Morphology controlled fabrication of porous magnesium oxide nanostructures for the efficient elimination of methyl orange

Magnesium oxide-based adsorbents (MGO-A) with different morphologies were synthesized via the hexamethylene tetramine-assisted hydrothermal method. The role of four anions in the reaction system, chloride (Cl ⁻ ), nitrate (NO 3 ⁻ ), sulfate (SO 4 2⁻ ), and acetate (C 2 H 3 O 2 2⁻ ) was systematically investigated to determine the properties of the MgO. Standard characterization techniques were used, such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and surface area and pore size interpretations. The kinetics and adsorption isotherm were studied for removal of the dye methyl orange. The dye’s rapid removal led to equilibrium being reached within 5 min. The correlation coefficient values indicate more applicability of pseudo-second-order kinetics than the pseudo-first-order kinetics. Both physisorption and chemisorption can be a pathway towards successfully removing methyl orange. The adsorption isotherm shows that the maximum capacity of the material is very high, 1,062 mg/g for MGO-A. In light of these results, it appears this material holds promise as a dye removal material.