Bis(2-pyridylmethyl)amine-Modified Chitosan Beads for Efficient Separation of Ni(II)/Co(II) in Acidic Solutions

The pursuit of high-purity cobalt is driven by its irreplaceable role in advanced electronic devices, particularly as a promising interconnect material for next-generation integrated circuits. However, the coexistence of nickel, which shares highly similar physicochemical properties with cobalt, presents a critical bottleneck in achieving electronic-grade purity cobalt. Developing efficient and selective separation materials is therefore paramount. In this study, we designed and synthesized an environmentally friendly adsorbent-chitosan beads functionalized with bis(2-pyridylmethyl)amine (CBs-PY). The CBs-PY adsorbent exhibits exceptional selectivity for Ni(II) over Co(II) under strongly acidic conditions (pH 2), achieving a remarkable separation factor of 100.31, significantly outperforming conventional pyridine-based resins. X-ray absorption spectroscopy (XANES/EXAFS) revealed the formation of stable Ni–N2 coordination structure on CBs-PY, with adsorbed Ni(II) ions showing low surface oligomerization. Furthermore, the adsorbent demonstrats excellent acid stability, reusability, and consistent performance in high-salinity environments. This work provides a sustainable and efficient strategy for the separation of Ni(II) and Co(II) in acidic media, offering significant potential for applications.