Solution Combustion Synthesis of Porous MgO Nanostructures for Efficient Removal of Congo Red

Porous MgO nanostructures were synthesized in large-scale by a simple solution combustion method using citric acid and glucose as the fuel. The resulting porous nanostructure powders were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), and N₂ adsorption–desorption isotherms. The SEM and TEM images demonstrated that the type of fuel used during the combustion synthesis strongly affects the morphology and structure. The use of glucose aggregated the structure with majority particle sizes in the range 3560 nm and a surface area of 40.55 m²g^-1, while the use of citric acid results in a large network structure with smaller particle sizes (30–50 nm) and a larger surface area of 53.88 m²g^-1. The two samples synthesized from glucose and citric acid exhibited excellent adsorption performance for Congo red with the maximum capacity reaching 1500.98 mg g^-1 and 1638.08 mg g^-1, respectively. These results indicate that the porous MgO synthesized by the solution combustion is a potential candidate for the removal of pollutant dye in water.