Removal of Cs(+) from water and soil by ammonium-pillared montmorillonite/Fe3O4 composite.

To remove cesium ions from water and soil, a novel adsorbent was synthesized by following a one-step co-precipitation method and using non-toxic raw materials. By combining ammonium-pillared montmorillonite (MMT) and magnetic nanoparticles (Fe3O4), an MMT/Fe3O4 composite was prepared and characterized. The adsorbent exhibited high selectivity of Cs(+) and could be rapidly separated from the mixed solution under an external magnetic field. Above all, the adsorbent had high removal efficiency in cesium-contaminated samples (water and soil) and also showed good recycling performance, indicating that the MMT/Fe3O4 composite could be widely applied to the remediation of cesium-contaminated environments. It was observed that the pH, solid/liquid ratio and initial concentration affected adsorption capacity. In the presence of coexisting ions, the adsorption capacity decreased in the order of Ca(2+)>Mg(2+)>K(+)>Na(+), which is consistent with our theoretical prediction. The adsorption behavior of this new adsorbent could be expressed by the pseudo-second-order model and Freundlich isotherm. In addition, the adsorption mechanism of Cs(+) was NH4(+) ion exchange and surface hydroxyl group coordination, with the former being more predominant.