Sustainable copper ion selection from simulated multi-metal battery leachates using calcium-activated polyphenylene oxide derivatives

초록

Recycling valuable metals from battery wastewater is essential for sustainable resource management and environmental protection. This study presents a copper (Cu2+)-selective polyphenylene oxide (PPO)-based polymer adsorbent, functionalized with carboxyl (–COOH) and amide (–CONH–) groups and activated with calcium ions (Ca2+), to achieve efficient Cu2+ separation via ion exchange. While nickel (Ni2+) and cobalt (Co2+) are more economically valuable, Cu2+ poses significant environmental risks and requires selective removal to facilitate downstream recovery of Ni2+ and Co2+. The adsorbent exhibited high adsorption capacity and rapid kinetics for Cu2+, Ni2+, Co2+, and manganese (Mn2+) in single-component systems, and showed exceptional selectivity for Cu2+ in multi-component systems. The adsorption mechanism—driven by metal-ligand affinity and ligand transfer dynamics—was elucidated through spectroscopic analysis and density functional theory (DFT) calculations. When applied in a packed-bed configuration, the system enabled selective Cu2+ capture and Ca2+ recovery (85 %), supporting adsorbent reusability and process sustainability. With Cu2+ selectivity coefficients ranging from 101 to 666, over 90 % high-purity Cu2+ was recovered from a Cu2+/Ni2+/Co2+/Mn2+ mixture in a single pass. This work presents a scalable, eco-friendly approach with strong potential for treating simulated battery wastewater and recovering critical metals, thereby contributing to circular economy practices in industrial applications.

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