Efficient peroxymonosulfate activation by Fe–BiOCl hollow microspheres for carbamazepine removal†

The preparation of highly effective and stable photocatalysts for visible-light-driven activation of peroxymonosulfate (PMS) to remove refractory organic contaminants is an attractive study. Herein, a series of Fe–BiOCl photocatalysts with a hollow structure were prepared through a regular one-step solvothermal approach and applied to activate PMS for carbamazepine (CBZ) degradation. Benefiting from the synergistic effect of photocatalysis and PMS activation, the 3% Fe–BiOCl/PMS system exhibits a higher CBZ removal ability under visible irradiation, with the corresponding apparent rate constant (k = 0.0449 min⁻¹) being 12 times higher than that of individual BiOCl (k = 0.0037 min⁻¹). Further experiments verify that the doping of Fe and the construction of the hollow structure of BiOCl can improve light absorption and utilization efficiency. More importantly, the introduced Fe³⁺ can facilitate the fast separation of photogenerated carriers and the activation of PMS. Capture experiments and EPR tests demonstrate that multiple active species (OH˙, SO₄˙⁻, ¹O₂ and O₂˙⁻) participate in the PMS activation for the CBZ degradation process, with SO₄˙⁻ being the primary active species. Furthermore, the effects of photocatalyst amount, PMS concentration, initial solution pH, and co-existing anions on CBZ removal were explored. A possible mechanism for the photocatalytic removal of CBZ is also proposed. In addition, the 3% Fe-BOC displays outstanding photocatalytic activity over four consecutive cycles, indicating that it could be a reliable PMS activator for CBZ elimination in practical application. This work provides new ideas for constructing efficient and stable BiOCl-based catalytic systems for visible-light-driven removal of emerging contaminants.