Needleless electrospinning for scaled-up production of ultrafine chitosan hybrid nanofibers used for air filtration

Large scale ultrafine chitosan hybrid nanofibers containing TiO2 and/or Ag nanoparticles were prepared using a needleless electrospinning method. The nanofiber production rate reached 50 g h(-1) using the needleless electrospinning method, which was much higher than 0.02-1 g h(-1) in the traditional single needle electrospinning method. By optimizing the spinning parameters, nanofibers with a smooth uniform morphology were obtained with diameters ranging from 25 to 60 nm and Ag nanoparticles with an average size of 2.9 nm were deposited on the surface of the nanofibers without aggregation. The hybrid nanofibers exhibited a significant increase in filtration efficiency (>99%) for removal of nanoparticle aerosols, comparable to commercial high-efficiency particulate air filters, but with a lower pressure drop and less mess. The chitosan hybrid nanofibers showed excellent antibacterial activity, e.g. 97% of E. coli and 99% of S. aureus were killed within 2 h. The cross-linked nanofibers exhibited excellent water durability and maintained a stable microstructure in high humidity and in water immersion. Daily productivity can be above 1.2 kg, which makes these ultrafine nanofibers suitable for the application of wound dressing, air filtration and environmental purification.