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Environmental fate & pathways

Phototransformation in air

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The photodegradation of oleic-acid IQAC in air by reaction with OH radicals was calculated using EPIWIN v3.20, AOPWIN v1.92. Based on the reaction rate constant k(OH) =130 x 10E-12 cm³/molecule x sec (cis isomer) and k(OH) =137 x 10E-12 cm³/molecule x sec (trans isomer) and assuming a OH radical concentration of 5 x 10E5 radicals/cm³ half-lives of 2.96 and 2.79 h, respectively can be calculated.

The photodegradation of Oleic-acid based IQAC, DMS quaternised in air by reaction with ozone was also calculated using EPIWIN v3.20, AOPWIN v1.92. Based on the reaction rate constant k(O3) =13.0 x 10E-17 cm³/molecule x sec (cis isomer) and k(O3) =20.0 x 10E-17 cm³/molecule x sec (trans isomer) and assuming a ozone concentration of 7 x 10E11 molecules/cm³ half-lives of 2.116 and 1.375 h, respectively can be calculated.

These half-lives indicate that the substance entering the atmosphere will be very quickly photodegraded by reaction with OH radicals and ozone. Due to the very low vapour pressure and the very low Henry's Law Constant the substance under investigation will not be present in the gas phase in the atmosphere in appreciable amounts and therefore this elimination path will be only of minor importance.