Polyethylene terephthalate plastic (PET) is one of the most extensively used materials worldwide because it is affordable, lightweight, and extremely durable. A proper end-of-life management is essential, in order to meet growing environmental concerns. In recent years, there has been an increasing focus on the chemical breakdown and recycling of PET materials, whose primary goal is the recovery of the polymer components (monomers) that are used to create PET, namely ethylene glycol and the more expensive terephthalic acid. Such compounds can be used to synthesize again the virgin polymer, resulting in a complete recycling of the original waste. Zn2+ ions have been shown to catalyze PET hydrolysis by attacking the carbonyl group as Lewis acid as described in the reaction in Figure 1. This reaction yields the starting PET monomer but requires high temperature and a long reaction time (180 ° C 24 h)1, making it economically non-viable for PET waste recycle. In this work, we present a new approach, based on the use of a deep eutectic solvent (DES) composed of ZnCl2 and urea in 1:3.5 molar ratio. The outcome is an onset of depolymerization of post-commercial PET flakes in a microwave oven, occurring already in less than 5 minutes. To gain insight into the process, the resulting depolymerization products are characterized by FTIR-ATR and XRD measurements.

PET depolymerization using Zn2+ based DES

Bauer, Elvira Maria;
2024

Abstract

Polyethylene terephthalate plastic (PET) is one of the most extensively used materials worldwide because it is affordable, lightweight, and extremely durable. A proper end-of-life management is essential, in order to meet growing environmental concerns. In recent years, there has been an increasing focus on the chemical breakdown and recycling of PET materials, whose primary goal is the recovery of the polymer components (monomers) that are used to create PET, namely ethylene glycol and the more expensive terephthalic acid. Such compounds can be used to synthesize again the virgin polymer, resulting in a complete recycling of the original waste. Zn2+ ions have been shown to catalyze PET hydrolysis by attacking the carbonyl group as Lewis acid as described in the reaction in Figure 1. This reaction yields the starting PET monomer but requires high temperature and a long reaction time (180 ° C 24 h)1, making it economically non-viable for PET waste recycle. In this work, we present a new approach, based on the use of a deep eutectic solvent (DES) composed of ZnCl2 and urea in 1:3.5 molar ratio. The outcome is an onset of depolymerization of post-commercial PET flakes in a microwave oven, occurring already in less than 5 minutes. To gain insight into the process, the resulting depolymerization products are characterized by FTIR-ATR and XRD measurements.
2024
Istituto di Struttura della Materia - ISM - Sede Secondaria Montelibretti
PET
depolymerization
DES
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/520440
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