abstract
While (bio)degradation of polymers is a recognized challenge, the influence of additives on this process remains poorly understood. Their presence in commercial polyethylene (PE) may inhibit the degradation process or complicate the recycling. This study aims to develop an enzymatic degradation process for post-consumer highdensity polyethylene (HDPE). The HDPE degradation was performed using laccase from Trametes versicolor under mild conditions of temperature and pressure. The process was developed by exploring three key conditions: (i) the biocatalytic medium; (ii) the enzymatic mediator, and (iii) the influence of the presence of additives in the polymers. The most successful enzymatic degradation system involved HDPE from which additives were removed, with a buffer used as the reaction medium and 2,2 '-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) employed as the enzymatic mediator. This system led to a substantial 33% weight reduction of the polymer (versus 3% for HDPE with additive under the same conditions). The characterization of the degraded polymer revealed new bands in the Fourier transform infrared spectroscopy (FTIR) spectra, including a new carbonyl band. In addition, it also showed an increased crystallinity when compared to HDPE with additive under the same conditions. These results suggest that the enzymatic degradation of HDPE occurs through an oxidation process, with the enzyme preferentially attacking the amorphous region of the polymer.
keywords
POLYETHYLENE; LACCASE; MIGRATION; SYSTEMS
subject category
Chemistry; Engineering
authors
Aguiar, MIS; Sousa, AF; Teixeira, G; Tavares, APM; Ferreira, AM; Coutinho, JAP
our authors
Ana Maria da Conceição Ferreira Takahashi
Junior Researcher
Ana Paula Mora Tavares
Assistant Professor
Andreia Fernandes de Sousa
Principal Researcher
Gabriel Teixeira Santos
PhD Student
Groups
G4 - Renewable Materials and Circular Economy
G5 - Biomimetic, Biological and Living Materials
Projects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
European network of FURan based chemicals and materials FOR a Sustainable development (FUR4Sustain)
acknowledgements
This work was partly developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MCTES (PIDDAC) . MISA and GT acknowledge FCT for the Ph.D. grants PRT/BD/154714/2023 and UI/BD/151141/2021, respectively. AFS, APT and AMF acknowledge FCT for the research contracts CEECIND/02322/2020, CEECIND/01867/2020, and CEECIND/00361/2022 respectively. This publication is supported by COST Action FUR4Sustain-European network of FURan based chemicals and materials FOR a Sustainable development, CA18220, supported by COST (European Cooperation in Science and Technology) .