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Environmental fate & pathways

Adsorption / desorption

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Description of key information

A test on adsorption/desorption is not needed as the test substance decomposes rapidly. Adsorption/desorption to soil is not expected due to the low Log Pow (-1.3) and the calculated Koc value of 1.6 .

Key value for chemical safety assessment

Koc at 20 °C:
1.607

Additional information

As a test is not required for substances that decompose rapidly, a measured Kocis not available. For completeness and because data on adsorption potential are needed for the exposure and hazard assessment, the Kocwas calculated using the QSAR tool EPI Suite developed by US-EPA. The Kocfor Sulfonic acids, C14-16 (even numbered)-alkane hydroxy and C14-16 (even numbered)-alkene, sodium salts is 1.607 (if the experimental log Kowof -1.3 is entered into the program). However, one should keep in mind that surfactancy (the fact that surfactants tend to stay in the boundary layer between the phases) and dissociation is not taken into account in the EPI Suite estimations. Therefore calculated Kocvalues should be used with caution. Urano (1984) studied the adsorption of C12-AOS in several sediments collected in Japanese rivers. The experiments were carried out at 25 °C and pH 7.0 ± 0.5. The adsorption isotherms were found to be nearly equal for the various sediments. Adsorption was determined by the content of organic substances. For C12-AOS the Kocwas 0.65. It is expected that the adsorption potential for all alpha olefin sulfonates is low. This is supported by the low measured Log Powof -1.3 of Sulfonic acids, C14-16 (even numbered)-alkane hydroxy and C14-16 (even numbered)-alkene, sodium salts and the low measured Kocfor C12 in sediment.