Good news! Human ingenuity beats plastophobia anytime!
Note "from cloth waste and plastic waste mixtures"! Previously, the necessary separation of trash had been a significant issue.
"... Importantly the method is selective, meaning it could recycle the PET in mixtures of plastics and textiles. ...
Chemists have been investigating depolymerisation reactions that can turn the PET back into re-usable monomers, but most known methods require high industrial temperatures and corrosive acids or bases.
These researchers’ new method can be done at under 200°C (low by industrial standards), and uses just alcohol and a cheap iron-based catalyst.
These researchers’ new method can be done at under 200°C (low by industrial standards), and uses just alcohol and a cheap iron-based catalyst.
The researchers found that mixing PET with ethanol and ferric chloride (FeCl3) or iron(III) bromide (FeBr3) for a couple of days, at 160-180ºC, yielded an almost-pure mixture of the monomers used to make PET. ..."
"... The research team has now developed a method for acid- and base-free depolymerization of PET bottles using ethanol and either FeCl3 or FeBr3, yielding diethyl terephthalate (DET) and ethylene glycol (EG) with high selectivity (98-99%). Iron trichloride (FeCl3), which is inexpensive and widely available, demonstrated superior catalytic performance at 160-180 ºC, comparable to their previous results using titanium catalyst. Notably, this method enabled the exclusive and selective depolymerization of PET from textile waste, which comprises PET and a mixture of PET and cotton, yielding DET and EG while quantitatively recovering cotton waste. The catalyst also facilitated the selective depolymerization of PET from plastic waste, including polyethylene. ..."
From the abstract:
"Acid-, base-free depolymerization of poly(ethylene terephthalate) (PET) with ethanol catalyzed by FeCl3, FeBr3 (1.0–5.0 mol%) gave diethyl terephthalate (DET) and ethylene glycol (EG) exclusively (98–99%, 160–180 °C), and FeCl3 showed better catalytic performance in terms of activity. The FeCl3 catalyst enabled exclusive, selective depolymerization of PET from textile waste to afford DET (and recovered cotton waste), strongly suggesting the possibility of chemical recycling of cloth waste by the transesterification in this catalysis."
Exclusive chemical recycling of PET from cloth waste and plastic waste mixtures (original news release) "A novel solution to the plastic waste problem: simple, selective depolymerization of polyesters using alcohol and a soluble iron catalyst"
Depolymerization of PET with ethanol by homogeneous iron catalysts applied for exclusive chemical recycling of cloth waste (open access)
Scheme 3 Acid-, base-free catalytic transesterification (depolymerization) of PET with ethanol catalyzed by FeCl3, FeBr3.
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