Chitosan nanoparticles (Ch NPs) with individual particles 10-30 nm in size and average aggregate sizes of 240 nm were prepared via ionic gelation. Ordered mesoporous Mobil Composition of Matter No. 41 (MCM-41) with a surface area of 1590 m 2 /g was prepared via a sol-gel method. The nanocomposites were prepared via the in situ dispersion of MCM-41 in chitosan followed by ionic gelation with a multivalent anion to produce MCM-41-impregnated Ch NPs or via the mixture of dispersed MCM-41 with preprepared Ch NPs to produce Ch NPs supported on MCM-41. The beryllium-uptake efficiency was studied with different pH values, contact times, and initial Be(II) concentrations. The maximum achieved uptake efficiencies of the nanocomposites (95% and 96%) were superior to that of MCM-41 (38%) and higher than that of Ch NPs (90%). The nanocomposite formulas facilitated post-treatment separation while maintaining a high beryllium-uptake efficiency. The Be(II)-uptake process for all of the materials followed the pseudo-second-order kinetic model and both the Langmuir and Freundlich isotherms.

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