In this study, a novel magnetic nanocomposite (Ba-α-Bi2O3-γ-Fe2O3) was successfully synthesized through a combination of ultrasound and co-precipitation method under mild conditions. The structure of the synthesized nano-composite as a visible light photocatalyst was investigated by the X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), energy dispersive X-ray spectroscopy (EDX), vibrating sample magnetometer (VSM) and photoluminescence (PL). The HRTEM confirmed that the nano-magnetic composites are rods with diameters of 10-12 nm and lengths of 100-200 nm. The photocatalytic activities of Ba-α-Bi2O3-γ-Fe2O3, α-Bi2O3- γ-Fe2O3, α-Bi2O3 and γ-Fe2O3 were compared by the degradation efficiency of amoxicillin as an antibiotic drug under solar light. On the basis of the results, amoxicillin in aqueous solution was more efficiently photodegraded using Ba-α-Bi2O3-γ-Fe2O3 as nanocomposite under solar light irradiation. The degradation reached to 99% and the mineralization reached to 55% within 2 h under sunlight. In addition, the results of degradation were fitted to the first-order kinetics model and the kinetic constant was 0.017 min-1 with a half-life time of 40 min. On the basis of the performed experiments, the photogenerated electrons played an important role in the decomposition process. In addition, it was confirmed that the formation of oxidative species such as singlet oxygen and superoxide radical in the presence of oxygen are the major factors in the destruction.

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