Zirconium dihydride

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

key study

Study period:

- Start of the test period: 02.08.2016 - End of the test period: 17.11.2016

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

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:

yes

Principles of method if other than guideline:

1) Preliminary test
In order to determine an appropriate pH of the dissolution medium a preliminary test according to paragraph 26 of OECD 29 was performed. 100 ml glass bottles were filled with 50 ml of aqueous buffer solution at pH 5,5, pH 7 and pH 8,5, each in duplicate. A sample amount of approx. 5 mg was weighed under Argon atmosphere and suspended in the buffer solution at 23 °C. After 2 days a filtered aliquot of each bottle was analyzed for Zirconium content by ICP-OES according to EN ISO 11885.
2) Full test (7 and 28 days)
- For the full test according to paragraphs 34 and 35 of OECD 29 a buffered aqueous solution with pH 6 was chosen in order to maximize the potential of dissolution. 600 ml glass bottles were filled with 500 ml of the buffer medium. After a half-hour equilibrium phase pH, temperature and dissolved oxygen concentration of each vessel were measured. Duplicate aliquots of each vessel were taken in order to determine the background metal concentration of the medium by ICP-OES according to EN ISO 11885.
- Three different loadings of the test substance were prepared (1 mg/l, 10 mg/l, 100 mg/l), each in triplicate. An appropriate sample amount was weighed under Argon atmosphere into the buffer. The closed glass bottles were gently moved in a temperature controlled cabinet in the dark at 23 °C for the entire test duration of 29 days.
- At established time intervals the bottles were visually inspected and duplicate sample aliquots were taken for quantitative analysis of the Zirconium concentration. In order to prevent sample particles from being transferred to the analytical process all aliquots were filtered through 0,2 μm regenerated Cellulose membrane syringe filter. For each aliquot temperature, pH and dissolved oxygen were determined as well.
- The agitation period startet on 16.08.2016, 12:30. Sampling at the short term endpoint was on 23.08.2016, 13:30. Sampling at the long term endpoint was on 14.09.2016, 11:30. Undissolved substance was still visible at the bottom of each bottle at the end of the test period.

Note:
- pH was determined by an electronic pH-meter, device Metrohm 781
- Dissolved oxygen concentration was determined according to DIN EN 25813.

GLP compliance:

no

Other quality assurance:

ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)

Type of method:

other: See above

Specific details on test material used for the study:

Sample : Zirconium hydride G, Batch no. 73311
Appearance : Grey powder
Container : Metal can, 250 ml
ASG-ID : 2404379_002

Key result

Water solubility:

< 0.08 mg/L

Conc. based on:

element

Remarks:

Zirconium

Loading of aqueous phase:

1 mg/L

Incubation duration:

ca. 29 d

Temp.:

23 °C

pH:

5.8

Water solubility:

< 0.08 mg/L

Conc. based on:

element

Remarks:

Zirconium

Loading of aqueous phase:

10 mg/L

Incubation duration:

ca. 29 d

Temp.:

23 °C

pH:

5.8

Water solubility:

< 0.08 mg/L

Conc. based on:

element

Remarks:

Zirconium

Loading of aqueous phase:

100 mg/L

Incubation duration:

ca. 29 d

Temp.:

23 °C

pH:

5.8

Conclusions:

The water solubility of zirconium hydride (ZrH2) following the OECD guideline n°29: "transformation/dissolution of metals and metal compounds in aquaeous media" was found below the detection limit (<0.08 mgZr/L).
As a final conclusion of all data it can be stated that the test substance Zirconium hydride is insoluble in water.

Key value for chemical safety assessment

Water solubility:

0.08 mg/L

at the temperature of:

23 °C

Additional information

Zirconium hydride is insoluble in water. The values measured following the test guideline OECD n°29 was below the detection limit of the ICP-OES (0.08 mgZr/L)