Modification of melt-blown polypropylene filters with spent green tea-mediated green synthesis of nanosilver for antibacterial activities and air purification.

Air pollution containing microorganisms presents a significant risk to human health. It is crucial to create air filters that are highly efficient for air purification and conducive to human health. Hence, this work aims to develop a filter based on melt-blown polypropylene (PP) spray-coated with green-synthesized silver nanoparticles (AgNPs). A bio-reducing agent from extracted spent green tea (SGT) was used in the AgNPs synthesis. Polyvinyl alcohol cross-linked with citric acid was used as a binder in spray coating. Effects of silver nitrate (AgNO3) concentrations, viz. 50, 100, and 150 mM, were investigated on AgNP formation and properties of spray-coated PP filter. Based on the results, the spray-coated PP filter with synthesized AgNP at 100 mM AgNO3 (AgNPs-100) showed the highest inhibition zones of both Gram-positive and Gram-negative bacteria. The tensile strength of the spray-coated PP filter with AgNPs ranged from 1309–1478 kPa, which was higher than that of the neat PP filter. The particle filtration efficiency of the spray-coated PP filter with AgNPs-100 for various particle sizes was enhanced by 27.95–447.04% compared to the neat PP filter. Moreover, the particle filtration efficiency of the spray-coated filter with AgNPs-100 was higher than 97% for particles of 0.3 μm, including PM1.0 and PM2.5. Therefore, the proposed spray-coated PP filter had a high potential to be a promising disinfecting filter for biomedical and hygienic applications. [ABSTRACT FROM AUTHOR]