Recycling of polyethylene terephthalate wastes: A review of technologies, routes, and applications

Suhaimi, Nur Aina Syafiqah; Muhamad, Farina; Razak, Nasrul Anuar Abd; Zeimaran, Ehsan

doi:10.1002/pen.26017

Cited by 70 publications

(46 citation statements)

References 124 publications

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“…The technique is fairly well-established and has been scaled for PET recycling in many countries. Mechanical recycling is an important technology and has enabled a dramatic increase in the amount of material that is found in closed-loop, bottle-to-bottle applications . Mechanical recycling, especially for polyolefins, has a risk of resulting in material with inferior properties compared with the original application. − The typical melt reprocessing involved can lead to degradation of chains, lowering of molar mass, and consequently poor suitability for remolding after several reuse cycles.…”

Section: Recycling Strategies and End-of-life For Petmentioning

confidence: 99%

Trends in Polyester Upcycling for Diversifying a Problematic Waste Stream

2023

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We are facing a rapidly growing plastic pollution crisis, which is adversely affecting communities and ecosystems across the globe. Polymer scientists have an urgent obligation to develop and implement strategies for reutilizing plastic waste streams instead of continually relying on virgin feedstocks in plastic manufacturing. Postconsumer and postindustrial plastic items should be treated as valuable resources instead of discarding them. In order to do this, technological outlets must be developed to produce renewed materials using plastic waste as an input. Polyesters represent one of the largest plastic waste streams because they are commonly used in single-use beverage and food containers as well as textiles. Polyesters are also ideal candidates to exploit through chemical diversification, owing to the wide variety of functional derivatives that can be synthetically accessed via ester reactivity. This work highlights some recent developments related to diversifying polyester waste, with a focus on poly(ethylene terephthalate) (PET) as waste stream. The strategies encompass the production of both valuable small molecules prepared via degradation of PET and high-performance polymeric scaffolds derived from reactions with PET. Taking the recent ingenuity into consideration, based on these technological developments, an outlook is provided for the future of polyester waste streams. What are the next steps that are needed? Where are these trends headed? What gaps still exist, particularly with respect to assessment of sustainability and life cycle analysis? Collectively considering the examples highlighted here, there is great promise in the field of reutilizing waste streams as feedstocks for value-added materials.

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Section: Recycling Strategies and End-of-life For Petmentioning

confidence: 99%

Trends in Polyester Upcycling for Diversifying a Problematic Waste Stream

2023

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“…Both mechanical and chemical recycling strategies for PET are currently implemented on industrial level; the obtained recycled PET (rPET) is used in various applications [ 53 ]. In relation to the topic of this review, it is important to note that chemical recycling of PET in sc methanol is a rare example of a supercritical fluid recycling process for which industrial implementation has been carried out: a pilot plant for PET methanolysis was launched by Mitsubishi Heavy Industries, Ltd. (Japan).…”

Section: Recycling Of Polysiloxanes In Supercritical Mediamentioning

confidence: 99%

Chemical Recycling of High-Molecular-Weight Organosilicon Compounds in Supercritical Fluids

et al. 2022

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The main known patterns of thermal and/or catalytic destruction of high-molecular-weight organosilicon compounds are considered from the viewpoint of the prospects for processing their wastes. The advantages of using supercritical fluids in plastic recycling are outlined. They are related to a high diffusion rate, efficient extraction of degradation products, the dependence of solvent properties on pressure and temperature, etc. A promising area for further research is described concerning the application of supercritical fluids for processing the wastes of organosilicon macromolecular compounds.

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“…In total, more than 8.3 billion tons of plastic have been produced since the early 1950s and approximately 60% ended up in landfills [ 1 , 2 ]. The largest groups of plastics include polyethylene (36%), polypropylene (21%), polyvinylchloride (12%), poly(ethyleneterephthalate) (PET), polyurethane, and polystyrene (<10% each) [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

Optimization and Kinetic Evaluation for Glycolytic Depolymerization of Post-Consumer PET Waste with Sodium Methoxide

2023

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Glycolysis of post-consumer polyethylene terephthalate (PET) waste is a promising chemical recycling technique, back to the monomer, bis(2-hydroxyethyl) terephthalate (BHET). This work presents sodium methoxide (MeONa) as a low-cost catalyst for this purpose. BHET product was confirmed by gas chromatography-mass spectrometry (GCMS), Nuclear Magnetic Resonance (NMR) Spectroscopy, melting point, and Differential Scanning Calorimetry (DSC). It was shown, not surprisingly, that PET conversion increases with the glycolysis temperature. At a fixed temperature of 190 °C, the response surface methodology (RSM) based on the Box-Behnken design was applied. Four independent factors, namely the molar ratio of PET: MeONa (50–150), the molar ratio of ethylene glycol to PET (EG: PET) (3–7), the reaction time (2–6 h), and the particle size (0.25–1 mm) were studied. Based on the experimental results, regression models as a function of significant process factors were obtained and evaluated by analysis of variance (ANOVA), to predict the depolymerization performance of MeONa in terms of PET conversion. Coefficient of determination, R2 of 95% indicated the adequacy for predicted model. Afterward, the regression model was validated and optimized within the design space with a prediction of 87% PET conversion at the optimum conditions demonstrating a deviation of less than 5% from predicted response. A van ‘t Hoff plot confirmed the endothermic nature of the depolymerization reaction. The ceiling temperature (TC = 160 °C) was calculated from Gibbs’ free energy. A kinetic study for the depolymerization reaction was performed and the activation energy for MeONa was estimated from the Arrhenius plot (EA = 130 kJ/mol). The catalytic depolymerization efficiency of MeONa was compared under similar conditions with widely studied zinc acetate and cobalt acetate. This study shows that MeONa’s performance, as a glycolysis catalyst is promising; in addition, it is much cheaper and environmentally more benign than heavy metal salts. These findings make a valuable contribution towards the chemical recycling of post-consumer PET waste to meet future recycling demands of a circular economy.

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Recycling of polyethylene terephthalate wastes: A review of technologies, routes, and applications

Cited by 70 publications

References 124 publications

Trends in Polyester Upcycling for Diversifying a Problematic Waste Stream

Trends in Polyester Upcycling for Diversifying a Problematic Waste Stream

Chemical Recycling of High-Molecular-Weight Organosilicon Compounds in Supercritical Fluids

Optimization and Kinetic Evaluation for Glycolytic Depolymerization of Post-Consumer PET Waste with Sodium Methoxide

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