Sustainable upcycling of waste PET fabrics into Superhydrophilic materials for high-efficiency oil-water separation.

Oily wastewater poses a severe threat to aquatic ecosystems and public health, while the massive accumulation of waste polyester (PET) textiles exacerbates environmental pollution. To address these challenges, we developed a sustainable approach for transforming discarded PET fabrics into functional materials for efficient oil-water separation. A superhydrophilic modification layer was constructed on PET surfaces via co-deposition of polydopamine (PDA) and polyethyleneimine (PEI). Under optimized conditions (PDA/PEI mass ratio = 1:1, deposition time = 24 h), the modified PET fabric exhibited exceptional superhydrophilicity (water contact angle = 0°) and underwater superoleophobicity (oil contact angle = 161.9°). The material demonstrated robust chemical stability, maintaining >97 % separation efficiency and a stable flux of (20,570.89 ± 1213.74) L·m-2·h-1 across a wide pH range (2-12). It achieved high separation efficiencies (>98.3 %) for various oils (n-hexane, dichloromethane, and isooctane) and retained >98 % efficiency after 10 reuse cycles in neutral medium. This work presents a simple yet effective strategy for upcycling waste PET into high-performance oil-water separation materials, offering a sustainable solution for environmental remediation and resource recovery.