We tend to think all plastic is bad, but what if we were able to make a plastic from excess carbon?
A Stanford University study has worked out a way to do something along those lines -- forming plastic out of carbon dioxide (CO2) and plant material that cannot be eaten. The latter includes grasses and waste from agriculture. The idea is to offer a carbon-based alternative to current standard.
"Our goal is to replace petroleum-derived products with plastic made from CO2," Matthew Kanan at Stanford, said. "If you could do that without using a lot of non-renewable energy, you could dramatically lower the carbon footprint of the plastics industry."
Currently, many plastics are constructed from polyethlene terephthalate (PET), which is also polyester. About 50 million tons of this material are produced worldwide each year for electronics, fabrics, recyclable bottles and products for personal care.
PET has two main ingredients, ethylene glycol and terephthalic acid. Those are produced from natural gas and refined petroleum. The manufacturing process also "generates more than four tons of CO2 for every ton of PET that's produced," Kanan said.
Kanan and the team looked closely at an alternative to PET known as polyethelene furandicarboxylate (PEF). It is put together from ethylene glycol and the compound named 2-5-Furandicarboxylic acid (FDCA).
An existing approach to producing FDCA has been to make fructose from corn syrup, which uses land, fertilizer, and water -- and can compete for space with growing food, as Kanan noted.
So the Stanford researchers tried making FDCA using furfural, a material usually made from waste from agriculture. The latter has been used widely for dozens of years. However, using furfural and CO2 to construct FDCA tends to require dangerous chemicals as well.
Rather than follow that method, the research team decided to use carbonate, putting it together with CO2 and a derivative of furfural called furoic acid. Then graduate student Aanindeeta Banerjee, the study lead author, heated the combination to 290 degrees Fahrenheit.
Within about five hours, the majority of the mixture had become FDCA. After that, the team was able to speedily transform the FDCA into PEF plastic.
The study results were recently published in the journal Nature.
Follow Catherine Arnold on Twitter at @TreesWhales.
