Scientists master renewable, affordable, alternative plastic

10 Mar 2016

Step aside PET, we have a new, healthier, more Earth-friendly plastic in town. We even have a new acronym, with PEF the great white hope of the future.

That’s if you listen to Stanford University researchers, who have developed an affordable way to replace all the bad stuff in PET (polyethylene terephthalate), which makes up the vast majority of bottles and packaging you see today.

Rather than mess around with a ubiquitous plastic that produces four tonnes of CO2 for every tonne of PET produced, Matthew Kanan and his colleagues went down the biomass route for a solution.

PEF is greater than PET

Future Human

PEF is made from ethylene glycol and a compound called 2-5-Furandicarboxylic acid (FDCA). FDCA can be sourced from biomass, rather than petroleum, meaning, if produced on a large scale, it is far more desirable. “PEF is also superior to PET at sealing out oxygen, which is useful for bottling applications,” said Kanan.

PEF itself isn’t a new idea, but removing the production obstacles – such as finding a cost-efficient way to produce FDCA sustainably – could prove hugely significant. And it’s here that Kanan’s paper, published in Nature, comes into play.

Avantium is currently looking into producing FDCA from corn syrup conversion, however, as that requires land, energy, water and intense management, it’s hardly cheap, and hardly environmentally friendly.

Looking to make FDCA through “inedible biomass”, Kanan looked at grasses or waste material left over after harvest. More specifically, he looked at furfural, a compound made from agricultural waste. About 400,000 tonnes are produced annually for use in resins, solvents and other products.

Hazardous chemicals defeat the point

The issue they faced was hazardous chemicals are typically needed to complete this process. “That really defeats the purpose of what we’re trying to do,” Kanan said.

Kanan’s team of Stanford researchers instead used carbonate, combining it with Co2 and furoic acid, a derivative of furfural. Aanindeeta Banerjee, the lead author of the paper, then heated the mixture to about 200oC to form a molten salt.

The results were dramatic. After five hours, 89pc of the molten salt mixture had been converted to FDCA. The next step, transforming FDCA into PEF plastic, is, apparently, straightforward.

PEF PET bioplastic renewable plastic

Chemistry graduate student Aanindeeta Banerjee and assistant professor Matthew Kanan, via Mark Shwartz/Precourt Institute for Energy

What this all means is the Co2 needed to make PEF could be garnered from industrial sites or fossil fuel power plants already in production.

Products made of PEF can also be recycled or converted back to atmospheric C02 by incineration. Eventually, that Co2 will be taken up by grass, weeds and other plants, which can then be used to make more PEF.

Major global issue

The existence of plastic around the planet is a huge issue, with both its production and lifecycle causing significant stress on our natural environments.

A major study last year, for example, showed that 90pc of all seabirds have consumed plastic, with the likes of albatrosses and penguins now in trouble.

The DCU Water Institute is studying the dumping of phthalate chemicals, which are used to make plastic, and possible links with health problems. Elsewhere, a Dutch project wants to harvest all the plastic out in the oceans and turn it into Lego-like blocks to build roads.

But, if PEF can replace PET, then the production side of things could look far rosier.

“We believe that our chemistry can unlock the promise of PEF that has yet to be realised,” Kanan said. “This is just the first step. We need to do a lot of work to see if it’s viable at scale and to quantify the carbon footprint.”

Main image via Shutterstock

Gordon Hunt was a journalist with Silicon Republic