Complexation of Organic Guests and Coordination of Metal Ions by Cyclodextrins: Role of Cyclodextrins in Metal-Guest Interactions.

摘要

Nitroaromatic explosives, such as trinitrotoluene (TNT), are of particular environmental concern due to their recalcitrance in soils and their potent toxicity and mutagenicity to both aquatic and mammalian species. TNT was the most widely used military explosive through the era encompassing both the First and Second World Wars. As a result, there is widespread contamination of soils by TNT around weapons manufacture, testing, and disposal facilities. Fenton chemistry (ferrous ion catalyzed generation of hydroxyl radicals) has shown utility in the remediation of TNT in soils but it suffers from non-specificity and the need for acidic conditions to prevent loss of iron as iron hydroxides. Cyclodextrins (CDs) have demonstrated the ability to increase the efficiency of Fenton degradation of aromatic pollutant species. The increase in degradation efficiency observed in the CD Fenton reaction systems has been credited to the formation of a pollutant/CD/ferrous ion ternary complex which has the ability to produce hydroxyl radicals at the site of bound ferrous ions during Fenton reactions. This results in an increase in hydroxyl radical concentration near the target guest molecule relative to the bulk solution, leading to a targeted degradation of the complexed guest molecule. In order to assess the viability of CD assisted Fenton reactions for the remediation of TNT, a thorough knowledge of the kinetics, degradation products, and role of binary and ternary complexes is required. Research presented in this dissertation examined the role of CDs in the Fenton oxidation of TNT, specifically: 1) the kinetics of TNT degradation in the presence of CDs for a Fenton reaction system, 2) the products of these reactions through chromatographic and mass spectrometric methods, and 3) NMR and binding studies of binary and ternary complexes.;Keywords: TNT, Nitroaromatic, Cyclodextrin, Fenton, Remediation