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Crystalline aluminum chloride (AlCl3 · 6H2O), crystalline magnesium chloride (MgCl2 · 6H2O), ammonia precursor sol raw material preparation , vacuum freeze- drying method of preparing nanometer magnesium hydroxide fine powder , by transmission electron microscopy (TEM) , X-ray diffraction (XRD), fourier transform infrared spectrometer instrument, such as physical adsorption method of nano -magnesium hydroxide superfine powder characterization. By chemical analysis, the effects of different Mg molar ratio, time , temperature and PH value and other factors on magnesium hydroxide adsorption properties of the sol , the results showed that: 1 . Sol preparation of nanoparticles is a prerequisite . In magnesium hydroxide sol parameters , PH value is the key factor , this was found only when the pH value greater than 8.5 in 10.0 , the gel can be melted to form a sol gel properly , there is the best sol pH range of 9.0 to 9.2 . The ratio of the raw material composition of the product , and when the raw material is less than 3:1 Mg , the product is Mg2Al (OH) 7 and Al (OH) 3 mixture ; with Mg ratio increases the raw material , the product of the Al (OH) 3 the relative content decreased , when the raw material of Mg ratio of 3:1 , the product all of Mg2Al (OH) 7. 2. vacuum freeze drying of the product prepared by the method of Mg2Al (OH) 7 powder Movement flake morphology , particle size less than 30nm, the size distribution. After the powder at 400 ℃ Hou Nami increased specific surface area , 400 ℃ later, with the heat treatment temperature increases, the specific surface area of ??nano-powder began to decline , 900 ℃ after the specific surface area decreased rapidly. 3 with the adsorption time, the adsorption capacity increases, the adsorption can be completed within 40min . Magnesium hydroxide nano materials for heavy metal ions Cr3, Fe3 there was a clear adsorption , adsorption effect on Mn2 poor. 4. Mg / Al molar ratio of 3:1 , the temperature is 45 ℃, pH 9.2 , the nano- aluminum magnesium hydroxide on Cr3, Fe3, Mn2 adsorption best results.
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