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Submitted in fulfillment of the academic requirements for the degree of Master of Engineering in Engineering, Durban University of Technology, Durban, South Africa, 2018. / Many separation processes in the chemical and petrochemical industries are energy intensive, and unfortunately, involve a range of solvents that are environmentally harmful and destructive. Alternative, sustainable separation techniques are desired to replace these conventional methods used in the separation of azeotropic as well as close-boiling mixtures, with the intention of reducing energy costs and adverse impact on the environment. In the present study, a new class of solvents called deep eutectic solvents (DESs) of Type III were investigated as alternatives to conventional solvents currently employed in separation processes. DESs are classified as ‘green’ solvents because of a range of favourable properties including lower cost, desirable solubility properties and reduced environmental impact (Abbott et al., 2003b; Smith et al., 2014). The infinite dilution activity coefficients (IDACs) values of 24 solutes – including alk-1-anes, alk-1-enes, alk-1-ynes, cycloalkanes, alkanols, alkylbenzenes, heterocyclics, esters, and ketones – were measured at 313.15, 323.15, 333.15 and 343.15 K by gas-liquid chromatography (GLC) in DESs. The four investigated DESs were as follows: 1) Tetramethylammonium chloride + Glycerol (DES1); 2) Tetramethylammonium chloride + Ethylene Glycerol (DES2); 3) Tetramethylammonium chloride + 1,6 Hexanediol (DES3); and 4) Tetrapropylammonium bromide + 1,6 Hexanediol (DES4). This work focused on the performance of DESs as extractive solvents for selected azeotropic and close-boiling binary mixtures. The two key performance criteria for these extractive solvents – selectivity and capacity – were determined from experimental infinite dilution activity coefficients (IDACs) of various solutes. The effect of solute molecular structure on IDAC values was investigated. Moreover, the effect of varying the hydrogen bond donors (HBDs) in DESs on IDAC values was examined. Partial excess molar enthalpies at infinite dilution were determined from the experimental IDAC data. Moreover, common industrial separation problems were selected to investigate DES potential to separate various mixtures by determining selectivity and capacity at infinite dilution. The results obtained in this study indicate that the use of a long carbon chain HBDs greatly decreases miscibility of DESs with organic solutes. For systems such as n-heptane - toluene, acetone - ethanol, cyclohexane - benzene and n-hexane - benzene systems, DES4 was the best solvent regarding the separation performance index. However, further investigation for DES4 by measurements of vapour-liquid equilibria (VLE) and liquid-liquid equilibria (LLE) data is suggested, as these data would provide additional pertinent information regarding the separation of such mixtures using DES4. The data produced from this study can be used to extend the applicability range of predictive models such as Universal Quasi- Chemical Functional Group Activity Coefficients (UNIFAC) and modified UNIFAC (Do) which are already incorporated in some chemical engineering process simulators. / M

The study introduces and demonstrates the viability of the continuous flow reactor (CFR) system for the production of bio-crude oil (BCO) from wet microalgae. Preliminary experiments conducted in the CFR system in hot compressed water (HCW) were successful in converting wet microalgae into liquid BCO. However, the synthesis and aggregation of high boiling point (HBP) components of BCO and the accumulation of char in the tubular piping of CFR system were identified as the limiting factor to the viability of the system. The aggregation of HBP components and the accumulation of char result to system blockage which prevents the continuous flow of the liquefaction product mixture in the CFR system. Inhibiting the reactions leading to the formation of HBP components and char will improve the performance of the CFR system. Therefore, the study seeks to incorporate co-solvents in the liquefaction reaction media in an attempt to inhibit or minimize the prevalence of HBP components of BCO. As such, different co-solvents were screened for their influence on improving the quality of BCO with respect to its boiling point profile (BPP), initial and final boiling point, as well as the amount of char recovered from each experiment. Only one co-solvent was chosen for further exploration in the CFR system. Batch liquefaction reactor’s (BLR) made up of stainless steel were used to carry out the co-solvent screening experiments. These experiments were carried out at a constant temperature (280 °C), pressure (75 bar), and co-solvent concentration (10 wt.%), at varying residence times. Solvent extraction with dichloromethane (DCM) was performed on the liquefaction product mixture to separate the products, viz. BCO, char and water soluble components. The extracted BCO was analysed through simulated distillation (SimDis) to obtain the BPP. The BPP properties of the BCO samples, from different liquefaction media, and the amount of char recovered were highly influenced by the addition of a co-solvent. The final boiling point (FBP) of tetralin, heptane, and n-octanol BCO products were significantly reduced to below 500 °C for all tested residence times except at 20 minutes. The residence time also proved to be influential in the processing of wet microalgae. n-Octanol was selected as the optimal performing co-solvent and was used for the continuous liquefaction of wet microalgae in the CFR system. The CFR system was modified by adding a co-solvent feed line into the continuous system since n-octanol was insoluble in water. The n-octanol pump was set at different flow rates, 0.2, 0.3, and 0.4 g/min, which resulted in a concentration of about 10 wt.% in the reactor feed. The concentration of n-octanol had a significant influence on the BPP of BCO components. The FBP’s were reduced with an increase in n-octanol concentration. The initial boiling point (IBP) of n-octanol BCO was increased to just above 100 °C which was required for the stability of the BCO product. The components of BCO were identified by GCMS. n-Octanol also proved to affect the composition of the BCO with respect to its components. HCW BCO components were significantly different from those identified from n-octanol BCO. A second co-solvent (tetralin) was used to prove whether the difference on the components of BCO was affected by n-octanol. The results proved that indeed the addition of different solvents in liquefaction reaction media favours the formation of different components. The amount of char formed was also reduced when using a co-solvent. A decrease in the oxygen/nitrogen compounds was also observed in the presence of a co-solvent, thus improving BCO properties.

Orientador: Mario Roberto Vizioli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-07-27T11:24:17Z (GMT). No. of bitstreams: 1 Ramos_MabelPhilipps_M.pdf: 4905002 bytes, checksum: f8a62f9d47dd3b1915a675f55703713f (MD5) Previous issue date: 2000 / Resumo: O retratamento é a primeira opção para os casos de insucesso da terapia endodôntica. Para que possa ser realizado, é preciso remover o material obturador pré-existente no canal radicular. O uso de solventes facilita este procedimento, além de evitar a ocorrência de acidentes. Um dos requisitos desejáveis é de não serem agressivos aos tecidos periapicais. Sendo assim, a proposta deste estudo foi de avaliar o potencial irritante destes solventes e comparar seus efeitos sobre o tecido subcutâneo de ratos. Para isto, 12 animais foram utilizados, recebendo quatro tubos de polietileno. Três preenchidos com Fibrinol embebido em cada uma das substâncias-teste, ou seja, clorofórmio, eucaliptol e óleo de laranja e um tubo preenchido apenas com Fibrinol que serviu de controle. Os animais foram sacrificados após 4, 7, 11 e 15 dias, com remoção dos tecidos dorsais que continham os tubos. Após processamento laboratorial das peças incluídas em glicol metracrilato, foram realizados cortes de 3 m m de espessura, corados com hematoxilina e eosina e analisados em microscopia óptica. Os resultados obtidos demonstraram que o óleo de laranja foi o solvente menos irritante. Subjetivamente não foi encontrada diferença entre o poder irritante do eucaliptol e do clorofórmio. Sendo assim, acreditamos que o óleo de laranja possa ser a alternativa mais adequada para a desintegração do material obturador durante o retratamento endodôntico / Abstract: Re-treatment is the first option in case of failure of the endodontic therapy. To enable this process, it is essential to remove the pre-existing filling material of the root canal. The use of solvents facilitates this procedure and helps to avoid accidents. One of the properties required from these solvents is non-aggression to periapical tissues. The aim of this study is, therefore, to evaluate the harmful potential of these solvents and compare their effect on subcutaneous tissue of rats. Twelve rats were used to carry out the experiment. Four polyethylene tubes were implanted in each animal, and these tubes were filled with Fibrinol imbibed in one of the test-substances, which were chloroform, eucalyptol, and orange oil. The fourth tube was filled only with Fibrinol and was used as a control. Animals were killed 4, 7, 11 and 15 days after implant procedures, and dorsal tissues contained in the implants were removed. After laboratory processing of the specimens, which were immersed in metacrylate glycol, three 3 mm-wide sections were made. These sections were stained with hematoxylin and eosin, and analyzed through microscopy. The results showed that the least harmful solvent was the orange oil. Subjectively, no difference was found between the harmful potential of eucalyptol and chloroform. We therefore believe that the orange oil may be the most appropriate alternative for disintegration of filling material during endodontic re-treatment / Mestrado / Mestre em Radiologia Odontológica

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The philosophy of green chemistry has seen much development in the past decade. The use of environmentally benign solvents is amongst the areas of green chemistry that have received the most attention. In this context, imidazolium ionic liquids have been widely reported to offer high product yields, fast reaction rates, excellent selectivity and generally mild working conditions, when used as reaction media. In addition, concerns about costs of solvents and the long-term environmental impact that can potentially result when solvents are discarded after their use have led to focused investigations into solvent-free procedures, as reported in recent literature. We have set out to explore the extent to which these advantages could be realized within our research. Non-volatile, non-flammable imidazolium ionic liquids [bmim][I], [bmim][BF4] and [bmim][PF6] were used as green solvents in ferrocene chemistry. Ferrocenoate esters were synthesised efficiently by the respective DCC/DMAP-promoted reactions of ferrocenecarboxylic acid and substituted benzoic acids or, alternatively, the DMAP-promoted reactions of ferrocenoyl fluoride with a range of substituted phenols in [bmim][BF4] and [bmim][PF6]. High yields and short reaction times were achieved. In addition, the ionic liquid was reused several times without a reduction in product yields. Under solvent-free conditions, DCC/DMAP-promoted reactions provided high yields within 3 min of reaction. The possible rearrangement of one of the intermediates in these reactions was modelled theoretically using density function theory (DFT) at the B3LYP/6-31G* level of approximation. Catalyst-free esterification was achieved by the application of microwave radiation to the reaction of ferrocenoyl fluoride and a range of substituted phenols. All the reactions were complete after 1 min of irradiation and products were isolated in high yield. DPAT, HfCl4, Sc(OTf)3 and Al(OTf)3 were screened as catalysts for esterification in [bmim][BF4] and under solvent-free conditions at various temperatures. All attempts at esterification of ferrocenecarboxylic acid with alcohols and phenols were unsuccessful. The Suzuki cross-coupling reaction was carried out in [bmim][BF4]. The isolated yields are, however, poor and suffer from poor reproducibility with different batches of [bmim][BF4] used.

Orientador: Walace Alves de Oliveira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-26T13:24:33Z (GMT). No. of bitstreams: 1 Lima_JoaquimMatiasBittencourt_M.pdf: 2410483 bytes, checksum: eb7f40c8e6feac1eec3059a9a6ccfb12 (MD5) Previous issue date: 1979 / Resumo: Foi desenvolvido o estudo de um padrão ebuliométrico para solventes não aquosos. Benzila foi escolhido como soluto e benzeno como padrão. Foram medidas as elevações na temperatura de ebulição do benzeno, causadas pela adição de benzila, e os coeficientes osmótico e de atividade puderam ser avaliados. A aparelhagem e o método operacional são descritos. São discutidos os diversos tipos de sensores de temperatura que podem ser utilizados e apresentadas as razões pelas quais foram escolhidos termístores para tal fim. Os termistores foram calibrados, e com base em calibração anterior, foram avaliadas as alterações nas suas características. São propostas equações para que, por método analítico, sejam medidas as elevações de temperatura, o coeficiente de atividade e o coeficiente osmótico. Foi discutido o desvio da idealidade apresentado pelo padrão. É proposto um método comparativo para determinação de constante de equilíbrio, permitindo com que, utilizando o padrão ebuliométrico, fosse determinada a constante de dimerização do ácido benzóico em benzeno, cujo resultado, comparado com dados oriundos da literatura, apresentou boa concordância / Abstract: The behavior of benzil as an ebulliometric standard for non-aqueous solvents was studied. Boiling-temperature elevations due to addition of benzil in benzene were measured and osmotic and activity coefficients were calculated. The apparatus and procedure are discussed. Several types of temperature sensors are mentioned and thermistors were chosen to be used. The thermistors were calibrated and the changes in their parameters were evaluated based on results of previous calibration. Equations are given which permit the calculation of boiling-temperature elevation of benzene solutions as well as osmotic and activity coefficients. The departure from ideal behavior is discussed. A comparative method for the ebulliometric determination of equilibrium constants is proposed. The dimerization constant of benzoic acid in benzene was determined by this method and the results are in good agreement with literature values / Mestrado / Quimica Organica / Mestre em Química

Orientador: Americo Bortolazzo Correr / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-26T22:34:56Z (GMT). No. of bitstreams: 1 Araujo_TatianyGabrielleFreire_D.pdf: 2672056 bytes, checksum: dabae7d2ba0ca53d49bf01816863660a (MD5) Previous issue date: 2015 / Resumo: O objetivo neste estudo foi avaliar o efeito da adição dos solventes dimetil sulfóxico (DMSO) e tetrahidrofurano (THF) em propriedades físico-químicas de infiltrantes experimentais. Foram preparadas duas blendas resinosas, uma composta por 75%p de TEGDMA (T) e 25%p UDMA (U) e outra por 75%p de T e 25%p de BISEMA (B). Em um grupo de cada mistura não foi adicionado solvente. Os demais grupos foram formulados pela adição dos solventes DMSO ou o THF nas concentrações de 0,5% e 5%. No total foram obtidos 10 infiltrantes experimentais. Icon® foi utilizado como controle. Este estudo foi separado em 2 capítulos. No capitulo 1 o objetivo foi avaliar a influência dos solventes DMSO e THF no ângulo de contato, dureza Knoop em lesões artificiais de cárie infiltradas e a capacidade de penetração dos infiltrantes experimentais em microscópio confocal de varredura a laser. Os dados do ângulo de contato foram submetidos à analise de variância um fator e teste de Tukey, e os de dureza Knoop avaliados por analise de variância dois fatores e teste de Tukey (?=0,05). Os resultados mostraram que o Icon apresentou o menor ângulo de contato. Dentre os infiltrantes experimentais, o menor ângulo de contato foi apresentado pela mistura T + U + 5% DMSO, significativamente menor que as misturas T + U, T + U + 0,5% DMSO, T + U + 5% THF, T + B + 0,5% DMSO e T + B + 0,5% THF. Os resultados de microscopia confocal de varredura a laser mostraram que os infiltrantes apresentaram boa penetração nas lesões artificiais de cárie exceto os grupos T + B, T + B + 0,5% DMSO e T + B + 0,5% THF. As lesões infiltradas por Icon apresentaram dureza significativamente maior que dos outros materiais, exceto T + U + 0,5% DMSO (252,4) e T + U + 5% THF (239,1). Concluiu-se que o Icon apresentou os melhores resultados dentre os materiais avaliados, com menor ângulo de contato, maior dureza e boa penetração. Dentre os materiais experimentais, a incorporação de 5% de DMSO na mistura de U reduziu o ângulo de contato e apresentou dureza semelhante à infiltrada por Icon. No capitulo 2 foi verificada a influência dos solventes DMSO e THF nos infiltrantes experimentais no grau de conversão (GC) (n = 3), resistência coesiva à tração (RT) (n = 10), resistência de união a microtração (RU) (n = 10), resistência a flexão (RF) (n = 10) e módulo de elasticidade (ME) (n = 10). Os dados foram submetidos à ANOVA um fator e teste de Tukey (? = 0,05). Foi verificado que o GC dos infiltrantes com U foi significativamente maior que dos demais infiltrantes. Os infiltrantes experimentais sem solvente apresentaram RF significativamente maior que Icon e que os infiltrantes com solvente. Os infiltrantes com 5% de DMSO apresentaram RU significativamente menor que os demais; Icon apresentou RU significativamente maior que os demais infiltrantes. A RT de Icon foi significativamente maior que dos infiltrantes experimentais. Conclui-se que os solventes DMSO e THF não melhoraram a resistência de união e prejudicaram as propriedades mecânicas dos infiltrantes experimentais. Dentre os solventes, o THF na concentração de 0,5% apresentou menos efeitos deletérios nas propriedades mecânicas dos infiltrantes experimentais. Como conclusão geral, pode ser verificado que o infiltrante Icon apresentou os melhores resultados. Dentre os infiltrantes experimentais, o melhor desempenho foi obtido com a mistura T e U. A adição 0,5% do solvente DMSO na mistura T e U não reduziu o ângulo de contato e reduziu as propriedades mecânicas dos infiltrantes, mas produziu resistência de união e dureza da lesão infiltrada semelhante ao infiltrante Icon / Abstract: The aim of this study was to evaluate the effect of alternative solvents addition dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF) in the chemical-physical properties of experimental infiltrants. Were prepared 2 blends: (1) 75wt% TEGDMA (T) + 25 wt% UDMA (U), (2) 75wt% T + 25wt% BISEMA (B). From each blend were added the solvents DMSO or THF in concentrations of 0.5wt% and 5wt%, totaling 10 experimental groups. Icon® was used as control. This study was divided in 2 chapters. In chapter 1 the aim was to evaluate the influence of alternative solvents (DMSO and THF) in the contact angle, Knoop hardness of artificial caries lesions infiltrated, and the capability of penetration of the experimental infiltrants. Data were analyzed by ANOVA one-way (contact angle) and two-way (Knoop hardness) and Tukey's test (?=0.05). The results showed that Icon presented the lowest contact angle. Analyzing the experimental infiltrants, T + U + 5% DMSO showed the lowest contact angle. The confocal microscopy analysis showed that the infiltrants presented satisfactory penetration into the caries-like lesions except the groups T + B, T + B + 0.5% DMSO and T + B + 0.5% THF. Lesions infiltrated with Icon exhibited hardness values significantly higher than all the experimental groups, except to T + U + 0,5% DMSO (252.4) e T + U + 5% THF (239.1). It is possible to conclude that Icon showed the best results for the tested properties. In chapter 2 was analyzed the influence of the addition of DMSO and THF solvents in experimental infiltrants in relation to degree of conversion (n=3), ultimate tensile strength (n=10), microtensile bond strength (n=10), flexural strength (n=10) and elastic modulus (n=10). Data were submitted to one-way ANOVA and Tukey's test (?=0.05). Infiltrants containing U obtained the highest degree of conversion values. The solvents-free experimental infiltrants showed the highest values of flexural strength. In relation to microtensile bond strength results, the groups with 5% DMSO presented the lowest results and Icon the highest ones. Icon group obtained the highest results of UTS. It is possible to conclude that the addition of solvents DMSO and THF did not improve the bond strength and affected negatively mechanical properties of the experimental infiltrants. THF solvent 0,5% showed less deleterious effects in mechanical properties of experimental infiltrants. Overall, Icon xi obtained the best results. Among the experimental infiltrants, the best performance was obtained by the association of T and U. The addition of 0.5% of DMSO in the blend T + U did not reduce the contact angle and affected negatively the mechanical properties, except to microtensile bond strength and hardness of the caries lesions infiltrated / Doutorado / Materiais Dentarios / Doutora em Materiais Dentários

A potentiometric method which is devised to be rapid and convenient for determining ionization constants for water, weak acids (or bases), and certain solids in mixed solvents is described. The method has been applied to the determination of ionization for water, acetic acid, benzoic acid, and phenol and the solubility product constant for silver chloride in mixtures of water with methanol, ethanol, acetone, tetrahydrofuran, and p-dioxane containing from 0 to 70 mass percent organic co-solvent at several temperatures between 10 and 40°C. Results are used to study the thermodynamics of ionization in each mixture which is discussed relative to various topics of ion-ion, ion-solvent, ion-molecule, molecule-solvent, and solvent-solvent interactions on the basis of theories of electrostatics, salvation, and solvent and solution structure. A calorimetric technique applied to the investigation of dimerization of benzoic acid, m-toluic acid, and o-toluic acid in benzene and toluene at 25°C as a preliminary study of the author is briefly mentioned in Appendix E.

No description available.