The investigations of adsorption layers on material surfaces by means of the thermogravimetry technique

A simple method has been adopted to obtain information about properties of the adsorbed liquid films, adsorbate-adsorbent interactions and the heterogeneity surfaces of the materials studied. The method utilizes Q-TG mass loss and the first derivative Q-DTG mass loss curves with respect to temperature and time obtained during programmed liquid thermodesorption in quasi-isothermal conditions. The obtained Q-TG and Q-DTG mass loss curves consist of steps and inflections which are associated with the properties of adsorbed liquid films and mechanism of the solid surfaces wetting process. Moreover, the Q-DTG curves reflect the energetical and geometrical heterogeneity of the solid surfaces. The heights of these steps and inflections depend on the adsorption capacity, desorption energy, the nature and number of the active centers of the samples studied. The values of the total porosity and the adsorption capacity obtained by this method are in good agreement with those estimated on the basis of independent methods. The experimental results provided novel data on the properties of liquid adsorbed films, heterogeneous properties of solid surfaces and thermal stability of the liquid/solid interface. (C) 2001 Elsevier Science B.V. All rights reserved.