Enzymatic post-consumer poly(ethylene terephthalate) (PET) depolymerization using commercial enzymes

Area of Science:

• Biotechnology
• Polymer Science
• Environmental Science

Background:

• Poly(ethylene terephthalate) (PET) is a widely used synthetic polymer with poor biodegradability, leading to environmental accumulation.
• Improper disposal of PET plastic poses significant threats to terrestrial and aquatic ecosystems.

Purpose of the Study:

• To investigate the enzymatic degradation of post-consumer PET (PC-PET) using various hydrolase enzymes.
• To identify the most effective enzyme and optimize reaction conditions for PC-PET hydrolysis.

Main Methods:

• Screening of five commercial hydrolase enzymes for PC-PET degradation activity.
• Evaluation of key reaction parameters including enzyme type, concentration, temperature, and ultrasound treatment using Humicola insolens cutinase (HiC).
• Analysis of hydrolysis products: terephthalic acid (TPA), mono(2-hydroxyethyl) terephthalate (MHET), and bis(2-hydroxyethyl) terephthalate (BHET).

Main Results:

• Humicola insolens cutinase (HiC) demonstrated the highest activity among the tested enzymes.
• Reaction temperature significantly influenced the yield and ratio of hydrolysis products, with higher temperatures favoring TPA formation.
• Enzymatic hydrolysis was highly sensitive to enzyme concentration, with optimal results observed at 40-50 vol % HiC.

Conclusions:

• Enzymatic hydrolysis using HiC is a promising method for PC-PET degradation.
• Optimizing temperature and enzyme concentration is crucial for efficient PET recycling.
• The findings contribute valuable data for advancing enzyme-based plastic recycling technologies.