Registration Dossier
Registration Dossier
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EC number: 257-098-5 | CAS number: 51274-00-1 This substance is identified in the Colour Index by Colour Index Constitution Number, C.I. 77492.
Endpoint summary
Administrative data
Description of key information
Iron hydroxide oxide yellow is an inorganic, yellow christaline solid and considered as nanomaterial.
Iron hydroxide oxide yellow has a very low water solubility ~1-2µg/L after 25 days at pH6-7.
No melting point due to modification at 160°C (water is released on heating)
Relative density: 4.26
Additional information
Information on nanoform-specific physico-chemical properties of iron hydroxide oxide yellow:
- Specific area: It is reported that the surface areas of both natural and synthetic goethites range from ca. 8 to 200 m²/g. XRD line broadening techniques indicate that soil goethites have surface areas of from 20 to 200 m²/g. On the other hand, massive (museum) specimens may consist of mm sized crystals with surface areas well below 1 m²/g.
- Zeta Potential: The zeta potential is not a characteristic of the metal oxide or the particle consisting
of iron oxide in itself.
- Porosity: N2 adsorption isotherms for samples with acicular crystals were type II and gave no indication of there being meso- or microporosity. No evidence of porosity was found for 15 synthetic goethites grown from both Fe(II) and Fe(III) solutions (pH 6 -12).
- Surface Chemistry: The surface chemistry of iron oxide and ferrite pigments is determined by the oxygen present on the surface and their hydroxylation. So no feasible surface activity is observed beside the typical adsorption of species.
- Agglomeration/Aggregation: Like most particulate substances iron hydroxide oxide is present in a highly agglomerated and aggregated form only. These are to be separated in the dispersion process.
- Crystalline Phase: FeOOH is used to the vast majority in their α-modification. A small part of γ-FeOOH is also used. While distinguishable by X-ray-diffraction the α- and γ-modification are very similar in physical and chemical characteristics. No difference is to be expected in toxicological and eco-toxicological aspects.
- Photocatalytic Activity: No known photocatalytic activities of iron oxide and ferrite pigments.
- Pour Density: Result given as tamped density: 0.2 - 0.6 g/ml
- Aspect Ratio: Median aspect ratio 2.1 +/- 1.2
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