A water softener reduces the dissolved calcium, magnesium, and to some degree manganese and ferrous iron ion concentration in hard water. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 Manganese (ˈmæŋgəniːz is a Chemical element, designated by the symbol Mn. Iron(II oxide, also known as ferrous oxide, iron oxide/oxidized iron or more commonly rusted Hard water is the type of Water that has high Mineral content (in contrast with Soft water)
These "hardness ions" cause three major kinds of undesired effects. Most visibly, metal ions react with soaps and calcium-sensitive detergents, hindering their ability to lather and forming a precipitate—the familiar "bathtub ring". SOAP (see below for name and origins is a protocol for exchanging XML -based messages over Computer networks normally using A detergent (as a noun is a material intended to assist Cleaning. Precipitation is the formation of a Solid in a Solution during a Chemical reaction. Presence of "hardness ions" also inhibits the cleaning effect of detergent formulations. Secondly, calcium and magnesium carbonates tend to adhere to the surfaces of pipes and heat exchanger surfaces. The resulting build-up of scale can restrict water flow in pipes. In boilers, the deposits act as an insulation that impairs the flow of heat into water, reducing the heating efficiency and allowing the metal boiler components to overheat. In a pressurized system, this can lead to failure of the boiler. [1] Thirdly, the presence of ions in an electrolyte, in this case, hard water, can also lead to galvanic corrosion, in which one metal will preferentially corrode when in contact with another type of metal, when both are in contact with an electrolyte. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium Galvanic corrosion is an Electrochemical process in which one Metal Corrodes preferentially when in electrical contact with a different type of metal Corrosion means the breaking down of essential properties in a material due to Chemical reactions with its surroundings
Conventional water-softening devices intended for household use depend on an ion-exchange resin in which "hardness" ions trade places with sodium ions that are electrostatically bound to the anionic functional groups of the polymeric resin. ion-exchange resin is an insoluble matrix (or support structure normally in the form of small (1-2 mm diameter beads usually white or yellowish fabricated from an organic Polymer An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge A class of minerals called zeolites also exhibits ion-exchange properties; these minerals were widely used in earlier water softeners. Zeolites (Greek zein, "to boil" lithos, "a stone" are hydrated Aluminosilicate Minerals and have a micro-porous structure Water softeners are typically required when the source of water is a well, whether municipal or private.
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Chelating agents
Chelators are used in chemical analysis, as water softeners, and are ingredients in many commercial products such as shampoos and food preservatives. Chelation is the binding or complexation of a bi- or multidentate Ligand. Analytical chemistry is the study of the Chemical composition of natural and artificial Materials. Shampoo is a Hair care product used for the removal of oils, dirt skin particles Dandruff, environmental pollutants and other contaminant particles that A preservative is a natural or synthetic chemical that is added to products such as foods pharmaceuticals paints biological samples wood etc Citric acid is used to soften water in soaps and laundry detergents. Citric acid is a weak organic Acid. It is a natural Preservative and is also used to add an acidic or sour taste to foods and Soft drinks Citric acid is a weak organic Acid. It is a natural Preservative and is also used to add an acidic or sour taste to foods and Soft drinks Laundry detergent, or washing powder, is a substance which is a type of Detergent that is added when one is washing Laundry to help get the laundry cleaner A commonly used synthetic chelator is EDTA. EDTA is a widely used abbreviation for the Chemical compound ethylenediaminetetraacetic acid (and many other names see table
Ion-exchange resin devices
How it works
The water to be treated passes through a bed of the resin. Negatively-charged resins absorb and bind metal ions, which are positively charged. The resins initially contain univalent hydrogen, sodium or potassium ions, which exchange with divalent calcium and magnesium ions in the water. In Chemistry, valence, also known as valency or valency number, is a measure of the number of Chemical bonds formed by the Atoms Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 Potassium (pəˈtæsiəm is a Chemical element. It has the symbol K (kalium from qalīy Atomic number 19 and Atomic mass 39 In chemistry divalent Anions are atoms or radicals with 2 additional Electrons when compared to their elemental state (that is with 2 more electrons than Protons This exchange eliminates precipitation and soap scum formation. As the water passes through both kinds of resin, the hardness ions replace the hydrogen, sodium or potassium ions which are released into the water. The "harder" the water, the more hydrogen, sodium or potassium ions are released from the resin and into the water.
Regeneration
As these resins become loaded with hardness ions they gradually lose their effectiveness and must be regenerated by passing a concentrated brine, usually of sodium chloride or potassium chloride, or hydrochloric acid solution through them. For sodium chloride in the diet see Salt. Sodium chloride, also known as common salt, table salt, or Halite, is a The Chemical compound potassium chloride (KCl is a Metal Halide salt composed of Potassium and Chlorine. Most of the salts used for regeneration gets flushed out of the system and may be released into the soil or sewer. These processes can be damaging to the environment, especially in arid regions. Some jurisdictions prohibit such release and require users to dispose of the spent brine at an approved site or to use a commercial service company. Most water softener manufacturers provide metered control valves to minimize the frequency of regeneration. It is also possible on most units to adjust the amount of salt used for each regeneration. Both of these steps are recommended to minimize the impact of water softeners on the environment and conserve on salt use. Using acid to regenerate lowers the pH of the regeneration waste.
In industrial scale water softening plants, the effluent flow from re-generation process can be very significant. Under certain conditions, such as when the effluent is discharged in admixture with domestic sewage, the calcium and magnesium salts may precipitate out as hardness scale on the inside of the discharge pipe. This can build up to such an extent so as to block the pipe as happened to a major chlor-alkali plant on the south Wales coast in the 1980s.
Effects of sodium
For people on a low-sodium diet, the increase in sodium levels (for systems releasing sodium) in the water can be significant, especially when treating very hard water. A paper by Kansas State University gives an example: "A person who drinks two liters (2L) of softened, extremely hard water (assume 30 gpg) will consume about 480 mg more sodium (2L x 30 gpg x 8 mg/L/gpg = 480 mg), than if unsoftened water is consumed. Kansas State University, commonly shortened to K-State, is an institution of higher learning located in Manhattan, Kansas, in the United States " This is a significant amount, as they state: "The American Heart Association (AHA) suggests that the 3 percent of the population who must follow a severe, salt-restricted diet should not consume more than 400 mg of sodium a day. AHA suggests that no more than 10 percent of this sodium intake should come from water. The EPA’s draft guideline of 20 mg/L for water protects people who are most susceptible. "[2] Most people who are concerned with the added sodium in the water generally have one faucet in the house that bypasses the softener, or have a reverse osmosis unit installed for the drinking water and cooking water, which was designed for desalinisation of sea water. Reverse osmosis (RO is a separation process that uses pressure to force a Solution through a membrane that retains the Solute on one side and allows the Desalination, desalinization, or desalinisation refers to any of several processes that remove excess salt and other Minerals from Water Seawater is Water from a Sea or Ocean. On average seawater in the world's oceans has a Salinity of about 3
See also
References
- ^ Stephen Lower (July 2007). Ion exchange is an exchange of Ions between two Electrolytes or between an electrolyte Solution and a complex. Water purification is the process of removing contaminants and other harmful microorganisms from a raw water source A descaling agent, also known as descaling, anti-limestone, anti-limescale, anti-lime, or anti-scale, is a Solution to Desalination, desalinization, or desalinisation refers to any of several processes that remove excess salt and other Minerals from Water Hard water and water softening. Retrieved on 2007-10-08. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 314 - Roman Emperor Licinius is defeated by his colleague Constantine I at the Battle of Cibalae, and loses
- ^ Michael H. Bradshaw, G. Morgan Powell (October 2002). Sodium in Drinking Water. Kansas State University. Kansas State University, commonly shortened to K-State, is an institution of higher learning located in Manhattan, Kansas, in the United States Retrieved on 2007-04-03. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1043 - Edward the Confessor is crowned King of England.
External links
- Wilkes University hard water site
- Riverside County CA water softener restrictions
- Water softener diagram
- Water softener regeneration
- Gallery of water-related pseudoscience - Chemist's site providing explanations of how alternatives to water softening, such as catalytic water conditioning, are not scientifically grounded
Dictionary
water softening
-noun
- The removal of calcium and magnesium ions from water, or their replacement with sodium, either by chemical reaction or by ion exchange.
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