Dissolution kinetics of high explosives particles in a saturated sandy soil

Solid phase high explosive (HE) residues from munitions detonation may be a persistent source of soil and groundwater contamination at military training ranges. Saturated soil column tests were conducted to observe the dissolution behavior of individual components (RDX, HMX, and TNT) from two HE formulations (Comp B and C4). HE particles dissolved readily, with higher velocities yielding higher dissolution rates, higher mass transfer coefficients, and lower effluent concentrations. Effluent concentrations were below solubility limits for all components at superficial velocities of 10-50 cm day(-1). Under continuous flow at 50 cm day(-1), RDX dissolution rates from Comp B and C4 were 34.6 and 97.6 microg h(-1) cm(-2) (based on initial RDX surface area), respectively, significantly lower than previously reported dissolution rates. Cycling between flow and no-flow conditions had a small effect on the dissolution rates and effluent concentrations; however, TNT dissolution from Comp B was enhanced under intermittent-flow conditions. A model that includes advection, dispersion, and film transfer resistance was developed to estimate the steady-state effluent concentrations.     

Soxhlet extraction of organic compounds associated with soil water repellency

The study of compounds associated with soil water repellency usually involves removing organic material from a sample by some extraction procedure. An evaluation of the kinetics and efficiency of Soxhlet extraction using an isopropanol-aqueous ammonia mixture is given here. Increasing extraction time caused an increase in the mass of material extracted and a decrease in soil water repellency. The same compound types were detected by gas chromatography-mass spectrometry in all extracts, but their proportions varied with extraction time. In particular, the removal of alkanes from the soil sample was less rapid than that of more polar compounds.