One of the most alarming aspects of the increasingly
negative impact of humans on our overburdened Earth is the weight of
indestructible plastic in our landfills and, worse, in our oceans. Only about
20-30 percent of even the most recyclable of our plastic waste can be refashioned
into usable form. The rest must go to the landfill (where it remains forever or
leaches out into the environment) or be incinerated.
We’ve seen the horrible results of plastics
that find their way to our oceans: floating garbage islands many meters across
drifting with the currents; whales and other sea creatures dying with their bellies
full of micro-bits of plastic that contaminate the plankton and krill the
creatures use as food.
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| Lost in a sea of plastic garbage. |
In the U.S., where plastics based on petrochemicals are
ubiquitous, calling for reducing use of the material is a hard sell.
Individuals can cut back on their own use of plastic at home, but the problem
is bigger than that. Even municipal recycling programs are having a difficult
time finding a market for their plastic now that China has stopped accepting
it.
Technology, though, may provide part of the
answer. According to a post in Science
Daily News, scientists at the
U.S. Department of Energy's (DOE) Lawrence Berkeley National Laboratory have developed
a new type of plastic that can be recycled by taking it apart at the molecular
level, and putting it back together again in any shape, texture, and color. The
process can be repeated again and again without loss of performance or quality.
Discovery of the new material, called poly(diketoenamine), or PDK, was reported
in the journal Nature Chemistry.
The PDK process
strips plastic polymers down to their constituent monomers by dunking the
material in an acid bath. This also allows for the removal of any additives
that might have given the old material its color, flexibility, toughness or
other special characteristics. The new material is like a basic building block that
can be recombined in all sorts of new ways. PDK can be torn down and built back
up multiple times, making it reusable in a circular process, not just a one-time
linear process as is true of conventional plastics.
Peter
Christensen, a postdoctoral researcher at Berkeley Lab's Molecular Foundry, was
lead author of the study that announced the discovery. He admits, “Most plastics
were never made to be recycled.” But that was before the team he was part of
looked at recycling from “a molecular prospective.”
Christensen’s multidisciplinary
team was led by Brett Helms, a staff scientist in Berkeley Lab's Molecular
Foundry. The DOE/Lawrence Berkeley National Laboratory reports the other
co-authors were undergraduate researchers Angelique Scheuermann (then of UC
Berkeley) and Kathryn Loeffler (then of the University of Texas at Austin) who
were funded by DOE's Science Undergraduate Laboratory Internship (SULI) program
at the time of the study. The overall project was funded through Berkeley Lab's
Laboratory Directed Research and Development program.
Team leader Brett
Helms is clear about the potential impact of the discovery of PDK on our
environmental future. "We're at a critical point where we need to think
about the infrastructure needed to modernize recycling facilities for future
waste sorting and processing," said Helms. "If these facilities were
designed to recycle or upcycle PDK and related plastics, then we would be able
to more effectively divert plastic from landfills and the oceans. This is an
exciting time to start thinking about how to design both materials and
recycling facilities to enable circular plastics."
Cheers, Donna
*Information
for this post taken from: “Plastic gets
a do-over: Breakthrough discovery recycles plastic from the inside out,” Science
Daily News, DOE/Lawrence Berkeley National Laboratory, May 7, 2019. https://www.sciencedaily.com/releases/2019/05/190507110452.htm
