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

Sorption of 137 Cs, 85,90 Sr, and 90 Y 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 Sr 2+ ). 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 Sr 2+ and Y 3+ on the Mg-Nd LDH solid phase. After 5-min contact of the solid and liquid phases, K d of Sr exceeds 10 5 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(NO 3 ) 2 concentration in the solution from 10 −5 to 10 −1 M, the distribution coefficients K d z of Sr drastically decrease (virtually to zero) and those of Y change insignificantly.