Sodium hypochlorite (NaOCl) is a compound that can be effectively used for water disinfection. It is used on a large scale for bleaching, odor removal and water disinfection.
When was sodium hypochlorite discovered?
Sodium hypochlorite has a long history. Around 1785 the Frenchman Berthollet developed liquid bleaching agents based on sodium hypochlorite. The Javel company introduced this product and called it 'liqueur de Javel'. At first, it was used to bleach cotton. Because of its specific characteristics it soon became a popular compound. Hypochlorite can remove stains from clothes at room temperature. In France, sodium hypochlorite is still known as 'eau de Javel'.
What are the characteristics of sodium hypochlorite?
Sodium hypochlorite is a clear, slightly yellowish solution with a characteristic odor. Sodium hypochlorite has a relative density of is 1,1 (5,5% watery solution). As a bleaching agent for domestic use it usually contains 5% sodium hypochlorite (with a pH of around 11, it is irritating). If it is more concentrated, it contains a concentration 10-15% sodium hypochlorite (with a pH of around 13, it burns and is corrosive). Sodium hypochlorite is unstable. Chlorine evaporates at a rate of 0,75 gram active chlorine per day from the solution. Then heated sodium hypochlorite disintegrates. This also happens when sodium hypochlorite comes in contact with acids, sunlight, certain metals and poisonous and corrosive gasses, including chlorine gas. Sodium hypochlorite is a strong oxidator and reacts with flammable compounds and reductors. Sodium hypochlorite solution is a weak base that is inflammable. These characteristics must be kept in mind during transport, storage and use of sodium hypochlorite.
What do I need in order to make hypochlorite?
Salt is the basic ingredient required to make hypochlorite, so we can use brine or sea water as raw material. The brine should be dilute into 3%, the oceans vary from around 2% to slightly more than 4% with 3.5% being the average.
What are the applications of sodium hypochlorite?
Sodium hypochlorite is used on a large scale. For example in water and waste water plant, power plant, oil industry, agriculture, chemical industries, paint- and lime industries, food industries, glass industries, paper industries, pharmaceutical industries and synthetics 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 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.
What are the advantages and disadvantages of sodium hypochlorite use?
Sodium hypochlorite as a disinfectant has the following advantages:
It can easily and be stored and transported when it is produced on-site. Dosage is simple. Transport and storage of sodium hypochlorite are safe. Sodium hypochlorite is as effective as chlorine gas for disinfection. Sodium hypochlorite produces residual disinfectant.
Sodium hypochlorite should not come in contact with air, because that will cause it to disintegrate. Both sodium hypochlorite and chlorine do not deactivate Giardia Lambia and Cryptosporidium.
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