Divanadium pentaoxide

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-02-02 to 2010-02-10

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

July 27th, 1995

Deviations:

yes

Remarks:

See "Principles of method if other than guideline"

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

May 31st, 2008

Deviations:

yes

Remarks:

See "Principles of method if other than guideline"

Principles of method if other than guideline:

Two deviations to the OECD/EC protocol:
- The study was performed under exclusion of atmospheric oxygen and carbon dioxide under inert gas (e.g. argon).
- The guideline describes the use of one individual flask for each sampling resulting in one measurement per sampling. However, two vessels with solutions containing the test item and two method blanks was set up in a parallel design at 20.0 ± 1.0°C, and the solution in each vessel was sampled several times instead of sampling the solution of a different vessel at each time point. This modification helps to avoid weighing errors, enables repeated sampling from two vessels and therefore leads to more results from two individual flasks for each different time point. The design further helps to confirm individual measurement results, to point out potential issues at an early stage and to obtain more accurate test results.

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2007-03-21

Type of method:

flask method

Water solubility:

515 mg/L

Conc. based on:

element (dissolved fraction)

Remarks:

equilibrium after 3 days of stirring

Loading of aqueous phase:

40 g/L

Temp.:

20 °C

pH:

2.7

Remarks on result:

other:

Remarks:

under exclusion of CO2 and O2 under argon gas

Key result

Water solubility:

920 mg/L

Conc. based on:

test mat. (dissolved fraction)

Remarks:

equilibrium after 3 days of stirring

Loading of aqueous phase:

40 g/L

Temp.:

20 °C

pH:

2.7

Remarks on result:

other: under exclusion of CO2 and O2 under argon gas

Details on results:

Under the conditions of this test (under exclusion of CO2 and O2 under argon gas; flask method; loading of 40g/L), the water solubility of divanadium pentaoxide at 20.0 ± 0.5°C was determined at 0.92 ± 0.02 g/L (dissolved V measured by ICP-OES after test day 1, 2, 3 and 6, separated by filtration (0.2 µm) from undissolved test material). Equilibrium was reached after 3 days. The resulting solution pH was measured to be ~ 2.7.
During the study, a yellow-orange precipitate of possibly divanadium pentaoxide was observed. The supernatant was of a yellow colour. After filtration, the solution was still coloured yellow but clear. In order to verify this, the turbidity was measured in the filtrates.
After adding the test substance, the pHs of all loaded test media decreased below 2.7. The study was conducted under inert gas (Argon) as good as possible. The O2 levels at sampling times were low (0.80 - 2.67 ppm). The temperature in the test vessels ranged from 19.5 – 20.5 °C as recommended in the OECD guidance (20.0 ± 0.5 °C), except blank 1 at the sampling after 48h (20.7 °C).

Conclusions:

Under the conditions of this test (under exclusion of CO2 and O2 under argon gas; flask method; loading of 40g/L, tested in douplicate), the water solubility of divanadium pentaoxide at 20.0 ± 0.5°C was determined at 0.92 ± 0.02 g/L (dissolved V measured by ICP-OES after test day 1, 2, 3 and 6, separated by filtration (0.2 µm) from undissolved test material). After 3 days of testing equilibrium was reached. The resulting solution pH was measured to be ~ 2.7. Hence, divanadium pentaoxide may considered as moderately soluble (100-1000 mg/L).

Description of key information

The water solubility of divanadium pentaoxide under O₂ and CO₂ exclusion, at a loading of approx. 40 g/L was determined with 0.92 ± 0.02 g/L at 20 °C (pH 2.7) in acordance with OECD TG 105. Equilibrium was reached after 3 days, and the dissolved vanadium concentration was measured by ICP-OES at sampling days 1, 2, 3 and 6.

 

In the transformation/dissolution test according to OECD Series 29, a nearly complete dissolution of divanadium pentaoxide was observed at a loading of 1 mg/L and pH 6 and pH 8 at 21°C, mainly pentavalent vanadium species were measured.

Key value for chemical safety assessment

Water solubility:

0.92 g/L

at the temperature of:

20 °C