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Adsorption / desorption

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Description of key information

From EPI suite KOCWIN Program (v2.00) predicted model the soil adsorption coefficient (Koc) value of 4-aminoazobenzene-3, 4’-disulphonic acid is estimated to be 871.3 L/kg i.e log Koc=2.9401 at 25 deg C,this log Koc value indicating that it is has a Moderate sorption to soil and sediment and therefore have slow migration potential to groundwater.

Key value for chemical safety assessment

Koc at 20 °C:

Additional information

By applying Weight of evidence approach for the target substance 4-aminoazobenzene-3, 4’-disulphonic acid (Cas no.101-50-8) studies are summarized as fallowed:

Both predicted sources i.e EPI Suite and PBT profiler indicate that the test substance4-aminoazobenzene-3, 4’-disulphonic acidhas a moderate sorption to soil and sediment and slow migration potential to groundwater. 

With following Koc values:

EPI SUITE - 871.3 (Log Koc=2.9401)

PBT profiler -870 (Log KoC=2.939)

Other weight of evidence studies for read across chemical from Scientific Bulletin journal (UPB Scientific Bulletin, Series B; Vol. 78, Iss. 1, 2016 P.137-148) indicate that the Soil adsorption test was conducted for test chemical tartrazine by using sorption floatation method.

Initial concentration of test chemical was 5-500 mg/L with pH range of 7-9 at temperature 20 deg C were selected to study tartrazine removal efficiency.

The removal efficiency of chemical tartrazine was found to be 9% using soil as adsorbent in sorption floatation technique.


 Overall all studies concluded that the test substance4-aminoazobenzene-3, 4’-disulphonic acid (Cas no.101-50-8)has a moderate sorption to soil.

[LogKoc: 2.9401]