Magnesium hydroxide and magnesium oxide are widely used in medicine, energy, aerospace, food, daily chemical, catalyst, refractory, flame retardant, heavy metal removal, smoke desulfurization, acid waste liquid neutralization and other fields. Among them, nano-grade magnesium hydroxide, magnesium oxide products have the highest added value. With our country becoming the second largest economy in the world, the demand for nanoscale magnesium hydroxide and magnesium oxide will be more and more, and its market prospect is very broad.
In this paper, magnesium hydroxide nano powders, magnesium oxide powders and doped nano powders with various morphologies were prepared by chemical precipitation method using inorganic magnesium salts as raw material, ammonia as precipitant, PEG1000 as crystal control dispersant and titanium and zinc as dopants. The physical phase, structure, composition and morphology of the products were characterized by X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM).
The relevant findings are as follows:
1) From the analysis of the orthogonal experiments and considering the effects on the grain size and yield, the best conditions for the preparation of Mg2+ nanoparticles were Mg2+ concentration 0.2 mol/L, reaction temperature 60°C, reaction time 1.5h, and ammonia dosage more than 10mL.
2) The surfactant PEG has a significant effect on the morphology, structure and grain size of magnesium hydroxide/magnesium oxide. Experiments show that: the best addition of PEG1000 is 0.3-4.0%. Different weight percentages of PEG1000 can be used to produce needle-shaped, flaky and tubular magnesium hydroxide nano powders.
3) The presence of ethanol as the reaction solvent facilitated the crystallization of the oxide and reduced the average grain size of the product. But the crystallization performance of the product is not as good as the product generated by the reaction in the pure water system.
4) Titanium doping can inhibit the crystallization property of magnesium oxide and promote the dispersion of powder particles, which can lead to the formation of titanium-doped magnesium oxide nanotubes.