Chemo‐enzymatic depolymerization of industrial and assorted post‐consumer poly(ethylene terephthalate) (PET) wastes using a eutectic‐based catalyst

Abstract

BACKGROUND: Every minute, 1 million bottled drinks were purchased worldwide in 2017. Poly(ethylene terephthalate) (PET) bottles are highly recalcitrant wastes, taking at least 450 years to decompose naturally, and their accumulation in the environment triggers a series of environmental impacts. Recycling is an environmentally friendly alternative to PET waste management. A two-step PET depolymerization approach was studied in this work, comprising chemical glycolysis followed by enzymatic hydrolysis.RESULTS: In the glycolysis reaction, 100% PET was depolymerized in the presence of a eutectic solvent-based catalyst and ethylene glycol, releasing bis(2-hydroxyethyl) terephthalate (BHET) as the main product (70% yield). The recovered BHET was then hydrolysed by the highly efficient Candida antarctica lipase B, releasing terephthalic acid (TPA), achieving 0.98 of mole fraction in the best result of the experimental design. The overall yield of chemo-enzymatic depolymerization of PET into TPA was 57%. CONCLUSION: Using this integrated approach, a high overall yield of TPA from PET could be achieved within a short process timeframe (24 h).

The Road to Sustainable Tire Materials: Current State-of-the-Art and Future Prospectives

“…61 One million bottled drinks are purchased worldwide (2017 report) every single minute, and about 583.3 billion units PET production were estimated in 2021. 62 Traditionally, methanolysis, glycolysis, ammonolysis, aminolysis, and hydrolysis constitute the most common PET chemical recycling methods. Reaction conditions are critical to maximize the monomer yield.…”

“…66 Further, chemo-enzymatic two-step depolymerization involving glycolysis followed by enzymatic hydrolysis is getting popular, with a monomer yield of up to 60%. 62 Glycolysis uses a glycol degrading agent such as ethylene glycol and candida Antarctica, or lipase B enzymes are usually employed for enzymatic recycling. 67 What challenges the enzymatic depolymerization of PET is the low catalytic turnover, kinetic instability, inhibition by other components during depolymerization, and a slower reaction rate due to early inactivation of enzymes.…”

“…It is critical that we look at various methods of regenerated PET manufacture as it is reported as a pivotal plastic pollutant in the marine waters . One million bottled drinks are purchased worldwide (2017 report) every single minute, and about 583.3 billion units PET production were estimated in 2021 . Traditionally, methanolysis, glycolysis, ammonolysis, aminolysis, and hydrolysis constitute the most common PET chemical recycling methods.…”

“…The early days challenge of an environmentally friendly way to recycle PET is being met in recent years by the enzymatic depolymerization of PET . Further, chemo-enzymatic two-step depolymerization involving glycolysis followed by enzymatic hydrolysis is getting popular, with a monomer yield of up to 60% . Glycolysis uses a glycol degrading agent such as ethylene glycol and candida Antarctica, or lipase B enzymes are usually employed for enzymatic recycling .…”

A general electrochemical strategy for upcycling polyester plastics into added-value chemicals by a CuCo2O4catalyst

“…They are widely used in packaging and textiles, and have formed a multi-billion dollar market. [4][5][6] Moreover, most polyesters are fossil-based polymers and their production will consume ∼20% of global oil supplies by 2050. 7 Their large-scale production and use, coupled with inadequate and unregulated end-of-life management, not only cause serious harm to the ecological environment and human health, but also enormous losses of valuable resources.…”