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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Due to the cationic surface-active properties will N-[2-(piperazin-1-yl) ethyl]C18-insaturated-alkylamide adsorb strongly onto the solid phase of soil and sediments. The substance can adsorb both onto the organic fraction and, dependent on the chemical composition, onto the surface of the mineral phase, where sodium and potassium ions can be exchanged against the alkyl ammonium ion. The determination of a Koc from log Kow is not opportune, because the common equations for Koc derivation are not valid for both ionic and surface active substances. Therefore not the Koc values should be evaluated but the Kd values. Therefore the Kd values are reported and not the Koc values.

Kd values range from 1000 to 4600 L/kg. For all cationic surfactants the sorption results (Kd) of Eurosoil 4 were used (or other silt soil) as a realistic worst-case representative.

N-(2 -aminoethyl)piperazine which is formed as metabolite in the biodegradation tests has a high Koc of 37000 L/kg indicating that it will be immobile in soil. This high sorption of N-(2 -aminoethyl) piperazine explains the high removal of DOC observed in the sewage treatment simulation study despite the fact that this substance is not degraded.

Key value for chemical safety assessment

Koc at 20 °C:
100 000

Other adsorption coefficients

Type:
log Kp (solids-water in soil)
Value in L/kg:
3.301
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in suspended matter)
Value in L/kg:
3.602
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in sediment)
Value in L/kg:
3.301
at the temperature of:
20 °C

Additional information

The adsorption/desorption behaviour of N-[2-(piperazin-1-yl) ethyl]C18-insaturated-alkylamide on soils was evaluated in a study performed in accordance with OECD testing guideline 106 and GLP requirements. This test was performed for the C18 carbon chain components with 1, 2 and 3 double bonds that represent the main components of the test substance. At the test conditions the adsorption coefficient Kd was found to be in the range of 2300 to 4600 (cm3/g) for the C18:1 component, 1600 to 3300 for the C18:2 component and 1000 to 1900 for the C18:3 component in the different soils tested. Consequently, the test substance is considered to be strongly sorptive to soil/sediment particles.

[LogKoc: 5.0]