Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
675999 | Thermochimica Acta | 2007 | 5 Pages |
Abstract
A calorimetric study of kinetics and thermodynamics of the attack of a synthetic fluorapatite by a mixture of sulfuric and phosphoric acids is undertaken at 55 °C. The global enthalpy of the attack equals â409.3 kJ/mol. The recorded thermograms show two peaks leading to calcium sulfate hemihydrate and dihydrate, respectively. The deconvoluted curves were analysed iteratively. A kinetic mechanism based on simultaneous reactions has been proposed for the first peak and confirmed thermochemically by comparing the enthalpies deduced from iteration and that determined from experimental and calculated routes. The second peak of the thermogram was attributed to transformation of calcium sulfate hemihydrate into gypsum according to a dissolution/precipitation scheme. These phenomena are of order one and two, respectively.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Fluid Flow and Transfer Processes
Authors
K. Antar, M. Jemal,