Hazardous or toxic waste destruction or containment – Containment – Solidification – vitrification – or cementation
Reexamination Certificate
2002-08-07
2004-04-20
Webb, Gregory (Department: 1751)
Hazardous or toxic waste destruction or containment
Containment
Solidification, vitrification, or cementation
C510S505000
Reexamination Certificate
active
06723891
ABSTRACT:
GOVERNMENT INTEREST
The invention described herein may be manufactured, used and licensed by or for the U.S. Government.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to decontamination of chemical warfare agents. More particularly, the invention relates to the decontamination of mustard agents such as HD by oxidation, as well as nerve agents such as VX and GD by perhydrolysis, using environmentally safe reactants.
2. Description of the Related Art
Several types of toxic chemical compounds are known to be useful as chemical warfare agents. These include mustard agents or gases known as blister agents, such as bis-(2-chloroethyl)sulfide, also known as HD, and nerve agents such as pinacolyl methylphosphonofluoridate, which is also known as GD, and O-ethyl S-(2-diisopropylamino)ethyl methylphosphonothioate, which is known as VX. HD is a colorless, oily liquid that is highly insoluble in water, and is a powerful vesicant which primarily affects the eyes and the lungs, blisters the skin and is considered a carcinogen. HD is also cytotoxic to hematopoietic tissue and can be lethal at high doses. GD and VX are powerful nerve agents that attack the nerve cells and impair the functioning of the central nervous system.
In order to decontaminate the vesicant mustard gas to render it non-toxic, it is necessary to oxidize it to the corresponding sulfoxide. Nerve agents such as VX and GD are rendered non-toxic by perhydrolysis to their non-toxic phosphonic acids. For example, the oxidation of HD to HD-sulfoxide (HDO) renders the gas non-toxic. One effective way to conduct this oxidation reaction is by reacting the agent with peroxide compounds. Mildly-basic peroxide is also known to effect the perhydrolysis of VX and GD to their non-toxic phosphonic acids. Peroxides are desirable reactants for decontamination because they are non-toxic and non-corrosive, as compared to hypochlorite-based processes which are toxic and environmentally harmful. Additionally, peroxides are preferable because of their extremely low freezing points. However, while it is desirable to decontaminate chemical warfare agents by oxidation in a peroxide system, presently known systems are inefficient decontaminates because they cause secondary oxidation of the corresponding sulfoxide to a sulfone, a toxic vesicant. For example, HD-sulfoxide is a non-vesicant, while HD-sulfone is a highly toxic vesicant material. Also, known peroxide systems using hydrogen carbonate ions as an activator are inefficient because the oxidation reaction is very slow. However, hydrogen carbonate activator is efficient at generating peroxy anion (OOH
31
) for VX and GD perhydrolysis.
Currently, efforts are being undertaken to speed up the oxidation reaction of HD to its sulfoxide, while avoiding the formation of HD sulfone. The rapid, simultaneous perhydrolysis of VX and GD is also desired. Applicants now have discovered a decontamination system that utilizes a peroxide/molybdate reactant system in a water-in-oil microemulsion. The molybdate in the system acts as a peroxide activator by either generating singlet oxygen (
1
O
2
) which diffuses out of the microemulsion and reacts with substrates in a bulk organic solvent, or via generation of peroxomolybdate species of the formula Mo(O)
x
(O—O)
4−x
2−
, wherein x=0-3. Applicants have further found that when the peroxomolybdate species is present particularly as a tetraperoxomolybdate Mo(OO)
4
2−
dominant species, the decomposition of the peroxide is avoided and
1
O
2
production is greatly diminished. It has also been found that a tetraperoxo dominant species causes a rapid oxidation of HD to HD-sulfoxide with a rate increase of at least one order of magnitude compared to hydrogen carbonate ion activated systems, while any secondary oxidation of HD-sulfoxide to HD-sulfone occurs at a rate of at least two orders of magnitude slower than a hydrogen carbonate ion activated system. The mild basicity of the molybdate activator further provides for the perhydrolysis of nerve agents VX and GD. The system functions in a variety of microemulsions, exhibits high stability and does not freeze at low temperatures.
SUMMARY OF THE INVENTION
The invention provides a process for decontaminating a chemical warfare agent comprising:
contacting at least one compound having a formula selected from the group consisting of
ROP(O)(CH
3
)F, wherein R is either 2-propyl, pinacolyl, or cyclohexyl;
R″OP(O)(CH
3
)SR′, wherein R″ is ethyl and R′ is 2-(diisopropylamino)ethyl; and bis(2-chloroethyl)sulfide, with a peroxomolybdate compound having the formula Mo(O)
x
(O—O)(
4−x
)
2−
, wherein x=0-3
The invention also provides a process for decontaminating a chemical warfare agent comprising:
a) forming a peroxomolybdate compound having the formula Mo(O)
x
(O—O)
(4−x)
2−
, wherein
x=0-3 by reacting a peroxide component and a molybdate component; and
b) contacting said peroxomolybdate compound with at last one chemical warfare agent having a formula selected from the group consisting of:
ROP(O)(CH
3
)F, wherein R is either 2-propyl, pinacolyl, or cyclohexyl;
R″OP(O)(CH
3
)SR′, wherein R″ is ethyl and R′ is 2-(diisopropylamino)ethyl; and bis(2-chloroethyl)sulfide.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention pertains to a process for decontaminating vesicant compounds and nerve agents used as chemical warfare agents. The chemical warfare agents are decontaminated by contacting the agent with a sufficient amount of a peroxomolybdate compound for a sufficient time and under conditions sufficient to produce a non-toxic reaction product. While the present invention is particularly useful for decontamination of mustard gases, it has a broad-spectrum of reactivity toward a variety of chemical warfare agents, even in cold weather operations, while achieving a significant reduction in the toxic, corrosive and environmentally harmful nature of other known decontaminants. The invention is particularly useful for decontaminating vesicant mustard gases. The invention is also useful for decontaminating G and V nerve agents having the following generic formulas: G: ROP(O)(CH
3
)F, wherein R is either 2-propyl (GB), pinacolyl (GD), or cyclohexyl (GF); V: R″OP(O)(CH
3
)SR′, wherein R″ is ethyl and R′ is 2-(diisopropylamino)ethyl (VX). More particularly, the chemical warfare agents decontaminated herein include mustard agent bis(2-chloroethyl)sulfide (HD), and nerve agents pinacolyl methylphosphonofluoridate (GD) and O-ethyl S-[2-(diisopropylamino)ethyl]methylphosphonothioate (VX).
The process includes forming a peroxomolybdate compound having the formula Mo (O)
x
(O—O)
(4−x)
2−
, wherein x=0-3, in a suitable medium by reacting a peroxide component and a molybdate component in the medium. The preferred medium is a microemulsion which is described below. The peroxide component comprises a material selected from the group consisting of hydrogen peroxide, solid urea hydrogen peroxide, sodium percarbonate peroxide and combinations and derivatives thereof. Of these, the preferred peroxide is a 50% aqueous H
2
O
2
. Solid urea hydrogen peroxide is also particularly applicable to address concerns of storage and handling of concentrated aqueous hydrogen peroxide in the field. Additionally, solid urea hydrogen peroxide is non-toxic and environmentally friendly. The peroxide component is preferably present in the microemulsion at from about 1 to about 25 weight percent, more preferably from about 5 to about 20 weight percent, and most preferably from about 8 to about 15 weight percent.
The molybdate component of the invention is comprised of an alkali metal molybdate. The alkali metal preferably comprises a metal selected from the group consisting of Li, Na, K, Rb, Cs, Fr. More preferably, the alkali metal comprises either lithium (Li), sodium (Na) or potassium (K). Most preferably the molybdate component comprises a molybdate potassium salt, p
Bunton Clifford A.
Procell Lawrence R.
Wagner George W.
Yang Yu-Chu
Biffoni Ulysses John
The United States of America as represented by the Secretary of
Webb Gregory
LandOfFree
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