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Adsorption / desorption

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Endpoint:
adsorption / desorption: screening
Type of information:
(Q)SAR
Adequacy of study:
other information
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
results derived from a (Q)SAR model, with limited documentation / justification
Principles of method if other than guideline:
PCKOCWIN v. 1.66 (2000)
GLP compliance:
no
Type of method:
other: calculated
Media:
soil
Type:
Koc
Value:
309
Type:
log Koc
Value:
2.49

Executive summary:

QSAR calculation (Bayer Industry Services, 2006):


The Koc and logKoc value was calculated with the software EPI Suite (PCKOCWIN v. 1.66, 2000). The QSAR calculation resulted in the following values: Koc = 309 and logKoc = 2.49.

Endpoint:
adsorption / desorption, other
Remarks:
adsorption
Type of information:
experimental study
Adequacy of study:
other information
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Principles of method if other than guideline:
Sorption experiments were performed according to:
Haderlein, S. B.; Schwarzenbach, R. P. Environ. Sci. Technol. 1993, 27, 316-26.
Media:
soil
Specific details on test material used for the study:
- Name of test material (as cited in study report): 3-nitrotoluene, 3 NT
- Analytical purity: > 97 %
Details on study design: HPLC method:
HPLC Analysis. Aqueous NAC concentrations were determined by direct injection of aqueous samples on a reversed phase HPLC system equipped with UV/vis detection at the wavelength of maximum absorption for each NAC (columns: RP-8 or RP-18 stainless steel cartridges, 4 x 125 mm, 5 ím spheres, Merck (Frankfurt, Germany), injection volume 5-100 íL, syringe injection into a Rheodyne valve manually or by auto sampler (Gynkotek Gina 50)). The mobile phase was a mixture of methanol/water for theneutral compounds andmethanol/water containing 10% of 0.01 M phosphate buffer, titrated to pH 2.5 for the analysis of the substituted phenols (ion suppression chromatography). Methanol/water ratios ranged from 1:1 (v/v) to 4:1 (v/v) in order to obtain capacity factors of the analytes between 2 and 5. The flow rate was 0.5-1.5 mL min-1. Calibration by external standards was linear in the range from 5 x 10-12 to 2 x10-9 mol of NAC injected. The
precision of the HPLC method was typically 2-4% RSD.

Adsorption of 3-nitrotoluene (and other nitroaromatic compounds) to 3 homoionic kalium ion clay minerals was determined:
1. Kaolinite
- Distribution coefficient Kd (l/kg dry matter) 2.5
2. Illite
- Distribution coefficient Kd (l/kg dry matter) 13
3. Montmorillonite
- Distribution coefficient Kd (l/kg dry matter) 21
Further results were:
- Adsorption of nitroaromatic compounds is high when the exchangeable cations at the clays include K+ or NH4+ but much smaller for homoionic clays containing Na+, Ca2+, Mg2+, and Al3+
- Highest adsorption coefficients are found for polynitroaromatic compounds
- Ionic strength (in the range of 0.0001 - 0.1 M) had no measurable effect on the adsorption
It is rationalized that electron donor-acceptor complex formation occurs with oxygene at the external siloxane surface of clay minerals (which increases in the aforementioned order of the three minerals). The mobility of nitroaromatic compounds decreases with increasing degree of nitration. Bulky alkyl groups decrease the adsorption although 3-nitrotoluene is more strongly adsorbed than nitrobenzene.

Executive summary:

Haderlein, 1996


Adsorption of 3-nitrotoluene (and other nitroaromatic compounds) to 3 homoionic kalium ion clay minerals was determined:
1. Kaolinite
- Distribution coefficient Kd (l/kg dry matter) 2.5
2. Illite
- Distribution coefficient Kd (l/kg dry matter) 13
3. Montmorillonite
- Distribution coefficient Kd (l/kg dry matter) 21
Further results were:
- Adsorption of nitroaromatic compounds is high when the exchangeable cations at the clays include K+ or NH4+ but
much smaller for homoionic clays containing Na+, Ca2+, Mg2+, and Al3+
- Highest adsorption coefficients are found for polynitroaromatic compounds
- Ionic strength (in the range of 0.0001 - 0.1 M) had no measurable effect on the adsorption
It is rationalized that electron donor-acceptor complex formation occurs with oxygen at the external siloxane surface
of clay minerals (which increases in the aforementioned order of the three minerals). The mobility of nitroaromatic compounds decreases with increasing degree of nitration. Bulky alkyl groups decrease the adsorption although 3-nitrotoluene is more strongly adsorbed than nitrobenzene.

Endpoint:
adsorption / desorption, other
Remarks:
adsorption
Type of information:
experimental study
Adequacy of study:
other information
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment
Remarks:
only basic data given
Principles of method if other than guideline:
Stainless steel columns containing weathered basalt were used for sorption studies to estimate the mobility of munition residues (e.g. p-nitrotoluene) in the aquifer material according to Patterson et al. (1996).
GLP compliance:
not specified
Media:
soil
Specific details on test material used for the study:
- Name of test material (as cited in study report): 3-nitrotoluene, 3 NT
- Analytical purity: not reported

Kd = 2.0 l/kg (relative to bromide)


Kd = 1.2 l/kg (relative to 2-nitrotoluene)

Executive summary:

Toze, 1999


Soil adsorption coefficient (Kd) for 3-nitrotoluene:


Kd = 2.0 l/kg (relative to bromide)


Kd = 1.2 l/kg (relative to 2-nitrotoluene)

Endpoint:
adsorption / desorption: screening
Type of information:
other: BUA report
Adequacy of study:
other information
Reliability:
other: BUA report
Rationale for reliability incl. deficiencies:
other: No reliability is given as this is a summary entry for the BUA report.
Principles of method if other than guideline:
BUA report
GLP compliance:
no

BUA report (1989):


No soil sorption coefficient figures are available.


The investigation on water seeping from a waste dump at Allendorf, Hessen (Germany), where wastes from the production of the explosive trinitrotoluene had been deposited during World War II, and that on untreated well water in the vicinity of this dump, which is treated to obtain drinking water, indicate a high degree of adsorption and/or elimination of nitrotoluenes as they pass horizontally through the soil. The elimination may result from the degradation of the nitrotoluenes, e.g. by soil organisms and/or from the volatility of the mononitrotoluenes (Haas and Loew, 1986).

Executive summary:

BUA report (1989):


No soil sorption coefficient figures are available.


The investigation on water seeping from a waste dump at Allendorf, Hessen (Germany), where wastes from the production of the explosive trinitrotoluene had been deposited during World War II, and that on untreated well water in the vicinity of this dump, which is treated to obtain drinking water, indicate a high degree of adsorption and/or elimination of nitrotoluenes as they pass horizontally through the soil. The elimination may result from the degradation of the nitrotoluenes, e.g. by soil organisms and/or from the volatility of the mononitrotoluenes (Haas and Loew, 1986).

Description of key information

For transported isolated intermediates according to REACh, Article 18, this endpoint is not a data requirement. However, data is available for this endpoint and is thus reported under the guidance of "all available data".


BUA report (1989):


No soil sorption coefficient figures are available.


The investigation on water seeping from a waste dump at Allendorf, Hessen (Germany), where wastes from the production of the explosive trinitrotoluene had been deposited during World War II, and that on untreated well water in the vicinity of this dump, which is treated to obtain drinking water, indicate a high degree of adsorption and/or elimination of nitrotoluenes as they pass horizontally through the soil. The elimination may result from the degradation of the nitrotoluenes, e.g. by soil organisms and/or from the volatility of the mononitrotoluenes (Haas and Loew, 1986).


Toze, 1999:


Soil adsorption coefficient (Kd) for 3-nitrotoluene:


Kd = 2.0 l/kg (relative to bromide)


Kd = 1.2 l/kg (relative to 2-nitrotoluene)


Haderlein, 1996


Adsorption of 3-nitrotoluene (and other nitroaromatic compounds) to 3 homoionic kalium ion clay minerals was determined:
1. Kaolinite
- Distribution coefficient Kd (l/kg dry matter) 2.5
2. Illite
- Distribution coefficient Kd (l/kg dry matter) 13
3. Montmorillonite
- Distribution coefficient Kd (l/kg dry matter) 21
Further results were:
- Adsorption of nitroaromatic compounds is high when the exchangeable cations at the clays include K+ or NH4+ but much smaller for homoionic clays containing Na+, Ca2+, Mg2+, and Al3+
- Highest adsorption coefficients are found for polynitroaromatic compounds
- Ionic strength (in the range of 0.0001 - 0.1 M) had no measurable effect on the adsorption
It is rationalized that electron donor-acceptor complex formation occurs with oxygen at the external siloxane surface
of clay minerals (which increases in the aforementioned order of the three minerals). The mobility of nitroaromatic compounds decreases with increasing degree of nitration. Bulky alkyl groups decrease the adsorption although 3-nitrotoluene is more strongly adsorbed than nitrobenzene.


QSAR calculation (Bayer Industry Services, 2006):


The Koc and logKoc value was calculated with the software EPI Suite (PCKOCWIN v. 1.66, 2000). The QSAR calculation resulted in the following values: Koc = 309 and logKoc = 2.49.

Key value for chemical safety assessment

Additional information