Dipraseodymium dizirconium heptaoxide

Oxidising properties

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

oxidising solids

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

17 July 2012 - 21 January 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

UN Manual of Tests and Criteria: Test O.1 (Test for oxidizing solids)

Deviations:

yes

Remarks:

see below

Principles of method if other than guideline:

The electrical resistance of the ignition wire used was 3.9 Ω/m, which is a deviation from the electrical resistance of 6.0 ± 0.5 Ω/m specified in the Method O.1. However, the material (Nickel/Chromium), length (30 cm) and diameter (0.6 mm) of the wire met the method specifications. In addition, the appropriate combination of current and voltage was used to ensure that the electrical power dissipation in the wire (150 ± 7 W) also met the method specifications. Therefore, as the physical parameters of the wire and the power dissipation (i.e. the heat applied to the test) met the method specifications, the deviation from the electrical resistance of the wire had no effect on the test.

GLP compliance:

yes (incl. QA statement)

Contact with:

powdered cellulose

Sample tested:

reference: 3:7 mixture potassium bromate + cellulose

Parameter:

mean burning time

Result:

98 s

Remarks on result:

other: The cone burned with a yellow flame producing sparks and grey smoke, leaving a grey/black residue.

Sample tested:

4:1 sample-to-cellulose ratio

Parameter:

mean burning time

Result:

374 s

Remarks on result:

other: The cone ignited with a yellow flame, grey smoke and some sparks. The flame extinguished but the cone continued to glow red. Some grey charred remains were observed.

Sample tested:

1:1 sample-to-cellulose ratio

Parameter:

mean burning time

Result:

676 s

Remarks on result:

other: The cone ignited with a large yellow flame and grey smoke. The flame extinguished but the cone continued to glow red. Some grey charred residues remained.

Table 1 Potassium Bromate and Cellulose Mixture (3:7 by Mass)

Test Number	Burning Time (seconds)	Observations
1	94	The cone burned with a yellow flame producing sparks and grey smoke, leaving a grey/black residue.
2	91	The cone burned with a yellow flame producing sparks and grey smoke, leaving a grey/black residue.
3	110	The cone burned with a yellow flame producing sparks and grey smoke, leaving a grey/black residue.
4	102	The cone burned with a yellow flame producing sparks and grey smoke, leaving a grey/black residue.
5	95	The cone burned with a yellow flame producing sparks and grey smoke, leaving a grey/black residue.

Mean burning time = 98 seconds

Room temperature: 20 - 21 °C

 

Table 2 Test Material and Cellulose Mixture (4:1 by Mass)

Test Number	Burning Time (seconds)	Observations
1	466	The cone ignited with a yellow flame, grey smoke and some sparks. The flame extinguished after 145 seconds but the cone continued to glow red. Some grey charred remains were observed.
2	361	The cone ignited with a yellow flame, grey smoke and some sparks. The flame extinguished after 134 seconds but the cone continued to glow red. Some grey charred remains were observed.
3	340	The cone ignited with a yellow flame, grey smoke and some sparks. The flame extinguished after 134 seconds but the cone continued to glow red. Some grey charred remains were observed.
4	383	The cone ignited with a yellow flame, grey smoke and some sparks. The flame extinguished after 155 seconds but the cone continued to glow red. Some grey charred remains were observed.
5	320	The cone ignited with a yellow flame, grey smoke and some sparks. The flame extinguished after 110 seconds but the cone continued to glow red. Some grey charred remains were observed.

Mean burning time = 374 seconds

Room temperature: 19 °C

 

Table 3 Test Material and Cellulose Mixture (1:1 by Mass)

Test Number	Burning Time (seconds)	Observations
1	565	The cone ignited with a large yellow flame and grey smoke. The flame extinguished after 278 seconds but the cone continued to glow red. Some grey charred residues remained.
2	619	The cone ignited with a large yellow flame and grey smoke. The flame extinguished after 266 seconds but the cone continued to glow red. Some grey charred residues remained.
3	622	The cone ignited with a large yellow flame and grey smoke. The flame extinguished after 246 seconds but the cone continued to glow red. Some grey charred residues remained.
4	637	The cone ignited with a large yellow flame and grey smoke. The flame extinguished after 287 seconds but the cone continued to glow red. Some grey charred residues remained.
5	936	The cone ignited with a large yellow flame and grey smoke. The flame extinguished after 257 seconds but the cone continued to glow red. Some grey charred residues remained.

Mean burning time = 676 seconds

Room temperature: 19 °C

 

Discussion

The ignition wire broke during each of the tests for the mixtures of test material and cellulose. Breaking of the ignition wire often occurs with test material and cellulose mixtures but this is not the case for the reference mixtures. Test O.1 states that if the wire breaks during the test, then the test should be repeated unless the wire breaking clearly does not affect the result. In each case that the wire broke, it was judged not to have affected the test.

 

As the mean burning times for the mixtures of test material and cellulose were greater than the mean burning time for the 3:7 (by mass) mixture of potassium bromate and cellulose, it was not necessary to determine the mean burning times for the faster burning reference mixtures.

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of this study, the test material has been determined not to be an oxidising solid and requires no classification in accordance with EU criteria.

Reference 2

Endpoint:

oxidising solids

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

Data available on the individual constituents of the substance were considered to conclude on the endpoint. For praseodymium(III,IV) oxide, an experimental study is available, which is used for read across. For zirconium dioxide no data are available on the endpoint, because there was no need for performing an experimental study (study waived, see further). The read across justification document is attached in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Specific details on test material used for the study:

Initially, this substance was considered as a reaction mass and named "reaction mass of praseodymium(III,IV) oxide and zirconium dioxide".
But after discussion with ECHA, it was stipulated that it is a substance and we had to change the name to "Dipraseodymium dizirconium heptaoxide".

So, in the different endpoints with studies, the sustance named "reaction mass of praseodymium(III,IV) oxide and zirconium dioxide" corresponds to the substance Dipraseodymium dizirconium heptaoxide. They are the same, the analytical dossier did not changed.

Parameter:

other: based on read-across

Remarks on result:

other: The reaction mass of praseodymium(III,IV) oxide and zirconium dioxide is not considered to exhibit oxidising properties.

Remarks:

This conclusion is based on two types of information. First, the results of an experimental study performed with praseodymium(III,IV) oxide according to the UN O1 guideline demonstrated that praseodymium(III,IV) oxide has no oxidising properties. Second, zirconium dioxide is concluded not to exhibit oxidising properties either, based on the fact that it is a stable inorganic oxide with zirconium in its highest oxidation state (i.e. +IV) and is therefore not sensitive to oxygen release. This is confirmed by the release of energy when zirconium is oxidised (delta h298/0 (Zr to ZrO2) = -549 KJ/mol) and by the limited amount of hydrogen which is consumed by pure zirconium dioxide at high temperature (1200 K) (Barin, I., Knacke, O. Thermodynamic Properties of Inorganic Substances, Springer-Verlag, Berlin, Heidelberg, New York, 1973). Furthermore, experience in the day-to-day handling and use of the substance shows no oxidising potential. It should be noted that the redox properties of zirconium dioxide in the use of catalysts is due to the mobility of oxygen in the network of the catalytic material (Ramamoorthy, R., Sundararaman, S., Ramasamy, S. Solid state ionics, 123 (1999) p.271). An example being its use as a doping compound in oxygen storage materials used as catalysts in the automotive industry. Based on this information, the reaction mass of these two oxides can safely be concluded not to exhibit oxidising properties either.

Description of key information

There is no experimental data available for the endpoint on oxidising properties for dipraseodymium dizirconium heptaoxide. However, based on a weight of evidence approach including information available for the individual constituents of the substance, it can be concluded that the substance dipraseodymium dizirconium heptaoxide does not exhibit oxidizing properties

Key value for chemical safety assessment

Oxidising properties:

non oxidising

Additional information

1. Information on praseodymium(III,IV) oxide

Under the conditions of a UN O.1 guideline study (White, 2013; Klimisch 1), praseodymium(III,IV) oxide has been determined not to be an oxidising solid and requires no classification in accordance with EU criteria.

2. Information on zirconium dioxide

Zirconium dioxide being a stable inorganic oxide with zirconium in its highest oxidation state (i.e. +IV), is not sensitive to oxygen release. Moreover, experience in the day-to-day handling and use of the substance also confirms that it does not exhibit any oxidising potential.  

3. Conclusion on the substance dipraseodymium dizirconium heptaoxide

Since both oxides of the substance were demonstrated/concluded not to exhibit oxidising properties, it can be safely concluded that the substance of dipraseodymium dizirconium heptaoxide is not oxidising either.

Justification for classification or non-classification

Based on information available for its individual constituents, which do not exhibit oxidising properties, the substance dipraseodymium dizirconium heptaoxide was concluded not to exhibit oxidising properties either and therefore does not need to be classified under the CLP regulation.