Aluminium phosphate
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This article needs additional citations for verification. (August 2009) |
| Aluminium phosphate | |
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Other names
Aluminum monophosphate |
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| Identifiers | |
| CAS number | 7784-30-7  22784-12-9 (trihydrate) |
| PubChem | 64655 |
| ChemSpider | 58204 |
| UNII | F92V3S521O |
| RTECS number | TB6450000 |
| ATC code | A02 |
| Jmol-3D images | Image 1 Image 2 |
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| Properties | |
| Molecular formula | AlPO4 |
| Molar mass | 121.9529 g/mol |
| Appearance | white, crystalline powder |
| Density | 2.566 g/cm3, solid |
| Melting point |
1800 °C |
| Boiling point |
decomposes |
| Solubility in water | insoluble |
| Solubility product, Ksp | 9.83×10−10 |
| Solubility | very slightly soluble in HCl and HNO3 |
| Refractive index (nD) | 1.546 [1] |
| Hazards | |
| EU classification | Xi |
| R-phrases | R36/37/38 |
| S-phrases | S26 |
| NFPA 704 |
 0
2
0
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| LD50 | 4640mg/kg (rat, oral) > 4640 mg/kg (rabbit, dermal) |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Aluminium phosphate (AlPO4) is a chemical compound. The anhydrous form is found in nature as the mineral berlinite. Many synthetic forms[2] of anhydrous aluminium phosphate are known. They have framework structures similar to zeolites and some are used as catalysts or molecular sieves. A hydrated form,AlPO4.1.5H2O is known.[3] Commercially an aluminium phosphate gel is available.
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Aluminium phosphate (berlinite) [edit]
AlPO4 is isoelectronic with Si2O4, silicon dioxide. Berlinite looks like quartz and has a structure that is similar to quartz with silicon replaced by Al and P. The AlO4 and PO4 tetrahedra alternate. Like quartz AlPO4 exhibits chirality[4] and piezoelectric properties.[5] Crystalline AlPO4, berlinite when heated converts to tridymite and cristobalite forms and this mirrors the behaviour of silicon dioxide.[6]
Aluminophosphate molecular sieves [edit]
There are a large number of aluminium phosphate molecular sieves, generically known as 'ALPOs'. The first ones were reported in 1982.[7] They all share the same chemical composition of AlPO4 and have framework structures with microporous cavities and the frameworks are made up of alternating AlO4 and PO4 tetrahedra. The denser cavity-less crystalline AlPO4 mineral, berlinite shares the same alternating AlO4 and PO4 tetrahedra.[6] The aluminophosphate framework structures vary one from another in the orientation of the AlO4 tetrahedra and PO4 tetrahedra to form different sized cavities and in this respect they are similar to the aluminosilicate zeolites which differ in having electrically charged frameworks. A typical preparation of an aluminophosphate involves the hydrothermal reaction of phosphoric acid and aluminium in the form of hydroxide, an aluminium salt such as aluminium nitrate salt or alkoxide under controlled pH in the presence of organic amines.[8] These organic molecules act as templates, (now termed structure directing agents,SDA's.[2]) to direct the growth of the porous framework.[9]
Uses of aluminium phosphate gel [edit]
In medicine an aluminium phosphate sol is used as adsorbent for toxoid and in the dried form, which contains hydrated AlPO4, as an antacid [10] Industrially the Al-PO4-H2O system is used as the basis of many adhesives, binders and cements.[6]
Naturally occurring aluminium phosphate [edit]
Although it is unstable to heat, in geologically stable regions like Australia and Southern Africa, aluminum phosphate, is generally the most common form of phosphorus in soils, as it forms when phosphate in rainwater reacts with dissolved aluminium in the soil. Although it is not as insoluble as many other components of soils in those regions, aluminium phosphate can form exceedingly insoluble double salts known as taranakites with many essential elements for plant growth that are normally highly soluble in water, such as potassium and nitrogen.
In coastal areas of South Africa and Namibia, the combination of exceedingly old soils and a high input of phosphate from very fertile oceans due to the Benguela Current causes aluminum phosphate to accumulate to form a concentrated mineral, known as aluminum phosphate rock. Only in recent years has there been any interest in the mining of these considerable deposits as a source of phosphorus for agriculture, but there could be considerable economic value if low-cost treatment becomes possible.
References [edit]
- ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
- ^ a b Chemistry of Zeolites and Related Porous Materials: Synthesis and Structure Ruren Xu, Wenqin Pang, Jihong Yu, Qisheng Huo, Jiesheng Chen, John Wiley & Sons, 2007, ISBN 978-0-470-82233-3
- ^ Lagno, Felipe; Demopoulos, George P. (2005). "Synthesis of Hydrated Aluminum Phosphate, AlPO4·1.5H2O (AlPO4−H3), by Controlled Reactive Crystallization in Sulfate Media". Industrial & Engineering Chemistry Research 44 (21): 8033–8038. doi:10.1021/ie0505559. ISSN 0888-5885.
- ^ Tanaka, Yoshikazu; Kojima, Taro; Takata, Yasutaka; Chainani, Ashish; Lovesey, Stephen W.; Knight, Kevin S.; Takeuchi, Tomoyuki; Oura, Masaki; Senba, Yasunori; Ohashi, Haruhiko; Shin, Shik (2010). "Determination of structural chirality of berlinite and quartz using resonant x-ray diffraction with circularly polarized x-rays". Physical Review B 81 (14). doi:10.1103/PhysRevB.81.144104. ISSN 1098-0121.
- ^ Crystal growth of an α-quartz like piezoelectric material, berlinite, Motchany A.I.,Chvanski P.P., Annales de Chimie Science des Materiaux properties, 2001,26, 199
- ^ a b c Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth–Heinemann. ISBN 0080379419.
- ^ Wilson, Stephen T.; Lok, Brent M.; Messina, Celeste A.; Cannan, Thomas R.; Flanigen, Edith M. (1982). "Aluminophosphate molecular sieves: a new class of microporous crystalline inorganic solids". Journal of the American Chemical Society 104 (4): 1146–1147. doi:10.1021/ja00368a062. ISSN 0002-7863.
- ^ Zeolites in Industrial Separation and Catalysis Santi Kulprathipanja, John Wiley & Sons, 26 Jan 2010
- ^ Zeolites and Catalysis, Jiri Cejka, Avelino Corma, Stacey Zones, John Wiley & Sons, 27 May 2010,isbn: 978-3-527-32514-6
- ^ Contemporary Drug Synthesis, Jie Jack Li, Douglas S. Johnson, Drago R. Sliskovic, Bruce D. Roth., John Wiley and Sons, 2004, isbn:0471-21-480-9
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