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

Abstract

In this study, the effect of activation with HCl on the ammonia adsorption properties of natural Gördes clinoptilolite was investigated 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 of different concentrations (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 M) at 90°C for 4 h. The adsorbents were characterized using XRD, XRF, FT-IR, TGA, DTA and N2 adsorption techniques. 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 and partial destruction of the structure, but also affected the thermal behaviour and gas retention of the clinoptilolite. Nitrogen adsorption results showed that it is possible to improve the specific surface area and micropore properties 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) in this study were compared with the ammonia removal data of natural and synthetic zeolites (1.77 - 9.32 mmol.g-1) reported in previous studies.