A dramatic enhancement of antibiotic photodegradation catalyzed by red mud-derived Bi5FeTi3O15

Abstract The current scale of aluminum production and the accompanying waste disposal problems provide a largely untapped opportunity for chemical upcycling. Herein, red mud was recovered in the process of alumina extraction from bauxite and reutilized as a precursor to obtain layered ferroelectric perovskite Bi5FeTi3O15 (RM-BFTO-M) via a molten-salt growth path. The as-prepared samples were characterized systematically by various techniques. The EDS and XPS results indicate that in addition to Fe element, several elements (Co, Ca, Al) in red mud are also introduced in RM-BFTO-M, while the photocurrent analysis and EIS date reveal the enhanced light absorption and charge separation of RM-BFTO-M relative to comparative Bi5FeTi3O15 sample (BFTO-M). RM-BFTO-M shows superior photocatalytic performance for degradation of tetracycline hydrochloride with the rate of 211.8 times higher than that of comparative BFTO-M. The active species h+ and OH play a crucial role during this degradation process. In order to reveal the enhancement mechanism, Co, Ca and Al elements were artificially doped into Bi5FeTi3O15, respectively. As expected, the enhanced photocatalytic activity is observed in the doping samples. Finally, a potential visible-light driven catalytic mechanism over RM-BFTO-M was put forward. Our work provides new thought for resource utilization of red mud.