Towards closed-loop recycling of multilayer and coloured PET plastic waste by alkaline hydrolysis

Üǧdüler, Sibel; Geem, Kevin Van; Denolf, Ruben; Roosen, Martijn; Mys, Nicolas; Ragaert, Kim; Meester, Steven De

doi:10.1039/d0gc00894j

Cited by 297 publications

(188 citation statements)

References 49 publications

(52 reference statements)

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“…Thermal recycling approaches (such as, hydrogenolysis 13 and glycolysis 14 ) lead to the recovery of monomers (terephthalic acid (PTA) or bis(2‐hydroxyethyl) terephthalate) under elevated temperatures. The polyester nature of PET makes it readily decomposed into its monomers under mild conditions catalyzed by base 2 , 11 or hydrolases 10 , which can be further transformed into valuable products. Recently, Erwin and co-workers reported a photoreforming strategy for converting PET waste into clean H 2 fuel and oxygenates (i.e., formate, glyoxal, and acetate) under mild conditions 2 , 15 .…”

Section: Introductionmentioning

confidence: 99%

Electrocatalytic upcycling of polyethylene terephthalate to commodity chemicals and H2 fuel

et al. 2021

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Plastic wastes represent a largely untapped resource for manufacturing chemicals and fuels, particularly considering their environmental and biological threats. Here we report electrocatalytic upcycling of polyethylene terephthalate (PET) plastic to valuable commodity chemicals (potassium diformate and terephthalic acid) and H2 fuel. Preliminary techno-economic analysis suggests the profitability of this process when the ethylene glycol (EG) component of PET is selectively electrooxidized to formate (>80% selectivity) at high current density (>100 mA cm−2). A nickel-modified cobalt phosphide (CoNi0.25P) electrocatalyst is developed to achieve a current density of 500 mA cm−2 at 1.8 V in a membrane-electrode assembly reactor with >80% of Faradaic efficiency and selectivity to formate. Detailed characterizations reveal the in-situ evolution of CoNi0.25P catalyst into a low-crystalline metal oxy(hydroxide) as an active state during EG oxidation, which might be responsible for its advantageous performances. This work demonstrates a sustainable way to implement waste PET upcycling to value-added products.

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Section: Introductionmentioning

confidence: 99%

Electrocatalytic upcycling of polyethylene terephthalate to commodity chemicals and H2 fuel

et al. 2021

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“…A second option is delamination of MFPF by selective decomposition of polymer layers. [25] For example, Kulkarni et al studied the recovery of Al from multilayer packaging structures by depolymerizing PET and PA via the use of sub and supercritical water. [26] Also sulfuric acid was proposed at different concentrations to degrade PET from a MFPF consisting of PET and PE layers.…”

Section: Introductionmentioning

confidence: 99%

Towards a Better Understanding of Delamination of Multilayer Flexible Packaging Films by Carboxylic Acids

et al. 2021

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Recycling multilayer plastic packaging is challenging due to its intrinsic compositional heterogeneity. A promising route to increase recycling rates for these materials is delamination, which allows recycling the polymers separately. Yet, this process is not well understood on a fundamental level. This study aimed to obtain first principles-based insights of the delamination mechanism of multilayer flexible packaging film (MFPF) with carboxylic acids. Delamination of MFPFs was described through a model based on Fick's first law of diffusion and first-order dissolution kinetics of polyurethane adhesives. The model was experimentally tested on 5 different MFPFs at different temperatures (50-75°C), formic acid concentrations (50-100 vol %), and solid/liquid (S/L) ratios (0.005, 0.025, and 0.12 g mL À 1 ). Under the studied conditions the model proved to successfully estimate the delamination time of MFPF with the average Theil's Inequality Coefficient (TIC) value of 0.14. Essential for scaling-up delamination processes is the possibility to use high S/L ratios as the solubility of the adhesive is rarely limiting.

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“…Furthermore, the increased thickness of the samples and the presence of multilayers reduce the decomposition yield by a factor of two, as observed for monolayer (80%) versus multilayer PET trays (45%). Using the optimized alkaline hydrolysis with further cleaning processes, the different types of colors, including carbon black, were removed from the hydrolysate successfully [ 186 ]. Mancini and Zanin reported that the PET hydrolysis occurred preferentially at the chain ends and superficially, having as controller mechanism the acid diffusion into the polymer structure [ 187 ].…”

Section: Factor For Recycling Petmentioning

confidence: 99%

Strategic Possibility Routes of Recycled PET

2021

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The polyethylene terephthalate (PET) application has many challenges and potential due to its sustainability. The conventional PET degradation was developed for several technologies to get higher yield products of ethylene glycol, bis(2-hydroxyethyl terephthalate) and terephthalic acid. The chemical recycling of PET is reviewed, such as pyrolysis, hydrolysis, methanolysis, glycolysis, ionic-liquid, phase-transfer catalysis and combination of glycolysis–hydrolysis, glycolysis–methanolysis and methanolysis–hydrolysis. Furthermore, the reaction kinetics and reaction conditions were investigated both theoretically and experimentally. The recycling of PET is to solve environmental problems and find another source of raw material for petrochemical products and energy.

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Towards closed-loop recycling of multilayer and coloured PET plastic waste by alkaline hydrolysis

Abstract: A two-step aqueous alkaline hydrolysis was carried out on different types of real PET plastic waste under mild conditions.

Cited by 297 publications

References 49 publications

Electrocatalytic upcycling of polyethylene terephthalate to commodity chemicals and H2 fuel

Electrocatalytic upcycling of polyethylene terephthalate to commodity chemicals and H2 fuel

Towards a Better Understanding of Delamination of Multilayer Flexible Packaging Films by Carboxylic Acids

Strategic Possibility Routes of Recycled PET

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