Solid composition, method and use for detoxifying a chemical warfare agent (CWA) and method of manufacture of solid composition

Abstract

The present invention relates to a solid composition for immobilising and detoxifying chemical warfare agents, methods of manufacture and methods of use of said composition.

Description

[0001] SOLID COMPOSITION, METHOD AND USE FOR DETOXIFYING A CHEMICAL WARFARE AGENT (CWA) AND METHOD OF MANUFACTURE OF SOLID COMPOSITION

[0002] Field of Invention

[0003] The present invention relates to a solid composition for immobilising and 5 detoxifying chemical warfare agents, for example sulfur mustard, lewisite, organophosphorus nerve agents and analogues thereof, methods of manufacture and methods of use of said composition.

[0004] Background to the Invention 0 Huge stockpiles of chemical warfare agent (CWA) filled munitions were manufactured in the first half of the 20th century, and many were subsequently dumped at sea, or buried underground.

[0005] One example of said CWAs is sulfur mustard, which is a persistent liquid5 CWA that was first used in World War 1. It has been used more recently in the Syrian conflict and remains a threat today. It is an incapacitating liquid chemical that causes severe skin blistering and respiratory irritation. Despite being a liquid, it is sometimes referred to as "mustard gas" due to its aroma, and it is banned under the Chemical Weapons Convention (CWC),0 where it is listed in schedule 1.

[0006] Sulfur mustard and other CWA-filled munitions are still periodically exposed by the tides below historic coastal test firing ranges and are ploughed up on historic battlefields. The CWAs found inside legacy munitions are typically5 still highly toxic, even though often the colour and consistency has changed considerably over the decades.

[0007] The clean-up, detoxification and decommissioning of chemical munitions and waste sites is a hugely costly and hazardous undertaking. The current0 primary method for the decontamination and disposal of these legacy munitions is high temperature thermal decomposition at purpose-built incineration facilities. However, the condition of CWA-containing munitions or storage containers, once uncovered after a long duration e.g., underground, is variable, and leakage into the local environment can render the packaging and transport of corroded munitions or storage vessels to an incineration facility challenging and undesirable.

[0008] There are other more traditional wet chemistry decontamination methods that can be used to neutralise CWAs. These methods are typically logistically intensive and produce large quantities of liquid waste. For example, sulfur mustard must first be dissolved into a large volume of organic solvent before neutralization and detoxification can take place (usually at high pH). The solvents used are often flammable, presenting storage, handling and transport challenges. A detoxifying agent such as a strong oxidant, or, more commonly, a highly caustic alkaline reagent, or mix of reagents is then added to the mix to detoxify the mustard through hydrolysis or other breakdown pathways. These reagents can also present transport, handling and storage challenges. Depending on the solvent used, this process involves dissolution and dilution of the CWA into volumes of solvent containing detoxification reactants that is significantly larger than the volume of the CWA itself (typically over ten times the volume), hence the decontamination cannot be carried out inside the CWA munition or storage vessel. Instead, the CWA must first be removed into a suitably sized detoxification vessel. The process creates a volume of contaminated solvent waste that is typically over ten times greater than the original volume of liquid CWA. This must be safely disposed of as toxic waste. The process can also be exothermic and release toxic and / or corrosive gases.

[0009] Accordingly, an improved way to detoxify CWAs which is cheaper and less hazardous is required.

[0010] Summary of the Invention According to a first aspect there is provided a composition for detoxifying a chemical warfare agent (CWA), wherein the composition is a solid, and wherein the composition comprises a halide salt, a nucleophile and an absorbent.

[0011] In a second aspect of the invention there is provided a method of manufacturing a composition for detoxifying a CWA, the method comprising the steps of:

[0012] (1) providing a solid halide salt, a solid or preabsorbed liquid nucleophile and a solid absorbent; (2) milling or grinding the halide salt, the nucleophile, the absorbent to form powders; (3) optionally drying the powders of step (2); (4) mixing the halide salt, the nucleophile and the absorbent powders together, before or after the optional drying in step (3); and (5) optionally pelletising the powder mixture.

[0013] In a third aspect of the invention there is provided a method of detoxifying a CWA, the method comprising the steps of: (1) providing a solid composition comprising a halide salt, a nucleophile and an absorbent; and (2) contacting the composition with the CWA, so that the CWA is absorbed into the absorbent and reacts with the halide salt and the nucleophile to become less toxic.

[0014] In a fourth aspect of the invention there is provided a use of a solid composition comprising a halide salt, a nucleophile and an absorbent to detoxify a CWA.

[0015] The invention provides a composition for and methods of detoxifying CWAs which advantageously enables detoxification of neat / undiluted CWAs. An important consequence of the detoxification of CWAs according to the invention, is that the chemicals are no longer useful as warfare agents. This is important in situations where the detoxified chemical agent cannot be removed from the site where the treatment takes place, for example, in a hostile environment.

[0016] In contrast to prior art methods, the need for diluting solvents and / or the addition of water is eliminated, as the composition is a solid, which has the advantage of making the composition easier to transport and store compared to liquid detoxifying agents. The composition is also safer to handle and use compared to liquid detoxifying agents and does not require excessive personal protective equipment (PPE).

[0017] Furthermore, the composition and methods advantageously allow for in-situ immobilization by absorbing the CWA, which are usually in liquid form, in an absorbent to form a solid matrix or solid material which, like the composition, is as easy to transport and store relative to existing detoxification agents. As such, this is preferable to traditional detoxification methods and prevents any further use, or recovery of, the liquid CWA.

[0018] Finally, the invention advantageously utilises readily available (commodity) materials, to provide a composition that offers a cost-effective alternative to existing methodologies.

[0019] Description

[0020] As used herein. The term "chemical warfare agent (CWA)" refers to toxic synthetic chemicals that have lethal or incapacitating effects on humans. The CWA is preferably in the form of a liquid. Examples of CWAs include, but are not limited to sulfur mustard, lewisite, chloropicrin, organophosphorus compounds such as venomous agent X (VX), sarin, tabun, paraoxon, malathion and analogues thereof. Preferably, the CWA is sulfur mustard or an analogue thereof. As used herein, the terms "sulfur mustard" or "mustard" refer to the compound bis(2-chloroethyl) sulfide. An example of a sulfur mustard analogue is 2-chloroethyl ethyl sulfide, also known as "half mustard".

[0021] Other sulfur mustard analogues include l,2-bis(2-chloroethylsulfanyl) ethane or "sesquimustard", bis(2-(2-chloroethylsulfanyl) ethyl) ether or "0- mustard", 2-chloroethyl chloromethyl sulfide, bis(2-chloroethylsulfanyl) methane, l,3-bis(2-chloroethylsulfanyl) propane, l,4-bis(2- chloroethylsulfanyl) butane l,5-bis(2-chloroethylsulfanyl) pentane and bis((2-2-chloroethylsulfanyl) methyl) ether.

[0022] As used herein, the terms "detoxifying" or "detoxification" refer to a process of chemically transforming a substance to produce a chemically different substance that is less toxic than the starting substance. Accordingly, by "detoxify" we mean that the CWA is rendered less toxic, preferably substantially less toxic than the starting CWA or non-toxic, when contacted with the composition. Preferably, at least about 70% of the original CWA is chemically transformed to a substance that is less toxic that the original CWA, or non-toxic, more preferably at least about 85%, most preferably at least about 99% of the original CWA is chemically transformed to a substance less toxic that the original CWA, or non-toxic, after contact with the composition. The terms "detoxify" and "decontaminate" may be used interchangeably and the skilled person would understand that the terms have the same meaning in this context. The detoxified end product may also be biodegradable.

[0023] The composition of the invention comprises a halide salt, a nucleophile and an absorbent. The compositions may consist essentially of or consist of a halide salt, a nucleophile and an absorbent. Preferably, the composition of the invention may comprise, consist essentially of or consist of an iodide salt, an amine or a thiol and an absorbent. More preferably, the composition of the invention may comprise, consist essentially of or consist of an iodide salt, a thiol and an absorbent.

[0024] Examples of suitable halide salts include lithium iodide, magnesium iodide, sodium iodide, potassium iodide, silver iodide, iron iodide, elemental iodine, potassium bromide, sodium bromide or combinations thereof. More than one halide salt may be used. Preferably, the halide salt is an iodide salt, for example potassium iodide or sodium iodide, more preferably sodium iodide. The applicants have found that sodium iodide and potassium iodide provide a good balance between commercial availability, acceptable shelf-life, and stability as well as ease of storage, processing, and packaging.

[0025] The nucleophile may be an aliphatic or aromatic amine, or an aliphatic or aromatic thiol, or combinations thereof. Preferably, the nucleophile is an aliphatic amine or aliphatic thiol. Most preferably the nucleophile is an aliphatic thiol.

[0026] Combinations of more than one aliphatic amine, or aliphatic thiol and / or combinations of more than one aromatic amine or aromatic thiol may also be used. When the nucleophile is aromatic, it is preferably a primary aromatic amine, or primary aromatic thiol. This is because compared to secondary or tertiary aromatic amines or thiols, the steric impedance of primary amines or thiols is generally lower. This means that the primary aromatic amines or thiols are generally comparatively smaller with a lower molecular weight. As explained in more detail below, it is desirable in part for logistical reasons, to keep the molar and / or mass ratio of CWA to the composition low. Hence, using a less bulky primary aromatic amine or thiol with a lower molecular weight is preferable. Suitable examples of aromatic primary amines include aniline, 1,3,5-benzenetriamine, or 4-aminopyridine.

[0027] Preferably the nucleophile is a primary aliphatic amine, diamine or thiol. This may be selected from ethylenediamine, cysteamine, 1,4 diazobicyclo [2,2,2] octane or combinations thereof. More preferably, the nucleophile is cysteamine.

[0028] The nucleophile may be provided as a solid (for example cysteamine) or as a pre-absorbed liquid (for example ethylenediamine or aniline). As used herein the term "pre-absorbed liquid" refers to a liquid amine that has been mixed with and absorbed by another substance, for example the absorbent and / or the halide salt. In this embodiment, the liquid amine is usually absorbed by the absorbent.

[0029] Preferred combinations of nucleophile and halide salt include cysteamine and sodium iodide or cysteamine and potassium iodide. An alternative preferred combination is ethylenediamine and sodium iodide or ethylenediamine and potassium iodide.

[0030] The absorbent may be a naturally occurring polysaccharide. For example, the absorbent may be cellulose based, preferably cellulose wood flour, a chemically modified derivative of wood flour, or may be chitin based, preferably chitosan, or a chemically modified derivative of chitosan.

[0031] The absorptive and reactive properties of the polysaccharide may advantageously be varied by chemically modifying the surface functionality for example by installing an amine and / or thiol group. Thus, a reactive nucleophilic component is incorporated into the absorbent, which may improve absorption and binding of the CWA. The hydrophilicity might also be altered to improve absorption by, for example, capping the terminal hydroxyl groups through acetylation. Improved absorption properties may improve the efficiency of the detoxification process for example by facilitating more even permeation of the CWA throughout the composition of the invention. Alternatively, the absorbent may be a synthetic polymeric material. The synthetic polymeric material is not particularly limited. Suitable examples include polymers with a nucleophilic functionality for example primary amines and / or thiols, which provide enhanced absorptivity towards sulfur mustard and analogues thereof. Alternatively, the polymer can be any synthetic polymer that provides an open structure for absorption or adsorption. Synthetic polymeric materials that can absorb or adsorb sulfur mustard or analogues thereof due to their structure may be suitable, for example polystyrene, an open cell polyolefin foam, a polymeric high internal phase emulsion, or a microporous hollow fibre.

[0032] The polymeric material may be in the form of a powder, for example a polymeric high internal phase emulsion, that either enhances absorption, or contains chemical functionality that renders the absorption and / or detoxification process more efficient, or both. A synthetic polymer with built in nucleophilic functionality e.g. primary amines and / or thiols, or enhanced absorptivity towards the CWA, could be used in place of a naturally derived polysaccharide to enhance detoxification of mustard and analogues when incorporated into the composition.

[0033] A combination of one or more different absorbents may be used. A combination of absorbents may be particularly advantageous if the CWA was found to be a non-homogeneous mixture of components with varying absorptivity.

[0034] The composition may contain at least about 12% absorbent by weight based on the total weight of the composition, usually in the range 5 to 50%, preferably 10 to 40% or 10 to 30% by weight, with all or the majority of the rest of the composition comprising halide salt and nucleophile, preferably in a defined molar ratio with each other as set out below. The proportion of absorbent is dependent on which halide salt and nucleophile are used in the composition. Accordingly, the amount of absorbent can be adjusted such that the total weight percentage of all components in the composition is equal to 100%.

[0035] Usually the composition comprises: 5 to 50%, preferably 10 to 40% or 10 to 30% by weight absorbent; 50 to 95%, preferably 60 to 90% or 70 to 85% by weight halide salt and nucleophile together, preferably in the preferred molar ratio; and optionally 0 to 20%, preferably 1 to 10% or 1 to 5% by weight additives.

[0036] The molar ratio of the halide salt to the nucleophile depends on the number of reactive nucleophilic sites on the nucleophile and the skilled person would easily be able to calculate the correct ratio. Examples of reactive nucleophilic sites are amine groups or thiol groups. For example, aniline contains one reactive nucleophilic site (a primary amine group), whereas cysteamine contains two reactive nucleophilic sites (a primary amine and a thiol group).

[0037] The halide salt and a nucleophile with one reactive nucleophilic site may be present in the composition in equimolar amounts, wherein the molar ratio is about 1 : 1. The molar ratio of halide salt to nucleophile with one reactive nucleophilic site may be about 0.5: 1 to about 1 :0.5, preferably about 0.8: 1 to about 1 :0.8 more preferably about 0.9: 1 to about 1 :0.9.

[0038] Where the nucleophile has two reactive nucleophilic sites, the molar ratio of halide salt to nucleophile present in the composition may be about 1 :0.5, and is preferably in the range about 1 : 1 to about 2:0.5, preferably about 1.6: 1 to about 2:0.8 more preferably about 1.8: 1 to about 2:0.9.

[0039] The molar ratio corresponds to the number of reactive nucleophilic sites on the nucleophile molecule and thus can be calculated as 1 mole halide salt to 1 / number of nucleophilic sites moles of nucleophile. For example, where the halide salt is an iodide salt and the nucleophile is an amine, the iodide salt and an amine with one reactive nucleophilic site may be present in the composition in equimolar amounts, wherein the molar ratio is about 1:1. The molar ratio of iodide salt to amine with one reactive nucleophilic site may be about 0.5:1 to about 1:0.5, preferably about 0.8:1 to about 1:0.8 more preferably about 0.9:1 to about 1:0.9.

[0040] Where the amine has two reactive nucleophilic sites, the molar ratio of iodide salt to amine present in the composition may be about 1:0.5, and is preferably in the range about 1:1 to about 2:0.5, preferably about 1.6:1 to about 2:0.8 more preferably about 1.8:1 to about 2:0.9.

[0041] Alternatively, the halide salt may be present in the composition in catalytic, sub-stoichiometric amounts. For example the ratio of halide salt to reactive nucleophilic site may be about 0.01:1, or about 0.02:1, or about 0.03:1, or about 0.04:1, or about 0.05:1, or about 0.06:1, or about 0.07:1, or about 0.08:1, or about 0.09:1, or about 0.1:1, or about 0.11:1, or about 0.12:1, or about 0.13:1, or about 0.14:1, or about 0.15:1. Preferably, the ratio is between about 0.05:1 and about 0.1:1.

[0042] When the halide salt is present in catalytic, sub-stoichiometric amounts, the molar ratio of nucleophile with one reactive nucleophilic site to CWA may be about 1:1 to about 3:1, preferably about 1.5:1 to about 2.5:1 more preferably about 1.8:1. to about 2.2:1.

[0043] When the halide salt is present in in catalytic, sub-stoichiometric amounts, and where the nucleophile has two reactive nucleophilic sites, the molar ratio of nucleophile to CWA may be about 1.5:1, and is preferably in the range about 2:1 to about 1:1, preferably about 1.2:1 to about 1.8:1 more preferably about 1.4:1 to about 1.6:1. Where the halide salt is present in catalytic, sub-stoichiometric amounts, the molar ratio of the halide salt to the nucleophile with one reactive nucleophilic site to CWA is preferably between about 0.2:3: 1 and about 0.5:3: 1, preferably about 0.25:3: 1.

[0044] The composition described herein is a solid, which has the advantage of making the composition easier to transport and store compared to liquid detoxifying agents. The composition is also safer to handle and use, compared to liquid detoxifying agents, and does not require excessive personal protective equipment (PPE), in contrast to prior art methods that do typically require higher levels of PPE.

[0045] The solid composition may be provided in the form of a powder, preferably a finely ground or granular powder. The particle size of the powder is not particularly limited. It is highly advantageous for all components of the composition to have a similar particle size to limit any separation.

[0046] Alternatively, the composition may be provided in the form of pellets. The size of the pellets may be about 2 mm to about 20 mm, preferably about 3 mm to about 15 mm, more preferably about 5 mm to about 10 mm. Pelletising the composition provides the advantages of reducing the hazards associated with handling powders, for example respiratory hazards, as well as minimising airborne contamination. Further the bulk volume is minimised in pellet form over powder form. The reaction between the CWA and the composition of the invention is also slowed down when the composition is in the form of a pellet, which is advantageous in the case of more reactive CWAs such as lewisite.

[0047] Figure 1 shows powdered and pelletised formulations of the composition described herein. The mass of the composition is the same in each vial, thus illustrating how much volume is saved by pelletising the composition. The composition may further comprise one or more additives which may prolong the shelf life of the composition, for example by substantially reducing or preventing the oxidation of the halide salt and / or nucleophile and removing any residual moisture. Suitable examples include one or more mineral sulfate, for example magnesium sulfate and / or silica and / or calcium silicate and / or ascorbic acid and / or tartaric acid. As above, one or more additives may typically be present in the composition in the amount of 0 to 20%, preferably 1 to 10% or 1 to 5% by weight based on the total weight of the composition.

[0048] Also provided herein is a method of manufacturing a composition for detoxifying CWAs, the method comprising the steps of: (1) providing a solid halide salt, a solid or preabsorbed liquid nucleophile and a solid absorbent; (2) milling or grinding the halide salt, the nucleophile and the absorbent to form powders; (3) optionally drying the powders of step (2); (4) mixing the halide salt, the nucleophile and the absorbent powders together, before or after the optional drying in step (3); and (5) optionally pelletising the powder mixture.

[0049] In step (3) of the method, the powders can be dried to a moisture content of less than about 7%, preferably less than about 5%, more preferably less than about 2%. The skilled person would be able to select a suitable standard analytical method for measuring moisture content, for example thermal gravimetric analysis (TGA). If the powders are already sufficiently dry, this step can be omitted.

[0050] The method may further comprise the step of packaging the composition by vacuum wrapping in a UV inert packaging or sealing in a container under an inert atmosphere.

[0051] As used herein, the term "UV inert packaging" means packaging that blocks or substantially blocks ultraviolet (UV) rays passing through it. As used herein the term "inert atmosphere" means an atmosphere of chemically unreactive gases in the given conditions. Examples of inert atmospheres include a nitrogen atmosphere or an argon atmosphere.

[0052] The type of packaging or container is not particularly limited. Examples of suitable packaging or containers include sacks, drums, and packets. These may be either commercially available or bespoke. The shape and flexibility of the packaging may be designed to allow the formulation to, for example, be introduced into containers with restricted openings, such as drums. Preferably, the composition is supplied under an inert atmosphere. Alternatively, the composition may be supplied under vacuum. The skilled person would readily be able to select which combination of formulation type and packaging type would suit the desired application.

[0053] Also provided herein is a method of detoxifying CWAs, the method comprising the steps of: (1) providing a solid composition comprising a halide, a nucleophile and an absorbent; (2) contacting the composition with the CWA, so that the CWA is absorbed into the absorbent and reacts with the halide salt and nucleophile to become less toxic.

[0054] The composition of the method provided may have any of the features of the composition described herein.

[0055] The CWA may be neat or undiluted which, as above, is highly advantageous over prior art chemical detoxification methods. As used herein, the terms "neat" or "undiluted" mean not diluted or mixed with another substance prior to detoxification.

[0056] Alternatively, the CWA maybe diluted, for example with an antifreeze agent or another agent which imparts beneficial properties, or may be in the form of an azeotrope. Where the CWA is in a solid form, preferably the CWA is dissolved in a minimum quantity of solvent prior to addition of the composition. A preferred solvent is dry acetone, however the skilled person will be able to select a suitable solvent depending on the CWA being detoxified.

[0057] Without being bound by theory, it is believed that when the composition contacts the CWA, the CWA is absorbed by the absorbent and is then chemically transformed. The exemplary reaction scheme below shows the chemical transformation of sulfur mustard to a less toxic compound. In this example, the nucleophile is an amine and the halide salt is an iodide salt.

[0058] As shown in the reaction scheme, sulfur mustard (structure 01) reversibly forms a transient cyclic sulfonium cation (structure Ola) which irreversibly reacts with an iodide salt to form a bis(2-iodoethyl) sulfide intermediate (structure 02). The bis(2-iodoethyl) sulfide intermediate irreversibly reacts with an amine to form the end product, which may be polymeric (structure 03). Without being bound by theory it is believed that the bis(2-iodoethyl) sulfide intermediate may also be in equilibrium with the corresponding sulfonium ion prior to nucleophilic attack by the amine.

[0059] The absorption of the CWA by the absorbent is usually comparatively faster than the chemical transformation steps. The solid composition of the invention enables the conversion of a highly toxic CWA liquid to a solid end product that is less toxic than the starting material, or non-toxic. The solid end product may also be biodegradable. Whilst it may be desirable to destroy the solid end product, for example by incineration, the quantity and handling of the solid end product is much improved compared with other wet detoxification methods, which often result in large volumes of caustic liquid waste.

[0060] As discussed above, the molar ratio of halide salt to nucleophile is dependent on the type and quantity of CWA and the number of reactive nucleophilic sites that are present per molecule of nucleophile. Accordingly, for example, when the halide salt is present in catalytic, sub-stoichiometric amounts, and where the nucleophile has one reactive nucleophilic site, the halide salt and nucleophile may be equimolar with or in a molar excess compared to the CWA, to ensure that all the CWA is detoxified. Preferably the molar ratio of the halide salt to the nucleophile with one reactive nucleophilic site to the CWA is between about 0.2:3: 1 and about 0.5:3: 1, preferably about 0.25:3: 1.

[0061] When the halide salt is present in catalytic, sub-stoichiometric amounts, and where the nucleophile has two reactive nucleophilic sites, for example cysteamine, the molar ratio of the halide salt to the nucleophile to the CWA is between about 0.2:0.75: 1 and about 0.4:2: 1, preferably about 0.25: 1.5: 1. The skilled person would readily be able to adjust the molar ratio based on the nucleophile used.

[0062] The mass ratio of the composition to the CWA thereof may be between about 5: 1 and about 2: 1, preferably about 4: 1 to about 2: 1, more preferably about 2: 1. The skilled person would be able to select a suitable mass ratio for the desired application. When the mass ratio of the composition to the CWA is below about 3: 1, preferably about 2: 1, a minimal quantity of the solid end product is produced. This makes the handling and disposal of the end product easier in comparison to wet detoxification methods which result in large volumes of liquid waste. This can be balanced with ensuring that all the CWA is reacted.

[0063] Detoxification using the composition of the invention can be performed across a broad range of temperatures, including ambient temperatures, for example about -5 °C to about 50 °C, or about 5 °C to about 48 °C , or about 14 °C to about 45 °C, or about 15 °C to about 40 °C, or about 15 °C to about 35 °C. Preferably, the reaction is conducted at about 20 °C to about 25 °C. This temperature range provides a balance between costs, stability and rate of reaction. As shown in figure 3, increasing the temperature generally increases the overall rate of the detoxification reaction. Performing the detoxification at temperatures in these ranges is advantageous over thermal incineration processes which require high energy input to produce high temperatures, typically of about 800 °C to about 1200 °C.

[0064] Sometimes, the CWA may be solid or frozen due to low temperatures where it is found. The skilled person may be able to safely melt the CWA by increasing the temperature or prevent freezing by adding an anti-freeze agent when the CWA is in liquid form.

[0065] For example, the melting point of neat sulfur mustard is about 14 °C. Therefore, to perform the detoxification process using the composition of the invention at temperatures of about 14 °C or below, the sulfur mustard would first need to be melted, for example by warming.

[0066] The composition may be provided as part of a reactive packaging or reactive packaging layer, which may aid the transport of frozen CWA. In this situation, if the CWA starts to thaw, it will be absorbed by the absorbent in the composition and detoxified. For example, a sulfur mustard munition may be placed in a drum containing the composition of the invention. Further composition of the invention may be added to the drum to encase or completely surround the munition for transport.

[0067] The process described herein does not require the use of solvents or liquid additives to dilute the CWA or to solubilise the detoxifying composition. The absence of such diluting / solubilising solvents means that the rate of reaction is comparatively slow because the liquid CWA is mixed with solid reagents and therefore the risk of exotherms or any gases being released is minimised. This is advantageous over traditional wet chemical detoxification processes where dilution is required using chemical solvents and the detoxification is typically carried out at high pH with a greater potential for exotherms and off-gassing.

[0068] Furthermore, the weight to weight (and volume to volume) ratio of the composition of the invention compared to other chemical detoxification methods is very favourable as there is no need for dilution or dissolution of the CWA into a chemical solvent mixture.

[0069] Also provided herein is the use of a solid composition comprising a halide salt, a nucleophile and an absorbent to detoxify a CWA. The use may comprise any of the features of the method of detoxifying CWAs described herein.

[0070] Advantageously the composition may be directly applied to neat CWA. For example, the composition may be scattered on a spill or leak of the CWA. Alternatively, the composition may provide detoxification of bulk quantities of the CWA when added to a munition or container of C\N / . The composition may also be used as a packing medium for leaking or corroded munitions during transportation. The composition may be added directly to a vessel containing CWA, preferably in excess, or the CWA may be pumped into a separate vessel containing the composition. The composition may be used in the form of a powder or a pellet for any of the above applications and the skilled person would be able to select the appropriate formulation for the desired use.

[0071] The ability to detoxify CWAs without transferring into a different vessel is advantageous over traditional wet chemistry detoxification methods. This is because these methods typically require the CWA to be transferred into a suitably sized detoxification vessel due to the use of large volumes of solvents and / or other chemicals.

[0072] Brief Description of the Drawings

[0073] The invention will now be described in detail, by way of example only, with reference to the figures.

[0074] Figure 1 shows a photograph containing an example of both the powder and pelletised formulation of the composition described herein.

[0075] Figure 2 shows a stack of Proton Nuclear Magnetic Resonance (XH NMR) spectra showing the transformation of the sulfur mustard analogue CEES over 48 hours.

[0076] Figure 3 shows a graph demonstrating an example of the breakdown of the sulfur mustard analogue CEES over time at various controlled temperatures.

[0077] Examples

[0078] Example 1

[0079] For decontaminating 1kg of sulfur mustard (6.29 moles), lithium iodide (6.91 moles, 926 grams), cysteamine (6.91 moles, 533 grams), and wood flour (541 grams) are combined under an argon atmosphere. The mixture is then ground in a ball mill under slight vacuum to help retain dryness, prior to packaging, or pelletising and packaging.

[0080] Example 2

[0081] For decontaminating 1kg of sulfur mustard (6.29 moles), sodium iodide (1.73 moles, 258.94 grams), cysteamine (15.73 moles, 1213.18 grams), wood flour (450 grams), calcium silicate (38.94 grams) and tartaric acid (38.94 grams) are combined under an argon atmosphere. The mixture is then ground in a ball mill under vacuum to help retain dryness, prior to packaging, or pelletising and packaging.

[0082] Example 3

[0083] 2-chloroethyl ethyl sulfide (also known as half mustard, or 'CEES'), is a universally accepted simulant for sulfur mustard and is commonly used in place of sulfur mustard as a lower toxicity surrogate for laboratory detoxification studies and trials.

[0084] To detoxify 2.0 mL of CEES (2.14 grams, 0.017 moles), 0.5 grams of wood flour; 0.64 grams of sodium iodide; 2.65 grams of cysteamine; 0.1 g tartaric acid and 0.1g of magnesium sulfate are combined under an argon atmosphere to provide a mixture with a total mass of 3.99g. The mixture is then ground in a ball mill under slight vacuum to help retain dryness, prior to packaging, or pelletising and packaging.

[0085] The preferred weight ratio of sulfur mustard or analogue to composition is 1 :2. Therefore the ratio of 2.14 g CEES :4.28g composition is the minimal recommended ratio to allow a 1.1 or greater molar excess of nucleophile. Sulfur mustard has a greater density than CEES so the molar excess would be greater if the same quantity (4.28g) of formulation was used. This is because 1 mole of CEES weighs 1.07g whereas 1 mole of sulfur mustard weighs 1.26g. Therefore, for a given weight of sulfur mustard there are fewer moles and thus less composition is needed, or if a 1 :2 ratio is used as recommended, there is a greater molar excess of the composition components, which is beneficial due to the two electrophilic ends to the molecule compared to one for CEES.

[0086] Example 4

[0087] The detoxifying composition was prepared as set out in Example 2. The detoxifying composition was added to CEES and samples were removed from the reaction at three different timepoints (5 hours, 24 hours, and 48 hours). The samples were extracted into NMR solvent (deuterated chloroform or deuterated acetonitrile) and submitted for analysis by proton NMR. and / or GCMS. NMR experiments were conducted using a 400MHz Bruker spectrometer. NMR data was processed using Bruker's Topspin software. GCMS experiments were conducted using Agilent instruments and software.

[0088] This procedure was repeated for Lewisite, Sarin, Tabun, Paraoxon and Malathion.

[0089] The proton NMR spectra produced from the reaction of the detoxifying composition with CEES are shown as a stack in figure 2.

[0090] The 5 hour spectrum shows largely residual CEES with the four labelled peaks (a, b, c, and d) identified showing the characteristic splitting patterns of each of the proton environments at their associated chemical shift. The baseline shows the beginnings of some breakdown peaks appearing associated with the halide intermediate.

[0091] The 24 hour spectrum shows the growth of product peaks (especially between 2.5-3.3ppm) and the relative diminishing of the CEES peaks which are still clearly present. The peaks at 2.93ppm and 3.24ppm are characteristic of the iodide intermediate (labelled e, f, g, and h). The 48 hour spectrum shows not just complete disappearance of CEES peaks, but also the disappearance of the iodide intermediate suggesting nucleophilic attack by the amine has led to an end product that could be polymeric in nature (labelled j, k, m, n, and o).

[0092] The GCMS results for the reactions between each of the CWAs and pesticides tested and the detoxifying composition are shown in Table 1 below.

[0093] Chemical warfare agent (CWA) or Pesticide analogue Detoxification

[0094] The GCMS results confirm detoxification of real neat CWAs and pesticide analogues with the composition described herein. Each detoxification experiment was performed as outlined in example 3 and was repeated on average 3 times. Table 1 shows that at least 99% of each CWA or pesticide analogue was chemically transformed to less toxic substances.

[0095] Example 5

[0096] The detoxifying agent was prepared as set out in Example 3 and added to CEES at three different temperatures (5, 20 and 30 °C). The percentage of CEES that degraded was monitored by proton N MR. over time and the results were plotted in the graph shown in Figure 3.

[0097] The plot shows the levels of residual CEES at various timepoints as determined by measurement of NMR peak integrals of CEES relative to breakdown products. The solid line (30 °C) shows the fastest degradation, with complete breakdown within 24 hours. The dashed line (20 °C) shows complete breakdown within 48 hours. The dotted line (5 °C) shows the slowest detoxification, with over 7 days required for complete breakdown of CEES.

[0098] This experiment shows that the detoxification is temperature dependant, and the rate of reaction increases when temperature is increased.

Claims

Claims1. A composition for detoxifying a chemical warfare agent (CWA), wherein the composition is a solid, and wherein the composition comprises a halide salt, a nucleophile, and an absorbent.

2. The composition according to claim 1, wherein the CWA is selected from sulfur mustard, lewisite, chloropicrin, sarin, tabun, paraoxon, malathion, venomous agent X (VX) and analogues thereof, preferably the CWA is sulfur mustard or an analogue thereof.

3. The composition according to claim 1, wherein the molar ratio of halide salt to nucleophile with one reactive nucleophilic site is about 0.15: 1 or the molar ratio of halide salt to nucleophile with two reactive nucleophilic sites is also about 0.15: 1.

4. The composition according to any preceding claim, wherein the halide salt is selected from lithium iodide, magnesium iodide, sodium iodide, potassium iodide, silver iodide, iron iodide, elemental iodine, sodium bromide, potassium bromide or combinations thereof.

5. The composition according to claim 4, wherein the halide salt is an iodide salt selected from lithium iodide, magnesium iodide, sodium iodide, potassium iodide, silver iodide, iron iodide, or combinations thereof, preferably wherein the halide salt is sodium iodide or potassium iodide.

6. The composition according to any preceding claim, wherein the nucleophile is a primary aliphatic amine or primary aliphatic thiol, preferably wherein the nucleophile is selected from ethylenediamine or cysteamine.

7. The composition according to any preceding claim, wherein the absorbent is a polysaccharide.

8. The composition according to claim 7, wherein the polysaccharide is cellulose based, preferably cellulose wood flour, a chemically modified derivative of wood flour, or is chitin based, preferably chitosan, or a chemically modified derivative of chitosan, or is an oligosaccharide such as [3-cyclodextrin, or a chemically modified derivative of [3-cyclodextrin.

9. The composition according to any of claims 1-6, wherein the solid absorbent is a synthetic polymeric material.

10. The composition according to any preceding claim, further comprising magnesium sulfate and / or calcium silicate and / or ascorbic acid and / or tartaric acid.

11. The composition according to any preceding claim, wherein the composition is in the form of a powder or a pellet.

12. A method of manufacturing a composition for a chemical warfare agent (CWA), the method comprising the steps of:(1) providing a solid halide salt, a solid or preabsorbed liquid nucleophile and a solid absorbent;(2) milling or grinding the halide salt, the nucleophile and the absorbent to form powders;(3) optionally drying the powders of step (2);(4) mixing the halide salt, the nucleophile and the absorbent powder together, before or after the optional drying in step (3); and(5) optionally pelletising the powder mixture.

13. The method of claim 12, further comprising the step of packaging the composition by vacuum wrapping in a UV inert packaging or sealing in a container under an inert atmosphere.

14. A method of detoxifying a chemical warfare agent (CWA), the method comprising the steps of:(1) providing a solid composition comprising a halide salt, a nucleophile and an absorbent;(2) contacting the composition with a CWA, so that the CWA is absorbed into the absorbent and reacts with the halide salt and nucleophile to become less toxic.

15. The method according to claim 14, wherein the CWA is undiluted.

16. The method according to claim 14 or 15, wherein the halide salt and nucleophile are both equimolar with or in a molar excess compared to the CWA for a nucleophile with one nucleophilic reactive site, preferably wherein the molar ratio of the halide salt to the nucleophile with one reactive nucleophilic site to the CWA is between 1 : 1 : 1 and 1.5: 1.5: 1, preferably about 1.2: 1.2: 1, more preferably about 1.1 : 1.1 : 1, and wherein when the nucleophile has two reactive nucleophilic sites, the molar ratio of the halide salt to the nucleophile to the CWA is between 1 :0.5: 1 and 1.5:0.75: 1, preferably about 1.2:0.6: 1, more preferably about 1.1 :0.55: 1.

17. The method according to claim 14 or 15, wherein the mass ratio of the composition to the CWA is between 5: 1 and 2: 1, preferably 4: 1 to 2: 1, more preferably about 2: 1.

18. The method according to claim 14 or 15, wherein the halide salt is present in a catalytic amount compared to the CWA, preferably in a molar ratio of about 0.25: 1.

19. The method according to claim 18, wherein when the nucleophile has one reactive nucleophilic site, the molar ratio of the halide salt to the nucleophile with one reactive site to CWA is preferably between about 0.2:3: 1 and about 0.5:3: 1, preferably about 0.25:3: 1.

20. The method according to claim 18, wherein when the nucleophile has two reactive nucleophilic sites, the molar ratio of the halide salt to the nucleophile to the CWA is between 0.2: 1 : 1 and 0.4: 2.5: 1, preferably about 0.25:2: 1.

21. The method according to any of claims 12 to 20, wherein the composition comprises one or more of the features of claims 2 - 11.

22. The method according to any of claims 12 to 20, wherein the CWA is sulfur mustard or an analogue thereof, the nucleophile is a thiol and the halide salt is an iodide salt.

23. Use of a solid composition comprising a halide salt, a nucleophile and an absorbent to detoxify a chemical warfare agent (CWA).

24. The use according to claim 23, wherein the use comprises any of the features according to claims 14-20.

25. The use according to claim 23, wherein the composition comprises an iodide salt, an amine and an absorbent to detoxify sulfur mustard or analogue thereof.

Images