Tannic acid-assisted green functionalization of Clinoptilolite: A step-by-step characterization of silver nanoparticles in situ reduction

Recently, the reduction of airborne pathogens and the need for clean and controlled air have gained researchers’ attention. The use of natural zeolites and in particular clinoptilolite as solutions for wastewater treatment and air purification has proven effective due to the remarkable ability of these materials to adsorb toxic compounds. In this work, the clinoptilolite powders are subjected to an eco-friendly in situ functionalization process using tannic acid to induce silver nanoparticles (AgNPs) nucleation, improving the antimicrobial potential of the zeolite. The focus of this work is the characterization of this multi-step functionalization process by morphological, compositional and structural analyses. The Fourier transform infrared investigation confirms the successful functionalization of clinoptilolite with tannic acid, establishing a foundational step in the process. Successive morphological and compositional analyses verify the introduction of AgNPs onto the zeolite surface, revealing a highly uniform distribution of AgNPs. Furthermore, structural analysis verifies the presence of metallic silver. Finally, the antibacterial efficacy was verified for both Gram-positive and negative bacteria by zone of inhibition test. The functionalization of clinoptilolite with AgNPs, achieved without heat treatment or harmful chemicals, offers a promising solution for absorbing toxic compounds while simultaneously preventing bacterial growth. In the future, this innovative approach could play a crucial role in air purification systems targeting airborne pathogens. Clinoptilolite successfully functionalized with AgNPs via TA green in situ reduction (Clino-TA-AgNPs) demonstrates antibacterial activity against both Gram-positive S. epidermidis and Gram-negative E. coli.