Kinetic and Thermochemical Analysis of Rubidium Jarosite Decomposition in Alkaline Media

Rubidium jarosite was synthesized as a single phase by precipitation from aqueous solution. X ray diffraction and SEM-EDS analysis showed that the synthetic product is a solid rubidium jarosite phase formed in spherical particles with an average particle size of about 35 m. The chemical analysis sho...

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Bibliographic Details
Published in:AIP conference proceedings 2012-03
Main Authors: Perez-Labra, Miguel, Romero-Serrano, Antonio, Salinas-Rodriguez, Eleazar, Avila-Davila, Erika, Juarez-Lopez, Guillermo, Hernandez-Avila, Juan
Format: Article
Language:English
Subjects:
Aqueous solutions
Calcium
Decomposition
Iron
Jarosite
Mathematical models
Rubidium
X-ray diffraction
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Summary:Rubidium jarosite was synthesized as a single phase by precipitation from aqueous solution. X ray diffraction and SEM-EDS analysis showed that the synthetic product is a solid rubidium jarosite phase formed in spherical particles with an average particle size of about 35 m. The chemical analysis showed an approximate formula Rb0.9432Fe3(SO4)2.1245(OH)6. The decomposition of jarosite in terms of solution pH was thermodynamically modeled using FACTSage by constructing the potential-pH diagram at 298.15 K. The E-pH diagram showed that the decomposition of jarosite leads to a goethite compound (FeOoOH) together with Rb+ and SO42-ions. The experimental Rb-jarosite decomposition was carried out in alkaline solutions with five different Ca(OH)2 concentrations. The decomposition process showed a so called "induction period" followed by a progressive conversion period where Rb+ and SO42-ions formed in the aqueous solutions, whereas calcium was incorporated in the solid residue and iron gave place to goethite. The kinetic analysis showed that this process can be represented by the shrinking core chemically controlled model with a reaction order with respect to Ca(OH)2 equal to 0.4342 and a calculated activation energy of 98.70 kJ mol-1.
ISSN:0094-243X