Sodium Nitrite (NaNO₂) 7632-00-0

Sodium Nitrite (NaNO₂) is a white to slightly yellow crystalline inorganic salt with a molecular weight of 69.00 g/mol. It is highly soluble in water, hygroscopic, and functions as a strong reducing agent. It is produced by reacting nitrogen oxides with sodium hydroxide or sodium carbonate solution and is primarily used in concrete admixtures, metal treatment, dye manufacturing, and chemical synthesis.

Sodium nitrite is a calcium nitrite-based corrosion inhibitor for reinforced concrete. The nitrite ions react with the ferrous ions on the steel surface to form a passive, protective gamma-Fe₂O₃ film that is resistant to chloride ion attack. This prevents the initiation and propagation of rebar corrosion, significantly extending the service life of concrete structures exposed to de-icing salts, marine environments, and other chloride sources.

In metal treatment, sodium nitrite is used as a component in phosphating solutions to produce corrosion-resistant phosphate coatings on steel and iron surfaces. It serves as an accelerator in zinc and manganese phosphating processes. It is also used in heat treatment salt bath formulations for nitriding and as a rust inhibitor in cooling water systems and metalworking fluids.

Yes, sodium nitrite can be used as a cold-weather concreting admixture. It accelerates cement hydration at low temperatures while simultaneously providing corrosion protection to embedded steel. This dual function makes it particularly valuable for winter concrete construction in regions where both cold temperatures and de-icing salt exposure are concerns.

Sodium nitrite is toxic if swallowed and can be fatal in relatively small doses. It is a strong oxidizer and can intensify fires when in contact with combustible materials. It should be stored in a cool, dry, well-ventilated area in tightly sealed containers, away from reducing agents, acids, ammonium salts, and combustible materials. Use appropriate PPE including gloves and eye protection. Do not eat, drink, or smoke when handling. Under proper storage conditions, shelf life is 12-24 months.