Chemical recycling of Polyethylene terephthalate: A mini-review

Babaei, Mahsa; Jalilian, Milad; Shahbaz, Kaveh

doi:10.1016/j.jece.2024.112507

Cited by 6 publications

(4 citation statements)

References 152 publications

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“…These investigations have nevertheless demonstrated the proof-of-concept of the depolymerization of a range of biobased, biodegradable plastics. “Solvolysis” is a broad term which refers to the depolymerization of plastics due to the action of a solvent such as water (hydrolysis), an alcohol (alcoholysis), or glycol (glycolysis); with the latter usually applied to the recycling of PET [ 197 , 198 ]. Generally, the process consists of three main steps [ 168 ]: The reactant (either solvent or catalyst) diffuses through the bulk fluid to the plastic surface.…”

Section: Recycling Technologiesmentioning

confidence: 99%

Carbon Recycling of High Value Bioplastics: A Route to a Zero-Waste Future

Keith,

Koller,

Lackner

2024

Polymers

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Today, 98% of all plastics are fossil-based and non-biodegradable, and globally, only 9% are recycled. Microplastic and nanoplastic pollution is just beginning to be understood. As the global demand for sustainable alternatives to conventional plastics continues to rise, biobased and biodegradable plastics have emerged as a promising solution. This review article delves into the pivotal concept of carbon recycling as a pathway towards achieving a zero-waste future through the production and utilization of high-value bioplastics. The review comprehensively explores the current state of bioplastics (biobased and/or biodegradable materials), emphasizing the importance of carbon-neutral and circular approaches in their lifecycle. Today, bioplastics are chiefly used in low-value applications, such as packaging and single-use items. This article sheds light on value-added applications, like longer-lasting components and products, and demanding properties, for which bioplastics are increasingly being deployed. Based on the waste hierarchy paradigm—reduce, reuse, recycle—different use cases and end-of-life scenarios for materials will be described, including technological options for recycling, from mechanical to chemical methods. A special emphasis on common bioplastics—TPS, PLA, PHAs—as well as a discussion of composites, is provided. While it is acknowledged that the current plastics (waste) crisis stems largely from mismanagement, it needs to be stated that a radical solution must come from the core material side, including the intrinsic properties of the polymers and their formulations. The manner in which the cascaded use of bioplastics, labeling, legislation, recycling technologies, and consumer awareness can contribute to a zero-waste future for plastics is the core topics of this article.

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Section: Recycling Technologiesmentioning

confidence: 99%

Carbon Recycling of High Value Bioplastics: A Route to a Zero-Waste Future

Keith,

Koller,

Lackner

2024

Polymers

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“…3 To build a sustainable society in the future, methods to recycle or upconvert PET wastes with minimal environmental impact as much as possible will be necessary. 4 Recently, enzymatic methods of PET depolymerization have been proposed, 5 and PET-degrading enzymes have been actively developed for this purpose. 6 PET hydrolases have an α/β-hydrolase fold and have 6 helixes and 8 strands in the core structure.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Recently, enzymatic methods of PET depolymerization have been proposed, and PET-degrading enzymes have been actively developed for this purpose . PET hydrolases have an α/β-hydrolase fold and have 6 helixes and 8 strands in the core structure .…”

Section: Introductionmentioning

confidence: 99%

Direct Screening of PET Hydrolase Activity in Culture Medium Based on Turbidity Reduction

Ogura,

Hashino,

Nakamura

2024

ACS Omega

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The development of an efficient screening method for the activity of PET-degrading enzymes represents a significant technological advance in the field of enzyme research, with the potential to facilitate the advancement of enzymes for PET recycling. By examining the stable conditions of PET suspension and enzyme production conditions, we developed a method to quantify PET-degrading enzyme activity in E. coli culture medium using turbidity reduction as an indicator. High PET concentration or ionic strength caused aggregation of PET, and the best condition for activity detection was 0.5 mg mL–1 PET in 50 mM sodium phosphate pH 7.0. Preculture of E. coli increased the purity of enzyme secreted in medium. To evaluate the screening method, 720 colonies of the PET2-7M-H229X-F233X mutant library were analyzed and three candidates of high-activity mutants were obtained. The thermostability of the mutants could also be easily measured by measuring the residual activity after heat treatment. The H229T-F233M mutant showed 3.4 times higher degradation rate against PET film than the template enzyme at the initial time. The molecular dynamics simulation implied that the F233M mutation makes space for making an α helix and that the H229T mutation resolved the steric hindrance with Trp199. These mutations were speculated to change the angle of the Trp199 side chain of PET2 to an angle similar to that of the Trp185 of IsPETase, making it suitable for PET binding to the active center. Screening of activity using PET suspensions is compatible with robotic automation and is expected to be useful for validating computationally predicted mutations.

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“…Tertiary recycling includes chemical methods [10]. First of all, chemical recycling includes methods based on the reactions of the ester group in the polyethylene terephthalate chain.…”

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confidence: 99%

Polyethylene Terephthalate Waste Forms: Going beyond Flakes and Fibers

Kirshanov,

Toms,

Aliev

et al. 2024

Preprint

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There are various approaches to managing polyethylene terephthalate waste, including methods for recycling PET. However, at present, only the cleanest wastes that can already be efficiently recycled using known methods are considered in the scientific literature. The study aims to look at other forms of polyethylene terephthalate waste that pose a challenge: low quality PET flakes, polyester tire cord, PET dust and prepolymer waste. The waste was characterized by FTIR spectroscopy, viscosimetry, differential scanning calorimetry, laser diffraction and sieve analysis. The findings describe the composition and properties of various forms of polyethylene terephthalate waste. Low quality PET flake waste and polyethylene terephthalate dust have been shown to be suitable for all chemical recycling methods. When recycling waste polyester tire cord, it is difficult to completely separate the rubber, so its presence in the final product must be taken into account. The most promising way to process a prepolymer is its depolymerization by hydrolysis, alcoholysis or glycolysis to produce monomers for the synthesis of PET, similar in properties to the primary one.

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Chemical recycling of Polyethylene terephthalate: A mini-review

Cited by 6 publications

References 152 publications

Carbon Recycling of High Value Bioplastics: A Route to a Zero-Waste Future

Carbon Recycling of High Value Bioplastics: A Route to a Zero-Waste Future

Direct Screening of PET Hydrolase Activity in Culture Medium Based on Turbidity Reduction

Polyethylene Terephthalate Waste Forms: Going beyond Flakes and Fibers

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