Cyclodextrins for Desorption and Solubilization of 2,4,6-Trinitrotoluene and Its Metabolites from Soil

Abstract

Heptakis-2,6-di-O-methyl-β-cyclodextrin (DMβCD) and hydroxypropyl-β-cyclodextrin (HPβCD) (1% w/w solutions) were investigated for their ability to desorb 2,4,6-trinitrotoluene (TNT), 4-amino-2,6-dinitrotoluene (4-ADNT), and 2,4-diamino-4-nitrotoluene (2,4-DANT) from two artificially contaminated soils (an organic rich topsoil and an illite shale). The DMβCD (which is highly surface active) was more effective than HPβCD (negligible surface activity) for desorption of the three nitroaromatic compounds (NACs) from the two soils. The efficiency of both CDs for NAC removal from topsoil decreased with increasing amino substitution (i.e. TNT > 4-ADNT > 2,4-DANT), whereas for illite the efficiency generally decreased with increasing nitro substitution (i.e. TNT < 4-ADNT. 2,4-DANT). In general, the NAC removal efficiency increased with decreases in the sorption capacity constant (Kds). The two CDs were also assessed for their ability to remove TNT from a highly contaminated topsoil (5265 mg/kg) obtained from a for...