The EDI module consists of alternating layers of cation exchange membranes, anion exchange membranes, and ion exchange resins, forming a membrane stack structure with alternating desalination and concentrate chambers. Under DC voltage, cations and anions in the water migrate to their corresponding electrodes: cations permeate through the cation exchange membrane into the concentrate chamber but are blocked by the anion exchange membrane, while anions permeate through the anion exchange membrane but are blocked by the cation exchange membrane, thus achieving selective ion retention.
The mixed resin bed in the desalination chamber achieves dynamic purification through three synergistic effects: first, it adsorbs impurity ions from the water through ion exchange; then, driven by an electric field, the adsorbed ions migrate to the concentrate chamber; simultaneously, H⁺ and OH⁻ generated from water molecule electrolysis continuously regenerate the resin, maintaining its exchange capacity. This self-regeneration mechanism eliminates the need for system shutdown for chemical regeneration.