Sodium Nitrite

Brief Overview

Sodium nitrite is an inorganic compound with the chemical formula NaNO₂ and is the sodium salt of nitrous acid HNO₂. It forms white to slightly yellowish crystalline powder in the pure state. Sodium nitrate is hygroscopic and very soluble in water. It can be found in nature in several vegetables, such as spinach, parsley, lettuce, broccoli, curly kale, and asparagus. It also can be found in the human body to control bacteria in the stomach and prevent gastroenteritis.

Manufacturing Process

The manufacturing process of sodium nitrite is by reacting sodium hydroxide with nitrogen dioxide and nitrogen monoxide. The product of this reaction is sodium nitrite and water. Sodium carbonate also can use as a sodium hydroxide substitute. The overall reaction of manufacturing sodium nitrite is shown below:
 2NaOH + NO₂ + NO → 2NaNO₂ + H₂O

The manufacturing process of sodium nitrite comprises the steps:

1. Absorption of nitrogen oxide in sodium hydroxide or sodium carbonate liquid

Nitrogen dioxide and nitrogen monoxide can be obtained from the manufacturing process of ammonia. It is preferable to use excess nitrogen oxide than nitrogen dioxide to increase the production of sodium nitrite and minimize the production of sodium nitrate. The absorption reaction of nitrogen dioxide and nitrogen monoxide in sodium hydroxide produces a sodium nitrite solution.

2. Evaporation

Sodium nitrite solution that obtained and then being cooled to crystallize. The product is suspensions that contain solid crystalline sodium nitrite in water. To increase the concentration, the suspension is heated until containing water evaporates. The evaporation process separates crystalline sodium nitrite from the mother liquor.

Food Industry

Sodium nitrite has mainly been used as a food stabilizer and additive since the 1990s. As a food preservative, it prevents the growth of bacteria, such as Clostridium botulinum, that can cause botulism disease. Sodium nitrite also added colour and taste to the non-vegetable food. Sodium nitrite can be found in fish and meat bacon, such as smoked fish, hot dogs, and luncheon meats. For safety, the use of sodium nitrite as a food additive is limited to a certain amount.

Pharmaceutical Industry

In the pharmaceutical industry, sodium nitrite treats several diseases and organ damage. Sodium nitrite can prevent cell death in a damaged organ such as the heart, lungs, and liver. It is also used as a treatment for brain aneurysms, pulmonary hypertension, and Pseudomonas aeruginosa. Another use of sodium nitrite is to treat cyanide poisoning. But now, it has been replaced by hydroxocobalamin.

Agriculture Industry

Sodium nitrite is used as fertilizer and a pesticide for several plants. In fertilizer, sodium nitrite increases the amount of nitrogen required for plant growth. It also strengthens the roots and prevents soil erosion. Insecticides, predacides, and rodenticides are examples of pesticides that use sodium nitrite. Sodium nitrite does not directly harm pests and is environmentally safe.

Other Application

Other applications of sodium nitrite are the manufacturing of nitroso compounds, metal coatings for detinning and phosphating, corrosion inhibitors, photography, an inhibitor of polymer, pulp and paper industries, lubricants, industrial and household cleaners, anti-freeze liquid, rubber processing, raw material for caffeine and saccharine production, water treatment, etc. Moreover, Sodium nitrite is often used as a dyeing and bleaching agent in the textile industry.