The Graduate was right. In the almost half century since Benjamin Braddock was counseled that plastics were the future, the world’s consumption of plastic—in bottles, bags, packaging, pipes, computer parts, and countless other applications—has skyrocketed. Around 300 million tons (270 million tonnes) of plastic are produced worldwide (paywall) every year. The US Environmental Protection Agency estimated that in 2012 alone, 32 million tons of plastic entered the US municipal solid waste stream, making up almost 13% of the total. Plastics usually are manufactured from petrochemicals like oil, and they leach dangerous substances as they break down in landfills or the ocean.
For all those reasons, researchers have long been looking for ways to produce similarly performing materials from renewable sources. The current bioplastic offerings generally are an improvement over their petroleum-based counterparts, but they’re expensive and energy-intensive to make and use crops like corn that could otherwise feed people.
Now a team of Italian researchers has developed a new method: turning the waste materials of industrial agriculture into renewable plastic.
It works when cocoa pod husks, rice hulls, or parsley and spinach stems are bathed in a solution of trifluoroacetic acid (TFA) to extract their cellulose, a strong biopolymer with a range of properties, from rigid to soft and stretchy. The resulting materials can be substituted for some conventional plastics, according to Ilker Bayer and his team at the Italian Institute of Technology, whose study appears this week in Macromolecules, published by the American Chemical Society. The process as the study’s authors describe it is faster and less expensive than standard methods for producing bioplastics. And as a bonus, it would put some of the world’s agricultural waste—as much as 24 million tons per year in Europe—to good use.