Cesium immobilization from aqueous solution by struvite synthesis

Abstract

To demonstrate the validity of the Cs decontamination process by synthesizing Cs-struvite (CsMgPO4·6 H2O) from a waste solution containing multiple cations, synthesis tests and tests confirming structural stability were performed. The synthesis test was conducted in a solution containing Na, K, Cs, Mg, and P. After 0.5 h stirring, Cs, Mg, and P were recovered, and the sample structure was confirmed as Cs-struvite. With the TG-DTA analysis, the absence of Cs vaporization was confirmed up to 1200°C. The gamma irradiation resistance of Cs-struvite was confirmed. Gamma irradiation using the Co-60 as the radiation source with a maximum radiation dose of 300 kGy caused no loss of Cs or structural changes. The elution test, in which samples were left to stand in distilled water for 7 days, showed that Cs-struvite had a higher water resistance than CsMgPO4, indicating that it is desirable to compress Cs-struvite directly after synthesis to obtain a solidified body with higher water resistance. The results demonstrated the feasibility of Cs removal by Cs-struvite synthesis and the stability of Cs-struvite.