A γ-Al2O3 and MgO/MgAl2O4 Fabricated via a Facile Pathway as Excellent Dye Eliminators from Water

This study has successfully developed a practical and straightforward approach for synthesizing nanocomposites with excellent dye removal potential. The SEM inspection of γ-Al2O3 (γ-Al) and MgO/MgAl2O4 (Mg/MgAl) nanocomposite showed a mean size of 59.0 and 46.4 nm, respectively, while the TEM results show particles with an average size of 26.63 and 13.4 nm, respectively. The surface area of γ-Al and Mg/MgAl was 50.0 and 69.5 m2 g−1, respectively. The study of adsorbing indigo carmine (IC) sorption onto γ-Al and Mg/MgAl presented sorption capacities of 41.6 and 55.9 mg g−1, respectively, and both adsorbents attained equilibrium at 90 min. The highest IC sorption onto Mg/MgAl took place at pH 6.0. It is worth mentioning that raising the IC solution’s temperature from 20 °C to 50 °C increased the qt to 268 mg g−1. The IC sorption onto γ-Al and Mg/MgAl agreed with the pseudo-second-order model, and the liquid-film diffusion controlled the IC sorption. The Mg/MgAl showed an average removal of 98.2% when tested for removing six dyes at 10 mg L−1, particularly malachite green, methylene blue, fast green, methyl orange, rhodamine B, and basic fuchsin, and the removal efficiency was 93.3% when their concentration increased to 20 mg L−1. The Mg/MgAl nanocomposite performed exceptionally well in natural water samples (seawater and groundwater), indicating its potential applicability in managing water contamination.