Zinc oxide nanocubes as a destructive nanoadsorbent for the neutralization chemistry of 2-chloroethyl phenyl sulfide: A sulfur mustard simulant

Ultraviolet Light-Assisted Decontamination of Chemical Warfare Agent Simulant 2-Chloroethyl Phenyl Sulfide on Metal-Loaded TiO2/Ti Surfaces

The application of ultraviolet (UV) light for the decontamination of chemical warfare agents (CWAs) has gained recognition as an effective method, especially for treating hard-to-reach areas where wet chemical methods are impractical. In this study, TiO2/Ti was employed as a model catalyst, which was contaminated with 2-chloroethyl phenyl sulfide (CEPS), and subjected to photocatalytic decontamination using both UVB and UVC light. Additionally, photocatalytic decontamination efficiency by introducing Au, Pt, and Cu onto the TiO2/Ti surface was explored. During the photodecomposition process under UVC light, at least eight distinct secondary byproducts were identified. It was observed that the introduction of overlayer metals did not significantly enhance the photodecomposition under UVC light instead overlaid Au exhibited substantially improved activity under UVB light. Whereas, photodecomposition process under UVB light, only five secondary products were detected, including novel compounds with sulfoxide and sulfone functional groups. This novel study offers valuable insights into the generation of secondary products and sheds light on the roles of overlayer metals and photon wavelength in the photodecontamination process of CWA.

An Evaluation of the Biocatalyst for the Synthesis and Application of Zinc Oxide Nanoparticles for Water Remediation—A Review

Global water scarcity is threatening the lives of humans, and it is exacerbated by the contamination of water, which occurs because of increased industrialization and soaring population density. The available conventional physical and chemical water treatment techniques are hazardous to living organisms and are not environmentally friendly, as toxic chemical elements are used during these processes. Nanotechnology has presented a possible way in which to solve these issues by using unique materials with desirable properties. Zinc oxide nanoparticles (ZnO NPs) can be used effectively and efficiently for water treatment, along with other nanotechnologies. Owing to rising concerns regarding the environmental unfriendliness and toxicity of nanomaterials, ZnO NPs have recently been synthesized through biologically available and replenishable sources using a green chemistry or green synthesis protocol. The green-synthesized ZnO NPs are less toxic, more eco-friendly, and more biocompatible than other chemically and physically synthesized materials. In this article, the biogenic synthesis and characterization techniques of ZnO NPs using plants, bacteria, fungi, algae, and biological derivatives are reviewed and discussed. The applications of the biologically prepared ZnO NPs, when used for water treatment, are outlined. Additionally, their mechanisms of action, such as the photocatalytic degradation of dyes, the production of reactive oxygen species (ROS), the generation of compounds such as hydrogen peroxide and superoxide, Zn2+ release to degrade microbes, as well as their adsorbent properties with regard to heavy metals and other contaminants in water bodies, are explained. Furthermore, challenges facing the green synthesis of these nanomaterials are outlined. Future research should focus on how nanomaterials should reach the commercialization stage, and suggestions as to how this ought to be achieved are presented.

Effective degradation of sulfur mustard simulant using novel sulfur-doped mesoporous zinc oxide under ambient conditions

Sulfur doped metal oxides were synthesized using a two-step precipitation method. When reacted against neat 2-CEES (2-chloroethyl-ethyl sulfide, a mustard gas simulant) under ambient conditions, sulfur doped mesoporous zinc oxide (MS-Zn) showed higher catalytic activity than the other metal oxides with 92.7% overall conversion in 24 h for a 2.5 μL neat 2-CEES droplet added on top of 2 × 2 cm large 400 mg catalyst layer. The reaction proceeded mainly by hydrolysis and further solvolysis reaction also occurred depending on the extracting solvents. Cyclic sulfonium ion intermediate reaction was thought to be involved in this reaction, and metal oxide surfaces were thought to facilitate the formation of sulfonium ions from adsorbed 2-CEES. All other by-products were also found to form via sulfonium ions, reconfirming the well-known importance of this intermediate species for the degradation reaction to proceed. The sulfur content for MS-Zn was varied and tested for degradation of neat 2-CEES. This modification showed that there is an optimal amount of sulfur content for the peak catalytic activity of MS-Zn for 2-CEES degradation. Adsorption energy of a 2-CEES molecule was calculated on model sulfur doped and non doped zinc oxide surfaces and the different adsorption energy levels were correlated with the catalytic activity of sulfur doped zinc oxide.

Decomposition of the Simulant 2-Chloroethyl Ethyl Sulfide Blister Agent under Ambient Conditions Using Metal-Organic Frameworks

Metal organic frameworks (MOFs) have been suggested as promising materials for application in the degradation of chemical warfare agents, with the majority of studies to date focusing on nerve agents. One of the most prominent MOFs used in the detoxification of nerve agents is UiO-66, which is of interest as a future nerve agent decontaminant. However, blister agents, which constitute one of the most toxic and highly reactive categories of chemical agents, are yet to be examined as gas-phase decontamination targets using MOF structures. In this study, a novel type of UiO-66 with a smaller particle size, namely, UiO-66S, was used as a decontaminant for the blister agent simulant, 2-chloroethyl ethyl sulfide (2-CEES). The gas-phase chemical adsorption and decomposition of 2-CEES were demonstrated for the first time, with an estimated t_1/2 of 1.34 h. This value is the highest reported value for an MOF in gas-phase reaction conditions. The obtained nontoxic degradation products were identified, and the reaction mechanism was studied using density functional theory calculations. Furthermore, the synthesized UiO-66S catalyst also exhibits superior catalytic ability toward nerve agent simulants (diisopropyl fluorophosphate).The results of the study provide a firm basis for the use of UiO-66S as a future decontaminant for both nerve and blister agents.

A NaX zeolite framework containing magnetic MgFe2O4/CdO nanoparticles: synthesis, characterization and catalytic performance in the decontamination of 2-chloroethyl phenyl sulfide (2-CEPS) as a model of sulfur mustard agent

Magnetic MgFe2O4/CdO nanoparticles were immobilized in a zeolite NaX network and their application for the decontamination of sulfur mustard agent simulant 2-CEPS was evaluated.

Synthesis and characterization of TiO2/Mg(OH)2 composites for catalytic degradation of CWA surrogates

Surface catalyzed reactions can be a convenient way to deactivate toxic chemical warfare agents (CWAs) and remove them from the contaminated environment. In this study, pure titanium oxide, magnesium hydroxide, and their composites TiO₂/Mg(OH₂) were prepared by thermal decomposition and precipitation of the titanium peroxo-complex and/or magnesium nitrate in an aqueous solution. The as-prepared composites were examined by XRD, XPS, HRTEM, and nitrogen physisorption. Their decontamination ability was tested on CWA surrogates and determined by high-performance liquid chromatography (HPLC) and gas chromatography coupled with mass spectrometry (GC-MS). Dimethyl methyl phosphonate (DMMP) was used as a G simulant for the nerve agents sarin (GB) and soman (GD) while 2-chloroethyl ethyl sulfide (2-CEES) and 2-chloroethyl phenyl sulfide (2-CEPS) were used as surrogates of sulfur mustard (HD). The activity of the as-prepared composites was correlated with acid–base properties determined by potentiometric titrations and pyridine adsorption studied by in situ DRIFTS. The mixing of Ti and Mg led to an increase of the surface area and the amount of surface –OH groups (with an increasing amount of Ti) that caused improved degradation of DMMP.

Surface catalyzed reactions can be a convenient way to deactivate toxic chemical warfare agents (CWAs) and remove them from the contaminated environment.