Antimicrobial Nanofiber Based Filters for High Filtration Efficiency Respirators

Abstract

Electrospinning has been used to develop and upscale polyacrylonitrile (PAN) nanofibers as effective aerosol filtration materials for their potential use in respirators. The fibers were deposited onto non-woven spunbond polypropylene (SPP) and the basis weight (grammage, g/m2) was varied to assess the resulting effect on filtration efficiency and breathing resistance of the materials. The results indicated that a basis weight in excess of 0.4 g/m2 of PAN electrospun fibers yielded a filtration efficiency over 97%, with breathing resistance values that increased proportionally with the amount of basis weight added. With the aim of retaining filter efficiency whilst lowering breathing resistance, the basis weight of 0.4 g/m2 and 0.8 g/m2 of PAN electrospun fibers were strategically split up and stacked with SPP in different configurations. The results suggested that a symmetric structure based on SPP/PAN/PAN/SPP was the optimal structure, as it reduces SPP consumption while maintaining an FFP2-type of filtration efficiency, while reducing breathing resistance, specially at high air flow rates, such as those mimicking FFP2 exhalation conditions. The incorporation of zinc oxide (ZnO) nanoparticles within the electrospun nanofibers in the form of nanocomposites, retained the high filtration characteristics of the unfilled filter, while exhibiting a strong bactericidal capacity, even after short contact times. This study demonstrates the potential of using the symmetric splitting of the PAN nanofibers layer as a somewhat more efficient configuration in the design of filters for respirators.

Electrospun Nanofibre Filtration Media to Protect against Biological or Nonbiological Airborne Particles

“…The morphology of the NF layers shows a typical nonwoven stacking structure. The use of nanoscale fibres has proven to be advantageous in air filtration, since their small diameters and high surface-to-volume ratios can enhance the capture of particles through interception and other mechanisms [ 31 , 32 , 33 ]. It has also been shown that homogeneous porosity can result in lower pressure drop due to the slip flow effects of the NFs when compared with microfibre’s counterparts [ 34 ].…”

Electrospun Poly(ethylene Terephthalate)/Silk Fibroin Composite for Filtration Application

“…Different polymeric materials have been used for producing electrospun membrane for filtration including cellulose acetate (CA) [ 37 ], silk fibroin (SF) [ 38 ], poly(lactic acid) (PLA) [ 39 ], polyamide-6 (PA6), poly(vinyl alcohol) (PVA) [ 40 ], polyvinylacetate (PVAc) [ 37 ], polyacrylonitrile (PAN) [ 41 , 42 ], polyvinylidene fluoride (PVDF) [ 43 ], or poly(ethylene terephthalate) (PET) [ 33 , 44 ].…”

Antibacterial and Biodegradable Electrospun Filtering Membranes for Facemasks: An Attempt to Reduce Disposable Masks Use

“…Although membranes with higher thickness and basis weight are associated with higher filtration efficiency, they are also associated with higher breathing resistance [6,21]. Thus, a balance should be achieved to obtain the greatest filtration performance and breathability at the same time.…”

“…In fact, increasing the membranes' thickness provides more opportunities for the particles to meet with the fibers when they are traveling through the membrane [55]. Pardo-Figuerez et al also showed that the percentage of porosity of the electrospun membranes is reduced when a higher basis weight is deposited, which can also contribute to a decrease in breathability [6].…”

“…This technique enables the production of fibers with diameters ranging from micrometers to nanometers, which show significant morphological advantages over current conventional filters. Moreover, the cost effectiveness, simplicity of use, versatility of using different biodegradable natural or synthetic materials and possibility of scalability make electrospinning more competitive and attractive compared to conventional nonwoven manufacturing methods [5,6]. In fact, electrospun fibers exhibit outstanding properties, such as a high specific surface area, which results in the higher adsorption capacity of contaminants, controllable small diameters, highly porous structure with small pore sizes and internal interconnectivity, flexibility and possibility of functionalization with active agents.…”