Upcycling plastic waste into more valuable materials could make
recycling pay for itself

Date:
February 23, 2022
Source:
University of Bath
Summary:
Researchers have developed a new and simple method for upcycling
plastic waste at room temperature.



FULL STORY ==========================================================================
A new and simple method for upcycling plastic waste at room
temperature has been developed by a team of researchers at the Centre
for Sustainable and Circular Technologies (CSCT) at the University of
Bath. The researchers hope the new process will help recycling become
more economically viable.


========================================================================== Plastic waste residing in either landfill or the natural environment
currently outweighs all living biomass (4 Giga tonnes), culminating in
one of the great environmental challenges of the 21stcentury. Whilst
recycling rates are increasing across Europe, traditional methods remain limited because the harsh remelting conditions reduce the quality of
the material each time it's recycled.

Now researchers at the CSCT have developed a mild and rapid chemical
recycling process for polycarbonates, a robust class of plastics commonly
used in construction and engineering.

Using a zinc-based catalyst and methanol, they were able to completely
break down commercial poly(bisphenol A carbonate) (BPA-PC) beads within
20 minutes at room temperature.

The waste can then be converted into its chemical constituents, namely bisphenol A (BPA) and dimethyl carbonate (DMC), helping to preserve
product quality over an infinite number of cycles.

Importantly, BPA recovery prevents leakage of a potentially damaging environmental pollutant, whilst DMC is a valuable green solvent and
building block for other industrial chemicals.



========================================================================== Their results are published in ChemSusChem, noting enhanced process
efficiency and milder conditions compared to previous methods.

Promisingly, the catalyst is also tolerant to other commercial sources of
BPA- PC (e.g. CD) and mixed waste feeds, increasing industrial relevance, whilst being amenable to other plastics (e.g. poly(lactic acid) (PLA)
and poly (ethylene terephthalate) (PET)) at higher temperatures.

The team has also demonstrated a completely circular approach to producing several renewable poly(ester-amide)s (PEAs) based on terephthalamide
monomers derived from waste PET bottles. These materials have excellent
thermal properties and could potentially be used in biomedical
applications, for example drug delivery and tissue engineering.

Lead researcher Professor Matthew Jones, at the University of Bath's CSCT, said: "It's really exciting to see the versatility of our catalysts in producing a wide range of value-added products from plastic waste.

"It's crucial we target such products, where possible, to help promote
and accelerate the implementation of emerging sustainable technologies
through economic incentives." First author of the paper, Jack Payne
from the CSCT, said: "Whilst plastics will play a key role in achieving
a low-carbon future, current practices are unsustainable.



========================================================================== "Moving forward, it's imperative we source plastics from renewable
feedstocks, embed biodegradability/recyclability at the design phase
and diversify existing waste management strategies.

"Such future innovation should not be limited to emerging materials but encompass established products too.

"Our method creates new opportunities for polycarbonate recycling
under mild conditions, helping to promote a circular economy approach
and keep carbon in the loop indefinitely." Presently, the technology
has only been demonstrated on a small scale, however, the team is now
working on catalyst optimisation and scaling up the process (300 mL)
with collaborators at the University of Bath. The research was funded
by the Engineering and Physical Sciences Research Council.

========================================================================== Story Source: Materials provided by University_of_Bath. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Jack M. Payne, Muhammad Kamran, Matthew G. Davidson, Matthew
D. Jones.

Versatile Chemical Recycling Strategies: Value‐Added Chemicals
from Polyester and Polycarbonate Waste. ChemSusChem, 2022; DOI:
10.1002/ cssc.202200255 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220223111252.htm

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