Someday, left-over toner in discarded printer cartridges could have a second life as bridge or building components instead of as trash, wasting away in landfills and potentially harming the environment. One group reports in ACS Sustainable Chemistry & Engineering that they have devised a method to recycle the residual powder in "empty" cartridges into iron using temperatures that are compatible with existing industrial processes.

Electronic waste is a broad category that encompasses everything from computers and televisions to ink cartridges and refrigerators. According to the European Toner and Inkjet Remanufacturers Association, 500 million cartridges out of the estimated 1.1 billion sold each year end up in landfills around the world. These "empty" cartridges can contain up to 8 percent of unused residual powder by weight and could leach compounds into the soil and underground water sources. In an attempt to reuse this electronic waste, researchers have transformed this substance into oils, gases and even an ingredient in asphalt. Now, Vaibhav Gaikwad and colleagues wanted to develop a brand-new way to re-use residual toner.

The researchers put toner powder in a furnace, heating it to 1,550 °C. This process converted the inherent iron oxide to a product that was 98 percent pure iron using the polymer resins within the toner powder as a source of carbon. The researchers say that this method would be ideal for industrial applications because iron and steel are typically made at this temperature. In addition, heating the powder at such a high temperature prevents toxic side products from forming, providing an environmentally friendly way to recycle residual toner.