In this research, the magnetic Fe₃O₄/zeolite NaA nanocomposite (Fe₃O₄/ZA), Fe₃O₄ nanoparticles, and zeolite NaA have been synthesized by facile hydrothermal methods for adsorption removal of methylene blue from aqueous solution. The as-synthesized Fe₃O₄/ZA nanocomposite was characterized by X-ray diffraction (XRD), MicroRaman analysis, Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray fluorescence (XRF), N₂ adsorption isotherms (BET), and UV-VIS analysis. The results show that with a small weight loading of Fe₃O₄, the 3.3 Fe₃O₄/ZA sample exhibits a high adsorption capacity (40.36mg·g⁻¹) and removal efficiency (96.8) compared to that of the zeolite NaA (32.99mg·g⁻¹ and 79.11, respectively). Interestingly, the removal efficiency and the adsorption capacity increase rapidly with the increase of adsorption time (1060 minutes) and Fe₃O₄ loading (3.39.3 wt.) in the Fe₃O₄/ZA composition. The adsorption mechanism of MB molecules of the Fe₃O₄/ZA can be addressed at the combination of the interaction between active sites on the surfaces and edges of the invert spinel ferrite Fe₃O₄ nanoparticles and zeolite NaA with MB molecules. Our approach provides a simple, efficient, and scalable synthesis process that render practical applications of the magnetic Fe₃O₄/ZA nanocomposite as a lower-cost adsorbent for wastewater treatment.

In this research, ZnO/GO nanocomposites were successfully synthesized by a simple hydrothermal method using graphene oxide (GO) and zinc acetate dihydrate (Zn(CH₃COO)₂.2H₂O) as the reactants. The effect of the hydrothermal reaction time on the structure and optical property of the ZnO/GO was systematically investigated. The structure, morphology and chemical composition of the samples were measured by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and Raman and Fourier transform infrared (FTIR) spectroscopy, while the optical properties were measured using photoluminescence spectroscopy. The synthesized products consisted of large quantities of one-dimensional (1D) ZnO nanorods (NRs), which were dispersed uniformly on the GO surface. The XRD and Raman results reveal that the ZnO NRs in the fabricated samples had a hexagonal wurtzite structure with high crystalline quality. The FESEM and TEM images reveal that ZnO NRs with an average diameter in the range of ~85–270 nm and length in the range of ~0.3–6 μm were covered with GO sheets. Additionally, it was found that the crystallographic orientation of ZnO NRs was dependent not only on the hydrothermal reaction time but also on the presence of GO in the nanocomposites. However, the addition of GO did not affect the stoichiometric ratio and the crystal structure of ZnO NRs. The room-temperature PL results indicated that, compared to those of pure ZnO, the luminescence of the GO/ZnO nanocomposites was suppressed and shifted towards a higher wavelength (red shift), which was attributed to the incorporation of ZnO NRs within the GO matrix and the formation of a C-O-Zn chemical bond in the nanocomposites. The hydrothermal technique is considered one of the best routes due to its low cost, high growth rates, low-temperature synthesis, controllable crystallographic orientation, particle size, as well as morphology.