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Environmental fate & pathways

Adsorption / desorption

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Description of key information

log Koc 2.5 - 17.3  (KOCWIN v2.00)

Key value for chemical safety assessment

Additional information

No experimental studies investigating the adsorption/desorption potential of the UVCB substance sorbitan C16-18 (even numbered) fatty acid esters, ethoxylated (1-6.5 moles ethoxylated) are available. Therefore, the Koc was calculated using KOCWIN v2.00 based on the Molecular Connectivity Index (MCI) and the log Pow. Based on the composition of the substance, the QSAR calculation was conducted for the 4 main substance components. The results of the QSAR calculations resulted in log Koc values ranging between 2.5 and 17.3 (based on MCI). The log Koc values based on log Kow were calculated to be between 1.8 and 11.2. These values indicate a low to high adsorption potential for main parts of the UVCB substance sorbitan C16-18 (even numbered) fatty acid esters, ethoxylated (1-6.5 moles ethoxylated). Due to high molecular weight and high log Kow, the main constituents are partially not in the applicability domain of the model. However, the molecular structure also indicates a potential of surface active properties, which are not taken into account by the model calculation. The adsorption of non-ionic surfactants to soil is generally high, as shown experimentally for sorbitan polyethoxylate (Chu and So, 2001; Laha et al, 2009 and references therein). Thus, based on the tendency given by the calculated values in combination with the surface active properties, sorbitan C16-18 (even numbered) fatty acid esters, ethoxylated (1-6.5 moles ethoxylated) has a high potential to adsorb to organic particles in sediment and soil.


Chu, W., So, W.S., 2001. Modeling the two stages of surfactant-aided soil-washing. Water Res. 35 (3), 182–188.

Laha, S., Tansel, B., Ussawarujikulchai, A., 2009. Surfactant-soil interactions during surfactant amended remediation of contaminated soils by hydrophobic organic compounds: a review. J. Environ. Manage. 90, 95–100.