Red mud-based biochar activated peroxydisulfate under visible light for tetracycline removal: Synergistic effect of FeAl2O4 photocatalysis

•A catalyst containing FeAl2O4 phase was prepared using rice husk red mud.•The phase change of iron in red mud during pyrolysis was studied.•FeAl2O4 generates cavities which preferentially form 1O2 with PDS in the presence of light.•Red mud-based biochar showed high TCH degradation and mineralization activity.