<p>Bi(III)/g-C₃N₄ and Bi(V)/g-C₃N₄ composites were synthesized via microwave irradiation using different weight ratios of Bi₂O₃/g-C₃N₄ and KBiO₃/g-C₃N₄ (20, 50, and 80 wt%). The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), N₂ physisorption, and UV–visible (UV–vis) spectroscopy to determine their composition, structure, morphology, surface area, and optical properties. Photocatalytic activity was evaluated through the degradation of ciprofloxacin under irradiation of a Xenon lamp (35 W). XRD analysis confirmed the formation of crystalline phases in all composites after microwave treatment. SEM images showed improved dispersion of KBiO₃ on the g-C₃N₄ surface compared to Bi₂O₃. In the Bi₂O₃/g-C₃N₄ series, photocatalytic performance increased with Bi₂O₃ content, with the 80 wt% Bi₂O₃ sample achieving 54% degradation and 30% mineralization of ciprofloxacin. Reactive species trapping experiments further revealed that in the 80BiO composite, photoinduced holes (h⁺) are the predominant species responsible for ciprofloxacin oxidation, whereas in the 80KBiO composite, the redox process is mainly governed by the in-situ generation of H₂O₂.</p> Graphical Abstract <p></p>