Enhance antimony adsorption from aquatic environment by microwave-assisted prepared Fe₃O₄ nanospherolites

A novel hierarchically nanostructured magnetite (Fe₃O₄) was manufactured using microwave-assisted reflux method without surfactants. The nanostructured Fe₃O₄ is formed via the co-precipitation of Fe(III) and Fe(II), followed by a nanocrystal aggregation-based mechanism. Moreover, the effects of solution pH, contact time, initial Sb concentration, coexisting anions, and recycle numbers on the adsorption of nanostructured Fe₃O₄ toward Sb were extensively examined in the batch adsorption tests. The results demonstrated that the obtained Fe₃O₄ exhibited excellent adsorption ability toward Sb with the maximum adsorption capacities of 154.2 and 161.1 mg.g^-1 for Sb(III) and Sb(V), respectively. The prepared Fe₃O₄ could be easily regenerated and reused for adsorption/desorption studies multiple times without compromising the Sb adsorption ability. Further exploration indicated that the oxidation or reduction reactions infrequently occurred during Sb adsorption processes. The proposed hierarchically nanostructured Fe₃O₄ thus could be potentially used for sustainable and efficient antimony removal.