Activation energies of water vaporization from the bulk and from laponite, montmorillonite, and chitosan powders

DSC has been employed to measure the vaporization kinetics of water from the bulk and from wet powders of laponite, Na-montmorillonite, and chitosan. The application of isoconversional kinetic analysis to the vaporization rate data has yielded the following average effective activation energies: 43.80 ± 0.03, 47.9 ± 0.4, 52.6 ± 0.9, and 56.2 ± 0.2 kJ mol−1 for vaporization from the bulk, laponite, sodium montmorillonite, and chitosan, respectively. A moderate increase in the activation energy is comparable to the hydrogen bond energy and can be explained by interaction between water and solid surfaces.

• DSC is used to measure the vaporization kinetics of water from the bulk and three wet powders.
• Isoconversional kinetic analysis is used to determine effective activation energies of vaporization.
• For vaporization of bulk water the activation energy is similar to the vaporization enthalpy.
• For wet powders the activation energies are larger by the energy of hydrogen bond.