Recycling of full components of polyester/cotton blends catalyzed by betaine-based deep eutectic solvents

The development of an environmental methodology for polyethylene terephthalate (PET) degradation and separation from cotton is significant for the full utilization of waste polyester/cotton blends (PCBs). Therefore, it is crucial to find a catalyst that can efficiently catalyze PET degradation and completely separate from cotton. In this work, betaine based deep eutectic solvents (DESs) were first synthesized and innovatively used for selective degradation of PET fibers from PCBs. As a result, PET fiber was degraded completely, a purified monomer bis (2-hydroxyethyl terephthalate) (BHET) with a yield of 85% was obtained that could be repolymerized to produce PET, and 95% of the cotton was recycled and maintained its original structural integrity. Meanwhile, the synergistic mechanism was also proposed by in-situ IR, H-1-NMR and DFT calculations. This work provides a new approach to recycle full components of waste PCBs.

Automated summary

The development of an environmental methodology for PET degradation and separation from cotton is important for utilizing waste polyester/cotton blends. In this study, a betaine based deep eutectic solvent was used to selectively degrade PET fibers, resulting in purified monomer for PET repolymerization and high cotton recovery.