Laboratory investigation of the photooxidation of formaldehyde combining FTIR analysis of stable species and HO2 detection by the chemical amplifier technique

The photodissociation of formaldehyde in air at one atmosphere pressure and room temperature has been investigated in a 977 L photoreactor by in situ analysis of stable species by FTIR absorption spectroscopy and of peroxy radicals, HO2, by the chemical amplifier technique, after sampling. The photodissociation coefficient of the channel H2CO+hν (+O2) → 2 HO2+CO (1) determined experimentally was found consistent with that calculated from the absorption spectrum of H2CO and the spectral distribution of the photolysis light. The rate constant k−3 of the thermal decomposition of the adduct formed in the reaction HO2+H2CO↔HOCH2O2 (3, −3) was determined and found at the lower limit of the range of the literature values. This study confirms the potentiality of the chemical amplifier technique in combination with other analytical techniques to investigate chemical mechanisms of atmospheric interest in photoreactors.