Redox-mediated electrochemical liquid–liquid extraction for selective metal recovery

Abstract

Electrochemical separations are powerful platforms for the sustainable recovery of critical elements, environmental remediation and downstream processing. However, the recent development of electroseparations has primarily focused on heterogeneous adsorbents, which face the challenge of intermittent electroswing operation. Here we present a redox-mediated electrochemical liquid–liquid extraction separation platform that translates selective single-site binding to a fully continuous separation scheme. A redox-active extractant is molecularly designed with controllable hydrophobicity to maximize organic phase retention. The redox flow design enables fully electrified continuous operation with no external chemical input, achieving the selective recovery of precious metals from multicomponent streams. We demonstrate an atomic efficiency of over 90% and over 100:1 selectivity for practical critical metal leach streams, and 16-fold up-concentration for gold and platinum group metals from varied feedstocks including electronic waste, catalytic converter waste and mining streams. Our work is envisioned as a pathway towards a broader class of industrially applicable liquid–liquid extraction-based electrochemical separations. The recovery of gold and platinum group metals from sources like electronic waste, catalytic converter waste and mining streams remains challenging. Now, an electrochemically mediated liquid–liquid extraction process leverages the selectivity of redox-active extractants for the selective recovery of precious and critical metals including gold and platinum group metals from diverse feedstocks.