What is the role of hydrogen peroxide (H₂O₂) in the photodegradation of polyethylene terephthalate (PET) and its monomers bis(2-hydroxyethyl)terephthalate (BHET) and terephthalic acid (TPA)?
Label:chem
Topic
Hydrogen peroxide (H₂O₂) is used as an oxidizing agent in Advanced Oxidation Processes (AOPs) to generate highly reactive hydroxyl radicals (·OH) that can degrade organic pollutants. In this study, H₂O₂ is combined with UV radiation from excimer lamps (KrCl at 222 nm and XeBr at 283 nm) to enhance the degradation of PET-derived compounds.
Answer
Hydrogen peroxide plays a crucial role in the photodegradation process by providing hydroxyl radicals necessary for the degradation of BHET and TPA. The study found that the optimal H₂O₂/monomer mass ratios were 3:1 for TPA and 4:1 and 5:1 for BHET with XeBr and KrCl lamps, respectively. Exceeding these ratios led to reduced efficiency due to hydroxyl radical scavenging. The presence of H₂O₂ significantly enhanced the degradation rates, achieving near-complete conversion of TPA and BHET under optimal conditions.
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