Ammonium ion separation with an electrochemical ion exchange system (EIXS) using iron and copper hexacyanoferrate electrodes

초록

Ammonium ions in wastewater can induce toxicity in aquatic organisms and accelerate eutrophication. Therefore, the efficient removal of ammonium ions is necessary. The electrochemical ion separation method, based on an electrode with selectivity for ammonium ions, is a promising recovery technique that can efficiently adsorb and desorb ammonium ions. In this study, we propose an electrochemical ion exchange system (EIXS) that relies on copper hexacyanoferrate (CuHCF) and iron hexacyanoferrate (FeHCF) that is capable of recovering ammonium ions from source water containing various cations. This EIXS operates without expensive polymer electrolyte membranes, utilizing CuHCF electrodes to adsorb ammonium ions selectively while the FeHCF electrodes release sodium ions. The study analyzes the ion exchange behavior in solutions containing equal molar concentrations of sodium and ammonium ions, as well as simulated wastewater. Additionally, the cycling performance of the system was evaluated under various cationic conditions. The results demonstrate that EIXS effectively separates and recovers ammonium ions while maintaining lower energy consumption (6.9 Wh per mole of ammonium recovery from simulated wastewater) with high stability (capacity retention after 300 cycles: 96.8 %), making it a promising approach for practical applications. © 2025 Elsevier B.V.

키워드