Layer-Structured POSS-Modified Fe-Aminoclay/Carboxymethyl Cellulose Composite as a Superior Adsorbent for the Removal of Radioactive Cesium and Cationic Dyes

In this work, multifunctional Fe-aminoclay (FeAC)/carboxymethyl cellulose (CMC)/ polyhedral oligomeric silsesquioxane (POSS) composite (FeAC/CMC/POSS) with layered structure was successfully synthesized and utilized as adsorbent for the removal of cesium ions (Cs⁺) and cationic dyes methylene blue (MB) and chrysoidine G (CG) from aqueous solutions. The FeAC/CMC/POSS exhibit excellent adsorption capacities for Cs⁺ ions, MB and CG of 152, 438, and 791 mg g^-1, respectively. The adsorption capacities for Cs⁺ ions, MB and CG are substantially greater than those of many previously reported adsorbents due to (i) the layered morphology of the composite and abundance of amino (-NH₂) groups on clay surface and (ii) existence of carboxylate (-COO^-) and hydroxyl (-OH^-) groups on the CMC backbone, which contribute to the adsorption of large number of Cs⁺ ions and dye molecules through electrostatic attraction and ion-exchange process. More importantly, the incorporation of POSS increases the interlayer spacing of Fe-aminoclay by intercalation providing room for the encapsulation of Cs⁺ ions and dye molecules. Owing to its unprecedented adsorption capacity, the devised FeAC/CMC/POSS composite could be a promising organic-inorganic material used to cost-effectively remove the multitude of environmental pollutants.