Detoxification of mustard gas, nerve agents and simulants by peroxomolybdate in aqueous H2O2 solution: Reactive oxygen species and mechanisms

Abstract

To overcome the insufficient understanding of the detoxification mechanisms of Chemical Warfare Agents (CWAs) and simulants by a molybdate-activated hydrogen peroxide solution (MoO42−-H2O2), detoxification performances toward CWAs and simulants were tested. The detoxification efficacy toward mustard gas (HD), nerve agent GD and VX by using MoO42−-H2O2 was higher than that by using H2O2 activated/modified by sodium hydroxide, ammonia, bicarbonate, and borates, but the vesicant mustard sulfone (HDO2) was only formed when using MoO42−-H2O2 to detoxify HD. Although Reactive Oxygen Species (ROS) such as singlet oxygen (1O2), superoxide anion (O2−), H2O2 and peroxide anion (OOH−) were detected by electron spin resonance (ESR) and chemiluminescence (CL) in the 0.1 M MoO42−-1.0 M H2O2 solution, 95Mo NMR indicated that Mo(O2)42− was the dominant oxidant for the oxidation of sulfide to sulfoxide and then to sulfone. Oxidation of HD by Mo(O2)42− occurred on the HD-drop/water interface through a direct oxygen transfer mechanism without the participation of H2O molecules, and further oxidation of HD to HDO2 was inevitable in an aqueous MoO42−-H2O2 solution. 18O tracer experiments confirmed that OOH−-based perhydrolysis dominated the detoxification reaction of nerve agents in an alkaline H2O2 solution. Considering the balance of oxidation/nucleophilic reactivity for a practical decontaminant, pH 10.5–11 range was recommended as the ideal for the MoO42−-H2O2 system to detoxify CWAs.