Adsorption and Destruction of the G-Series Nerve Agent Simulant Dimethyl Methylphosphonate on Zinc Oxide

Abstract

Organophosphorus chemical warfare agents (CWAs) are extremely toxic compounds that are nominally mitigated with gas mask filtration employing metal oxide impregnated activated carbon filtration material. To develop more effective sorbents, it is important to understand the surface chemistry between these organophosphorus compounds and the individual components that make up these filtration materials. In this study, density functional theory (DFT) and Fourier transform infrared spectroscopy (FTIR) were employed to investigate the adsorption and decomposition mechanisms between a sarin simulant molecule, dimethyl methylphosphonate (DMMP), and zinc oxide, which is a component found in current filtration materials. Theoretical calculations show that DMMP readily adsorbs to a pristine and hydroxylated ZnO (101̅0) surface with average adsorption energies of 132 and 65 kJ mol–1, respectively. Experimental diffuse reflectance fourier transform infrared spectroscopy (DRIFTS) reveals that ZnO adsorbs water and readily hydroxylates under ambient conditions, which can facilitate adsorption through hydrogen bonding of the PO to ZnO surface hydroxyls. FTIR gas phase analysis also reveals that DMMP decomposes in the presence of ZnO nanoparticles (NPs) to produce methanol at room temperature. Assuming a fully hydroxylated surface of ZnO, DFT calculations reveal several plausible mechanisms for DMMP decomposition to form methanol with an activation energy barrier of 99.6 kJ mol–1. On the basis of this energy barrier to decompose DMMP, a turnover frequency (TOF) of only 3.5 × 10–7 s–1 is calculated assuming full coverage of DMMP on the ZnO nanoparticles tested. This value is qualitatively consistent with experimental results.

Facile Decomposition of Organophosphonates by Dual Lewis Sites on a Fe3O4(111) Film

“…6 Metal oxides have potential for room temperature decomposition of toxic organophosphonates. Indeed, the surface chemistry of oxides of Fe [7][8][9][10][11][12][13] , Cu [14][15] , Y 16 , Mo 17 , Ti [18][19][20] , Zn 21 and others [22][23][24] has been investigated. A common DMMP reaction pathway for the studied oxides is the dissociation of one of the P-O-CH 3 bonds and the formation of a surface methoxy 15-16, 18, 20 or molecular methanol in the presence of surface hydroxyls.…”

SAW Chemical Array Device Coated with Polymeric Sensing Materials for the Detection of Nerve Agents

“…The center frequency was calculated as 250 MHz because the SAW velocity on the ST-cut quartz substrate was 3158 m/s and the wavelength of the Al electrode was 12.632 µm. and IR spectroscopy [12,13], but most detectors using these methods are heavy, bulky, and consume lots of power. Surface acoustic wave (SAW) sensors, a kind of the chemical detector, are sensitive, small, and require extremely low power to operate [14][15][16][17][18].…”

“…Therefore, early detection is key. Generally, nerve agents can be detected using various techniques such as photoionization [4], ion mobility spectroscopy [5,6], an electric nose [7,8], flame photometry [9][10][11], and IR spectroscopy [12,13], but most detectors using these methods are heavy, bulky, and consume lots of power. Surface acoustic wave (SAW) sensors, a kind of the chemical detector, are sensitive, small, and require extremely low power to operate [14][15][16][17][18].…”

“…Therefore, early detection is key. Generally, nerve agents can be detected using various techniques such as photoionization [ 4 ], ion mobility spectroscopy [ 5 , 6 ], an electric nose [ 7 , 8 ], flame photometry [ 9 , 10 , 11 ], and IR spectroscopy [ 12 , 13 ], but most detectors using these methods are heavy, bulky, and consume lots of power.…”

Chitosan-Derived Porous Activated Carbon for the Removal of the Chemical Warfare Agent Simulant Dimethyl Methylphosphonate

“…Furthermore, owing to possible terror threats, protecting civilians from CWAs has become increasingly important for many governments. The prompt adsorptive removal of toxic agents from various environments is one of the most critical technologies for achieving the rapid detoxification of CWAs [4][5][6].…”