Facile synthesis and characterization of magnesium and manganese mixed oxides for the efficient removal of tartrazine dye from aqueous media

Abstract

Nanomaterials are the most effective class of substances for use as adsorbents in wastewater treatment. Hence, the current study involves the facile and low-cost synthesis of MgMn₂O₄/Mn₂O₃ and MgMn₂O₄/Mn₂O₃/Mg₆MnO₈ as novel nanostructures from mixed solutions of Mg(ii) and Mn(ii) ions using the Pechini sol-gel method. After that, the remaining powder was calcined at 500, 700, and 900 °C for 3 h; the products were designated as G500, G700, and G900, respectively. The G500 sample consists of MgMn₂O₄ and Mn₂O₃, while the G700 and G900 samples consist of MgMn₂O₄, Mg₆MnO₈, and Mn₂O₃. The synthesized nanostructures were characterized using several tools, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and N₂ adsorption/desorption analysis. The average crystallite size of the G500, G700, and G900 samples is 210.53, 95.27, and 83.43 nm, respectively. The SEM images showed that the G500 sample consists of square and rectangular bars with an average diameter of 3.18 μm. Also, the G700 and G900 samples consist of hexagonal, polyhedral, and irregular shapes with an average diameter of 1.12 and 0.54 μm, respectively. The synthesized nanostructures were further utilized as adsorbents for the efficient removal of tartrazine dye from aqueous media. The experimental data showed a good fit with the Langmuir isotherm and pseudo-first-order model. The maximum adsorption capacities of the G500, G700, and G900 adsorbents toward tartrazine dye are 328.95, 359.71, and 395.26 mg g^-1, respectively.