Treatment of Water Contaminated with Radiocesium Using Novel Complexes between Prussian-Blue and Bivalent Transition Metal Hydroxides

Stabilization of Prussian blue using copper sulfate for eliminating radioactive cesium from a high pH solution and seawater

Prussian blue (PB), an adsorbent for the selective elimination of radioactive cesium from water, is highly versatile due to its unique crystal structure. However, PB crystals quickly decompose in an alkaline solution, generating hazardous cyanide contamination. In this research, the alkaline susceptibility of PB was remedied by incorporating copper sulfate as a protector. A stability assessment was conducted at several environmental conditions, such as high pH and temperatures from 10 °C to 50 °C, in seawater, artificial seawater, and river water. The crystalline and chemical stability of PB in the new class of composite was extremely high, even at a pH value of 11.2, as confirmed using XRD and total cyanide analysis. A comprehensive mechanism study revealed that, at high pH, the copper ions that cover the PB react with hydroxide ions to form copper hydroxide and shielding inner crystals. To decontaminate radioactive cesium, the first step was to immobilize nano PB on a cellulose nanofiber, followed by copper sulfate stabilization. Then, a spongiform adsorbent was made using polyurethane as the precursor. The new stabilized PB showed promising adsorption efficiency. Thus, this research will open a new range of applications for all existing and emerging PB-based adsorbents.

Magnetic graphene oxide based nano-composites for removal of radionuclides and metals from contaminated solutions

Magnetic graphene oxide based composites of the nano-particle size of <10 nm were synthesized, characterized and used in sorption experiments. The adsorption of Cs(I), Co(II), Ni(II), Cu(II) and Pb(II) to nano-composites was studied in a wide range of initial concentrations and analyzed by Langmuir and Freundlich models. In addition, the effects of pH and coexisting ions on the adsorption of Cs to Prussian blue based composites were investigated. The maximum adsorption capacities of studied elements varied from 29 to 641 mg g^-1. The obtained Langmuir and Freundlich constants indicated the dominating physisorption mechanism and favorable adsorption conditions.