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Calorimetry of heterogeneous systems: H+ binding to TiO2 in NaCl

S.R. Mehr·D.J. Eatough·L.D. Hansen·E.A. Lewis·J.A. Davis
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Abstract

A simultaneous calorimetric and potentiometric technique has been developed for measuring the thermodynamics of proton binding to mineral oxides in the presence of a supporting electrolyte. Modifications made to a commercial titration calorimeter to add a combination pH electrode and maintain an inert atmosphere in the calorimeter reaction vessel are described. A procedure to calibrate potentiometric measurements in heterogeneous systems to correct for the suspension effect on pH is given. The enthalpy change for proton dissociation from TiO 2 in aqueous suspension as a function of pH is reported for 0.01, 0.1, and 0.5 M NaCl. The enthalpy change for proton dissociation is endothermic, ranging from 10.5 ± 3.8 to 45.0 ± 3.8 kJ mol −1 over the pH range from 4 to 10.

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S.R. Mehr, D.J. Eatough, L.D. Hansen, E.A. Lewis, J.A. Davis. 1989. Calorimetry of heterogeneous systems: H+ binding to TiO2 in NaCl. https://doi.org/10.1016/0040-6031(89)87125-4

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Heat capacities and entropies from 8 to 1000 K of langbeinite (K 2 Mg 2 (SO 4 ) 3 ), anhydrite (CaSO 4 ) and of gypsum (CaSO 4 ·2H 2 O)

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