Waste Plastics Become Functional Carbon Microspheres

Plastic grocery bags are handy and durable, but after the bread and milk are put away, most of the bags wind up in landfills. Argonne National Laboratory’s Vilas G. Pol has found a way to “upcycle” the discarded plastics into carbon microspheres, which could find new life in consumer products (Environ. Sci. Technol., DOI: 10.1021/es100243u). Pol heats waste plastics such as polyethylene bags and disposable polystyrene cups in a closed reactor. At 700 °C and about 1,000 psi, the hydrocarbons break down to hydrogen, hydrocarbon gases, and solid carbon powder, a process he monitored by mass spectrometry. Using electron microscopy, Pol found that the carbon powder is made up of 3- to 10-μm-diameter microspheres. The microspheres are paramagnetic and conductive, he notes, making them suitable for incorporation into printer toner, tires, paint, and lubricants, as well as in anode materials for rechargeable batteries. Pol is working with several companies interested in licensing the technology and developing the potential applications, he says.