Registration Dossier

Environmental fate & pathways

Adsorption / desorption

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Administrative data

Endpoint:
adsorption / desorption
Remarks:
adsorption/desorption
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
In aqueous medium, particularly in the environmentally relevant pH range, target substance titanium oxide sulphate is is rapidly converted to titanium dioxide via immediate hyxdrolysis reaction. Therefore adsorption/desorption testing of titanium oxide sulphate itself is technically not feasible. Thus the elaborations may be based on the general assessment of all titanium species being chemically stable in the environment (such as titanium dioxide). Based on this a read-across from supporting substances shall be proposed, by using stable, final hydrolysis product TiO2 as test surrogate. Furthermore, sulphuric acid is being formed as the other final hydrolysis product of titanium oxide sulphate, however this substance seems not relevant for assessment, as pH effects are to be excluded from assessment, and in its neutralised form as sulphate high natural background concentrations are common. No guideline study, but according to current scientific standards and well described.

Data source

Reference
Reference Type:
publication
Title:
Solid-water partitioning of elements in Czech freshwaters
Author:
Veselý J, Majer V, Kučera J, Havránek V
Year:
2001
Bibliographic source:
DOI: 10.1016/S0883-2927(00)00041-X, Applied Geochemistry 16:437-50

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Partitioning between suspended matter and water was studied by measuring Ti concentrations in solution and in corresponding suspended matter.
GLP compliance:
not specified
Type of method:
other:
Media:
other: Suspended solids

Test material

Constituent 1
Reference substance name:
Titanium
EC Number:
231-142-3
EC Name:
Titanium
Cas Number:
7440-32-6
IUPAC Name:
titanium(2+)
Details on test material:
Total and dissolved elemental Ti concentration measured in water samples collected from Czech rivers, no information on speciation
- Molecular formula (as other than submission substance): Ti
- Molecular weight (as other than submission substance): 47.900 g/mol
- Smiles notation (as other than submission substance): [Ti]
- InChl (as other than submission substance): InChI=1/Ti
- Structural formula attached as image file (as other than submission substance):Ti
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
JUSTIFICATION FOR READ ACROSS
In aqueous medium, particularly in the environmentally relevant pH range, target substance titanium oxide sulphate is is rapidly converted to titanium dioxide via immediate hyxdrolysis reaction. Therefore adsorption/desorption testing of titanium oxide sulphate itself is technically not feasible. Thus the elaborations may be based on the general assessment of all titanium species being chemically stable in the environment (such as titanium dioxide). Based on this a read-across from supporting substances shall be proposed, by using stable, final hydrolysis product TiO2 as test surrogate. Furthermore, sulphuric acid is being formed as the other final hydrolysis product of titanium oxide sulphate, however this substance seems not relevant for assessment, as pH effects are to be excluded from assessment, and in its neutralised form as sulphate high natural background concentrations are common.
Radiolabelling:
no

Study design

Batch equilibrium or other method

Analytical monitoring:
yes
Details on sampling:
Filtered and unfiltered water samples were collected under stable hydrological conditions. A volume of 200 mL of river water was generally filtered and another 100 mL were used for analysis.
Filtration through perforated polycarbonate filters was done in the field immediately after collection of river water samples. Samples were cooled and transported to the laboratory.
Unfiltered samples were acidified by adding 1 mL of HNO3 1:1 purified by sub-boiling distillation on the day of collection, to attain a pH of about 1.5.
The vessels were cleaned with 10% HNO3 for at least 2 days.
Filters were first boiled with distilled water acidified by HNO3 for 10 min before use, dried at 105°C, weighed and transported to the field in glass Petri dishes. A volume of 200 mL of river water was generally filtered and another 100 mL were used for analysis. A total of 155 filters were dried at 105°C, weighed in the laboratory, and the SPM deposited on them was analysed by particle induced X- ray emission (PIXE) and neutron activation analysis (NAA). The values of Kd were calculated by dividing the total concentration of the element in SPM (obtained by NAA or PIXE) by its concentration in filtered water.

Results and discussion

Partition coefficients
Phase system:
solids-water in suspended matter
Type:
log Kp
Value:
2.36 L/kg
Remarks on result:
other: median for samples from 54 rivers in 119 localities

Applicant's summary and conclusion

Validity criteria fulfilled:
not applicable
Conclusions:
For Ti-species sampled from 54 rivers in 119 localities, the median log Kp/Kd for suspended matter is 2.36 L/kg dw.
Executive summary:

Partitioning between suspended matter and water was studied by measuring Ti concentrations in solution and in corresponding suspended matter. Water samples were collected under stable hydrological conditions from 54 rivers in 119 localities (Czech freshwaters). Samples were being analyses via ICP-MS. For Ti-specis the median log Kp/Kd for suspended matter is 2.36 L/kg dw.