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SIU researchers aim to turn drink waste into recyclable plastic

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Lahiru Javakody Plastics research

Lahiru Jayakody, foreground, assistant professor of microbiology at Southern Illinois University Carbondale, holds a petri dish in his laboratory recently. Jayakody is working with SIU researchers Ken Anderson and Matt McCarroll, back, left to right, on perfecting a process incorporating spent tea leaves and coffee grounds that would make single-use plastics biodegradable and more readily recyclable. The work also will involve student researchers, left to right, Lakshika Dissanayake and Sandipty Kayashta, graduate assistants, and Ryaan Ligon, a senior in chemistry.

Sometimes one solution leads to another.

Such is the case with a research projects at Southern Illinois University Carbondale – one that potentially could change how plastic products are used and reused.

Lahiru Jayakody, assistant professor of microbiology, is leading the project. He is working with veteran SIU researchers and senior investigators Ken Anderson and Matt McCarroll to perfect a process that would make everyday, single-use plastics biodegradable and more readily recyclable.

The process builds on another one, pioneered by Anderson. It also relies on spent tea leaves and coffee grounds to produce high-value chemicals that in turn can make biodegradable, efficiently recycled plastics. 

Plastics – specifically those made from polyethylene terephthalate (PET) are the most commonly produced around the globe. More than 26 million tons of PET annually goes into making carpet, clothing and single-use beverage bottles, among other products.

Plus, plastics make up more than 15% of the solid waste in U.S. landfills. While some plastic can be recycled, the process is inefficient.

“Plastic is everywhere,” Jayakody explained, “The current recycling process is not economically feasible. Mechanically, you can recycle only 30%.”

His experiences with plastic is considerable. Jayakody previously had found ways to use microbes to selectively deconstruct PET into its original chemical building blocks. He further used metabolically engineered microbes to convert those building blocks into high-value “platform chemicals,” or chemicals that serve as valuable precursors to other types of plastics or substances.

The new method relies on another patented process developed by Anderson called oxidative hydrothermal dissolution (OHD).

This process uses a “reactor” that initially combined coal, water, heat, pressure and oxygen, resulting in liquid chemical precursors for polymers and plastics. OHD, however, also can be used to turn other organic materials, such as plastic or plant biomass, into water-soluble, low-molecular-weight compounds.

Together, the two methods use waste from beverage production to make high-value chemicals. Those chemicals can be used to manufacture the biodegradable plastics that may be efficiently recycled.

The effort takes a waste product from Ito En, a Japanese beverage company – specifically, spent tea leaves and coffee grounds – using microbes to convert the material into a chemical which can be made to make new plastic.

“Our goal is to establish a green production platform with Ito En that will help protect our planet from single-use synthetic plastic by packaging its high-quality bottled green tea in novel eco-friendly biodegradable, recyclable plastic bottles,” Jayakody said. “Our technology adds value to the waste carbon in tea and coffee while creating high-value chemicals that provide a new revenue stream to the tea industry, while also helping the environment.”

Jayakody said there may be other uses for the process as well.

“We are trying to produce an alternative plastic to PET,” he said. “However, we can go in other routes to generate highly-advanced molecule polymers. For example, we can even produce a polymer for aerospace engineering or automotive manufacturing.”

But the three-year project is expected to result in a pilot plant and process single-use plastic.

“We are interested on generating new plastic that can be used as alternative to what is primarily being used now,” he said.

Friends, professors and fellow students of Jacob Jurinek gathered on SIU campus Monday night to honor his memory. He was among the eight victims who died Friday at the Astroworld Music Festival in Houston, Texas.

Tim Crosby of SIU Media Services contributed to this report. 



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