According to the European Toner and Inkjet Remanufacturers Association, approximately 500 million printer cartridges end up in landfills each year, worldwide. And those cartridges, although supposedly empty, can still contain up to 8 percent residual toner by weight. Not only is this wasteful, but the toner can also leach into the soil. Now, however, scientists have devised a method of recycling it into iron.

Led by Dr. Vaibhav Gaikwad of Australia's University of New South Wales, the researchers placed toner powder in a furnace, where it was heated to 1,550 °C (2,822 °F). This converted the material's inherent iron oxide into 98 percent pure iron, using polymer resins present within the powder as a source of carbon.

Iron and steel are already manufactured at such temperatures, so the process could be carried out in the same facilities, at the same time. Additionally, the high temperature reportedly prevents toxic side products from forming as the toner is recycled.

A paper on the research was recently published in the journal ACS Sustainable Chemistry & Engineering.