Pentanickel octahydroxide carbonate

Additional information on environmental fate and behaviour

Administrative data

Endpoint:

additional information on environmental fate and behaviour

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD 203 Transformation/dissolution Protocol (OECD, 2001) (Skeaff and Hardy, 2003a)

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

pentanickel dicarbonate hexahydroxide

Cas Number:

12122-15-5

Molecular formula:

C2H6Ni5O12

IUPAC Name:

pentanickel dicarbonate hexahydroxide

Results and discussion

Any other information on results incl. tables

Among the five screening tests at pH 6, the average value of Ni(aq) was 34.5 ± 10.7 mg/L while the maximum and minimum average values were 45.1 and 22.1 mg/L, respectively. The higher end of this range approaches the calculated concentration of 51.9 mg/L for the complete dissolution of pure NiCO3. The variability among the five flasks, expressed as a percentage of the standard deviation divided by the average value of Ni(aq), was 28%. This variability exceeded the anticipated between-vessel variation of 20%, possibly due to the occurrence in the flasks of agglomeration of the powder or its lack of consistent wettability, leading to lower values of Ni(aq). However, within each flask, the variability of the replicate analyses, expressed as a percentage of the standard deviation divided by the average value of Ni(aq), was less than 3%. The low standard deviation for each separate flask provides

confidence in the results of the ICP-MS method of analysis.

Among the five screening tests at pH 8, the average value of Ni(aq) was about 7 mg/L, with a standard deviation that amounted to 21% of the average, which is close to the anticipated among-flask variability of 20%. Within each test, the standard deviation was about 2% or less of the average value of Ni(aq). In tests 1, 2 and 3, the average values of Ni(aq) approach the calculated concentration of 6.9 mg/L. However, in tests 3 and 5, the average values of Ni(aq) are greater than the calculated concentration.

In transformation screening tests using the Draft OECD T/D Protocol for measuring the rate and extent of the transformation of metals and sparingly soluble inorganic compounds to bioavailable species, nickel carbonate hydroxide powder releases averages of about 7 ± 1.5 and 35 ± 11 mg/L of Ni(aq) at pH 8 and 6 in the aqueous media OECD 203 and dilute 10:1 OECD 203,

respectively. Given the amount of nickel released in the screening test, no further T/D P testing was conducted.

Applicant's summary and conclusion

Executive summary:

We have applied the 24-hour screening test for metal compounds of the Draft OECD

Transformation/Dissolution (T/D) Protocol to nickel carbonate hydroxide powder. The T/D Protocol is

intended to measure the rate and extent of the transformation of metals and sparingly soluble inorganic

metal compounds to the bioavailable form. The transformation data, when compared to existing

ecotoxicity data, can be used in the hazard classification of the substance under consideration.

The screening tests at pH 6 show that, after 24 hours of agitation in dilute 10:1 OECD 203

medium, the nickel carbonate hydroxide powder releases total dissolved nickel concentrations in the range

of about 22 and 46 mg/L. At pH 8, the concentrations of total dissolved nickel ranged between 5.5 and

9.3 mg/L in the regular OECD 203 medium. Given the relatively high levels of dissolved nickel obtained in

the screening test, the seven-day and 28-day transformation tests provided for in the Draft T/D Protocol

were not conducted.

The specific surface area of the nickel carbonate hydroxide powder as measured by a nitrogen

adsorption-desorption technique was 199 m2/g. Thus the relatively high measured specific surface area of

the nickel carbonate hydroxide powder may be a factor in its reactivity in the aqueous media.