On the effect of thermal activation on the surface chemistry of natural mineral sorbents

\nThe article discusses adsorbents, their characteristic features, structural sizes, geometric forms, porosity, the concept of porosity and the influence of their thermal activation on the structure and sorption parameters of natural mineral sorbents - Angren kaolin and Azkamar bentonite. Here is given the chemical composition of kaolin and bentonite clay samples before and after thermal activation. Thermal activation of kaolin clay at 1023K is shown, which has almost no effect on the content of basic oxides in the clay mineral. It leads to the removal of adsorbed moisture and partially constitutional water, as a result of which the mass loss on ignition (WLP) of a thermally activated kaolin clay sample is reduced. The adsorption isotherms of water vapor on thermally activated samples of kaolin and bentonite have an S-shape according to the BET classification, which is due to capillary condensation in the P/P-1.0 region. All isotherms are characterized by the presence of a hysteresis loop over the entire range of relative pressures. The reason for the appearance of a hysteresis loop in the case of sorption of water vapor is associated with the swelling of clays in the vapor phase. The change in the chemical composition of the initial and clays activated at 1023K is shown in the form of a table. Based on the research, it was concluded that during thermal activation of PMS, processes associated with dehydration and dehydroxylation occur, which leads to changes in porosity, specific gravity, and total pore volume.\n