Researchers have come up with a novel way to produce plastic using carbon dioxide and inedible plant material, offering a low-carbon alternative to plastics made from petroleum.
But more than just replacing petroleum-derived plastic with one made from carbon dioxide, the researchers' goal was to develop a means that doesn't require a lot of non-renewable energy during production. By achieving this, the researchers have made it possible to dramatically lower the plastic industry's carbon footprint.
Plastics today are generally made from polyethylene terephthalate (PET), a polymer also known as polyester. About million tons of the material are made around the world every year for use in electronics, fabrics, personal care products and recyclable beverage containers.
Aside from containing a component derived from refined petroleum, PET also results in significant levels of carbon dioxide being released into the atmosphere. According to Matthew Kanan, one of the researchers, every ton of PET produced generates over four tons of carbon dioxide. As a greenhouse gas, carbon dioxide is a known contributor to global warming.
For the study published in the journal Nature, Kanan and colleagues turned to polyethylene furandicarboxylate (PEF), an alternative to PET made from 2-5-Furandicarboxylic acid (FDCA) and ethylene glycol.
However, while PEF has a number of desirable traits, it is not widely adopted because the plastics industry doesn't have a low-cost way to produce the material sustainably at scale.
There's a way to make PEF using FDCA derived from corn syrup but it is discouraged because growing crops requires a lot of resources and it competes with food production.
Fortunately, there's another way to make FDCA: by using inedible biomass, like grass or agricultural waste left over from harvests.
This option requires a compound made from agricultural waste called furfural. To negate the required hazardous chemicals for production, the researchers used a more benign compound called carbonate.
A molten salt was formed when carbonate is combined with furoic acid, a furfural derivative, and carbon dioxide. After just five hours, 89 percent of the molten salt has been converted to FDCA.
The resulting FDCA was then combined with ethylene glycol to produce PEF.
Aside from harnessing carbon dioxide, PEF is considered a sustainable product because it can be recycled. It can also be converted back into atmospheric carbon dioxide when incinerated, taken up once again by grass and other plants that can be used to make more PEF.
Photo: Gabriel Thomas | Flickr