One-pot co-ethanolysis of polyester/cotton blends to diethyl terephthalate and ethyl levulinate catalyzed by an acidic ionic liquid

Novel co-ethanolysis enables one-pot depolymerization of PET and cotton. • Results suggest a possible bifunctional swelling–catalysis synergy. • 48.7% EL yield and 90.7% DET yield. • LCA and TEA indicate favorable energy, carbon, and cost performance. To address the key bottlenecks in poly(ethylene terephthalate) (PET)/cotton textile recycling—namely, separation difficulty, high energy consumption, and low product value—this study developed an ionic liquid [Hnmp]HSO 4 /ethanol system for the conversion of PET and cotton into high-value chemicals, diethyl terephthalate (DET) and ethyl levulinate (EL), enabling simultaneous ethanolysis of both cotton and PET without sorting. The results suggest that the [Hnmp] + cation may interact with cotton and PET through its lactam carbonyl group, potentially promoting substrate swelling and structural disruption, while the HSO 4 − anion provides Brønsted acid sites for ethanolysis. This proposed swelling–catalysis synergy may contribute to the superior catalytic performance of [Hnmp]HSO 4 compared with conventional acid catalysts. Under optimized conditions, the PET conversion reached 95.6%, with a DET yield of 90.7%, and the cotton was converted to EL with a yield of 48.7%. The system exhibited good adaptability across different PET/cotton (P/C) blend ratios. Life cycle assessment (LCA) indicated a reduction of approximately 30–34% in NREU and GWP relative to the modeled Ni–ZnO/Al 2 O 3 –HPWV reference route. Techno-economic analysis (TEA) further indicated the economic feasibility and scale-up potential of the process at an assumed processing capacity of 1000 t year −1 . This work provides a potentially cost-effective and environmentally sustainable pathway for the valorization of mixed textile waste. Download: Download high-res image (184KB) Download: Download full-size image