In this work, the Fe₃O₄ nanoparticles from natural iron sand were doped with Mn and combined with reduced-graphene oxide (rGO) to obtain Mn_xFe_3–xO₄/rGO nanocomposites with mole fraction variations of the Mn of 0.25, 0.5, and 0.75. The crystalline phase of the synthesized Mn_xFe_3–xO₄/rGO nanocomposites formed an amorphous phase. The presence of rGO was observed through EDX results. The magnetical properties of Mn_xFe_3–xO₄/rGO nanocomposites were shown by decreasing the Br, H_cJ, H_max along with increasing of Mn doping. Interestingly, increasing rGO and Mn composition made the absorption bandwidth of the Mn_xFe_3–xO₄/rGO nanocomposites wider, so that the radar absorption also increased marking by the greater reflection loss that reached −11.95 dB. The increase in the radar absorption performance of Mn_xFe_3–xO₄/rGO nanocomposites came from the efficient complementarity between dielectric loss and magnetic loss and interfacial polarization between Fe₃O₄ doped Mn and rGO.

Industrial wastewater contains non-biodegradable dyes that are highly toxic to humans and aquatic life. As solution from photocatalytic degradation, TiO₂ is one of the effective photocatalysts for wastewater degradation, but it has low adsorption power. To overcome this deficiency, this study synthesized a new photocatalyst by Fe-TiO₂/zeolite H-A. The photocatalyst was successfully synthesized by the impregnation method and was systematically characterized by XRD, XRF, SEM, FT-IR and UV-Vis DRS. XRD diffractogram at 2θ = 25.3° showed anatase phase of the photocatalyst. SEM results showed a rough and soft surface with a size of 491.49 nm. FT-IR analysis obtained the zeolite-A characteristic band, vibration of Ti-O-Ti groups and the vibration of the Fe-O group. The bandwidth of the band gap was 3.16 eV. The photocatalytic efficiency of methylene blue degradation reached 89.58% yield with optimum conditions: irradiation time of 50 min, pH 9 and concentration of methylene blue about 20 mg/L. Fe-TiO₂/zeolite H-A as a new photocatalyst can be an alternative photocatalyst to purify methylene blue.