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.