The mesoporous molecular sieves (Al-MCM-41) are synthesized with montmorillonite as silica–alumina source by hydrothermal
method. The application of Al-MCM-41 for the adsorption of Th(IV) from aqueous solution is studied by batch technique. The
effects of contact time, solid content, pH, ionic strength, foreign ions, and temperature are determined, and the results
indicate that the adsorption of Th(IV) to Al-MCM-41 is strongly dependent on pH values but independent of ionic strength.
The adsorption isotherms are simulated by D–R and Freundlich models well. The thermodynamic parameters (ΔH0, ΔS0, ΔG0) are calculated from the temperature dependent adsorption isotherms at 293, 313 and 333 K, respectively, and the results
suggest that the adsorption of Th(IV) on Al-MCM-41 is a spontaneous and endothermic process. Al-MCM-41 is a suitable material
for the preconcentration of Th(IV) from large volumes of aqueous solutions.