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Physical & Chemical properties

Water solubility

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Reference
Endpoint:
transformation / dissolution of metals and inorganic metal compounds
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016-09-07 to 2017-03-02
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Series on Testing and Assessment No. 29 (23-Jul-2001): Guidance document on transformation/dissolution of metals and metal compounds in aqueous media
Deviations:
no
GLP compliance:
no
Type of method:
flask method
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Element analysed:
Zirconium
Loading of aqueous phase:
1 mg/L
Incubation duration:
7 d
Test conditions:
pH 6
Remarks on result:
not determinable because of methodological limitations
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Element analysed:
Zirconium
Loading of aqueous phase:
1 mg/L
Incubation duration:
28 d
Test conditions:
pH 6
Remarks on result:
not determinable because of methodological limitations
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Element analysed:
Zirconium
Loading of aqueous phase:
10 mg/L
Incubation duration:
7 d
Test conditions:
pH 6
Remarks on result:
not determinable because of methodological limitations
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Element analysed:
Zirconium
Loading of aqueous phase:
100 mg/L
Incubation duration:
7 d
Test conditions:
pH 6
Remarks on result:
not determinable because of methodological limitations

A screening test to determine the pH of maximum dissolution between 6, 7 and 8 was performed for the zirconium compound. The results correspond to the metal release after 24 hours of incubation at 22 °C with 200 rpm agitation rate and a mass loading of 100 mg/L. The data of metals released from the transformation / dissolution assays, is shown with the blanks information on the top half of the table and the samples information in the bottom half of the table. Mean: is the average metal release µg/L; St. Dev.: Standard deviation. CV, %: Coefficient of variation (ratio of Standard deviation respect to the mean concentration, in percentage). BDL: below detection limit.

Zirconium, µg/L
Screening pH 6
  Time [h] T [°C] O2[mg/L] pH Mean SD CV [%]
Blanks 0 21.9 6.6 6.03 BDL - -
24 22.5 6.6 6.11 BDL - -
ZrSi2 0 21.9 6.6 6.03 BDL - -
24 23.0 6.7 6.09 0.29 0.06 21
Screening pH 7
  Time [h] T [°C] O2[mg/L] pH Mean SD CV [%]
Blanks 0 21.0 7.1 7.08 BDL - -
24 21.7 7.0 7.05 BDL - -
 ZrSi2 0 21.0 7.1 7.08 BDL - -
24 21.4 7.2 7.05 0.063 0.035 55
Screening pH 8
  Time [h] T [°C] O2[mg/L] pH Mean SD CV [%]
Blanks 0 21.2 7.0 7.90 BDL - -
24 21.2 7.1 7.91 BDL - -
 ZrSi2 0 21.2 7.0 7.90 BDL - -
24 21.1 7.5 7.93 0.04 0.01 20

Very low solubility values were measured in the screening test for zirconium disilicide. In the case of pH 6, blanks measurements were around the method detection limit (MDL = 0.04 µg/L) and below the practical quantitation level (PQL = 0.23 µg/L).

Conclusions:
The results showed that zirconium disilicide can be considered as insoluble (< 0.1 mg/L) in aqueous solution in this study according to OECD 29.
Executive summary:

A transformation/dissolution (T/D) test, according to OECD 29, was carried out to study the potential of zirconium disilicide to release metal to the environment.

A 24 hour screening test to determine the pH of maximum zirconium release was performed at pH 6, 7 and 8 with a loading rate of 100 mg/L. The pH screening test showed zirconium releases of 0.29 ± 0.06 µg Zr/L at pH 6, while the mean release of Zr at pH 7 and 8 was 0.063 ± 0.035 respectively 0.04 ± 0.01 μg Zr/L.

The full T/D test was conducted at pH 6. The acute endpoint (7 days), was performed at sample loadings of 1, 10 and 100 mg/L; the chronic endpoint was determined from the extension of the 1 mg/L loading test to 28 days. The results of the study documented zirconium release measurements as follows:

- 1 mg/L loading after 7 days: below detection limit

- 1 mg/L loading after 28 days: below detection limit          

- 10 mg/L loading after 7 days: below detection limit

- 100 mg/L loading after 7 days: below detection limit

Therefore, zirconium disilicide is considered to be highly insoluble in water.

Description of key information

A transformation/dissolution (T/D) test, was carried out according to OECD Series on Testing and Assessment No 29 (2001): Transformation dissolution of metals and metal compounds in aqueous media, to study the potential of zirconium disilicide to release metal ions to the environment showing that the test substance is highly insoluble.

Key value for chemical safety assessment

Additional information

A transformation/dissolution (T/D) test, according to OECD 29, was carried out to study the potential of zirconium disilicide to release metal to the environment.

A 24 hour screening test to determine the pH of maximum zirconium release was performed at pH 6, 7 and 8 with a loading rate of 100 mg/L. The pH screening test showed zirconium releases of 0.29 ± 0.06 µg Zr/L at pH 6, while the mean release of Zr at pH 7 and 8 was 0.063 ± 0.035 respectively 0.04 ± 0.01 μg Zr/L.

The full T/D test was conducted at pH 6. The acute endpoint (7 days), was performed at sample loadings of 1,10 and 100 mg/L; the chronic endpoint was determined from the extension of the 1 mg/L loading test to 28 days. The results of the study documented zirconium release measurements as follows:

- 1 mg/L loading after 7 days: below detection limit

- 1 mg/L loading after 28 days: below detection limit          

- 10 mg/L loading after 7 days: below detection limit

- 100 mg/L loading after 7 days: below detection limit

Therefore, zirconium disilicide is considered to be highly insoluble in water.