Recyclable Flower-like Fe₃O₄@SiO₂@NiO Nanoparticles for Rhodamine B Adsorption and Photocatalytic Degradation

Tremendous efforts have been dedicated to developing waste dye treatment methods that are recyclable and efficient. However, challenges such as high toxicity, poor dispersion in aqueous solutions, and the high residual rate problems of some catalysts persist. Herein, inspired by the superparamagnetic properties and the electrostatic absorption capacity of Fe 3 O 4 and the photocatalytic activity of NiO, flower-like, adsorptive-photocatalytic dual-effect dye scavengers, named Fe 3 O 4 @SiO 2 @NiO magnetic nanoparticles (FSN MNPs), are fabricated. The outermost NiO layer with a large specific surface area of 211.876 m 2 /g effectively adsorbs dyes via electrostatic interactions. More importantly, the introduction of an inert protective SiO 2 layer between the Fe 3 O 4 core and NiO shell enhances the chemical stability and catalytic performance of the FSN MNPs. These FSN MNPs are recyclable and can be reused at least six times. Their photocatalytic activity against rhodamine B (RhB) was assessed. They show a high RhB degradation efficiency of up to 99.50%. Therefore, the FSN MNPs are promising catalysts for dye degradation in industrial wastewater treatment applications.