Tunable fabrication of three-dimensional polyamide-66 nano-fiber/nets for high efficiency fine particulate filtration

A novel airborne particulate filtration medium, consisting of a two-tier composite structure, i.e., a nano-fiber/net (NFN) top layer and a conventional nonwoven microfibrous support, was demonstrated for highly efficient and low pressure drop filtration for the first time. The polyamide-66 (PA-66) NFN structured top layer, which is composed of traditional electrospun nanofibers and two-dimensional (2D) spider-web-like nano-nets, was electro-spinning/netting (ESN) deposited on the nonwoven polypropylene (PP) scaffold for constructing this new concept of filter. The morphology of NFN architecture, including fiber diameter, coverage rate, pore-width and layer-by-layer packing structure of the nano-nets, can be finely controlled by regulating the solution properties and several ESN process parameters. Taking advantage of several fascinating features such as extremely small diameter, high porosity, controllable coverage rate, nano-nets bring to the NFN/nonwoven composite filtration medium several excellent filtration features such as high filtration efficiency (up to 99.9%), low pressure drop, facile filters cleaning, and more lightweight.