Silver nanodot embedded waste PET nanofibres for efficient multifunctional air filter.

Abstract

This study focuses on conversion of waste polyethylene terephthalate (PET) into ultrafine nanofibres with silver nanodots (AgND) (diameter 3.49 ± 0.94 nm) embedded within via electrospinning. Ultrafine PET (diameter 74 ± 15 nm) or PET-AgND (diameter 68 ± 17.4 nm) nanofibre-based membranes (basis weight 0.5 ± 0.02 g/m², thickness 20 ± 1.4 μm), sandwiched between two spun-bond nonwoven layers, achieved a remarkable particle filtration efficiency (PFE) of 99.24-99.93% against 10-1000 nm particles, while maintaining pressure drop (ΔP) of 13 Pa at a face velocity of 5 cm/s. Such 3-ply filters demonstrated PFE > 99.5% against 350 nm particles with ΔP between 13-27 Pa over 28 consecutive filtration cycles. The PET-AgND membranes also demonstrated antibacterial efficacy of 99.78 ± 0.18% against Escherichia coli and 99.92 ± 0.02% against Staphylococcus aureus, respectively. Washability assessments showed reduction of PFE from 99.7% to 57.6% with increment in pressure drop from 13 to 79 Pa, from unwashed till 9 washing-drying trials. The 3-ply filters also exhibited significant air permeability (64.4 ± 0.25 cm³/cm²-s), water vapor transmission rate (82.45 ± 2.7 g³/m²-h) coupled with prominent UV protection (79.5%). This study highlights a sustainable route for converting waste PET into high-performance, multifunctional, filter media.