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

Radioactive cesium (Cs) and strontium (Sr) 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 (Cs) and strontium (Sr) 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 Sr adsorption capacities of 19.88 and 20.10 mg/g, respectively, without substantial interference because Cs and Sr adsorption occurred at different adsorption sites on the composite. The Cs and Sr adsorption onto the PB-alginate aerogel was completed within 3 h due to the highly porous morphology of the aerogel. The Cs and Sr adsorption behaviors on the PB-alginate aerogel were systematically investigated under various conditions. Compared with Cs adsorption, Sr adsorption onto the PB-alginate aerogel was more strongly influenced by competing cations (Na, Mg, Ca, and K) in seawater. Cs and Sr removal tests in real seawater demonstrated the practical feasibility of the PB-alginate aerogel as an adsorbent.