Researchers, including faculty members from the Oregon State University School of Engineering, have taken an important step toward significantly expanding the range of recyclable plastics.
The findings published today in Science are important because plastic waste is a major problem globally and in the United States.Five%According to the U.S. Department of Energy’s National Renewable Energy Laboratory, which led the study, 30% of used plastic is recycled.
According to NREL, packaging, containers and other waste fill landfills and enter the environment at such a rapid pace that scientists estimate that by 2050 there will be more plastic in the ocean than fish by weight. increase.
The collaboration, led by NREL’s Greg Beckham and including OSU researcher Lucas Ellis, who was a postdoctoral fellow at NREL during the project, combines chemical and biological processes to turn mixed plastic waste into ” We conducted a proof of concept to “value”. Valorize means to increase the value of something.
This research is based on the use of chemical oxidation to degrade various types of plastics. This method was developed by DuPont, a giant of the chemical industry, ten years before him.
“We have developed a technique that uses oxygen and catalysts to break down plastics into smaller, biofriendly chemical building blocks,” said Ellis, assistant professor of chemical engineering. “From there, we can use biologically engineered soil microbes to consume these building blocks and ‘infuse’ them into biopolymers or components of advanced nylon production. ”
Mr. Beckham, Senior Research Fellow at NREL and Head of Bio-Optimized Technologies, an environmental consortium known as BOTTLE, is responsible for bio-optimized technologies to keep thermoplastics out of landfills. The work “provides a potential entry point into the processing of plastics that cannot be recycled at all,” he said. today. “
Beckham explains that current recycling technology works only if the incoming plastic is clean and sorted.
Plastics can be made from a variety of polymers, each with its own chemical building blocks. When polymer chemicals are mixed in collection bins or formulated together in certain products, such as multi-layer packaging, it is often necessary to separate the polymers before recycling, making recycling costly and nearly impossible. It will be possible.
“Our work has resulted in a process that can convert mixed plastics into a single chemical product,” Ellis said. “In other words, this is a technology that recyclers can use without sorting plastics by type.”
The researchers applied this process to mixtures of three common plastics. His terephthalate polyethylene, which is the basis for carpets, polyester clothing and disposable beverage bottles. High density polyethylene used in milk jugs and many other consumer plastics.
The oxidation process breaks down the plastic into a mixture of compounds such as benzoic acid, terephthalic acid and dicarboxylic acids. In the absence of artificial soil microorganisms, sophisticated and costly separations are required to obtain a pure product.
The researchers engineered the microbe Pseudomonas putida to biologically infuse the mixture into one of the two products. polyhydroxyalkanoates, a new form of biodegradable bioplastic, and beta-ketoadipate, which can be used to make high-performance nylons.
Testing the process with other types of plastics, such as polypropylene and polyvinyl chloride, will be the focus of future research, the researchers said.
“The chemical catalytic process we used is just a way to accelerate a naturally occurring process, so instead of taking hundreds of years to degrade, we can degrade these plastics in hours or minutes,” he said. , says co-author and postdoc Kevin Sullivan, a NREL researcher.
Funding was provided by the US Department of Energy’s Office of Advanced Manufacturing and the Office of Bioenergy Technologies, and work was performed as part of the BOTTLE consortium.
Scientists from the Massachusetts Institute of Technology, the University of Wisconsin-Madison, and Oak Ridge National Laboratory also participated in the study.
NREL is the U.S. Department of Energy’s primary national laboratory for research and development in renewable energy and energy efficiency. It is operated for the sector by Alliance for Sustainable Energy, LLC.