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Water solubility

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Description of key information

The maximum solubility of tantalum carbide, determined in transformation/dissolution test, was 0.333 µg/L.

Key value for chemical safety assessment

Water solubility:
0.333 µg/L
at the temperature of:
21.5 °C

Additional information

The transformation/dissolution behaviour of tantalum carbide was determined in accordance with Guidance Document No. 29 from the OECD Series on Testing and Assessment.

Prior to the full test a screening over 24 h (agitation at 100 rpm, 21.5 ± 1.5 °C, loading of 100 mg/L) was conducted in test media at pH 6 and pH 8 in triplicate vessels and duplicate samples per vessel. After 24 h the dissolved tantalum concentrations were quantified by ICP-MS.

Based on the screening results, demonstrating maximised solubility at pH 6, the full test was performed in test media at a target pH of 6. Solutions for the full test (1, 10, and 100 mg/L, nominal) were sampled after 2 h, 6 h, 24 h, 96 h (4 d), 168 h (7 d). For the test with 1 mg/L additional samplings were performed after 336 h (14 d), 504 h (21 d) and 672 h (28 d). Solution pH, oxygen concentrations and total dissolved tantalum concentrations were measured. The test was performed in triplicate (three replicates per pH, sampled twice at each sampling point).

Maximum solubility in the definitive test was achieved at a nominal loading of 100 mg/L, with a saturated Ta concentration of 0.333 µg/L (21.5 °C, pH 8, after 7 days).