Fabrication of mesoporous magnesium oxide nanosheets using magnesium powder and their excellent adsorption of Ni (II)

[Display omitted] •Mesoporous MgO nanosheets were synthesized using Mg powder by a hydrothermal method.•The Mg powder slowly generates Mg2+ resulting in a slow nucleation and growth rate of Mg(OH)2.•The adsorption performance of MgO is 2217mg/g. Mesoporous MgO nanosheets with a high adsorption rate and excellent adsorption capacity for removing Ni (II) were successfully synthesized by a hydrothermal and annealing method. The Mg(OH)2 was first synthesized by a hydrothermal process using magnesium powder as the starting material. MgO was then obtained by annealing the as-prepared Mg(OH)2 at 450°C. The advantage of the magnesium powder as the starting material is it slowly generated Mg2+. Thus, the low centration of Mg2+ guaranteed a slow rate of forming Mg(OH)2, which benefited with a mesoporous structure. The effect of the hydrothermal time on the structure and adsorption performance was studied. The results showed that the MgO synthesized for 4h had the highest adsorption performance of 2217mg/g and the highest adsorption rate, which resulted in an efficient adsorption of 96% in 5min for Ni (II) with the concentration of 500mg/L.