Waste Ceramic Capacitors as Efficient and Recyclable Catalyst for the Reduction of Nitroarenes into Anilines in Water at Room Temperature

This study deals with the use of ceramic capacitors (commercial, CC, or extracted from waste printed circuit boards, WC) as pre-catalysts for the reduction of nitroarenes into anilines using NaBH4 as reducing agent. Capacitors are frequently found in electronic waste (e-waste), since they are key components of mother boards. E-waste contain potentially toxic and polluting substances, which pose a threat to human health and the environment1. On the other hand, if properly managed, they become valuable resources thanks to their high content of critical raw materials2. In this procedure, after grinding and calcination, the magnetic fractions of CC and WC (i.e. MCC and MWC, respectively) were tested as catalysts in the reduction of nitroarenes to their corresponding amines, carried out under environmentally friendly conditions, using water as the solvent at room temperature. MCC and MWC were active and selective due to the presence of CuO. In addition, their magnetic properties allowed an easy removal from the reaction medium by means of an external magnet, permitting easy recycling of the catalyst for subsequent runs.