Chemically bound Prussian blue in sodium alginate hydrogel for enhanced removal of Cs ions

A new approach for efficient removal of radioactive ¹³⁷Cs was developed using a sodium alginate hydrogel beads-based adsorbent containing chemically bound Prussian blue (PB). Sodium alginate was crosslinked with Fe (III) ions to form hydrogel beads, in which Fe (III) had a dual function; it served as a crosslinking agent and also led to PB formation via reaction with hexacyanoferrate. Fe (III) ions, an unusual crosslinking agent for sodium alginate gel, led to stable, homogeneous distribution of PB inside the beads. The amount of embedded PB in the composite beads was more than two times larger than in the conventional sodium alginate-PB composite beads, resulting in an adsorption capacity for Cs ions that was two to five times higher, mainly because of a higher PB contents and because of the microporosity of the sodium alginate hydrogel.