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The COVID-19 pandemic has led to a greater need for non-transmissible products like face masks, which are effective in preventing the spread of the virus but come with challenges such as reduced breathability and biohazard waste. This study addressed these issues by integrating green-synthesized zinc oxide particles and Azadirachta indica extract into nonwoven face masks. Eight samples were developed using the needle punching nonwoven method and then calendared. These samples were coated with varying levels of A. indica extract (0, 15, and 30 wt.%) and ZnO particles (0, 2, and 4 wt.%) using the dip and dry method. Comparative analyses were performed with market-available masks (MA) and untreated masks (US) for air permeability, thermal resistance, tensile behavior, and antimicrobial efficacy against Staphylococcus aureus. The untreated masks had the highest air permeability at 826 mm/s, which decreased with higher A. indica and ZnO concentrations. Scanning electron microscope (SEM) images confirmed even distribution of ZnO particles. Thermal resistance and tensile properties were directly linked to A. indica and ZnO concentrations. The sample treated with 30 wt.% A. indica and 4% ZnO showed the highest thermal resistance (0.042 m2K/W), elongation (92% CD, 84% MD), and tenacity (0.93 g/tex CD, 0.87 g/tex MD). Increased A. indica and ZnO concentrations demonstrated significant antimicrobial activity, with a maximum zone of inhibition of 8.03 mm recorded at 30 wt.% A. indica and 4 wt.% ZnO particles. These findings suggest potential applications for developing surgical facemasks with improved efficacy. [ABSTRACT FROM AUTHOR]

We report the photosensitization of electrospun titania nanofibers, with a mean diameter of 195 nm, by low bandgap silver sulfide nanoparticles of 11-23 nm mean size with the aim of treating heavy metal ions and pathogenic bacteria simultaneously under simulated solar light irradiation. The 17 nm Ag 2 S/TiO 2 nanofibers showed 90% photocatalytic reduction of Cr(vi) at pH of 3 with a pseudo-first order rate constant of 0.016 min -1 which is significantly better than the previously reported for Ag-Ag 2 S/TiO 2 composite particles. The antibacterial capability of the Ag 2 S/TiO 2 nanofibers was evaluated via photo-disinfection of the Gram-positive and Gram-negative bacterial strains. The smallest sized 11 nm Ag 2 S/TiO 2 nanofiber showed the best bactericidal efficiency of 100% and 90.6% against Gram-negative E. coli and Gram-positive S. aureus after 1 h of irradiation, respectively, whereas, only 50% E. coli and 41% S. aureus were found to be inactivated in dark. Furthermore, a UV-O 3 treatment of the 11 nm Ag 2 S/TiO 2 nanofibers remarkably enhanced the antibacterial activity where 89% E. coli and 81% S. aureus were inactivated in just 10 min of the irradiation. Enhanced photocatalytic activity is attributed to the efficient charge separation and transfer and reduced electron-hole recombination induced by the effective heterojunction formation between TiO 2 and the optimally sized Ag 2 S nanoparticles. The disinfection nature of the Ag 2 S nanoparticles, role of the generated hydroxyl species under irradiation, and the cell wall damage mechanism is also discussed. This study demonstrates the potential use of these multifunctional composite TiO 2 nanofibers for water remediation., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

TiO 2 nanofibers, with mean diameter ~200 nm, were fabricated by electrospinning and successfully photosensitized with low bandgap Ag 2 S nanoparticles of 11, 17, 23 and 40 nm mean sizes, with corresponding loading of 4, 10, 18 and 29 wt.% Ag 2 S, respectively. 17 nm Ag 2 S@TiO 2 nanofibers exhibited optimal activity in the photodegradation of methylene blue under simulated sunlight with pseudo-first order rate constant of 0.019 min -1 compared to 0.009 min -1 for pure TiO 2 nanofibers. In spite of greater visible-light absorption and reduced bandgap, larger than 17 nm Ag 2 S nanoparticles exhibited sluggish photodegradation kinetics probably due to less photo-induced carriers generation in TiO 2 and reduced electron injection rates from the larger sized Ag 2 S into TiO 2 . Furthermore, a UV-O 3 surface treatment induced excess Ti 3+ surface states and oxygen vacancies which synergistically enhanced the photodegradation rate constant to 0.030 min -1 for 17 nm Ag 2 S@TiO 2 sample which is ~70% better than the previously reported for Ag 2 S/TiO 2 hierarchical spheres. This was attributed to the efficient charge separation and transfer driven by increased visible-light absorption, bandgap narrowing and reduced electron-hole recombination rates. The present study demonstrate the potential utilization of Ag 2 S@TiO 2 nanofibers in filtration membranes for removal of organic pollutants from wastewater.