Introduction Environmental pollution caused by personal care products and synthetic substances become worse. Bisphenol A (BPA) as a type of endocrine disrupting chemical is detected in water, soil, air, urban waste and food. BPA is difficult to be removed from water body due to its strong biological toxicity and environmental persistence, so it is beneficial to designing the related efficient treatments. At present, main methods removing BPA include adsorption, nanofiltration, photochemical oxidation and electrochemical oxidation, in which photocatalytic oxidation technology has received much attention. TiO2 is extensively investigated due to its advantages. Although TiO2 has an excellent photocatalytic performance, it has significant drawbacks, such as low visible light utilization and easy recombination of photo generated carriers. Loading is an effective method to improve photocatalytic capability. In this paper, Fe3+/CDs-TiO2 composite photocatalyst was prepared by a sol-gel method. Methods For the preparation of Fe3+/CDs-TiO2 catalyst, Ti(OBu)4, anhydrous ethanol and acetic acid were mixed under stirring to obtain a transparent solution. CDs and Fe(NO3)3·9H2O were added into the solution under stirring until forming a gel. The gel was heated in an oven at 70 ℃ to obtain yellow particles. The particles were ground into the finer particles and calcined in a muffle furnace at 300 ℃ for 4.5 h, hence obtaining Fe3+/CDs-TiO2. The photocatalytic performance of Fe3+/CDs-TiO2 was analyzed with BPA as a target pollutant. Fe3+/CDs-TiO2 was added into BPA aqueous solution, stirred in a dark environment for 20 min to achieve adsorption equilibrium. The photocatalytic reaction occurred after turning on an Xenon lamp. The concentrations of samples taken at regular intervals were determined by the HPLC method. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet visible diffuse reflection spectroscopy (UV-Vis DRS) and electrochemical method.Results and discussion Compared with TiO2, the absorption spectra of Fe3+/CDs-TiO2 range to visible light zone and photoinduced electrons transfer quickly through interface chemical bonds, indicating that the co-doping of Fe3+/CDs boosts a photocatalytic efficiency. The degradation efficiency of BPA can be 92.8% after 120 min with Fe3+/CDs-TiO2 at a loading ratio of Fe3+/CDs of 0.5% or 1.5%. Fe3+/CDs-TiO2 has a satisfied stable and reusable performance for 86% BPA, which is still degraded after 7 cycles. The photocatalytic degradation process of BPA with Fe3+/CDs-TiO2 follows the first-order kinetic equation, and the reaction rate constant is 0.022 16 min-1. Based on the results of free radical capture experiments, the holes are the dominant species for BPA degradation, and the toxicity of the intermediates decreases, which is simulated by Toxicity Estimation Software Tool (T.E.S.T). The mechanism of Fe3+/CDs-TiO2 photocatalytic degradation of BPA was analyzed based on main degradation substances and dominant intermediates. There is an electron coupling phenomenon between the orbital and the conduction band of TiO2, forming Ti—O—C bonds. Electrons can quickly transfer from the TiO2 conduction band through Ti—O—C bonds at the interface to the surface of the composite catalyst, and react with dissolved oxygen to generate ·O2-. The holes on the valence band can directly react with organic molecules or form hydroxyl radicals, which almost decompose organic molecules. In addition, the photogenerated electrons on the conduction band also reduce the loaded Fe3+ in-situ to Fe2+, which reacts with dissolved oxygen to generate Fe3+and ·O2-. The Fe3+→Fe2+→Fe3+ microcirculation effectively transfers photogenerated electrons.Conclusions The co-modification of Fe3+ and CDs widened the spectral response range of TiO2, and formed interface chemical bonds that provided channels for photoelectron transfer, suppressing carrier recombination and improving photocatalytic efficiency. When the loading amounts of Fe3+ and CDs were 0.5% and 1.5%, respectively, the composite material had the optimum degradation performance. In the presence of visible light, the degradation efficiency of BPA could reach 92.8% after 120 min. After 7 cycles, Fe3+/CDs-TiO2 still performed well and degradation efficiency was 86%. Fe3+/CDs-TiO2 photocatalytic reaction of BPA followed the first-order reaction kinetic equation, with a reaction rate constant of 0.022 16 min-1. According to the results of free radical capture experiments, the holes were the main species for the degradation of BPA, and the toxicity of the photocatalytic degradation products gradually decreased.