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Updated: Feb 14, 2026

Light-driven Enzymatic Decarboxylation
Published on: May 22, 2016
Thermally decarboxylated sodium bicarbonate: Interactions with water vapour, calorimetric study
Natalia Volkova1,2, Henri Hansson3, Lennart Ljunggren1
1Department of Biomedical Science, Malmö University, SE-205 06, Malmö, Sweden.
Abstract:
Isothermal titration calorimetry (ITC) was used to study interactions between water vapour and the surface of thermally converted sodium bicarbonate (NaHCO3). The decarboxylation degree of the samples was varied from 3% to 35% and the humidity range was 54-100%. The obtained enthalpy values were all exothermic and showed a positive linear correlation with decarboxylation degrees for each humidity studied. The critical humidity, 75% (RHo), was determined as the inflection point on a plot of the mean-ΔH kJ/mole Na2CO3 against RH. Humidities above the critical humidity lead to complete surface dissolution. The water uptake (m) was determined after each calorimetric experiment, complementing the enthalpy data. A mechanism of water vapour interaction with decarboxylated samples, including the formation of trona and Wegscheider's salt on the bicarbonate surface is proposed for humidities below RHo.
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