Silver nanodot embedded waste PET nanofibres for efficient multifunctional air filter

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.