Electrodialysis Pump Based on Enhanced Water Dissociation of Bipolar Membrane

We describe a novel micropump mode–electrodialysis pump (EDP), which is based on the recombination of hydrogen and hydroxyl ions generated by enhanced water dissociation of bipolar membrane (BPM). The pump is in a sandwich-like configuration in which the central production channel is spatially isolated from two outer regenerant chambers by a BPM, respectively. Both BPMs are put at the same direction, in which the anion exchange membrane (AEM) side is facing the anode with respect to the cation exchange membrane (CEM) side facing the cathode. Pure water as the feed solution flows through the regenerant chambers at a conventional flow rate (e.g., 0.2 mL/min). Under the electric field, enhanced water dissociation at the junction layer of BPM will occur, generating hydroxyl and hydrogen ions. Their electrodialytic migration into the central channel will recombine water and its flow rate is correlated with the applied current. The pump shows near-ideal Faradaic efficiency and at least 0.8 μL/min can be achieved by controlling the current. The produced water is near neutral and obvious enrichment of trace impurity anions is observed in the production channel.