Solubilisation of chlorinated solvents by cyclodextrin derivatives

The capacity of α-cyclodextrin (α-CD) and four β-cyclodextrins (β-CDs) in reducing the volatility of volatile organic compounds (VOCs) and particularly carbon tetrachloride (CT), chloroform (TCM) and dichloromethane (DCM) is investigated by using static headspace gas chromatography (HSGC). The experiments allowed the determination of Henry's law constant (Hc) in absence and in presence of cyclodextrins (CDs). The use of CDs may lead to a reduction of 95% of the Henry's law constant for some VOCs. The association constants of the inclusion complexes formed between CDs and the three guests are determined using a new method involving an algorithmic treatment bringing the shortening of experimental time required for the determination of the stability constant. The complementarities of the host and the guest are investigated by molecular modelling. The complexation energies obtained are in good agreement with the experimental formation constants. Furthermore, this study shows the effectiveness of CDs in trapping pollutants and reducing their volatility in the viewpoint of pollution prevention.