▎ 摘　　要

In the present research, two magnetic nanophotocatalysts (MNPCs) including iron oxide nanoparticles decorated with zinc sulfide quantum dots (Fe3O4@ZnS QDs), and N,S- doped graphene QDs (Fe3O4 @ N, S-GQDs) were synthesized by the sonochemical and hydrothermal methods, respectively. The prepared MNPCs were characterized by various techniques including X-Ray Diffraction (XRD), field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometer (VSM), UV-vis absorption and Fourier transform infrared (FT-IR) spectroscopy. The SEM images show the formation of nano- sized particles of Fe3O4, also the morphology and size of the particles were changed after their decoration with ZnS and GQDs. The magnetic saturation values of Fe3O4@ZnS QDs and Fe3O4 @ N, S-GQDs samples were obtained as 19.43 and 55.58 emu.g(-1), respectively. The desirable paramagnetic properties of the samples provide suitable magnetic separation process and simple recyclyig of MNPCs. The photocatalytic activity of the as-synthesized samples was evaluated through investigating their ability to degrade an organic pollutant (i.e. Victoria Blue R dye) in aqueous media. The photodegradation efficiency was evaluated based on the decrease of VBR concentration at its maximum absorption wavelength, in the presence of Fe3O4@ZnS QDs and Fe3O4 @ N, S-GQDs as nanophotocatalyst and under ultraviolet (UV) and visible (Vis) light irradiations, respectively. In optimization experiments, the effect of various factors including pH, dye concentration, irradiation time, MNPC dosage, type and concentration of salts were investigated. The maximum photodegradation percentage of Fe3O4@ZnS QDs was obtained as 93.44 % at pH 8, and in the case of Fe3O4 @ N, S-GQDs as 96.68 % at pH 9, after 120 min irradiation.