Retracted Article: Magnetic Fe3O4@NiO hierarchical structures: preparation and their excellent As(v) and Cr(vi) removal capabilities

Abstract

Uniform three-dimensional (3D) flowerlike Fe₃O₄@NiO hierarchical architectures were synthesized by a simple and direct solvothermal route without any linker shell. The shell thickness and hierarchical structure of the microspheres can be tuned by adjusting the reaction duration. The size of the hierarchical microspheres is 250–300 nm and the shell is composed of several nanoflakes with a thickness of 20–30 nm and a width of 50–60 nm. The microspheres possess high specific surface area of 125.63 m² g⁻¹ and high saturation magnetization, which allows them to have strong removal ability and are easily separated from solution by magnetic separation method. The microspheres are applied as adsorbents for As(V) and Cr(VI) ions removal from wastewater, and exhibit a high adsorption capacity with an adsorption capacity of ∼117.6 mg g⁻¹ for As(V) and 184.2 mg g⁻¹ for Cr(VI), which is mainly attributed to the large specific surface area and hierarchical structures of Fe₃O₄@NiO hierarchical microspheres. This work provides a promising approach for the design and synthesis of multifunctional microspheres, which can be used for water treatment, as well as having other potential applications in a variety of biomedical fields including drug delivery and biosensors.