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EC number: 234-919-5 | CAS number: 12040-43-6
- 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
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- Jun. 4 - Nov. 18, 2019; experimental phase: Jun. 4 - 27, 2019
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 111 (Hydrolysis as a Function of pH)
- Version / remarks:
- 2004
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
- Version / remarks:
- 2008
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Specific details on test material used for the study:
- Name: Silicic acid, magnesium aluminium sodium salt
Batch no.: 201810LC007
Appearance: white fluffy powder
Composition: Sodium; Magnesium; Aluminium; Silica
Purity: >95%
Homogeneity: homogeneous
Specific surface area: 57.9 m²/g - Radiolabelling:
- no
- Analytical monitoring:
- yes
- Details on sampling:
- The same sample preparation was performed on day 0 and 5.
Before measurement of the solutions via ICP-OES for Si (blanks and test item solutions) tenfold dilution was performed: 0.5 mL of the solution were added to 4.5 mL water p.a. and measured via ICP-OES. - Buffers:
- Buffer-Solution, pH 4
Parameter Amount
CH3COOH, 2 M 80 mL
CH3COONa, 1 M 40 mL
Water p.a. ad. 1000 mL
Three replicates were prepared and combined; pH was measured as 4.02 (batch A20190603).
For batch A20190613 (used in the Tier 1), two replicates were prepared and combined; pH was measured as 4.0.
Buffer-Solution, pH 7
Batch A20190604:
Parameter Amount
KH2PO4 8.7085 g
Water p.a. 500 mL
NaOH, 2 M 14.9 mL
Water p.a. ad. 1000 mL
Three replicates were prepared and combined; pH was adjusted with 2 M NaOH to 7.04.
Batch A20190613 (used in the Tier 1):
Parameter Amount
KH2PO4 8.7089 g / 8.7079 g (for replicate 1 and 2)
Water p.a. 500 mL
NaOH, 2 M 14.9 mL
Water p.a. ad. 1000 mL
Two replicates were prepared and combined; pH was adjusted with 2 M NaOH to 7.00.
Buffer-Solution, pH 9
Batch A20190604:
Parameter Amount
H3BO3 3.093 g
KCl 3.729 g
Water p.a. 500 mL
NaOH, 2 M 10.75 mL
Water p.a. ad. 1000 mL
Three replicates were prepared and combined; pH was adjusted with 2 M NaOH to 9.00.
Batch A20190613 (used in the Tier 1):
Parameter Amount
H3BO3 3.0927 g / 3.0926 g (for replicate 1 and 2)
KCl 3.7298 g / 3.7294 g (for replicate 1 and 2)
Water p.a. 500 mL
NaOH, 2 M 10.75 mL
Water p.a. ad. 1000 mL
Two replicates were prepared and combined; pH was adjusted with 2 M NaOH to 9.03. - Estimation method (if used):
- The analytical determination of the test item was performed via measurement of Silicon (Si), Magnesium (Mg) and Aluminium (Al) via ICP-OES.
- Duration:
- 5 d
- pH:
- 4
- Temp.:
- 50 °C
- Initial conc. measured:
- 41.67 mg/L
- Remarks:
- silicon
- Duration:
- 5 d
- pH:
- 7
- Temp.:
- 50 °C
- Initial conc. measured:
- 46.35 mg/L
- Remarks:
- silicon
- Duration:
- 5 d
- pH:
- 9
- Temp.:
- 50 °C
- Initial conc. measured:
- 36.6 mg/L
- Remarks:
- silicon
- Duration:
- 5 d
- pH:
- 4
- Temp.:
- 50 °C
- Initial conc. measured:
- 384.7 mg/L
- Remarks:
- magnesium
- Duration:
- 5 d
- pH:
- 7
- Temp.:
- 50 °C
- Initial conc. measured:
- 20.21 mg/L
- Remarks:
- magnesium
- Duration:
- 5 d
- pH:
- 9
- Temp.:
- 50 °C
- Initial conc. measured:
- 3.948 mg/L
- Remarks:
- magnesium
- Number of replicates:
- 2 (+ blank controls)
- Positive controls:
- no
- Negative controls:
- yes
- Preliminary study:
- The test item was considered to be stable and no further examination was made.
s. below on detailed results - Transformation products:
- no
- % Recovery:
- > 100
- St. dev.:
- 0
- pH:
- 4
- Temp.:
- 50 °C
- Duration:
- 5 d
- Remarks on result:
- other: Si content
- % Recovery:
- 92.2
- St. dev.:
- 1.5
- pH:
- 7
- Temp.:
- 50 °C
- Duration:
- 5 d
- Remarks on result:
- other: Si content
- % Recovery:
- 93.4
- St. dev.:
- 0.5
- pH:
- 9
- Temp.:
- 50 °C
- Duration:
- 5 d
- Remarks on result:
- other: Si content
- % Recovery:
- 100
- St. dev.:
- 0.6
- pH:
- 4
- Temp.:
- 50 °C
- Duration:
- 5 d
- Remarks on result:
- other: Mg content
- % Recovery:
- 98.2
- St. dev.:
- 2.7
- pH:
- 7
- Temp.:
- 50 °C
- Duration:
- 5 d
- Remarks on result:
- other: Mg content
- % Recovery:
- 96
- St. dev.:
- 0.3
- pH:
- 9
- Temp.:
- 50 °C
- Duration:
- 5 d
- Remarks on result:
- other: Mg content
- Key result
- Temp.:
- 25 °C
- DT50:
- > 365 d
- Type:
- (pseudo-)first order (= half-life)
- Remarks on result:
- hydrolytically stable based on preliminary test
- Validity criteria fulfilled:
- yes
- Conclusions:
- The concentration of Al in pH 4, 7 and 9 buffer solutions lay below the LOQ of the respective method at each sampling point (< 0.05 mg/L in pH 4 and 9 solutions and < 0.02 mg/L in pH 7 solutions). Therefore, the calculation of the stability of Al in buffer solutions was not possible.
As the amount of Si and Mg after five days was more than 90 % of the amount at the start of the test, the test item was considered to be stable (following OECD, t(0.5) at 25 °C is then greater than 1 year), and no further examination was made.
Recovery rate based on solid content, reformation of inorganic salts (ICP-OES measured Si content):
pH=4: ca. 100 %; pH=7: 92.2 %; pH=9: 93.4 % - Executive summary:
This study was performed in order to determine the hydrolysis behaviour of Silicic acid, magnesium aluminium sodium salt and stability of dissolved test item in dependence of the pH.
Aqueous buffer solutions of different pH values (pH 4, 7 and 9) were treated with the test item and the filtrated test item solutions were incubated in the dark under controlled laboratory conditions (at constant temperature). After appropriate time intervals, buffer solutions were analysed for Silicon (Si), Magnesium (Mg) and Aluminium (Al) via ICP-OES. The concentration of Sodium (Na) was not determined as Sodium is present in all buffer solutions. Potentially available undissolved particles in the filtrated test item solution were measured using Tyndall device.
- Endpoint:
- hydrolysis
- Type of information:
- other: reference link
- Adequacy of study:
- other information
- Reason / purpose for cross-reference:
- read-across source
Referenceopen allclose all
The half saturated solutions with the nominal load 50 g/L in pH 4, 7 and 9 buffer solutions were measured for Si, Al and Mg on day 0 and after the storage of the test solutions at 49.7 – 50.2 °C for 5 days. The concentration of Al in pH 4, 7 and 9 buffer solutions was below the LOQ of the respective method at each sampling point (< 0.05 mg/L in pH 4 and 9 solutions and < 0.02 mg/L in pH 7 solutions). Therefore, the calculation of the stability of the test item in buffer solutions based on Al was not possible. All measurements lay below the LOD of the Tyndall device (< 3 mg/L particle concentration).
Recovery rate based on solid content reformation of inorganic salts (ICP-OES measured Si content): pH = 4: 102.9%; pH = 7: 92.2%, pH = 9: 93.4%. As the amount of Si and Mg after five days was more than 90% of the amount at the start of the test, the test item was considered to be stable (following OECD, t(0.5) at 25 °C is then greater than 1 year), and no further examination was made.
Description of key information
One study was performed in order to determine the hydrolysis behaviour of Silicic acid, magnesium aluminium sodium salt and stability of dissolved test item in dependence of the pH (Affolter, 2019, OECD 111):
The concentration of Al in pH 4, 7 and 9 buffer solutions lay below the LOQ of the respective method at each sampling point (< 0.05 mg/L in pH 4 and 9 solutions and < 0.02 mg/L in pH 7 solutions). Therefore, the calculation of the stability of Al in buffer solutions was not possible.
As the amount of Si and Mg after five days was more than 90 % of the amount at the start of the test, the test item was considered to be stable (following OECD, t(0.5) at 25 °C is then greater than 1 year), and no further examination was made.
Recovery rate based on solid content, reformation of inorganic salts (ICP-OES measured Si content):
pH=4: ca. 100 %; pH=7: 92.2 %; pH=9: 93.4 %
Key value for chemical safety assessment
Additional information
Silicic acid, aluminium magnesium sodium salt is an inorganic solid and moderately soluble in water. Due to its chemical nature and stability, hydrolysis is not expected.
However, ion exchange processes are possible depending on the surrounding environment to transfer the substance in another, as very limited, not quantifiable hydrolysis is involved in the dissolution of silicates in water. It is limited to a gel-layer surrounding the silicate particle in aqueous medium. This layer is in equilibrium with the outer aqueous phase and constitutes a diffusion barrier for ions and water.
Assuming that the dissolution products expressed as Si(OH)4, Mg(OH)2, NaOH and Al(OH)3, which is very reasonable, the total dissolution rate can be calculated to approx. 902 mg/L. (Affolter, 2020, OECD 105)
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