Modeling and experimental study of low flow rate miniaturized electrodialysis for artificial kidney applications

In this study, the application of electrodialysis for ion recovery as an active transport mechanism is evaluated where a low flow rate of de-ionized water containing 100 mM NaCl concentration, close to that of total blood plasma concentration, enters an electrodialysis (ED) cell including two inert graphite electrodes to apply an electric field across an anion exchange membrane (AEM) and a cation exchange membrane (CEM) to separate the ions. A mathematical model of the cell is provided using extended Nernst–Planck equation, the resistance of the cell components are measured by a Luggin-capillary device, electrochemical impedance spectroscopy is used to study the ED cell behavior, and chronoamperometry is used to measure the clearance performance for various combinations of membranes. The results indicate that the electrodialysis cell with a single stack of AEM–CEM, effective area of 4 × 4 cm2, intermembrane spacing of 1 mm at a voltage of 4 V, and a volumetric flow rate of 30 ml/h can recover 40% of the ions with high current efficiency over 97%. A modular design using alternating AEM and CEM membranes in series and parallel will be able to process the desired volume of solution and achieve the required ion recovery rate. This study provides insights into the use of electrodialysis in the artificial kidney applications, where a miniaturized electrodialysis cell can reduce the device size significantly and allow for the emergence of long-awaited wearable devices to replace dialysis.