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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption / Desorption: The substance is surface active (CMC of 10 mg/L at 21.5 ±0.5 °C) and the Koc value cannot be determined.
For the CSA, the Koc value has been calculated by QSAR (KOCWIN v2.00; Chemservice S.A., 2015c) resulting in a LogKoc of 5.63 (first representative) and 7.174 (second representative). The second value is used for the CSA.

Key value for chemical safety assessment

Koc at 20 °C:
14 927 944

Additional information

The adsorption coefficient was not determined according to EU Method C.19 and OECD Guideline 121 as they were considered not applicable because the test item was highly surface active.

In order to calculate PNECs for the compartments freshwater sediment, marine sediment and soil using the EPM method, a Koc value had to be derived (Chemservice, 2015a). The soil adsorption can be calculated by using KOCWIN. This tool estimates the organic carbon-normalized sorption coefficient for soil (and also for sediment), which is designated as Koc. Two different models are used for this estimation: the Sabljic molecular connectivity (MCI) method as well as with the traditional method which is based on logKow.

For the first representative of the substance Benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs., para-, sodium salts the MCI method reveals a value of 1.416E+6 L/kg as result. For the second representative of the substance Benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs., para-, sodium salts the MCI method reveals a value of 1.493E+7 L/kg as result.

Referring to the Chemical Safety Assessment, a Koc value of 1.493E+7 (LogKoc = 7.174) is taken into consideration.

[LogKoc: 7.174]