Sorption of 60Co from aqueous solutions on layered double hydroxides of Mg, Al, and Nd

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Sorption of U(VI) from aqueous solutions of various compositions on layered double hydroxides (LDHs) of Mg, Al, and Nd, and also on layered double oxides (LDOs) of Mg and Al was studied. Experiments on sorption of UO22+ carbonate complexes from aqueous solution on LDO-Mg-Al showed that [UO2(CO3)3]4− ions are weakly captured by LDH-Mg-Al formed by contact of LDO-Mg-Al with water. With an increase in the uranium concentration in solution, Kd of U(VI) decreases. For 3.3 × 10−3 M [UO2(CO3)3]4− solutions, after 24-h contact of the solid and liquid phases, the distribution coefficients do not exceed 1.0 ml g−1 at V/m = 50 ml g−1. From aqueous nitrate solutions, U(VI) is sorbed on LDH-Mg-Al-NO3 poorly: Kd of U(VI) does not exceed 1.0 ml g−1 at 24-h contact of the solid and liquid phases and V/m = 50 ml g−1. At the same time, U(VI) is efficiently sorbed from aqueous 10−3 M UO2(NO3)2 solutions on LDH-Mg-Al and LDH-Mg-Nd with CO32− and OH− ions in the interlayer space. After 15-min contact of the solid and liquid phases, Kd of U(VI) exceeds 5 × 103 ml g−1. With an increase in the UO22+ concentration to 10−1 M, Kd of U(VI) decreases considerably, becoming lower than 25 ml g−1, but increases to ∼150 ml g−1 with an increase in the contact time of the solid and liquid phases to 24 h. The effect of the Na+, Ca2+, Cl−, and SO42− ions and of pH of the initial solution on the U(VI) sorption from aqueous UO2(NO3)2 solutions on LDH-Mg-Al-CO3 was examined.