Attapulgite has been applied in the sorption of metal and radionuclide ions since its discovery. Herein, radionuclide Am(III)
sorption onto attapulgite was carried out at 25 °C in 0.01 mol/L NaNO3 solutions. Effects of contact time, Am(III) initial concentration, pH, humic acid and temperature on Am(III) sorption onto
attapulgite were investigated. The sorption of Am(III) increases with increasing contact time and reaches a maximum value
within 24 h at different Am(III) initial concentration. The fast sorption velocity indicates that strong chemical sorption
or strong surface complexation contributes to the sorption of Am(III) onto attapulgite under the experimental conditions.
The experimental data can be described well by the pseudo-second-order rate model. The sorption of Am(III) onto attapulgite
is strongly dependent on pH values and surface complexation is the main sorption mechanism. The presence of HA enhances the
sorption of Am(III) onto attapulgite at pH < 8.5, whereas, at pH > 8.5, little effect of HA on Am(III) sorption is observed.
The Langmuir, Freundlich and D-R models were used to simulate the sorption data at different pH values and the results indicated
that Langmuir model simulates the experimental data better than Freundlich and D-R models. The thermodynamic parameters indicates
that the sorption of Am(III) onto attapulgite is an endothermic and spontaneous process. The results suggest that the attapulgite
is a suitable material as an adsorbent for preconcentration and immobilization of Am(III) from aqueous solutions.