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Diss Factsheets
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EC number: 914-920-3 | CAS number: -
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Hydrolysis
Administrative data
Link to relevant study record(s)
- Endpoint:
- hydrolysis
- Data waiving:
- study scientifically not necessary / other information available
- Justification for data waiving:
- other:
- Endpoint:
- hydrolysis
- Type of information:
- migrated information: read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Acceptable, well documented publication which meets basic scientific principles.
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Determination of pH effect on hydrolysis of aluminium chloride at low concentrations (1.5*10E-4 mol/L) was performed by using electrospray ionization mass spectrometry (ESI).
- GLP compliance:
- no
- Radiolabelling:
- no
- Analytical monitoring:
- yes
- Details on sampling:
- The sample was prepared freshly before each experiment. The test substance was diluted to a concentration of 1.5*10E-4 mol/L.
The pH values of fresh solutions were adjusted after dilution. - Buffers:
- - The aged solutions were first diluted, then pH was adjusted after an aging time. Tetramethylammonium hydroxide pentahydrate, (CH3)4NOH.5H2O (TMA, Analytical Reagent, Beijing Chemical Reagents Company) or HCl solution was added into the solution to control pH.
- For the calibration of pH electrode, two buffers with pH 4.01 and 7.00 were prepared. - Endpoint:
- hydrolysis
- Type of information:
- migrated information: read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Acceptable, well documented publication which meets basic scientific principles
- Principles of method if other than guideline:
- Isopiestic measurements were used to determine the change of the water activity due to the variation of the aluminium content of alkaline aluminate solutions (method described in Szabo et al. 1975).
- Radiolabelling:
- no
- Analytical monitoring:
- yes
- Estimation method (if used):
- Gibbs-Duehm equation; initial
Referenceopen allclose all
Results:
At the initial Al concentration of the coagulant (0.55 mol/L), hydrolysis of aluminum salts was very slow. When the AlCl3was diluted to a concentration of 1.5 *10E-4 mol/L, hydrolysis occurred immediately. 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 4.8, mono- and dimeric aluminum species hydrolyzed and polymerized into small polymeric aluminum species (Al3-Al5). The dimers still dominated in the spectra, trimers[Al3O4(H2O)0-5]+was also detected as major species. At pH 5.0, aluminum species mainly aggregated and assemblied to median polymeric species (Al6-Al10species) and these to large polymeric species (Al11- Al21). At pH 5.8, metastable median and large polymers decomposed into small alluminum species and disaggregated into dimeric species. With pH 6.4, the majority of aluminum formed to Al(OH)3amorphous flocs.
Accordingly, hydrolysis mechanism from polymerization toward decomposition was proposed.
Results:
There was a general increase of water activity with increasing aluminium concentration.It can be attributed to two processes: 1) the coordination of hydroxide ion to aluminium; 2) dimerization connected with the dehydration of the monomeric species.
On the basis of the GIBBS-DUHEM equation the water activity data gave an indication of the concentration ranges in which the sodium aluminate solution exists mainly as I) NaOH + monomeric Al(OH)4-and II) NaOH + dimeric Al2O(OH)62-ions.
The water activity at low aluminium concentrations showed a smaller, almost linear, increase. In case smaller mole ratios (greater aluminium concentrations) a greater increase of water activity occurred leading to a steeper straight line.The change in water activity can be described - depending on the total electrolyte concentration - by assuming the presence of Al(OH)4-and NaOH in the solution of smaller aluminium concentrations (1 -4 M/dm3) and NaOH and dimer Al2O(OH)62-complex aluminate ions in systems of higher aluminium concentrations (2 -7 M/dm3) under alkaline conditions.
Description of key information
Aluminium is the most abundant metal in the lithosphere, and is characterized by a complex biogeochemical cycle (Driscoll and Postek 1996; Exley, 2003). Aluminium can participate in hydrolysis reactions, thereby forming a number of monomeric and polymeric Al-hydroxides and this process is highly dependent on pH. Under REACH (ECHA 2008, Chapter R.7B – Endpoint Specific Guidance), the term ‘Hydrolysis’ refers to the “Decomposition or degradation of a chemical by reaction with water”, and this is a function of pH (i. e., abiotic degradation). Aluminium persists in the environment irrespective of whatever chemical species form as a result of hydrolysis, although it may form insoluble aluminium hydroxides that precipitate out of solution. Characterization of aluminium in environmental media is typically based on total aluminium concentrations inclusive of all specific chemical forms or species. Since hydrolysis changes the chemical form but does not decompose aluminium and since characterization of total aluminium considers all chemical forms, the concept of degradation of aluminium by hydrolysis is not relevant in the consideration of its environmental fate.
Key value for chemical safety assessment
Additional information
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 results in precipitation of aluminium hydroxide.
Aluminum salts are used as coagulants and flocculants to cause fine materials that are suspended, soluble or both to agglomerate, for subsequent removal via sedimentation and filtration. As part of this agglomeration or coagulation process, most of the aluminum associated with the added aluminum salt hydrolyses to aluminum hydroxide, which precipitates and becomes part of the floc structure. As such, it makes up a part of the sludge generated by the treatment process. A small amount of the aluminum added may stay with the finished water in either colloidal particulate (Al(OH)3) or soluble form (e.g., AlOH2+, Al(OH)2+, Al(OH)3, Al(OH)4-), dictated by the conditions of the treatment process and in particular, the pH
Reaction mass of aluminium hydroxide and aluminium nitrate and aluminium sulphate decomposes to aluminium hydroxide when adds to water and can therefore not be considered as water soluble.
Zhao et al. (2009) investigated the effect of pH in the range of 4.0 to 6.4 on the aluminium chloride hydrolysis at low concentration level. As coagulant aluminium chloride was diluted with deionised water.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-Al10species) and these further to large polymeric species (Al11- Al21). At pH 5.8 metastable median and large polymers decomposed into small aluminum species and disaggregated into dimeric species. With pH 6.4 the majority of aluminum formed to Al(OH)3amorphous flocs. In alkaline solution, depending on the concentration of aluminate, the soluble aluminate ions, Al(OH)4 ‾ and Al2O(OH)62 -ions are considered to be the totally dominating species (Szabo et al. 1978).
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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