Registration Dossier
Registration Dossier
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EC number: 233-477-0 | CAS number: 10193-36-9
Hydrolysis
Administrative data
- Endpoint:
- hydrolysis
- Type of information:
- other: Hand Book Data
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
Data source
Reference
- Reference Type:
- review article or handbook
- Title:
- Unnamed
- Year:
- 2 004
- Report date:
- 2004
Materials and methods
- Principles of method if other than guideline:
- hand book data
- GLP compliance:
- no
Test material
- Reference substance name:
- Silicon dioxide
- EC Number:
- 231-545-4
- EC Name:
- Silicon dioxide
- Cas Number:
- 7631-86-9
- Molecular formula:
- O2Si
- IUPAC Name:
- Silicon dioxide
- Test material form:
- solid
Constituent 1
Results and discussion
- Preliminary study:
- The basic consideration is that silica dissolves according to : SiO2 + H2O = Si(OH)4. At low concentrations most species are present as monomers, at higher concentrations polymerisation will occur.
Most soluble silicates are in the form:
M2O . mSiO2 . nH2O
where M = alkali metal, predominantly Na, but also K. The index m (molar ratio) ranges between 0.5 - 4, most commonly m = 3.3. Stability depends to a large extent on pH, above pH 10.6 the solutions are chemically stable. The increase of
ionic strength accelerates nucleation and deposition and decreases the SiO2 solubility. Coating of surfaces by organic matter may hamper dissolution, but at the same time Si(OH)4 may form complexes with organic matter, a process
which favours dissolution. - Transformation products:
- not specified
Dissipation DT50 of parent compound
- Key result
- Remarks on result:
- hydrolytically stable based on preliminary test
Any other information on results incl. tables
The basic consideration is that silica dissolves according to : SiO2 + H2O = Si(OH)4. At low concentrations most species are present as monomers, at higher concentrations polymerisation will occur.
Most soluble silicates are in the form:
M2O . mSiO2 . nH2O
where M = alkali metal, predominantly Na, but also K. The index m (molar ratio) ranges between 0.5 - 4, most commonly m = 3.3. Stability depends to a large extent on pH, above pH 10.6 the solutions are chemically stable. The increase of
ionic strength accelerates nucleation and deposition and decreases the SiO2 solubility. Coating of surfaces by organic matter may hamper dissolution, but at the same time Si(OH)4 may form complexes with organic matter, a process
which favours dissolution.
Applicant's summary and conclusion
- Conclusions:
- The basic consideration is that silica dissolves according to : SiO2 + H2O = Si(OH)4. At low concentrations most species are present as monomers, at higher concentrations polymerisation will occur.
Most soluble silicates are in the form:
M2O . mSiO2 . nH2O
where M = alkali metal, predominantly Na, but also K. The index m (molar ratio) ranges between 0.5 - 4, most commonly m = 3.3. Stability depends to a large extent on pH, above pH 10.6 the solutions are chemically stable. The increase of
ionic strength accelerates nucleation and deposition and decreases the SiO2 solubility. Coating of surfaces by organic matter may hamper dissolution, but at the same time Si(OH)4 may form complexes with organic matter, a process
which favours dissolution.
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