Insight into the pathway, improvement of performance and photocatalytic mechanism of active carbon/Bi4O5Br2 composite for cefixime and rhodamine B removal

In this work, a cost-efficient activated carbon (Ac)/Bi4O5Br2 photocatalyst was successfully prepared for organic pollutant degradation in wastewater under simulated sunlight irradiation. The crystal structure, surface composition, morphology and optical properties of the prepared composites were systematically characterized by XRD, FTIR, SEM, EDS, SEM, XPS and ESR. The photocatalytic activity of the prepared Ac/Bi4O5Br2 composites was evaluated by the degradation of rhodamine B (RhB) and cefixime under visible light irradiation. Additionally, the Ac/Bi4O5Br2 composites displayed stronger photocatalytic activity compared with pure Bi4O5Br2. Particularly, the 30% Ac/Bi4O5Br2 composite displayed the strongest degradation rate of cefixime and RhB, which is about 2 and 4 times to Bi4O5Br2. Furthermore, the enhanced photocatalytic activity of Ac/Bi4O5Br2 composites was attributed to its stronger adsorption property, improved separation rate of photogenerated charge carriers and light capture ability. The degradation intermediates and pathway of cefixime was analyzed with HPLC-MS. The main actives species in the Ac/Bi4O5Br2 composites are h+, ·O2–, ·OH as analyzed with the multiple techniques. This work provided an alternative strategy to treat the organic contaminants in wastewater with BixOyBrz-based photocatalyst.