Water at Curved Carbon Surface: Mechanisms of Adsorption Revealed by First Calorimetric Study

Water adsorption isotherms and calorimetrically measured enthalpy of this process are reported for a series of modified chemically single and multiwalled nanotubes. On the basis of calorimetric measurements, entropy of adsorption is calculated and discussed. Next the data are described using popular models of adsorption, and finally a new approach for simultaneous description of water adsorption and enthalpy of this process is discussed. On the basis of the results of this model, four different possible mechanisms of water adsorption in nanotubes are proposed.