Sodium hypochlorite is a colorless or slightly yellow watery liquid with an odor of household bleach. Mixes with water.
Sodium Hypochlorite is a greenish-yellow liquid commonly referred to as “Bleach”. The chemical compound formula for Sodium Hypochlorite is NaOCl. Sodium Hypochlorite is prepared by reacting dilute caustic soda solution with liquid or gaseous chlorine, accompanied by cooling.
Chlorine bleach, sodium hypochlorite (NaOCl), is a very useful and inexpensive disinfectant. A disinfectant kills germs that can make people sick. Sodium hypochlorite is just one of the common chlorine disinfectants; chlorine gas (Cl2) and solid calcium hypochlorite [Ca(OCl)2] are two others.
By adding hypochlorite to water, hypochlorous acid (HOCl) is formed:
NaOCl + H2O → HOCl + NaOH–
Hypochlorous acid is divided into hydrochloric acid (HCl) and oxygen (O). The oxygen atom is a very strong oxidator.
Sodium hypochlorite is effective against bacteria, viruses and fungi. Sodium hypochlorite disinfects the same way as chlorine does.
Applications of Sodium Hypochlorite
Sodium hypochlorite is used on a large scale. For example in agriculture, chemical industries, paint- and lime industries, food industries, glass industries, paper industries, pharmaceutical industries, synthetics industries and waste disposal industries. In the textile industry sodium hypochlorite is used to bleach textile. It is sometimes added to industrial waste water. This is done to reduce odors. Hypochlorite neutralizes sulphur hydrogen gas (SH) and ammonia (NH3). It is also used to detoxify cyanide baths in metal industries. Hypochlorite can be used to prevent algae and shellfish growth in cooling towers. In water treatment, hypochlorite is used to disinfect water. In households, hypochlorite is used frequently for the purification and disinfection of the house.
Sodium Hypochlorite is the main ingredient in laundry bleach. It is used extensively as a bleaching agent in the textile, detergents, and paper and pulp industries. It is also used as an oxidizing agent for organic products. In the petrochemical industry, sodium hypochlorite is used in petroleum products refining. Large quantities are also used as a disinfectant in water and wastewater treatment and sanitary equipment. In food processing, sodium hypochlorite is used to sanitize food preparation equipment, in fruit and vegetable processing, mushroom production, hog, beef and poultry production, maple syrup production, and fish processing.
odium hypochlorite is applied in swimming pools for water disinfection and oxidation. It has the advantage that microorganisms cannot build up any resistance to it. Sodium hypochlorite is effective against Legionella bacteria and bio film, in which Legionella bacteria can multiply.
Hypochlorous acid is produced by the reaction of sodium hydroxide with chlorine gas. In water, the so-called ‘active chlorine’ is formed.
There are various ways to use sodium hypochlorite. For on-site salt electrolysis, a solution of salt (NaCl) in water is applied. Sodium (Na+) and chloride (Cl–) ions are produced.
4NaCl– → 4Na+ + 4Cl–
By leading the salty solution over an electrolysis cell, the following reactions take place at the electrodes:
2Cl- → Cl2 + 2e- 2H2O + 2e- → H2 + 20H–
2H20 → O2 + 4H++ 4e-
In various parts of the world, sodium hypochlorite strength is identified using five common definitions that result in different numbers although the oxidizing power is the same, i.e., the sodium hypochlorite strength is the same.