摘要: |
Nitro-aromatics 2,4,6-trinitrotoluene (TNT) and hexahydro 1 ,3,5- trinitro-triazine (RDX) are the major constituents of wastewaters discharged from munitions load, assembly, and pack operations at Department of Defense (DOD) facilities. TNT and RDX enter wastestreams during munitions loading and demilitarization. This study focused on a treatment method for RDX. Prior work has shown that simple photolysis using ultraviolet light (UV) is sufficient to convert RDX in contaminated water to small non-nitrated organic by-products such as formaldehyde and formic acid, as well as the inorganic ions nitrate and nitrite. This implies that UV photolysis might provide a satisfactory and economical treatment system for RDX in water. The objectives of this project were to postulate a mechanism for RDX photolysis based on information from the literature and data obtained during this study, develop the corresponding kinetic model, and compare projections with results from laboratory photolysis and thermolysis experiments, for the purpose of verifying the model's appropriateness, finding the primary mechanistic steps in RDX photolysis and determining whether the reductive pathway contributes significantly to RDX degradation. Modeling results indicated that, of the possible pathways given in the literature, the primary photolysis pathway to the nitroso derivative in aqueous solution was scission of the N-N bond, eliminating the NO2 group. |