Hazardous or toxic waste destruction or containment – Containment – Solidification – vitrification – or cementation
Reexamination Certificate
2000-06-29
2003-05-20
Lovering, Richard D. (Department: 1712)
Hazardous or toxic waste destruction or containment
Containment
Solidification, vitrification, or cementation
C252S186410, C510S110000, C510S370000, C510S372000, C510S504000, C516S015000, C588S253000, C588S253000, C588S901000
Reexamination Certificate
active
06566574
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to materials for neutralization of chemical and biological compounds or agents, and especially chemical and biological weapons agents and their method of making. In particular, the present invention is directed to materials containing solubilizing compounds and reactive compounds that can be delivered as foams, sprays, liquids, fogs and aerosols to enhance the rate of reactions leading to neutralization of chemical compounds, and other additives which serve to kill or attenuate certain biological compounds or agents.
Terrorist threats, potentially involving weapons of mass destruction, are increasing both in the United States and abroad. The use, and threat of use, of chemical and biological agents in the context of weapons of mass destruction are of paramount concern both to national defense as well as to state and local law enforcement.
Certain CW agents known to pose a threat by terrorists share chemical characteristics that present an opportunity for the development of countermeasures. The chemical agents sarin, soman, and tabun (G-agents) are all examples of phosphorus-containing compounds which, when altered chemically, can lose their toxicity. Mustard, which is an example of the H-agents, and VX, which is an example of the V-agents, can also be altered chemically and rendered harmless. In addition, certain of the known BW agents include botulinum toxin, anthrax and other spore-forming bacteria, vegetative bacteria, including plague and various viruses can also be deactivated chemically.
A CW or BW attack can involve either local placement or wide dispersal of the agent or agents so as to affect a population of human individuals. Because of the flexibility with which CW and BW (CBW) agents can be deployed, respondents might encounter the agents in a variety of physical states including bulk, aerosol and vapors.
An effective, rapid, and safe (non-toxic and non-corrosive) decontamination technology is required for the restoration of civilian facilities in the event of a domestic terrorist attack. Ideally, this technology should be applicable to a variety of scenarios such as the decontamination of open, semi-enclosed, and enclosed facilities as well as sensitive equipment. Examples of types of facilities where the decontamination formulation may be utilized include a stadium (open), an underground subway station (semi-enclosed), and an airport terminal or office building (enclosed).
Decontamination of chemical compounds have focused primarily on chemical warfare agents, particularly on the nerve agents (such as G agents and V agents) and on the blistering agents (such as mustard gas, or simply, mustard). Reactions involved in detoxification of chemical agents can be divided into substitution and oxidation reactions. Decontamination of biological agents is primarily focused on bacterial spores (e.g., anthrax) which are considered to be the most difficult of all microorganisms to kill.
Substitution Reactions
Hydrolysis of chemical agents can be carried out with water, hydroxyl ions or other nucleophiles. The rate of hydrolysis of mustard and the nature of the products formed depends primarily on the solubility of the agent in water and on the pH of the solution. In the detoxification of mustard, for example, the molecule first forms a cyclic sulfonium cation, which reacts with nucleophilic reagents (Yang, 1995). The dominant product is thiodiglycol but this product may react with sulfonium ions to give secondary intermediates.
The hydrolysis of sarin (GB) and soman (GD) occurs rapidly under alkaline conditions and gives the corresponding O-alkyl methylphosphonic acid. In contrast, the hydrolysis of VX with OH
−
ions is more complex. In addition to displacement of the thioalkyl group (i.e., P—S bond breakage), the O-ethyl group is displaced (i.e., P—O bond breakage) producing a toxic product known as EA-2192 (Yang et al., 1997). Nucleophiles enter and depart the intermediate from an apical position. Electronegative groups, such as RO groups, preferentially occupy apical positions and groups that are bulky or electron donors, such as RS groups, occupy equatorial positions. The final product will depend on the balance between apicophilicity and leaving group ability. The result is that P—S bond cleavage is favored over P—O bond cleavage by a factor of about 5. Peroxyhydrolysis, on the other hand, using OOH
−
ions in alkaline medium was shown to involve quantitative P—S cleavage at rates 30-40 times that with OH
−
. This selectivity was related to the relative basicities of the anionic nucleophile and the leaving anions.
Catalytic species for acceleration of substitution reactions have been reported. One example is o-iodosobenzoate (IBA). An example illustrating the catalytic reactions of this compound is given by Moss and Zhang (1993). In this example, IBA is converted to iodoxybenzoate (IBX) via oxidation that then participates in the reaction with the CW agent.
The IBA compound was also functionalized to introduce surface activity (surfactant character) to the active group (Moss et al., 1986). Metal ion-amine complexes, with surface active moiety, were also developed and shown to exhibit catalytic effects in substitution reactions. Enzymes such as organophosphorous acid anhydrolase have also been shown to accelerate substitution reactions with the G and VX agents.
Oxidation Reaction
Oxidative decontamination methods are useful for mustard and VX (Yang, 1995). An early oxidant used was potassium permanganate. Recently, a mixture of KHSO
5
, KHSO
4
, and K
2
SO
4
was developed. Several peroxygen compounds have also been shown to oxidize chemical agents (e.g., perborate, peracetic acid, m-chloroperoxybenzoic acid, magnesium monoperoxyphthalate, and benzoyl peroxide). More recently, hydroperoxycarbonate anions produced by the reaction of bicarbonate ions with hydrogen peroxide have been shown to effectively oxidize mustard and VX. Polyoxymetalates are being developed as room temperature catalysts for oxidation of chemical agents but the reaction rates are reported to be slow at this stage of development. Some of these compounds undergo a color change upon interaction with chemical agents to indicate the presence of chemical agents.
The BW threat can be more serious than the CW threat. This is in part because of the high toxicity of BW agents, their ease of acquisition and production, and difficulty in detection. There are hundreds of biological warfare agents available for use by terrorists. They may be grouped into the categories of spore forming bacterium (e.g., anthrax), vegetative bacterium (e.g., plague, cholera), virus (e.g., smallpox, yellow fever), and bacterial toxins (e.g., botulism, ricin). Bacterial spores are recognized to be the most difficult microorganism to kill.
Bacterial spores are highly resistant structures formed by certain gram-positive bacteria usually in response to stresses in their environment. The most important spore-formers are members of the genera, Bacillus and Clostridium. Spores are considerably more complex than vegetative cells. The outer surface of a spore consists of the spore coat that is typically made up of a dense layer of insoluble proteins usually containing a large number of disulfide bonds. The cortex consists of peptidoglycan, a polymer primarily made up of highly crosslinked N-acetylglucosamine and N-acetylmuramic acid. The spore core contains normal (vegetative) cell structures such as ribosomes and a nucleoid.
Since their discovery, considerable research has been carried out to investigate methods to kill bacterial spores. Although spores are highly resistant to many common physical and chemical agents, a few antibacterial agents are also sporicidal. However, many powerful bactericides may only be inhibitory to spore germination or outgrowth (i.e., sporistatic) rather than sporicidal. Examples of sporicidal reagents, using relatively high concentrations, include glutaraldehyde, formaldehyde, iodine and chlorine oxyacids compounds, peroxy acids, and
Tadros Maher E.
Tucker Mark D.
Klavetter Elmer A.
Lovering Richard D.
Sandia Corporation
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