Studies on copper(II) leaching from e-waste with hydrogen sulfate ionic liquids: Effect of hydrogen peroxide
Szymon Wstawski, Magdalena Emmons-Burzyńska, Martyna Rzelewska-Piekut, Andrzej Skrzypczak, Magdalena Regel‐Rosocka
Abstract
As the recovery, conversion and reuse of metals is a crucial concept of waste-to-resources (WTR) within a circular economy, the study was undertaken to check the effectiveness of using a new leaching system, containing hydrogen sulfate ionic liquids (with dimethyloctylammonium (IL1), 1-octylimidazolium (IL2) or 2-methyl−1-octylimidazolium (IL3) cations) to dissolve Cu(II) from e-waste, i.e. printed circuit boards (PCBs). Metal (Cu(II), Ag(I), Au(III)) leaching was attempted with 0.5 M IL solutions with or without the addition of H2O2 (an oxidant) for 3 h at 23 or 75 °C and at the solid to liquid ratio (S/L) of 1/20 g/cm3. No Au(III) and very small amounts of Ag(I) were determined in the leach liquor (leachate). Therefore the discussion and ANOVA analysis of the leaching results were performed only for Cu(II). It is shown that the ILs can be used as the leaching media but need the presence of an oxidant to leach high amounts of Cu(II) from e-waste. For example, the presence of IL1 was found to improve the leaching efficiency of the oxidant (H2O2) when compared to the leaching at pH ~ 1 without IL. These experimental results were confirmed by the ANOVA analysis, showing that the presence of H2O2 is the main statistically significant factor responsible for the efficient Cu(II) leaching in this system.