Ultra‐Fine Electroblown Nanofibrous Air Filters Produced From Recycled Textile Polyester Waste: Process Optimization and Electret Stability

ABSTRACT Textile‐derived recycled polyester (rPET) cutting wastes are an abundant yet underutilized resource with limited high‐value applications. This study demonstrates an upcycling strategy to convert low‐value rPET shoddy and trimming residues into ultra‐fine nanofibrous air filtration media via electroblowing. A three‐factor response surface methodology (Box–Behnken design, 23 runs) was applied to optimize polymer concentration (7–13 wt.%), air pressure (0.5–3.5 bar), and feeding rate (2–10 mL/h) with respect to fiber diameter. The quadratic model showed strong predictive capability (R 2 = 97.53%), identifying concentration as the dominant parameter and revealing a non‐linear thinning regime at low concentration. Under optimized conditions (≈7.75 wt.%, 3.5 bar, 2 mL/h; 30 kV, 30 cm), bead‐free nanofibers with a mean diameter of 41 ± 14 nm were produced. Filtration performance evaluated using NaCl aerosols (0.26 ± 0.07 µm, 95 L/min) demonstrated a clear diameter–performance relationship. The ultra‐fine sample exhibited high efficiency with moderate pressure drop, while corona treatment further enhanced performance, achieving up to 99.995% efficiency and improving the quality factor by 37%. Electret lifetime tests revealed minimal efficiency decay over one month, particularly for finer fibers. Overall, this work establishes a scalable electroblowing route for converting rPET waste into high‐performance air filters.