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Environmental fate & pathways

Phototransformation in air

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Link to relevant study record(s)

Description of key information

The experimentally-derived second-order rate constant for indirect photolysis with OH radical was determined to be 8.06 (± 0.77) E-12 molecules*cm3-18sec-1 at 294 K (21 °C). This equates to an estimated half-life of 16 hrs. at an assumed OH radical conc. of 1.5E6 molecules/cm3.     

Key value for chemical safety assessment

Half-life in air:
16 h

Additional information

The experimentally-derived second-order rate constant for indirect photolysis with OH radical was determined to be 8.06 (± 0.77) E-12 molecules*cm3-18sec-1 at 294 K (21 °C). This equates to an estimated half-life of 16 hrs. at an assumed OH radical conc. of 1.5E6 molecules/cm3. The experimental value cited in the AOPWIN v1.92a software is an arithmetic mean of this Key Study value and various other reported measurements from the literature. The Key Study also showed negligible reaction of biphenyl with ozone and nitrate radical, and the supporting study of Freitag et al. showed negligible reaction under direct photolysis conditions. Thus, the indirect photolysis with OH radical is the dominant process affecting fate of biphenyl in the atmosphere