In the United States (US), researchers in the multi-discipline Bio-Optimized Technologies to keep Thermoplastics out of Landfills and the Environment (BOTTLE) Consortium have found that combining chemical and biological processes is a promising new strategy for the valorization of mixed plastic waste.
Different plastics are composed of different polymers, each with its own unique chemical building blocks.
When polymer chemistries are mixed—either in a collection bin or formulated together in materials such as multi-layer packaging—recycling becomes expensive and difficult because each polymer often must be separated prior to chemical deconstruction.
BOTTLE is a collaboration between scientists from the National Renewable Energy Laboratory (NREL) and peers from Oak Ridge National Laboratory (ORNL), the Massachusetts Institute of Technology (MIT), and the University of Wisconsin-Madison.
The BOTTLE team has developed a process that can convert mixed plastics to a single chemical product, working toward a solution that would allow recyclers to skip sorting plastic by type.
The process builds upon work pioneered a decade ago by a scientist from DuPont that used chemical oxidation to break down a variety of plastic types.
The NREL researchers expanded upon this chemistry, which uses oxygen and catalysts to break down large polymer molecules into smaller chemical building blocks.
The project also draws on synthetic biology expertise from ORNL researchers to engineer a microbe that converts deconstructed plastic waste into building blocks for next-generation materials.
By combing the two principles, the research team has developed two-stage oxidation and biological funneling approach that can break down and reform mixtures of common consumer plastics.
This plastic recycling research approach, which was funded in part by the US Department of Energy (DOE) Bioenergy Technologies Office (BETO) and Advanced Manufacturing Office, is discussed in a new paper “Mixed plastics waste valorization through tandem chemical oxidation and biological funneling” in the journal Science.
