Destruction Of Chemical Agents Research Articles

Macromorphological Control of Zr-Based Metal-Organic Frameworks for Hydrolysis of a Nerve Agent Simulant.

Zirconium-based metal-organic frameworks (MOFs) have become one of the most promising materials for the adsorption and destruction of chemical warfare agents. While numerous studies have shown differences in reactivity based on MOF topology and postsynthetic modification, the understanding of how modifying MOF macromorphology is less understood. MOF xerogels demonstrate modified defect levels and larger porosity, which increase the number of and access to potential active sites. Indeed, UiO-66 and NU-901 xerogels display reaction rates 2 and 3 times higher, respectively, for the hydrolysis of DMNP relative to their powder morphologies. Upon recycling, MOF-808 xerogel outperforms MOF-808 powder, previously noted as the fastest Zr6 MOF for hydrolysis of organophosphate nerve agents. The increase in reactivity is largely driven by a higher external surface area and the introduction of mesoporosity to previously microporous materials.

Advances in Metal-Organic Frameworks for the Removal of Chemical Warfare Agents: Insights into Hydrolysis and Oxidation Reaction Mechanisms.

The destruction of chemical warfare agents (CWAs) is a crucial area of research due to the ongoing evolution of toxic chemicals. Metal-organic frameworks (MOFs), a class of porous crystalline solids, have emerged as promising materials for this purpose. Their remarkable porosity and large surface areas enable superior adsorption, reactivity, and catalytic abilities, making them ideal for capturing and decomposing target species. Moreover, the tunable networks of MOFs allow customization of their chemical functionalities, making them practicable in personal protective equipment and adjustable to dynamic environments. This review paper focuses on experimental and computational studies investigating the removal of CWAs by MOFs, specifically emphasizing the removal of nerve agents (GB, GD, and VX) via hydrolysis and sulfur mustard (HD) via selective photooxidation. Among the different MOFs, zirconium-based MOFs exhibit extraordinary structural stability and reusability, rendering them the most promising materials for the hydrolytic and photooxidative degradation of CWAs. Accordingly, this work primarily concentrates on exploring the intrinsic catalytic reaction mechanisms in Zr-MOFs through first-principles approximations, as well as the design of efficient degradation strategies in the aqueous and solid phases through the establishment of Zr-MOF structure-property relationships. Recent progress in the tuning and functionalization of MOFs is also examined, aiming to enhance practical CWA removal under realistic battlefield conditions. By providing a comprehensive overview of experimental findings and computational insights, this review paper contributes to the advancement of MOF-based strategies for the destruction of CWAs and highlights the potential of these materials to address the challenges associated with chemical warfare.

Combustion of C1 and C2 PFAS: Kinetic modeling and experiments

ABSTRACT A combustion model, originally developed to simulate the destruction of chemical warfare agents, was modified to include C1-C3 fluorinated organic reactions and kinetics compiled by the National Institute of Standards and Technology (NIST). A simplified plug flow reactor version of this model was used to predict the destruction efficiency (DE) and formation of products of incomplete combustion (PICs) for three C1 and C2 per- and poly-fluorinated alkyl substances (PFAS) (CF4, CHF3, and C2F6) and compare predicted values to Fourier Transform Infrared spectroscopy (FTIR)-based measurements made from a pilot-scale EPA research combustor (40–64 kW, natural gas-fired, 20% excess air). PFAS were introduced through the flame, and at post-flame locations along a time-temperature profile allowing for simulation of direct flame and non-flame injection, and examination of the sensitivity of PFAS destruction on temperature and free radical flame chemistry. Results indicate that CF4 is particularly difficult to destroy with DEs ranging from ~60 to 95% when introduced through the flame at increasing furnace loads. Due to the presence of lower energy C-H and C-C bonds to initiate molecular dissociation reactions, CHF3 and C2F6 were easier to destroy, exhibiting DEs >99% even when introduced post-flame. However, these lower bond energies may also lead to the formation of CF2 and CF3 radicals at thermal conditions unable to fully de-fluorinate these species and formation of fluorinated PICs. DEs determined by the model agreed well with the measurements for CHF3 and C2F6 but overpredicted DEs at high temperatures and underpredicted DEs at low temperatures for CF4. However, high DEs do not necessarily mean absence of PICs, with both model predictions and limited FTIR measurements indicating the presence of similar fluorinated PICs in the combustion emissions. The FTIR was able to provide real-time emission measurements and additional model development may improve prediction of PFAS destruction and PIC formation. Implications: The widespread use of PFAS for over 70 years has led to their presence in multiple environmental matrixes including human tissues. While the chemical and thermal stability of PFAS are related to their desirable properties, this stability means that PFAS are very slow to degrade naturally and potentially difficult to destroy completely through thermal treatment processes often used for organic waste destruction. In this applied combustion study, model PFAS compounds were introduced to a pilot-scale EPA research furnace. Real-time FTIR measurements were performed of the injected compound and trace products of incomplete combustion (PICs) at operationally relevant conditions, and the results were successfully compared to kinetic model predictions of those same PFAS destruction efficiencies and trace gas-phase PIC constituents. This study represents a significant potential enhancement in available tools to support effective management of PFAS-containing wastes.

Photo-assisted enhancement performance for rapid detoxification of chemical warfare agent simulants over versatile ZnIn2S4/UiO-66-NH2 nanocomposite catalysts

Constructing versatile materials with self-detoxification properties are highly desired for emergency destruction of chemical warfare agents (CWAs). Herein, we first reported in-situ fabrication of ZnIn2S4/UiO-66-NH2 nanocomposites (ZnInS/UiO) and their application in catalytic detoxification of two CWA simulants. For nerve agent simulant dimethyl 4-nitrophenyl phosphate (DMNP), the optimal ZnInS/UiO-23.9 displayed 5.9 times increase in hydrolysis rate having the turnover frequency (TOF) of 0.0586 s-1 under simulated solar light (SSL), which is superior to the reported UiO-based catalysts. Photo-assisted enhancement in DMNP detoxification was due to photothermal effect of ZnInS and close interfacial contact in ZnInS/UiO heterostructures, facilitating instantaneous heat transfer from ZnInS to UiO catalytic sites. As for mustard gas surrogate 2-chloroethyl ethyl sulfide (CEES), under SSL irradiation for 15 min, ZnInS/UiO-23.9 can eliminate 96.7% of CEES in droplet experiment, being 4.17 and 3.24 times of ZnInS and UiO accordingly. It was ascribed to spatial separation of photoinduced electron-hole pairs and photothermally-assisted charge transfer in ZnInS/UiO composites, improving catalytic activity for CEES detoxification. Besides, the detected products suggested that CEES conversion underwent reductive dechlorination, radical reactions and hydrolysis. This study can be extended to other multifunctional catalysts based on metal-organic frameworks and provides new opportunities for photoassisted enhanced detoxification of CWAs.

Modified-TiO2 Photocatalyst Supported on β-SiC Foams for the Elimination of Gaseous Diethyl Sulfide as an Analog for Chemical Warfare Agent: Towards the Development of a Photoreactor Prototype

In the context of the increase in chemical threat due to warfare agents, the development of efficient methods for destruction of Chemical Warfare Agents (CWAs) are of first importance both for civilian and military purposes. Amongst possible methods for destruction of CWAs, photocatalytic oxidation is an alternative one. The present paper reports on the preparation of Ta and Sn doped TiO2 photocatalysts immobilized on β-SiC foams for the elimination of diethyl sulfide (DES) used as a model molecule mimicking Yperite (Mustard Gas) in gaseous phase. Photo-oxidation efficiency of doped TiO2 catalyst has been compared with TiO2-P25. Here, we demonstrate that the Sn doped-TiO2 with a Polyethylene glycol (PEG)/TiO2 ratio of 7 exhibits the best initial activity (up to 90%) but is deactivates more quickly than Ta doped-TiO2 (40% after 800 min). The activity of the catalysts is strongly influenced by the adsorption properties of the support, as β-SiC foams adsorb DES and other sulfur compounds. This adsorption makes it possible to limit the poisoning of the catalysts and to maintain an acceptable conversion rate even after ten hours under continuous DES flow. Washing with NaOH completely regenerates the catalyst after a firs treatment and even seems to “wash” it by removing impurities initially present on the foams.

Computational simulation of incineration of chemically and biologically contaminated wastes

ABSTRACT This paper describes the modeling approach and example results for a newly introduced computational simulation tool to evaluate waste destruction in thermal incineration systems. The Configured Fireside Simulator (CFS) is a software simulator, originally developed for the Department of Defense to evaluate operations of the chemical demilitarization incinerators processing the chemical warfare agent stockpile of the US. The software was later adapted for use by the U.S. Environmental Protection Agency (EPA) to provide for the ability to run “what if” scenarios of waste streams contaminated with chemical/biological (CB) threat agents in four specific incinerators, including the EPA’s pilot-scale Rotary Kiln Incinerator Simulator (RKIS) facility, as well as three commercial incinerators based on design criteria for actual operating facilities. These commercial incinerators include a Medical/Pathological Waste Incinerator, a Hazardous Waste Burning Rotary Kiln, and a Waste-to-Energy Stoker-type combustor. The CFS uses three-dimensional computational fluid dynamics coupled with detailed chemical kinetic data for destruction of chemical warfare agents, coupled with kinetic data for biological agent destruction derived from bench- and pilot-scale experiments to predict the way agent-containing materials will behave under full-scale combustion conditions in several different incinerator types. The objective of this paper is to describe the CFS software, how it works, and potential applications of this software to real-world situations. This software could be a valuable tool for researchers, regulators, and industry to evaluate potential operating conditions to help guide testing activities and develop operational scenarios for difficult-to-manage waste streams. Although this software has been under development for several years, this paper represents the software’s first introduction to the scientific community in the peer-reviewed literature. Implications: Adapting the Configured Fireside Simulator that was originally developed for the Department of Defense to evaluate operations of the chemical demilitarization incinerators processing the chemical warfare agent stockpile of the US to provide for the ability to run “what if” scenarios on civilian waste streams contaminated with CB agents is a useful tool for national preparedness. Such a model could be used in planning and response efforts to provide a better understanding of incineration capacity, development of feed strategies, and assessment of throughput limitations for CB incidents as well as other difficult-to-test waste streams and contaminants.

Decavanadate-based clusters as bifunctional catalysts for efficient treatment of carbon dioxide and simulant sulfur mustard

Reutilization of carbon dioxide (CO2) and destruction of chemical warfare agents (CWAs) at ambient conditions are deemed as two of the crucial challenges to steer toward a more sustainable future because they can cause great hazard to human beings and environment. Design of stable, selective and powerful catalysts for multi-functional catalysis is highly desirable yet largely unmet. In this work, a series of novel decavanadate-based transition metal clusters (POVs-TM, compounds 1–5) have been reported. Compounds 1–5 possess decavanadate-centered structures in which one decavanadate cluster bridged two bridged or free transition metal units. Decavanadate unit, serving as redox center can construct bifunctional catalysis platform with transition metal. Thus-obtained clusters can serve as powerful bifunctional catalysts in both cycloaddition of CO2 and degradation of sulfur mustard simulant. Specially, compound 1 presented high performance (conv. up to 99.4 %, sele. up to 99.5 %) in chemical fixation of CO2 into valuable cyclic carbonates with simulated flue gas as the gas resource. Besides, compound 3 performed superior efficiency (conv. 98.9 %, sele. 98.7 %) than other catalysts in the degradation of sulfur mustard simulant under ambient conditions. These dual-function validated POVs-TM clusters hold much promise in the exploration of novel catalysts for applications like continuous catalytic or flow bed reactions.

Synthesis of macroscopic monolithic metal–organic gels for ultra-fast destruction of chemical warfare agents

The potential threat that has originated from chemical warfare agents (CWAs) has promoted the development of advanced materials to enhance the protection of civilian and military personnel. Zr-based metal–organic frameworks (Zr-MOFs) have recently been demonstrated as excellent catalysts for decomposing CWAs, but challenges of integrating the microcrystalline powders of Zr-MOFs into monoliths still remain. Herein, we report hierarchically porous monolithic UiO-66-X xerogels for the destruction of CWAs. We found that the UiO-66-NH2 xerogel with a larger pore size and a higher surface area than the UiO-66-NH2 powder possessed better degradability of 2-chloroethyl ethyl sulfide (2-CEES), which is a sulfur mustard simulant. These UiO-66-X xerogels exhibit outstanding performance for decomposing CWAs. The half-lives of vesicant agent sulfur mustard (HD) and nerve agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) are as short as 14.4 min and 1.5 min, respectively. This work is, to the best of our knowledge, the first report on macroscopic monolithic UiO-66-X xerogels for ultrafast decomposition of CWAs.

Modeling of Diffusion of Acetone in UiO-66

Highly porous zirconium-based metal–organic frameworks (MOFs) have been widely studied as materials for sorption and destruction of chemical warfare agents (CWAs). It is important to understand the diffusion of CWAs, their reaction products, and environmental molecules through MOFs to utilize these materials for protection against CWA threats. As a first step toward this goal, we study adsorption and diffusion of acetone in pristine UiO-66. We have chosen to study UiO-66 because it has been demonstrated to be effective for destruction of CWAs and simulants; we use acetone because it is a prototypical polar organic molecule small enough to be expected to diffuse fairly rapidly through nondefective UiO-66. We specifically examine the impact of framework flexibility and hydrogen bonding between acetone and the OH groups on the nodes of the framework on the diffusivity of acetone. We find that inclusion of flexibility is essential for meaningful predictions of diffusion of acetone. We have identified the dynamics of the three linkers making up the triangular window between adjacent pores as the critical factor in controlling diffusion of acetone. We demonstrate from experiments and first-principles calculations that acetone readily hydrogen bonds to UiO-66 framework OH groups. We have modified the classical potential for UiO-66 to accurately model the framework–acetone hydrogen bonds, which are not accounted for in many MOF potentials. We find that hydrogen bonding decreases the diffusivity by about 1 order of magnitude at low loading and about a factor of 3 at high loading. Thus, proper accounting of hydrogen bonding and framework flexibility are both critical for obtaining physically realistic values of diffusivities for acetone and similar-sized polar molecules in UiO-66.

Photothermally Enhanced Detoxification of Chemical Warfare Agent Simulants Using Bioinspired Core-Shell Dopamine-Melanin@Metal-Organic Frameworks and Their Fabrics.

Self-detoxifying materials capable of both capture and destruction of chemical warfare agents (CWAs) are highly desirable for efficient personal protection and safe handling of contaminated materials. Developing new strategies to improve CWA removal efficiency of these materials is highly relevant to CWA purification technology. Herein, we present novel photothermally enhanced catalytic detoxification of CWA simulants and its application in self-detoxifying gas filters. The material design features a well-defined core-shell nanostructure (CSN) consisting of an inner photothermal material and an outer microporous catalyst. As a demonstration, the CSN was obtained by growing a Zr-based metal-organic framework (MOF), UiO-66-NH2, onto bioinspired dopamine-melanin (Dpa) nanoparticles via heterogeneous nucleation induced by metal chelation. The resultant Dpa@UiO-66-NH2 CSN has increased the turnover frequency (TOF) of a nerve agent simulant, 4-nitrophenyl phosphate (DMNP), by 2.9- and 1.7-fold in the presence of NIR laser and simulated solar light, respectively. Further incorporation of Dpa@UiO-66-NH2 CSNs into polymer fibers by electrospinning has led to an even greater photothermal enhancement effect (5.8- and 3.2-fold TOF increase), achieving a faster DMNP degradation rate than the corresponding pure MOF powder for the first time and the shortest half-life of DMNP (1.8 min) among reported MOF-based self-detoxifying fabrics. The significant photothermal enhancement in the detoxification ability of Dpa@UiO-66-NH2 fabrics is attributed to the instantaneous heat transfer from the photothermal core to the catalytic shell and effective heat retention enabled by the surrounding polymer matrix. The Dpa@UiO-66-NH2 fabrics can be easily prepared on a large scale and demonstrate efficient protection against DMNP aerosols as stand-alone gas filters. This strategy of photothermally enhanced catalytic detoxification can be feasibly extended to other catalytic detoxification systems and holds promise for next-generation gas masks.

Sn-doped and porogen-modified TiO2 photocatalyst for solar light elimination of sulfure diethyle as a model for chemical warfare agent

In the context of the increase in chemical threat due to warfare agents, the development of efficient methods for destruction of Chemical Warfare Agents are of first importance both for civilian and military purposes. Here, we demonstrate that optimized Sn-TiO2 doped and PEG-modified photocatalysts allow increased and high performances under UVA and solar-light irradiations leading to total elimination of highly contaminated environments containing Diethylsulfide (DES) used as a model molecule mimicking Yperite (Mustard Gas). It has been shown that Sn doping induces significant modifications on the structural, morphological, surface, electronic and optical properties of TiO2. For example, the addition of 1% Sn increases significantly the surface area from 30 to 80 m2/g and decreases the particle size, while Sn-doping results in a reduction of the anatase band-gap from 3.2 to 2.95 eV. Total DES elimination could be reached for 90 and 120 min under continuous contaminant flux under UVA and solar light activation, respectively accompanied with limited deactivation phenomenon. Correlations between the resulting physico-chemical properties of the doped and PEG-modified materials and the photocatalytic activities were carried out. The results open up extremely promising way for the decontamination of highly contaminated environments containing real warfare agents under UVA but also under solar light illumination.

Insights into Catalytic Hydrolysis of Organophosphate Warfare Agents by Metal–Organic Framework NU-1000

Metal–organic frameworks (MOFs) have been reported to be versatile catalysts because of their amenability to modular design and tunability. Recently, a series of zirconium-based MOFs have been used to catalyze the hydrolytic destruction of chemical warfare agents (CWAs) that contain phosphate ester bonds. Here, we adopt density functional theory calculations to study the hydrolysis of the CWA simulant methylparaoxon on the Zr-based MOF NU-1000. Our calculated energy barriers are in quantitative agreement with previous experimental kinetics data. Comparison between uncatalyzed aqueous hydrolysis and the MOF-catalyzed reaction reveals the origin of the catalytic effects of NU-1000 and shows a resemblance to enzymatic catalysis of similar reactions. The effect of node distortion on the catalytic mechanism is also examined, and the results are consistent with experimental findings, where the distorted node of NU-1000 shows an increase in the rate of methylparaoxon hydrolysis compared to the completely hydrate...

Destruction of chemical warfare surrogates using a portable atmospheric pressure plasma jet

Today’s reality is connected with mitigation of threats from the new chemical and biological warfare agents. A novel investigation of cold plasmas in contact with liquids presented in this paper demonstrated that the chemically reactive environment produced by atmospheric pressure plasma jet (APPJ) is potentially capable of rapid destruction of chemical warfare agents in a broad spectrum. The decontamination of three different chemical warfare agent surrogates dissolved in liquid is investigated by using an easily transportable APPJ. The jet is powered by a kHz signal source connected to a low-voltage DC source and with He as working gas. The detailed investigation of electrical properties is performed for various plasmas at different distances from the sample. The measurements of plasma properties in situ are supported by the optical spectrometry measurements, whereas the high performance liquid chromatography measurements before and after the treatment of aqueous solutions of Malathion, Fenitrothion and Dimethyl Methylphosphonate. These solutions are used to evaluate destruction and its efficiency for specific neural agent simulants. The particular removal rates are found to be from 56% up to 96% during 10 min treatment. The data obtained provide basis to evaluate APPJ’s efficiency at different operating conditions. The presented results are promising and could be improved with different operating conditions and optimization of the decontamination process.

Biotechnological Methods of Destruction of Chemical Warfare Agents and Their Detoxication Products

The work presents an overview of the main results of experimental and theoretical researches made by the Federal State Budgetary Establishment «27 Scientific Centre» of the Ministry of Defence of the Russian Federation together with other scientific organizations and institutions in 1989–2014 in the sphere of the development of biocatalysts, and biotechnological methods of destruction of chemical warfare agents (organophosphorus agents) and the products of their detoxication, including the reactionary masses, obtained during the industrial destruction of chemical weapons. The article shows that the methods of the remediation of soil and purification of water with the usage of microorganisms-destructors or their consortiums and their enzymes can be used for the neutralization of any detoxication products of chemical warfare agents, obtained by the usage of different technologies of chemical neutralization. This indicates the possibility of environmentally friendly neutralization and detoxification of considerable volume and concentrations of agents as well as large territories at the sites of former production, storage and destruction of chemical warfare agents. These eco-friendly and safe neutralization and detoxification technologies can be based on microbial biocatalytic processes. The authors assert that on the basis of the analysis mentioned above it is possible to substantiate the choice of the enzymes and the strains with high destruction ability and tolerance towards toxic agents, to elaborate the technological schemes of the production of the eco-biopreparations (biocatalysts) on the basis of the enzymes and microorganizms-destructors and to develop the technological schemes of the remediation of soil and purification of water using biocatalyst-enzymes and immobilized bacterial cells

Omar K. Farha

Angewandte Chemie International EditionVolume 56, Issue 13 p. 3420-3420 Author ProfileFree Access Omar K. Farha First published: 11 October 2016 https://doi.org/10.1002/anie.201608945Citations: 2AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract “When I was eighteen I wanted to be a pilot. The principal aspect of my personality is pragmatic optimism ...” This and more about Omar K. Farha can be found on page 3420. Omar K. Farha The author presented on this page has recently published his 10th article in Angewandte Chemie in the last 10 years: “Design and Synthesis of a Water-Stable Anionic Uranium-Based Metal–Organic Framework (MOF) with Ultra Large Pores”: P. Li, N. A. Vermeulen, X. Gong, C. D. Malliakas, J. F. Stoddart, J. T. Hupp, O. K. Farha, Angew. Chem. Int. Ed. 2016, 55, 10358; Angew. Chem. 2016, 128, 10514. Position: Research Professor of Chemistry, Northwestern University; Distinguished Adjunct Professor, King Abdulaziz University; President, NuMat Technologies E-mail: o-farha@northwestern.edu Homepage: http://sites.northwestern.edu/omarkfarha/ Education: 2002 Undergraduate degree, University of California, Los Angeles (UCLA) 2006 PhD supervised by M. Frederick Hawthorne, UCLA 2007–2009 Postdoctoral position with Joseph T. Hupp, Northwestern University Awards: 2015 Royal Society of Chemistry Environment, Sustainability and Energy Division Early Career Award; 2016 Kavli Emerging Leader Lecturer, American Chemical Society Current research interests: Rational design of metal–organic frameworks (MOFs) and porous organic polymers for sensing, catalysis, storage, separations, and light harvesting Hobbies: Traveling, soccer When I was eighteen I wanted to be a pilot. The principal aspect of my personality is pragmatic optimism. My favorite drink is a good cup of coffee! My first experiment was an acid/base titration and pKa calculation in a general chemistry lab course. In a spare hour, I play soccer with my son and have a tea party with my daughter. My favorite quote is “If it's important you'll find a way. If it's not, you'll find an excuse” (Ryan Blair). My favorite time of day is dinner time with my family. I get advice from my wife, friends, and colleagues. I advise my students to be curious, work hard, and have a goal. The secret of being a successful scientist is always be hungry for more and don't apologize for it. My science “heroes” are Françoise Barré-Sinoussi, Albert Einstein, Richard Feynman, and Christa McAuliffe. If I had one year of paid leave I would write a book while eating pizza and gelato in Italy. My motto is don't take opportunities for granted. My 5 top papers: References 1“Toward Design Rules for Enzyme Immobilization In Hierarchical Mesoporous Metal–Organic Frameworks”: P. Li, J. A. Modica, A. J. Howarth, E. Vargas, L. Peyman, Z. Moghadam, R. Q. Snurr, M. Mrksich, J. T. Hupp, O. K. Farha, CHEM 2016, 1, 154. (The design rules we have learned in this work can pave the way to making better enzyme/MOF catalysts.) 2“Selective Photooxidation of a Mustard-Gas Simulant Catalyzed by a Porphyrinic Metal–Organic Framework”: Y. Liu, A. J. Howarth, J. T. Hupp, O. K. Farha, Angew. Chem. Int. Ed. 2015, 54, 9001; Angew. Chem. 2015, 127, 9129. (Utilization of cheap and simple technology for decontamination purposes.) 3“Destruction of chemical warfare agents using metal–organic frameworks”: J. E. Mondloch et al., Nat. Mater. 2015, 14, 512. (By understanding how a catalyst works in this work, we made a better one soon after.) 4“Vapor-Phase Metalation by Atomic Layer Deposition in a Metal–Organic Framework”: J. E. Mondloch et al., J. Am. Chem. Soc. 2013, 135, 10294. (A synthetic strategy that involved the combination of two fields.) 5“Supercritical Processing as a Route to High Internal Surface Areas and Permanent Microporosity in Metal–Organic Framework Materials”: P. Nelson, O. K. Farha, K. L. Mulfort, J. T. Hupp, J. Am. Chem. Soc. 2009, 131, 458. (Utilization of cheap technology to advance the field of MOFs.) Citing Literature Volume56, Issue13March 20, 2017Pages 3420-3420 ReferencesRelatedInformation

Ta-doped TiO2 as photocatalyst for UV-A activated elimination of chemical warfare agent simulant

In the context of the increase in chemical threat due to warfare agents in terms of terrorist chemical attacks as well as of accumulation in stockpiles, the development of efficient methods for destruction of Chemical Warfare Agents (CWA) is of first importance for both civilian and military purposes. Here, we present innovative Ta–TiO2 doped photocatalysts able to lead to the total elimination of highly contaminated environments containing diethylsulfide (DES) used as a simulant of CWA, namely of Yperite (Mustard Gas). It has been shown that the Ta doping could induce significant modifications on the structural, morphological, surface, electronic and optical properties of TiO2. Optimization of the Ta loading in the doped material as well as of the calcination temperature led to excellent performances toward the elimination of high concentrations of DES (1200ppmv, i.e. 5g/m3 of air) contained in air under UV-A irradiation. Total DES elimination could be reached for 100min under continuous contaminant flux before deactivation and the conversion maintained to 80% of degradation after 200min. Correlations between the resulting physicochemical properties of the doped material and the photocatalytic activity have been proposed and reaction mechanism pathways have been suggested. The results open up an extremely promising way for the use of Ta-doped TiO2 photocatalysts for the decontamination of highly contaminated environments containing real warfare agents under UV-A irradiation but also under visible or solar light illumination.

Update 1 of: Destruction and Detection of Chemical Warfare Agents.

Update 1 of: Destruction and Detection of Chemical Warfare Agents.

Cerium oxide for the destruction of chemical warfare agents: A comparison of synthetic routes

Four different synthetic routes were used to prepare active forms of cerium oxide that are capable of destroying toxic organophosphates: a sol–gel process (via a citrate precursor), homogeneous hydrolysis and a precipitation/calcination procedure (via carbonate and oxalate precursors). The samples prepared via homogeneous hydrolysis with urea and the samples prepared via precipitation with ammonium bicarbonate (with subsequent calcination at 500°C in both cases) exhibited the highest degradation efficiencies towards the extremely dangerous nerve agents soman (O-pinacolyl methylphosphonofluoridate) and VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate) and the organophosphate pesticide parathion methyl. These samples were able to destroy more than 90% of the toxic compounds in less than 10min. The high degradation efficiency of cerium oxide is related to its complex surface chemistry (presence of surface OH groups and surface non-stoichiometry) and to its nanocrystalline nature, which promotes the formation of crystal defects on which the decomposition of organophosphates proceeds through a nucleophilic substitution mechanism that is not dissimilar to the mechanism of enzymatic hydrolysis of organic phosphates by phosphotriesterase.

Destruction of chemical warfare agents using metal-organic frameworks.

Chemical warfare agents containing phosphonate ester bonds are among the most toxic chemicals known to mankind. Recent global military events, such as the conflict and disarmament in Syria, have brought into focus the need to find effective strategies for the rapid destruction of these banned chemicals. Solutions are needed for immediate personal protection (for example, the filtration and catalytic destruction of airborne versions of agents), bulk destruction of chemical weapon stockpiles, protection (via coating) of clothing, equipment and buildings, and containment of agent spills. Solid heterogeneous materials such as modified activated carbon or metal oxides exhibit many desirable characteristics for the destruction of chemical warfare agents. However, low sorptive capacities, low effective active site loadings, deactivation of the active site, slow degradation kinetics, and/or a lack of tailorability offer significant room for improvement in these materials. Here, we report a carefully chosen metal-organic framework (MOF) material featuring high porosity and exceptional chemical stability that is extraordinarily effective for the degradation of nerve agents and their simulants. Experimental and computational evidence points to Lewis-acidic Zr(IV) ions as the active sites and to their superb accessibility as a defining element of their efficacy.

A mathematical theory of the supercritical state serving as an effective means of destruction of chemical warfare agents

It is well known that the supercritical state of a gas has great dissolving capacity. In this paper, the mathematical reason for this phenomenon is studied in great detail.