In this study, nano-structured manganese oxide compounds doped with gadolinium cations were prepared by effective hydrothermal method. XRD, SEM and DRS absorption spectroscopy techniques were used to identify the synthesized materials. According to the X- ray diffraction patterns, the prepared materials have a spinel manganese oxide crystal structure. The photocatalytic properties of the prepared samples were used and evaluated to remove the methylene blue dye under the photocatalytic and sonophotocatalytic process in aqueous medium. Experiments show that with the increase in the amount of dopant, the percentage of color removal has increased and the highest value obtained for pollutant removal is related to the sample of manganese oxide doped with gadolinium (x=0.08). Also, the role of several factors such as color concentration, catalyst amount and photocatalytic process time were studied.
