Structural and ammonia adsorption properties of the Gördes clinoptilolite after HCl acid treatment

The effect of activation with HCl on the ammonia adsorption characteristics of natural Gördes clinoptilolite was studied in order to evaluate the usability of this mineral in various environments where ammonia removal is required, such as livestock facilities. Clinoptilolite was treated with HCl solutions (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 M) at 90°C for 4 h. XRD, XRF, FT-IR, TGA, DTA and N2 adsorption techniques were used for structural and thermal characterization of the adsorbents. NH3 adsorption isotherms were measured volumetric analysis at 298 K up to 100 kPa. Acid activation not only caused textural and structural changes such as removal of exchangeable cations but also affected the thermal behavior and gas retention of the clinoptilolite. Nitrogen adsorption results showed that it is possible to improve the specific surface area and micropore area values of clinoptilolite with acid activation up to 1.5 M. In addition, the NH3 adsorption capacities of clinoptilolite samples (4.33-5.01 mmol.g-1) were compared with the ammonia removal data of natural and synthetic zeolites (1.77 - 9.32 mmol.g-1) reported in previous studies.