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

Abstract

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 m² 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.