Registration Dossier
Registration Dossier
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EC number: 235-101-0 | CAS number: 12068-53-0
Hydrolysis
Administrative data
Link to relevant study record(s)
Description of key information
In accordance with column 2 of Annex VIII, 9.2.2.1 of Regulation (EC) No 1907/2006, testing for hydrolysis is not required as the substance is highly insoluble in water.
Key value for chemical safety assessment
Additional information
In accordance with column 2 of Annex VIII, 9.2.2.1 of Regulation (EC) No 1907/2006, testing for hydrolysis is not required as the substance has shown to be highly insoluble in water.
Furthermore, the behaviour of the individual metals in aqueous solutions is well described in existing literature. Hydrolysis of aluminium ions has two possible “directions” towards a neutral pH, i.e. base hydrolysis and acid hydrolysis. Both acid and base hydrolysis of aluminum result in form of poorly soluble aluminium hydroxide. This hydrolysis reaction is very rapid, and is completed within 1-7 seconds (Lettermann et al. 1973). Aluminium hydroxide is amphoteric and soluble in both strong acids and bases. In acidic solution (pH < 4) aluminium hydroxide dissolves to form mostly Al3+ ions (or more specific as Al(H2O)63- ions) and in alkaline solution (pH > 8) the aluminate ion, Al(OH)4- ion is the totally dominating species (Szabo et al. 1978). At pH 4.0, mono- and dimeric aluminum species [Al(OH)2(H2O)2-3]+ and [Al2O2(OH)(H2O)0-5]+ were detected as main products. With increasing pH, hydrolysis and polymerization increased. At pH 5.0, aluminum species mainly aggregated and assembled to median polymeric species (Al6-Al10 species) and these further to large polymeric species (Al11- Al21). At pH 5.8 metastable median and large polymers decomposed into small aluminium species and disaggregated into dimeric species. With pH 6.4 the majority of aluminum formed to Al(OH)3 amorphous flocs (Zhao et al. 2009).
Zinc in fresh water or seawater can occur in both suspended and dissolved forms and is partitioned over a number of chemical species. Zinc in freshwater can be divided in several classes, as for instance hydrated zinc ions, zinc ions complexed by organic ligands (humic and fulvic acids), zinc oxy ions and zinc adsorbed to solid matter. The distribution over free zinc and zinc complexes has been found to be roughly 30% and 70%, respectively, in European surface waters (Cleven et al., 1993; Jansen et al., 1998).
References:
Cleven, R.M.F.J., Janus, J.A., Annema, J.A and Slooff, W. (Eds.). 1993. Integrated Criteria Document Zinc. RIVM report 710401028, National Institute of Public Health and the Environment, Bilthoven, The Netherlands. (Originally published in 1992, as RIVM-Report 710401019: “Basisdocument Zink”, In Dutch).
Jansen, R.A.G., H.P. van Leeuwen, R.F.M.J. Cleven and M.A.G.T. van den Hoop. 1998. Speciation and lability of zinc(II) in river waters. Environ. Sci. Technol. 32, 3882-3886.
Zhao et al., Effect of pH on the aluminum salts hydrolysis during coagulation process: Formation and decomposition of polymeric aluminum species. Journal of Colloid and Interface Science 330: 105-112 (2009).
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.
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