Enhanced Desorption of RDX from Granular Activated Carbon

Abstract

Several methods (cosolvents, surfactants, and cyclodextrins) were compared for improving desorption of a high explosive, RDX, from granular activated carbon (GAC). In batch desorption tests, 3% of the adsorbed RDX (initially 71.1 mg RDX/g GAC) was desorbed by water over 11 days, compared to 92.6% desorption by 100% ethanol. Solutions of ethanol or methanol in water also effectively desorbed RDX, although methanol was somewhat less effective than ethanol. Sodium dodecyl sulfate desorbed as much as 70% of the adsorbed RDX, while the non‐ionic surfactants Tween 80, Triton X‐100, and Brij 30 desorbed as much as 42 to 51% of the RDX. In continuous flow column tests, GAC was partially regenerated. One‐half of the adsorbed RDX was desorbed by 2100 bed volumes (BV) of 10% ethanol, compared to the 22 500 BV of buffered water. Column modeling indicated that competitive adsorption and altered equilibrium conditions combined to enhance RDX desorption.

Laboratory Studies and Preliminary Evaluation of Destructive Technologies for the Removal of RDX from the Water Waste Stream of Holston Army Ammunition Plan

“…The Army Environmental Command, along with EPA Region 10 and the Oregon Department of Environmental Quality, has set the characteristic hazardous waste status of explosives laden soils at 12% (Noyes 1996). Thermal regeneration of potentially explosive carbon is not recommended, though acetone (Fleming et al 1996) and ethanol (Morley et al 2005) have been studied as facilitators of RDX desorption from GAC. Solvent regeneration in this manner yields an RDX-laden solvent waste stream that must be treated, as well.…”

Microbial regeneration of spent activated carbon dispersed with organic contaminants: mechanism, efficiency, and kinetic models

“…Initial RDX concentrations were reduced from 1 mg/L to non-detectable levels in 4 days while HMX was consistently reduced from 0.6 mg/L to 0.4 mg/L. When coupled to removal from groundwater by adsorption, and subsequent desorption from GAC, the overall process could effectively increase the GAC service life and provide a permanent treatment method for RDX and HMX (Morley et al 2006).…”

Potential of activated carbon to recover randomly-methylated-β-cyclodextrin solution from washing water originating from in situ soil flushing

“…Recent studies rather looked into the potential of cyclodextrin to remove the adsorbed contaminants to regenerate AC. For example, Morley et al (2006) used different solubility enhancing agents such as cyclodextrins to remove the cyclotrimethylenetrinitramine or the explosive RDX sorbed on granular AC for its regeneration. However, since it is necessary to clean the water prior to reuse or discharge, more studies are necessary to ensure that cyclodextrin-hydrophobic contaminant inclusion complexes do not jeopardize the cleaning efficiency of AC.…”