Mechanisms underlying the photocatalytic degradation pathway of ciprofloxacin with heterogeneous TiO2

The presence of antibiotics in different water sources is a ubiquitous, global concern. The persistence of trace amounts of antibiotics can lead to antibiotic resistance of microbial pathogens and jeopardize the health of ecosystems. One possible solution is the photocatalytic degradation of antibiotics from water systems by titanium dioxide (TiO2) photocatalysis. In recent years, heterogeneous TiO2 has been examined for the photocatalytic degradation of ciprofloxacin (CIP) under UV/visible light irradiation. This review offers an overview of the recent advances in visible light-activated TiO2 for the photocatalytic degradation of CIP and the factors impacting the photocatalytic behavior. In particular, we focused on the structural elucidation of reaction intermediates, and we aimed to determine research gaps in the utilization of visible light-activated TiO2 for water treatment. Future research directions, including the ecotoxicological effect of the photocatalytic degradation intermediates, the thermodynamical and kinetic mechanisms of the photocatalytic degradation process, and future applications of heterogeneous TiO2 photocatalysts, are also proposed.