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Adsorption/desorption

The adsorption potential was estimated for the substance using the MCI and the Kow methods of the KOCWIN v2.00 module from SRC EPI Suite v4.10. These estimates are representative for uncharged molecules. The substance ionises in aqueous solutions, therefore the adsorption coefficient was calculated according to Franco & Trapp (2008, 2009, 2010) to correct for the charged molecule at pH 5, 7 and 8. The Koc values are listed below.

 

Uncharged molecule:

- MCI method: Koc = 494.6 L/kg; log Koc = 2.69

- Kow method: Koc = 4.52 L/kg; log Koc = 0.66

 

Charged molecule:

- Franco & Trapp, 2008:

pH 5: Koc = 117 L/kg; log Koc = 2.07

pH 7: Koc = 117 L/kg; log Koc = 2.07

pH 8: Koc = 116 L/kg; log Koc = 2.06

 

Based on the corrections for the charged molecule according to Franco & Trapp (2008, 2009, 2010), significant adsorption to the solid soil phase is not expected.

Henry´s Law constant

The measured pKa of 9.6 (SPARC modelling) indicates that the substance will primarily exist as a cation in the environment. Therefore the method described in the REACH Guidance Document R7a, Appendix R.7.1 -2 (pH correction of partition coefficients for ionisable substances, p. 189) was applied to correct for the pH. The HLC was corrected for the charged molecule to a value of 1.75E-11 Pa*m³/mol at pH 7 (range: 1.76E-13 to 1.38E-09 Pa*m³/mol, pH 5 to 9; BASF SE, 2013).

In conclusion, the HLC of the charged molecule is expected to be < 1 Pa*m³/mol (pH 7, 25°C). Therefore, from the water surface the substance will not evaporate into the atmosphere.

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