Simultaneous removal of radioactive cesium and strontium from seawater using a highly efficient Prussian blue-embedded alginate aerogel

Abstract

Radioactive cesium (137Cs) and strontium (90Sr) contaminants in seawater have been a serious problem since the Fukushima accident in 2011 due to their long-term health risks. For the effective and simultaneous removal of radioactive cesium (137Cs) and strontium (90Sr) from seawater, a Prussian blue (PB)-immobilized alginate aerogel (PB–alginate aerogel) was fabricated and its adsorption performance was evaluated. PB nanoparticles were homogeneously dispersed in the three-dimensional porous alginate aerogel matrix, which enabled facile contact with seawater. The PB–alginate aerogel exhibited Cs+ and Sr2+ adsorption capacities of 19.88 and 20.10 mg/g, respectively, without substantial interference because Cs+ and Sr2+ adsorption occurred at different adsorption sites on the composite. The Cs+ and Sr2+ adsorption onto the PB–alginate aerogel was completed within 3 h due to the highly porous morphology of the aerogel. The Cs+ and Sr2+ adsorption behaviors on the PB–alginate aerogel were systematically investigated under various conditions. Compared with Cs+ adsorption, Sr2+ adsorption onto the PB–alginate aerogel was more strongly influenced by competing cations (Na+, Mg2+, Ca2+, and K+) in seawater. 137Cs and 90Sr removal tests in real seawater demonstrated the practical feasibility of the PB–alginate aerogel as an adsorbent.