Fine blue tungsten oxide is a blue powder with the grain size of 7~12μm.
Basic Measurement Principle of Oxygen Index in Blue Tungsten Oxide
The oxygen index is used to characterize the change of the number of oxygen atoms in blue tungsten oxide (BTO), that is, to reflect whether the content of tungsten contained in BTO powder is high or low. The larger the value, the lower the content of tungsten in blue tungsten oxide, and vice versa.
The determination of oxygen index in blue tungsten oxide is based on the fact that it can be dissolved in potassium hydroxide and a certain amount of potassium ferricyanide solution to generate potassium tungstate (K2WO4). The reaction equation is as follows:
WO3-x+2xK3[Fe(CN)6]+2(x+1)KOH→K2WO4+2xK4[Fe(CN)6]+(x+1)H2O
Excessive potassium ferricyanide reacts with potassium iodide in an acid solution to release iodine. The reaction equation is as follows:
2K3[Fe(CN)6]+2KI→2K4[Fe(CN)6]+I2
Then, titrate with sodium thiosulfate standard solution to calculate the oxygen index in blue tungsten oxide. The reaction equation is as follows:
I2+2Na2S2O3→Na2S4O6+2NaI
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