of vital importance in biological applications. The main aspect of project, initially, was to study the application of aqueous functionalized magnetic nanoparticles coupled with high gradient magnetic separation technique for the removal of trace residue of organic contaminants from drinking water. However, the importance of synthesizing stable ferrofluid for this purpose became clear later and took precedence over the initial objective. Different approaches were adopted, such as the incorporation of poly(ethylene glycol) methacrylate, ethylenediamine, and chitosan, to enhance the stability of magnetic particles. However, these surface modifications had unfavorable effect on the stability of initial particles. In accord with the initial objective of the project, the possibility of utilization of β-cyclodextrin, as organic pollutant entrapment agent, was investigated in preliminary studies conducted on its interaction with a model compound, procaine hydrochloride. The outcomes of these experiments suggest its potential as a biocompatible removal agent for the elimination of organic pollutant in drinking water system, or other applications that require selective separation of organic compounds.

Magnetic particles have attracted increasing attention in fields ranging from separation processes to electromagnetic information storage an medical application. Various approaches for their synthesis have been developed and studied to satisfy the criteria of production. Improvement and optimization of size, stability, and functionality is of vital importance in biological applications. The main aspect of project, initially, was to study the application of aqueous functionalized magnetic nanoparticles coupled with high gradient magnetic separation technique for the removal of trace residue of organic contaminants from drinking water. However, the importance of synthesizing stable ferrofluid for this purpose became clear later and took precedence over the initial objective. Different approaches were adopted, such as the incorporation of poly(ethylene glycol) methacrylate, ethylenediamine, and chitosan, to enhance the stability of magnetic particles. However, these surface modifications had unfavorable effect on the stability of initial particles. In accord with the initial objective of the project, the possibility of utilization of β-cyclodextrin, as organic pollutant entrapment agent, was investigated in preliminary studies conducted on its interaction with a model compound, procaine hydrochloride. The outcomes of these experiments suggest its potential as a biocompatible removal agent for the elimination of organic pollutant in drinking water system, or other applications that require selective separation of organic compounds.

L'acrylate d'éthyle est synthétisé par l'estérification catalytique de l'acide acrylique et de l'éthanol. La réaction s'écrit : CH2=CH-COOH + C2H5OH D CH2=CH-COOC2H5 + H2O Comme cette réaction est équilibrée, l'élimination de l'eau produit par la réaction permet de déplacer la réaction, donc d'augmenter le taux de conversion de l'acide acrylique et la productivité en acrylate d'éthyle. La pervaporation est une technique de séparation membranaire, qui est potentiellement intéressante pour la déshydratation de mélanges organiques. Dans ce travail, nous avons étudié le procédé industriel de l'estérification de l'acrylate d'éthyle qui est continu. C'est la première fois que la pervaporation d'un mélange complexe contenant des dérivés acryliques polymérisables est étudiée. Tout d'abord le procédé continu d'estérification a été simulé sur Aspen Plus. Une analyse du schéma de procédé a permis d'identifier deux scénarii d'amélioration des performances énergétiques par pervaporation. Dans le scénario le plus favorable, la pervaporation permet de réduire de 25% la consommation d'énergie ou d'augmenter de 25% la production. Dans la deuxième partie de notre étude, des membranes commerciales ont été testées pour déshydrater des mélanges représentatifs du milieu d'estérification. Les membranes testées ont montrées de bonnes performances de séparation (flux et sélectivité élevées) et de bonnes résistances chimiques. La faisabilité de l'intégration de la pervaporation au procédé est donc prouvée / Ethyl acrylate is synthesized by the catalytic esterification of acrylic acid and ethanol. The reaction can be described as: CH2=CH-COOH + C2H5OH D CH2=CH-COOC2H5 + H2O Since this reaction is reversible, the removal of the water helps shifting the reaction to the right side, thus increasing the conversion of acrylic acid to ethyl acrylate. Pervaporation is a membrane separation technique which is helpful for the dehydration of organic mixtures. In this work, we studied the industrial process for the esterification of ethyl acrylate which is continuous. To our knowledge this is the first time that the pervaporation of a mixture containing polymerizable acrylic derivatives is studied. Firstly, the continuous esterification process was simulated on Aspen Plus. An analysis of the flowsheet diagram has identified two scenarios for improving energy performance through implementing dehydration pervaporation. In the most favorable scenario, the pervaporation can reduce 25% energy consumption or increase 25% ethyl acrylate production. In the second part of our study, commercial membranes were tested for dehydrating mixtures which are representative of esterification reaction. The tested membranes offered good separation performance (high flux and selectivity) and high chemical resistance. The feasibility of the hybrid process is thus proven

No description available.

There is growing interest in the development of biomimetic matrices that are simultaneously cell-friendly, allow rapid vascularization, exhibit enough mechanical integrity to be comfortably handled and resist mechanical stresses when implanted in the site of interest. Meeting all these requirements with a single component material has proved to be very challenging. The hypothesis underlying this work was that hybrid materials obtained by combining scaffolds with bioactive hydrogels would result in a synergy of their best properties: a construct with good mechanical properties, easily handled and stable thanks to the scaffold; but also, because of the gel, cell-friendly and with enhanced oxygen and nutrients diffusion, and promoter of cell colonization. Moreover, such a composite material would also be useful as a controlled release system because of the gel’s incorporation. Poly (ethyl acrylate) (PEA) scaffolds prepared with two different morphologies were envisaged to provide the mechanical integrity to the system. Both types of scaffolds were physicochemically characterized and the effect of the scaffolds production process on the PEA properties was examined. The scaffolds preparation methods affected the PEA properties; nevertheless, the modifications induced were not detrimental for the PEA biological performance. Two different bioactive gels were studied as fillers of the scaffolds’ pores: hyaluronan (HA), which is a natural polysaccharide, and a synthetic self-assembling peptide, RAD16-I. HA is ubiquitously present in the body and its degradation products have been reported to be angiogenic. RAD16-I is a synthetic polypeptide that mimics the extracellular matrix providing a favourable substrate for cell growth and proliferation. Given the hydrophobic nature of poly(ethyl acrylate), the combination of PEA scaffolds with aqueous gels raised a number of problems regarding the methods to combine such different elements, the ways to gel them inside the pores, and the procedures to seed cells in the new composite materials. Different alternatives to solve these questions were thoroughly studied and yielded protocols to reliably obtain these complex structures and their biohybrids. An extensive physico-chemical characterization of the components’ interaction and the combined systems was undertaken. As these materials were intended for cardiac tissue engineering applications, the mechanical properties and the effect of the fatigue on them were studied. The different composite systems here developed were homogeneously filled or coated with the hydrogels, were easy to manipulate, and displayed appropriate mechanical properties. Interestingly, these materials exhibited a very good performance under fatigue. The use of the composite systems as a controlled release device was based on the possibility of incorporating active soluble molecules in the hydrogel within the pores. A release study of bovine serum albumin (BSA), intended as a model protein, was performed, which served as a proof of concept. The biological performance of the hybrid scaffolds was first evaluated with fibroblasts to discard the materials cytotoxicity and to optimize the cell seeding procedure. Subsequently, human umbilical vein endothelial cells (HUVECs) cultures were performed for their interest in angiogenic and vascularization processes. Finally, co-cultures of HUVECs with adipose-tissue derived mesenchymal cells (MSCs) were carried out. These last cells are believed to play an important role for clinical regenerative medicine, and their cross-talk with the endothelial cells enhances the viability and phenotypic development of HUVECs. Through the different experiments undertaken, hybrid scaffolds exceeded the outcome achieved by bare PEA scaffolds. / Arnal Pastor, MP. (2014). New scaffolding materials for the regeneration of infarcted myocardium [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/46129 / TESIS / Premios Extraordinarios de tesis doctorales

Livscykelanalys är en metod som utformades och utvecklades för att kvantifiera miljöpåverkan från produkter och tjänster för mer än trettio år sedan. Sedan dess har den kontinuerligt förbättrats och blivit mer och mer robust. Som tillverkare av kemiska produkter och monomerer använder Arkema livscykelanalys för att mäta sina produkters miljöpåverkan. Detta görs för att förstå enskilda produkters fotavtryck samt företagets övergripande miljöpåverkan. För att göra detta används ISO-normerna 14040 och 14044. Dessa normer anger generiska ramar för LCA-beräkningar men är inte specifika för den kemiska industrin. Med tanke på att metodologiska svårigheter kan uppstå inom den kemiska sektorn har många riktlinjer och rekommendationer publicerats på senare tid. I denna uppsats studeras och jämförs några av dessa riktlinjer. Tillämpningen av dessa metoder utförs på två produkter inom Arkemas portfölj: akrylsyra och etylakrylat, som är byggstenar för många polymerer. Resultaten av utvärderingen visar på områden där förbättringar kan göras. För de studerade produkterna är råvarorna de största bidragande orsakerna. Därför kan det vara fördelaktigt att övergå från petroleumbaserade material till biobaserade. Att välja den minst miljöpåverkande produktionsvägen är också ett sätt att aktivt minska produkternas koldioxidavtryck. / Life Cycle Assessment is a methodology that has been designed and developed to quantify the environmental impacts of products and services more than thirty years ago. Since then, it has been in continuous improvement and becomes more and more robust. As a producer of chemical products and monomers, Arkema uses Life Cycle Assessment to measure the environmental impact of its products. This is done to understand the footprints of individual products as well as the company's overall environmental impact. To do so, the ISO norms 14040 and 14044 are used. These norms set generic frames for LCA calculation but are not specific to the chemical industry. Considering that methodological difficulties can arise in the chemical sector, many guidelines and recommendations are being published recently. In this thesis, some of those guidelines are studied and compared. The application of these methodologies is performed on two products within Arkema’s portfolio: acrylic acid and ethyl acrylate, which are building blocks for many polymers. The results of the assessment reveal areas where improvements can be made. For the products studied, the main contributors are the raw materials. Therefore, transitioning from petroleum-based materials to biobased ones could be beneficial. Additionally, selecting the least impactful production route is also a way to actively reduce the carbon footprint of the products.