Sensitive Detection of Metal Concentrations in Aqueous Solution Using Real-Time Micro-Plasma Emission Spectroscopy

The global demand for green energy stimulates the need for rechargeable batteries and their components, containing lithium, cobalt, manganese, copper, and nickel. Consequently, the quantitative determination of the battery metals has crucial importance in optimizing associated processes and waste management. The fundamental properties of an analyzer for continuous process and field measurements are sensitivity, selectivity, stability, mobility, and robustness. Unfortunately, these characteristics are lacking in numerous existing methods for metals monitoring. Hence, this gap led us to demonstrate the performance of micro-discharge optical emission spectroscopy (µDOES), a novel online trace metal analyzer. This study shows that the new online analyzer with its simple and compact design can match requirements for real-time determination of metals in aqueous solutions in the field. The performance of the system is defined with copper, nickel, and lithium dissolved in deionized water. The limit of detection (LOD) along with long-term repeatability for Cu, Ni, and Li in continuous analysis reached 0.9, 4.1, and 0.1 µg/L, and 2, 2, and 4.2%, respectively. The applicability of the technique to a real-world application is demonstrated by analyzing a hydrometallurgical black mass sample received from the recycling process of lithium-ion batteries.