Self-assembled magnetite peony structures with petal-like nanoslices: one-step synthesis, excellent magnetic and water treatment properties

Abstract

Self-assembled magnetite (Fe₃O₄) peony structures with petal-like nanoslices have been successfully synthesized by a low-temperature and environmentally friendly one-step aqueous method without any surfactant and calcination treatment. Powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Mössbauer spectroscopy and superconducting quantum interference device magnetometer measurements were used to characterize the samples. The experimental results indicate that the use of the organic additive triethanolamine (N(CH₂CH₂OH)₃) has an obvious impact on the morphologies of the products. The possible formation mechanism for the Fe₃O₄ peony structures with well-defined morphology has been presented in detail. The magnetic and electrical properties of the Fe₃O₄ peony structures are investigated. The sample shows a ferrimagnetic behaviour with a high saturation magnetization of 88.4 emu g⁻¹ at 295 K. Low-field magnetoresistance of ca. −2.0% is achieved in an applied magnetic field of ±1.0 T at 295 K. In addition, the as-prepared Fe₃O₄ peony materials are studied as adsorbents in waste-water treatment, and exhibit an excellent ability to remove Cr(VI) pollutant from aqueous solution. The Fe₃O₄ peony sample demonstrates ca. 5.24 mg g⁻¹ of adsorption capacity towards Cr(VI) ions favourably comparing with commercial and reported adsorbents.