Green Chemical Approaches for Upcycling Waste Polyester/Cotton Blends into Antibacterial Cellulose Films and Recovered TPA

The rapid development of the textile industry has led to massive disposal of waste polyester/cotton blended fabrics via landfilling or incineration, causing severe environmental pollution and resource waste. To achieve high-value recycling, this work proposes a green chemical approach for efficient separation and upcycling of polyester and cotton components. A deep eutectic solvent (ZnCl₂/H₃PO₄/H₂O) dissolved cotton, leaving polyester intact. The cellulose solution, rich in Zn²⁺ ions, was reinforced with bacterial cellulose (BC) to form a composite film. Subsequent NaOH treatment and thermal decomposition enabled in situ synthesis of zinc oxide (ZnO), yielding an antibacterial regenerated cellulose film (Cellulose/BC/ZnO). Antibacterial tests showed that the inhibition zones against E. coli, S. aureus, and P. aeruginosa were 2.6 ± 0.2, 3.0 ± 0.2, and 2.0 ± 0.2 mm, respectively, confirming the antibacterial efficacy of zinc oxide. For separated polyester fibers, a bio-based solvent system (DMI/EG/KOH) facilitated alkaline hydrolysis, depolymerizing PET into high-purity terephthalic acid (TPA). Structural and thermal analyses (FT-IR, XRD, TGA) verified TPA recovery. Molecular dynamics simulations elucidated solvent-polymer interactions at the electronic level, offering mechanistic insights into cellulose dissolution and PET depolymerization. This work provides a sustainable strategy for textile waste upcycling, expands applications of regenerated cellulose films in biomedicine, and promotes closed-loop polyester recycling.