One-pot synthesis of hierarchical magnetite nanochain assemblies with complex building units and their application for water treatment

We report that unique hierarchical magnetite (Fe3O4) nanochain assemblies with complex flower-like nanostructures as secondary building blocks and smaller nanoparticles as primary building blocks can be prepared by a facile and surfactant-free one-pot approach using Fe(acac)(3) as precursor in polyol solution. The resultant Fe3O4 nanochains possess superparamagnetic property, large saturation magnetization (82.1 emu/g), high Brunauer-Emmett-Teller (BET) specific surface area (43.5 m(2) g(-1)), and also good water-dispersibility. Thanks to these wonderful intrinsic properties, the Fe3O4 nanochains exhibit excellent ability to remove an organic pollutant in waste water. For example, Congo red, a common azo-dye in textile industry, can be completely removed within 5 min at room temperature when the initial concentration of Congo red in solution was 100 mg/L. In addition, the Fe3O4 assembled tertiary chain-like structures can be recycled by a simple heat treatment, which keeps almost the same removal ability and a litter slower adsorption rate even used for the third time. Beyond as an adsorbent for water treatment, these Fe3O4 nanochain assemblies may be useful in other fields such as magnetic resonance imaging (MRI), and drug delivery based on their novel structures and intrinsic multi-functionalities.