ABSTRACT
An automatic lab-scaled spray-coating machine was used to deposit Ag nanoparticles (AgNPs) on textile to create antibacterial fabric. The spray process was monitored for the dual purpose of (1) optimizing the process by maximizing silver deposition and minimizing fluid waste, thereby reducing suspension consumption and (2) assessing AgNPs release. Monitoring measurements were carried out at two locations: inside and outside the spray chamber (far field). We calculated the deposition efficiency (E), finding it to be enhanced by increasing the spray pressure from 1 to 1.5 bar, but to be lowered when the number of operating sprays was increased, demonstrating the multiple spray system to be less efficient than a single spray. Far-field AgNPs emission showed a particle concentration increase of less than 10% as compared to the background level. This finding suggests that under our experimental conditions, our spray-coating process is not a critical source of worker exposure.
ABSTRACT
In response to the nowadays battle against SARS-CoV-2, we designed a new class of high performant filter media suitable to advance the facemask technology and provide new efficient widespread solutions against virus propagation. By means of the electrospinning technology we developed filter media based on polyvinyl alcohol (PVA) nanofibers doped with AgNPs combining three main performance requirements: high air filtration efficiency to capture nanometer-size particles, low airflow resistance essential to ensure breathability and antimicrobial activity to inactivate aerosolized microorganisms. PVA/AgNPs electrospun nanofibers were produced by electrospinning the dispersion of colloidal silver into the PVA water solution. A widespread physicochemical characterization was addressed to the Ag colloidal suspension. The key functional performances of the electrospun nanofibers were proven by water stability, antibacterial activity, and filtration efficiency and pressure drop measurements performed under conditions representative of facemasks. We assessed a total bacterial depletion associated to a filtering efficiency towards nano-aerosolized particles of 97.7% higher than required by the EN149 standard and a pressure drop in line with FFP1 and FFP2 masks, even at the highest filtration velocity. Such results pave the way to the application of PVA/AgNPs electrospun nanofibers in facemasks as advanced filtering media for protecting against airborne microorganisms.