Superparamagnetic ZnFe2O4/ZnS nanocomposites with a highly recyclable for degradation of bisphenol A under visible-light

Superparamagnetic ZnFe2O4/ZnS core–shell sub-microspheres were fabricated via a two-step forming method for recyclable photocatalytic degradation of bisphenol A (BPA) driven by visible light. The ZnFe2O4/ZnS nanocomposites display much higher photocatalytic efficiency as compared to that of the individual ZnFe2O4, which could remove about 97.7% of BPA in 135 min. The enhancement of photocatalytic activity is mainly attributed to the synergy effect of the energy band gap between ZnFe2O4 and ZnS, resulting in the enhanced visible light absorbance and separation efficiency of photo-generated electron–hole pairs. Specifically, the ZnFe2O4/ZnS nanocomposites can retain their stable photocatalytic activity toward BPA photodegradation for six successive cycles of reaction with rate constants of 0.0281–0.0272 min−1 under visible light irradiation. The highly recyclable and stable performance of ZnFe2O4/ZnS nanocomposites might benefit from its superparamagnetic, which nanocomposite could be rapidly separated from aqueous solution by an external magnetic field, and without agglomeration when magnetic field removed. Our work demonstrates a practical means for fabrication of superparamagnetic nanocomposite to improve the visible light photocatalytic activity and reusability of photocatalyst.