Degradation Of Sulfur Mustard Research Articles

Plasma jet decontamination of sulfur mustard and its analogues in water by oxidation effect

Atmospheric pressure plasma jet (APPJ), as an emerging clean and efficient technology, has been found a great potential for chemical warfare agents (CWAs) decontamination. In this study, we first proposed APPJ for the degradation of sulfur mustard (HD) and its surrogate 2-chloroethyl ethyl sulfide (2-CEES) in water. Under optimal conditions, the degradation efficiency of 2-CEES and HD reached 100 % after 5 min or 6 min plasma treatment. The degradation products of 2-CEES and HD were mainly non-toxic alcohols or low toxic sulfones, which can be degraded and converted into some small molecules (HCl, SO2, or CO2) under further plasma treatment. We then identified two dominant short-lived reactive species (·OH and 1O2) and long-lived reactive molecule (H2O2) and distinguished the effect of these three active particles during the degradation process of 2-CEES in water. This work provides detailed evidence of a novel decontamination strategy for HD and 2-CEES.

Chloroperoxidase-catalyzed oxidative degradation of sulfur mustard

As a natural heme protein catalyzing the oxidation of sulfides to sulfoxides without sulfone formation, chloroperoxidase (CPO) is well suited for the degradation of sulfur mustard (HD), a persistent chemical warfare agent that has been widely disposed since World War II and continuously leaks into aquatic environments. Herein, we report the first systematic investigation of CPO-catalyzed degradation of HD and the potential application of CPO in destroying chemical weapons under mild conditions. The related Michaelis–Menten parameters (Km=0.17 mM, Vmax=0.06 mM s−1 (R2 =0.935), and kcat= 2717 s−1) indicated nearly a prominent enzymatic efficiency. Under optimal conditions, 80% of HD was transformed to bis(2-chloroethyl) sulfoxide as identified by mass spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. Other metabolites were also generated during the decontamination process. A plausible oxidation mechanism was proposed based on the degradation products, NMR titration experiments, and molecular dynamics simulations. CPO also promoted the degradation of other chemical weapon agents, namely, Lewisite (L) and venomous agent X (VX), thereby exhibiting a broad substrate scope. The high potential of the developed system for the decontamination of aquatic environments was demonstrated by the successful hatching of zebrafish embryos after HD degradation and the survival of zebrafish (Danio rerio, AB strain) larvae after the degradation of Agent Yellow (L+HD).

Studying adsorption and detoxification of sulfur mustard chemical warfare onto ZnO nanostructures

Sulfur mustard is a strong vesicant, leading to severe skin damages as well as eye blistering and may lead to death if inhaled. Unfortunately, there are no effective treatments for mustard-induced injury. Hence, there is considerable attention in the development of materials that can absorb or detoxify mustard gas. In the first part of this report, detoxification of sulfur mustard is performed on the synthetic ZnO nanosheets. The intended ZnO nanostructure is prepared via a simple and efficient method and characterized by means of FT-IR, XRD, FESEM, and XPS to confirm formation of the desired nanosheets. Then, detoxification and degradation of sulfur mustard is carried out on the prepared ZnO nanostructures at room temperature and a good rate for sulfur mustard detoxification was attained at the initial stages of the reaction (1−12 h) with a rate constant of 0.081 h−1 and a half-life of 8.4 h. At the second part of the present study, the density functional calculations including B3LYP and wB97XD are used to monitor the adsorption of this toxic material on the surface of various ZnO nanoclusters (ZnONCs). The values of adsorption energy of mustard gas are determined in the range of about −16 to −54 kcal/mol with enthalpies in the range of about −15 to-51 kcal/mol and the Gibbs free energies in the range of −3 to −28 kcal/mol at 298 K based on B3LYP level of theory. The geometry parameters are calculated for all geometries by consideration of the charge analysis and frontier molecular orbitals. Findings revealed that these systems are useful chemical sensors for sulfur mustard. Moreover, it is found that the CCL-ZnONS can effectively interact with this material and modifies the sensitivity of zinc oxide towards this agent.

Combining Two into One: A Dual-Function H5PV2Mo10O40@MOF-808 Composite as a Versatile Decontaminant for Sulfur Mustard and Soman.

Due to the unpredictable nature of a battlefield environment, in the simultaneous degradation of sulfur mustard and nerve agents it is preferable to use just one decontaminant. Herein, the new composite HPVMo@MOF-808 (HPVMo = H5PV2Mo10O40) was deliberately synthesized via a simple impregnation method and thoroughly characterized. The results showed that the decontamination rate of the composites (30-40 mg) with optimal HPVMo loadings for HD (4 μL) and GD (4 μL) under ambient conditions was 97.2% (within 120 min) and 90.8% (within 30 min), respectively. Due to the combinational/synergistic effect of MOF-808 and encapsulated homogeneously dispersed HPVMo, the composite can very efficiently oxidize HD to nontoxic products in a single system, while retaining the inherent excellence of MOF-808 in hydrolytically degrading GD. The decontamination process was found to follow first-order reaction kinetics, and the rate constant and half-life of the composite for HD and GD were 0.0231 min-1, 30.13 min and 0.0795 min-1, 8.72 min, respectively. In addition, experimental results in guinea pigs and Kunming mice used as animal models showed that the composite provided effective skin protection against HD and GD, showing great potential for application in skin decontamination and protection.

Photoelectrocatalytic degradation of vesicant agent using Eu/ZnO/pPy nanocomposite

Herein, we demonstrate a nanocomposite material Eu/ZnO/pPy for enhanced performance in photoelectrocatalytic degradation of chemical warfare agent sulphur mustard (SM) at ambient conditions which is growing concern of the Scientific Community amidst the current climate of terrorism. Eu/ZnO/pPy was electrochemically prepared on Au electrode at ambient conditions and was used for electrocatalytic reductive elimination of chloride from SM and results indicated one electron involvement process for the cleavage of the carbon-chloride bond. Surface morphology of Eu/pPy, ZnO/pPy and Eu/ZnO/pPy composites were characterized by SEM and confirmed the formation of the nanoparticles and nanorods on the modified electrode which leads to provide more surface area for the reductive elimination reaction. The elemental composition, functional groups and phase of materials on the modified electrode were deduced using EDX, Raman spectroscopy and XRD, respectively. Eu/ZnO/pPy/Au electrode was utilized for the photoelectrocatalytic degradation of SM as it exhibit excellent electrocatalytic activity and degradation products were analyzed by GC-MS. In the reductive elimination of SM, the following parameters were deduced (i) heterogeneous rate constant (0.127 s−1), (ii) transfer coefficient (0.32) and (iii) number of electron involved (1.0). The enhanced photoelectrocatalytic capability of this nanocomposite could serve as a novel and promising catalyst in defence and environmental applications.

Significant enhancement in hydrolytic degradation of sulfur mustard promoted by silver nanoparticles in the Ag NPs@HKUST-1 composites

The Ag NPs@HKUST-1 composites have been successfully prepared with different loading amounts of silver nanoparticles in HKUST-1 featuring a three-dimensional system of channels constructed by benzene-1,3,5-tricarboxylate and dimeric cupric units by a simple one-pot hydrothermal method, and characterized by various microscopy and spectroscopy analysis techniques. The average particle size of Ag NPs increased with the increase of the loading amount of Ag NPs. The experimental results showed that the degradation of sulfur mustard (HD) under ambient conditions followed pseudo-first order reaction kinetics. Additionally, the optimized Ag NPs@HKUST-1 (wherein Ag is l6.67 wt%) exhibited the highest degradation efficacy with an equilibrium rate constant and half-life for HD of 0.0450 min−1 and 15.34 min, respectively. These values were significantly higher than those for pure HKUST-1 with an equilibrium rate constant and half-life for HD of 0.0168 min-1 and 41.29 min, under the same experimental conditions. Gas chromatography-mass spectrometry (GC–MS) analysis on the product of 2-chloroethylethyl sulfide (2-CEES) degraded by Ag NPs@HKUST-1 showed that 2-hydroxyethyl ethyl sulfide (2-HEES) is the sole product, indicating that the remarkable enhancement of the degradation of HD must be due to the Ag NPs, which can promote hydrolysis of the chemical war agent in the composite.

Evaluation of carbon aerogel-based solid-phase extraction sorbent for the analysis of sulfur mustard degradation products in environmental water samples

In this study, SPE method using a carbon aerogel(CA)-based sorbent was developed and evaluated for the simultaneous extraction of sulfur mustard (HD) degradation products from environmental water samples. Applied CAs proved to be very promising materials for use as SPE sorbents, due to their high porosity, very low density and a large specific surface area. 10 degradation products of HD, both aliphatic and cyclic (thiodiglycol (TDG), TDG sulfoxide, TDG sulfone, 3,5-dithia-1,7-heptanediol, 3,6-dithia-1,8-octanediol, 1,4-thioxane, 1,3-dithiolane, 1,4-dithiane, 1,2,5-trithiepane, and 1,4,5-oxadithiepane) were extracted on a CA-based SPE cartridge. The concentrations of target analytes in the eluate were determined by HPLC-DAD and CE-DAD. Several parameters affecting the extraction efficiency, including the kind and volume of the eluting solvent, sample loading flow rate, volume and ionic strength as well as the reusability of the cartridge, were investigated and optimized to achieve the best performance for the analytes. A series of quantitative parameters such as linear range, coefficient of determination, LOD, LOQ and precision were examined under the optimized conditions. High sensitivity (LODs 0.17–0.50 μM) and high precision (intraday RSD = 2.0–7.7% and interday RSD = 2.7–9.9%) for all the analytes were achieved. The performance of the CA-based sorbent was compared with that of commonly used SPE sorbents. Applied for the analysis of spiked pore water samples collected from the Bornholm Basin, one of the largest chemical warfare dumping sites in the Baltic Sea, the proposed method allowed high SPE recoveries of all the analytes ranging from 83.5 to 99.7% to be obtained.

Glutathione as an antidote for sulfur mustard poisoning: Mass spectrometric investigations of its potency as a chemical scavenger

The banned chemical warfare agent sulfur mustard (SM) still represents a serious threat to civilians and military personnel. Therefore, identification of antidotes and scavengers is of high concern. One promising substance is glutathione (GSH). GSH is known to mitigate symptoms of SM poisoning in vitro and in vivo. However, the mechanism of action remains unclear with respect to physiological impact as well as chemical scavenging by reaction between GSH and SM. Therefore, a novel in vitro method was used to characterize the scavenging potential of GSH. Accordingly, alkylation of human serum albumin (HSA), which represents an established biomarker for SM intoxication, was used as a measure for remaining SM. Coincubation of GSH and SM in human serum was performed, and time-dependent degradation of SM was monitored in the presence and absence of GSH. Protein-derived and small molecular reaction products between GSH, HSA, and SM were analyzed using microbore liquid chromatography-electrospray ionization high-resolution tandem-mass spectrometry. Although covalent modification of GSH by SM was observed, measurements clearly documented no significant reduction of SM concentration in the presence of GSH. Accordingly, beneficial therapeutic mechanisms of GSH in the case of SM poisoning would appear to be based on physiological effects than on chemical scavenging.

Suppressed swimming activity in Zebrafish (Danio rerio) exposed to 1,4,5-oxadithiepane, a sulphur mustard degradation product

This rapid communication presents novel data on the ecotoxicity of the cyclic sulphur mustard degradation compound, 1,4,5-oxadithiepane. Groups of adult male Zebrafish (Danio rerio) were exposed to 1,4,5-oxadithiepane at 40.3 ± 2.9 μg L-1, 133.3 ± 6.7 μg L-1 and 1533.3 ± 266.7 μg L-1, respectively. After 14 days of exposure, fitness and lethality were accessed and the swimming behaviour of the Zebrafish was measured by an automated video tracking system. The average swimming velocity was decreased significantly from 40.4 ± 2.5 mm s-1 in the control group to 31.8 ± 1.6 mm s-1 in the low dose. The low and high doses demonstrated suppressed average velocities, partly due to elevated immobile periods (rest time). Thus, at 40.3 ± 2.9 μg L-1 and 1533.3 ± 266.7 μg L-1 both parameters were significantly different from the control group. No adverse effects were found at the 1533.3 ± 266.7 μg L-1 treatment level and no lethality, associated with the toxic properties of 1,4,5-oxadithiepane, was observed during the 14 days of exposure suggesting a 14 days No-Observed-Effect-Concentration above 1533.3 μg L-1.

Enhanced thermal degradation of 2,2′-dichlorodiethyl sulfide (sulfur mustard, HD) with the presence of metal oxides

GRAPHICAL ABSTRACT

Rapid and complete degradation of sulfur mustard adsorbed on M/zeolite-13X supported (M = 5 wt% Mn, Fe, Co) metal oxide catalysts with ozone

Complete degradation of sulfur mustard adsorbed over M/zeolite-13X (M = 5 wt% Mn, Fe, Co) catalysts using ozone gas under ambient conditions.

Acute toxicity of sea-dumped chemical munitions: luminating the environmental toxicity of legacy compounds

As a result of the disarmament of Germany after the Second World War, 65,000 tons of chemical munitions were dumped in the Baltic Sea. Approximately 13,000 tons containing chemical warfare agents (CWAs) of which 11,000 tons were dumped in the Bornholm Basin east of Bornholm. This paper addresses the ecotoxicity of compounds actually present in the Bornholm dumpsite by obtaining novel acute ecotoxicity data. EC50 values were successfully obtained for 12 CWAs from acute tests using Allivibrio fischeri (Microtox™). The three most toxic compounds were α-chloroacetophenone, 2-chlorovinylarsonic acid and 1,2,5-trithiepane having EC50 values of 11.20, 31.20 and 1170 μg L−1, respectively. A. fischeri demonstrated hormesis when exposed to triphenylarsine and triphenylarsine oxide at concentrations of 100 and 50 mg L−1, respectively. Four different mixtures were assessed including compounds which were dissolvable; a mixture of sulphur mustard degradation products, a mixture of the three most toxic sulphur mustard compounds, a mixture of organoarsenical degradation products and a mixture of all compounds. The mixtures deviate by a factor of 1.5–2.5 from the prediction of the concentration addition model and hence, the mixtures demonstrate no sign of synergism or antagonism. The compounds presented in this study are mainly CWA.

Development of a dynamic headspace gas chromatography–mass spectrometry method for on-site analysis of sulfur mustard degradation products in sediments

Sampling teams performing work at sea in areas where chemical munitions may have been dumped require rapid and reliable analytical methods for verifying sulfur mustard leakage from suspected objects. Here we present such an on-site analysis method based on dynamic headspace GC–MS for analysis of five cyclic sulfur mustard degradation products that have previously been detected in sediments from chemical weapon dumping sites: 1,4-oxathiane, 1,3-dithiolane, 1,4-dithiane, 1,4,5-oxadithiephane, and 1,2,5-trithiephane. An experimental design involving authentic Baltic Sea sediments spiked with the target analytes was used to develop an optimized protocol for sample preparation, headspace extraction and analysis that afforded recoveries of up to 60–90%. The optimized method needs no organic solvents, uses only two grams of sediment on a dry weight basis and involves a unique sample presentation whereby sediment is spread uniformly as a thin layer inside the walls of a glass headspace vial. The method showed good linearity for analyte concentrations of 5–200ng/g dw, good repeatability, and acceptable carry-over. The method's limits of detection for spiked sediment samples ranged from 2.5 to 11μg/kg dw, with matrix interference being the main limiting factor. The instrumental detection limits were one to two orders of magnitude lower. Full-scan GC–MS analysis enabled the use of automated mass spectral deconvolution for rapid identification of target analytes. Using this approach, analytes could be identified in spiked sediment samples at concentrations down to 13–65μg/kg dw. On-site validation experiments conducted aboard the research vessel R/V Oceania demonstrated the method's practical applicability, enabling the successful identification of four cyclic sulfur mustard degradation products at concentrations of 15–308μg/kg in sediments immediately after being collected near a wreck at the Bornholm Deep dumpsite in the Baltic Sea.

Mass spectral studies on vinylic degradation products of sulfur mustards under gas chromatography/mass spectrometry conditions.

Sulfur mustards are a class of vesicant chemical warfare agents that rapidly degrade in environmental samples. The most feasible degradation products of sulfur mustards are chloroethyl vinylic compounds and divinylic compounds, which are formed by the elimination of one and two HCl molecules from sulfur mustards, respectively. The detection and characterization of these degradation products in environmental samples are an important proof for the verification of sulfur mustard usage. In this study, we synthesized a set of sulfur mustard degradation products, i.e., divinylic compounds (1-7) and chloroethyl vinylic compounds (8-14), and characterized using gas chromatography/mass spectrometry (GC/MS) under electron ionization (EI) and chemical ionization (CI) (methane) conditions. The EI mass spectra of the studied compounds mainly included the fragment ions that resulted from homolytic cleavages with or without hydrogen migrations. The divinylic compounds (1-7) showed [M-SH](+) ions, whereas the chloroethylvinyl compounds (8-14) showed [M-Cl](+) and [M-CH2CH2Cl](+) ions. Methane/CI mass spectra showed [M+H](+) ions and provided molecular weight information. The GC retention index (RI) values were also calculated for the studied compounds. The EI and CI mass spectral data together with RI values are extremely useful for off-site analysis for the verification of the chemical weapons convention and also to participate in official Organization for the Prohibition of Chemical Weapons proficiency tests.

Sulphur doped nano TiO2: Synthesis, characterization and photocatalytic degradation of a toxic chemical in presence of sunlight

Sunlight assisted photocatalytic degradation of sulphur mustard was studied on sulphur doped titania nanocatalyst. The data obtained on doped titania nanocatalyst was compared with that of undoped and commercial TiO2 nanocatalysts. Sulphur doped titania nanocatalyst exhibited better activity than undoped, and commercial titania nanocatalysts towards the photocatalytic degradation of sulphur mustard. Sulphur doped TiO2 nanocatalyst degraded 100% of sulphur mustard within 120 min. Whereas, it took 240 min for undoped TiO2 nanocatalyst, and 420 min for commercial TiO2 nanocatalyst to completely degrade sulphur mustard. Sulphur mustard degraded to acetaldehyde, carbon dioxide, disulfide, sulfoxide and sulfone of sulphur mustard, chloro ethyl vinyl sulfide, chloro ethyl vinyl sulfoxide, etc, due to photocatalysis facilitated by doped and undoped TiO2 nanocatalysts. Reduced band gap energy and increased visible light absorbance contributed to superior photocatalytic activity of S doped TiO2 nanocatalyst relative to other ones in the presence of sunlight.

Comparison of Various Mesoporous Transition Metal Ion Doped Titania Nanocatalysts for Sunlight Assisted Photocatalytic Degradation of Sulfur Mustard

Comparison of Various Mesoporous Transition Metal Ion Doped Titania Nanocatalysts for Sunlight Assisted Photocatalytic Degradation of Sulfur Mustard

Mesoporous Vanadium Ion Doped Titania Nanocatalysts for the Photocatalytic Degradation of Sulfur Mustard

Mesoporous Vanadium Ion Doped Titania Nanocatalysts for the Photocatalytic Degradation of Sulfur Mustard

A simple degradation method for sulfur mustard at ambient conditions using nickelphthalocyanine incorporated polypyrrole modified electrode

Electrocatalytic degradation of sulfur mustard (SM) was studied using a gold electrode modified with nickelphthalocyanine and polypyrrole (NiPc/pPy/Au) in the presence of a cationic surfactant cetyltrimethyl ammonium bromide. Several techniques such as cyclic voltammetry, scanning electron microscopy, electrochemical impedance spectroscopy, energy dispersive X-ray spectroscopy and Raman spectroscopy have been employed for the characterization of modified electrodes. NiPc/pPy/Au modified electrode exhibited excellent electrochemical sensing and degradation ability towards SM. The present modification indicated two electron involvements in the electrocatalytic degradation of SM in addition to being an irreversible adsorption controlled process. Degraded products were identified by gas chromatography-mass spectrometry. Moreover, electrochemical parameters of oxidation of SM such as heterogeneous rate constant (0.436 s−1), transfer coefficient (0.47) and the number of electrons involved (2) were deduced from cyclic voltammetry results. The NiPc/pPy/Au modified electrode showed excellent electrocatalytic degradation towards SM when compared to bare gold, pPy/Au and NiPc/Au modified electrode at ambient conditions.

Oxidative degradation of chemical warfare agents in water by bleaching powder

Degradation of sulfur mustard (HD), S-2-(di-isopropylamino)ethyl O-ethyl methylphosphonothioate (VX) and Soman (GD) in water by bleaching powder was investigated. The degradation products were comprehensively analyzed by gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS) and ion chromatography. Degradation pathways were deduced based on the identified products. The product analysis results indicated that HD could be degraded through oxidation and chlorination reactions, and a small portion of sulfur atoms could be mineralized into SO(4)(2-) ion. Oxidative degradation of VX could finally generate O-ethyl methylphosphonate acid (EMPA), sulfonic acids, SO(4)(2-) and NO(3)(-) ions. GD would be converted into non-toxic pinacolyl methylphosphonate via nucleophilic substitution.

Mesoporous iron–manganese oxides for sulphur mustard and soman degradation

Substituted iron(III)–manganese(III, IV) oxides, ammonio-jarosite and birnessite, were prepared by a homogeneous hydrolysis of potassium permanganate and iron(III) sulphate with 2-chloroacetamide and urea, respectively. Synthesised oxides were characterised using Brunauer–Emmett–Teller (BET) surface area and Barrett–Joiner–Halenda porosity (BJH), X-ray diffraction (XRD), infrared spectroscopy (IR), Raman spectroscopy and scanning electron microscopy (SEM). The oxides were taken for an experimental evaluation of their reactivity against sulphur mustard (HD) and soman (GD). When ammonio-jarosite formation is suppressed by adding urea to the reaction mixture, the reaction products are mixtures of goethite, schwertmannite and ferrihydrite, and their degradation activity against soman considerably increases. The best activities for the degradation of sulphur mustard (97.9% in 64min) and soman (97.9% in 64min) were observed for FeMn_75 with 32.6wt.% Fe (36.8wt.% Mn) and FeMn_37U with 60.8wt.% Fe (10.1wt.% Mn) samples, respectively.