Sorption study of radionickel on attapulgite as a function of pH, ionic strength and temperature

Sorption of radionickel on attapulgite is studied as a function of contact time, ionic strength, pH and temperature. The results indicate that the sorption of Ni(II) on attapulgite is strongly ionic strength-dependent at pH 8. Outer-sphere surface complexation or ion exchange contributes to Ni(II) sorption on attapulgite at pH 8. The sorption of Ni(II) on attapulgite increases with increasing temperature, and the thermodynamic parameters (ΔH 0, ΔG 0 and ΔS 0) calculated from the temperature dependent sorption isotherms suggest that the sorption of Ni(II) on attapulgite is a spontaneous and endothermic process. The high sorption capacity of attapulgite suggests that attapulgite is a suitable material for the preconcentration and solidification of radionickel from large volumes of aqueous solutions.