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Journal of Thermal Analysis and Calorimetry
Authors: Anne G. D. Santos, Vinícius P. S. Caldeira, Mirna F. Farias, Antonio S. Araújo, Luiz D. Souza, and Allan K. Barros

has been widely used in recent years, in kinetic studies of thermal decomposition of the most varied substances. Although, this technique is subjected to various criticisms and has been questioned by several authors, a large number of articles on the

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Reaction Kinetics, Mechanisms and Catalysis
Authors: F. J. Lona-Ramírez, R. Herrera-Muñoz, V. Rico-Ramírez, F. Louvier Hernández, G. Luna-Bárcenas, and G. González-Alatorre

reactivity and the biological activity of the nitroso-compound formed [ 16 ]. In the particular case of 1,1,3-nitrosotrimethylurea, whose biological activity has been reported [ 17 ], no kinetic studies on their formation have been found. This

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Abstract  

The liquid phase reaction between maleic anhydride and 1-methyl-furan leads to an exothermic cycloaddition. The reaction enthalpy, the rate constant and the equilibrium constant are evaluated with good precision by a method of analysis using thermal data and a dynamic model based on physical properties. The mathematical models that are presented here in a simple way (first-order system) represent the reaction accurately and are useful for studying other reactions and even industrial processes.

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Thermal and kinetic study of statins

Simvastatin and lovastatin

Journal of Thermal Analysis and Calorimetry
Authors: M. Souza, Marta Conceição, M. Silva, L. Soledade, and A. Souza

Abstract  

Statins are a group of lipoproteins that are used in medicine to treat the high cholesterol level. The effectiveness of statins in reducing the cholesterol level is significant and in long time scale the reduction of the cholesterol level helps to avoid the incidence of degenerative diseases. Simvastatin and lovastatin are belonging to the ‘statins’ family, one of the pharmacologic groups used in the control of dislipidemy. The objective of this work is the thermal stability and kinetic study of the active forms of simvastatin and lovastatin. Thermal data indicated that lovastatin and simvastatin are stable up to 190 and 170°C in air and up to 205 and 203°C in nitrogen, respectively. For melting temperatures DSC curves showed good correlation with the literature data. Comparing the activation energies of the statins at heating rate of 10°C min–1, lovastatin is more stable than simvastatin under the applied experimental conditions.

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], somehow rhetorically ask: “What is truly the aim of kinetic studies and modelling?” They also answer, “It is evident that the aim is designing reactors which can successfully accomplish and improve the decomposition of a certain material for obtaining

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Journal of Thermal Analysis and Calorimetry
Authors: A. Garrido Pedrosa, P. Pimentel, D. Araújo Melo, H. Scatena, F. Borges, A. Souza, and L. Zinner

Abstract  

Ln(TFA)3⋅3AZA (Ln=La, Sm, Er; TFA=trifluoroacetate and AZA=2-azacyclononanone)compounds were synthesized and characterized by microanalytical procedures, IR spectroscopy, X-ray powder diffraction, and thermal analysis. A kinetic study using La, Sm and Er thermogravimetric curves was carried out aiming to proposing a mechanism for the thermal decomposition of such complexes.

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Abstract  

The paper deals with a kinetic study of crystal growth in gelatin and agar gels, using a technique based on radioactive tracers.204TlCl,204TlBr,204TlI,60CoC2O4 and60CoH4C4O6 crystals in gels have been obtained. The global kinetic process of appearance of crystals has been found to be made up of two distinct stages: diffusion of the ions in the gel and crystallization, having different rate constants.

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Journal of Thermal Analysis and Calorimetry
Authors: F. Fraga, V. Soto, J. Blanco-Méndez, A. Luzardo-Alvarez, E. Rodríguez-Núñez, J. Martínez-Ageitos, and M. Pérez

Abstract  

Knowledge of the the kinetic study of chitosan/genipin allow to know the different effects that time and temperature have on the cure reaction of the material. The total enthalpy of reaction, the glass transition temperature and the partial enthalpies have been determined using DSC in dynamic mode. Two models, one based on chemical kinetics and the other accounting for diffusion were used. The incorporation of the diffusion factor in the second model allowed for the cure kinetics to be predicted the whole range of conversion.

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Abstract  

The kinetics of adsorption of chromate ions has been investigated radiometrically over a wide range of concentration of chromate ions (10–6–10–2M) and temperature (303–323 K). The kinetics of the process follows essentially a first order rate law with respect to adsorptive concentration and obeys the Freundlich adsorption isotherm in the concentration range studied. In addition, the kinetics of desorption of the preadsorbed species also follows a first order rate law and the activation energy for desorption is greater than that of the adsorption process. On the basis of an adsorption kinetic study, the thermodynamic parameters have been calculated. Infrared spectroscopy has shown the chemical interaction of chromate ions on the surface of MnO2.

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Journal of Thermal Analysis and Calorimetry
Authors: Edjane F. B. Silva, Marcílio P. Ribeiro, Ana C. F. Coriolano, Ana C. R. Melo, Anne G. D. Santos, Valter J. Fernandes Jr., and Antonio S. Araujo

, Fernandes VJ , Araujo AS . Kinetic study of template removal of MCM-41 nanostructured material . J Therm Anal Calorim . 2004 ; 75 : 693 – 8 . 11. Vyazovkin , S , Lesnikovick , AI

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