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Environmental fate & pathways

Phototransformation in air

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Description of key information

Degradation rate constant with OH radicals: 1.3 - 1.7 × 10E-15cm3/molecule/sec
GWP: 3500 (100 years time horizon)

Key value for chemical safety assessment

Additional information

The atmospheric degradation for HFC 227ea involves the initial reaction with hydroxyl radicals in the troposphere.

The constant rate for the OH radicals-mediated photodegradation has been experimentally determined by several groups. Tokuhashi al. (2004) reports a rate constant of 1.34 ± 0.08 × 10 -15cm3/molecule/sec at 298 °K. A similar value of 1.7 × 10 -15cm3/molecule/sec is listed in Evaluation Number 14 of JPL NASA (2003), as a result of a combined fit of different experimental data.

The global atmospheric lifetime of HFC 227ea is listed in the IPCC third assessment (2001). An official value of 33 years was estimated considering the tropospheric lifetime, relative to CH3CCl3, at 272 °K, a default stratospheric loss of 8% of the tropospheric loss and an oceanic lifetime of 10650 years.

A global warming potential of 3500 was calculated for a time horizon of 100 years, by considering the calculated global atmospheric lifetime and a radiative efficiency of 0.30 Wm-2ppb-1 (IPCC, 2001)