Synthesis And Characterization Of Zeolites NaX And NaA From Kaolin

In this study, NaA and NaX zeolites were synthesized using locally available Angren kaolin as a low-cost raw material. Pretreatment of the kaolin with oxalic acid reduced the content of iron and titanium oxides, resulting in an increased Si/Al ratio and creating favorable conditions for zeolite formation. NaA zeolite was synthesized under hydrothermal conditions in a NaOH medium, whereas NaX zeolite was synthesized in the presence of additional sodium silicate. The obtained products were comprehensively characterized using XRD, SEM–EDS, and FTIR techniques. The XRD diffractograms confirmed the formation of a cubic LTA-type crystalline structure for NaA zeolite and a FAU-type faujasite structure for NaX zeolite. FTIR analysis identified characteristic vibrations associated with hydroxyl groups, water molecules, and the zeolite framework, confirming the structural features of the synthesized phases. SEM–EDS results revealed an ordered cubic crystal morphology for NaA zeolite and an aggregated crystal morphology for NaX zeolite. BET analysis showed specific surface areas of 640.8 m 2 /g for NaX zeolite and 458.5 m 2 /g for NaA zeolite. The corresponding water vapor adsorption capacities were 7.82 mmol/g and 6.75 mmol/g, respectively. Nitrogen adsorption results indicated that NaX zeolite possesses a more developed pore system, whereas NaA zeolite exhibits a predominantly microporous structure. The obtained structural and adsorption characteristics are generally consistent with those reported in the international literature for NaX and NaA zeolites synthesized from low-cost raw materials. The identified pore structure, specific surface area, ion-exchange properties, and water adsorption characteristics indicate the potential applicability of these materials in areas such as water purification, ion exchange, adsorption of various pollutants, and adsorption-based gas separation. These results demonstrate the feasibility of obtaining functional zeolite materials from Angren kaolin and may provide a basis for further applied investigations.