Thesis (M.S.)--University of Wisconsin--Madison, 1964. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 77-82.

Humic materials were chlorinated with sodium hypochlorite in basic solutions. The varied production of chloroform obtained from these compounds led to an investigation on the structure of humic substances. High pressure hydrogenation of a humic acid utilizing molybdenum-sulfide as a catalyst resulted in only a 26% yield of non-gaseous products. Spectral analysis of the residue indicated it to be composed of a mixture of highly aliphatically substituted aromatic oils. Separation of the components was unsuccessful via conventional techniques. The apparent destruction of the molecule led to an investigation of intact humic substances utilizing nuclear magnetic resonance (NMR). Proton NMR analysis of underivatized humic acids was complicated by the presence of paramagnetic iron. Removal of the iron resulted in poorly defined spectra. ¹³C NMR analysis resulted in absorptions from all the known functional groups of humic acids. The availability of ash free humic and fulvic acids led to the use of basic solutions as solvents in obtaining NMR spectra. The free radical nature of these solutions resulted in a study of ortho-quinone precursors by ¹³C NMR. Broadening of lines, loss of intensity, and shifting or absence of absorptions was noted in the basic ¹³C NMR spectra of catechol, catechin, quercetin, rutin, tannic acid, and fulvic acid when compared to the corresponding neutral spectra. Electron spin resonance studies indicated the existence of a quinone-radical equilibrium in the model compounds. The drastic differences observed upon introduction of the radical perturbs interpretation of ¹³C-NMR spectra on basic solutions of humic substances. Solid-state ¹³C-NMR analysis on humic substances appeared as an auspicious alternative. Magic-angle spinning alone proved useless with all but the most molecularly mobile solids such as polyisoprene. Since hydroxyl functionally plays an important role in the chemical properties of humic substances, derivatization with subsequent ¹³C-NMR analysis of these functional groups was undertaken. A dimethylation procedure utilizing first diazomethane followed by methyl iodide and sodium hydride was found to give complete methylation. This derivatization with ¹³C-enriched methyl precursors labels hydroxyl groups, eliminates hydrogen bonding and enhances signal assignment in the ¹³C-NMR spectra. Estimation of functional group types can also be inferred from integral absorptions. Since this method is direct and nondegradative, ¹³C-NMR relaxation studies can be used to give information on molecular size. The long T₁ values determined on methylated fulvic and humic acids are not characteristic of high molecular weight compounds, but are more appropriate for an aggregate of small units. This procedure completely characterizes hydroxyl functionality in these amorphous molecules and can therefore be used to characterize a whole range of oxygen containing macromolecules such as coal, shale oil, and lignins.

No description available.

The main issue of this thesis was to obtain information ondiffusion and sorption behaviour on organic colloids incompacted bentonite through experimental studies. It was tostudy if bentonite is an efficient barrier for organic colloidsor not. If colloids diffuse into bentonite in sufficientconcentrations, the speciation and sorption characteristics ofdiffusing radionuclides will change. Colloids might facilitatetransport, especially of radionuclides immobilised by strongsorption on bentonite. Laboratory experiments were performed to determine thestability of humic substances (HS) and bentonite colloids insolutions of ionic strengths representative for deep graniticgroundwaters. The HS but not the bentonite colloids were foundto be stable in these conditions. The competition between complexation with HS and sorption onbentonite of the cations Sr(II) and Eu(III) were studied inbatch experiments. Eu(III) was foundto complex with HS to bigextent. If HS is present in sufficient concentrations andstable in compacted bentonite, the Eu(III)-HS will be a speciesthat has to be accounted for. Sr(II) sorption decreases in thepresence of HS at ionic strength 0.01 M, but not at 0.1 M.Sr(II) sorbs weakly on bentonite and forms weak complexes withHS. The diffusion of Sr(II) in bentonite compacted to 1.8 g/cm3dry density and equilibrated with 0.1 M NaClO4 solutions wasstudied with and without HS in the system. The HS concentrationwas varied between 0.1 and 0.2 g/l. The Sr(II) diffusion wasnot affected by the presence of HS, which is in agreement withthe competition data of complexation to HS and sorption onbentonite. Diffusion of Co(II) and Eu(III) was studied in bentonite ofcompaction 0.6-1.8 g/cm3in the presence of HS. Eu(III)diffusion without HS in the system was studied as well. Co(II)diffusivity was found to increase significantly in the presenceof HS and the Kd-values decreased drastically. The decrease inthe Kd-values was found to be ionic strength dependent. This isexplained by HS complexation capacity decreases with increasingionic strength. The results indicate that the strongly surfacecomplexed Co(II) is mobilised by HS, but the Co-HS is not theonly diffusing Co(II) species in the experimental conditions ofthis study. Considering that Eu(III) sorbs strongly on bentonite, thediffusivity of Eu(III) was found to be rather high at ionicstrength 0.01 M. The high diffusivity rates are explained bythat the cation-exchanged Eu(III) around 1 % of the totalsorption is in practise mobile. In the presence of HS, Eu(III)diffusivity increases and the sorption decrease drastically.The Eu(III)-HS seems to be the dominating Eu(III) species whenthe HS concentrations are sufficiently high, and the HSsorption and diffusivity govern the system. <b>Keywords:</b>Diffusion, sorption, complexation, stability,bentonite, humic substances, Sr(II), Co(II) and Eu(III).

Polycyclic aromatic hydrocarbons (PAHs) are in general characterized by high toxicity, persistance, and bio-accumulation in environment. It is important to understand the transport and fate of PAHs in environment. In aquatic environment, PAHs are easily bound with dissolved organic matter (DOM), such as humic substance, and KDOC is usually used in denoting the binding constant. Previously, many investigations focused on the binding of a single PAH to DOM. However, few researches considered the competition effect on the binding of multiple PAHs to DOM. This study therefore explored the competition between the binary PAHs, pyrene and phenanthrene, in binding with humic substances. No significant competition effect in KDOC could be observed between these two compounds with LHA (Leonardite Humic Acid) because of the relatively large variation in KDOC determination. Humic substances from different sources might have different properties. Several characteristic indicators of humic substances were used to interprete the variations of KDOC of pyrene and phenanthrene, such as elemental ratio, total acidity, functional group content, etc. Negative correlations of O/C and phenolic group content to the KDOC of pyrene and phenanthrene were observed (p<0.05). In contrast, positive correlation of aromaticity and £`280 of humic substance to the KDOC of pyrene and phenanthrene were observed (p<0.05). Therefore, the contents of phenolic and aromatic groups of humic substance are essential factors in determining their binding constants with PAHs.

<p>The main issue of this thesis was to obtain information ondiffusion and sorption behaviour on organic colloids incompacted bentonite through experimental studies. It was tostudy if bentonite is an efficient barrier for organic colloidsor not. If colloids diffuse into bentonite in sufficientconcentrations, the speciation and sorption characteristics ofdiffusing radionuclides will change. Colloids might facilitatetransport, especially of radionuclides immobilised by strongsorption on bentonite.</p><p>Laboratory experiments were performed to determine thestability of humic substances (HS) and bentonite colloids insolutions of ionic strengths representative for deep graniticgroundwaters. The HS but not the bentonite colloids were foundto be stable in these conditions.</p><p>The competition between complexation with HS and sorption onbentonite of the cations Sr(II) and Eu(III) were studied inbatch experiments. Eu(III) was foundto complex with HS to bigextent. If HS is present in sufficient concentrations andstable in compacted bentonite, the Eu(III)-HS will be a speciesthat has to be accounted for. Sr(II) sorption decreases in thepresence of HS at ionic strength 0.01 M, but not at 0.1 M.Sr(II) sorbs weakly on bentonite and forms weak complexes withHS.</p><p>The diffusion of Sr(II) in bentonite compacted to 1.8 g/cm3dry density and equilibrated with 0.1 M NaClO4 solutions wasstudied with and without HS in the system. The HS concentrationwas varied between 0.1 and 0.2 g/l. The Sr(II) diffusion wasnot affected by the presence of HS, which is in agreement withthe competition data of complexation to HS and sorption onbentonite.</p><p>Diffusion of Co(II) and Eu(III) was studied in bentonite ofcompaction 0.6-1.8 g/cm3in the presence of HS. Eu(III)diffusion without HS in the system was studied as well. Co(II)diffusivity was found to increase significantly in the presenceof HS and the Kd-values decreased drastically. The decrease inthe Kd-values was found to be ionic strength dependent. This isexplained by HS complexation capacity decreases with increasingionic strength. The results indicate that the strongly surfacecomplexed Co(II) is mobilised by HS, but the Co-HS is not theonly diffusing Co(II) species in the experimental conditions ofthis study.</p><p>Considering that Eu(III) sorbs strongly on bentonite, thediffusivity of Eu(III) was found to be rather high at ionicstrength 0.01 M. The high diffusivity rates are explained bythat the cation-exchanged Eu(III) around 1 % of the totalsorption is in practise mobile. In the presence of HS, Eu(III)diffusivity increases and the sorption decrease drastically.The Eu(III)-HS seems to be the dominating Eu(III) species whenthe HS concentrations are sufficiently high, and the HSsorption and diffusivity govern the system.</p><p><b>Keywords:</b>Diffusion, sorption, complexation, stability,bentonite, humic substances, Sr(II), Co(II) and Eu(III).</p>

No description available.

Thesis (MScIng)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

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.