Closed-loop recycling of PET fabric and bottle waste by tandem pre-amorphization and enzymatic hydrolysis

Abstract

Pre-consumer PET fabric scraps and post-consumer PET bottles, two common PET waste streams, are difficult to break down by the reported PET hydrolases. Our findings indicate that the lack of cold crystallization enthalpy (ΔH_c) is a key factor determining their low enzymatic degradability. Melt-quenching pre-treatment, with 0 °C water as the most effective quenching medium, can successfully raise ΔH_c in PET fabrics and bottles. Pre-amorphized PET fabrics and bottles showed a 54- and 404-fold increase in conversion rate by the LCC^ICCG enzyme as compared to their pristine counterparts, respectively. The technical-economic feasibility and energy effectiveness of the tandem pre-amorphization and enzymatic hydrolysis strategy for recycling pre-consumer PET fabric scraps and post-consumer PET bottles were assessed by constructing a kilogram-scale process, respectively. The results indicate that this efficient, energy-saving, and cost-effective method has greater economic potential for recycling pre-consumer PET fabric scraps than post-consumer PET bottles.