Novel Photocatalysts and Processes for the Destruction of Chemical Warfare Agents (cwa)

The present research project aims at developing novel photocatalysts for the destruction of chemical warfare agents to innocuous products in gas and liquid phases. The project focuses on understanding the chemistry involved during photodegradation of selected simulants, which can effectively represent chemical warfare agents such as HD, G-type (GA, GB, GD) and VX. Studies addressing the destruction of toxic organics found in other military activities (solvents, purification centers, etc.) will be performed as well. The project combines the synthesis and characterization of novel catalysts, catalytic evaluations with probe molecules and kinetic studies to understand the lability of certain bonds (C-S, C-P, P=O, etc..). Moreover, the project focuses on the development of effective slurry and gas phase reactors including "closed cycle" systems, photocatalysts, which operate with visible/solar radiation and finally use of novel processes such as ultrasound to enhance the photochemical transformation and avoid formation of any toxic intermediates. This paper describes the initial work and research tasks undertaken for testing selected categories of photocatalysts for destruction of organics and CWA simulants, utilization of ultrasound for enhancement of reactant transformation and elimination of byproducts, and development of photocatalysts for operation with visible light. More specifically, we present the initial work we performed on the photodegradation of diethylsulfide (DES) in gas phase (C2H5-S-C2H5) as a simulant of mustard gas (HD) over various titanias utilizing UV light. The main routes of DES degradation are C-S cleavage, S oxidation, α-C and β-C oxidation were revealed. The liquid phase photodegradation of organics in the presence of ultrasound aiming at the enhancement of catalyst reactivity and elimination of any byproducts was studied as well. Effective photocatalysts for operation with visible light were synthesized based on transition metal substituted and loaded MCM41. Extensive work is being performed involving the use of the above approaches for CWA simulants such as diethylsulfide, 2-chloro ethyl-ethyl-sulfide (Cl(CH2)2SCH2CH3) and dimethyl-methylphosphonate (DMMP). INTRODUCTION Over the last decade, numerous studies have been performed aiming at the development of novel technologies for the successful and economic destruction of CWAs to benign products. In view of the seriousness of the problem, the National Research Council (NRC) recommended a new research program [1] to address the chemical neutralization and biodegradation of CWAs. Since then, several attempts combining different methods have been performed. The existing state-of-the-art on this subject has been reviewed in detail by Yang and coworkers [2, 3]. The present research project is a multiyear effort and aims at developing novel photocatalysts, reactors and processes for the destruction of chemical warfare agents to innocuous products in gas and liquid phases. The project focuses on understanding the chemistry involved during photodegradation of selected probe molecules which can effectively represent chemical warfare agents such as HD, Gtype (GA, GB, GD) and VX. The project combines the synthesis and characterization of novel catalysts, catalytic evaluations with probe molecules and kinetic studies to understand the lability of certain bonds (C-S, C-P, P=O, etc..). Moreover, the project focuses on the development of highly Report Documentation Page Form Approved