Sorption of cesium, strontium, and yttrium radionuclides from the aqueous phase on layered double hydroxides

Abstract

Sorption of 137Cs, 85,90Sr, and 90Y from aqueous solutions on the solid phase of layered double hydroxides (LDHs) and layered double oxides (LDOs) of various compositions was studied. On the solid phase of Mg-Al and Cu-Al LDHs and Mg-Al LDO, the Sr and Cs radionuclides are very weakly sorbed from aqueous solutions containing 10−5 M of the corresponding element (Cs+ or Sr2+). Introduction of EDTA ions into Mg-Al LDH increases the distribution coefficients K d of Sr by a factor of more than 40. After 96-h contact of the solid and liquid phases, K d of radioactive Sr in sorption from aqueous solution on Mg-Al LDH and Mg-Al LDH-EDTA is 2.4 and 100 ml g−1, respectively. The Sr and Y radionuclides are efficiently sorbed from aqueous solutions containing 10−5 M Sr2+ and Y3+ on the Mg-Nd LDH solid phase. After 5-min contact of the solid and liquid phases, K d of Sr exceeds 105 ml g−1. For Y, the distribution coefficients equal to 700–800 ml g−1 are attained after 30-min contact of the solid and liquid phases. Aging of the Mg-Nd LDH precipitate does not affect its sorption properties toward Sr and Y radionuclides. With an increase in the Sr(NO3)2 concentration in the solution from 10−5 to 10−1 M, the distribution coefficients K dz of Sr drastically decrease (virtually to zero) and those of Y change insignificantly.