Introducing MethBr Scrubbing Technology: Instantaneous Capture
and Destroy for Quarantine/Preshipment, Critical, and Emergency Use

Peter J. Joyce
President
Value Recovery, Inc.
510 Heron Drive, Suite 301
Bridgeport, NJ 08014
e-mail: joyce@ptcvalue.com

Methyl bromide's reactivity has not been thoroughly explored as a capture-and-destroy removal strategy to protect the ozone layer. This critical attribute—reactivity—is both methyl bromide's most beneficial attribute with respect to fumigation efficacy and its Achilles' heel with respect to environmental impact. When used as a fumigant, methyl bromide can interrupt an organism's internal chemical reactions, thus shutting down the organism. In the upper atmosphere, methyl bromide reacts at low temperatures with ozone, thus destroying the ozone layer's ability to provide protective filtering of UV light from the sun. Harnessing methyl bromide's reactivity in the form of a scrubbing solution that has been designed to provide exceptionally high reaction rates is the key to a new capture-and-destroy strategy that may supply the missing link in the methyl bromide phase-out program.

Value Recovery, Inc., of Bridgeport, New Jersey, believes that exploiting methyl bromide's strong suit, its reactivity, can result in an effective, safe, and cheap way to keep methyl bromide from ever reaching the upper atmosphere. The process takes place in a "reactive scrubber." Methyl bromide—laden air is forced through the reactive scrubbing solution and the air emerges essentially free of methyl bromide. A water-soluble organic compound or anion in the scrubbing liquor reacts with the methyl bromide to form a benign organic product and sodium bromide.

The technology used is based on phase transfer catalysis or PTC, whose salient feature is that it brings reactants from different phases together to react when they normally would not have a chance of reacting. PTC has been around for over 30 years and is the subject of over 2,000 patents and 10,000 peer-reviewed journal articles. Elite academics and specialty chemical companies use PTC to make high-molecular-weight pharmaceutical chemicals and other similar sophisticated molecules. PTC participates in at least one manufacturing step in over $10 billion worth of specialty chemical sales. Currently, Value Recovery is the only company dedicated to applying PTC to the environmental field. The company has identified over 180 million kg per year of production-related waste documented in the U.S. Toxic Release Inventory that could be transformed into salable products using PTC technology. Funding for this work was initiated under the U.S. Department of Energy Office of Industrial Technology.

A small-scale field demonstration of the technology was done on February 28, 2003, in conjunction with Rudi Scheffrahn of the University of Florida, who is advocating using methyl bromide to destroy anthrax spores. During fumigation of a University of Florida office trailer containing surrogate anthrax spores, a slipstream containing over 20,000 ppm (>80 oz/1000 ft³) of methyl bromide was charged to small gas washing bottles containing the reactive scrubber solution. The outlet concentration averaged 4 ppm and a steady-state value of 2 ppm was achieved in a 4-hour test demonstrating over 99.9 percent removal in less than 1 second of contact time. The air feed rate in the gas washing bottles was very low so these experiments do not represent a conclusive test in terms of commercial viability. However, the results do show that the reaction rate is exceptionally fast and that the reaction rate does not control the overall removal rate of methyl bromide from air. Thus, the approach is similar to scrubbing acid gases such as hydrochloric acid with sodium hydroxide to make sodium chloride (table salt) and water. This process also uses a reactive scrubber principle where the acid-base reaction is very fast. Results from the Florida test are available at http://www.ptcvalue.com/app3.asp.

The scrubber liquor used in the Florida tests is not suitable for introduction into the environment because the waste produced from it would be hazardous. Thus, this particular formula would be used only for demonstration. However, subsequent research results (as yet unpublished) from the company show that a formula based on a nonhazardous scrubbing liquor is feasible and that the company is actively working in this direction. The components of the scrubbing liquor are both cheap and relatively easy to acquire. The next steps are to scale the process up to conventional scrubber contacting equipment and to validate the technology through the appropriate environmental authorities.

In summary, a new technology has emerged that can potentially provide an economic and environmentally benign way to capture and destroy methyl bromide that continues to be used under the exemptions from phase-out for emergency use, critical use, and quarantine/preshipment (QPS). QPS applications such as fumigation of perishable commodities are particularly well suited to this technology because of the limited time available to accomplish dockside fumigations. The method is based on applying reactive scrubber technology to totally remove highly reactive methyl bromide and convert it to environmentally benign products. The gas—liquid contact times are on the order of seconds. Patent applications have been submitted.

Last Updated: April 9, 2004