Photolytic degradation of molecular iodine adsorbed on model SiO2 particles

A molecular derivatization method followed by gas chromatographic separation coupled with mass spectrometric detection was used to study photolytic degradation of I-2 adsorbed on solid SiO2 particles. This heterogeneous photodegradation of I-2 is studied at ambient temperature in synthetic air to better understand I-2 atmospheric dispersion and environmental fate. The obtained laboratory results show a considerably enhanced atmospheric lifetime of molecular iodine adsorbed on solid media. The heterogeneous atmospheric residence time (tau) of I-2 is calculated to be tau approximate to 187 min, i.e., tau approximate to 3 h. The obtained heterogeneous lifetime of I-2 is shown to be considerably longer than its destruction by its principal atmospheric sink, namely, photolysis. The observed enhanced atmospheric lifetime of I-2 on heterogeneous media will likely have direct consequences on the atmospheric transport of I-2 that influences the toxicity or the oxidative capacity of the atmosphere. (C) 2020 Elsevier B.V. All rights reserved.