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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 extal 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 Ca2+ ＞ Mg2+ ＞ 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.