Efficient Separation of Cadmium from Cobalt-Rich Solutions Using Cyanex301 and P204/P507

The presence of cadmium (Cd) in ternary batteries is a known detriment to both their service longevity and cycling performance. Traditional methods for reducing Cd levels in cobalt (Co) sulfate solutions can be effective but often result in significant losses of Co. This study introduces an enhanced dual-extractant system that combines 5% (V/V) di-2-ethylhexyl phosphoric acid (P204) with 5% (V/V) bis (2,4,4-trimethylpentyl) dithiophosphinic acid (Cyanex301) to effectively lower Cd content without substantial Co depletion. Conducted at a pH of 1.8 with a 1:1(V/V) organic-to-aqueous phase ratio at 25 °C for 10 min, our approach achieved a 99.99% extraction efficiency for Cd and limited Co extraction to just 0.53%. Subsequent stripping processes utilized 1 M sulfuric acid and 6 M hydrochloric acid to recover 87.13% of Co and 95.11% of Cd. An efficient process roadmap operated at optimized condition was demonstrated for plant-wide treatment of the cobalt sulfate solution containing Cd. The innovative results hold the potential to accelerate advancements in secondary resource recycling, especially Cd and Co.

Graphical Abstract