The determination method of sodium nitrate content, sodium nitrite manufacturers tell you

The determination method of sodium nitrate content, sodium nitrite manufacturers tell you

In addition to making finished products in industrial production, sodium nitrate is also a raw material for the production of industrial sodium nitrite. The content of the finished product of sodium nitrate is related to the effect of the product and the quality of the finished product. The determination and analysis of the net content of the finished sodium nitrate was carried out according to GB4553-2002. The principle of the common measurement method is to first measure the content of impurities such as calcium, magnesium, sulfate, sodium carbonate, and then subtract the content of impurities from the total amount is the content of sodium nitrate. This method is more cumbersome and prone to errors. Common measuring methods include redox method and ferrous ammonium sulfate reduction method. These methods have certain shortcomings. In the determination, there is a new method to test the content of sodium nitrate.

The specific distance is that sodium nitrate in the presence of concentrated sulfuric acid, nitrate and urea will undergo a series of reactions, excess urea will be hydrolyzed into ammonium sulfate under the action of sulfuric acid. The generated ammonium nitrate reacts with formaldehyde to form hexamethylenetetramine. The alkali acid is used to neutralize the acid produced, and the content of sodium nitrate is calculated according to the volume of the consumed alkali standard solution.

Reagent preparation: The mass fraction of urea should not be less than 99%, the standard solution of sodium hydroxide is 0.5% L, the mass concentration of formaldehyde is 0.18% L, and the distilled solution containing 37% to 40% of the formaldehyde mass fraction is diluted to a mass concentration of 180 g L, phenolphthalein ethanol easy mass concentration 10g / L, hydrochloric acid solution 1 + 200, sodium nitrate sample, mass fraction 99.10 &.

Experimental method: Weigh 0.2 ~ 0.5g of sodium sample in a 250ml Erlenmeyer flask, add 0.2 ~ 0.6g of urea, add 5 ~ 10ml of concentrated sulfuric acid, shake and place on an electric furnace to heat until a large amount of white smoke is generated. After cooling, rinse the inner wall of the bottle with a small amount of distilled water until it is clean. Add 1 drop of methyl red indicator, slowly drop 5mol / L sodium hydroxide standard solution to neutralize the solution to yellow, transfer to a 250ml volumetric flask, and bring up to volume with water.

Using a pipette, take 50ml of the above test solution in a 230ml Erlenmeyer flask, add 1 drop of methyl red indicator, neutralize with hydrochloric acid (1 + 200) until orange red, then add 8ml of 180g / l medium formaldehyde solution, shake well Put it for 5 minutes, add 3-5 drops of phenolphthalein indicator, titrate with 0.1mol / L sodium hydroxide standard solution until the solution is pink, and it will be the end point without fading within 30s. From this, the exact content of sodium nitrate can be calculated.

This method determines that the measurement result is compared with the national standard GB4553-2002. The relative error meets the requirements and has a higher precision. The time-consuming time is within 30 minutes. Compared with the national standard method, which takes 4 small poems, it has a greater advantage. It can be used for the determination of nitrate and ammonia nitrogen in nitrophosphate fertilizer.