upcycling plastic bags

CHRISTINE SUH: Plastic bag pollution has become a huge environmental problem, prompting some cities and countries to heavily tax or ban the sacks. But what if used plastic bags could be made into higher value products? Now, researchers have reported a new method to convert plastic bags into carbon chips that could be used as anodes for lithium ion batteries. They report their results in ACS Omega.

Many plastic bags are used only once and then disposed, ending up in landfills, oceans, and elsewhere in the environment where they can take hundreds of years to decompose. The polyethylene in plastic bags could be a cheap source of energy-storing carbon, but current methods to upcycle the plastic are too expensive and complex.

Vilas Pol and colleagues wanted to develop a simpler, yet efficient, approach to convert plastic waste into useful carbon-containing materials. In their new method, the researchers immersed polyethylene plastic bags in sulfuric acid, sealed them inside a reactor, and heated the sample to just below polyethylene's melting temperature. This caused sulfonic acid groups to be added to the polyethylene carbon-carbon backbone.

Then they removed the sulfonated polyethylene from the reactor and heated it in a furnace at 1,600 degrees Fahrenheit to produce pure carbon. The team ground the carbon into a black powder and used it to make anodes for lithium ion batteries. The resulting batteries performed comparably to commercial batteries and could be used to power this toy truck.