Enhanced norfloxacin degradation by visible-light-driven Mn3O4/γ-MnOOH photocatalysis under weak magnetic field.

A valence-state heterojunction Mn3O4/γ-MnOOH was synthesized for norfloxacin (NOR) degradation under concurrent visible light and magnetic field. The charge carriers could transfer between the valence state components facilely, inhibiting recombination of photo-induced electron-holes significantly. Efficient NOR degradation by Mn3O4/γ-MnOOH was realized at 98.8% (rate constant of 0.0720 min-1) within 60 min under magnetic field assisted visible light. In neutral media, the positively charged NOR and negatively charged Mn3O4/γ-MnOOH would arrange in an oriented manner in the presence of magnetic field, providing more active sites for NOR during photocatalysis. Moreover, the opposite Lorentz forces contributed to the attractive interactions between NOR and Mn3O4/γ-MnOOH, accelerating NOR degradation with lower active energy. Quenching experiment showed that ∙O2- and h+ played dominant roles in NOR degradation. Attractively, this study shed new lights on an innovative strategy of magnetic field assisted photocatalysis for refractory contaminants remediation from water.