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| Odor = odorless
| Odor = odorless
| Density = 5.2 g/cm<sup>3</sup>, α-form <br> 5.67 g/cm<sup>3</sup> β-form
| Density = 5.2 g/cm<sup>3</sup>, α-form <br> 5.67 g/cm<sup>3</sup> β-form
| Solubility = Dissolved concentration of 370 ± 37 µg/L was obtained with a loading of 10 mg/L after 7 days of exposure. Temperature varied between 20.8°C (t=0; start of the test) and 22.9°C
| Solubility = {{val|370|37}} μg/L between 20.8&nbsp;°C and 22.9&nbsp;°C
| SolubleOther = soluble in acid
| SolubleOther = soluble in acid
| MeltingPtC = 656
| MeltingPtC = 656
Line 41: Line 41:
| pKa =
| pKa =
| RefractIndex = 2.087, α-form <br> 2.35, β-form
| RefractIndex = 2.087, α-form <br> 2.35, β-form
| MagSus = -69.4·10<sup>−6</sup> cm<sup>3</sup>/mol
| MagSus = {{val|-69.4e-6|u=cm<sup>3</sup>/mol}}
}}
}}
|Section3={{Chembox Structure
|Section3={{Chembox Structure
| Coordination = pyramidal
| Coordination = pyramidal
| CrystalStruct = [[Cubic crystal system|cubic]] (α)<570 °C<br />[[orthorhombic]] (β) >570 °C
| CrystalStruct = [[Cubic crystal system|cubic]] (α) <&nbsp;570&nbsp;°C<br />[[orthorhombic]] (β) >&nbsp;570&nbsp;°C
| Dipole = zero
| Dipole = zero
}}
}}
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}}
}}
|Section8={{Chembox Related
|Section8={{Chembox Related
| OtherAnions = [[Antimony trisulfide]]
| OtherAnions = [[Antimony trisulfide]]<br>[[Antimony triselenide]]<br>[[Antimony telluride]]
| OtherCations = [[Bismuth trioxide]]
| OtherCations = [[Dinitrogen trioxide]]<br>[[Phosphorus trioxide]]<br>[[Arsenic trioxide]]<br>[[Bismuth trioxide]]
| OtherCompounds = [[Diantimony tetraoxide]]<br />[[Antimony pentoxide]]
| OtherCompounds = [[Diantimony tetraoxide]]<br />[[Antimony pentoxide]]
}}
}}
}}
}}


'''Antimony(III) oxide''' is the [[inorganic compound]] with the [[Chemical formula|formula]] Sb<sub>2</sub>O<sub>3</sub>. It is the most important commercial compound of [[antimony]]. It is found in nature as the minerals [[valentinite]] and [[senarmontite]].<ref>Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. {{ISBN|0-7506-3365-4}}.</ref> Like most polymeric [[oxide]]s, Sb<sub>2</sub>O<sub>3</sub> dissolves in aqueous solutions with [[hydrolysis]].
'''Antimony(III) oxide''' is the [[inorganic compound]] with the [[Chemical formula|formula]] Sb<sub>2</sub>O<sub>3</sub>. It is the most important commercial compound of [[antimony]]. It is found in nature as the minerals [[valentinite]] and senarmontite.<ref>Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. {{ISBN|0-7506-3365-4}}.</ref> Like most polymeric [[oxide]]s, Sb<sub>2</sub>O<sub>3</sub> dissolves in aqueous solutions with [[hydrolysis]]. A mixed arsenic-antimony oxide occurs in nature as the very rare mineral stibioclaudetite.<ref>{{Cite web|url=https://www.mindat.org/min-32285.html|title = Stibioclaudetite}}</ref><ref>{{Cite web|url=https://www.ima-mineralogy.org/Minlist.htm|title=List of Minerals|date=21 March 2011}}</ref>


==Production and properties==
==Production and properties==
Global production of antimony(III) oxide in 2012 was 130,000 tonnes, an increase from 112,600 tonnes in 2002. China produces the largest share followed by US/Mexico, Europe, Japan and South Africa and other countries (2%).<ref>{{cite web|url=http://esis.jrc.ec.europa.eu/doc/risk_assessment/REPORT/datreport415.pdf |title=Archived copy |accessdate=2014-01-06 |deadurl=yes |archiveurl=https://web.archive.org/web/20140106155610/http://esis.jrc.ec.europa.eu/doc/risk_assessment/REPORT/datreport415.pdf |archivedate=2014-01-06 |df= }}</ref>
Global production of antimony(III) oxide in 2012 was 130,000 tonnes, an increase from 112,600 tonnes in 2002. China produces the largest share followed by US/Mexico, Europe, Japan and South Africa and other countries (2%).<ref>{{cite report|url=http://esis.jrc.ec.europa.eu/doc/risk_assessment/REPORT/datreport415.pdf |title=European Union Risk Assessment Report: DIANTIMONY TRIOXIDE (draft)|date=November 2008|location=Sweden|id=CAS No: 1309-64-4; EINECS No: 215-175-0|url-status=dead |archive-url=https://web.archive.org/web/20140106155610/http://esis.jrc.ec.europa.eu/doc/risk_assessment/REPORT/datreport415.pdf |archive-date=2014-01-06 }}</ref>


As of 2010, antimony(III) oxide was produced at four sites in EU27. It is produced via two routes, re-volatilizing of crude antimony(III) oxide and by oxidation of antimony metal.
As of 2010, antimony(III) oxide was produced at four sites in the EU. It is produced via two routes, re-volatilizing of crude antimony(III) oxide and by oxidation of antimony metal.
Oxidation of antimony metal dominates in Europe. Several processes for the production of crude antimony(III) oxide or metallic antimony from virgin material. The choice of process depends on the composition of the ore and other factors. Typical steps include mining, crushing and grinding of ore, sometimes followed by [[froth flotation]] and separation of the metal using pyrometallurgical processes (smelting or roasting) or in a few cases (e.g. when the ore is rich in precious metals) by hydrometallurgical processes. These steps do not take place in the EU but closer to the mining location.
Oxidation of antimony metal dominates in Europe. Several processes for the production of crude antimony(III) oxide or metallic antimony from virgin material. The choice of process depends on the composition of the ore and other factors. Typical steps include mining, crushing and grinding of ore, sometimes followed by [[froth flotation]] and separation of the metal using pyrometallurgical processes (smelting or roasting) or in a few cases (e.g. when the ore is rich in precious metals) by hydrometallurgical processes. These steps do not take place in the EU but closer to the mining location.


===Re-volatilizing of crude antimony(III) oxide===
===Re-volatilizing of crude antimony(III) oxide===
Step 1) Crude stibnite is oxidized to crude antimony(III) oxide using furnaces operating at approximately 500 to 1,000&nbsp;°C. The reaction is the following:
Step 1) Crude stibnite is oxidized to crude antimony(III) oxide using furnaces operating at approximately 500 to 1,000&nbsp;°C. The reaction is the following:
:2 Sb<sub>2</sub>S<sub>3</sub> + 9 O<sub>2</sub> → 2 Sb<sub>2</sub>O<sub>3</sub> + 6 SO<sub>2</sub>
:2&nbsp;Sb<sub>2</sub>S<sub>3</sub> + 9&nbsp;O<sub>2</sub> → 2&nbsp;Sb<sub>2</sub>O<sub>3</sub> + 6&nbsp;SO<sub>2</sub>
Step 2) The crude antimony(III) oxide is purified by sublimation.
Step 2) The crude antimony(III) oxide is purified by sublimation.


===Oxidation of antimony metal===
===Oxidation of antimony metal===
Antimony metal is oxidized to antimony(III) oxide in furnaces. The reaction is exothermic. Antimony(III) oxide is formed through sublimation and recovered in bag filters (bag house). The size of the formed particles is controlled by process conditions in furnace and gas flow. The reaction can be schematically described by:<br />
Antimony metal is oxidized to antimony(III) oxide in furnaces. The reaction is exothermic. Antimony(III) oxide is formed through sublimation and recovered in bag filters. The size of the formed particles is controlled by process conditions in furnace and gas flow. The reaction can be schematically described by:
:4 Sb + 3 O<sub>2</sub> → 2 Sb<sub>2</sub>O<sub>3</sub>
:4&nbsp;Sb + 3&nbsp;O<sub>2</sub> → 2&nbsp;Sb<sub>2</sub>O<sub>3</sub>


===Properties===
===Properties===
Antimony(III) oxide is an [[amphoteric oxide]], it dissolves in aqueous [[sodium hydroxide]] solution to give the meta-antimonite NaSbO<sub>2</sub>, which can be isolated as the trihydrate. Antimony(III) oxide also dissolves in concentrated [[mineral acids]] to give the corresponding salts, which hydrolyzes upon dilution with water.<ref name="InorgChem">{{cite book | title = Inorganic Chemistry | edition = 3rd | chapter = Chapter 15: The group 15 elements | author1 = Housecroft, C. E. | author2 = Sharpe, A. G. | publisher = Pearson | year = 2008 | isbn = 978-0-13-175553-6 | page = 481 }}</ref> With [[nitric acid]], the trioxide is oxidized to [[antimony(V) oxide]].<ref name="Handbook">{{cite book | title = Handbook of Inorganic Chemicals | author = Patnaik, P. | publisher = McGraw-Hill | year = 2002 | isbn = 0-07-049439-8 | page = 56 }}</ref>
Antimony(III) oxide is an [[amphoteric oxide]]. It dissolves in aqueous [[sodium hydroxide]] solution to give the meta-antimonite NaSbO<sub>2</sub>, which can be isolated as the trihydrate. Antimony(III) oxide also dissolves in concentrated [[mineral acids]] to give the corresponding salts, which hydrolyzes upon dilution with water.<ref name="InorgChem">{{cite book | title = Inorganic Chemistry | edition = 3rd | chapter = Chapter 15: The group 15 elements | author1 = Housecroft, C. E. | author2 = Sharpe, A. G. | publisher = Pearson | year = 2008 | isbn = 978-0-13-175553-6 | page = 481 }}</ref> With [[nitric acid]], the trioxide is oxidized to [[antimony(V) oxide]].<ref name="Handbook">{{cite book | title = Handbook of Inorganic Chemicals | author = Patnaik, P. | publisher = McGraw-Hill | year = 2002 | isbn = 0-07-049439-8 | page = 56 }}</ref>


When heated with [[carbon]], the oxide is reduced to [[antimony]] metal. With other reducing agents such as [[sodium borohydride]] or [[lithium aluminium hydride]], the unstable and very toxic gas [[stibine]] is produced.<ref>{{ cite journal |author1=Bellama, J. M. |author2=MacDiarmid, A. G. | title = Synthesis of the Hydrides of Germanium, Phosphorus, Arsenic, and Antimony by the Solid-Phase Reaction of the Corresponding Oxide with Lithium Aluminum Hydride |journal = [[Inorganic Chemistry (journal)|Inorganic Chemistry]] | year = 1968 | volume = 7 | issue = 10 | pages = 2070–2072 | doi = 10.1021/ic50068a024 }}</ref> When heated with [[potassium bitartrate]], a complex salt potassium antimony tartrate, KSb(OH)<sub>2</sub>•C<sub>4</sub>H<sub>2</sub>O<sub>6</sub> is formed.<ref name="Handbook" />
When heated with [[carbon]], the oxide is reduced to [[antimony]] metal. With other reducing agents such as [[sodium borohydride]] or [[lithium aluminium hydride]], the unstable and very toxic gas [[stibine]] is produced.<ref>{{ cite journal |author1=Bellama, J. M. |author2=MacDiarmid, A. G. | title = Synthesis of the Hydrides of Germanium, Phosphorus, Arsenic, and Antimony by the Solid-Phase Reaction of the Corresponding Oxide with Lithium Aluminum Hydride |journal = [[Inorganic Chemistry (journal)|Inorganic Chemistry]] | year = 1968 | volume = 7 | issue = 10 | pages = 2070–2072 | doi = 10.1021/ic50068a024 }}</ref> When heated with [[potassium bitartrate]], a complex salt [[potassium antimony tartrate]], KSb(OH)<sub>2</sub>·C<sub>4</sub>H<sub>2</sub>O<sub>6</sub>, is formed.<ref name="Handbook" />


==Structure==
==Structure==
The structure of Sb<sub>2</sub>O<sub>3</sub> depends on the temperature of the sample. Dimeric Sb<sub>4</sub>O<sub>6</sub> is the high temperature (1560&nbsp;°C<!--seems high-->) gas.<ref name ="Wiberg&Holleman">{{ cite book |author1=Wiberg, E. |author2=Holleman, A. F. | year = 2001 | title = Inorganic Chemistry | publisher = Elsevier | isbn = 0-12-352651-5 }}</ref> Sb<sub>4</sub>O<sub>6</sub> molecules are bicyclic cages, similar to the related oxide of phosphorus(III), [[phosphorus trioxide]].<ref name = "Wells">{{ cite book | author = Wells, A. F. | year = 1984 | title = Structural Inorganic Chemistry | location = Oxford | publisher = Clarendon Press | isbn = 0-19-855370-6 }}</ref> The cage structure is retained in a solid that crystallizes in a cubic habit. The Sb-O distance is 197.7 pm and the O-Sb-O angle of 95.6°.<ref>{{ cite journal | author = Svensson, C. | title = Refinement of the crystal structure of cubic antimony(III) oxide, Sb<sub>2</sub>O<sub>3</sub> | journal = Acta Crystallographica B | year = 1975 | volume = 31 | issue = 8 | pages = 2016–2018 | doi = 10.1107/S0567740875006759 }}</ref> This form exists in nature as the [[mineral]] [[senarmontite]].<ref name = "Wells"/> Above 606&nbsp;°C, the more stable form is [[orthorhombic]], consisting of pairs -Sb-O-Sb-O- chains that are linked by oxide bridges between the Sb centers. This form exists in nature as the mineral [[valentinite]].<ref name = "Wells"/>
The structure of Sb<sub>2</sub>O<sub>3</sub> depends on the temperature of the sample. Dimeric Sb<sub>4</sub>O<sub>6</sub> is the high temperature (1560&nbsp;°C<!--seems high-->) gas.<ref name ="Wiberg&Holleman">{{ cite book |author1=Wiberg, E. |author2=Holleman, A. F. | year = 2001 | title = Inorganic Chemistry | publisher = Elsevier | isbn = 0-12-352651-5 }}</ref> Sb<sub>4</sub>O<sub>6</sub> molecules are bicyclic cages, similar to the related oxide of phosphorus(III), [[phosphorus trioxide]].<ref name = "Wells">{{ cite book | author = Wells, A. F. | year = 1984 | title = Structural Inorganic Chemistry | location = Oxford | publisher = Clarendon Press | isbn = 0-19-855370-6 }}</ref> The cage structure is retained in a solid that crystallizes in a cubic habit. The Sb–O distance is 197.7&nbsp;pm and the O–Sb–O angle of 95.6°.<ref>{{ cite journal | author = Svensson, C. | title = Refinement of the crystal structure of cubic antimony(III) oxide, Sb<sub>2</sub>O<sub>3</sub> | journal = Acta Crystallographica B | year = 1975 | volume = 31 | issue = 8 | pages = 2016–2018 | doi = 10.1107/S0567740875006759 | doi-access = }}</ref> This form exists in nature as the [[mineral]] [[senarmontite]].<ref name = "Wells"/> Above 606&nbsp;°C, the more stable form is [[orthorhombic]], consisting of pairs of -Sb-O-Sb-O- chains that are linked by oxide bridges between the Sb centers. This form exists in nature as the mineral [[valentinite]].<ref name = "Wells"/>


{| class="wikitable" style="margin:1em auto; text-align:center;"
<center>
|[[File:Sb4O6-molecule-from-senarmontite-xtal-2004-3D-balls-B.png|100px]]||[[File:Antimony(III)-oxide-senarmontite-xtal-2004-3D-balls.png|200px]]||[[File:Antimony(III)-oxide-valentinite-xtal-2004-3D-balls.png|220px]]
{|align="center" class="wikitable"
|<center>[[File:Sb4O6-molecule-from-senarmontite-xtal-2004-3D-balls-B.png|100px]]</center>||<center>[[File:Antimony(III)-oxide-senarmontite-xtal-2004-3D-balls.png|200px]]</center>||<center>[[File:Antimony(III)-oxide-valentinite-xtal-2004-3D-balls.png|220px]]</center>
|-
|-
|<center>Sb<sub>4</sub>O<sub>6</sub></center>||<center>senarmontite</center>||<center>valentinite</center>
|Sb<sub>4</sub>O<sub>6</sub>||senarmontite||valentinite
|}
|}
</center>


==Uses==
==Uses==
The annual consumption of antimony(III) oxide in the United States and Europe is approximately 10,000 and 25,000 [[tonne]]s, respectively. The main application is as flame retardant synergist in combination with halogenated materials. The combination of the halides and the antimony is key to the flame-retardant action for polymers, helping to form less flammable chars. Such flame retardants are found in electrical apparatuses, textiles, leather, and coatings.<ref name=Ullmann>{{ Ullmann | author = Grund, S. C. |author2=Hanusch, K. |author3=Breunig, H. J. |author4=Wolf, H. U. | title = Antimony and Antimony Compounds | doi = 10.1002/14356007.a03_055.pub2 }}</ref>
The annual consumption of antimony(III) oxide in the United States and Europe is approximately 10,000 and 25,000 [[tonne]]s, respectively. The main application is as [[flame retardant]] synergist in combination with halogenated materials. The combination of the halides and the antimony is key to the flame-retardant action for polymers, helping to form less flammable chars. Such flame retardants are found in electrical apparatuses, textiles, leather, and coatings.<ref name=Ullmann>{{ Ullmann | author = Grund, S. C. |author2=Hanusch, K. |author3=Breunig, H. J. |author4=Wolf, H. U. | title = Antimony and Antimony Compounds | doi = 10.1002/14356007.a03_055.pub2 }}</ref>


Other applications:
Other applications:
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*Some specialty [[pigments]] contain antimony.
*Some specialty [[pigments]] contain antimony.
*Antimony(III) oxide is a useful [[Catalysis|catalyst]] in the production of [[polyethylene terephthalate]] (PET plastic) and the [[vulcanization]] of rubber.
*Antimony(III) oxide is a useful [[Catalysis|catalyst]] in the production of [[polyethylene terephthalate]] (PET plastic) and the [[vulcanization]] of rubber.
*Antimony(III) oxide is good vomiting agent to induce vomiting.


==Safety==
==Safety==
Antimony(III) oxide has suspected carcinogenic potential for humans.<ref name=Ullmann/> Its [[Threshold Limit Value|TLV]] is 0.5&nbsp;mg/m<sup>3</sup>, as for most antimony compounds.<ref>{{ cite journal |author1=Newton, P. E. |author2=Schroeder, R. E. |author3=Zwick, L. |author4=Serex, T. | title = Inhalation Developmental Toxicity Studies In Rats With Antimony(III) oxide (Sb<sub>2</sub>O<sub>3</sub>) | journal = Toxicologist | year = 2004 | volume = 78 | issue = 1-S | pages = 38 }}</ref><br/>
Antimony(III) oxide has suspected carcinogenic potential for humans.<ref name=Ullmann/> Its [[Threshold Limit Value|TLV]] is 0.5&nbsp;mg/m<sup>3</sup>, as for most antimony compounds.<ref>{{ cite journal |author1=Newton, P. E. |author2=Schroeder, R. E. |author3=Zwick, L. |author4=Serex, T. | title = Inhalation Developmental Toxicity Studies In Rats With Antimony(III) oxide (Sb<sub>2</sub>O<sub>3</sub>) | journal = Toxicologist | year = 2004 | volume = 78 | issue = 1–S | pages = 38 }}</ref> Before 2021, no other human health hazards were identified for antimony(III) oxide, and no risks to human health and the environment were identified from the production and use of antimony trioxide in daily life. However, the 15th Report on Carcinogens released on December 21, 2021, by the [[US Department of Health and Human Services]] categorised antimony(III) oxide as carcinogenic.<ref>{{Cite web |title=15th Report on Carcinogens |url=https://ntp.niehs.nih.gov/whatwestudy/assessments/cancer/roc |access-date=2023-06-15 |website=National Toxicology Program |language=en}}</ref>
No other human health hazards were identified for antimony(III) oxide, and no risks to human health and the environment were identified from the production and use of antimony trioxide in daily life.


==References==
==References==
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* [http://www.antimony.com/ International Antimony Association]
* [http://www.antimony.com/ International Antimony Association]
* [http://www.inchem.org/documents/icsc/icsc/eics0012.htm International Chemical Safety Card 0012]
* [http://www.inchem.org/documents/icsc/icsc/eics0012.htm International Chemical Safety Card 0012]
* [http://www.manymetal.com/Antimony/ Antimony Market And Price]
* [https://web.archive.org/web/20160819095940/http://www.manymetal.com/Antimony/ Antimony Market And Price]
* [http://www.sica-chauny.com/ Société industrielle et chimique de l'Aisne]
* [http://www.sica-chauny.com/ Société industrielle et chimique de l'Aisne]


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{{DEFAULTSORT:Antimony Trioxide}}
{{DEFAULTSORT:Antimony Trioxide}}
[[Category:Antimony compounds]]
[[Category:Antimony(III) compounds]]
[[Category:Oxides]]
[[Category:Oxides]]
[[Category:Inorganic pigments]]
[[Category:Inorganic pigments]]
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[[Category:Sesquioxides]]
[[Category:Sesquioxides]]
[[Category:Adamantane-like molecules]]
[[Category:Adamantane-like molecules]]
[[Category:Flame retardants]]

Latest revision as of 19:28, 21 August 2024

Antimony(III) oxide
Antimony(III) oxide
Names
IUPAC name
Antimony(III) oxide
Other names
Antimony sesquioxide
Antimonous oxide
Flowers of Antimony
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.013.796 Edit this at Wikidata
EC Number
  • 215-474-6
KEGG
RTECS number
  • CC5650000
UNII
  • InChI=1S/3O.2Sb checkY
    Key: ADCOVFLJGNWWNZ-UHFFFAOYSA-N checkY
  • InChI=1/3O.2Sb/rO3Sb2/c1-4-3-5-2
    Key: ADCOVFLJGNWWNZ-VTKDZCJOAA
  • O=[Sb]O[Sb]=O
Properties
Sb2O3
Molar mass 291.518 g/mol
Appearance white solid
Odor odorless
Density 5.2 g/cm3, α-form
5.67 g/cm3 β-form
Melting point 656 °C (1,213 °F; 929 K)
Boiling point 1,425 °C (2,597 °F; 1,698 K) (sublimes)
370±37 μg/L between 20.8 °C and 22.9 °C
Solubility soluble in acid
−69.4×10−6 cm3/mol
2.087, α-form
2.35, β-form
Structure
cubic (α) < 570 °C
orthorhombic (β) > 570 °C
pyramidal
zero
Hazards
GHS labelling:
GHS08: Health hazard[1]
Warning[1]
H351[1]
P281[1]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
0
0
Lethal dose or concentration (LD, LC):
7000 mg/kg, oral (rat)
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 0.5 mg/m3 (as Sb)[2]
REL (Recommended)
TWA 0.5 mg/m3 (as Sb)[2]
Related compounds
Other anions
Antimony trisulfide
Antimony triselenide
Antimony telluride
Other cations
Dinitrogen trioxide
Phosphorus trioxide
Arsenic trioxide
Bismuth trioxide
Related compounds
Diantimony tetraoxide
Antimony pentoxide
Supplementary data page
Antimony trioxide (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Antimony(III) oxide is the inorganic compound with the formula Sb2O3. It is the most important commercial compound of antimony. It is found in nature as the minerals valentinite and senarmontite.[3] Like most polymeric oxides, Sb2O3 dissolves in aqueous solutions with hydrolysis. A mixed arsenic-antimony oxide occurs in nature as the very rare mineral stibioclaudetite.[4][5]

Production and properties

[edit]

Global production of antimony(III) oxide in 2012 was 130,000 tonnes, an increase from 112,600 tonnes in 2002. China produces the largest share followed by US/Mexico, Europe, Japan and South Africa and other countries (2%).[6]

As of 2010, antimony(III) oxide was produced at four sites in the EU. It is produced via two routes, re-volatilizing of crude antimony(III) oxide and by oxidation of antimony metal. Oxidation of antimony metal dominates in Europe. Several processes for the production of crude antimony(III) oxide or metallic antimony from virgin material. The choice of process depends on the composition of the ore and other factors. Typical steps include mining, crushing and grinding of ore, sometimes followed by froth flotation and separation of the metal using pyrometallurgical processes (smelting or roasting) or in a few cases (e.g. when the ore is rich in precious metals) by hydrometallurgical processes. These steps do not take place in the EU but closer to the mining location.

Re-volatilizing of crude antimony(III) oxide

[edit]

Step 1) Crude stibnite is oxidized to crude antimony(III) oxide using furnaces operating at approximately 500 to 1,000 °C. The reaction is the following:

2 Sb2S3 + 9 O2 → 2 Sb2O3 + 6 SO2

Step 2) The crude antimony(III) oxide is purified by sublimation.

Oxidation of antimony metal

[edit]

Antimony metal is oxidized to antimony(III) oxide in furnaces. The reaction is exothermic. Antimony(III) oxide is formed through sublimation and recovered in bag filters. The size of the formed particles is controlled by process conditions in furnace and gas flow. The reaction can be schematically described by:

4 Sb + 3 O2 → 2 Sb2O3

Properties

[edit]

Antimony(III) oxide is an amphoteric oxide. It dissolves in aqueous sodium hydroxide solution to give the meta-antimonite NaSbO2, which can be isolated as the trihydrate. Antimony(III) oxide also dissolves in concentrated mineral acids to give the corresponding salts, which hydrolyzes upon dilution with water.[7] With nitric acid, the trioxide is oxidized to antimony(V) oxide.[8]

When heated with carbon, the oxide is reduced to antimony metal. With other reducing agents such as sodium borohydride or lithium aluminium hydride, the unstable and very toxic gas stibine is produced.[9] When heated with potassium bitartrate, a complex salt potassium antimony tartrate, KSb(OH)2·C4H2O6, is formed.[8]

Structure

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The structure of Sb2O3 depends on the temperature of the sample. Dimeric Sb4O6 is the high temperature (1560 °C) gas.[10] Sb4O6 molecules are bicyclic cages, similar to the related oxide of phosphorus(III), phosphorus trioxide.[11] The cage structure is retained in a solid that crystallizes in a cubic habit. The Sb–O distance is 197.7 pm and the O–Sb–O angle of 95.6°.[12] This form exists in nature as the mineral senarmontite.[11] Above 606 °C, the more stable form is orthorhombic, consisting of pairs of -Sb-O-Sb-O- chains that are linked by oxide bridges between the Sb centers. This form exists in nature as the mineral valentinite.[11]

Sb4O6 senarmontite valentinite

Uses

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The annual consumption of antimony(III) oxide in the United States and Europe is approximately 10,000 and 25,000 tonnes, respectively. The main application is as flame retardant synergist in combination with halogenated materials. The combination of the halides and the antimony is key to the flame-retardant action for polymers, helping to form less flammable chars. Such flame retardants are found in electrical apparatuses, textiles, leather, and coatings.[13]

Other applications:

Safety

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Antimony(III) oxide has suspected carcinogenic potential for humans.[13] Its TLV is 0.5 mg/m3, as for most antimony compounds.[14] Before 2021, no other human health hazards were identified for antimony(III) oxide, and no risks to human health and the environment were identified from the production and use of antimony trioxide in daily life. However, the 15th Report on Carcinogens released on December 21, 2021, by the US Department of Health and Human Services categorised antimony(III) oxide as carcinogenic.[15]

References

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  1. ^ a b c d Record of Antimony trioxide in the GESTIS Substance Database of the Institute for Occupational Safety and Health, accessed on 23 August 2017.
  2. ^ a b NIOSH Pocket Guide to Chemical Hazards. "#0036". National Institute for Occupational Safety and Health (NIOSH).
  3. ^ Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.
  4. ^ "Stibioclaudetite".
  5. ^ "List of Minerals". 21 March 2011.
  6. ^ European Union Risk Assessment Report: DIANTIMONY TRIOXIDE (draft) (PDF) (Report). Sweden. November 2008. CAS No: 1309-64-4; EINECS No: 215-175-0. Archived from the original (PDF) on 2014-01-06.
  7. ^ Housecroft, C. E.; Sharpe, A. G. (2008). "Chapter 15: The group 15 elements". Inorganic Chemistry (3rd ed.). Pearson. p. 481. ISBN 978-0-13-175553-6.
  8. ^ a b Patnaik, P. (2002). Handbook of Inorganic Chemicals. McGraw-Hill. p. 56. ISBN 0-07-049439-8.
  9. ^ Bellama, J. M.; MacDiarmid, A. G. (1968). "Synthesis of the Hydrides of Germanium, Phosphorus, Arsenic, and Antimony by the Solid-Phase Reaction of the Corresponding Oxide with Lithium Aluminum Hydride". Inorganic Chemistry. 7 (10): 2070–2072. doi:10.1021/ic50068a024.
  10. ^ Wiberg, E.; Holleman, A. F. (2001). Inorganic Chemistry. Elsevier. ISBN 0-12-352651-5.
  11. ^ a b c Wells, A. F. (1984). Structural Inorganic Chemistry. Oxford: Clarendon Press. ISBN 0-19-855370-6.
  12. ^ Svensson, C. (1975). "Refinement of the crystal structure of cubic antimony(III) oxide, Sb2O3". Acta Crystallographica B. 31 (8): 2016–2018. doi:10.1107/S0567740875006759.
  13. ^ a b Grund, S. C.; Hanusch, K.; Breunig, H. J.; Wolf, H. U. "Antimony and Antimony Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_055.pub2. ISBN 978-3527306732.
  14. ^ Newton, P. E.; Schroeder, R. E.; Zwick, L.; Serex, T. (2004). "Inhalation Developmental Toxicity Studies In Rats With Antimony(III) oxide (Sb2O3)". Toxicologist. 78 (1–S): 38.
  15. ^ "15th Report on Carcinogens". National Toxicology Program. Retrieved 2023-06-15.

Further reading

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  • Institut national de recherche et de sécurité (INRS), Fiche toxicologique nº 198 : Trioxyde de diantimoine, 1992.
  • The Oxide Handbook, G.V. Samsonov, 1981, 2nd ed. IFI/Plenum, ISBN 0-306-65177-7
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