Functionalized geopolymer foams for cesium removal from liquid nuclear waste

• Published in: Journal of cleaner production Vol. 269; p. 122400
• Main Authors: Petlitckaia, S., Barré, Y., Piallat, T., Grauby, O., Ferry, D., Poulesquen, A.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2020; Elsevier
• Subjects: Cesium uptake; Chemical Sciences; Competitive ions; Functionalized geopolymer foam; Ion exchange; Material chemistry; Selectivity; Cesium uptake; Selectivity; Ion exchange; Functionalized geopolymer foam; Competitive ions
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2020.122400

Geopolymer foam hosting a 3D network of interconnected pores was synthetized and functionalized with a potassium copper hexacyanoferrate [K2CuFe(CN)6] in order to decontaminate radioactive liquid waste containing cesium. The Geopolymer Foam (GF) and Functionalized Geopolymer Foams (FGF) were characterized using a panel of characterization techniques (SEM, TEM, XRD …) before studying their capacity to remove selectively cesium from the solution. K2CuFe(CN)6 homogeneously precipitates on the pore walls of the foam and into the mesoporous network. Exploiting kinetic and adsorption isotherms in various solutions (deionized water, fresh water and fresh water with excess of sodium), a comparative study between the GF and FGF was undertaken. In presence of competitive ions into the solution, the capacity of both materials decreases with respect to the deionized water. The mechanism of exchange is Na+ ↔ Cs+ and K+ ↔ Cs+ for GF and FGF respectively. Although the GF material presents some very high performances in term of ion exchange, in excess of sodium ions, the GF material completely loses its capacity with respect to the FGF that remains constant up to 1 mol/l−1. FGF is therefore very selective with regard to the cesium if other cations coexist into the solution. This is also confirmed by experiments performed in radioactive environment for very low concentration of radioactive cesium where the distribution coefficient (Kd) for the FGF reaches in average 3.5 105 ml g−1 that is ten times higher than for the GF material. [Display omitted] •Geopolymer foam with an interconnected pore network functionalized by [K2CuFe(CN)6].•FGF decontaminates selectively traces of Cs even in presence of coexisting ions.•GF completely loses its Cs uptake capacity in presence of sodium excess (seawater).•One gram of FGF is able to efficiently treat 350 L of Cs contaminated effluent.