Adsorptive degradation of dimethyl methylphosphonate over Zr-based metal–organic framework built from 3,3′,5,5′-azobenzenetetracarboxylic acid

Abstract

Chemical warfare agents (CWAs) pose a significant threat to humans because of their high toxicity. Zirconium-based metal–organic frameworks (Zr-MOFs) are promising candidates for the purification and detoxification of CWAs. In this study, we prepared a Zr₆O₄(OH)₈(H₂O)₄(abtc)₂ denoted to Zr-abtc (abtc = 3,3′,5,5′-azobenzene-tetracarboxylate) under eco-friendly hydrothermal reflux conditions and investigated its detoxification performance. Dimethyl methylphosphonate (DMMP) was used as a simulant of a nerve agent to evaluate the adsorption performance of Zr–abtc. The Zr–abtc MOF was constructed from an 8-connected Zr₆ cluster [Zr₆(µ₃-O)₄(µ₃-OH)₄] with abtc as a linker, resulting in the generation of abundant surface hydroxyl groups, high porosity, and remarkable structural robustness under high moisture and high temperature conditions. The results of the breakthrough (BT) test of DMMP under dry and humid conditions reveal that Zr–abtc displays high DMMP adsorption performance with the adsorption capacity of 1.74 and 1.60 mmol/g under dry and humid condition, respectively. The high performance of Zr–abtc can be attributed to not only the strong interaction between the surface hydroxyl group of Zr–abtc MOF and DMMP but also the catalytic activity of the surface hydroxyl group to form the decomposed product of DMMP, as demonstrated using Fourier transform infrared spectroscopy (FTIR).