Direct Electrification of Liquid–Liquid Extraction by Imparting Fixed Charges onto Selective Redox Active Compounds

Electrochemically mediated liquid–liquid extraction (e-LLE) is a unique separation approach that relies on organic-soluble redox groups. The method combines continuous electrochemical operation with molecular selectivity for metal recovery. However, conventional e-LLE relies on multicolumn systems and indirect redox agents due to insufficient conductivity in apolar solvents. Here, we report a unique redox moiety integrating a ferrocene redox center with a permanently charged ammonium unit that imparts ionic conductivity even in organic solvents. This design enables the direct electrification of e-LLE using a single-column architecture. The redox extractant undergoes reversible electrochemical cycling without external electrolyte and selectively recovers anionic gold complexes from aqueous streams. Direct charging achieves up to 91% ferrocene oxidation, as quantified by Mössbauer spectroscopy, with close to 95% release of the bound ion upon reduction, thus outperforming chemical oxidation pathways. Implementation in a continuous flow cell simplifies the process and eliminates intermediate redox agents, enabling 89% gold uptake from electronic waste leachates with high selectivity. Fundamentally, this work establishes design principles for directly electrifying liquid–liquid separations while accelerating its industrial translation to mining and recycling.