Ethylenediamine

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)

GLP compliance:

yes (incl. QA statement)

Type of method:

batch equilibrium method

Media:

soil

Radiolabelling:

yes

Test temperature:

25°C

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0.5 to 30 ppm
- Sampling interval: 0,01, 2, 17, and 36 h

Details on matrix:

Six different soils were used. Five were collected from the vadose: two sandy loams, a sandy clay loam, a silty loam, and a clay. The sixth soil was a sand collected from an aquifer.

Details on test conditions:

TEST CONDITIONS
- Buffer: 0,01 M CaNO3
- pH: 7
- Suspended solids concentration: 0,1- 1 g/ 10- 25 ml


TEST SYSTEM
- Type, size and further details on reaction vessel: 50 ml Teflon lined centrifuge tubes
- Amount of soil/sediment/sludge and water per treatment (if simulation test):
- Soil/sediment/sludge-water ratio (if simulation test):
- Number of reaction vessels/concentration: 3
- Are the residues from the adsorption phase used for desorption: Yes

Computational methods:

The adsorption isotherms were best described by the Freundlich equation:
Cs = Kd * Ce1/n.

The adsorption constants were derived by linear regression of the logarithmic form of the equation.
Distribution ratio Dc was determined as concentration of chemical in solution ((µg/g dry weight) divided by chemical in solution (µg/ml).

Type:

Koc

Value:

4 766

Temp.:

25 °C

Type:

log Koc

Value:

3.68

Temp.:

25 °C

Remarks on result:

other: mean value

Relative affinity of EDA to soils was as follows silty loam>sandy clay loam>clay > sandy loam (Londo) > sandy loam (Cecil) > aquifer sand.

Kd varied from 238 for the silty loam to 15 for aquifer sand. Normalizing Kd values to organic content of the soil gave a mean Koc value of 4766 ±1968, log Koc=3.68.

Cation exchange capacity correlated more closely to adsorption than organic content.

	Kd	r^2	Koc	log Koc	Cation Exchange capacity (meq/100g)	foc	Dc [(µmol/g)/ (µmM)]
Sand	15	0.99	6160	3.8	6.9	0.0024	0.067
Sandy Loam (Londo)	69	0.99	2724	3.4	9.2	0.00255	0.1340
Sandy Clay (Loam)	220	0.95	5619	3.7	16.4	0.0391	0.316
Clay	70	0.96	4972	3.7	11.9	0.0140	0.127
Silty Loam	238	0.99	7051	3.8	15.6	0.0337	0.533
Sandy Loam (Cecil)	29	0.99	2071	3.3	3.0	0.0139	0.219

In the desorption test from sandy loam soil, 9% EDA partitioned to the aqueous phase on addition of fresh electrolyte. This remained constant for 4 days. After washing with 0.1M EDA for 24 h 70 -75 % of the ¹⁴C-labelled material was recovered.

Conclusions:

Batch equilibrium adsorption studies were conducted which showed a log Koc of 3.68, indicating relative immobility in soil.

Executive summary:

A study was conducted to determine the adsorption/desorption coefficient (log Koc) of the test substance at neutral pH using batch equilibrium adsorption studies according to OECD Guideline 106, in compliance with GLP. Six different soils were used. Five were collected from the vadose: two sandy loams, a sandy clay loam, a silty loam, and a clay. The sixth soil was a sand collected from an aquifer. The equilibrium adsorption coefficients were calculated in 5 different soils which indicates a relative affinity of the test substance to soils as follows silty loam> sandy clay loam > clay > sandy loam (Londo) > sandy loam (Cecil) > aquifer sand. Under the study conditions, the mean of log Koc in soil was determined to be 3.68 (Davis, 1991).

Description of key information

Koc was determined to be 4766.

Key value for chemical safety assessment

Koc at 20 °C:

4 766

Additional information

A study was conducted to determine the adsorption/desorption coefficient (log Koc) of the test substance at neutral pH using batch equilibrium adsorption studies according to OECD Guideline 106, in compliance with GLP. Six different soils were used. Five were collected from the vadose: two sandy loams, a sandy clay loam, a silty loam, and a clay. The sixth soil was a sand collected from an aquifer. The equilibrium adsorption coefficients were calculated in 5 different soils which indicates a relative affinity of the test substance to soils as follows silty loam > sandy clay loam > clay > sandy loam (Londo) > sandy loam (Cecil) > aquifer sand. Under the study conditions, the mean of log Koc in soil was determined to be 3.68 (Davis, 1991).