• Gerold, Eva
• Antrekowitsch, Helmut
• Luidold, Stefan

Abstract

When processing residues and raw materials, it is important to ensure a high recovery rate in order to use them in by-products or to deposit as few valuable materials as possible. The removal of these substances from the material cycle should be avoided. This becomes evident in all leaching processes, especially regarding the efficiency of the operations, which can specifically be improved, for example, by dosing additives. At the recycling of lithium-ion batteries and hard metals, hydrogen peroxide serves frequently for that purpose, among other chemicals. Nevertheless, the self-decomposition of H2O2 proves to be a corresponding challenge in various wet chemical processes. This includes an<br/>exothermic disproportionation reaction which generates water and oxygen as products. Since these are non-toxic substances, the application of this chemical as an additive tend to be more environmentally friendly compared to operations that work for instance with ammonium peroxodisulfate. The decomposition can be intensified by various catalysts, with dissolved metal ions in particular exhibit a correspondingly high influence. From the electrochemical point of view, depending on its reactants, hydrogen peroxide can act both as an oxidizing and as a reducing agent. In the field of hydrometallurgical recycling of lithium ion batteries, not only inorganic acids have been applied recently, but organic acids found also usage as leaching solution, as these can have a positive effect on the selectivity of the process. The use of reduction agents accelerates the leaching operation itself and increases the metal yields in the filtrate. In recyclingprocesses, the decomposition of H2O2 plays a decisive role, since the efficiency of reconditioning procedures can decrease significantly as the peroxide content is reduced. The present work examined the decomposition behaviour ofhydrogen peroxide in oxalic acid (C2H2O4), ascorbic acid (C6H8O6), citric acid (C6H8O7) and formic acid (CH2O2) is under the presence of defined ions. A special focus lies on the determination of the influence of Co, Cu, Ni and Li ions. It is in economic and ecological interests to minimize the loss of H2O2 through selfdecomposition in water and oxygen. It turns out that the type of acid as well as of the metal ion have a significant influence on the process.

Topics

• impedance spectroscopy
• Oxygen
• Hydrogen
• leaching
• Lithium
• decomposition