Registration Dossier
Registration Dossier
Data platform availability banner - registered substances factsheets
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Diss Factsheets
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 231-545-4 | CAS number: 7631-86-9
- 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
Particle size distribution (Granulometry)
Administrative data
Link to relevant study record(s)
- Endpoint:
- particle size distribution (granulometry)
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2016-12-13
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- test procedure in accordance with national standard methods
- Qualifier:
- according to guideline
- Guideline:
- ISO 13320 (Particle size analysis - Laser diffraction methods)
- GLP compliance:
- yes
- Other quality assurance:
- ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
- Type of method:
- Laser scattering/diffraction
- Type of particle tested:
- agglomerate
- Type of distribution:
- volumetric distribution
- Specific details on test material used for the study:
- Name of product: AEROSIL® OX 50
EC number: 231-545-4
CAS no.: 112945-52-5
LOT: 155111045 / UB 862812 - Key result
- Percentile:
- D50
- Mean:
- 0.33 µm
- St. dev.:
- 0.122
- Conclusions:
- AEROSIL OX 50 has a D50 value of 0.33 µm using the method ISO 13320 via laser diffraction and based on a volumetric distribution
- Endpoint:
- particle size distribution (granulometry)
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2001
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- test procedure in accordance with national standard methods
- Qualifier:
- according to guideline
- Guideline:
- ISO 13320 (Particle size analysis - Laser diffraction methods)
- GLP compliance:
- yes
- Other quality assurance:
- ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
- Type of method:
- Laser scattering/diffraction
- Remarks:
- GRADIS
- Type of particle tested:
- agglomerate
- Type of distribution:
- volumetric distribution
- Key result
- Percentile:
- D50
- Mean:
- 680 µm
- St. dev.:
- 9.85
- Conclusions:
- HDK V15A has a D50 value of 680 µm using the method ISO 13320 via laser diffraction and based on a volumetric distribution
Referenceopen allclose all
Description of key information
Low end D50 value is 0.33 µm for Aerosil OX 50, a pyrogenic form of SAS
High end D50 value is 680 µm for HDK V15A, also a pyrogenic form of SAS.
Similar to the BET, density also these PSD values (which belong here to agglomerates) represent an overall range of the various SAS products.
Additional information
Expert-Statement
Provided by Dr. Juergen Nolde
Synthetic Amorphous Silica (SAS)
Particle Size Distribution
Constituent Particles/Aggregates/Agglomerates
The SAS particle size structure of SAS for the dry forms (silica gel, precipitated and pyrogenic SAS) have to be distinguished into three bottom up particular systems constituent particles, aggregates and agglomerates while colloidal silica is a monodisperse system in rare cases poly-disperse consisting of the constituent particles only.
Typical ranges for the SAS particular systems:
· Constituent (primary) particles:
Size range 1 to 100 nm, with mostly spherical form. The constituent particles size can be influenced to a certain extent by the product / process conditions
· Aggregates:
Size range >100 nm to 3 to 5 mm, depending on the form of SAS. There are chemical bonds between the primary particles, they are fused together and have sintering necks. Unnatural high forces are needed to break them.
Silica Gel typically forms very large aggregates due to manufacturing process in which sodium silicate solution and the diluted mineral acid are forming a complete solid gel, which can develop depending on the aging time cross-links and through Oswald rippling very strong chemical bindings between the constituent particles.
Precipitated and pyrogenic SAS are forming smaller aggregates, typically between >100 nm to several even low two digit micrometers.
Colloidal SAS is either monodisperse or in rare cases polydisperse. The spherical monodisperse particles or the very small aggregates consisting of a few spherical particles only are typically below 100 nm and thus fall under the definition of a nanoparticle. Colloidal SAS grades are only stable in a solvent, typically water, and once dried the particles formed cannot be re-dispersed forming a comparable product in the meaning of particle size distribution.
· Dry powders typically form agglomerates while forming large loose structures of aggregates, with van der Waals and H-bridges bonds between the aggregate surfaces, which can be easily destroyed towards the forming aggregates by inducing low shear forces. Typical agglomerate size of SAS powders can reach several hundred micrometers. Large silica gel particles show no tendency to form agglomerates.
Major difference between the aggregates and agglomerates is the amount of energy needed to destroy them into smaller particular units. Larger aggregates are not reintroduced while powders in dry stage always form agglomerates i.e. while filled into packaging or during transport.
Typical particle size distribution on commercial SAS grades is provided on mass based. For commercially relevant are the d10, d50 and d90 values. The mass based particle size distribution is measured through standard industrial particle size measurement either in suspension or in air. The measurements are based on ISO standards, which have been adopted and modified by the producers of SAS within in-house standard operating procedures. Hence, in-house measurements and even round robin measurements between different independent analytical laborites and industry on the same samples show a certain variation of the results. These variations depending on the sample preparation, the instrument and software used for transferring the signals into particle size and counting.
Agglomerate and in case of silica gels aggregate size, which is typically measured for SAS products, cannot be sued as a distinguishing parameter to cluster SAS grades, as they are widely overlapping and application driven. In principle the same material can be produced in different aggregates and agglomerates sizes to a certain extend by i.e. milling processes.
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.