Closed-loop recycling of polyester-cotton blended fabrics through dissolution-precipitation pretreatment and enzymatic depolymerization

Recycling of waste polyester-cotton blended fabrics (PCB) is confronted with challenges due to the different chemical properties of each component and their intertwined structure. Herein, PCBs were degraded into monomers through room-temperature dissolution-precipitation pretreatment and enzymatic depolymerization. Polyester was selectively dissolved and separated from PCB and then precipitated in anti-solvent. The influence of the dissolved PET concentration on the recovery, particle size, and crystallinity of precipitated PET was investigated. The precipitated PET exhibited nanometer size and low crystallinity of 7.8%, which significantly accelerated the enzymatic depolymerization. The separated cotton fibers from PCB were also enzymatically depolymerized into glucose. At last, real-world PCBs with different component ratios and colors were successfully converted through this approach. This research provides a promising method for closed-loop recycling of PCB wastes.