Effect of Ionic Strength,Temperature and Humic Substances Concentration on the Sorption of ~(63)Ni(II) to γ-Al_2O_3

The sorption of 63Ni(Ⅱ) on γ-Al2O3 was studied by using batch technique.The effect of contact time,pH,ionic strength,γ-Al2O3 content and humic acid on the sorption of 63Ni(Ⅱ) on γ-Al2O3 was investigated under ambient conditions.The results suggest that the sorption of 63Ni(Ⅱ) is strongly dependent on ionic strength at low pH values,and independent on it at high pH values.The sorption of 63Ni(Ⅱ) at low pH is mainly dominated by ion exchange and/or outer-sphere surface complexation,whereas the sorption of 63Ni(Ⅱ) at high pH is mainly dominated by inner-sphere surface complexation.The presence of humic acid enhances 63Ni(Ⅱ) sorption to HA-γ-Al2O3 hybrids at low pH values,but reduces 63Ni(Ⅱ) sorption to HA-γ-Al2O3 hybrids at high pH values.