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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Based on available information worst case Koc was selected.

Key value for chemical safety assessment

Koc at 20 °C:
77.62

Additional information

Sorption behaviour of 1H-Benzotriazole and Tolyltriazole have been investigated in several studies during the last decades showing a high mobility in soil. Motivated by findings at an abandoned airport in Norway Breedveld et al. performed a sorption study in six different soils according to OECD 106 (Breedveld et al., 2003). The study has given indications showing very little sorption in different soil matrices increasing with gradient organic carbon content. The maximum adsorption was found in peat at pH 3.0 and an organic carbon content of 47.4 % (estimated log Koc 1.4). Experimental observations were supported by field studies detecting Benzotriazole in various soil samples from the surroundings of the airport at 1.2 m depth.

 Hart et al. have examined the sorption behaviour of 1H-Benzotriazole and 5-Methyl-benzotrizole in short-term batch method according to an ASTM standard method in four different soil matrices with low organic carbon content (Hart et al., 2004). Results from the experiment were fitted by Langmuir, Freundlich and linear isotherms giving indications on different factors affecting the sorption behaviour of both substances. As all members of Benzotriazoles have shown a strong dipole moment (polar character) binding to soil is a complex combination of molecular driving forces with different binding sites for adsorption, absorption and hydrogen bonding. From the experimental results, a maximum log Koc of 1.89 for 1H-Benzotriazole, and 2.04 for 5-Methylbenzotriazole was calculated.

In addition, Jia et al. also have observed non-linear sorption of 1H-Benzotriazole and Tolyltriazole in mineral soils (Jia et al., 2007). A significant increase of sorption of Benzotriazoles was detected when in situ pH of soil equals range of pKa value indicating ionic interactions between triazole molecules and binding sites in soil matter. In general, the observed sorption coefficient of Tolyltriazole has been higher than of Benzotriazole. Furthermore increased sorption has been found when zerovalent Fe(0) has been present indicating multi-layer coverage.

Experimental findings for Benzotriazole and Tolyltriazole was supported by QSAR calculations using KOCWIN v.2.00 (log Koc 1.72 (BT) and 1.94(TT)). In a second estimation according to Schüürmann (Schüürmann et al., 2006) a log Koc of 1.69 for BT has been achieved.

All available information have been adequate to assess the behaviour of Triazoles in soil. Therefore, no need for further testing was assumed. In summary, all results show a log Koc < 3 indicating a high mobility in soil.  

Breedveld GD, Roseth R et al. (2006) Persistence of the de-icing additive benzotriazole at an abandoned airport, Water Air Soil Pollut: Focus 3: 91 -101.

Hart DS, Davis LC et al. (2004) Sorption and partitioning parameters of benzotriazole compounds, Microchem J, 77, 9 -17.

Jia Y, Breedveld GD et al. (2007) Column studies on transport of deicing additive benzotriazole in a sandy aquifer and a zerovalent iron barrier, Chemosphere, 69, 1409 -1418.

Jia Y, Breedveld GD et al. (2007) Sorption of triazoles to soil and iron minerals, Chemosphere, 67, 250 -258.

Schüürmann G, Ebert R, Kühne R (2006) Prediction of the Sorption of Organic Compounds into Soil Organic Matter from Molecular Structure, Environ. Sci. Technol., 40, 7005 -7011.

[LogKoc: 1.89]