published_or_final_version / Mechanical Engineering / Master / Master of Science in Engineering

In this project the link between species in solution and the solid state was considered. This is relevant due to the many applications in life where there is this interchange between solid and solution state, for example drug design, environmental metal speciation and the manufacture of materials that are in contact with solution (such as outdoor surface coatings, containers and so on). Complexation of two metal ions, namely cadmium(II) and bismuth(III), was studied. With bismuth showing so much promise in medicinal applications it was pertinent to investigate this interchange since the intake of medication is generally in the solid form which then converts to solution species as it dissolves in the body where it becomes active. For cadmium it is mainly the environmental concerns which we are faced with that call for the examination of speciation of complexes in solution, as well as their disposition upon precipitation or crystallization. A correlation was found between solution species and the complex that was isolated in the crystalline form with regards to pH for a number of metal-ligand species. We show how the results from solution experiments (achieved using direct current polarography) and those of crystalline complexes can complement each other when using species distribution diagrams as the intermediary. The distribution of species can be varied by changing the concentration and ligand-to-metal ratio at which the species distribution diagram is plotted. It is this characteristic which allows the solution and crystalline complexes – which are achieved using differing experimental conditions – to be correlated. The speciation diagram for a metal-ligand system, calculated using formation constants derived from solutions studies, was used in most instances to target specific species for their growth in the solid state. In some cases the solid state structure was used to confirm a suspected solution species, and in others the result was used to identify minor solution species which cannot be detected by the techniques used in determining formation constants. Further, we show that doing solution experiments at a range of temperatures can also aid in elucidating these minor species. The growth of crystalline species at low pH was important for this work because the pH titrations used for solution experiments were conducted from below pH 2 where the diffusion junction potential is large and changing. An in-situ witness ion was incorporated into the experiment to monitor the shifts due to the diffusion junction potential so that they could be compensated for. Additionally, for bismuth-ligand systems, hydrolysis and complexation with nitrates occurs in this same pH region. The formation constants and the species identified below pH 2 therefore do carry some uncertainty, so obtaining crystalline complexes of these species provides further confidence in their prediction in solution.

Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. / Microfiche copy available in Archives and Science. / Vita. / Includes bibliographical references. / Ph.D.

No description available.

Thesis (Ph. D.)--Drexel University, 2006. / Includes abstract and vita. Includes bibliographical references (leaves 166-174).

Thesis (Ph.D.)--McMaster University (Canada), 1990. / Source: Dissertation Abstracts International, Volume: 52-10, Section: B, page: 5510. Supervisors: D. A. Thompson; W. W. Smeltzer; J. A. Davies.

Thesis (M.S.) -- Mississippi State University. Dave C. Swalm School of Chemical Engineering. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 213-223).

Orientadores: Antonio José de Almeida Meirelles, Mariana Conceição Costa / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-24T10:06:55Z (GMT). No. of bitstreams: 1 Maximo_GuilhermeJose_D.pdf: 6364914 bytes, checksum: 716122d30b63141c35ee3d3c3305de17 (MD5) Previous issue date: 2014 / Resumo: Para o desenvolvimento de chocolates, manteigas, molhos para salada, cremes cosméticos, medicamentos ou biocombustíveis, assim como na otimização de processos de extração, refino, fracionamento, cristalização e produção de energia, os fenômenos de transição de fases dos sistemas lipídicos são temas, há muito tempo, de diversos trabalhos na literatura. O objetivo desses trabalhos tem sido avaliar como a composição dos produtos altera as suas propriedades físico-químicas e em especial aquelas relacionadas aos processos de fusão. De fato, alterações na temperatura exercem um grande impacto na estrutura cristalina da fase sólida dos sistemas graxos e, consequentemente, nas propriedades sensoriais e reológicas dos produtos. Essas alterações produzem comportamentos termodinâmicos tão variados que a determinação do equilíbrio de fases sólido-líquido desses sistemas representa um grande desafio. Não obstante, quanto maior a complexidade do sistema, menor é a compreensão do seu comportamento. Ou seja, apesar do grande número de trabalhos presentes na literatura envolvidos na investigação dos fenômenos de fusão de sistemas lipídicos, novos dados experimentais e abordagens teóricas para a modelagem dos diagramas são necessários para sua compreensão. Neste contexto, este trabalho teve dois objetivos principais. O primeiro relacionado à determinação e análise de diagramas de fases sólido-líquido de sistemas lipídicos binários de interesse para a indústria. O segundo foi desenvolver alternativas teóricas para aprimorar a representação dos diagramas de fases baseado em abordagens termodinâmicas clássicas. Portanto, onze sistemas binários compostos por triacilgliceróis, ácidos graxos e álcoois graxos foram avaliados. Esses sistemas são potenciais agentes de estruturação, formação de organogéis, produção e armazenamento de energia na indústria de alimentos, farmacêutica e de materiais. Os diagramas de equilíbrio sólido-líquido dessas misturas apresentaram comportamentos distintos, dependentes da formação de fases sólidas miscíveis ou imiscíveis e da não-idealidade do sistema. Além disso, foram estudados quatro sistemas formados a partir da reação ácido-base de Brønsted entre ácidos graxos e etanolaminas. Neste caso, a formação de líquidos iônicos próticos cristalinos com grande habilidade para auto-organização e comportamento não-Newtoniano singular podem atuar como auxiliares em diversas aplicações químicas e farmacêuticas. O problema imposto pela miscibilidade da fase sólida na construção dos diagramas de fases foi superado pela implementação de um algoritmo para a resolução de um sistema de equações não-lineares baseado nas equações fundamentais do equilíbrio sólido-líquido. O objetivo do algoritmo "Crystal-T" foi determinar a temperatura em que o primeiro e o último cristal se fundem durante o aquecimento do sistema. Para isso, a não-idealidade de ambas as fases líquida e sólida foi avaliada utilizando equações baseadas na energia de Gibbs em excesso, incluindo o método de contribuição de grupos UNIFAC, para o cálculo dos coeficientes de atividade. Considerando o aumento da produção mundial e do consumo de óleos e gorduras, este trabalho, a partir de demandas emergentes da indústria e da pesquisa científica, contribuiu na superação de alguns obstáculos relacionados à compreensão do equilíbrio de fases sólido-líquido de sistemas lipídicos para a engenharia de produtos e processos / Abstract: The phase transition phenomena of lipidic systems have long since been evaluated by several works in literature for developing chocolate, butters, dressings, spreads, cosmetic creams, medicines or biofuels as well as for optimizing processes such as extraction, refining, fractionation, crystallization or energy production. The aim of such works has been to answer how the products¿ composition can affect their physicochemical characteristics especially that related to the melting processes. In fact, changes in temperature highly impact the crystalline structure of fatty systems¿ solid phase and, consequently, in the sensorial and rheological properties of the products. These changes led to so many thermodynamic behaviors that the determination of the solid-liquid equilibrium of these systems can configure a particular challenge. However, the greater the complexity of the system the lower the understanding of its behavior. In other words, despite the number of works in literature involved in the investigation of the melting phenomena of lipidic systems, there is still a lack of experimental data and modeling approaches for their understanding. In this context, this work was conducted with two main goals. The first was focused on the measurement and comprehension of the solid-liquid equilibrium phase diagrams of lipidic binary systems of industrial interest. The second was aimed at the development of theoretical alternatives to improve the phase diagram description based on classical thermodynamic approaches. Thus, eleven binary systems composed by triacylglycerols, fatty alcohols and fatty acids were evaluated. Such mixtures are potential structuring, organogelating and energy storing agents for food, pharmaceutical and materials industry. The solid-liquid phase diagrams of these mixtures presented distinct behaviors depending on the formation of immiscible or miscible solid phases and the non-ideality of the system. Also, four systems built through a Brønsted acid-base reaction between fatty acids and ethanolamines were also evaluated. In this case, the formation of protic ionic liquid crystals with high self-assembling ability and marked non-Newtonian behavior are promising for pharmaceutical and chemical applications. The problem imposed by the partial miscibility of the solid phase in the construction of the phase diagrams was overtaken by the implementation of an algorithm based on the resolution of a non-linear equations system built by the solid-liquid equilibrium fundamental equations. The "Crystal-T" algorithm was aimed at the determination of the temperature at which the first and last crystal melts during the heating process. For this, the non-ideality of both liquid and solid phases was evaluated using excess Gibbs energy equations, including the group-contribution UNIFAC model, for the calculation of the activity coefficients. Taking into account the growing increase of the world production and consumption of fat and oils, this work, from industrial and academic emerging demands, contributed to overtake some barriers on the understanding of the solid-liquid phase equilibrium of lipidic mixtures for products and process engineering / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos