Forms of sodium nitrite and impurity profile thereof

A method of obtaining an improved form of purified crystalline sodium nitrite with minimum impurities consisting steps of:

• mixing of air and ammonia in a venturi body mixer;
• transmitting the air-ammonia mixture through a HEPA filter for filtering out impurities and to obtain a purified air-ammonia mixture;
• transmitting the mixture of air-ammonia into the adiabatic burner to pass through a plurality of catalytic gauzes positioned as three pairs of two gauzes each at a temperature between 150° C.-170° C. to carry out the selective oxidation process and to selectively obtain oxides of nitrogen;
• saturating oxides of nitrogen using a waste heat recovery boiler (WHRB) to obtain a saturated NO2 gas;
• passing a saturated NO2 gas through one or more absorption towers for absorbing the saturated NO2 gas in one or more absorption towers containing an alkali medium for selective formation of sodium nitrite slurry;
• optimizing a concentration of sodium nitrite slurry at a temperature between 85-90° C. under stirring to obtain a crude crystalline form of SNI;
• re-crystallizing the crude crystalline form of SNI by multiple washing of a water solvent for removing the maximum impurities;
• and
• obtaining the improved form of purified crystalline SNI with a purity level between 99% to 99.2%.