Development of a continuous electrolytic system with discharging only one pH-controlled stream and its characteristics

Abstract

In order to produce only a pH-controlled solution without discharging any unused solution, this work has developed a continuous electrolytic system with an ion exchange membrane-equipped electrolyzer and a tank, called as a pH-adjustment reservoir, placed just in front of the electrolyzer, where as a target solution was fed into the pH-adjustment reservoir, a portion of the solution in the pH-adjustment reservoir was circulated through the cathodic or anodic chamber of the electrolyzer depending on the type of the ion exchange membrane used, and another portion of the solution in the pH-adjustment reservoir was discharged from the electrolytic system through the opposite electrode chamber with its pH being controlled. The internal circulation of the pH-adjustment reservoir solution through the anodic chamber in the case of using a cation exchange membrane and that through the cathodic chamber in the case of using an anion exchange membrane could make the solution, discharged from the other counter chamber, effectively acidic and basic, respectively. The phenomena of the pH being controlled in the system could be explained by the electro-migration of the ion species in the solution through the ion exchange membrane under a cell potential difference between the anode and the cathode and its consequently-occurring non-charge equilibriums and the electrolytic water-split reactions in the anodic and cathodic chambers.