Singlet oxygen mediated photocatalytic Antimonite decontamination in water using nanoconfined TiO2

The development of advanced strategies to decontaminate water polluted with emerging contaminants (e.g., antimony (Sb)) is considered a priority. Herein, we synthesized and evaluated nanoscale photocatalysts with TiO2 confined within and on the outer surface of carbon nanotubes (i.e., TiO2-in/out-CNT) for the simultaneous detoxification of toxic Sb(III) and adsorption of less toxic Sb(V). Under simulated solar irradiation, the TiO2-in-CNT system exhibited a Sb(III) removal efficiency of 100% over 40 min with 1O2 as the dominant reactive species. In contrast, HO• was identified as the species contributed to the Sb(III) conversion in the unconfined TiO2-out-CNT system. In addition, the TiO2-in-CNT system exhibited faster Sb(III) removal kinetics (4 times) compared with that of TiO2-out-CNT. The system efficacy was tolerant of a wide pH range (3.2–9.5), and showed good selectivity and performance in the presence of several coexisting anions (e.g., NO3–, Cl−, HCO3–) and different water matrices. The outcomes of this study are dedicated to providing an effective design for the decontamination of highly toxic heavy metal ions in water by integrating a state-of-the-art nanoconfinement effect and photocatalysis.