China News Network, Hefei, June 10 (Reporter Wu Lan) Professor Fu Yao and associate researcher Deng Jin of the University of Science and Technology of China, together with Professor Li Shen of Utrecht University in the Netherlands, recently reported a plan to upgrade and recycle waste PET plastics.

The relevant results were published in Nature Communications.

PET plastic has brought great convenience to human life, but it also faces problems such as high total consumption and difficulty in recycling. Through the current mature PET recycling methods, it is possible to achieve degraded recycling from waste beverage bottles to polyester textiles. However, due to limitations in process technology and production costs, it is currently difficult to achieve circular recycling and upgraded recycling in industry.

Researchers used acetic acid to depolymerize waste PET plastics, and the depolymerization of PET in organic acids underwent a melting dissolution precipitation process. Through this scheme, efficient recovery of various waste PET materials directly into high-purity terephthalic acid has been achieved. Another product of PET acetic acid depolymerization is the third generation environmentally friendly strong solvent ethylene glycol diacetate with high added value. The preparation scheme of acetic acid depolymerization waste PET material also has strong economic appeal for the production of commonly used industrial raw materials such as terephthalic acid and ethylene glycol diacetate.

On this basis, the researchers put forward the technical scheme of "depolymerization polymerization regeneration of waste PET acetic acid" closed-loop cycle, and conducted a Life-cycle assessment of the process.

The results show that compared with the process of preparing PET polyester from fossil resources, the energy consumption of Non-renewable resource and global warming potential of this process can be reduced by more than 70% and 40% respectively, which is the lowest environmental impact among all PET chemical recovery methods at present.

This study provides a new approach for achieving a closed-loop cycle of waste PET plastic and polyester fabric, with lower industrial costs, strong economic appeal, greener and low-carbon treatment processes, and stronger tolerance to raw material sources.

The scientific research team has preliminarily implemented kilogram scale engineering experiments, and at the beginning of the experimental design, acetic acid, a solvent currently used for industrial production of terephthalic acid, was selected as the solvent for decomposing waste polyester, fully drawing on current production equipment and process parameters.

It is reported that the research results can be quickly verified and promoted through relatively simple modifications based on existing industrial equipment.