Sodium hydroxide (caustic soda) is a white solid substance having the form of granules or fused mass, which has hygroscopic properties. When dissolved, it tends to produce heat. Due to the strong destructive effect on fabrics, skin and other organic substances, caustic soda (formula NaOH) is called “caustic alkali” or “caustic sodium”, and in industrial plants - “caustic”. In the liquid state, usually colored or colorless liquid in which a precipitate may form.
Caustic soda: application
Caustic soda (sodium caustic) is used for domestic needs, as well as in various industries. This is the most common alkali.
Caustic soda has found application in the following areas:
- caustic soda - registered food additive E524, which is used for the production of ice cream, chocolate, various beverages, as a softening agent for olives, etc.
- in the pulp and paper industry (production of cardboard, various types of paper, wood fiber boards, artificial fibers and much more);
- for the production of biodiesel fuel, which is made from vegetable oils;
- in the chemical industry (for the manufacture of detergents, the neutralization of oxides and acids, for the titration of aluminum, for the production of oils and other things);
- in light industry (for bleaching fabrics, in the production of silk);
- in the automotive industry (used in the manufacture of alkaline batteries);
- in the food industry (for washing equipment; processing and food production).
Caustic Soda Production
The most common way to obtain sodium hydroxide is electrolysis of an aqueous solution of halite (NaCL). The chemical reaction takes place with the accompanying release of hydrogen and chlorine.
Often, caustic soda is produced by electrolysis using polymer or asbestos cathodes (membrane and diaphragm methods), more rarely produced by electrolysis with a mercury cathode.
The most convenient method is the mercury production method, where the cathode is metallic mercury.
Using a high overvoltage coefficient on hydrogen mercury, sodium ions at the cathode are discharged, and as a result sodium amalgam is obtained, which decomposes in hot water. The result is a very pure NaOH, because it contains no impurities. However, this method is considered to be very harmful, since the use of metallic mercury causes environmental pollution.
Membrane and diaphragm methods are more efficient, not costly. They are often used throughout the world.
Caustic soda, depending on its type, can be packaged in various ways. In the solid state, it is assembled into steel drums. The solution of caustic soda is poured into special automobile containers and railway tanks.
Liquid soda is stored indoors in sealed containers resistant to alkalis. Solid sodium hydroxide is stored packed in closed unheated warehouses.
Carry caustic soda using transport (rail, road and water). When delivering solid sodium hydroxide, this product is packaged in bags, and the liquid substance is transported in special railway tanks and tanks. When transporting caustic soda, heat and moisture should be avoided.
Guaranteed shelf life of sodium hydroxide from the date of manufacture - 1 year.
More than 58 million tons of caustic soda are mined and used throughout the year. This substance has a specific gravity of 2.13, can be well dissolved in water (at a temperature of 0 degrees - 43%), but not soluble in dichloroethane. Sodium hydroxide is used to manufacture degassing solution No. 2, in addition, the substance is used for the degassing of the area. Ammonia-alkaline solution No. 2 consists of the following components:
This solution conducts the degassing of military equipment, military vehicles, and various weapons that have become contaminated with such poisonous substances as, for example, sarin.
Ammonia and monoethanolamine are used as degassing agents, as well as to reduce the freezing point of the composition to - 40 ° C. This solution is stored in iron barrels, the volume of which is 100 and 250 liters, and they are transported to the location of military units and production.
Concentrated solution can destroy shoes and fabrics, as well as corrode the skin of people.
When handling this substance must not forget the danger that it might contain. Caustic soda (formula NaOH) caustic, corrosive, 2nd class of danger. When you work with it is necessary to observe all necessary precautions. The substance hit in eyes or on skin can cause serious chemical burns.
If sodium is caustic on the mucous surface, the affected area should be immediately rinsed with running water, and in case of contact with the skin, wipe with acetic acid solution.
When working with caustic sodium, it is recommended to use protective equipment:
- chemical splash goggles (for eye protection);
- rubber gloves (for hand protection);
- rubberized suit or overalls soaked in vinyl (to protect the body).