Dolomite Homogeneous Precipitation Method And The Method Of The Inverse Microemulsion Method To Prepare Nano Magnesia

Nano-MgO is a new type of high function fine inorganic material. Because of its quantum size effect, small-size effect, surface effect, macroscopic quantum tunneling effect, etc, it has a superior performance to the materials now existing.This paper introduced the current research status on nano-MgO,the theory of homogenous precipitation and micro-emulsion reaction.The nano-MgO crystal was made by the sluggish precipitation method from dolomite and reverse microemulsion methodIn this paper,the dolomite which was native to Dongan Countr y, Yongzhou City of Hunan Province was used to make the nano-MgO by the homogenous precipitation method.And the orthogonal test methodused was used to find the optimum conditions under which the nana-MgO of small size and good dispersion could be obtained.The atomic absorption (AAS), X-ray diffraction (XRD),scanning electron microscopy (SEM) and thermogravimetric (TGA) were used to research the effect of dispersant types, dispersant dosage, precipitant types and solvent on the size of nano-MgO. A discussion was devoted to the mechanism of the impact of every factor with correlate theory. And the research could be usefull for the industrialization of nano-MgO.The optimum technological conditions which was decided by the orthogonal test was:The optimum synthesis condition of nanometer-sized magnesium oxide (MgO) powders investigated by an orthogonal test was that,the urea and amylum as the precipitator and the dispersant separate-ly,and the dosage of amylum was 45% on the condition of ultrasonic vibration 20 minutes at 70℃,and then by the process of the depositi-on,centrifugation,washing,solvent replacement,vacuum drying at room temperature and ultimately calcining. The results indicated that the dispersity of the nanoparticles was well, The crystal size was 12.5nm,they were well-proportioned,the crystallinity was high,and the productive rate reached 86%.This method will have a wide application.A the preparation of nano-MgO via microemulsion method could realize the control of the particle size and the morphology,so micro- emulsion method has become an effective method to obtain nano-MgO, but there were not plenty of Researches dealing with the microemulsion method.reverse micelles were used as microreactors,so reagents disso-lving in the water shell reacted within the shell,and the influences of mass ratio of water to surfactant(w0) on UV-shielding properties of nano-MgO, assembly time,and calcination temperature on the particle size and morp-hologies of product were studied, the structure of the particles were characterized and the formation mechanism was discussed.MgO nanoparticles have been prepared by polyethylene glycol octylphenyl ether(Triton X-100)/n-butyl alcohol/n-heptane/water reverse microemulsion.The result of thermal analysis (TG-DTG-DTA) of the precursor products showed that the proper calcination temperature was 600℃.The structures and morphologies of MgO nanoparticles were char-acterized by X-ray powder diffraction(XRD),Scanning electron micro-scope(SEM) and UV-vis spectrophotometry.The influences of mass ratio of water to surfactant(w0) on UV-shielding properties of nano-MgO, assembly time,and calcination temperature on the particle size and morp-hologies of product were studied,and the formation mechanisms in the reverse microemulsion were also discussed.The results show that the obtained MgO powder has no obvious agglomeration and narrow particle size distribution under the condition of mass ratio of water to surfactant wo= 15,calcination temperature r=600℃, assembly time of 15 h, reaction temperature t=30℃.