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Environmental fate & pathways

Additional information on environmental fate and behaviour

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Administrative data

Endpoint:
additional information on environmental fate and behaviour
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report date:
2013

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
An in vitro cytotoxicity study with the mouse macrophage cell line (RAW 264.7) was conducted using three not-treated nanoforms of carbon black with different constituent particle sizes and surface areas and three treated form generated by oxidising the treated forms. The purpose of the study was to evaluate whether there are differences in toxicity- based on differences in constituent particle sizes and surface areas. Another purpose of the study was to compare the not-treated nanoforms to the treated nanoforms. Pre test, chemical characteristic parameters were also determined for the samples used in the study: pH of the respective grades, measured as a slurry, Primary particle size, aggregate particle size, BET surface area and the agrregate size in cell culture media, measured by using dynamic light scattering on a Brookhaven Instrument BIC-90. The size is what is termed “effective diameter” by the testing lab. A generic description would be the “PCS average diameter” (PCS is photon correlation spectroscopy which is particular type of dynamic light scattering. The measurement was done after diluting the material to approx. 1 ug/ml and within 2 hours of sonication
GLP compliance:
yes (incl. QA statement)
Type of study / information:
hydrophobicity and pH of carbon black grades (not treated and treated)

Test material

Constituent 1
Chemical structure
Reference substance name:
Carbon black
EC Number:
215-609-9
EC Name:
Carbon black
Cas Number:
1333-86-4
Molecular formula:
C
IUPAC Name:
Carbon black
Test material form:
solid: nanoform, surface-treated
Specific details on test material used for the study:
CB1 is a low surface area not treated base black, CB2 is created by doing a nitric acid surface treatment of CB1. CB3 is a high surface area base not treated black, and CB4 is created by doing a nitric acid surface treatment of CB4. CB6 is a sulfanilic acid treated version of the low surface area not treated base black, CB5. CB 6 is not part of the regeistration, it data is not shown below.

Results and discussion

Any other information on results incl. tables

As evidenced from the values for their surface energy, CB1, CB3 and CB5, all, not treated base black were more hydrophobic and had lower surface energies than their acid treated counterparts. CB2, CB 4 respectively. The surface treated forms are however still hydrophobic

Table of chemical characteristics of tested grades

TNO ID

Description

 pH

Constituent Particle Size (nm) (a)

Aggregate Size (nm) (a)

 N2 Surface Area - BET (m2/g)

Hydrophobicity - Surface Energy (mJ/m2) 

Aggregate size in cell culture media (um) (d)

CB1

Not treated base black

9.25

20.58

89.82

84.1

13.9

6.0

CB2

Nitric acid treated, low SA

2.57

22.1

101.1

95.5

58.7

6.4

CB3

Not treated base black

3.66

9.3

38.7

512.5

16.2

9.6

CB4

Nitric acid treated, high SA

2.00

9.42

62.6

528.3

49.7

6.9

CB5

Not treated base black

7.43

25.1

61.99

61.0

5.9

7.0

Notes:

a)       Aggregate size is listed as Dcircle arithmetic number. Samples were dispersed in chloroform, sonicated for 10 minutes, and then measured on TEM

b)      OAN – Oil absorption number; measures porosity/structure. OAN cannot be measured for sulfanilic acid treated grades.

d)      The measurements were made using dynamic light scattering on a Brookhaven Instrument BIC-90. 

Applicant's summary and conclusion

Conclusions:
The surface of particles of not treated nanoforms of carbon black is hydrophobic. This will promote aggregation and agglomeration of the particles in water and hence cause unstable dispersions
Executive summary:

Surface energie measurement of not treated nanoforms and their treated carbon grades was measured. The values ranged from 5.9 to 16.2 mJ/m2 for the not treated nanoforms and 49.7 to 58.7 mJ/m2 for their treated counterparts. The not treated nanoforms were more hydrophobic and had lower surface energies than their acid treated counterparts, respectively. However, the surface treated forms were however still hydrophobic as their surface energies are below 113 mJ/m2, considered the threshold for the commencemnet of hydrophilic behaviour.