Morphological Engineering of Electrospun Recycled Polyethylene Terephthalate (r-PET) Nanofibrous Membranes for Sustainable Air Filtration: A Critical Review

The growing demand for high-performance air filtration materials, coupled with increasing concerns over plastic waste accumulation, has accelerated interest in sustainable filtration technologies. Recycled polyethylene terephthalate (r-PET) has emerged as a promising feedstock for electrospun nanofibrous membranes due to the abundance, low cost, and sustainability of this plastic waste feedstock. The filtration performance of r-PET membranes has been demonstrated to be comparable to that of conventional virgin polymer filters. This review critically examines recent developments in electrospun r-PET nanofibrous membranes for air filtration applications, with particular emphasis on the role of membrane morphology in governing filtration performance. Unlike previous reviews that primarily summarize electrospinning techniques or recycled polymer applications, this review critically evaluates how membrane morphology—including fiber diameter, pore architecture, bead-on-string structures, and multilayer configurations—governs filtration performance in electrospun r-PET membranes. Evidence suggests that rational morphological engineering plays a more decisive role than polymer chemistry in overcoming the conventional filtration efficiency–pressure drop trade-off. Finally, future research opportunities in scalable manufacturing, environmentally benign processing, and artificial intelligence-assisted membrane design are discussed to support the development of next-generation sustainable air filtration media.