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Synthesis Method of Bismuth Oxide

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Synthesis Method of Bismuth Oxide

1. To the bismuth nitrate solution (80-90°C), dropwise add a carbon dioxide-free sodium hydroxide aqueous solution and mix. The solution remain alkaline during the precipitation process a white, volume-swelling bismuth oxide hydrate Bi(OH)3 precipitates. This solution is heated and stirred for a short time to be the dehydrated into the yellow bismuth trioxide. After washing with water decantation, filtering and drying, the finished bismuth oxide product is obtained.

2. Under a nitrogen atmosphere, add the dropwise a 1.5 mol/L sodium hydroxide aqueous solution without carbon dioxide to a 0.1 mol/L bismuth nitrate solution dissolved in 1 mol/L nitric acid (at 80-90°C) to mix them. The answers remain alkaline during precipitation. Although a white, the volume-expanded bismuth oxide hydrate Bi(OH)3 residues, it is dehydrated and turned into light yellow bismuth trioxide after being stirred in a hot solution. Decant and wash 16 times with water free of air and the carbon dioxide, filter and dry.

3. After the metal bismuth is put into the graphite crucible and then melted, an arc is formed between the graphite electrode and the metal surface to heat and oxidize under the oxygen flow. To ensure an adequate supply of oxygen, the crucible should be placed in a large container, and oxygen should be continuously supplied. The reaction temperature is 760-800°C, and β-bismuth trioxide with a purity of 99.7% or more is fast generated. After the products are quenched in water or on a cold metal plate, the high-temperature phase β-type product can be obtained.

4. Slowly add Bi(NO3)3·5H2O acidic solution (20g dissolved in 2mol/L HNO3) to excess sodium carbonate solution and stir vigorously. Obtain Bi2O3CO3 precipitate, filter, wash, and dry. Please place it in an aluminum boat and heat it in the air at 650K for about 1.5 hours to obtain β-Bi2O3

5. Burn the bismuth subnitrate at the 400~500℃ to remove NO3- ion for about (3~5h):

2BiONO3=Bi2O3+NO+NO2+O2

The burning is over, and then cooling, all turn into the lemon yellow, which is the finished product.

6. Use a small amount of dilute nitric acid to wash 16kg of 99.8% industrial bismuth surface and then use conductive water to clean the nitric acid surface. Then add 1:1 high-purity nitric acid (35kg of nitric acid with the relative density of 1.42 plus 20L of conductive water), use 1 H to complete the addition, and continue to react for 10 minutes after the acquisition. After cooling slightly, it is filtered, the filtrate is heated to 65-70°C, evaporated and concentrated to the relative density of 1.9, cooled and crystallized, and dried to obtain the bismuth nitrate. Dissolve obtained bismuth nitrate with conductive water into a dilute solution, hydrolyze it under stirring, let stand to ultimately precipitate the bismuth subnitrate, spin the residue with the centrifuge or filter with suction, then wash it with thermoelectric conductive water a few times, filter with suction and dry, Pulverize, burn at 500℃ for 7-8h, grind after a little cooling, and burn again for 4-5h. After cooling, 99.99% high-purity bismuth oxide can be obtained.


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Tag: Bismuth Oxide