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Environmental fate & pathways

Adsorption / desorption

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Description of key information

The adsorption coefficients were calculated using the software PCKOCWIN v1.66 on the basis of the structural formula of the test item components and possible hydrolysis products. As the substance is a UVCB substance hydrolysing at contact with water, several Koc values were estimated (Currenta, 2010c):
- Koc of the constituents ranged form 9114 (2,4-TDI) and 9303 (2,6-TDI) to 2.8E+7 (low molecular TDI-Biuret)
- Koc of 2,4-TDA is 119.9
- Koc of 2,6-TDA is 122.4
- Koc of possible hydrolysis products are 8917 to 6.195E+5
According to Swann et al. (1983), the components and possible hydrolysis products of the substance have a low to high potential to sorb on soil or sediment.

Key value for chemical safety assessment

Additional information

The substance is insoluble or only poor soluble in water. Even using a co-solvent, the test item immediately precipitates after contact with water. Additionally, it hydrolyses in a very short time (within hours) as could be shown in a hydrolysis test. Therefore, an experimentally determination of the adsorption coefficient according to OECD TG 121 is not possible.