| Summary: | Ag/Au/Fe3O4/graphene composites prepared by a hydrothermal method demonstrated excellent activation of H2O2 and were used to degrade methylene blue (MB) in solution in the presence of organic acids and inorganic ions under light and ultrasound irradiation. The physicochemical properties of the obtained composites were characterized using various methods. The results showed that the composites exhibited excellent magnetic properties, crystallinity, and stability. The results of catalysis experiments revealed that the removal efficiency of MB increased when Ag and Au were both incorporated into the Fe3O4/graphene/H2O2 system compared with the removal efficiency achieved with separate Ag-Fe3O4/graphene/H2O2 and Au-Fe3O4/graphene/H2O2 systems, indicating a substantial synergistic interaction between the two metallic nanoparticles and the Fe3O4/graphene/H2O2 systems. The presence of an organic acid accelerated degradation of the MB/H2O2 system, whereas almost all of the investigated anions inhibited the degradation of MB; their inhibition effects followed the order CO32− > NO3− > Cl− > F− > H2PO4− > SO42− > I−. Cations of Na+, K+, Ca2+, and Mg2+ also suppressed MB degradation, likely because of the influence of Cl− coexisting in the solutions.
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