Photoassisted reaction of sulfur mustard under UV light irradiation.

The photoassisted reaction of sulfur mustard (HD) in both the vapor and droplet states under UV light irradiation was investigated. It was found that HD molecules in either the gas or the condensed phase could be easily converted into other chemicals under the irradiation of a germicidal lamp. The products detected upon reaction suggested that the photoassisted reaction of HD molecules in the gas phase produced a kind of nontoxic heavy polymer, and this method seemed to be applicable for decontamination of air. Nevertheless, the photoassisted reaction of HD droplets would produce a series of products containing -SCH2CH2Cl or -OCH2CH2CI groups, some of which were proven to be even more toxic than HD. Therefore, it was not an effective method forthe decontamination of HD droplets. The obtained experimental results would indicate that two possible pathways might be involved in the destruction of HD molecules: (1) HD molecules may undergo a photochemical reaction upon absorbing photons of sufficient energy, which leads to cleavage the C-S bond in HD molecules at the primary step, or (2) HD molecules could be oxidized by the photogenerated ozone.