Towards a novel methodology for the environmental remediation of oil-polluted aqueous systems

Aromatic hydrocarbons are a prevalent constituent of crude oil. The refined products of crude oil such as petroleum and diesel can find their way into groundwater though oil-spillages and are also present in the oil and gas industry’s produced water. These aromatics are biorecalcitrant, however upon ingestion with water, may be metabolised to toxic intermediates that are carcinogenic or mutagenic in nature. Although some treatment technologies are available most of these are under development and are yet to be proven in the field. This illustrates the need for novel, economical and environmentally friendly technologies to be developed with a view to remediating aqueous systems that have been polluted with aromatics hydrocarbons. The supramolecular cyclodextrin molecule, with its hydrophobic interior and hydrophobic exterior seems to be an excellent molecule for the trapping of the pollutant molecules, however the inclusion complexes with this cyclic sugar are water-soluble therefore there is a need for the cyclodextrin to be rendered waterinsoluble. A study of the aqueous solubilities of some aromatic hydrocarbons that may be present in crude oil has been carried out and shows that the majority of these molecules have a degree of water solubility that may increase upon environmental weathering. The successful reaction between a solid-phase resin and the β-cyclodextrin molecule has been achieved, with the total dryness of the system being required including Soxhlet extraction of the resin with anhydrous acetone before the reaction. The reaction between β-cyclodextrin and a range of isocyanates proved unsuccessful, but a range of symmetrical aryl ureas were synthesised from their isocyanates with the influence that different activating or deactivating groups on the ring have on the propensity to form the ureas being shown. The successful alkylation between β-cyclodextrin and a series of haloalkanes has shown the effect of increasing chain length on the degree of alkylation. This reaction involved the deprotonation of the cyclodextrin by sodium hydride in anhydrous dimethyl sulphoxide followed by reaction with the alkyl iodide. Increasing the equivalents of hydride or iodide, or the reaction time did not have a noticeable effect on the degree of reaction indicating that steric constraints were limiting the degree of reaction. Testing several of these alkyl iodides gave an indication as to their tendency to uptake and remove several model pollutants that had been dissolved in water with the propylated β-cyclodextrin displaying potential for the remediation of aqueous systems that had been polluted. Several of these results were very promising leading to the conclusion that further derivatives of these alkylated sugars may be even more suitable for future research into the remediation of organically polluted aqueous systems.EThOS - Electronic Theses Online ServiceGBUnited Kingdo