Chlorine is a chemical element; it has symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity on the revised Pauling scale, behind only oxygen and fluorine.
Sodium hypochlorite, commonly known in a dilute solution as (chlorine) bleach, is an alkaline inorganic chemical compound with the formula NaOCl, consisting of a sodium cation and a hypochlorite anion. It may also be viewed as the sodium salt of hypochlorous acid. The anhydrous compound is unstable and may decompose explosively. It can be crystallized as a pentahydrate NaOCl·5H
2O, a pale greenish-yellow solid which is not explosive and is stable if kept refrigerated.
Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for human consumption, but water purification may also be carried out for a variety of other purposes, including medical, pharmacological, chemical, and industrial applications. The history of water purification includes a wide variety of methods. The methods used include physical processes such as filtration, sedimentation, and distillation; biological processes such as slow sand filters or biologically active carbon; chemical processes such as flocculation and chlorination; and the use of electromagnetic radiation such as ultraviolet light.
Hypochlorous acid is an inorganic compound with the chemical formula ClOH, also written as HClO, HOCl, or ClHO. Its structure is H−O−Cl. It is an acid that forms when chlorine dissolves in water, and itself partially dissociates, forming hypochlorite anion, ClO−. HClO and ClO− are oxidizers, and the primary disinfection agents of chlorine solutions. HClO cannot be isolated from these solutions due to rapid equilibration with its precursor, chlorine.
In chemistry, hypochlorite, or chloroxide is an anion with the chemical formula ClO−. It combines with a number of cations to form hypochlorite salts. Common examples include sodium hypochlorite and calcium hypochlorite. The Cl-O distance in ClO− is 1.69 Å.
Nitrogen trichloride, also known as trichloramine, is the chemical compound with the formula NCl3. This yellow, oily, pungent-smelling and explosive liquid is most commonly encountered as a byproduct of chemical reactions between ammonia-derivatives and chlorine. Alongside monochloramine and dichloramine, trichloramine is responsible for the distinctive 'chlorine smell' associated with swimming pools, where the compound is readily formed as a product from hypochlorous acid reacting with ammonia and other nitrogenous substances in the water, such as urea from urine.
Calcium hypochlorite is an inorganic compound with formula Ca(ClO)2. It is a white solid, although commercial samples appear yellow. It strongly smells of chlorine, owing to its slow decomposition in moist air. This compound is relatively stable as a solid and solution and has greater available chlorine than sodium hypochlorite. "Pure" samples have 99.2% active chlorine. Given common industrial purity, an active chlorine content of 65-70% is typical. It is the main active ingredient of commercial products called bleaching powder, used for water treatment and as a bleaching agent.
Salt water chlorination is a process that uses dissolved salt for the chlorination of swimming pools and hot tubs. The chlorine generator uses electrolysis in the presence of dissolved salt to produce chlorine gas or its dissolved forms, hypochlorous acid and sodium hypochlorite, which are already commonly used as sanitizing agents in pools. Hydrogen is produced as byproduct too.
Monochloramine, often called chloramine, is the chemical compound with the formula NH2Cl. Together with dichloramine (NHCl2) and nitrogen trichloride (NCl3), it is one of the three chloramines of ammonia. It is a colorless liquid at its melting point of −66 °C (−87 °F), but it is usually handled as a dilute aqueous solution, in which form it is sometimes used as a disinfectant. Chloramine is too unstable to have its boiling point measured.
Chloramines refer to derivatives of ammonia and organic amines wherein one or more N−H bonds have been replaced by N−Cl bonds. Two classes of compounds are considered: inorganic chloramines and organic chloramines. Chloramines are the most widely used members of the halamines.
Dichloramine is a reactive inorganic compound with the chemical formula NHCl2. It is one of the three chloramines of ammonia, the others being monochloramine and nitrogen trichloride. This yellow gas is unstable and reacts with many materials. It is formed by a reaction between ammonia and chlorine or sodium hypochlorite. It is a byproduct formed during the synthesis of monochloramine and nitrogen trichloride.
Swimming pool sanitation is the process of ensuring healthy conditions in swimming pools. Proper sanitation is needed to maintain the visual clarity of water and to prevent the transmission of infectious waterborne diseases.
Bleach is the generic name for any chemical product that is used industrially or domestically to remove colour (whitening) from fabric or fiber or to disinfect after cleaning. It often refers specifically to a dilute solution of sodium hypochlorite, also called "liquid bleach".
Disinfection by-products (DBPs) are organic and inorganic compounds resulting from chemical reactions between organic and inorganic substances such as contaminates and chemical treatment disinfection agents, respectively, in water during water disinfection processes.
A swimming pool, swimming bath, wading pool, paddling pool, or simply pool, is a structure designed to hold water to enable swimming or other leisure activities. Pools can be built into the ground or built above ground, and may be found as a feature aboard ocean-liners and cruise ships. In-ground pools are most commonly constructed from materials such as concrete, natural stone, metal, plastic, composite or fiberglass, and can be of a custom size and shape or built to a standardized size, the largest of which is the Olympic-size swimming pool.
Electrochlorination is the process of producing hypochlorite by passing electric current through salt water. This disinfects the water and makes it safe for human use, such as for drinking water or swimming pools.
Water chlorination is the process of adding chlorine or chlorine compounds such as sodium hypochlorite to water. This method is used to kill bacteria, viruses and other microbes in water. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, and typhoid.
Respiratory risks of indoor swimming pools can include coughing, wheezing, aggravated asthma, and airway hyper-responsiveness. The chemicals used for pool water disinfection can react with organic compounds in the water to create disinfection by-products or DBPs. Exposure to these DBPs are the potential cause for respiratory symptoms in swimmers. Multiple studies have shown the potential correlation between chronic exposure to DBPs and respiratory symptoms among competitive swimmers but more research is needed on the effects of these DBPs on recreational swimmers. The studies on recreational swimmers that have been done show a decreased risk for respiratory symptoms due to a decreased exposure to DBPs. Some studies have been done on the vulnerability of younger children and DBP exposure. Studies done on the vulnerability of younger children demonstrate that immature lungs are more likely to absorb more of these DBPs.
Chlorine-releasing compounds, also known as chlorine base compounds, is jargon to describe certain chlorine-containing substances that are used as disinfectants and bleaches. They include the following chemicals: sodium hypochlorite, chloramine, halazone, and sodium dichloroisocyanurate. They are widely used to disinfect water and medical equipment, and surface areas as well as bleaching materials such as cloth. The presence of organic matter can make them less effective as disinfectants. They come as a liquid solution, or as a powder that is mixed with water before use.
A skimmer or surface separator is an essential accessory for the maintenance and cleaning of the water in a swimming pool. It is used to remove all the surface dirt floating on the water surface, such as leaves, tanning oil and human secretions. These impurities remain suspended on the surface, affect the appearance of the water and are not always removed by the conventional vacuuming process. The skimmer is installed directly in the surface water suction system and also has the function of controlling the water level to prevent accidental overflows. In the United States and Portugal, the use of skimmers in the construction of swimming pools is mandatory, regulated and standardized by competent bodies.
