The enhancement of waste PET particles enzymatic degradation with a rotating packed bed reactor

Abstract

Polyethylene terephthalate (PET) is widely used, and biodegradation of waste PET results in a residue-free process, generating recyclable products, thereby contributing to the advancement of a more recyclable plastics lifecycle. Extensive research has been conducted on the modification and evolution of enzyme for PET degradation. As a solid-liquid heterogeneous reactions of PET degradation, the slow diffusion rate of the enzyme from liquid to solid PET surface leading to a slow reaction rate. Enhancement of mass transfer would accelerate PET degradation. Rotating packed bed (RPB) is a mass transfer enhancement reactor, but shear strength generated by the enzyme molecule knocking on rotator of RPB leads to enzyme denaturation. To address this issue, shear strength resistance agents were introduced in this study. With the protection of β-cyclodextrin combined with kieselguhr, PET particle degradation rate of 95% was achieved under the optimum conditions in 24 h, which was improved by 30% compared to that in stirred tank reactor. The results of this work demonstrated that the mass transfer greatly influenced the PET biodegradation process. RPB combined with the function of shear strength resistance agents could greatly improve the efficiency of the biodegradation process. This study provides a reference for the scaling up of PET degradation, and holds significant promise in the broader context of combatting plastic pollution challenges and advancing sustainable solutions for plastic waste.