Background and Objective: In this work, the precipitation combined with vacuum
drying and supercritical CO2 drying was applied in the preparation of Mg(OH)2 which was
thermally decomposed to MgO.
Results: Results showed that the constant dropping rate of Mg(NO3)2 solution into NaOH
aqueous solution under 90°C with a relatively high pH of 10.1 led to the MgO powder with
high specific surface area and large pore volume with both vacuum drying and supercritical
drying. Among the produced MgO, the pore volume1.45 cm3/g from the vacuum drying was
the highest, and the bulk density 0.0247 g/ml from the supercritical drying was the lowest in
the reported literature.
Conclusion: Particularly, the MgO produced from the supercritical drying showed high adsorption
of Pb2+ (as high as 3635 mg/g at pH=6 and 25°C) and Mn2+ (as high as 861 mg/g at
pH=6 and 25°C). The adsorption isotherms and kinetics of Pb2+ and Mn2+ on the produced
MgO were fitted well to the Langmuir model and pseudo-second order model.