Researchers at the Illinois Sustainability Technology Center (ISTC) of the Prairie Research Institute of the University of Illinois (UI) have developed the first energy-efficient and environmentally friendly process that separates mixed polymers so that they can be recycled into new, high-quality plastic products.
The process uses a solvent called NMP. Different from DCM in use today that releases carcinogenic vapors into the air at near-room-temperature conditions, NMP will only release vapors when heated to 180 Celsius degrees Celsius, far above the temperature needed to dissolve the polymers.
A particularly efficient feature of the new process is the ability to condense the evaporated solvent for reuse again and again.
The savings don't end there. The process leaves behind some residual polymer waste. And the researchers can convert those remnants into usable fuel oil by a thermochemical process called pyrolysis.
The researchers have successfully demonstrated this new solvent process with small quantities at the lab scale, and it has produced polymers with comparable quality to their virgin-material counterparts.
"The next steps will be to run the recycled polymers through a manufacturing process and test for quality," said ISTC researcher and study co-author B.K. Sharma. "If successful, we can then begin a pilot-scale project."
E-waste from refrigerators, televisions, computers, monitors, mobile phones and video game consoles is an ever-increasing burden to landfills and the recycling industry. While parts of these materials are readily recyclable, the remaining plastics are a challenge because of their complex mixed-polymer composition.
The findings have for the first time demonstrated a nontoxic, nondestructive and energy-efficient chemical solvent process to recover polymers from more complex plastic blends, and have been published in the journal ACS Sustainable Chemistry & Engineering.