Silver-Exchanged Clinoptilolite-Rich Natural Zeolite for Radon Removal from Air.

Radon (Rn) is a hazardous radioactive gas that poses significant health risks in enclosed indoor environments. This study investigates the potential of silver-exchanged clinoptilolite-rich natural zeolite (NZ-Ag) for the removal of Rn from air. Natural zeolite (NZ) was thermally treated and further modified to enhance its adsorption characteristics. The thermally treated NZ (200 °C) was first exchanged in Na form, since Na is more easily exchanged in clinoptilolite with hydrated Ag ions than the other exchangeable cations. The modification with Ag was carried out at room temperature using ultrasonic processing to obtain (NZ-Ag). The materials were characterized in terms of chemical composition, cation exchange capacity, mineralogy, total surface area, pore volume, and thermal behavior. Rn adsorption experiments were performed using a closed-circuit system, and the efficiency of NZ-Ag was compared with that of NZ. The results indicate that NZ-Ag exhibits superior Rn adsorption capacity, achieving up to 50% higher retention efficiency compared to NZ. The improved performance is attributed to enhanced adsorption facilitated by silver ion clusters interacting with radon atoms. These results suggest that silver-exchanged zeolite represents a promising material for radon mitigation in air filtration systems, with potential applications in residential and occupational settings.