Hydrous oxide

{{Short description|Inorganic compound}}

Hydrous oxides are inorganic compounds of a metal, hydroxide, and weakly bound water. Some examples include:

• Hydrous ferric oxide (HFO){{Cite journal | doi = 10.1021/j150202a003 | title = Hydrous Oxides. I | year = 1920 | last1 = Weiser | first1 = H. B. | journal = The Journal of Physical Chemistry | volume = 24 | issue = 4 | pages = 277–328 | url = https://zenodo.org/record/1861992 }}
• Hydrous cupric oxide{{Cite journal | doi = 10.1021/j150231a001 | title = Hydrous Oxides. V | year = 1923 | last1 = Weiser | first1 = H. B. | journal = The Journal of Physical Chemistry | volume = 27 | issue = 6 | pages = 501–532 }}
• Hydrous thorium oxide (THO) and hydrous titanium oxide (TiHO) {{cite journal | doi = 10.1016/0022-1902(66)80129-X | title = Hydrous oxides and their cation exchange properties—II Structure and equilibrium experiments | year = 1966 | last1 = Heitner-Wirguin | first1 = C. | last2 = Albu-Yaron | first2 = A. | journal = Journal of Inorganic and Nuclear Chemistry | volume = 28 | issue = 10 | pages = 2379–2384 }}
• Hydrous aluminum oxide (HAO){{cite journal | doi = 10.1006/jcis.1999.6507 | title = Surface Complexation Modeling of Copper Sorption by Hydrous Oxides of Iron and Aluminum | year = 1999 | last1 = Karthikeyan | first1 = K.G | last2 = Elliott | first2 = Herschel A. | journal = Journal of Colloid and Interface Science | volume = 220 | issue = 1 | pages = 88–95 | pmid = 10550244 | bibcode = 1999JCIS..220...88K }}

Some of them, such as HFO and HAO, are precipitated in highly porous poorly crystalline or amorphous forms and therefore are good adsorbents used for example in water treatment.{{Cite book|url=https://books.google.com/books?id=vRovU0TD8s0C&pg=PA265|title=Water Quality Engineering: Physical / Chemical Treatment Processes|isbn=9781118632277|last1=Benjamin|first1=Mark M.|last2=Lawler|first2=Desmond F.|date=13 June 2013}}

Some others are gels.

Hydrous oxide films may be used an various applications such as electrocatalysis, supercapacitors, and sensors.{{Cite book|url=https://books.google.com/books?id=AekdKO-pimUC&pg=PA194|title=Proceedings of the Third Symposium on Electrochemically Deposited Thin Films|isbn=9781566771696|last1=Paunovic|first1=Milan|last2=Scherson|first2=Daniel|year=1997}}{{Cite book|url=https://books.google.com/books?id=M74FAswC1F0C&pg=PA52|title = Micropower and Microdevices: Proceedings of the International Symposium|isbn = 9781566773874|last1 = Brandon|first1 = Erik J.|year = 2003}}

HFO and HAO may also result from oxidative weathering of rocks to produce iron an aluminum hydrous oxide clay soils.{{Cite book|url=https://books.google.com/books?id=Jxlx4g4cdisC&pg=PA1|title = Prospects for the Drainage of Clay Soils|isbn = 9789251036242|last1 = Rycroft|first1 = David W.|last2 = Amer|first2 = M. H.|year = 1995}}