Desenvolvimento de materiais poliméricos com vista à sua incorporação em membranas betuminosas

O principal objectivo deste trabalho foi o estudo da incorporação de novos materiais poliméricos em membranas betuminosas. Assim, foram sintetizados novos poliésteres polióis, com pesos moleculares semelhantes, analisados através das titulações dos grupos hidroxilo e ácido carboxílico terminais, e estruturas diferentes. Os polímeros foram sintetizados com base em ácidos diméricos, Unidyme 18 e glicóis, monopropilenoglicol e neopentilglicol no caso do polímero linear, já para o polímero tri-funcional utilizou-se trimetilolpropano e monopropilenolglicol. Estas matérias-primas servem de suporte à produção dos prepolímeros e quasi-prepolímeros reactivos de isocianato terminal para a modificação dos betumes, sendo as suas caracterizações realizadas através de espectroscopia de infravermelhos e ensaios de viscosidade. Foram preparadas as misturas com o betume de grade 160/220, provenientes da refinaria de Sines e do Porto com adição de teores de 5%, 10& e 15% de um prepolímero PRP1 e de um quasi-prepolímero. Ensaios de engenharia e qualidade, foram realizados a diversos betumes convencionais e modificados, nos laboratórios industriais das empresas Lusasfal e Probigalp como parte integrante no conhecimento dos procedimentos normativos para este tipo de ensaios, nomeadamente o ensaio de penetração, ponto de amolecimento, viscosidade dinâmica, apoiando igualmente um estudo de reprodutibilidade inter-laboratorial. Os betumes 160/220 previamente modificados com aPP e SBS, foram caracterizados reologicamente à temperatura ambiente na zona da viscoelasticidade linear

20th International Symposium on Solubility Phenomena and Related Equilibrium Processes: book of abstracts

TheWelcome to the 20th edition of the International Symposium on Solubility Phenomena and Related Equilibrium Processes held at the Polytechnic Institute of Bragança, in Portugal, from 4 to 9 of September, 2022, including the meeting of IUPAC Subcommittee on Solubility and Equilibrium Data (SSED). This biennial IUPAC symposium once again gathers international experts on solubility studies, or related subjects, to exchange scientific research and technological applications within the academic, scientific, and technical communities. From ancient Greece, the concept of a symposium encompasses the discussion in a vivid, enlightening, and convivial way. The current impediments to set up an in-person meeting did not limit this spirit or its objectives. The symposium aims to celebrate creativity, diversity, and friendship among participants, promoting the exchange of ideas and fruitful interactions. For that purpose, we have about 110 delegates from 25 countries, and your active participation is highly acknowledged. The general importance of solubility phenomena and associated physical properties is addressed in a variety of settings ranging from green chemistry to nuclear waste disposal, always envisaging applications for a sustainable development. This edition includes the contribution of 7 invited lectures and 48 oral presentations distributed in eleven sessions, and 34 posters that will be presented in two dedicated sessions. The abstracts cover a broad range of topics in search for innovative solutions in a sustainable development framework (e.g., greenhouse gases solubility, deep eutectic solvents and ionic liquids applications, remediation of mining and industrial impacts, mineral recovery from brines and seawater and energy storage, among others). Two additional workshop sessions organized within the activities of the project “Workshop on Assessment of Reliability and Uncertainty of Solubility Data” will be open to the participants on Wednesday afternoon, aiming to give fundamental and practical knowledge on good practices for phase equilibria measurements, data analysis, and reporting high quality data to the scientific community. The Franzosini award will be announced in a special session on Friday, in recognition of a promising young contributor to this area. On that same day, the best poster and oral presentation by young scientists will be also awarded. Finally, we would like to express again our deepest appreciation to all the participants, but also to the members of the Organizing Committee and International Advisory Board for their contribution to the conference and acknowledge the institutional support of IUPAC, SSED, Instituto Politécnico de Bragança, Centro de Investigação de Montanha, Sociedade Portuguesa de Química, Springer, and the reference SCI publications Journal of Solution Chemistry and Pure and Applied Chemistry.info:eu-repo/semantics/publishedVersio

An association UNIFAC model for aqueous and alcohol solutions of sugars

In this work, a modified UNIFAC model [1] that explicitly takes into account association effects is applied to mixtures containing common sugars, alcohols and water. Following the same strategy adopted before [2], four residual groups were defined to represent the sugars family: the pyranose ring (PYR), the furanose ring (FUR), the osidic bond (-O-) and the hydroxyl ring group (OH ring) [2]. For the association term, a general two sites OH associating group is used to represent association effects in these solutions, allowing a straightforward extension to multicomponent mixtures. Correlation of both solvent activity properties (water activities, vapour pressures, boiling and freezing points of aqueous D-glucose and D-fructose solutions) and sugars (D-fructose, D-glucose and sucrose) solubility in water, ethanol and methanol give very good results. Satisfactory predictions are obtained for vapour-liquid equilibrium and solid-liquid equilibrium of ternary and quaternary mixtures of sugars in mixed solvents

Partial molar volumes of amino acids in aqueous solutions of magnesium chloride

The lack of a deep molecular picture of the interactions which govern the biochemistry of vital processes is still one critical issue in this area, which limits the development of pharmaceutical solutions for diseases induced by biochemical disorders [1] and the improvement of the efficiency of biotechnological processes [2]. In this concern the study of protein-electrolyte interactions is of most importance. Hydrophobic, charged atomic groups and ions are components of almost every biologically important systems, but proteins are so complex that is useful to investigate the interaction of model compounds such as amino acids [3]. In the last decade much attention has been devoted to the partial molar volumes and hydration properties of amino acids in electrolyte solutions, which are the subject of this study

Liquid–liquid equilibria of mixtures containing methyl acetate + methanol + hexane or heptane

This paper reports the results of a new experimental study of liquid–liquid equilibria for the mixtures methyl acetate + methanol + hexane or heptane at atmospheric pressure and at (268.15, 278.15, 288.15, and 298.15)K. The equilibrium compositions were measured by gas chromatography from samples split isothermally into a glass-stirred device, and phase diagrams are reported at each temperature. The experimentally determined liquid-liquid equilibria were satisfactorily correlated by the NRTL and UNIQUAC equations. A comparative analysis was performed by application of UNIFAC group contribution method and its modifications to predict experimental liquid–liquid equilibria (LLE) behavior of these ternary mixtures. A poor prediction was observed from these contribution methods

Application of the stretched simulated annealing method in the stability analysis of multicomponent systems using excess gibbs energy models

In this work, the Stretched Simulated Annealing Method was applied to identify the stationary points of the tangent plane distance function defined for the Gibbs energy. The classic excess Gibbs energy Non Random Two Liquid model was used for these studies in several multicomponent mixtures, for which specific numerical difficulties were shown. The results obtained by applying the methodology developed in this work were very satisfactory

Partial molar volumes of glycine and L-Alanine in aqueous MgSO4 solutions between 278.15 and 308.15 K

In this work, partial molar volumes of glycine and L-alanine in aqueous solutions of magnesium sulphate at (0.0, 0.1, 0.3, 0.7 and 1.0) molal were obtained between 278.15 K and 308.15 K. Additionally, partial molar volumes of transfer at infinite dilution and hydration numbers were calculated. In general, transfer volumes are higher for glycine then L-alanine. From the transfer volumes, it can be concluded that the predominant interactions are pairwise between ions and zwitterionic centers of the amino acids. On the other hand, hydration numbers are higher for L-alanine than glycine. Dehydration of the studied amino acids is observed, rising either temperature or salt molality.This work is supported by project Project PEst-C/EQB/LA0020/2013, financed by FEDER through COMPETE - Programa Operacional Factores de Competitividade and by FCT - Fundação para a Ciência e a Tecnologia. This work was also co-financed by QREN, ON2 and FEDER (Project NORTE-07-0162-FEDER-000050)

Destilação extrativa: aplicação de agentes de separação não-voláteis

No intuito de contribuir para um melhor conhecimento dos processos de destilação extrativa recorrend o a solutos não - voláteis, n este trabalho é analisad o o efeito da adição de sais e líquidos iónicos no equilíbrio líquido - vapor de algumas misturas importantes na indú stria química, tais como etanol + água, 1 - propanol + água, 2 - propanol + água, acetona + metanol, acetato de metilo + metanol e clorofórmio + et anol. O conjunto de solutos não - voláteis contemplado é formado por Ca(NO 3 ) 2 , CuCl 2 , NaI, KI, LiNO 3 , LiCl, NaSCN, CH 3 COOK, CaCl 2 , [BMIM][Cl] e [EMIM][triflate] . Recorre - se a dois métodos de carácter preditivo, os modelos de Wilson e NRTL modificados, para calcular os diagramas de equilíbrio líquido - vapor. No caso da adição de um sal a misturas binárias de solventes verifica - se que, em geral, ambos os modelos conseguem prever de forma qualitativa o deslocamento do azeótropo. Para o modelo de Wilson modifica do os erros absolutos médios forem para a composição na fase de vapor ∆ y = 0.049 e para a temperatura ∆ T = 1.17 o C . Para o modelo NRTL modificado os correspondentes valores são ; ∆ y = 0.048 e ∆ T = 0.88 o C . Para as misturas contendo dois solventes e um liquido iónico, ambos os modelos descrev em de forma pouco satisfatória o equilíbrio líquido - vapor dos dois sistemas ternários estudados (etanol + água + [BMIM][Cl]; 1 - propanol + água + [EMIM][triflate]). Será necessário estudar a aplicação desta metodologia a um conjunto mais amplo de sistemas. De toda a forma e stes modelos constituem uma ferramenta útil na previsão do efeito de sais n o equilíbrio líquido - vapo

Phase equilibria in sugar solutions using the A-UNIFAC model

http://apps.isiknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=2&SID=V21Di6PajaHLPoM3@AJ&page=1&doc=1&colname=WOSIn this work, a modified UNIFAC model that explicitly takes into account association effects is used to describe the thermodynamic properties of phase equilibria of mixtures containing common sugars, alcohols, and water. Three main groups were defined to represent the sugars family: the sugar ring (pyranose and furanose), the osidic bond (-O-), and the hydroxyl ring group (OHring). For the association term, a general two-site OH associating group is used to represent association effects in these solutions, allowing a straightforward extension to multicomponent mixtures. Correlation of both solvent properties (osmotic coefficients, water activities, vapor pressures, and boiling and freezing points of binary aqueous sugar solutions) and sugar solubility in water and alcohols gives very accurate results. Good predictions are obtained for vapor-liquid equilibrium and solid-liquid equilibrium of ternary and quaternary mixtures of sugars in mixed solvents.O.F. acknowledges financial support from the PRAXIS program, FCT, Lisbon, Portugal

Extension of the A-UNIFAC model to mixtures of cross- and self-associating compounds

http://apps.isiknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=4&SID=V21Di6PajaHLPoM3@AJ&page=1&doc=1&colname=WOSIn the present work an extended UNIFAC group contribution model is used to calculate activity coefficients in solutions containing alcohols, water, carboxylic acids, esters, alkanes and aromatic hydrocarbons. The limiting expressions for the association contribution to the activity coefficients at infinite dilution are presented and discussed. A new set of interaction parameters between associating and non-associating functional groups is reported. This set of parameters is applied in the association model to predict vapor–liquid, liquid–liquid equilibrium and infinite dilution activity coefficients.The authors are grateful to the National Research Council of Argentina (CONICET) and to Universidad Nacional del Sur (UNS) for financial support. O. Ferreira acknowledges financial support from the PRAXIS program, FCT, Lisbon, Portugal (SFRH/BD/879/2000)