99.95% blue tungsten oxide nanopowder’s NH3 content is reasonably controlled to better ensure the stable phase composition of blue tungsten oxide, which is the method for controlling the stability of BTO on phase composition since the 1990s. In the 1980s, the quality control of blue tungsten oxide producing process was based on controlling the oxygen index to ensure the stability of phase composition of blue tungsten oxide. Currently, domestic and foreign customers have different requirements for NH3 content. Some requests NH3% <0.3%; Some requires NH3% at the range of 0.3%~0.5%; And the others require NH3% between 0.6% and 0.9%.
Measuring Principle of NH3 Content in 99.95% Blue Tungsten Oxide Nanopowder
NH3 exists in blue tungsten oxide in a compound state and a free state. An excessive amount of alkali liquor is added in blue tungsten oxide to make all ammonia dissociated, and heat the liquor to make ammonia distilled. The distilled ammonia is absorbed by acid at known concentration. The excess acid is then neutralized with alkali and the NH3 content is calculated based on the actual consumption of acid.
Absorption reaction: 2NH3+H2SO4=(NH4)2SO4
Titration reaction: H2SO4+2Na0H=Na2SO4+2H2O
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