Decontamination of VX with Acid-Activated Clay

Abstract

The decontamination ability of montmorillonite-based acid-activated clay (AACL) toward the chemical warfare agents (CWAs) mustard gas (HD), soman (GD), and venomous agent X (VX) is evaluated using gas chromatography–flame ionization detection (GC-FID) with internal standard calibration. Unlike HD and GD, VX rapidly reacts with AACL; 99.6% of VX is chemically decontaminated within 10 min. Further investigation into the interaction of AACL with VX revealed that the initial rate of the reaction depends on the concentration of acid on the surface of AACL (the measured pH), suggesting that the formation of a protonated VX intermediate is involved. This reaction occurs in a stoichiometric manner, and surface-bound degradation products are identified and estimated using gas chromatography–mass spectrometry (GC-MS), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FESEM-EDS). The optimized weight ratio of AACL to VX is 40:1 when the reaction time is fixed at 10 min. AACL also shows good adsorption capacity for CWAs, with more than 96% of CWAs physically removed by adsorption. These results not only suggest an essential design strategy for the development of reactive sorbents for VX but also indicate that AACL, which can be mass-produced at low cost, can be regarded as a promising material for immediate decontamination of CWAs.