Boosting silver loading and functionality in Clinoptilolite via tannic acid reduction: a comparative study of ionic and metallic silver for air purification

Air purification is essential for protecting human health, as airborne pathogens and pollutants contribute to respiratory infections. Natural materials such as zeolites, particularly clinoptilolite, have attracted attention due to their high adsorption capacity and ion exchange properties, making them promising for air purification. This study investigates the functionalization of natural clinoptilolite with silver to enhance its catalytic and antibacterial performance using two green methods. The first involves ion exchange to introduce silver ions (ClinoAg), while the second uses tannic acid to promote the formation of silver nanoparticles (Clino-AgNPs), keeping the precursor amount constant. The materials were characterized by FESEM, XRD, EDS, and STEM, while textural properties were analyzed via N₂ and CO₂ adsorption. Catalytic activity was tested for CO and ethylene oxidation, and antibacterial efficacy was evaluated using bacterial bioaerosols. Results showed that morphology influenced performance, with metallic silver providing superior catalytic activity, while both forms exhibited strong antibacterial properties