Persulfate enhanced photocatalytic degradation of bisphenol A over wasted batteries-derived ZnFe2O4 under visible light

Zinc ferrite (ZnFe2O4) with visible (Vis) light response was synthesized via sol-gel method by using waste alkaline Zn–Mn batteries as raw materials. The morphology, composition and optical properties of ZnFe2O4 were characterized. In order to suppress the fast recombination of photoinduced electron-hole pairs and improve the photocatalytic performance of ZnFe2O4, peroxydisulfate (PDS) was introduced to the photocatalytic system as the external electron acceptor. With the presence of PDS, the removal efficiency of target contaminant bisphenol A (BPA) achieved 96.5% in a 120 min reaction at natural pH 6.0. Photoluminescence (PL) spectroscopy combined with amperometric tests was used to determine the role of PDS on the performance of photocatalytic reaction. The main reactive species for BPA removal were determined by electron paramagnetic resonance (EPR) measurement and quenching experiments. The results indicated that the holes and reactive species (SO4•– and •OH) produced by activation of PDS with photogenerated electrons mainly contributed to the elimination of BPA. Furthermore, the effect of various operating parameters on the removal of BPA as well as the reusability and stability of catalyst was investigated to explore the applicability of ZnFe2O4 used in the PDS-mediated photocatalytic system for wastewater treatment. [Display omitted] •ZnFe2O4 with great visible-light response was prepared from waste batteries.•BPA could be oxidized by more than 90% in 90 min in Vis/ZnFe2O4/PDS system.•PDS effectively inhibited the recombination of photogenerated charge carriers.•Photogenerated holes together with SO4•– and •OH contributed to the removal of BPA.•The catalysts can be reused for at least 5 times with stable performance.