Battling Chemical Weapons with Zirconium Hydroxide Nanoparticle Sorbent: Impact of Environmental Contaminants on Sarin Sequestration and Decomposition

The promising reactive sorbent zirconium hydroxide (ZH) was challenged with common environmental contaminants (CO₂, SO₂, and NO₂) to determine the impact on chemical warfare agent decomposition. Several environmental adsorbates rapidly formed on the ZH surface through available hydroxyl species and coordinatively unsaturated zirconium sites. ZH decontamination effectiveness was determined using a suite of instrumentation including in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to monitor sarin (GB) decomposition in real time and at ambient pressure. Surface products were characterized by ex situ X-ray photoelectron spectroscopy (XPS). The adsorption enthalpies, entropies, and bond lengths for environmental contaminants and GB decomposition products were estimated using density functional theory (DFT). Consistent with the XPS and DRIFTS results, DFT simulations predicted the relative stabilities of molecular adsorbates and reaction products in the following order: CO₂ < NO₂ < GB ≈ SO₂. Microbreakthrough capacity measurements on ZH showed a 7-fold increase in the sorption of NO₂ vs SO₂, which indicates differences in the surface reactivity of these species. GB decomposition was rapid on clean and CO₂-dosed ZH and showed reduced decomposition on SO₂- and NO₂-predosed samples. Despite these findings, the total GB sorption capacity of clean and predosed ZH was consistent across all samples. These data provide insight into the real-world use of ZH as a reactive sorbent for chemical decontamination applications.