Thermal Transformation of Waste Toner Powder into a Value-Added Ferrous Resource

This paper describes the development of a thermal transformation process to recycle waste toner powder in a sustainable and environmentally friendly manner. The process leverages high-temperature reactions and the morphology and chemical composition of waste toner powder, mainly the iron oxide and carbon content, by utilizing the gases evolved during the thermal transformation as an in situ source of carbon to convert the waste toner powder into 98% pure iron. A temperature of 1550 °C was employed in the present study to ensure the complete transformation of waste toner powder to iron and also because of its practical relevance to operating conditions encountered in metal manufacturing and processing industries. The process delivers an iron recovery of 81.6%. X-ray diffraction, scanning electron microscopy–energy-dispersive spectroscopy, and inductively coupled plasma optical emission spectroscopy analyses were employed to confirm the composition of the metallic product. GC–MS analysis was utilized to monitor gaseous aromatic compounds during the thermal degradation studies of the waste toner powder, and none were detected above 1200 °C. In addition, this paper presents a comprehensive characterization of the waste toner powder and resultant products using various analytical techniques, a kinetic study of the thermal decomposition of waste toner powder, and a pelletization technique to overcome its material handling hazards.