Phosphate: Difference between revisions - Wikipedia


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{{Short description|Anion, salt, functional group or ester derived from a phosphoric acid}}

{{About|the orthophosphate ion|the organophosphorus derivatives|Organophosphate|other phosphates|phosphoric acids and phosphates}}

{{Distinguish|phosphate soda|phosphonate|phosphorus}}

{{Chembox

| Watchedfields = changed

| verifiedrevid = 458267616

| ImageFile1 = Phosphat-Ion.svg

| ImageFile1_Ref = {{chemboximage|correct|??}}

| ImageSize1 = 140

| ImageName1 = Stereo skeletal formula of phosphate

| ImageFileL1 = Phosphate-3D-balls.png

| ImageFileL1_Ref = {{chemboximage|correct|??}}

| ImageNameL1 = Aromatic ball and stick model of phosphate

| ImageFileR1 = Phosphate-3D-vdW.png

| ImageFileR1_Ref = {{chemboximage|correct|??}}

| ImageNameR1 = Space-filling model of phosphate

| IUPACName = Phosphate<ref>{{cite web|title = Phosphates – PubChem Public Chemical Database|url = https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=1061&loc=ec_rcs|work = The PubChem Project|location = USA|publisher = National Center of Biotechnology Information}}</ref>

| OtherNames = Orthophosphate<br />Tetraoxophosphate(V)<br />Tetraoxidophosphate(V)

| Section1 = {{Chembox Identifiers

| CASNo = 14265-44-2

| CASNo_Ref = {{cascite|correct|CAS}}

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| UNII = NK08V8K8HR

| SMILES = [O-]P([O-])([O-])=O

| SMILES_Comment = hypervalent form

| SMILES1 = [O-]P(=O)([O-])[O-]

| SMILES2SMILES1 = [O=-][P+]([O-])([O-])[O-]

| SMILES1_Comment = ionic form

| SMILES3 = [O-] [P+]([O-])([O-])[O-]

| StdInChI = 1S/H3O4P/c1-5(2,3)4/h(H3,1,2,3,4)/p-3

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

}}

| Section2 = {{Chembox Properties

| Formula = {{chem|PO|4|3−}}

| ConjugateAcid = [[Monohydrogen phosphate]]

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}}

In [[chemistry]], a '''phosphate''' is an [[anion]], [[salt (chemistry)|salt]], [[functional group]] or [[ester]] derived from a [[phosphoric acids and phosphates|phosphoric acid]]. It most commonly means '''orthophosphate''', a [[derivative]] of orthophosphoric acid, ''{{aka.''}} [[phosphoric acid]] {{chem2|H3PO4}}.

The '''phosphate''' or '''orthophosphate''' ion {{chem|[PO|4|]|3−}} is derived from phosphoric acid by the removal of three [[proton]]s {{chem|H|+}}. Removal of one proton gives the '''dihydrogen phosphate''' ion {{chem|[H|2|PO|4|]|−}} while removal of two ionsprotons gives the '''hydrogen phosphate''' ion {{chem|[HPO|4|]|2−}}. These names are also used for salts of those anions, such as [[ammonium dihydrogen phosphate]] and [[trisodium phosphate]].

<gallery heights="80110" mode="packed">

File:3-phosphoric-acid-3D-balls.png|{{chem|H|3|PO|4}}<br />[[Phosphoric acid|Phosphoric<br />acid]]

File:2-dihydrogenphosphate-3D-balls.png|{{chem|[H|2|PO|4|]|-}}<br />[[Dihydrogen phosphate|Dihydrogen<br />phosphate]]

File:1-hydrogenphosphate-3D-balls.png|{{chem|[HPO|4|]|2−}}<br />[[Monohydrogen phosphate|Hydrogen<br />phosphate]]

File:0-phosphate-3D-balls.png|{{chem|[PO|4|]|3−}}<br />'''Phosphate''' or '''orthophosphate'''

</gallery>

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Orthophosphates are especially important among the various [[phosphoric acids and phosphates|phosphates]] because of their key roles in [[biochemistry]], [[biogeochemistry]], and [[ecology]], and their economic importance for [[agriculture]] and industry.<ref name=PhosphatePrimer>{{cite web |url=http://www.fipr.state.fl.us/about-us/phosphate-primer/ |title=Phosphate Primer |url-status=live |archive-url=https://web.archive.org/web/20170829055956/http://www.fipr.state.fl.us/about-us/phosphate-primer/ |archive-date=29 August 2017 |website=Florida Industrial and Phosphate Research Institute |publisher=Florida Polytechnic University |access-date=30 March 2018 }}</ref> The addition and removal of phosphate groups ([[phosphorylation]] and [[dephosphorylation]]) are key steps in [[cell (biology)|cell]] [[metabolism]].

[[Orthophosphate|Orthophosphates]] can [[Condensation reaction|condense]] to form [[pyrophosphate]]s.

==Chemical properties==

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! p''K''<sub>''a''</sub>

|-

| {{chem2|H<sub>3</sub>PO<sub>4</sub> {{eqm}}<-> {{chem|H|2|PO|4|−}}H2PO4- + {{chem|H|+}}

| ''K''<sub>''a''1</submath chem>K_{a1} = \frac{[ \ce{{chem|H|+}} ] [ \ce{{chem|H|2|PO|4|−H2PO4-}]} ] / {[ \ce{{chem|H|3|PO|4H3PO4}]} ] ≈\approx 7.5 ×\times 10<sup>−3^{-3}</supmath>

| p''K''<sub>a1</sub> &nbsp;= &nbsp;2.14

|-

| {{chemchem2|H|2|PO|4|−}}H2PO4- {{eqm}}<-> {{chem|HPO|4|2−}}HPO4(2-) + {{chem|H|+}}

| ''K''<sub>''a''2</submath chem>K_{a2} = \frac{[ \ce{{chem|H|+}} ] [ \ce{{chem|H|PO|4|2−HPO4^2-}]} ] / {[ \ce{{chem|H|2|PO|4|−H2PO4-}]} ] ≈\approx 6.2 ×\times 10<sup>−8^{-8}</supmath>

| p''K''<sub>a2</sub> &nbsp;= &nbsp;7.20

|-

| {{chemchem2|HPO|4|2−}}HPO4(2-) {{eqm}}<-> {{chem|PO|4|3−}}PO4(3-) + {{chem|H|+}}

| ''K''<sub>''a''3</submath chem>K_{a3} = \frac{[ \ce{{chem|H|+}} ] [ \ce{{chem|PO|4|3−PO4^3-}]} ] / {[ \ce{{chem|H|PO|4|2−HPO4^2-}]} ] ≈\approx 2.14 ×\times 10<sup>−13^{-13}</supmath>

| p''K''<sub>a3</sub> &nbsp;= &nbsp;12.37

|}

Values are at 25{{nbsp}}°C and 0 ionic strength.

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In [[biological system]]s, phosphorus can be found as free phosphate anions in solution ('''inorganic phosphate''') or bound to organic molecules as various [[organophosphate]]s.

Inorganic phosphate is generally denoted '''P<sub>i</sub>''' and at physiological ([[Homeostasis|homeostatic]]) [[pH]] primarily consists of a mixture of {{chem|[HPO|4|]|2−}} and {{chem|[H|2|PO|4|]|−}} ions. At a neutral pH, as in the [[cytosol]] (pH = 7.0), the concentrations of the orthophoshoric acid and its three anions have the ratios

<math chem display=block>\begin{align}

: [ {{chem|H|2|PO|4|−}} ] / [ {{chem|H|3|PO|4}} ] ≈ 7.5 × 10<sup>4</sup>

\frac{[\ce{H2PO4-}]}{[\ce{H3PO4}]} &\approx 7.5 \times 10^4 \\[4pt]

: [ {{chem|H|PO|4|2−}} ] / [ {{chem|H|2|PO|4|−}} ] ≈ 0.62

\frac{[\ce{HPO4^2-}]}{[\ce{H2PO4-}]} &\approx 0.62 \\[4pt]

: [ {{chem|PO|4|3−}} ] / [ {{chem|H|PO|4|2−}} ] ≈ 2.14 × 10<sup>−6</sup>

\frac{[\ce{PO4^3-}]}{[\ce{HPO4^2-}]} &\approx 2.14 \times 10^{-6}

\end{align}</math>

Thus, only {{chem|[H|2|PO|4|]|−}} and {{chem|[HPO|4|]|2−}} ions are present in significant amounts in the cytosol (62% {{chem|[H|2|PO|4|]|−}}, 38% {{chem|[HPO|4|]|2−}}). In extracellular fluid (pH = 7.4), this proportion is inverted (61% {{chem|[HPO|4|]|2−}}, 39% {{chem|[H|2|PO|4|]|−}}).

Inorganic phosphate can also be present also as of [[pyrophosphate]] anions {{chem|[P|2|O|7|]|4-}}, which can give orthophosphate by [[hydrolysis]]:

:{{chem|[P|2|O|7|]|4-}} + H<sub>2</sub>O {{eqm}} 2 {{chem|[HPO|4|]|2−}}

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== Adverse health effects ==

{{More citations needed|date=July 2022}}

[[Hyperphosphatemia]], or a high blood level of phosphates, is associated with elevated [[Mortality rate|mortality]] in the general population. The most common cause of hyperphosphatemia in people, dogs, and cats is kidney failure. In cases of hyperphosphatemia, limittinglimiting consumption of phosphate-rich foods, such as some meats and dairy items and foods with a high phosphate-to-protein ratio, such as soft drinks, fast food, processed foods, condiments, and other products containing phosphate-salt additives is advised.<ref>Renal Dietitian Team, ''[https://www.ouh.nhs.uk/patient-guide/leaflets/files/56112Pphosphate.pdf Reducing phosphate in your diet]'', Oxford University Hospitals NHS Foundation Trust, 2022 review </ref>

Phosphates induce vascular [[calcification]], and a high concentration of phosphates in blood was found to be a predictor of [[Cardiovascular disease|cardiovascular events]].<ref name=":1">{{Cite journal|last1=Ritz|first1=Eberhard|last2=Hahn|first2=Kai|last3=Ketteler|first3=Markus|last4=Kuhlmann|first4=Martin K.|last5=Mann|first5=Johannes|date=January 2012|title=Phosphate additives in food--a health risk|journal=Deutsches Ärzteblatt International|volume=109|issue=4|pages=49–55|doi=10.3238/arztebl.2012.0049|issn=1866-0452|pmc=3278747|pmid=22334826}}</ref>

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* '''Oceania''': [[Australia]], [[Makatea]], [[Nauru]], and [[Banaba Island]]

In 2007, at the current rate of consumption, the supply of phosphorus was estimated to run out in 345 years.<ref>{{cite journal|date=May 26, 2007|journal = [[New Scientist]]|volume = 194|issue = 2605|pages = 38–9|title = How Long Will it Last?|doi=10.1016/S0262-4079(07)61508-5|bibcode = 2007NewSc.194...38R |last1 = Reilly|first1 = Michael}}</ref> However, some scientists thought that a "[[peak phosphorus]]" would occur in 30 years and [[Dana Cordell]] from Institute for Sustainable Futures said <!-- in Times --> that at "current rates, reserves will be depleted in the next 50 to 100 years".<ref name=Lewis>{{cite news|url = http://business.timesonline.co.uk/tol/business/industry_sectors/natural_resources/article4193017.ece|archive-url = https://web.archive.org/web/20080905082511/http://business.timesonline.co.uk/tol/business/industry_sectors/natural_resources/article4193017.ece|url-status = dead|archive-date = September 5, 2008|title = Scientists warn of lack of vital phosphorus as biofuels raise demand|date = 2008-06-23|author = Leo Lewis|newspaper = The Times}}</ref> Reserves refer to the amount assumed recoverable at current market prices. In 2012 the [[United States Geological Survey|USGS]] estimated world reserves at 71 billion tons, while 0.19 billion tons were mined globally in 2011.<ref>U.S. Geological Survey [http://minerals.usgs.gov/minerals/pubs/commodity/phosphate_rock/mcs-2012-phosp.pdf Phosphate Rock]</ref> Phosphorus comprises 0.1% by mass of the average rock<ref>[[U.S. Geological Survey]] {{cite web| url = http://pubs.usgs.gov/of/2004/1368/Soil_PDFs/P_soils_page.pdf| title = Phosphorus Soil Samples}}</ref> (while, for perspective, its typical concentration in vegetation is 0.03% to 0.2%),<ref>{{cite web|author=Floor Anthoni |url=http://www.seafriends.org.nz/oceano/abund.htm |title=Abundance of Elements |publisher=Seafriends.org.nz |access-date=2013-01-10}}</ref> and consequently there are quadrillions of tons of phosphorus in Earth's 3×10<sup>19</sup>-ton crust,<ref>[[American Geophysical Union]], Fall Meeting 2007, abstract #V33A-1161. [http://adsabs.harvard.edu/abs/2007AGUFM.V33A1161P Mass and Composition of the Continental Crust]</ref> albeit at predominantly lower concentration than the deposits counted as reserves, which are inventoried and cheaper to extract. If it is assumed that the phosphate minerals in [[phosphate rock]] are mainly hydroxyapatite and fluoroapatite, phosphate minerals contain roughly 18.5% phosphorus by weight. If phosphate rock contains around 20% of these minerals, the average phosphate rock has roughly 3.7% phosphorus by weight.

Some phosphate rock deposits, such as [[Mulberry, Florida#Economy|Mulberry]] in Florida,<ref name="Mulberry, Phosphate" /> are notable for their inclusion of significant quantities of radioactive uranium isotopes. This is a concern because radioactivity can be released into surface waters<ref>{{cite encyclopedia |author=C. Michael Hogan |year=2010 |url=http://www.eoearth.org/article/Water_pollution |title=Water pollution |encyclopedia=[[Encyclopedia of Earth]] |editor=Mark McGinley and C. Cleveland (Washington, DC.: [[National Council for Science and the Environment]]) |archive-url=https://web.archive.org/web/20100916050147/http://www.eoearth.org/article/Water_pollution |archive-date=2010-09-16}}</ref> from application of the resulting [[Fertilizer#Phosphate fertilizers|phosphate fertilizer]].

In 2021 Norway discovered phosphate deposits almost equal to those in the rest of Earth combined.<ref>{{cite news |url=https://www.dw.com/en/eu-pins-hope-on-norway-raw-materials-discovery/a-56343829 |title=EU pins hope on Norway's raw materials |last1=Bushuev |first1=Mikhail |date=26 January 2021 |accessdate=2 July 2023}}</ref>▼

In December 2012, [[Cominco Resources]] announced an updated [[JORC]] compliant resource of their Hinda project in [[Republic of the Congo|Congo-Brazzaville]] of 531 million tons, making it the largest measured and indicated phosphate deposit in the world.<ref>{{cite web|title=Updated Hinda Resource Announcement: Now world's largest phosphate deposit (04/12/2012)|url=http://www.comincoresources.com/news/updated-hinda-resource-announcement-now-worlds-largest-phosphate-deposit-04|publisher=[[Cominco Resources]]|access-date=2013-05-03|archive-url=https://web.archive.org/web/20161005113748/http://www.comincoresources.com/news/updated-hinda-resource-announcement-now-worlds-largest-phosphate-deposit-04|archive-date=2016-10-05|url-status=dead}}</ref>

▲InAround 20212018, Norway discovered phosphate deposits almost equal to those in the rest of Earth combined.<ref>{{cite news |url=https://www.dw.com/en/eu-pins-hope-on-norway-raw-materials-discovery/a-56343829 |title=EU pins hope on Norway's raw materials |last1=Bushuev |first1=Mikhail |date=26 January 2021 |accessdate=2 July 2023}}</ref><ref>{{cite web | url=https://www.euractiv.com/section/energy-environment/news/great-news-eu-hails-discovery-of-massive-phosphate-rock-deposit-in-norway/ | title='Great news': EU hails discovery of massive phosphate rock deposit in Norway | date=29 June 2023 }}</ref>

In July 2022 China announced quotas on phosphate exportation.<ref>{{cite news | url=https://www.reuters.com/article/china-fertilizers-quotas/china-issues-phosphate-quotas-to-rein-in-fertiliser-exports-analysts-idUSKBN2OQ0KY | title=China issues phosphate quotas to rein in fertiliser exports - analysts | newspaper=Reuters | date=15 July 2022 }}</ref>

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===Mining===

[[File:International Exchange of Phosphates in 1937 - DPLA - 03790fc57d3206e73683a68ec11c8fb2.jpg|thumb|right|Phosphate imports/exports in 1937]]

The three principal phosphate producer countries (China, Morocco and the United States) account for about 70% of world production.

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Calcium hydroxyapatite and calcite precipitates can be found around [[bacteria]] in [[alluvial]] topsoil.<ref name=Schmittner>{{cite journal |author=Schmittner KE, Giresse P |title=Micro-environmental controls on biomineralization: superficial processes of apatite and calcite precipitation in Quaternary soils, Roussillon, France |journal=Sedimentology |volume=46 |issue=3 |year=1999 |pages=463–76 |doi=10.1046/j.1365-3091.1999.00224.x|bibcode=1999Sedim..46..463S |s2cid=140680495 }}</ref> As clay minerals promote biomineralization, the presence of bacteria and clay minerals resulted in calcium hydroxyapatite and calcite precipitates.<ref name=Schmittner/>

Phosphate deposits can contain significant amounts of naturally occurring heavy metals. Mining operations processing [[phosphate rock]] can leave [[tailings]] piles containing elevated levels of [[cadmium]], [[lead]], [[nickel]], [[copper]], [[chromium]], and [[uranium]]. Unless carefully managed, these waste products can leach heavy metals into groundwater or nearby estuaries. Uptake of these substances by plants and marine life can lead to concentration of toxic heavy metals in food products.<ref>{{cite journal|last1 = Gnandi|first1 = K.|last2 = Tchangbedjil|first2 = G.|last3 = Killil|first3 = K.|last4 = Babal|first4 = G.|last5 = Abbel|first5 = E.|title = The Impact of Phosphate Mine Tailings on the Bioaccumulation of Heavy Metals in Marine Fish and Crustaceans from the Coastal Zone of Togo|periodical = Mine Water and the Environment|volume = 25|issue = 1|date = March 2006|pages = 56–62|doi = 10.1007/s10230-006-0108-4| bibcode=2006MWE....25...56G |s2cid = 129497587}}</ref>

==See also==

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* [[Fertilizer]]

* [[Hypophosphite]] – {{chem|H|2|(PO|2|)|−}}

* [[Metaphosphate]] – {{chem|(P|O|3|)|''n''}}

* [[Monosodium phosphate]] – NaH<sub>2</sub>PO<sub>4</sub>

* [[Organophosphorus]] compounds