To comply with Federal and local regulations arising from the Clean Air Act Amendments of 1990, the Department of Defense (DoD) needs to develop innovative, safe, and environmentally acceptable alternatives to open burning/ open detonation (OB/OD) for the destruction of explosives in stockpiles and the demilitarization of obsolete weapons systems components.

This basic research project seeks to isolate naturally occurring enzymes capable of degrading chemical constituents of explosives in aqueous solution (by hydrolysis or redox). These enzymes then could be utilized in a low-cost system for energetics stabilization or destruction.

TNT Concentrations as Function of Time 

Enzymes exhibit very specific chemical reactivity which may be employed to attack target groups and thus degrade explosives molecules, even though they are not naturally occurring substrates. Enzymatic processes are robust, take place under ambient reaction conditions, and are able to withstand high concentrations of reactants, products, and other weapons components.

Extracts from sources such as spinach leaves, buttermilk, and Escherichia coli membranes have provided enzymes that are able to degrade nitro-aromatics. Enzymatic reduction of trinitrotoluene (TNT) led to the formation of 4-hydroxylamino-2,6-dinitrotoluene as a major intermediate. This compound has many potential industrial uses and its recovery and re-use may be economically viable. In a parallel effort using chemicals to mimic the enzymatic activity, potassium superoxide has been found capable of rapidly destroying the nitramines RDX and HMX under mild reaction conditions. This project was completed in FY 2000.

This project will yield environmentally benign alternatives to OB/OD, as well as possibly yield value-added products which could be used as raw materials by the chemical industry. Low-cost mobile reactors are conceivable for conducting demilitarization operations at a variety of sites.