Microcalorimetric study of the transformation of CaSO4·2H2O in the 40 and 50wt% P2O5 solutions at 80°C

► CaSO4·2H2O (gypsum) was dissolved in 40 and 50wt% P2O5 solutions at 80°C. ► Dissolution processes were realized in a C80 SETARAM calorimeter. ► The gypsum dissolution in 40wt% P2O5 solution takes place in one step. ► Gypsum transforms into hemihydrate through a dissolution/precipitation process. A...

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Bibliographic Details
Published inThermochimica acta Vol. 545; pp. 174 - 179
Main Authors Fertani-Gmati, Meriem, Jemal, Mohamed
Format Journal Article
LanguageEnglish
Published Elsevier B.V 10.10.2012
Subjects
calcium sulfate
Calcium sulfate dihydrate
Calcium sulfate hemihydrate
calorimetry
Dissolution
Enthalpy
gypsum
Kinetic
phosphoric acid
phosphorus pentoxide
Calcium sulfate hemihydrate
Kinetic
Dissolution
Enthalpy
Calcium sulfate dihydrate
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Summary:► CaSO4·2H2O (gypsum) was dissolved in 40 and 50wt% P2O5 solutions at 80°C. ► Dissolution processes were realized in a C80 SETARAM calorimeter. ► The gypsum dissolution in 40wt% P2O5 solution takes place in one step. ► Gypsum transforms into hemihydrate through a dissolution/precipitation process. A calorimetric study of the transformation of CaSO4·2H2O (gypsum) in 40 and 50wt% of P2O5 phosphoric acid solutions is undertaken at 80°C by dissolving increasing amounts of gypsum in the same volume of liquid. The results show a simple dissolution or its transformation into hemihydrate, CaSO4·1/2H2O, depending on the acid concentration. Kinetic schemes have been developed for these processes. The kinetic and thermochemical parameters were derived iteratively and the enthalpies were compared to experimental values.
Bibliography:http://dx.doi.org/10.1016/j.tca.2012.07.013
ISSN:0040-6031
1872-762X
DOI:10.1016/j.tca.2012.07.013