Copper hexacyanoferrate cathode as a selective adsorbent for ammonium ions in sodium-rich solutions

Abstract Ammonium ion remediation has led to innovative methods, such as Faradaic redox reaction using Prussian blue. Our approach uses an adsorption reaction that is controlled by electric current instead of potential. By sweeping the potential through current control, selective adsorption of NH4+ was achieved in solutions with high concentrations of Na+ (ca. 1:50). The use of thick electrodes enabled ammonium levels to be reduced to environmentally acceptable levels in 3 steps, even from highly concentrated solutions of NH4+ (200 mmol/L).