Sorption of cesium on finely dispersed composite ferrocyanide sorbents

Author： Milyutin V. Kononenko O. Mikheev S. Gelis V.

ISSN： 1066-3622

Source： Radiochemistry, Vol.52, Iss.3, 2010-06, pp. : 281-283

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Abstract

Sorption of microamounts of cesium on finely dispersed composite ferrocyanide sorbents was studied. The sorbents were prepared by precipitation of nickel potassium ferrocyanide in the presence of various mineral supports (chalk, wollastonite, bentonite, clinoptilolite, diatomite, biosilica). The distribution coefficient (K _d) of ¹³⁷Cs on composite ferrocyanide sorbents is considerably higher than on nickel potassium ferrocyanide without support. The K _d values on the composite sorbents increase by a factor of 25–110 when separating the solid phase with a paper filter and by a factor of 4.3–8.2 when using a microfiltration membrane. Considerable increase in K _d of ¹³⁷Cs on composite sorbents is attributed to the formation of a nickel potassium ferrocyanide phase firmly fixed on the support surface and resistant to peptization. Composite ferrocyanide sorbents were tested for the ¹³⁷Cs recovery from a simulated NPP bottom residue in the pH range 8.5–12.0. On the composite sorbents, K _d of ¹³⁷Cs is 2.5–3.0 times higher than on the nickel ferrocyanide precipitate throughout the examined pH range. The composite sorbent based on biosilica and nickel potassium ferrocyanide was tested for treatment of real liquid radioactive waste with a total salt content of 22.0 g dm⁻³ to remove ¹³⁷Cs. The decontamination factor as high as 5190 was attained owing to simultaneous use of the finely dispersed composite ferrocyanide sorbent and an ultrafiltration ceramic membrane.