Page 56 - Plastics News April 2018

teChnoLogy

Researchers tap problematic e-waste surplus to recover high-quality

polymers

ixed-plastic electronics waste could be a valuable engineer and co-author Sriraam Chandrasekaran. "With
Msource of reusable polymers, a new study led candy, you dissolve sugar grains in water, allow the liquid
by Illinois Sustainability Technology Center scientists to become saturated with sugar, evaporate the water
suggests. The team has developed the first energy- and recover the polymer, which in this case is the candy.
efficient and environmentally friendly process that In our lab, we use plastic polymers instead of sugar and
separates mixed polymers so that they can be recycled the solvent we use is stronger than water." The most
into new, high-quality plastic products. E-waste from efficient solvent methods in use today involve a chemical
refrigerators, televisions, computers, monitors, mobile called DCM, which releases carcinogenic vapors into the
phones and video game consoles is an ever-increasing air at near-room-temperature conditions. These vapors
burden to landfills and the recycling industry. While contaminate the workspace and introduce the potential
parts of these materials are readily recyclable -- glass for release into the atmosphere, the researchers said.
and metals -- the remaining plastics are a challenge "Our process uses a solvent called NMP, which will only
because of their complex mixed-polymer composition. release vapors when heated to 180 degrees Celsius, far
"Items like water bottles and milk jugs can be recycled above the temperature needed to dissolve the polymers,"
easily because they are made from single polymers," said Chandrasekaran said.
ISTC researcher and study co-author B.K. Sharma. "Other
One particularly efficient feature of the new process is
plastic items, like cellphone cases, for example, are
the ability to condense the evaporated solvent for reuse
again and again. "The objective of studies like these is not
only to find ways to recycle this abundant mixed-plastic
waste, but to do so efficiently in an environmentally
benign way," Sharma said. The savings don't end there,
the researchers said. The process leaves behind some
residual polymer waste. However, the researchers
can convert those remnants into usable fuel oil by a
thermochemical process called pyrolysis, further diverting
these plastics from landfills."Ideally, we would like to
chop that step off and have the solvent process end in a
complete recycle," Chandrasekaran said. The team has
made of more complex polymer blends. They pile up at
successfully demonstrated this new solvent process with
recycling centers and eventually end up being incinerated
small quantities at the lab scale, and it has produced
or sent to landfills because there are no safe or efficient
polymers with comparable quality to their virgin-material
means of recycling them." The team's findings, published
counterparts. "The next steps will be to run the recycled
in the journal ACS Sustainable Chemistry & Engineering,
polymers through a manufacturing process and test for
are the first to demonstrate a nontoxic, nondestructive
quality," Sharma said. "If successful, we can then begin a
and energy-efficient chemical solvent process to recover
pilot-scale project." HOBI International, Inc. and the ISTC
polymers from these more complex plastic blends. "The
Hazardous Waste Research Fund supported this research.
process used to dissolve industrial polymers is not all that
The ISTC is part of the Prairie Research Institute at the
different than making hard candies," said ISTC research
University of Illinois.

Plastics News April 2018 56