Synthesis and characterization of TiO₂/Mg(OH)₂ composites for catalytic degradation of CWA surrogates

Surface catalyzed reactions can be a convenient way to deactivate toxic chemical warfare agents (CWAs) and remove them from the contaminated environment. In this study, pure titanium oxide, magnesium hydroxide, and their composites TiO₂/Mg(OH₂) were prepared by thermal decomposition and precipitation of the titanium peroxo-complex and/or magnesium nitrate in an aqueous solution. The as-prepared composites were examined by XRD, XPS, HRTEM, and nitrogen physisorption. Their decontamination ability was tested on CWA surrogates and determined by high-performance liquid chromatography (HPLC) and gas chromatography coupled with mass spectrometry (GC-MS). Dimethyl methyl phosphonate (DMMP) was used as a G simulant for the nerve agents sarin (GB) and soman (GD) while 2-chloroethyl ethyl sulfide (2-CEES) and 2-chloroethyl phenyl sulfide (2-CEPS) were used as surrogates of sulfur mustard (HD). The activity of the as-prepared composites was correlated with acid-base properties determined by potentiometric titrations and pyridine adsorption studied by in situ DRIFTS. The mixing of Ti and Mg led to an increase of the surface area and the amount of surface -OH groups (with an increasing amount of Ti) that caused improved degradation of DMMP.