Solid-Phase Detoxification of Chemical Warfare Agents using Zirconium-Based Metal Organic Frameworks and the Moisture...

Zirconium-based metal organic frameworks (Zr-MOFs) are highly chemically and thermally stable and have been of particular interest as reactive sorbents for chemical warfare agent (CWA) removal due to their fast and selective reactivity toward CWAs reported in buffer solutions. However, we find that decontamination of neat CWAs directly on Zr-MOFs, UiO-66, UiO-66-NH₂, and NU-1000 is rather slow, and the reactivity trend and products generated are very different from those in solution. Furthermore, we show that their decontamination rates are affected by the amount of moisture present in the MOFs. Although the effects are minor for UiO-66-NH₂ and NU-1000, the hydrolytic activity of UiO-66 toward CWAs dramatically improves as the amount of water present increases. Specifically, the initial hydrolysis rate of methyl paraoxon by UiO-66 increases from 6 μmol/d with 0 wt % water loading to 140 μmol/d with 400 wt % water loading. The results reported here suggest that decontamination of CWAs by Zr-MOFs in solid phase behaves very differently than solution decontamination. Additionally, we present for the first time a digestion method for analyzing and quantifying solid-phase decontamination, which is a daunting challenge itself due to the lack of a convenient analytical method.