Template synthesis of ordered mesoporous MgO with superior adsorption for Pb(II) and Cd(II)

Ordered mesoporous MgO was synthesized via template method by using magnesium nitrate as a precursor and amphiphilic triblock copolymer Pluronic F127 as a template. The products were characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM), and the Brunauer-Emmett-Teller (BET) method was used to calculate the specific surface areas. The effects of aging time, relative humidity, and magnesium nitrate content on the morphology and textural properties of the products were studied. When the aging time was 36 h and the relative humidity was 40%, the ordered mesoporous MgO with uniform pore sizes (3.2 nm), high specific surface areas (517.2 m²/g), and high pore volumes (0.42 cm³/g) were obtained. Furthermore, the adsorption properties of ordered mesoporous MgO as adsorbent for removal of Pb(II) and Cd(II) ions were studied. The adsorption kinetics and isotherm data agreed well with pseudo-second-order model and Langmuir model, indicating that the adsorption of heavy metal ions on the ordered mesoporous MgO was mainly chemical and homogeneous adsorption. The maximum adsorption capacities for Pb(II) and Cd(II) ions were up to 3073.5 mg/g and 1485.1 mg/g, respectively.