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

Shoichi Manabe; Vipin Adavan Kiliyankil; Tsuguo Kumashiro; Shoichi Takiguchi; Bunshi Fugetsu; Ichiro Sakata

doi:10.1016/j.jhazmat.2019.121979

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

J Hazard Mater. 2020 Mar 15:386:121979. doi: 10.1016/j.jhazmat.2019.121979. Epub 2019 Dec 25.

Authors

Shoichi Manabe¹, Vipin Adavan Kiliyankil², Tsuguo Kumashiro³, Shoichi Takiguchi³, Bunshi Fugetsu⁴, Ichiro Sakata⁵

Affiliations

¹ School of Engineering, The University of Tokyo, 7-3-1 Bunkyo-Ku, Tokyo 113-8656, Japan; Nanosummit Co. Ltd., Kawaguchi City, Kamiaoki 3-12, Saitama, Japan. Electronic address: manabe@ipr-ctr.t.u-tokyo.ac.jp.
² School of Engineering, The University of Tokyo, 7-3-1 Bunkyo-Ku, Tokyo 113-8656, Japan. Electronic address: vipin@ipr-ctr.t.u-tokyo.ac.jp.
³ Nanosummit Co. Ltd., Kawaguchi City, Kamiaoki 3-12, Saitama, Japan.
⁴ Policy Alternatives Research Institute, The University of Tokyo, 7-3-1 Bunkyo-Ku, Tokyo 113-0033, Japan.
⁵ School of Engineering, The University of Tokyo, 7-3-1 Bunkyo-Ku, Tokyo 113-8656, Japan; Policy Alternatives Research Institute, The University of Tokyo, 7-3-1 Bunkyo-Ku, Tokyo 113-0033, Japan.

PMID: 31891821
DOI: 10.1016/j.jhazmat.2019.121979

Abstract

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.

Keywords: Cesium adsorption; Copper sulfate; Cyanide suppression; Prussian blue; Stabilizer.