The extraction and removal of 2,4-dinitrotoluene (2,4-DNT) from contaminated soils were evaluated using aqueous solutions of hydroxypropyl-β-cyclodextrin (HPCD). The cyclodextrin-enhanced removal of 2,4-DNT from soils was investigated as function of soil type and concentration of HPCD solutions up to 5% HPCD (w/w). Three soils were spiked with 480 mg of 2,4-DNT per kg of soil: kaolin, a low-buffering clayey soil; montmorillonite, a soil with high specific surface area; and glacial till, a high-buffering silty soil with organic matter. The glacial till was a field soil containing 2.8% organic matter. The solubility of 2,4-DNT in 5% HPCD solution increased approximately threefold compared to solubility of 2,4-DNT in water. For kaolin, water was as effective as HPCD solutions. For montmorillonite, the 5% HPCD solution was the most effective extractant. For glacial till, the 2% HPCD solution was as effective an extractant as the 5% HPCD solution. Although the solubility of 2,4-DNT in 2% HPCD was enhanced approximately 1.7-fold, the extraction of 2,4-DNT from glacial till and montmorillonite using 2% HPCD was enhanced more than twofold in sequential extractions. Three-stage sequential extractions with 2% HPCD followed by two water rinse stages resulted in the removal of 75 and 64% of 2,4-DNT from the glacial till and montmorillonite soils, respectively, whereas five-stage sequential extractions with water alone removed 33 and 30% of 2,4-DNT from glacial till and montmorillonite, respectively. The sequential extraction results showed that the 2% HPCD solution was an effective extractant for remediation of soils with strong retention of 2,4-DNT.
