Preparation and kinetic study of magnesium oxide nanopowder

This paper briefly introduces the research progress of magnesium oxide nanopowder preparation technology, the mechanism of magnesium oxide nanoparticles formation, the theory of anti-agglomeration in solution and drying process, the theory of thermal decomposition kinetics and the theory of grain growth kinetics of only image.
On the basis of the experiments, the influence law of each process condition on magnesium oxide nanopowders was analyzed, and the orthogonal test table was used to find the key factors affecting the grain diameter and product yield during the preparation of magnesium oxide nanopowders, as well as the better process conditions.

In this paper, the different solvent replacement drying methods, the mechanism of thermal decomposition process, and the kinetics of magnesium oxide nanograin growth were investigated by X-ray diffraction, transmission electron microscopy, infrared spectroscopy, thermogravimetric and differential thermal analysis of nanomaterials. The calcination of Mg(OH) nano-magnesium hydroxide is a process of crystalline transformation and thermal decomposition reaction. It is the conversion from Mg(OH)_2 polycrystal to MgO polycrystal with an amorphous process in between.

When the drying time is 3 hours, between 200℃ and 350℃ is a transitional process, after 350℃, the crystalline shape is more intact. The higher the calcination temperature, the larger the grain size. If the grain diameter is used as the control index, combined with the results of single-factor test, the better process conditions for the synthesis of magnesium oxide nanoparticles are: reaction temperature 95℃, reaction time 3 hours, reactant concentration 2.1 mol/dm~3, reaction ratio 5:1 and soak in 50ml ethanol for 0.5h, drying temperature 100℃, drying for 3 hours, calcination temperature 400℃, calcination for 3 hours.

The results of the orthogonal test showed that the concentration of the reactants had the greatest effect on the grain diameter, and the reaction temperature, reaction time and ratio had less effect on the grain diameter. The reaction temperature had the greatest effect on the yield of magnesium oxide, the reaction time was the second, and the reaction ratio and concentration of reactants had less effect on the yield of magnesium oxide.