Enhanced Recovery of the Explosive Hexahydro-1,3,5-Trinitro-1,3,5-Triazine (RDX) From Soil: cyclodextrin versus anionic surfactants.

The extraction of RDX (I) from soil (1,000 ppm) was studied using 10 mL volumes of water and 1 % w/v aqueous solutions of sodium dodecyl sulfate (SDS), sodium lignosulfonate (Lignisite 458), Lignosol, hydroxypropyl-B-cyclodextrin (hp-B-CD), and methyl-B-cyclodextrin (Me-B-CD). The anionic surfactants SDS, Ligniste 458 and Lignosol increased RDX recovery to 1.2, 2.0 and 1.6- fold that of water (37.7 ppm), respectively. Extracted RDX was accompanied by hydrolysis as evidenced by the formation of 3,5-dinitro-1,3,5-triazacyclohex-l-ene (II). Similar RDX recoveries were obtained using the cyclodextrins hp-B-CD and Me-B-CD, i.e., 2.4 and l.5- fold that of pure water, respectively. In contrast to the ionic additives no RDX hydrolyzed products were observed during the cyclodextrin assisted extraction. In one case we found that RDX recovery from the soil increased with the concentration of the cyclodextrin and reached a value of 95% (ca 4.5- fold that of water) when a 10 % w/v solution of hp-B-CD was used.