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- Title
Thermodynamic properties of Fe-rich smectite-nontronite.
- Authors
Ogorodova, L.; Kiseleva, I.; Melchakova, L.; Vigasina, M.; Krupskaya, V.; Bugel'skii, Yu.
- Abstract
The results of thermochemical studies are reported for nontronite samples from the Pinares-de-Majari (Eastern Cuba) (Sample I) and Kempirsai serpentine massif (South Urals, Kazakhstan) (Sample II). The enthalpies of formation of dehydrated hydroxyl-bearing nontronites from elements were determined by melt dissolution calorimetry using high-temperature heat-flux Tiana-Calvet microcalorimeter: Δ H (298.15 K): −4958 ± 13 kJ/mol for Mg(FeMgNi)[SiAlO](OH) (I) and −5003.6 ± 8.0 kJ/mol for MgNaCa(FeMgNi)[SiAlO](OH) (II). It was determined experimentally that the enthalpy of dehydration (removal of molecular adsorption and interlayer water) of the studied nontronites is 6 ± 2 kJ per 1 mole HO. The enthalpy of formation of nontronite of theoretical composition MgFe[SiAl]O(OH) was estimated at −4750 kJ/mol. The Gibbs free energies of formation of the nontronites were calculated.
- Subjects
NONTRONITE; HEAT of formation; MICROCALORIMETRY; CALORIMETRY; SMECTITE
- Publication
Geochemistry International, 2014, Vol 52, Issue 5, p421
- ISSN
0016-7029
- Publication type
Article
- DOI
10.1134/S0016702914030057