Efficient electrochemical cesium recovery from seawater using nickel hexacyanoferrate-coated membrane-capacitive deionization cell for rapid analysis of 137Cs

Abstract

The increasing reliance on nuclear energy for carbon neutrality necessitates advanced technology for environmental radioactivity monitoring. Measuring radioactive cesium (137Cs) in the ocean takes over four days, underscoring the need for efficient analysis systems. In this study, we designed a membrane-capacitive deionization (MCDI) cell using nickel hexacyanoferrate (NiHCF), known for its high selectivity and electrochemical properties for Cs, as the electrode material. NiHCF powder was synthesized and characterized, confirming its significant Cs adsorption capabilities in seawater. The NiHCF electrodes were prepared using electrospraying and casting techniques, and their electrochemical properties were evaluated through cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical adsorption/desorption experiments with MCDI cells featuring electrosprayed NiHCF-coated electrodes demonstrated superior Cs adsorption and desorption efficiencies when using cast coatings; this was attributed to the porous structure of the electrosprayed coating, which facilitated better electrochemical reactions between NiHCF and the electrolyte. The most effective performance was achieved using a 47 μm-thick electrosprayed NiHCF film, demonstrating a desorption efficiency of approximately 91 % and adsorption and desorption capacities of 161 mg/g and 148 mg/g, respectively. This technology holds promise as a pretreatment method for analyzing 137Cs in actual seawater samples, thereby advancing environmental radioactivity monitoring. © 2024 Elsevier Ltd