rPET Nanofiber Membranes for Air Filtration: High Performance via Electrospinning Optimization

Although recycled poly(ethylene terephthalate) (rPET) is an attractive, sustainable feedstock for electrospinning, optimization of processing variables for filtration performance remains limited. This study quantifies how polymer concentration, flow rate, and applied voltage govern fiber morphology and key filtration metrics—collection efficiency (η), pressure drop (ΔP), quality factor (Qf), and porosity—in rPET membranes. A fractional factorial design was employed to model interactions and identify trade-offs in filtration performance. The optimal condition was obtained at 16 wt.% PET, 1.2 mL·h−1, and 22 kV, yielding uniform fibers with an average diameter of 328.6 nm and high filtration efficiencies (95.65–99.99%). The permeability constants were 1.07 × 10−12 m2 (20 wt.% PET) and 1.15 × 10−13 m2 (8 wt.% PET), indicating an increase in permeability with increasing polymer concentration and fiber diameter. The 20 wt.% PET membrane delivered the highest Qf of 0.0646 Pa−1 with a low ΔP of 48.5 Pa at 4.8 cm·s−1, reflecting a favorable balance between collection and airflow resistance. In summary, higher PET concentrations reduce flow resistance and improve Qf, whereas lower concentrations yield finer fibers and high η at the expense of permeability. rPET nanofiber membranes, therefore, represent a sustainable and versatile route to high-efficiency, lower-pressure-drop air filters for residential, industrial, and commercial environments.