| Title |
Synergistic Leaching Behavior of Valuable Metals from NCM Black Mass in a Ternary Deep Eutectic Solvent System |
| Authors |
이지현(Ji Hyeon Lee) ; 김재형(Jea Hyung Kim) ; 문병화(Byeonghwa Moon) ; 홍현선(Hyun Seon Hong) |
| DOI |
https://doi.org/10.3365/KJMM.2026.64.9.799 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Complexation; Deep eutectic solvent; NCM black mass; Metal leaching; Reduction |
| Abstract |
In this study, the effects of the composition of choline chloride (ChCl)-based deep eutectic solvents (DESs) on the leaching behavior of transition metals from NCM (Ni-Co-Mn) black mass were systematically investigated. DESs with various compositions were prepared using ChCl as the hydrogen bond acceptor (HBA) along with citric acid (CA) and L-ascorbic acid (LAA) as hydrogen bond donors (HBDs), and the leaching efficiencies of Li, Ni, Co, and Mn were comprehensively compared. The ternary DES system exhibited superior leaching performance compared to its binary counterparts. Among the tested formulations, a ChCl:CA:LAA molar ratio of 2:0.5:0.5 yielded the highest total leaching efficiency of 79.5%. Optical analyses of the DESs and subsequent leachates revealed that the solution color and UV-Vis absorption behavior were strongly dependent on the coordination environment and distribution of dissolved metal species. The broad absorption observed in the range of approximately 350-450 nm was associated with changes in the coordination environment of Ni species, whereas the absorption in the 600-700 nm region was attributed to the optical contribution of Co-based coordination complexes. Despite similar Ni concentrations, variations in the UV-Vis absorption characteristics and solution color suggested that the optical properties of the leachates were governed not only by the concentration of metal ions but also by their coordination environment and speciation. Collectively, CA stabilizes dissolved metal ions through complex formation, whereas LAA facilitates metal dissolution via reductive reactions. These complementary functions indicate that the DES composition plays a critical role in controlling both the leaching efficiency and the solution characteristics. |