Sodium hydroxide (caustic soda) is a solid white substance, which has the form of granules or fused mass, which has hygroscopic properties. When dissolving it has the property of releasing heat. Due to the strong destructive effect on the fabric, the skin and other organic substances caustic soda (formula NaOH) is called "caustic alkali" or "caustic sodium", and in the manufacturing plants - "caustic". In the liquid state, as a rule, a colored or colorless liquid in which a precipitate can form.
Caustic soda: application
Soda caustic (sodium caustic) is used for domestic needs, as well as in various industries. This is the most common alkali.
Caustic soda was used in the following areas:
- caustic soda - registered food additive Е524, which is used for the production of ice cream, chocolate, various drinks, as a softening agent for olives, etc.
- in the pulp and paper industry (the 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 production of detergents, neutralization of oxides and acids, for titration of aluminum, for the production of oils and other);
- in light industry (for bleaching fabrics, in silk production);
- in automotive production (used in the manufacture of alkaline batteries);
- in the food industry (for washing equipment, processing and food production).
Production of caustic soda
The most common way of obtaining sodium hydroxide is the electrolysis of an aqueous solution of halite (NaCl). The chemical reaction proceeds with the accompaniment of hydrogen and chlorine evolution.
Often caustic soda is produced by electrolysis using polymer or asbestos cathodes (membrane and diaphragm methods), more rarely obtained by electrolysis with a mercury cathode.
The most convenient method is the mercury production method, where the cathode is metallic mercury.
With the help of a high overvoltage factor on mercury of hydrogen, sodium ions at the cathode are discharged, and as a result, sodium amalgam is obtained, which decomposes in hot water. As a result, very pure NaOH is obtained, because there are no impurities in it. However, this method is considered very harmful, since the use of metallic mercury causes environmental pollution.
Membrane and diaphragm methods are more effective, less expensive. They are most often used throughout the world.
Caustic soda, depending on its kind, can be packed in various ways. In a solid state, it is assembled into steel drums. A solution of caustic soda is poured into special automobile containers and railway tanks.
Storage of substance
Liquid soda is stored indoors in sealed containers, resistant to the action of alkalis. Solid caustic sodium is stored in a packaged form in closed unheated warehouses.
Transfer caustic soda by means of transport (rail, road and water). When carrying out the delivery of solid caustic sodium, this product is packed in bags, and the liquid substance is transported in special railway tanks and containers. When transporting caustic soda, heat and moisture should be avoided.
Guaranteed shelf life of caustic sodium from the date of manufacture is 1 year.
More than 58 million tons of caustic soda are extracted and used throughout the year. This substance has a specific gravity of 2.13, can dissolve well in water (at a temperature of 0 degrees - 43%), but insoluble in dichloroethane. Sodium caustic goes to the manufacture of degassing solution No. 2, in addition, the substance is used for degassing the terrain. Ammonia-alkaline solution No. 2 consists of the following components:
This solution degasses military equipment, military transport, various weapons, which were infected with such poisonous substances as, for example, sarin.
Ammonia and monoethanolamine are used as degassing substances, as well as to reduce the freezing temperature of the formulation to -40 ° C. This solution is stored in iron barrels, the volume of which - 100 and 250 liters, they are transported to the location of military units and production.
A concentrated solution is capable of destroying shoes and tissues, as well as corroding people's skin.
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.
When sodium hydroxide hits the mucous surface, immediately flush the affected area with running water, and if it gets on the skin, wipe it with a solution of acetic acid.
Working with caustic sodium, it is recommended to use protective equipment:
- splash-proof chemical goggles (for eye protection);
- rubber gloves (for protection of hands);
- rubberized suit or overalls, impregnated with vinyl (to protect the trunk).