UNDERSTANDING THE SURFACE CHEMISTRY OF GAS PHASE ORGANOPHOSPHORUS CHEMICAL WARFARE AGENTS WITH SORBENT MATERIALS

Abstract

Chemical warfare agents (CWAs) pose a serious threat to civilians and warfighters due to their high toxicity and usage in recent attacks. Although existing filtration media (ASZM-TEDA) used in gas mask devices absorbs and decomposes a wide spectrum of CWAs, the filtration performance of this material can be compromised in the battlefield due to poorly understood mechanisms. The high toxicity of CWAs remains a barrier for most research institutions to study these compounds experimentally which hinders the search for improved filtration materials. To overcome this issue, studies are performed using relatively benign simulant compounds that have similar adsorption and decomposition properties as toxic CWAs. In this work, a report of experimental findings will be presented regarding how dimethyl methylphosphonate (DMMP), an organophosphorus CWA simulant, will adsorb and decompose on components that makeup ASZM-TEDA. The work presented in this dissertation deconstructs the components that makeup ASZM-TEDA in order to identify the role of specific metal oxides and the carbon support. This approach was facilitated using different analytical techniques including TGA, FTIR spectroscopy, and DFT modeling to gain a molecular understanding of how DMMP interacts with porous carbon (Chapter 3) and metal oxide nanoparticles/surfaces (Chapters 4 and 5). Lastly, a new method is described (Chapter 6) that overcomes many of the difficulties encountered in conventional measurements that monitor gas phase DMMP adsorption/desorption processes on sorbent materials. This method can be used to obtain reliable quantitative measurements and parameters (e.g. adsorption capacities, ∆Hads, and kads) of low vapor pressure adsorbate/sorbent systems making it particularly useful for CWAs/CWA simulants and new filtration materials (e.g. DMMP and porous carbon).