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Environmental fate & pathways

Adsorption / desorption

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Description of key information

The adsorption behavior of TMAH pentahydrate was studied in three different soils, including a loamy sand (Speyer 2.2 soil; %oc 1.87), a sandy loam (Speyer 2.3 soil; %oc 0.94) and a clay soil (Speyer 6S soil; %oc 1.64).
Adsorption kinetics were determined at an initial TMAH pentahydrate concentration of approximately 10 mg/L. A rapid increase of the adsorption of TMAH pentahydrate to the soils in the first 3 hours contact time was observed for all three soils. The adsorption plateau was reached after 24 hours for all three soils.
Adsorption isotherms were determined over a TMAH pentahydrate concentration range of 0.25 – 25 mg/L and a contact time of 24 hours. TMAH pentahydrate adsorption isotherms could be described by the Freundlich equation. KFoc was determined to be 87.3 (1/n=0.84) , 585 (1/n=0.64) and 1017 (1/n=0.77) mL/g for the soil Speyer 2.2, Speyer 2.3 and Speyer 6S, respectively. The mean Koc for the three soils was 563 mL/g.
The present study is classified as reliable without restrictions according to OECD Guideline 106.

Key value for chemical safety assessment

Koc at 20 °C:
563

Additional information

[LogKoc: 2.8]