Sodium Hydroxide

Sodium hydroxide is also known as Lye, Caustic soda, Alkaline drain cleaner (in solution), Sodium hydrate, Ascarite.

The electrolysis of sodium chloride produces sodium hydroxide and chlorine together. In many parts of the world, there are large deposits of sodium chloride (rock salt). These deposits are nearly pure sodium chloride and are often several hundred meters deep (some up to 3000 meters deep) with 30 to 500 meter thick seams. During the Triassic period, 200 million years ago, they were evaporated from trapped seas. In Europe, for example, the seas produced deposits stretching from Cheshire, Lancashire, Staffordshire, and Cleveland in the UK to Poland, although not continuously. It is also found across the U.S., especially in Louisiana and Texas. A small quantity is mined as rock salt, most are mined by the controlled pumping of water into the salt seam at high pressure. In order to produce dry salt, a proportion of the solution mined brine produced in this way is evaporated. Solar salt is also a source of sodium chloride, produced by the evaporation of seawater by solar heating.

Saturated brine is purified before electrolysis by adding sodium carbonate, sodium hydroxide, and other reagents to precipitate calcium, magnesium and other harmful cations. Settling and filtration remove the suspended solids from the brine. Today, the three electrolytic processes used. The concentration of caustic soda produced by each process varies:

Sodium hydroxide is used in a wide variety of industries, including paper, inorganic chemicals, organic chemicals, aluminum, textiles. A lot is used to scrub gases to remove acids before they are released into the open environment. For example, gasses emitted from the combustion of fossil fuels containing significant amounts of sulfur dioxide. Sulfur dioxide is trapped in many ways, one that is widely used involves scrubbing the gasses with a solution of sodium and calcium hydroxides. This technique is also used in processes of refining, such as bauxite purification.
Another important use of sodium hydroxide is the production of wood paper. Wood is treated with a solution containing a mixture of sodium sulfide and sodium hydroxide in the most widely used process, the Kraft process. Most of the unwanted material in the wood, such as lignins, dissolves in the liquor, leaving cellulose that is filtered off relatively pure. It is this cellulose that forms the basis of paper after further purification. Other uses include the manufacturing of detergents, soaps, and bleaches, which are usually produced by transferring chlorine gas to a sodium hydroxide solution that generates a sodium chlorate (I) solution (sodium hypochlorite):
Cl₂ (g) + 2 NaOH (aq) NaCl (aq) + NaOCl (aq) + H₂O (l)

Ingestion: Corrosive. Swallowing can lead to severe mouth, throat, and stomach burns. It can result in severe tissue scarring and death. There may be similar symptoms of inhalation, severe pain, severe tissue scarring, diarrhea, bleeding, vomiting, blood pressure drop, collapse, and death. Damage can occur days after exposure. Risk of esophagus and stomach perforation.

Inhalation: Significant irritant. Effects from dust or nebula inhalation vary from mild irritation to severe damage or burning of upper respiratory tract mucous membranes, depending on the severity of exposure. Coughing, wheezing, laryngitis, shortness of breath, nausea, vomiting, sneezing, sore throat, or runny nose may include symptoms. There may be severe chemical pneumonitis and pulmonary edema.

Skin: Skin corrosive. Skin contact causes severe burns and scarring. Can thoroughly penetrate. Burns are not immediately painful, there may be minutes to hours of pain and irritation.

Eye: It's corrosive. Causes heavy burns. Can thoroughly penetrate. Ulceration, permanent vision impairment, and permanent blindness may occur in severe cases.

Ingestion: immediately rinse your mouth thoroughly with water. Give drinking water. DO NOT stir up vomiting. If vomiting occurs, to reduce the risk of aspiration, lean the victim forward. If vomiting occurs, provide additional water for effective dilution. Search for immediate medical help.
Skin: Wash immediately affected areas with abundant amounts of water. Remove and wash contaminated clothes prior to reuse. Search for urgent medical help. Use an emollient to cover the skin.

Eye Contact: Immediately irrigate for at least 15 minutes with copious amounts of water. Holding eyelids open. Search for immediate medical help. If available, an additional 30 minutes may be used with a neutral saline solution to flush the contaminated eye.

Avoid dust generation or accumulation. Before reuse, contaminated clothes should be removed and washed. It is recommended to apply skin-protective barrier cream. After working with the material, wash hands and face thoroughly. Use away from all sources of ignition in well-ventilated areas. Wear appropriate respiratory equipment in the event of insufficient ventilation. In small quantities, add caustic to water when diluting or preparing a solution to avoid boiling and splattering.

The environmental hazard of sodium hydroxide is caused by the ion of hydroxide (pH effect). A high water concentration will lead to toxic effects on aquatic organisms such as fish.

Sodium hydroxide is used in industrial and consumer products in large quantities. Because of the alkaline properties, high concentrations of sodium hydroxide are corrosive. Direct contact should be avoided with these products. However, when humans are in contact with the substance's non-corrosive and non-irritating concentrations, no effects are expected on human health. In the environment, the substance is neutralized and is therefore not persistent. It is also not accumulating in organisms. Before discharging to the environment, the waste water containing sodium hydroxide should be neutralized (pH control). This prevents effects on the aquatic environment (e.g. organisms that live in a river). By careful using and following the instructions provided, this hazardous substance can be safely used.