The double-strike approach uses chemical catalysts to break down mixed plastic waste, allowing bacteria to transform what’s left over into desirable compounds.
technology
October 13, 2022
Mixtures of plastics are difficult to break down as most recycling methods only work for one type. Ninewat Kenyota/Shutterstock
A combination of chemical catalysts and engineered bacteria has been used to transform common plastic waste mixtures into useful products. I can.
The process of converting plastic waste into useful chemicals tends to focus on a single plastic, making it difficult to design facilities that can handle the mixture of plastic waste required for a truly circular economy. is.
Greg Beckham and his colleagues at Colorado’s National Renewable Energy Laboratory designed a two-step process that uses readily available catalysts and modified soil bacteria. Pseudomonas putida, Handles most common plastic waste mixtures.
This group combines polystyrene, polyethylene terephthalate (PET), and high-density polyethylene (HDPE) with biodegradable compounds called polyhydroxyalkanoates, which are frequently used in biomedical applications such as suturing and tendon repair. Successfully converted to family.
The first step in the process borrows from common industrial methods for producing terephthalic acid, one of the building blocks of PET. It uses oxygen and a chemical catalyst to break down the carbon bonds in mixed plastic waste, making the resulting compounds more digestible for bacteria.
“Step 1 is like a big hammer. You just use oxygen and a simple chemical catalyst to make an oxygenated, bioavailable intermediate. Then you manipulate the organism to We pour them into one product,” says Beckham.
Beckham and his team engineered bacteria in this study to produce polyhydroxyalkanoates, but instead other more widely used ones, such as easily recyclable and environmentally friendly plastic building blocks. Getting bacteria to produce products is viable. They also want to expand this method to address a wider variety of plastics.
“The beauty of synthetic biology, metabolic engineering, and this biological funneling idea is that as long as organisms can eat or consume oxygenated intermediates, they can potentially make anything. says Beckham.
The concept of combining chemical degradation and biological transformation is novel and could form part of a new recycling chain for mixed plastic waste, says Mike Shaver of the University of Manchester, UK.
“The idea that these polymers can be pretreated with catalysts to get diverse feedstocks that can be put together to make them more economically viable is very important,” he says.
However, the process has only been demonstrated in the lab so far and needs to be shown to make economic sense in the real world, he adds.
Journal reference: chemistryDOI: 10.1126/science.abo4626
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