Digital Electrochemical Separation for Critical Raw Material Recovery: Metals and REEs

Objective

The selective recovery of Critical Raw Materials (CRMs) from dilute, multi-component aqueous solutions is fundamentally constrained by the limitations of conventional separation technologies, which lack simultaneous high selectivity and energy-efficient reversibility. This project, DIGISEP, aims to overcome this scientific barrier by developing a novel class of electro-active, stimuli-responsive membranes for programmable ion separation. The primary objectives are to engineer intrinsic chemical selectivity into a sustainable, conductive composite and to elucidate a new dual-mode separation mechanism. This mechanism synergistically combines voltage-gated physical transport (actuation) with electrochemically modulated chemical affinity. This will be achieved by fabricating a bicontinuous network of cellulose nanofibers, functionalized with covalently grafted chelating ligands, and the conductive polymer PEDOT:PSS and carbon nanotubes. The application of a low voltage potential will be used to induce localized electrochemical phenomena (pH swings or direct redox reactions) at the ligand sites. This will reversibly modulate the ligands' binding affinity, enabling a digitally controlled capture and release of target ions (e.g., REEs, Pb²⁺, AuCl₄⁻) without the use of bulk chemical regenerants. The relevance of this work to the programme is direct and substantial. By creating a breakthrough technology for valorizing secondary resources, DIGISEP provides a tangible scientific pathway to achieving the EU's strategic autonomy goals as defined in the Critical Raw Materials Act and advancing the Circular Economy Action Plan. This project pioneers a fundamental, low-energy separation platform to address a critical European technological and environmental challenge.