Dissolution of composition B detonation residuals.

Area of Science:

• Environmental Science
• Chemical Engineering
• Geochemistry

Background:

• Composition B (Comp B) detonation residuals, containing hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and 2,4,6-trinitrotoluene (TNT), contaminate groundwater near U.S. Army training ranges.
• Understanding the dissolution behavior of these residuals on surface soils is crucial for environmental risk assessment and remediation strategies.

Purpose of the Study:

• To investigate the dissolution kinetics of RDX and TNT from individual Composition B particles under simulated rainfall conditions.
• To develop and validate models predicting the dissolution rates and environmental persistence of Comp B detonation residuals.

Main Methods:

• Controlled laboratory experiments dripping water onto individual Comp B particles (0.1-2.0 mg) collected from mortar detonations.
• Analysis of effluent to quantify dissolved RDX and TNT concentrations.
• Application and comparison of a steady-flow model and a novel drop-impingement model for dissolution prediction.

Main Results:

• RDX and TNT do not dissolve independently from Comp B; RDX dissolution rate limits the overall particle dissolution and TNT exposure.
• The developed drop-impingement model and a published steady-flow model accurately predicted dissolution behavior using RDX parameters.
• Dissolution times for Comp B particles (0.01-100 mg) under simulated rainfall (0.55 cm/h) are predicted to range from 6 to 600 days.

Conclusions:

• The dissolution of Comp B detonation residuals is controlled by the slower-dissolving RDX component.
• The developed models provide a framework for estimating the environmental persistence of explosives on soil surfaces.
• Further validation across diverse particle sizes and rainfall rates is needed to refine predictions for real-world scenarios.