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EC number: 231-208-1
CAS number: 7446-70-0
The forms of aluminium present in the
environment depend on many factors, especially pH, alkalinity,
temperature, dissolved organic carbon, dissolved inorganic carbon and
anion concentration. Aluminium, as a metal, is insoluble in water. In
contrast, aluminium chloride is highly soluble in water and dissociating
to aluminium hydroxide and hydrochloric acid. Depending on the buffer
capacity of an aquatic system AlCl3 may change the pH towards acidic.
The pH of an aquatic system is also important for any further reactions
and the distribution of AlCl3. At pH < 5.5 Al3+ becomes the prevalent
form. At higher pH >8.0 the more soluble Al(OH)4- species predominate.
As already mentioned, under circum neutral conditions AlCl3 will
dissociate to Al(OH)3 and HCl. However, in natural waters, the chemistry
of aluminium becomes more complicated due to the presence of alternative
ligands like naturally occurring organic substances (including humic and
fulvic acids) and inorganic minerals, which compete for complexation
with the hydroxide ion. Thus, under relevant environmental pH conditions
Al3+ will react to aluminium hydroxide which is forming complexes,
precipitating to gibbsite, or Al3+ adsorb immediately to organic as well
as to inorganic particles.
In conclusion, at pH values between 5.5 and
8.0 AlCl3 will dissociate in water into Cl- and Al3+ ions. The latter
may adsorb immediately to organic particles and precipitates, forms
inorganic alumino-silicate minerals (clay and silt) or reacts to
- Environment Agency (2007). Science Report
Proposed EQS for aluminium, Feb 2007
- Environment Canada (2000). State of
science report for Aluminium chloride, Aluminium nitrate and Aluminium
sulphate, Canadian Environmental Protection Act, Dec 2000
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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