Synthesis of magnetically recyclable Fe3O4@NiO nanostructures for styrene epoxidation and adsorption application

A solvothermal method combining a calcination process was conducted to synthesize Fe3O4@NiO core-shell hierarchical nanostructures. First, Fe3O4 microspheres were synthesized through a solvothermal method by using ethylene glycol as solvent. Second, Fe3O4@Ni(OH)(2) core-shell hierarchical nanostructures were prepared through an in situ growing procedure. Third, Fe3O4@NiO core-shell hierarchical nanostructures were obtained from the Fe3O4@Ni(OH)(2) precursors by a simple calcination procedure. The results showed that the Fe3O4 core was about 250 nm in diameter and the NiO shell was around 30 nm in thickness. The Fe3O4@NiO core shell nanostructures were used as a magnetically separable adsorbent for the removal of Congo red (CR) dye from aueous solution, which exhibited a high adsorption capacity of 128.9 mg g(-1). Moreover, the Fe3O4@NiO core-shell nanostructures displayed a superior catalytic property for the epoxidation of styrene with an extremely high selectivity (100%), conversion (99%) and yield (99%). Such Fe3O4@NiO catalyst could be conveniently recycled from the reaction system by using a magnet and without any noticeable catalytic deactivation even after five cycles. The results indicate that the as-prepared core-shell materials can be used as a recyclable catalyst for the epoxidation of styrene. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.