Cleaning and liquid contact with solids – Processes – Using solid work treating agents
Reexamination Certificate
2000-12-21
2003-03-25
Markoff, Alexander (Department: 1746)
Cleaning and liquid contact with solids
Processes
Using solid work treating agents
C134S006000, C134S042000, C588S253000
Reexamination Certificate
active
06537382
ABSTRACT:
U.S. GOVERNMENT INTEREST
The invention described herein may be manufactured, used and licensed by or for the United States Government.
FIELD OF THE INVENTION
This invention relates to reactive sorbents and methods of making and using the same for the decontamination of surfaces contaminated with highly toxic materials, including chemical warfare (“CW”) agents and/or industrial chemicals, insecticides, and the like. More particularly, the invention relates to improvement of surface decontamination processes and reagents by the development of novel sorbents and sorbent preparation methods, including compositions comprising sodium zeolite (NaY) and silver exchanged zeolite (AgY).
BACKGROUND OF THE INVENTION
Exposure to toxic agents, and especially CW agents, and.related toxins, is a potential hazard to the armed forces and to civilian populations, since CW agents are stockpiled by several nations, and other nations and groups actively seek to acquire these materials. Some commonly known CW agents are bis-(2-chloroethyl) sulfide (“HD” or mustard gas), pinacolyl methylphosphonofluoridate (“GD”), 0-ethyl S-(2-diisopropyamino)ethyl methylphosphonothiolate (“VX”), and isopropyl methylphosphonofluoridate, or Sarin (“GB”) as well as analogs and derivatives of these agents. Although originally introduced in WWI, mustard gas has been used in recent times, as have the newer and more deadly nerve agents VX and GB (Zurer, 1998
, Chem. and Eng. News
76: 7; Black, et al., 1994
J. Chromatogr. A
662: 301-321; Black, et al., 1993
J. Chromatogr. A
637: 71-80; Rouhi, 1999
Chem. and Eng. News
77: 37; Ember,
Chem. and Eng. News
76: 6-7).
These CW agents are generally delivered as fine aerosol mists which, aside from presenting an inhalation threat, will deposit on surfaces of military equipment and hardware, including uniforms, weapons, vehicles, vans and shelters. Once such equipment and hardware is contaminated with one of the previously mentioned highly toxic agents, the agent must be removed in order to minimize contact hazards.
For this reason, there is an acute need to develop and improve technology for decontamination of highly toxic materials. This is especially true for the class of toxic materials known as nerve agents or nerve gases that are produced and stockpiled for both industrial use and as CW agents. Simply by way of example, one class of nerve agents with a high level of potential lethality is the class that includes organophosphorus-based (“OP”) compounds, such as Sarin, Soman, and VX. Such agents can be absorbed through inhalation and/or through the skin of an animal or person. The organophosphorus-type (“OP”) CW materials typically manifest their lethal effects against animals and people by inhibiting acetylcholine esterase (“AChE”) enzyme at neuromuscular junctions between nerve endings and muscle tissue to produce an excessive buildup of the neurotransmitter acetylcholine, in an animal or person. This can result in paralysis and death in a short time.
CW agents and related toxins are so hazardous that simulants have been developed for purposes of screening decontamination and control methods. These simulants include, e.g. 2-chloroethylphenyl sulfide (CEPS), an HD simulant, dimethyl methylphosphonate (DMMP), a G-agent simulant, and O,S-diethyl phenylphosphonothioate (DEPPT) a VX simulant.
One approach to cleanup and decontamination of the highly toxic agents is to develop various types of sorbents to trap and hold the CW agents to facilitate their removal. For example, the U.S. Army uses a nerve agent decontamination solution, DS2, which is composed (by weight) of 2% NaOH, 28% ethylene glycol monomethyl ether, and 70% diethylenetriamine (Richardson, G. A. “Development of a package decontamination system,” EACR-1 310-17, U.S. Army Edgewood Arsenal Contract Report (1972), incorporated by reference herein). Although this decontamination solution is effective against OP nerve agents, it is quite toxic, combustible, highly corrosive, and releases toxic by-products into the environment.
Another decontamination material, used as an alternative to DS2, is XE555 sorbent (Ambergard™ Rohm & Haas Company, Philadelphia, Pa.). XE555 is presently being used by the military for immediate decontamination applications. However, XE555 has several disadvantages. Although effective at removing chemical agents, XE555 does not possesses sufficient reactive properties to neutralize the toxic agent(s) picked up by this sorbent. Thus, after use for decontamination purposes, XE555 itself presents an ongoing threat from off-gassing toxins and/or vapors mixed with the sorbent.
It would be desirable to have a sorbent that is reactive, which degrades or decontaminates the toxic agent after adsorbing or absorbing the agent. There are reports that such “reactive sorbents” are being developed for the decontamination of chemical warfare agents, including those by, Yang, Y. -C., et al. 1992
Chem. Rev
., 92;1729-1743; Yang, Y. -C., 1995
Chem. Ind
., 334-337; Ekerdt, et al., 1988
, J. Phys. Chem
. 92: 6182-6188; Wagner, et al., 1999
J. Phys. Chem. B
, 103; 3225-3228; Spafford, R. B.
The Development of a Reactive Sorbent for Immediate Decontamination, ERDEC
-
CR
-218, U.S. Army ERDEC: Aberdeen Proving Ground, Md., 1996.
However, to date, none of these reports has described a useful and effective reactive sorbent for the most toxic CW agents, such as VX, HD and GD.
Chemical reactions for neutralizing CW agents are known, although they have not proved useful for decontamination. For example, it has been shown that VX and HD decompose on sorbents impregnated with AgF (Ekerdt, et al, 1988
, J. Phys. Chem
. 1988, 92:6182-6188) and gaseous HD decomposes on 13X zeolite (Bellamy, 1994
, J. Chem. Soc. Perkin Trans
. 2:2325-2328). AgF is currently used to transform VX vapor into its more volatile G-analog, ethyl methylphosphonofluoridate, to facilitate its detection by air monitoring equipment (Spafford, 1996, “The Development of a Reactive Sorbent for Immediate Decontamination,” ERDEC-CR-218, U.S. Army ERDEC: Aberdeen Proving Ground, Md.). This reaction is not useful for decontamination purposes, because corrosive HF byproduct also forms, although the reaction mechanism is apparently not completely known (Spafford, 1996, Id.).
For HD vapor on 13X zeolite, Bellamy, 1994 (
J. Chem. Soc. Perkin Trans
. 2:2325-2328) tentatively assigned a product detected by
13
C MAS NMR to the sulfonium ion CH—TG. CH—TG is formed from the chlorohydrin (CH) and thiodiglycol (TG) hydrolysis products of HD (Yang, Y. -C. et al., 1988
, J. Org. Chem
. 53:3293-3297). The predominate formation of CH—TG from HD sorbed in soil by
13
C MAS NMR has similarly been reported (Wagner et al., 1998
, Langmuir
14:6930-6934). This pathway is illustrated by the following reaction scheme. (see Yang, et al., 1988, J.
J. Ore. Chem
. 53:3293-3297).
Although a number of metal ions are known to catalyze G-agent hydrolysis (Courtney, et al., 1957
Am. Chem. Soc
. 79:3030-3036; Epstein, et al., 1958
J. Am. Chem. Soc
. 80:3596-3598), with the possible exception of the AgF reaction, demonstrative examples of metal-catalyzed hydrolysis of VX appear to be lacking (Yang, Y. -C. 1999
, Acc. Chem. Res
. 32:109-115). Indeed, in perhaps the sole example, the hydrolysis of VX in buffered solutions of TMEN [N,N,N′,N′-tetrariethylethylenediamine] copper (II) complexes (Albizo, et al., 1987, In
Proceedings of the
1986
CRDEC Scientific Conference on Chemical Defense Research, Vol. I, CRDEC
-
SP
-87008, U.S. Army CRDEC: Aberdeen Proving Ground, Md., pp. 105-109), it is speculated that catalysis may be inhibited by competing complexation of the diisopropylamino group of VX (Yang, et al., 1992
, Chem. Rev
., 92:1729-1743).
Silver possesses a strong affinity for the complexation of sulfur-containing ligands (Cotton, et al., 1988, In
Advanced Inorganic Chemistry
, 5
th
ed., John Wiley & Sons, New York, pp. 942-943), and Ag
+
has been shown to promote the hydrolysis of diethyl ethylphosphonothioate (Saville, B. 1957 “Cation Assisted Nucleop
Bartram Philip W.
Wagner George W.
Biffoni Ulysses John
The United States of America as represented by the Secretary of
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