Surface properties evolution of attapulgite by IGC analysis as a function of thermal treatment

At low temperatures, thermal treatment of attapulgite clay causes a loss of mass due to the elimination of linked, zeolitic and crystallized water molecules. At high temperatures, there is a junction of particles until total melting of the attapulgite fibers. This transformation reduces significantly the volume of the porous network resulting in the drop in the value of specific surface area and causing important changes in the textural, structural and surface properties of the raw attapulgite. The inverse gas chromatography shows sensitivity of the attapulgite sample to the effect of temperature through the decrease of the dispersive component of the surface energy γ s d . The evolution of the nanomorphological index, a measurement of the surface nanorugosity, follows the appearance of surface roughness on carbonates with the increase of the temperature. The surface heterogeneity, determined by calculating the distribution functions of adsorption energies also underlines the morphology changes and the formation of new phases under the effect of temperature.