Thesis (M.Ch.E.)--University of Delaware, 2008. / Principal faculty advisor: Douglas J. Buttrey, Dept. of Chemical Engineering. Includes bibliographical references.

The identification and subsequent treatment of contaminated land and groundwater is currently being regulated by the Environment Agency. The closure of gasworks sites during the late 1960s left areas of land contaminated with undesirable residues of the manufactured gas process, which were left to cause further pollution by leaching into surface and groundwater. The techniques available to remediate these contaminated media are numerous, but most tend to suffer from at least one major disadvantage, usually time or cost.

Five models, ranging from a full molecular polar/polarizable model with C₃v symmetry, to the primitive model of ions in a dielectric continuum, have been used to study the properties of ammonia both as a pure liquid and as a solvent. Ammonia is modelled as a multipolar polaxizable hard sphere and ions as charged hard spheres. Using these models, in conduction with the Reference Hypernetted-chain integral equation theory, ammonia has been studied as a pure liquid, as a solvent near charged and uncharged surfaces, and in electrolyte solutions of finite concentration. The formalism of Kirkwood and Buff was used to obtain thermodynamic quantities of ionic solutions from calculated distribution functions. Structural, thermodynamic and. dielectric properties were calculated for pure ammonia and were compared with experiments where possible. Values for the dielectric constant and the configurational energy were found to compare favorably with experiment. Ammonia formed a relatively dense, highly structured layer within two solvent diameters of an uncharged surface. This structure was analyzed in terms of angular probability distributions of the molecular dipole vector and the NH-bond direction, and was found to be similar to that of frozen ammonia. The extreme asymmetry of solvation of unlike charges in ammonia was also investigated. Small cations were found to be more favorably solvated than small anions, but as the ion size was increased, the situation reversed. Estimates of the number of ion pairs in liquid ammonia and their effects on the behavior of mean molar activity coefficients were examined. Large differences between experimental activity coefficients and the Debye-Hückel hmiting law could not be explained by the usual ideas of ion pairing. It was found that the integral equation theories appear to have no solution between ionic concentrations of about 2 x 10⁻⁴M and 2 x 10⁻²M for either molecular or continuum models. Using rigorous stability criteria, this behavior was shown to be consistent with the onset of a phase change. It is proposed that such phase separation phenomena might explain the unusual behavior of the experimental activity coefficients. / Science, Faculty of / Chemistry, Department of / Graduate

The conversion of ammonia to 2:4-dinitroaniline by reaction with 1-fluoro, 2:4-dinitrobenzene and the subsequent conversion of dinitroaniline to a diazo-dye with N-(1-naphthyl)ethylenediamine has been investigated as an analytical method for determining ammonia at the micromolar concentration level. Particular emphasis was placed upon the possibility of applying this method to the analysis of sea water. Dinitroaniline was formed under alkaline conditions (pH greater than 8) and required the presence of the fluoro-dinitrobenzene as a separate phase for initiation of the reaction. The conversion, which was light sensitive, was accelerated by increases in pH and temperature, but neither of these factors improved the final yield. The yield of dinitroaniline had a marked dependence on the amount of fluorodinitrobenzene; initially increasing with increasing fluorodinitro-benzene content, it then decreased with higher fluorodinitrobenzene concentrations suggesting further reaction between dinitroaniline and fluorodinitrobenzene. In both distilled and sea water, the maximum yield of dinitroaniline from solutions containing ammonia at the micromolar concentration level was found to be 55-58%. The absorbance of the diazo-dye in sea water of salinity 30.4% was only 42% of that observed in distilled water. Although sufficiently sensitive for application to sea water analysis, the precision of the conversion of dinitroaniline to the diazo-dye in sea water was poor compared to that achieved in distilled water. / Science, Faculty of / Chemistry, Department of / Graduate

Bibliography: pages 181-201. / A genomic library of the collagenolytic Vibrio alginolyticus strain was established in Escherichia coli HB101 employing the positive selection vector pEcoR251. A glutamine synthetase (GS) gene, glnA was identified by complementation of the glnA deletion in E. coli ET8051 glnA, glnL, glnG deletion strain. The glnA region of V. alginolyticus was cloned on a 5.7 kb insert in pRM210.

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