The uranium ion adsorption on the pristine MCM-41, amidoxime (AMD) and carboxyl (CA) groups modified particles was studied. The amounts of adsorbed U(VI) ions onto the pristine MCM-41, CA and AMD modified MCM-41 particles were found to be 58.9, 296.7 and 442.3 mg/g, respectively. The experimental equilibrium data was found to fit the Langmuir model well for all the tested adsorbents. The pristine, CA and AMD modified particles can be regenerated using 10 mM HNO3 solution with more than 95% recovery. Hence, AMD and CA modified particles are stable, and easily regenerated. Particularly, AMD modified MCM-41 particles with high adsorption capacity seems to be a promising adsorbent for removal of U(VI) ions from aqueous solutions. (C) 2015 Elsevier Inc. All rights reserved.