A Comprehensive Experimental Study on the Way the Operating Conditions of the Acid Treatment of Zeolite Affect Its Chemical, Textural, and Crystallographic Properties

This study used a factorial design to examine how temperature and acid treatment duration affect the properties of Na-X zeolite. Statistical analysis showed that the difference of temperature influenced the silicon-to-aluminum ratio significantly, as measured by X-ray fluorescence. On the other hand, longer treatment, significantly affected the textural and crystallographic properties as evidenced by surface area analysis and X-Ray Diffraction (XRD). Kinetic analysis revealed selective aluminum dissolution and sodium replacement with hydrogen, resulting in irreversible structural modifications. Changes in the silica-to-alumina ratio and sodium content were analyzed using a first-order Langmuir kinetic model at different temperatures, whereas enthalpy, entropy, activation energy, and frequency factor of adsorption were determined using the Van't Hoff and Arrhenius equations, with the first two having activation energies of 43,661.8 and 35,774.3 J/mol, respectively. The surface area and pore volume increased to 446.56 m³/g and 446.56 cm³/g, respectively, after 3 h at 75°C. XRD revealed minor distortions at the highest temperature and during extended treatment, resulting in slight alterations to particle size and crystallinity, highlighting the importance of optimizing acid treatment parameters to enhance zeolite properties while preserving structural integrity.