Bipolar Membrane Electrodialysis (ED) Cell for Water Treatment and Mineral Extraction, CWTMEBMEDC

A Bipolar Membrane Electrodialysis (BPED) cell is an advanced electrochemical separation technology that combines traditional electrodialysis with the unique catalytic water-splitting property of bipolar membranes (BPMs). Unlike standard ED systems that only transport ions between streams, BPED actively converts salts into their corresponding acids and bases in situ without requiring external chemical reagents (like NaOH or HCl).

A standard BPED stack is typically configured in a three-compartment repeating unit bounded by an anion-exchange membrane (AEM), a cation-exchange membrane (CEM), and a bipolar membrane (BPM): (1) Bipolar Membrane (BPM): Composed of an anion-exchange layer (facing the anode) and a cation-exchange layer (facing the cathode) with a catalytic interface. Under a reverse-biased electric field, water molecules at the junction undergo accelerated dissociation. (2) Acid Generation: Protons (H+) migrate through the cation-exchange side of the BPM into the adjacent acid compartment, combining with incoming anions (e.g., Cl- or SO4^{2-}) to form high-purity acids. (3) Base Generation: Hydroxide ions (OH-) migrate through the anion-exchange side of the BPM into the adjacent base compartment, combining with incoming cations (e.g., Na+ or Li+) to form hydroxides. (4) Salt (Dilurate) Depletion: The central salt stream is progressively depleted of ions as they migrate toward their respective product loops.

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