Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2009. / Includes bibliographical references (p. 132-146).

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains ix, 116 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin, 1966. / Vita. Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

In order to investigate the relative merits of a selective oxidant for the degradation of natural polymers, humic acid extracts from three Alberta soil sites and three British Columbia soil sites, and two Kraft's prepared wood lignins were oxidized with 1.6 N NaOCl at room temperature (23°C) for 5 days. The oxidation products included CO₂, highly volatile acids and organic solvent soluble (OSS) products with the relative size of each fraction determined by carbon content. OSS products were characterized by Infrared (IR), Thin Layer Chromatography (TLC) and Nuclear Magnetic Resonance (NMR) techniques and identified after methylation and separation by Gas Liquid Chromatography (GLC) methods involving co-injecting authentic compounds and matching elution time and temperature of some of the components with that of the authentic compounds. Proceeding from the known chemistry of the NaOCl reaction, the CO₂ and highly volatile acid products could only be derived from the aliphatic chain or saturated ring components of humic acids or lignin and represented 66 to 82% of the products assuming no destruction of aromatic structure. Benzene carboxylic acid products were derived from the aromatic component of the starting materials. Estimates of the degree of aromaticity of the starting materials, using GLC and potentiometric titration data, were substantially less than those calculated from proposed model humic acid and lignin structures in the soils literature. An unidentified oily component was found in the oxidation products of two of the humic acid preparations. The results of this study indicated humic acid and lignin are composed of a mixed aliphatic-aromatic compound system. The relatively more mature humic acid preparations were found to be of greater aromaticity than the less mature samples. It was found 2 that NaOCl was not totally selective in differentiating Sp² from Sp³ carbon hybrids; as a result the total discrimination between aliphatic and aromatic structures was not a safe assumption. It is postulated that aromatic ring opening may occur at sites of hydroxyl group substitution on the ring structures resulting in an apparent less aromaticity and the generation / Land and Food Systems, Faculty of / Graduate

The favoured option for disposal of low and intermediate level radioactive waste is burial deep underground. In the safety assessment of deep disposal facilities a possibility which has to be considered is the eventual penetration of the engineered and natural barriers by ground water. Unfortunately humic and fulvic acids, present in most natural waters, can combine with radionuclides to produce metal complexes which are potentially more mobile in the environment than the original radionuclides from which they are formed. Migration of such complexes via groundwater and/or subsequently surface water routes could result in accelerated release of radionuclides to the biosphere. Quantitative knowledge of the extent of possible metal humate and fulvate interactions is therefore of considerable importance. In this study the complexation of Ni, Eu and Ce by humic and fulvic acids present in both ground and surface waters has been investigated. In most studies, to simplify the chemistry involved, humics and fulvics are separated from the water in which they occur before determination of their complexation properties. However, the severe conditions employed in the extraction process could conceivably alter the very properties to be measured. Accordingly the complexation properties of humics and fulvics present in a surface water have been studied both before and after extraction. The major part of this study was undertaken using a High Performance Size Exclusion Chromatographic technique especially developed to facilitate determinations on nonextracted materials. A fluorescence technique was also investigated as a more rapid alternative but was found to be of limited applicability. Complexation parameters were derived using a strong and weak site model. The effects of side reactions, ionic strength, pH, ligand type and nature of the cation were taken into account. With respect to measured stability constants, no major differences between ground and surface waters or extracted and non extracted materials were found. However, measured capacities of humics and fulvics for metals showed some variation according to the nature of the material and the system.

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Thesis (Ph. D.)--Ohio State University, 2004. / Document formatted into pages; contains xiv, 143 p. Includes bibliographical references. Abstract available online via OhioLINK's ETD Center; full text release delayed at author's request until 2005 June 21.

Thesis (Ph. D.)--University of Washington, 1995. / Vita. Includes bibliographical references (leaves [186]-201).

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