Electrodialysis (ED) Cell for Water Treatment and Mineral Extraction, CWTMEEDC

Electrodialysis (ED) and Electrodeionization (EDI) are electromembrane separation processes driven by an applied DC electric field to transport dissolved ions through ion-exchange membranes (IEMs), separating an electrolyte solution into dilute and concentrated streams.

An electrodialysis cell consists of repeating cell pairs compressed between an anode and a cathode: (1) Membrane Repeating Unit: Alternating Cation Exchange Membranes (CEM) (fixed negative charges, permeable to cations) and Anion Exchange Membranes (AEM) (fixed positive charges, permeable to anions). (2) Flow Compartments: Dilute Compartment: Ions migrate out across the membranes under the electric potential gradient. Concentrate Compartment: Ions entering from adjacent diluate channels are trapped by opposing selective membranes, building up solute concentration. (3) Electrode Rinse Compartment: Circulates an electrolyte solution (e.g., Na2SO4) across inert electrodes (Ti/IrO₂ or Pt-coated anodes; stainless steel or Ti cathodes) to manage redox reactions (O2/H2 evolution) and prevent precipitation. (4) Electrodeionization (EDI) Specifics: In EDI, the diluate channels are packed with mixed-bed ion-exchange resin beads. The resin acts as an ionic conductor at low salinities, allowing continuous deionization down to high resistivity (>18 MΩ*cm) while applied voltage splits water (H+ and OH-) to regenerate the resin in situ without chemical reagents.

References:

1. S. Abu Khalla, et al., Desalination via chemical energy: An electrodialysis cell driven by spontaneous electrode reactions, Desalination, 2019, 467, 418-427. 

2. M. Amores, et al. Electrodialysis as a Method for LiOH Production: Cell Configurations and Ion-Exchange Membranes, Adv. Sustain. Mater., 2025, 9, 2400402