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Environmental fate & pathways

Adsorption / desorption

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Description of key information

The adsorption coefficient (Kd) of the substance was determined in a test according to OECD TG 106.  The Kd values are in the range  of 377 - 5863 L/kg for three different soils.  The mean value 2748 L/kg will be used for risk assessment purposes. Because the sorption to soil or sediment is more related to the cation exchange capacity than to the organic matter content of the soil or sediment there is no use to make the Kd soil independent by calculating a Koc. These Kd values can directly be used in risk assessment only for the removal via sorption in a STP where sorption to sludge is different than to soil and sediment, a surrogate Koc of 54953 L/Kg is considered to be representative.

Key value for chemical safety assessment

Koc at 20 °C:
54 953

Other adsorption coefficients

Type:
log Kp (solids-water in soil)
Value in L/kg:
3.439
at the temperature of:
21 °C

Other adsorption coefficients

Type:
log Kp (solids-water in sediment)
Value in L/kg:
3.439
at the temperature of:
21 °C

Other adsorption coefficients

Type:
log Kp (solids-water in suspended matter)
Value in L/kg:
3.74
at the temperature of:
21 °C

Additional information

The distribution of quaternary ammonium compounds, C12 -18 -alkylbis(hydroxyethyl) methyl, chlorides between soil and water was experimentally determined for three soils according to the batch equilibrium method (OECD TG 106, GLP, reliability 1). This method is considered particularly suitable for surfactants. A selection of three standard soils was used representing a range of OC% and pH. It turned out that the OC% of the soils was not the determining characteristic for the extent of sorption.

The Kd was reported to be 377, 2003 and 5863 L/kg for Speyer 2.2 (loamy sand), Eurosoil 4 ((silt) and Speyer 6S (clay) respectively. The mean value 2748 L/kg will be used for risk assessment purposes. Because the sorption to soil or sediment is more related to the cation exchange capacity than to the organic matter content of the soil or sediment there is no use to make the Kd soil independent by calculating a Koc. These Kd values can directly be used in risk assessment only for the removal via sorption in a STP where sorption to sludge is different than to soil and sediment, a surrogate Koc of 54953 L/Kg is considered to be representative.

In the table below , the distribution constants used in this assessment are summarized:

                       Table:Distribution constants for Quaternary ammonium compounds, C12-18-alkylbis(hydroxyethyl)methyl, chlorides

Kpsoil

2748 L.kg-1

Ksoil-water

4122 m3.m-3

Kpsusp

5496 L.kg-1

Ksusp-water

1374 m3.m-3

Kpsed

2748 L.kg-1

Ksed-water

1374 m3.m-3

 

[LogKoc: 4.7]