Page 45 - Plastics News March 2021

teChnoLogy

Studies indicate constant amounts A mild way to upcycle plastics

of litter in coastal marine systems used in bottles

in recent years
hen plastic-containing items have fulfilled their
Wmissions, only a small amount is recycled into new
re plastics and microplastics in the Ocean on the products, which are often of lower quality compared
Aincrease? The answer might not be so straightforward. to the original material. And, transforming this waste
And perhaps that is the question that Prof. Alan Deidun, into high-value chemicals requires substantial energy.
resident academic within the Department of Geosciences Now, researchers have combined a ruthenium-carbon
of the Faculty of Science, along with a cohort of high- catalyst and mild, lower-energy reaction conditions to
convert plastics used in bottles and other packaging into
fuels and chemical feedstock. The researchers Yuriy
Román-Leshkov and colleagues developed a method to
react simple hydrocarbon chains with hydrogen in the
presence of noble- or transition-metal nanoparticles
under mild conditions. In their experiments, ruthenium-
carbon nanoparticles converted over 90% of the
hydrocarbons into shorter compounds at 392 F. Then,
the team tested the new method on more complex
polyolefins, including a commercially available plastic
bottle. Despite not pretreating the samples, as is
necessary with current energy-intensive methods,
profile co-authors, posed within a study recently published they were completely broken down into gaseous and
in the Microplastics and Nanoplastics journal. Specifically, liquid products using this new method. In contrast
the study overviews a plethora of marine litter monitoring to current degradation methods, the reaction could
survey data available for different regions of the world be tuned so that it yielded either natural gas or a
ocean, as well as modelling data, in order to answer this combination of natural gas and liquid alkanes.. Global
compelling question. The study, whose lead author is litter production of sturdy, single-use plastic for toys, sterile
researcher Dr Francois Galgani from IFREMER, concludes medical packaging, and food and beverage containers
that, despite the well-known increase in the volume of is increasing. Polyolefin polymers, such as polyethylene
plastics making their way to the marine domain from and polypropylene, are the most common plastics used
land, most studies indicate constant amounts of litter in these products Yuriy Román-Leshkov and colleagues
in coastal marine systems in recent years until 2019.
For instance, collections of marine litter by Continuous
Plankton Recorders showed relatively unchanged amounts
trapped annually in the North East Atlantic since the year
2000, following a steady increase since the 1950s. For some
components of marine litter, such as industrial pellets,
policy-making seems to be effective given that measures
taken to reduce their use in industrial practices seem to
have translated into smaller volumes of this component
being detected within the marine domain. Although a prima wanted to see if metal-based catalysts would have
facie a surprising find, this 'steady state' scenario could be a effect on solid polyolefins with long hydrocarbon
indicative of: a transfer of plastic litter to remote areas of chains, disintegrating them into usable chemicals and
the global ocean, where human monitoring programmes natural gas.The researchers say implementing their
are non-existent or subdued, such that the same litter method could help reduce the volume of post-consumer
does not feature in statistics and/or, the degradation into waste in landfills by recycling plastics to desirable,
smaller fragments (micro- and nanoplastics) of the same highly valuable alkanes, though technology is needed
litter which can go undetected due to its small size. to make the process economically feasible.

45 March 2021 Plastics News