Ag-Functionalized Clinoptilolite for Air Purification: Comparative Study of Decontamination and Antibacterial Efficacy of Metallic vs. Ionic Silver

Abstract

Indoor air purification is essential for maintaining human health, as airborne pathogens and pollutants significantly impact respiratory health. Airborne droplets containing pathogens can be dispersed by air currents, contributing to the spread of infectious diseases. Additionally, particulate matter and volatile organic compounds (VOCs) in the air are linked to respiratory infections and cancers. Effective air purification solutions are necessary to mitigate these risks. Natural materials like zeolites, especially clinoptilolite, have gained attention due to their textural properties and high adsorption capacities. Clinoptilolite, a widely available and cost-effective zeolite, is known for its ion-exchange capabilities and its ease of functionalization for improved air decontamination and antibacterial applications.This study explores the functionalization of natural clinoptilolite with silver using two green methods to enhance its decontamination potential. The first method involves the in situ reduction of silver nanoparticles with tannic acid (Clino-AgNPs), while the second introduces silver in its ionic form (Clino-Ag) using the same silver precursor. The study compares these methods to investigate the roles of tannic acid and metallic silver in air purification.Clino-Ag and Clino-AgNPs samples were characterized using FESEM, XRD, EDS, and STEM to analyze their morphology. Textural properties were examined through N2 and CO2 adsorption, while catalytic activity was assessed via CO and ethylene oxidation. Antibacterial activity was tested by exposing samples to bacterial bioaerosols and monitoring bacterial growth. Functionalization with metallic silver proved most effective, while both samples exhibited strong antibacterial properties, showing potential for enhanced indoor air purification.

Keywords: air purification, natural zeolite clinoptilolite, silver, environmental catalysis, antibacterial, VOC oxidation