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Water solubility

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Reference
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: In-house study performed according to OECD guidelines.
Qualifier:
according to guideline
Guideline:
OECD Guideline 105 (Water Solubility)
GLP compliance:
no
Type of method:
flask method
Water solubility:
0.074 mg/L
Temp.:
30 °C
Remarks on result:
other: The pH has not been measured during the test, as titanium diboride is not subject to hydrolysis (see chapter 5.1.2) and is known to be highly chemically inert.
Details on results:
Single results: 0.073 / 0.075 / 0.075 mg/L
Mean value: 0.074 mg/L
Standard deviation: 0.001 mg/L
RSD: 1.6 %
Conclusions:
Interpretation of results (migrated information): insoluble (< 0.1 mg/L)
The water solubility of titanium diboride can be regarded as being below 0.074 mg/L, as the measured value (soluble boron) is a sum of soluted boron oxide (B2O3 content in test item is 1.56%, see analytical results chapter 1.4) and very small titanium boride particles not separable by sedimentation methods.

It is technically impossible to measure the solubility of titanium diboride, defined as saturation concentration of TiB2 in water as there is no analytical method available to detect TiB2 in aqueous solutions. Furthermore, experience in handling and use of TiB2 show that TiB2 is highly insoluble in water. Pre-tests performed with the test material showed that the solubility of TiB2 is far below 1 mg/L. Practically, the concentration of TiB2 in 1 L of water could be reduced to 1 particle/L without complete dissolution of this particle. Against this background, the concentration of boron in aqueous extracts of 1 mg TiB2 in 1 L of water has been determined by ICP-MS and used to calculate a theoretical solubility of TiB2 in water. The calculated theoretical water solubility of TiB2 can be regarded to be below 0.074 mg/L. The real water solubility of TiB2 is far below this value as the measured boron concentration is a sum of solubilised boron oxide (resulting from the boron oxide passivation layer on particle surfaces; B2O3 content in test item is 1.56%, see analytical results chapter 1.4) and very small TiB2 particles not separable from the extract by sedimentation methods, which are detected as solubilised boron by ICP-MS.

Description of key information

Interpretation of results: insoluble (< 0.1 mg/L)
The water solubility of titanium diboride can be regarded as being below 0.074 mg/L, as the measured value (soluble boron) is a sum of soluted boron oxide (B2O3 content in test item is 1.56%, see analytical results chapter 1.4) and very small titanium boride particles not separable by sedimentation methods.

Key value for chemical safety assessment

Water solubility:
0.074 mg/L
at the temperature of:
30 °C

Additional information