Tuesday, October 6, 2009

Catalytic Nanoparticles Can Clean-Up Environment, Thwart Terrorists

By using catalytic and magnetic nanoparticles, two Massachusetts Institute of Technology (Cambridge, MA) researchers have discovered a better way to destroy deadly chemicals found in the environment and that terrorist could use in a attack.

The presence of organophosphate esters (OPE) in industrial and agricultural drain waters, spills, runoffs, and drifts, as well as OPE agent-based chemical munitions that may be released in case of warfare or terrorist attack, pose great risks to human health and the environment. The number of exposures to OPE due to pesticides and insecticides is estimated at some 3,000,000 per year, with the total number of deaths and casualties over 300,000 per year worldwide. U.S. Patent 7,598,199 reveals how these deadly chemicals can be safely and more easily detected and removed from the environment.

T. Alan Hatton and Lev E. Bromberg developed compositions and methods for sorbing and destroying organophosphate chemical agents. To this end, the researchers use finely divided, modified nanoscale metal oxide particles. A suspension of magnetite (Fe3O4) nanoparticles modified with 2-pralidoxime or its polymeric analog, poly(4-vinylpyridine-N-phenacyloxime-co-acrylic acid), catalyzes the hydrolysis of organophosphate compounds at a neutral pH. The oxime-modified magnetite particles serve as a nano-sized particulate carrier with a powerful .alpha.-nucleophile, e.g., an oximate group, immobilized on its surface. The oxime-modified magnetite nanoparticles are colloidally stable at neutral pH and they are readily recovered from the aqueous milieu by high-gradient magnetic separation methods. Advantage can be taken of the superparamagnetic properties of the magnetite particles to separate the catalyst from the reaction medium following use, allowing multiple uses.

The immobilized metal complexes have uses in addition to their use to decontaminate areas contaminated with nerve agents and/or pesticides. For example, the catalytic hydrolysis of nerve agents or pesticides using the nano-compositions can be employed as the operative process step in a detector system wherein the by-products of the hydrolysis reaction, such as hydrogen fluoride, may be subject to measurement to provide an indication of the presence and concentration of a particular phosphate ester in the environment. Additionally, the adsorbent nucleophilic particles may be fabricated in the form of filters, sponges, wipes, powder or any other form suitable for use in a decontamination process. For example, the particles may be used in gas masks, wearable protective garments, air filtration systems, and the like.

Numerous OPE pesticides, insecticides and warfare agents, such as sarin, soman, and VX, in addition to being carcinogenic, act as nerve poisons which may cause cumulative damage to the nervous system and liver. Organophosphorus pesticides and warfare agents are not readily hydrolyzed in aqueous media without applying extremes of pH, heat, or bleach. At present, the decontamination solutions of choice are DS-2 (a non-aqueous liquid composed of diethylenetriamine, ethylene glycol, monomethyl ether, and sodium hydroxide) and STB (super tropical bleach). Although DS-2 is generally not corrosive to metal surfaces, it damages skin, paints, plastics, rubber, and leather materials. STB, while effective, has the same environmental problems as bleaches and cannot be used on the skin. Consequently, personal decontamination equipment typically consists of packets of wipes containing such chemicals as sodium hydroxide, ethanol, and phenol. Hatton and Bromberg’s discovery presents a safer and easier alternative to DS-2.

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