WATER VAPOR ADSORPTION PERFORMANCE OF KA ZEOLITE SYNTHESIZED FROM LOCAL KAOLIN RAW MATERIAL

Abstract

The water vapor adsorption properties of KA (3A) zeolite, synthesized from Angren kaolin via metakaolin formation, hydrothermal crystallization, and ion exchange, were studied calorimetrically. The isotherm corresponded to IUPAC Type I, confirming the material's microporous nature, with adsorption proceeding through three stages: ion-dipole binding of water molecules to K⁺ sites, hydrogen-bond-driven clustering within the α-cavities, and near-linear filling of the remaining micropore volume. The maximum adsorption capacity reached 10.34 mmol/g, with approximately 1 mmol/g of primary active sites. Gibbs free energy analysis confirmed a stepwise mechanism, in which water molecules form sequential ion-molecular complexes from 1H₂O:KA to 10H₂O:KA.