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.