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Title: RDX and HMX sorption in thin disk soil columns
Authors: Louisiana State University (Baton Rouge, La.)
Installation Restoration Research Program (U.S.)
Townsend, Daniel M.
Adrian, Donald D.
Myers, Tommy E.
Keywords: Breakthrough curves
Soil pollution
Soil contamination
Environmental aspects
Publisher: Environmental Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Miscellaneous Paper
Abstract: Subsurface contarnhation by 2,3,5-trinitro-1,3,5-triazine (RDX) and oxyhydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) has prompted remediation and containment efforts at many Army installations. To fully evaluate the potential for natural attenuation to eliminate or substantially reduce remediation requirements, information on sorption and natural disappearance is needed. This study was conducted to determine RDX and HMX sorption and disappearance coefficients from breakthrough curves (BTCS) for three soils -- a silt loam, a clay, and Ottawa sand. Thin disk soil columns (0.32-cm soil length) were used to obtain RDX and HMX BTCS. Approximately symmetrical RDX and HMX BTCS were obtained for each soil. The BTCS were modeled assuming complete-mixing, first-order disappearance, and linear equilibrium sorption. This model produced excellent curve fits, with only slight discrepancies between the model and the observed data. Good mass balances were observed for both RDX (102 to 105 percent) and HMX (102 to 110 percent). RDX and HMX tended to sorb weakly to the soils used in this study. Linear equilibrium distribution coefficients for RDX ranged from 1.35 to 5.7 L/kg. Linear equilibrium distribution coefficients for HMX ranged from 1.45 to 8.5 L/kg. Although a linear equilibrium model could be used to simulate RDX and HMX sorption in the soils, a planned interruption in flow during the otherwise continuous flow experiments revealed evidence of nonequilibrium conditions in the clay and silt. Nonequilibrium effects were more pronounced in the clay than in the silt. BTCS and mass balances indicated that transformation and irreversible soil binding of RDX and HMX were minimal in these studies.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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