Superb removal capacity of hierarchically porous magnesium oxide for phosphate and methyl orange

Abstract

Here, we successfully developed a template-free way to fabricate hierarchically porous magnesium oxide (MgO) and carefully investigated the adsorption behavior for phosphate and methyl orange (MO). The average pore size and the percentage porosity decreased with the increase in the feeding ratio of Mg²⁺/NH₃. Among the three samples, MgO-25 shows the highest surface area of 63 m² g⁻¹ determined by the mercury intrusion method, and MgO-50 exhibits the highest BET surface area of 121 m² g⁻¹. For all the MgO samples, the adsorption process follows the pseudo second-order and Langmuir isotherm for phosphate, while pseudo second-order and the Freundlich isotherm for MO. Among the investigated samples, MgO-25 shows the most maximum removal capacity of 478.5 mg g⁻¹ for phosphate and the highest removal capacity of 4483.9 mg g⁻¹ for MO. This study compromises a low-cost and convenient dual function material for excellent water remediation of multiple industries.