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|Title:||Transformation of 2,4,6,-trinitrotoluene under controlled Eh/pH conditions|
Installation Restoration Research Program (U.S.)
Price, Cynthia B.
Brannon, James M.
Hayes, Charolett A.
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: The presence of 2,4,6-trinitrotoluene (TNT) in soil and groundwater can present serious environmental problems. The processes that control the mobility and transformation of TNT in these environments are not well understood. The objective of this study was to determine the effects of redox potential (Eh) and pH on the transformation of TNT. Soil components responsible for the transformation of TNT were also investigated. Laboratory investigations included testing at four different redox potentials and four pH levels. A 10:1 (water:soil) suspension spiked with 100 μg of TNT/g, dry weight soil was used. The aqueous phase was sampled over a 2-week period for TNT and its transformation products. Soils were analyzed at completion of the 2-week incubation period. Results showed that redox potential and pH of the soil suspensions had a marked effect on TNT stability and transformation. The TNT was not stable under any Eh/pH conditions. TNT was least stable at any pH under highly reduced conditions. Results indicated that TNT persisted only under moderately reducing conditions and at lower pH levels. Soil component studies showed that the presence of Fe+2 sorbed to surfaces may explain the rapid disappearance of TNT from solution under highly reduced conditions (-150 mV). Radiolabeled TNT recovery tests in the Eh/pH reactors showed that added TNT was not lost from the system in significant quantities. Soil extraction recovered only a small portion of the added TNT, and azoxy compounds were not found, indicating that the products of TNT degradation were bound to the soil in unknown and perhaps unextractable forms. The data obtained in this study indicate that TNT in groundwater moving into an area of intense reduction would not persist. The TNT would be rapidly transformed into mono and diarmino compounds, which disappear from solution and soil.
|Appears in Collections:||Technical Report|