| Popis: |
The cyclic glucose oligosaccharides known as cyclodextrins (CDs) are able to form host-guest inclusion complexes with a variety of organic compounds including a number of pollutants. Substituted cyclodextrins in which one or more hydroxyl groups have been modified with, e.g. -CH3, -CH2CH(OH)CH3, -CH2COO−, -COO− and -SO 3 − , have many desirable properties compared with unmodified cyclodextrins, including greater aqueous solubility and binding ability. As part of studies on the abiotic degradation and soil-water interactions of pesticides and other hydrophobic organic compounds, in this work we have examined a number of substituted β-cyclodextrins for use as complexing agents for the enhancement of aqueous solubility of the organic pollutants trichloroethylene (TCE) and perchloroethylene (PCE). Solubility enhancement factors (Pt / P0) up to 5.5 and 14 were determined for trichloroethyelene and perchloroethyelene respectively. Binding constants for trichloroehylene with the substituted cyclodextrins, evaluated using 1H nuclear magnetic resonance (NMR), ranged from 3 M−1 to 120 M−1. In experiments with soil-derived peat contaminated by perchloroethylene and trichloroethylene, it was shown that selected cyclodextrins are capable of effective removal of the contaminants, suggesting that a suitably substituted β-cyclodextrin may be a valuable additive in pump-and-treat protocols for site remediation of poly-chlorinated organics. |
