¿Son los parámetros electrocinéticos, constantes con la composición química?: Influencia de la especiación química en los parámetros electrocinéticos del sistema Fe(III)/Fe(II) en H2SO4
In this work, the influence of the predominant iron-sulfate species, on the kinetics of the Fe(lll)/Fe(ll)/H2S0,JH20 redox system, is shown. This was accomplished by: (a) construction of predominance zone, molar fraction and Pourbaix type diagrams, using the generalized species and generalized equil...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 1997 |
| País: | México |
| Institución: | Universidad Autónoma Metropolitana |
| Repositorio: | Repositorio Institucional de la UAM Iztapalapa |
| Idioma: | español |
| OAI Identifier: | oai:bindani.izt.uam.mx:6d56zw69h |
| Acceso en línea: | https://doi.org/10.24275/uami.6d56zw69h |
| Access Level: | acceso abierto |
| Palabra clave: | info:eu-repo/classification/LEM/Electroquímica info:eu-repo/classification/LEM/Especiación (Química) info:eu-repo/classification/LEM/Electrochemistry info:eu-repo/classification/LEM/Speciation (Chemistry) info:eu-repo/classification/cti/2 |
| Sumario: | In this work, the influence of the predominant iron-sulfate species, on the kinetics of the Fe(lll)/Fe(ll)/H2S0,JH20 redox system, is shown. This was accomplished by: (a) construction of predominance zone, molar fraction and Pourbaix type diagrams, using the generalized species and generalized equilibrium concepts. (b) the experimental determination of the following parameters: diffusion coefficient (D), heterogeneous constant (k"), charge transfer coefficients (a) and activation energies (AH*), from different predominance regions. (c) comparison of the obtained parameters with the diagrams constructed. The thermodynamic study allowed us to demonstrate that with small changes in solution pH, the chemical species present are different, changing from FeHSOi' , FeSOi, Fe(SO4)2. This study enables the selection of the appropriated experimental conditions to associate the different contributions of the chemical species present, to the kinetic parameters. When the diffusion properties of the system were evaluated, it was concluded that conversely to what is the general use, D cannot be considered equal for different species of the same system. It was found that a is independent for the different species, when pS04' is constant. It was also found that k" is diminished with changes in the chemical species in the following order: ko > ko > ko FeHS0;' FeSOi Fe(SO4)2 Although it was not possible to explain completely the similar values of AH* for the different predominant species, this effect may be the result of a conjunction between the reaction mechanism and rearrangements of the solvent molecules. |
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