Difference between revisions of "Diatomaceous earth" - New World Encyclopedia

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[[Image:Mineraly.sk - diatomit.jpg|right|thumb|250px|A sample of diatomaceous earth]]
 
[[Image:Mineraly.sk - diatomit.jpg|right|thumb|250px|A sample of diatomaceous earth]]
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'''Diatomaceous earth''' ([[International Phonetic Alphabet|IPA]]: {{IPA|/ˌdʌɪətəˈmeɪʃəs ˈəː(r)θ/}}, also known as '''DE''', '''diatomite''', '''diahydro''', '''kieselguhr''', '''kieselgur''' and '''Celite''') is a naturally occurring, soft, [[chalk]]-like sedimentary [[rock (geology)|rock]] that is easily crumbled into a fine white to off-white powder. This powder has an [[abrasive]] feel, similar to [[pumice]] powder, and is very light, due to its high [[porosity]]. The typical chemical composition of diatomaceous earth is 86% [[silica]], 5% [[sodium]], 3% [[magnesium]] and 2% [[iron]].
 
'''Diatomaceous earth''' ([[International Phonetic Alphabet|IPA]]: {{IPA|/ˌdʌɪətəˈmeɪʃəs ˈəː(r)θ/}}, also known as '''DE''', '''diatomite''', '''diahydro''', '''kieselguhr''', '''kieselgur''' and '''Celite''') is a naturally occurring, soft, [[chalk]]-like sedimentary [[rock (geology)|rock]] that is easily crumbled into a fine white to off-white powder. This powder has an [[abrasive]] feel, similar to [[pumice]] powder, and is very light, due to its high [[porosity]]. The typical chemical composition of diatomaceous earth is 86% [[silica]], 5% [[sodium]], 3% [[magnesium]] and 2% [[iron]].
  
 
Diatomaceous earth consists of fossilized remains of [[diatom]]s, a type of hard-shelled [[algae]]. It is used as a [[filtration]] aid, as a mild abrasive, as a mechanical [[insecticide]], as an [[absorbent]] for liquids, as [[cat litter]], as an activator in [[blood clotting]] studies, and as a component of [[dynamite]]. As it is also heat-resistant, it can be used as a [[thermal insulation|thermal insulator]].  
 
Diatomaceous earth consists of fossilized remains of [[diatom]]s, a type of hard-shelled [[algae]]. It is used as a [[filtration]] aid, as a mild abrasive, as a mechanical [[insecticide]], as an [[absorbent]] for liquids, as [[cat litter]], as an activator in [[blood clotting]] studies, and as a component of [[dynamite]]. As it is also heat-resistant, it can be used as a [[thermal insulation|thermal insulator]].  
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== Characteristics ==
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<<Section needs more details>>
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Because diatomite forms from the remains of water-borne [[diatom]]s, it is found close to either current or former bodies of water. It is generally divided into two categories based upon source: [[freshwater]] and [[Seawater|saltwater]]. Freshwater diatomite is mined from dry lakebeds and is characteristically low in [[crystal]]line silica content. Saltwater diatomite contains a high crystalline silica content, making it a useful material for filters, due to the sieve-like features of the crystals.
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== Specific varieties ==
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*'''TripoliteDakine''' is the variety found in [[Tripoli]], [[Libya]].
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*'''Bann clay''' is the variety found in the [[River Bann|Lower Bann valley]] in [[Northern Ireland]].
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*'''Moler''' ('''Mo-clay''') is the variety found in northwestern [[Denmark]], especially on the islands of [[Fur (island)|Fur]] and [[Mors (island)|Mors]].
  
 
== Applications ==
 
== Applications ==
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===Pest control===
 
===Pest control===
Diatomite is also used as an [[insecticide]], due to its physico-[[sorptivity|sorptive]] properties. The fine powder absorbs lipids from the [[Exoskeleton|cuticle]], the waxy outer layer of insects' [[exoskeleton]]s, causing them to dehydrate. [[Arthropod]]s die as a result of the water pressure deficiency, based on [[Fick's law of diffusion]]. This also works against [[gastropod]]s and is commonly employed in gardening to defeat [[slug]]s. However, since slugs inhabit humid environments, efficacy is very low. [[Beekeeping|Beekeepers]] are apparently experimenting with it, to keep [[small hive beetle]]s from breeding. It is sometimes mixed with an attractant or other additives to increase its effectiveness. Medical grade diatomite is sometimes used to de-worm both animals and humans. It is most commonly used in lieu of [[boric acid]], and can be used to help control and eventually eliminate a [[cockroach]] infestation.
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Diatomite is also used as an [[insecticide]], due to its physico-[[sorptivity|sorptive]] properties. The fine powder absorbs lipids from the [[Exoskeleton|cuticle]], the waxy outer layer of insects' exoskeletons, causing them to dehydrate. [[Arthropod]]s die as a result of the water pressure deficiency, based on [[Fick's law of diffusion]]. This also works against [[gastropod]]s and is commonly employed in gardening to defeat [[slug]]s. However, since slugs inhabit humid environments, efficacy is very low. [[Beekeeping|Beekeepers]] are apparently experimenting with it, to keep [[small hive beetle]]s from breeding. It is sometimes mixed with an attractant or other additives to increase its effectiveness. Medical grade diatomite is sometimes used to de-worm both animals and humans. It is most commonly used in lieu of [[boric acid]], and can be used to help control and eventually eliminate a [[cockroach]] infestation.
  
 
=== Absorbent ===
 
=== Absorbent ===
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More recently, it has been employed as a primary ingredient in a type of cat litter. The type of silica used in cat litter comes from freshwater sources and does not pose a significant health risk to pets or humans.
 
More recently, it has been employed as a primary ingredient in a type of cat litter. The type of silica used in cat litter comes from freshwater sources and does not pose a significant health risk to pets or humans.
  
In [[1867]], [[Alfred Nobel]] discovered that [[nitroglycerin]] could be made much more stable if absorbed in diatomite. He patented this mixture as [[dynamite]], and the mixture is also referred to as guhr dynamite.
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In 1867, [[Alfred Nobel]] discovered that [[nitroglycerin]] could be made much more stable if absorbed in diatomite. He patented this mixture as [[dynamite]], and the mixture is also referred to as guhr dynamite.
  
 
=== Thermal ===
 
=== Thermal ===
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Freshwater diatomite can be used as a growing medium in [[hydroponic]] gardens.
 
Freshwater diatomite can be used as a growing medium in [[hydroponic]] gardens.
 
== Geology ==
 
 
{{Expand|date=January 2007}}
 
 
Because diatomite forms from the remains of water-borne [[diatom]]s, it is found close to either current or former bodies of water. It is generally divided into two categories based upon source: [[freshwater]] and [[Seawater|saltwater]]. Freshwater diatomite is mined from dry lakebeds and is characteristically low in [[crystal]]line silica content. Saltwater diatomite contains a high crystalline silica content, making it a useful material for filters, due to the sieve-like features of the crystals.
 
 
== Specific varieties ==
 
 
*'''TripoliteDakine''' is the variety found in [[Tripoli]], [[Libya]].
 
*'''Bann clay''' is the variety found in the [[River Bann|Lower Bann valley]] in [[Northern Ireland]].
 
*'''Moler''' ('''Mo-clay''') is the variety found in northwestern [[Denmark]], especially on the islands of [[Fur (island)|Fur]] and [[Mors (island)|Mors]].
 
  
 
== Climatologic importance ==
 
== Climatologic importance ==
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The type of hazard posed by inhalation depends on the form of the silica. Crystalline silica poses a serious inhalation hazard because it can cause [[silicosis]]. Amorphous silica can cause dusty lungs, but does not carry the same degree of risk as crystalline silica. Food-grade diatomite generally contains very low percentages of crystalline silica. Diatomite produced for pool filters is treated with heat, causing the formerly amorphous silicon dioxide to assume its crystalline form.
 
The type of hazard posed by inhalation depends on the form of the silica. Crystalline silica poses a serious inhalation hazard because it can cause [[silicosis]]. Amorphous silica can cause dusty lungs, but does not carry the same degree of risk as crystalline silica. Food-grade diatomite generally contains very low percentages of crystalline silica. Diatomite produced for pool filters is treated with heat, causing the formerly amorphous silicon dioxide to assume its crystalline form.
  
In the [[United States]], the crystalline silica content in the dusts is regulated by the Occupational Safety and Health Administration (OSHA), and there are guidelines for the maximum amounts allowable in the product and in the air near the breathing zone of workers. <ref>[http://www.oznet.ksu.edu/grsc_subi/Teaching/GRSC651/GRSC651_Courses_Material/lecture_slides/GRSC651_lect_20(1)_Inert_Dusts.pdf Inert Dusts] at [[Kansas State University]]</ref>
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In the [[United States]], the crystalline silica content in the dusts is regulated by the Occupational Safety and Health Administration (OSHA), and there are guidelines for the maximum amounts allowable in the product and in the air near the breathing zone of workers. <ref>[http://www.oznet.ksu.edu/grsc_subi/Teaching/GRSC651/GRSC651_Courses_Material/lecture_slides/GRSC651_lect_20(1)_Inert_Dusts.pdf Inert Dusts] at [[Kansas State University]].</ref>
  
 
== See also ==
 
== See also ==
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* [[Biomineralization]]
 
* [[Biomineralization]]
 
* [[Diatom]]
 
* [[Diatom]]
 
* [[Fuller's Earth]]
 
* [[Fuller's Earth]]
 
* [[Perlite]]
 
* [[Perlite]]
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== Notes ==
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<references/>
  
 
==References==
 
==References==
<references/>
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* [http://minerals.usgs.gov/minerals/pubs/commodity/diatomite/ Minerals Information: Diatomite.] ''U.S. Geological Survey''. Retrieved May 14, 2007.
  
 
== External links ==
 
== External links ==
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* [http://www.ppearth.com/ Diatomaceous Earth in India]
 
* [http://www.ppearth.com/ Diatomaceous Earth in India]
 
* [http://minerals.usgs.gov/minerals/pubs/commodity/diatomite/ Diatomite: Statistics and Information - USGS]
 
* [http://minerals.usgs.gov/minerals/pubs/commodity/diatomite/ Diatomite: Statistics and Information - USGS]
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* [http://www.poultryyouth.com/articles/article-21/ Raising Poultry using Diatomacious Earth] - Article by the Poultry Youth Association
 
* [http://www.poultryyouth.com/articles/article-21/ Raising Poultry using Diatomacious Earth] - Article by the Poultry Youth Association
  
[[Category:Sedimentary rocks]]
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[[Category:Physical sciences]]
[[Category:Inorganic insecticides]]
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[[Category:Earth sciences]]
[[Category:Fossils]]
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[[Category:Geology]]
  
[[cs:Křemelina]]
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{{credit|130062476}}
[[da:Moler]]
 
[[de:Kieselgur]]
 
[[et:Diatomiit]]
 
[[fr:Kieselguhr]]
 
[[ja:珪藻土]]
 
[[ko:규조토]]
 
[[nl:Kiezelgoer]]
 
[[pl:Ziemia okrzemkowa]]
 
[[pt:Diatomito]]
 
[[fi:Piimaa]]
 
[[ru:Диатомит]]
 
[[sv:Kiselgur]]
 
[[th:ดินเบา]]
 
[[zh:矽藻土]]
 

Revision as of 21:57, 14 May 2007

A sample of diatomaceous earth

Diatomaceous earth (IPA: /ˌdʌɪətəˈmeɪʃəs ˈəː(r)θ/, also known as DE, diatomite, diahydro, kieselguhr, kieselgur and Celite) is a naturally occurring, soft, chalk-like sedimentary rock that is easily crumbled into a fine white to off-white powder. This powder has an abrasive feel, similar to pumice powder, and is very light, due to its high porosity. The typical chemical composition of diatomaceous earth is 86% silica, 5% sodium, 3% magnesium and 2% iron.

Diatomaceous earth consists of fossilized remains of diatoms, a type of hard-shelled algae. It is used as a filtration aid, as a mild abrasive, as a mechanical insecticide, as an absorbent for liquids, as cat litter, as an activator in blood clotting studies, and as a component of dynamite. As it is also heat-resistant, it can be used as a thermal insulator.

Characteristics

<<Section needs more details>>

Because diatomite forms from the remains of water-borne diatoms, it is found close to either current or former bodies of water. It is generally divided into two categories based upon source: freshwater and saltwater. Freshwater diatomite is mined from dry lakebeds and is characteristically low in crystalline silica content. Saltwater diatomite contains a high crystalline silica content, making it a useful material for filters, due to the sieve-like features of the crystals.

Specific varieties

  • TripoliteDakine is the variety found in Tripoli, Libya.
  • Bann clay is the variety found in the Lower Bann valley in Northern Ireland.
  • Moler (Mo-clay) is the variety found in northwestern Denmark, especially on the islands of Fur and Mors.

Applications

Filtration

The most common use (68%) of diatomaceous earth is as a filter medium, especially for swimming pools. It has a high porosity, because it is composed of microscopically-small, coffin-like, hollow particles. It is used in chemistry, as a filtration aid, to filter very fine particles that would otherwise pass or clog filter paper. It is also used to filter water, particularly in the drinking water treatment process, and other liquids, such as beer. It can also filter syrups and sugar. Other industries such as paper, paints, ceramics, soap and detergents use it as a fulling material.

Abrasive

The oldest use of diatomite is as a very mild abrasive and, for this purpose, it has been used both in toothpaste and in metal polishes, as well as in some facial scrubs.

Pest control

Diatomite is also used as an insecticide, due to its physico-sorptive properties. The fine powder absorbs lipids from the cuticle, the waxy outer layer of insects' exoskeletons, causing them to dehydrate. Arthropods die as a result of the water pressure deficiency, based on Fick's law of diffusion. This also works against gastropods and is commonly employed in gardening to defeat slugs. However, since slugs inhabit humid environments, efficacy is very low. Beekeepers are apparently experimenting with it, to keep small hive beetles from breeding. It is sometimes mixed with an attractant or other additives to increase its effectiveness. Medical grade diatomite is sometimes used to de-worm both animals and humans. It is most commonly used in lieu of boric acid, and can be used to help control and eventually eliminate a cockroach infestation.

Absorbent

Its absorbent qualities make it useful for spill clean-up and the U.S. Center for Disease Control recommends it to clean up toxic liquid spills.

More recently, it has been employed as a primary ingredient in a type of cat litter. The type of silica used in cat litter comes from freshwater sources and does not pose a significant health risk to pets or humans.

In 1867, Alfred Nobel discovered that nitroglycerin could be made much more stable if absorbed in diatomite. He patented this mixture as dynamite, and the mixture is also referred to as guhr dynamite.

Thermal

Its thermal properties enable it to be used as the barrier material in some fire resistant safes.

Hydroponics

Freshwater diatomite can be used as a growing medium in hydroponic gardens.

Climatologic importance

The Earth's climate depends greatly on the amount of dust in the atmosphere, and hence, locating major sources of dust are of great interest for climatology. Recent research indicates that surface deposits of diatomaceous earth play a dominant resource here, a major example being the Bodélé depression in the part of the Sahara belonging to Chad, where storms push diatomite gravel over dunes, where dust is abraded, leading to the largest single influx of dust into the atmosphere. [1]

Safety considerations

The absorbent qualities of diatomite can result in a significant drying of the hands, if handled without gloves. The saltwater (industrial) form contains a highly crystalline form of silica, resulting in sharp edges. The sharpness of this version of the material makes it dangerous to breathe and a dust mask is recommended when working with it.

The type of hazard posed by inhalation depends on the form of the silica. Crystalline silica poses a serious inhalation hazard because it can cause silicosis. Amorphous silica can cause dusty lungs, but does not carry the same degree of risk as crystalline silica. Food-grade diatomite generally contains very low percentages of crystalline silica. Diatomite produced for pool filters is treated with heat, causing the formerly amorphous silicon dioxide to assume its crystalline form.

In the United States, the crystalline silica content in the dusts is regulated by the Occupational Safety and Health Administration (OSHA), and there are guidelines for the maximum amounts allowable in the product and in the air near the breathing zone of workers. [2]

See also

  • Biomineralization
  • Diatom
  • Fuller's Earth
  • Perlite

Notes

  1. Washington et al., Geophys. Res. Lett. 33 (2006) L09401 Digital object identifier (DOI): 10.1029/2006GL025827 .
  2. Inert Dusts at Kansas State University.

References
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External links

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