Ultraviolet Ozone Pretreatment Enhances selective PETase Biodegradation of Textiles Compared to Sunlight and Alkali Treatments.

Abstract

The rapid growth of the fashion industry has led to increasing textile waste, exacerbating environmental pollution and climate change. To support sustainability and circular economy goals, this study investigates the enzymatic degradation of cotton/polyethylene terephthalate (PET) mixed textiles using PETase, comparing wild-type (WT) and mutant (MUT S238F/W159H) variants. To improve enzyme accessibility, we evaluated three pretreatment strategies: alkali treatment, ultraviolet-ozone (UVO) exposure, and natural sunlight weathering. The effects were assessed by measuring textile weight loss, surface morphology (SEM), infrared spectroscopy (FTIR), and yields of terephthalic acid (TPA) and mono-(2-hydroxyethyl) terephthalic acid (MHET). Alkali treatment produced the highest weight loss, while UVO pretreatment moderately degraded textiles and significantly enhanced enzymatic TPA production. In contrast, prolonged sunlight exposure had negligible effects. ^1H NMR analysis of supernatants confirmed the formation of oxidized PET products following UVO exposure, indicating surface chemical modifications that increase enzymatic susceptibility. Our results reveal differential effects on PET and cotton fibers, highlighting UVO as a promising, selective pretreatment for mixed textile waste. This study demonstrates the potential of combining photochemical oxidation and enzymatic processes for targeted PET degradation, contributing to more efficient textile recycling strategies.