NBC Filter Performance

Morrison, Robert W.

doi:10.21236/ada397007

Cited by 14 publications

(21 citation statements)

References 1 publication

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“…While activated carbon was the first filtration material implemented during the First World War to defend against CWAs, eventually transition metal oxide impregnates were included, these imparting increased reactive sorption capability to decompose adsorbed agents . Today, modern CWA filtration materials are comprised of an ASZM-TEDA formulation, in which copper, molybdenum, zinc, and trace amounts of silver metal oxide particles are impregnated into activated carbon filters along with triethylene diamine . In general, transition metal oxides are a promising class of materials for adsorbing and decomposing CWAs due to their acid/base and redox properties; a robust literature investigating such species has accumulated over the last few decades.…”

Section: Introductionmentioning

confidence: 99%

Adsorption and Decomposition of Dimethyl Methylphosphonate on Size-Selected Zirconium Oxide Trimer Clusters

et al. 2021

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In recent years, zirconium hydroxide powder and zirconium-based metal organic frameworks have found promising applications as chemical warfare agent (CWA) decomposition materials. While bulk zirconium oxide (ZrO2) has proven to be relatively inactive for such purposes, well-controlled fundamental studies investigating the potential CWA decomposition propensity of subnanoscale zirconium oxide, in which undercoordinated metal centers abound, are still severely lacking. Herein, the adsorption and decomposition of the nerve agent simulant dimethyl methylphosphonate (DMMP) on size-selected zirconium oxide trimer, that is, (ZrO2)3, clusters supported on highly oriented pyrolytic graphite (HOPG), have been investigated via the combination of X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption/reaction (TPD/R). XPS measurements acquired for the DMMP-adsorbed, HOPG-supported clusters at a preparation temperature of 298 K, and also after annealing to several successively higher temperatures of 473, 573, and 673 K, elucidated the uptake of DMMP to the (ZrO2)3 clusters, with one DMMP molecule adsorbed per cluster and virtually no thermal molecular desorption observed up to 673 K. These measurements also showed dissociative adsorption of DMMP at room temperature on some clusters, likely via scission of a P–OCH3 bond in DMMP, with further decomposition accompanying an increase in temperature above 473 K. TPD/R experiments showed the evolution of methanol as a major reaction product via two distinct pathways, with desorption peaks centered around 410 and 575 K. Evolution of dimethyl ether and formaldehyde as minor reaction products was also observed with desorption peaks centered around 560 and 620 K, respectively. A second TPD/R cycle following cluster-induced DMMP decomposition resulted in no detected decomposition chemistry, showing DMMP decomposition on the (ZrO2)3 clusters to be stochiometric and non-catalytic, whereby the remaining P-containing species poisoned the clusters.

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Section: Introductionmentioning

confidence: 99%

Adsorption and Decomposition of Dimethyl Methylphosphonate on Size-Selected Zirconium Oxide Trimer Clusters

et al. 2021

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“…The most widely-used material in gas-mask filters for commercial, industrial, and military applications is ASZM-TEDA®, a high surface area composite of porous, activated carbon adsorbent impregnated with triethylenediamine (TEDA) and compounds (presumably oxides) of Cu ('A'), Ag ('S'), Zn ('Z'), and Mo ('M'). 9 While gas-mask filters containing ASZM-TEDA® provide temporary, broad-spectrum protection against many toxic agents, little is known about the fundamental chemistry of organophosphonate adsorption/decomposition on the individual metal oxide components. 9 Non-catalytic decomposition of organophosphonate nerve agents on the metal oxide components may block active sites or could inadvertently yield other toxic, volatile compounds that could penetrate the filter.…”

Section: Introductionmentioning

confidence: 99%

“…9 While gas-mask filters containing ASZM-TEDA® provide temporary, broad-spectrum protection against many toxic agents, little is known about the fundamental chemistry of organophosphonate adsorption/decomposition on the individual metal oxide components. 9 Non-catalytic decomposition of organophosphonate nerve agents on the metal oxide components may block active sites or could inadvertently yield other toxic, volatile compounds that could penetrate the filter. Thus, a detailed understanding of the surface chemistry of metal oxides in the presence of organophosphonates is required for the design of more effective filtration materials and a more robust understanding of failure mechanisms in current materials.…”

Section: Introductionmentioning

confidence: 99%

“…Dimethyl methylphosphonate (DMMP, Figure 1) is a widely studied simulant molecule that has been shown to effectively mimic sarin (GB) adsorption during filter life testing. 9 Removal of the highly labile P-F bond eliminates the AChE inhibiting properties of sarin, while the other functional groups (phosphoryl, methyl, and alkoxy) are retained in DMMP. This makes DMMP an effective simulant for CWA adsorption (through the P=O moiety), but the lack of the P-F bond makes it unclear whether DMMP decomposition on any particular metal oxide surface effectively mimics CWA decomposition on that same surface.…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopic and Computational Investigation of Room-Temperature Decomposition of a Chemical Warfare Agent Simulant on Polycrystalline Cupric Oxide

et al. 2017

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Certain organophosphorous molecules are infamous due to their use as highly toxic nerve agents. The filtration materials currently in common use for protection against chemical warfare agents were designed before organophosphorous compounds were used as chemical weapons. A better understanding of the surface chemistry between simulant molecules and the individual filtration-material components is a critical precursor to the development of more effective materials for filtration, destruction, decontamination, and/or sensing of nerve agents. Here, we report on the surface adsorption and reactions of a sarin simulant molecule, dimethyl methylphosphonate (DMMP), with cupric oxide surfaces. In situ ambient pressure X-ray photoelectron and infrared spectroscopies are coupled with density functional calculations to propose mechanisms for DMMP decomposition on CuO. We find extensive room temperature decomposition of DMMP on CuO, with the majority of decomposition fragments bound to the CuO surface. We observe breaking of PO-CH3, P-OCH3, and P-CH3 bonds at room temperature. On the basis of these results, we identify specific DMMP decomposition mechanisms not seen on other metal oxides. Participation of lattice oxygen in the decomposition mechanism leads to significant changes in chemical and electronic surface environment, which are manifest in the spectroscopic and computational data. This study establishes a computational baseline for the study of highly toxic organophosphorous compounds on metal oxide surfaces.

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“…In a further step towards predictive calculations of CWAs on surfaces, we here report results of joint APXPS and DFT studies of adsorption and decomposition of DMMP on polycrystalline MoO 2 , a model for the MoO x component in ASZM-TEDA© gas filtration materials [12]. Beginning with the adsorption of DMMP on polycrystalline MoO 2 , APXPS measurements at pressures up to 10 mTorr of DMMP were analyzed.…”

Section: Introductionmentioning

confidence: 99%

Dimethyl methylphosphonate adsorption and decomposition on MoO₂ as studied by ambient pressure x-ray photoelectron spectroscopy and DFT calculations

Head¹,

Tsyshevsky²,

Trotochaud³

et al. 2018

J. Phys.: Condens. Matter

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Organophosphonates range in their toxicity and are used as pesticides, herbicides, and chemical warfare agents (CWAs). Few laboratories are equipped to handle the most toxic molecules, thus simulants such as dimethyl methylphosphonate (DMMP), are used as a first step in studying adsorption and reactivity on materials. Benchmarked by combined experimental and theoretical studies of simulants, calculations offer an opportunity to understand how molecular interactions with a surface changes upon using a CWA. However, most calculations of DMMP and CWAs on surfaces are limited to adsorption studies on clusters of atoms, which may differ markedly from the behavior on bulk solid-state materials with extended surfaces. We have benchmarked our solid-state periodic calculations of DMMP adsorption and reactivity on MoO with ambient pressure x-ray photoelectron spectroscopy studies (APXPS). DMMP is found to interact strongly with a MoO film, a model system for the MoO component in the ASZM-TEDA© gas filtration material. Density functional theory modeling of several adsorption and decomposition mechanisms assist the assignment of APXPS peaks. Our results show that some of the adsorbed DMMP decomposes, with all the products remaining on the surface. The rigorous calculations benchmarked with experiments pave a path to reliable and predictive theoretical studies of CWA interactions with surfaces.

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NBC Filter Performance

Cited by 14 publications

References 1 publication

Adsorption and Decomposition of Dimethyl Methylphosphonate on Size-Selected Zirconium Oxide Trimer Clusters

Adsorption and Decomposition of Dimethyl Methylphosphonate on Size-Selected Zirconium Oxide Trimer Clusters

Spectroscopic and Computational Investigation of Room-Temperature Decomposition of a Chemical Warfare Agent Simulant on Polycrystalline Cupric Oxide

Dimethyl methylphosphonate adsorption and decomposition on MoO₂ as studied by ambient pressure x-ray photoelectron spectroscopy and DFT calculations

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NBC Filter Performance

Cited by 14 publications

References 1 publication

Adsorption and Decomposition of Dimethyl Methylphosphonate on Size-Selected Zirconium Oxide Trimer Clusters

Adsorption and Decomposition of Dimethyl Methylphosphonate on Size-Selected Zirconium Oxide Trimer Clusters

Spectroscopic and Computational Investigation of Room-Temperature Decomposition of a Chemical Warfare Agent Simulant on Polycrystalline Cupric Oxide

Dimethyl methylphosphonate adsorption and decomposition on MoO2 as studied by ambient pressure x-ray photoelectron spectroscopy and DFT calculations

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Dimethyl methylphosphonate adsorption and decomposition on MoO₂ as studied by ambient pressure x-ray photoelectron spectroscopy and DFT calculations