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1
Alotaibi, Yousef. "Chemistry of humic-like substances in the atmosphere." Thesis, University of East Anglia, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405706.
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O'Loughlin, Edward John. "Association of organotin compounds with aquatic humic substances /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487946776023338.
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Kumke, Michael U., and Fritz Hartmann Frimmel. "Stationary and time-resolved fluorescence for humic substances characterization." Universität Potsdam, 2002. http://opus.kobv.de/ubp/volltexte/2007/1235/.
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Steady-state and time-resolved fluorescence methods were applied to investigate the fluorescence properties of humic substances of different origins. Using standard 2D emission and total luminescence spectra, fluorescence maxima, the width of the fluorescence band and a relative fluorescence quantum efficiency were determined.
Different trends for fulvic acids and humic acids were observed indicating differences in the heterogeneity of the sample fractions. The complexity of the fluorescence decay of humic substances is discussed and compared to simple model compounds.
The effect of oxidation of humic substances on their fluorescence properties is discussed as well.
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Kim, Jong-Soo. "Characteristics of humic substances and their removal behavior in water treatment." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/21469.
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Scanlon, M. M. "Some aspects of the interaction of humic substances with metal ions." Thesis, Aston University, 1991. http://publications.aston.ac.uk/9783/.
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Humic substances are the major organic constituents of soils and sediments. They are heterogeneous, polyfunctional, polydisperse, macromolecular and have no accurately known chemical structure. Their interactions with radionuclides are particularly important since they provide leaching mechanisms from disposal sites. The central theme to this research is the interaction of heavy metal actinide analogues with humic materials. Studies described focus on selected aspects of the characteristics and properties of humic substances. Some novel approaches to experiments and data analysis are pursued. Several humic substances are studied; all but one are humic acids, and those used most extensively were obtained commercially. Some routine characterisation techniques are applied to samples in the first instance. Humic substances are coloured, but their ultra-violet and visible absorption spectra are featureless. Yet, they fluoresce over a wide range of wavelengths. Enhanced fluorescence in the presence of luminescent europium(III) ions is explained by energy transfer from irradiated humic acid to the metal ion in a photophysical model. Nuclear magnetic resonance spectroscopy is applied to the study of humic acids and their complexes with heavy metals. Proton and carbon-13 NMR provides some structural and functionality information; Paramagnetic lanthanide ions affect these spectra. Some heavy metals are studied as NMR nuclei, but measurements are restricted by their sensitivity. A humic acid is fractionated yielding a broad molecular weight distribution. Electrophoretic mobilities and particle radii determined by Laser doppler electrophoretic Light Scattering are sensitive to the conditions of the supporting media, and the concentration and particle size distribution of humic substances. In potentiometric titrations of humate dispersions, the organic matter responds slowly and the mineral acid addition is buffered. Proton concentration data is modelled and a mechanism is proposed involving two key stages, both resulting in proton release after some conformational changes.
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Hale, Kerry Anne. "The formation, synthesis and reactions of humic polymers in chemical and biological systems." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329937.
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Kwon, Deokhyeon. "Optical and physicochemical properties of secondary organic aerosol and aerosol generated from humic substances." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6455.
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A great deal of attention has been paid to brown carbon aerosol in the troposphere because it can both scatter and absorb solar radiation, thus affecting the Earth’s climate. However, knowledge of the optical and chemical properties of brown carbon aerosol is still limited. In this thesis, we have investigated different aspects of the optical and physicochemical properties of various brown carbon aerosol samples of potential atmospheric importance.
First, reactions involving the di-carbonyl species methylglyoxal (MG) have been previously suggested as an important pathway for the production of secondary organic aerosol (SOA) in the atmosphere. Reaction in an aqueous inorganic salt solution, such as ammonium sulfate (AS), leads to the formation of light-absorbing brown carbon (BrC) product. In this thesis work, we employed a variety of experimental approaches to investigate the optical and physicochemical properties of BrC aerosol generated from this AS-MG reaction (BrC (AS/MG)). Optical properties of the dried BrC (AS/MG) aerosol particles were studied by Fourier transform infrared (FTIR) extinction spectroscopy in the mid-infrared region, cavity ring-down spectroscopy (CRDS) at 403 nm in the visible, and by measuring the light scattering phase function and polarization profiles at two different visible wavelengths, 532 and 402 nm. In addition, we used UV−vis spectroscopy to measure the mass absorption coefficient (MAC) of the solution-phase reaction products. The different optical properties were measured as a function of reaction time for a period of up to 22 days. The UV-vis absorption spectra showed a clear increase in measured MAC in the visible and near UV as the solution aged. However, analysis of the light scattering data showed no significant differences between AS and BrC aerosol in the derived refractive indices at either 532 or 402 nm, even for the longest reaction times. The FTIR extinction spectra was modeled in a Mie theory simulation to derive the complex refractive index in the mid-IR range (7000-800 cm−1); the results showed no significant changes in either the real or the imaginary parts of the refractive indices for BrC (AS/MG) aerosol particles when compared to unreacted AS aerosol. From the CRDS extinction data, the optical constants for BrC (AS/MG) particles at 403 nm were also determined through a Mie theory based analysis. The retrieved real index of refraction at 403 nm is n = 1.551 ± 0.005, with an imaginary index value of k = 0.000 ± 0.002; these values do not appear to change significantly with aging time over the course of 22 days and are not markedly different from the AS aerosol values. The small imaginary index value suggests that BrC (AS/MG) aerosol formed from this pathway may not significantly contribute to warming. In addition, CRDS measurements of the BrC (AS/MG) aerosol extinction at 403 nm as a function of particle size show a significant deviation from Mie theory simulations for particles with diameters of ≳500 nm, probably as a result of non-spherical particle shape effects. We also employed atomic force microscopy (AFM)-based IR spectroscopy to investigate the morphology and chemical composition of single SOA particles. AFM analysis of the particle morphology shows that a significant fraction of BrC (AS/MG) particles with diameters of ≳500 nm are non-spherical in shape, consistent with our observed breakdown in the applicability of Mie theory for larger particles. In addition to these measurements, we have characterized additional physicochemical properties of the BrC (AS/MG) aerosol particles including hygroscopic growth using a tandem-differential mobility analyzer. Compared to AS, BrC aerosol particles are found to have lower deliquescence relative humidity (DRH), efflorescence relative humidity (ERH), and hygroscopic growth at the same relative humidity values.
Second, we investigated the optical properties of the water soluble products of limonene BrC generated from ozonolysis of d-limonene with further aging by AS. Optical constants for the dried limonene BrC aerosol product were measured at 403 nm by CRDS over the course of 9 days of aging. While the fresh limonene BrC aerosol showed a significant non-zero absorption index, the aged samples showed absorption index values consistent with zero. This result was somewhat unexpected because UV-vis absorption spectra of the bulk reaction solution showed a continued increase in absorption as the solution aged. One possible explanation for this result is that there could be an increase in the fraction of volatile chromophores as the solution ages, that are then removed in the aerosol drying process.
Third, we investigated optical properties and chemical compositions of several humic substance (HS) reference samples including humic acid (HA) and fulvic acid (FA) standards by CRDS, UV-vis spectroscopy, elemental analysis, and 13C NMR spectroscopy. Measurements of the optical properties of HS is important in atmospheric science, because it is thought that HS samples have similar optical properties to organic materials, such as HUmic-Like Substances (HULIS), that exist in clouds, fogs, rainwater, and atmospheric aerosol. The humic acid aerosol samples generally showed higher absorption index values than the fulvic acid aerosol samples. We also found a correlation between the absorption index and chemical composition, with the value for k generally increasing with both increasing carbon-to-oxygen atomic ratio and sample aromaticity. In addition, we compared our measured optical constants for the HS aerosol samples with results from previous studies of field collected HULIS. The absorption index values for the fulvic acid aerosol samples give a better match than the humic acid samples when compared to the results from the field collected samples.
Overall, these studies provide new details of the optical and physicochemical properties of a class of brown carbon organic aerosol which may have important implications for atmospheric chemistry and climate.
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Kumke, Michael U., and Sascha Eidner. "Fluorescence and energy transfer processes of humic substances and related model compounds in terbium complexes." Universität Potsdam, 2005. http://opus.kobv.de/ubp/volltexte/2007/1225/.
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The fluorescence properties and the fluorescence quenching by Tb3+ of substituted benzoic acid were investigated in solution at different pH. The substituted benzoic acids were used as simple model compounds for chromophores present in humic substances (HS). It is shown that the fluorescence properties of the model compounds resemble fluorescence of HS quite well. A major factor determining the fluorescence of model compounds are proton transfer reactions in the electronically excited state. It is intriguing that the fluorescence of the model compounds was almost not quenched by Tb3+ while the HS fluorescence was decreased very effectively. From our results we concluded that proton transfer reactions as well as conformational reorientation processes play an important role in the fluorescence of HS. The luminescence of bound Tb3+ was sensitized by an energy transfer step upon excitation of the model compounds and of HS, respectively. For HS the observed sensitization was dependent on its origin indicating differences 1) in the connection between chromophores and
binding sites and 2) in the energy levels of the chromophore triplet states. Hence, the observed sensitization of the Tb3+ luminescence could be useful to characterize structural differences of HS in solution.
Interlanthanide energy transfer between Tb3+ and Nd3+ was used to determine the average distance R between both ions using the well-known formalism of luminescence resonance energy transfer. R was dependent on the origin of the HS reflecting the difference in structure. The value of Rmin seemed to be a unique feature of the HS. It was further found that upon variation of the pH R also changed. This demonstrates that the measurement of interlanthanide energy transfer can be used as a direct method to monitor conformational changes in HS.
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Gonzalez, Raymat Hansell. "Unrefined Humic Substances as a Potential Low-cost Remediation Method for Groundwater Contaminated with Uranium in Acidic Conditions." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3864.
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Anthropogenic activities such as uranium mining and milling, nuclear weapons production, and nuclear reprocessing have left a legacy of groundwater and soil contaminated with uranium that needs to be addressed. Therefore, developing new remediation technologies to sequester uranium in situ is crucial. The objective of the study was to determine if low-cost commercially available unrefined humic substances, such as Huma-K, can be used to facilitate uranium sorption to minerals in soil and sediment. Sediments from the saturated zone beneath the F-Area seepage basins at the Savannah River Site (SRS) in South Carolina were used for the present study. The SRS site is analogous to many contaminated locations where groundwater acidity enhances uranium and other contaminants mobility.
First, a variety of techniques were applied to characterize Huma-K and SRS sediment. Characterization studies showed that Huma-K possesses functional groups that have an acidic nature such as carboxyl and phenol groups. For SRS sediment, a mineral composition of mainly quartz (93.2%), kaolinite (5.1%), and goethite (1.1%) was identified.
Second, the interactions between Huma-K and SRS sediment were investigated through batch experiments. Sorption, homogeneous precipitation, and surfaced-induced precipitation were observed to be enhanced at pH 4. However, Huma-K removal from solution decreased with an increase of pH. The sorption behavior was not able to be described by any of the models employed (pseudo-first, pseudo-second, Langmuir, and Freundlich).
Third, the interactions between uranium and SRS sediment with and without Huma-K amendment were investigated. In acidic conditions (pH 3-5), the sorption capacity of SRS sediment amended with Huma-K was significantly increased compared to plain sediment. At circumneutral conditions, uranium removal from solution decreased for SRS sediment amended with Huma-K, compared with plain sediments, likely as a result of the formation of aqueous uranium-humic complexes. In summary, the results from the present study suggest that Huma-K, and likely other unrefined humate products, has the characteristics and effects necessary to be suitable for subsurface injection to remediate uranium in acidic groundwater conditions. The treatment zone will persist as long as the pH does not increase sufficiently to cause soil-bound Huma-K to be released, remobilizing uranium.
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Davis, Christina Clarkson. "Aqueous Silica in the Environment: Effects on Iron Hydroxide Surface Chemistry and Implications for Natural and Engineered Systems." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/33948.
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Aqueous silica is present in all natural waters and exhibits a high affinity for the surfaces of iron oxides. Therefore, it is expected to play an important role in environmental systems. Experiments were conducted to investigate the fundamentals of silica sorption onto pre-formed ferric hydroxide at pH 5.0-9.5 and silica concentrations of 0-200 mg/L as SiO2. Over the entire pH range studied, sorption densities exceeding monolayer sorption were observed at silica levels typical of natural waters. Under some circumstances, sorption exceeded a monolayer while the particle zeta potential remained positive, a phenomenon which is inconsistent with available models. To address this deficiency, an extended surface complexation model was formulated in which soluble dimeric silica sorbs directly to iron surface sites. This model fits sorption density data up to 0.40 mol SiO2/mol Fe, and it accurately predicts trends in zeta potential and the observed H+ release during silica sorption to ferric hydroxide at pH 5.0 and 6.0.
A second phase of research was aimed at identifying the practical implications of silica sorption to iron hydroxide in natural and engineered systems. Two types of surfaces were prepared by exposing pre-formed Fe(OH)3 to aqueous silica (0-200 mg/L as SiO2) for periods of 1.5 hours or 50 days. The concentration of pre-formed iron passing through a 0.45 micron pore size filter at pH 6.0-9.5 increased as the solids aged in the presence of silica. Consistent with formation of small, stable colloids, "soluble" iron concentrations exceeded 0.2 mg/L only at zeta potentials < -15 mV. When arsenate was added to iron hydroxide particles equilibrated with silica for 1.5 hours, percentage arsenate removals were high. In contrast, arsenate removals decreased markedly as pH and silica concentrations increased if silica was pre-equilibrated with the iron for 50 days. Trends in percentage removal of humic substances were similar. Competition for sorption sites was the main cause of hindered anionic contaminant removal. However, interference with hydrolysis and precipitation are expected to be important under some circumstances, particularly during water treatment.
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Kumke, Michael Uwe. "Huminstoffe und organische Modellliganden und ihre Wechselwirkung mit Metallionen und polyzyklischen aromatischen Kohlenwasserstoffen." Thesis, Universität Potsdam, 2005. http://opus.kobv.de/ubp/volltexte/2005/606/.
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Immobilisierung bzw. Mobilisierung und Transport von Schadstoffen in der Umwelt, besonders in den Kompartimenten Boden und Wasser, sind von fundamentaler Bedeutung für unser (Über)Leben auf der Erde. Einer der Hauptreaktionspartner für organische und anorganische Schadstoffe (Xenobiotika) in der Umwelt sind Huminstoffe (HS). HS sind Abbauprodukte pflanzlichen und tierischen Gewebes, die durch eine Kombination von chemischen und biologischen Ab- und Umbauprozessen entstehen. Bedingt durch ihre Genese stellen HS außerordentlich heterogene Stoffsysteme dar, die eine Palette von verschiedenartigen Wechselwirkungen mit Schadstoffen zeigen. Die Untersuchung der fundamentalen Wechselwirkungsmechanismen stellt ebenso wie deren quantitative Beschreibung höchste Anforderungen an die Untersuchungsmethoden. Zur qualitativen und quantitativen Charakterisierung der Wechselwirkungen zwischen HS und Xenobiotika werden demnach analytische Methoden benötigt, die bei der Untersuchung von extrem heterogenen Systemen aussagekräftige Daten zu liefern vermögen. Besonders spektroskopische Verfahren, wie z.B. lumineszenz-basierte Verfahren, besitzen neben der hervorragenden Selektivität und Sensitivität, auch eine Multidimensionalität (bei der Lumineszenz sind es die Beobachtungsgrößen Intensität IF, Anregungswellenlänge lex, Emissionswellenlänge lem und Fluoreszenzabklingzeit tF), die es gestattet, auch heterogene Systeme wie HS direkt zu untersuchen. Zur Charakterisierung können sowohl die intrinsischen Fluoreszenzeigenschaften der HS als auch die von speziell eingeführten Lumineszenzsonden verwendet werden. In beiden Fällen werden die zu Grunde liegenden fundamentalen Konzepte der Wechselwirkungen von HS mit Xenobiotika untersucht und charakterisiert.Für die intrinsische Fluoreszenz der HS konnte gezeigt werden, dass neben molekularen Strukturen besonders die Verknüpfung der Fluorophore im Gesamt-HS-Molekül von Bedeutung ist. Konformative Freiheit und die Nachbarschaft zu als Energieakzeptor fungierenden HS-eigenen Gruppen sind wichtige Komponenten für die Charakteristik der HS-Fluoreszenz. Die Löschung der intrinsischen Fluoreszenz durch Metallkomplexierung ist demnach auch das Resultat der veränderten konformativen Freiheit der HS durch die gebundenen Metallionen. Es zeigte sich, dass abhängig vom Metallion sowohl Löschung als auch Verstärkung der intrinsischen HS-Fluoreszenz beobachtet werden kann.
Als extrinsische Lumineszenzsonden mit wohl-charakterisierten photophysikalischen Eigenschaften wurden polyzyklische aromatische Kohlenwasserstoffe und Lanthanoid-Ionen eingesetzt. Durch Untersuchungen bei sehr niedrigen Temperaturen (10 K) konnte erstmals die Mikroumgebung von an HS gebundenen hydrophoben Xenobiotika untersucht werden. Im Vergleich mit Raumtemperaturexperimenten konnte gezeigt werden, dass hydrophobe Xenobiotika an HS-gebunden in einer Mikroumgebung, die in ihrer Polarität analog zu kurzkettigen Alkoholen ist, vorliegen. Für den Fall der Metallkomplexierung wurden Energietransferprozesse zwischen HS und Lanthanoidionen bzw. zwischen verschiedenen, gebundenen Lanthanoidionen untersucht. Basierend auf diesen Messungen können Aussagen über die beteiligten elektronischen Zustände der HS einerseits und Entfernungen von Metallbindungsstellen in HS selbst angeben werden. Es ist dabei zu beachten, dass die Experimente in Lösung bei realen Konzentrationen durchgeführt wurden. Aus Messung der Energietransferraten können direkte Aussagen über Konformationsänderungen bzw. Aggregationsprozesse von HS abgeleitet werden.
Transport and fate of xenobiotics in the environment, especially in water and soil, are of utmost importance for life on earth. A major reaction partner for xenobiotics in the environment are humic substances (HS). HS are degradation products of plant and animal tissue, which are formed in a combination of subsequent chemical and/or biochemical processes. Because of the complex history of their origin HS are extremely heterogeneous mixtures of different compounds. Consequently, they posses a great variety of interaction capabilities with various xenobiotics. The investigations of the fundamental interaction mechanisms between HS and xenobiotics make high demands on the analytical techniques used. Especially spectroscopic techniques are promising for the investigation of interaction mechanisms in complex systems. Luminescence spectroscopy has the great advantage of outstanding sensitivity and of multidimensionality, which in principle allows the investigation of HS under environmental relevant conditions. For the characterisation of interaction processes of HS with xenobiotics the intrinsic fluorescence of HS as well as the luminescence of extrinsic probes can be used.
The intrinsic HS fluorescence is determined by the molecular structure as well as the connection of the basic fluorophores. Conformational freedom as well as the presence of energy accepting groups in the neighbourhood of the fluorophores are highly important for the overall intrinsic HS fluorescence. The presence of metal ions can either quench or enhance the intrinsic HS fluorescence, which depends on the metal ion as well as on the origin of the HS investigated. While in most cases Al3+ ions enhance the intrinsic HS fluorescence, Ln3+ ions induce a fluorescence quenching.
Polycyclic aromatic hydrocarbons were used as extrinsic fluorescence probes in order to characterize the interaction of HS and hydrophobic organic xenobiotics. In investigations at ultra-low temperatures (10 K) it could be shown that pyrene is bound in a HS microenvironment with an polarity which resembles that of small alcohols (e.g., butanol).
In case of metal complexation, the lanthanide ions Eu3+ and Tb3+ were used as luminescence probes. Due to the outstanding luminescence properties of those ions, information about metal binding sites in HS were obtained. Based on the measurements of intramolecular and intermolecular energy transfer processes average distances of metal binding sites were deduced.
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Gullinkala, Tilak. "Evaluation of Poly (Ethylene Glycol) Grafting as a Tool for Improving Membrane Performance." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1271440380.
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Castro, Joseph Emmanuel 1962. "Model compound interactions characterizing aquatic humic substances." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277256.
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An attempt was made to simulate XAD-8 isolates of Orange County groundwater and Biscayne Aquifer groundwater using mixtures of single ligands. Mixtures of catechol, glycine, phthalic acid and salicylic acid were used to simulate potentiometric and complexometric titrations. Concentrations used for the mixtures were based on carboxylic acidity, dissolved organic carbon, and assumed values for phenolic acidity and nitrogen content. Potentiometric titrations were reproduced with mixtures of the ligands; however, complexometric titrations at pH 6.2 and pH 7.5 could not be duplicated. A stronger ligand was required to fit the pH 6.2 titrations, and higher carboxylic contents were needed for pH 7.5. At pH 6.2 70 percent of the binding sites were attributed to phthalic acid-type groups and 20 percent to catechol-type groups. At pH 7.5 greater than 98 percent was attributed to phthalic acid-type groups.
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Baiu, Saleh Hamed Salem. "Degradation of Humic Substances by Aquatic Bacteria." Thesis, North Texas State University, 1985. https://digital.library.unt.edu/ark:/67531/metadc331502/.
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A variety of aquatic bacteria were isolated and tested for their ability to degrade humic substances and their aromatic residues/monomers which serve as precursors of the trihalomethanes (THMs) found in chlorinated drinking waters. The majority of them were Gram-negative, oxidative types dominated by pseudomonads. Most of the 146 isolates were found to utilize as their sole source of carbon several or more of ten aromatic compounds known to be products of degradation of humus and also to be precursors of THMs. The aromatics tested, with percent of the isolates utilizing the compound in parentheses, were: p-hydroxybenzoate (49), vanillic acid (48), 3,5-dihydroxybenzoic acid (16), syringic acid (19), vanillin (30), benzoic acid (27), ferulic acid (34), resorcinol (9), catechol (8) and protocatechuic acid (27).
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Graham, Margaret C. "An investigation of actinide interactions with humic substances." Thesis, University of Glasgow, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360263.
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Palmer, Fiona Lorraine. "Photocatalysis of aquatic humic substances prior to chlorination." Thesis, University of Ulster, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263245.
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Inam, Edu. "Investigations of interactions of arsenic with humic substances." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/7719.
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Interest in arsenic in groundwater has greatly increased in the past decade because of the increased awareness of human health effects linked to prolonged drinking of untreated ground water supplies high in arsenic content. A number of studies on arsenic bioavailability in soils have linked the presence of organic matter to high arsenic content. The question of whether arsenic interacts with organic matter chemically becomes significant. The work reported in this thesis investigates the chemistry of arsenic interaction with humic acid which comprises 50 % of soil organic matter. The thesis begins with an overview of arsenic environmental chemistry including its signifitcance, distribution, metabolism and toxicity. A literature review outlines the aqueous chemistry of arsenic specifically speciation, adsorption and mobility. The first part of the study focuses on the investigation of arsenic humic acid reactions over a range of conditions, for example changes in pH and ionic strength. Hydrolysed species of inorganic arsenic M and (111), and an organic form of arsenic (CH3)2AsOOH, were employed. Results show that the extent of reaction generally increased with pH and decreased with ionic strength. The results were interpreted firstly by assuming simple association and then by postulating ligand exchange. The derived equilibrium constants showed weak arsenic interaction with humic acid. The second part of the study examined the identification of arsenic bearing phases in a reference soil sample and contaminated soil samples. The results were processed using Chemometric Identification of Substrates and Elements Distribution (CISED). The research concluded that arsenic was mainly associated with an iron oxide phase in soils.
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Samburova, Vera. "Characterization of Humic-like substances in atmospheric aerosol particles /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17282.
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Ertel, John Richard. "The lignin geochemistry of sedimentary and aquatic humic substances /." Thesis, Connect to this title online; UW restricted, 1985. http://hdl.handle.net/1773/11002.
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Milne, C. J. "Measurement and modelling of ion binding by humic substances." Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326970.
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Postill, Anthony S. "The interaction of trace metals with humic substances in estuaries." Thesis, Lancaster University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274193.
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Olds, William. "Lignite Derived Humic Substances for Treatment of Acid Mine Drainage." Thesis, University of Canterbury. Civil and Natural Resources, 2011. http://hdl.handle.net/10092/6583.
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Addition of alkalinity to acid mine drainage (AMD) results in the neutralisation of acidity and precipitation of dissolved metals as insoluble hydroxides. Two aspects of the current AMD treatment practice at the Stockton Mine could be enhanced. Firstly, residual water quality may be poor due to unreacted alkalinity reagents, particularly CaCO3, resulting in poor water clarity and elevated suspended solids (SS). Secondly, neutralisation to circum-neutral pH may not avoid the discharge of residual metals (Ni and Zn) due to incomplete adsorption and hydroxide precipitation.
The aim of this project was to enhance the conventional neutralisation of AMD through addition of humic substances (HS) to reduce residual SS and trace metal concentrations. Humic substances are organically derived and have a high molecular weight. Functional groups on the surface of HS are capable of binding dissolved metals, forming HS-metal complexes. Incorporation of HS complexed metals into settling floc could result in increased metal removal from the dissolved phase.
Modified jar testing was used to investigate the effects of HS addition before, after and during (pH 4.5) neutralisation of AMD in two treatment scenarios at the Stockton Mine; the Blackwater Treatment Plant (BTP) using NaOH and Ca(OH)2 and the Mangatini Stream-sump System (MSS) using CaCO3. Supernatant samples collected during the sedimentation period were analysed for basic water quality parameters (turbidity and suspended solids) and dissolved (< 0.45 µm) metal concentrations.
The addition of HS to the BTP process before (pH 2.8) and during (pH 4.5) neutralisation resulted in HS precipitation. Precipitated HS subsequently acted as a nucleation site, triggering flocculation of precipitating metal hydroxides, resulting in low turbidity and suspended solids (SS) of less than 2 NTU and 5 mg/L, respectively. The addition of HS after neutralisation (pH 7) did not result in HS precipitation. Intermolecular bridging of HS by the divalent Ca resulted in incorporation of HS into floc when neutralised by Ca(OH)2, resulting in low turbidity and SS. However, in NaOH neutralised conditions, the monovalent Na was unable to bridge HS molecules, resulting in HS remaining dissolved and contributing to elevated turbidity and SS of up to 24.4 NTU and 18.4, respectively.
The neutralisation efficiency of CaCO3 is relatively low, thus approximately 1000 mg/L CaCO3 remained unreacted in MSS scenarios, resulting in elevated turbidity and SS. When added after neutralisation, dissolved Solid Energy Humic Acid (SEHA) facilitated flocculation of residual CaCO3 SS, resulting in an up to 75% lower suspended solids than CaCO3 neutralisation alone conditions. Although the results are good, the efficiency of SEHA as a polymer compared unfavorably in a cost: benefit analysis to two commercially available polymers for the removal of residual CaCO3.
Neutralisation of AMD in control samples resulted in decreased concentrations of the target metal group (Ni, Zn, Cu, Cd, and Pb) by hydroxide precipitation, co-precipitation, and adsorption. Equilibrium speciation modeling showed that the HS-metal binding affinity controlled the effectiveness of HS addition for metal removal. The low HS complexation affinity of Ni and Zn resulted in no additional metal removal by HS dosing. The removal of Cu was enhanced by over 50% for SEHA 20 during-neutralisation conditions neutralised by both NaOH and Ca(OH)2. Up to 80% lower Cd concentrations were observed for all HS dose conditions when neutralised by Ca(OH)2. Data for CaCO3 HS dosed metal removal was statistically indeterminate. The high detection limit for Pb made any HS dosed removal enhancement difficult to identify, which was unfortunate as Pb has a high HS complexation affinity (Čežı́ková, Kozler et al. 2001; Milne, Kinniburgh et al. 2003). A simple cost: benefit analysis showed that the additional removal of metals by HS dosing was less efficient than conventional neutralisation alone, on a cost basis.
Overall, incorporation of HS into AMD treatment results in improved water quality for CaCO3 neutralisation and lower concentrations of metals with a high HS binding affinity, for some conditions. However, further investigation is required to improve the feasibility of HS incorporation into the AMD neutralisation process.
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Town, Raewyn. "Studies on the hydrophobic and hydrophilic properties of humic substances." Thesis, University of Canterbury. Chemistry, 1991. http://hdl.handle.net/10092/7834.
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This thesis presents a study on the solubility and aggregation properties of humic and fulvic acids, and their interaction with hydrophobic metal complexes and with aqueous metal ions. A parallel study involved quantitative analysis of solution equilibria between Al(III), Cu(II) and simple ligand systems representing possible complexing moieties in humic substances.
The solubility and aggregation properties of humic acid were studied as a function of pH and ionic strength by gel permeation chromatography and equilibrium dialysis. Predominantly smaller molecules were dissolved below pH 4; the solubility of the larger humic molecules increased with increased pH and with decreased ionic strength. The potential of XAD resins for the isolation of humic acid from soil extracts was investigated. These macroporous adsorbents were found to be unsuitable for this purpose. Large molecules were excluded from the XAD resins; those components which were adsorbed could not be completely desorbed by strongly alkaline solutions. In conjunction with the solubility studies these results highlighted the operational nature of the fraction defined as 'humic acid' and raised questions about the reported differences between aquatic and soil derived humic substances.
The interaction of humic substances with hydrophobic Cu(II) complexes (L = 1-(2-pyridylazo)-2-naphthol and 8-hydroxyquinoline) was studied by ASV (at a NCTMFE) and by visible absorption spectroscopy. Humic substances (HS) interacted hydrophilically with these species (if necessary displacing a low molecular weight ligand) to form a ternary complex, HS-Cu-L. Algal assays established that humic acid could thus ameliorate the extreme toxicity of hydrophobic Cu(II) complexes provided that the displaced ligand itself is not toxic.
The apparent lability of Cu(II) and Pb(II) complexes with humic and fulvic acids was studied by anodic stripping voltammetry (ASV). At a hanging mercury drop electrode (HMDE) the Cu(II) complexes of humic and fulvic acids were of similar lability; the apparent lability decreased as the pH increased. Complexes of humic substances with Cu(II) were less labile than those with Pb(II). Results were dependent on the electrode system used for the measurements. The effects of adsorption of humic substances on several electrode surfaces were characterized (HMDE, thin mercury film (TMFE), Nafion-coated TMFE, and bare glassy carbon). These effects were exerted predominantly in the deposition step. A method for measuring the apparent lability of metal-humic complexes was developed which corrected for the contribution from adsorption.
Ion selective electrode (ISE) potentiometry was used to probe the complexation capacity of humic and fulvic acids for Cu(II) (at pH 5.0, 6.3, and 7.0) and the relative stability of these complexes (pH 2.5 - 7.5). For both humic substances the complexation capacity increased with pH. Assuming bidentate coordination then, for fulvic acid at pH 5.0, 6.3, and 7.0 respectively, complexation capacity measurements indicated that 82- 85%, 67- 72%, and 50 - 60% of carboxyl groups were not involved in strong Cu(II) binding under the experimental conditions. For humic acid the proportions were 73 - 79%, 33 - 43% and 5 - 25% respectively. Cu(II) complexes with fulvic acid were significantly less stable than those with humic acid. At the same carboxyl group concentration, Cu(II) binding curves for humic acid were displaced markedly to lower pH, indicating stronger binding. For a 1:20 Cu(II):COOH ratio the pH displacement between the humic and fulvic acid curves was 0.65 at pH 3.5 and 1.0 at pH 5.0. The larger humic acid molecules (fractionated by 0.025 μm filtration in weakly acidic solution) were stronger complexors than were the smaller moieties. The apparent stability of Cu(II)-humic complexes decreased with increased metal-to-ligand ratio and with increased ionic strength. The competition of Mg(II) and Al(III) for humic Cu(II) complexation sites was studied. Simulation of the Cu(II) binding curves for humic substances identified the discrete ligands malonate and citrate as reasonable models for humic chelating sites; complexation by salicylate and phthalate moieties was considerably weaker than that by humic substances.
Quantitative pH potentiometric studies were made on the complexation of Cu(II) and Al(III) by carboxylate ligands (25°C, 0.1 mol L-1 KCl). The models which best described the solution equilibria in the Al(III) systems were:
Al(III)-malonic acid: AlL (log K = 6.71), AlL2 (4.94), AlL3 (2.61), AlL20H (-7.0)
Al(III)-isocitric acid: AlHL (10.07), AlL (6.96)
The Cu(II)-5-methoxy-N-(2-hydroxybenzyl)sarcosine system (CuL (7.05), CuLH.1 (-3.98)) demonstrated the contribution of 'cascade binding' to metal complex stability.
Formation of insoluble species in the Cu(II)-butane-1,2,3,4-tetracarboxylic acid system prevented quantitative analysis.
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O'Connor, Jane Mary. "Removal of naturally occurring colour and associated metals from upland waters by adsorption." Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252329.
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De, Nobili Maria. "An investigation of the relative importance of soil organic matter and fresh substrates for microbial survival in soil." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251940.
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Kay, Rajiv Robert. "Actinide partition in humic colloidal ternary systems." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/actinide-partition-in-humic-colloidal-ternary-systems(c21f9744-46fb-477f-9ebc-af87d3e6fca0).html.
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The partition of radionuclides between solid and solution phase has been studied in humic/quartz sand ternary systems. Data have been recorded under ambient (air) and inert (O2 and CO2 free) atmospheres. For Eu (III) and Th (IV), the systems show simple ternary behaviour, with sorption decreasing (and mobility increasing) in the presence of humic, whilst for U (VI), the behaviour is more complex, with the humic enhancing sorption and reducing mobility. There is also evidence that the sorbed humic has an enhanced affinity for the uranyl, which is probably due to fractionation of the humic. Further, the behaviour of plutonium has also been studied in these systems. Pu (IV) showed the simple ternary characteristics, which had been observed for Eu (III) and Th (IV). Pu (V) and Pu (VI) systems exhibited more complex behaviour, with low concentrations of humic actually enhancing sorption, probably due to ternary complex formation. A simple mathematical model has been developed to predict the behaviour of both metal ion and humic acid. The model performs well in predicting the partition of the humic and that of the metal ions in the systems that show simpler ternary behaviour.
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Olson, B. M. "Spectroscopic study of interactions between s-triazine herbicides and humic substances." Thesis, University of Aberdeen, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374630.
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Ho, Sharon 1975. "The effect of iron on the photo-oxidation of humic substances." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50367.
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Bartschat, Bettina Margrit. "An electrostatic model for the metal binding properties of humic substances." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13630.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1990.Title as it appears in the Sept. 1990 M.I.T. Graduate List: An electrostatic model for the metal-binding properties of humic substances.
Includes bibliographical references (leaves 35-37).
by Bettina Margrit Bartschat.
M.S.
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Francois, Adou Yedes Akpa. "Filtration removal of reverse micelle humic substances using a polypropylene medium." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150283.
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Jeong, Chang-Yoon. "Modelling metal competition for adsorption sites on humic acid." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389363.
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Voelker-Bartschat, Bettina Margrit Voelker-Bartschat Bettina Margrith. "Iron redox cycling in surface waters : effects of humic substances and light /." [S.l.] : [s.n.], 1994. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10901.
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Assemi, Shoeleh 1963. "Use of flow field-flow fractionation for the characterisation of humic substances." Monash University, Dept. of Chemistry, 2000. http://arrow.monash.edu.au/hdl/1959.1/9028.
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Jacinthe, Pierre-Andre. "Adsorption of the nitrification inhibitors nitrapyrin and dicyandiamide by soil humic substances." Virtual Press, 1990. http://liblink.bsu.edu/uhtbin/catkey/722445.
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Adsorption of the nitrification inhibitors dicyandiamide (DCD) and nitrapyrin (2-chloro-6(trichloromethyl)-pyridine) on humic acid (HA) and fulvic acid (FA) extracted from five Indiana soils was studied. Ten mg of HA or FA were suspended in aqueous solutions (10 ml) of either DCD (5,10, 20, 40 and 80 ug ml-1) or nitrapyrin (2,4,6,8,12 ug ml-1). The amount of nitrification inhibitor absorbed was evaluated after shaking the suspension of DCD for 48 h or nitrapyrin for 24 h. Infrared spectra of the nitrification inhibitor-humic material complexes were recorded. The results indicated that FA adsorbed more DCD than HA, and HA was a better adsorbent for nitrapyrin. Correlation between Freundlich K values and organic carbon content of HA and FA was not statistically significant, indicating a slight contribution of hydrophobic forces in the adsorption of DCD and nitrapyrin. The infrared spectra provided evidence that adsorption occurred predominantly through an ionic bonding mechanism involving the protonated amino group of DCD or the nitrogen of the pyridine ring of nitrapyrin and the negative functional groups of the humic materials.Department of Natural Resources
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Jones, Nastassia Nicole. "The analysis of humic substances as an electron donor for soil processes /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1400959831&sid=7&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Thesis (M.S.)--Southern Illinois University Carbondale, 2007."Department of Molecular Biology, Microbiology and Biochemistry." Includes bibliographical references (leaves 59-66). Also available online.
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Bell, Nicholle Georgina Anneke. "Molecular-scale characterisation of humic substances using isotope-filtered nD NMR spectroscopy." Thesis, University of Edinburgh, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.716584.
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Humic substances (HS), the complex mixture of organic molecules produced by microbial and abiotic degradation of plant and animals residues, are the major components of organic matter in soil and natural waters. As such, they are vital to the integrity of soil, play important roles in nutrient biogeochemical cycling and determine the mobility and fate of both nutrients and contaminants. How HS enact their varied roles, however, is largely unknown due to the lack of comprehension of their molecular make-up. What is known is that they contain aromatic (e.g. phenols, condensed aromatics) and aliphatic (e.g. carbohydrates, lipids) molecules with prevailing carboxyl and hydroxyl functionalities. As for other complex chromatographically inseparable mixtures, high-resolution analytical techniques such as Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) as well as Nuclear Magnetic Resonance (NMR) spectroscopy have been applied to study HS composition at the molecular level. While FT-ICR MS can provide molecular formulae, it is only NMR that can unveil structures. Until now, however, very few unambiguous structures of individual molecules have emerged from standard NMR experiments. This is because purposely designed multidimensional NMR experiments are required to achieve ‘spectroscopic separation’ where chromatography fails. In this work, ‘spectroscopic separation’ was accomplished with the aid of chemical modification in the form of 13C methylation of COOH and OH groups. 13C containing tags allow the observation of signals only from molecules carrying these tags. In combination with purposelydesigned isotope-filtered NMR experiments, these tags act as spies reporting on their surrounding structure. This is achieved by utilising scalar and dipolar couplings to transfer the polarisation between protons and carbons of the 13CH3O groups and nuclei of the parent molecules. The necessary spectral resolution is attained using 3D/4D NMR experiments. This approach provides access to an array of correlated chemical shifts of HS molecules and represents a paradigm shift in the use of tags in investigations of complex mixtures: instead of focusing only on the tags, they are used to obtain structural information from the molecules they are attached to. The compounds at the centre of this investigation are the phenols of HS. These molecules are thought to be important in many of the key processes in organic matter rich soils, particularly peat. For example, their accumulation is thought to impair the activity of extracellular enzymes essential for the degradation of peat HS. Understanding the nature and source of phenols would provide a more fundamental framework for rationalising their role in peat, as well as other carbon rich soils. The developed methodology was initially tested on model mixtures containing 3 or 9 phenolic compounds before applying it to a operational fraction of HS, fulvic acid, extracted from a Scottish raised peat bog. For this fulvic acid, over 30 major phenolic molecules/moieties were identified, many of which can be directly traced to the flora prevalent in the vicinity of the sampling site. For the first time in 150 years of HS research, a novel analytical methodology has yielded unambiguous structural information, providing the first steps towards understanding the various roles of HS in natural systems.
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Filipe, Olga Manuela Simão. "Thiram in the environment: effect of humic substances and Cu(II) ions." Doctoral thesis, Universidade de Aveiro, 2012. http://hdl.handle.net/10773/9891.
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Doutoramento em QuímicaEm Portugal, o tirame é um dos fungicidas mais utilizados, cujas vendas aumentaram significativamente nos últimos anos, sendo também um dos fungicidas mais utilizados em todo o mundo. No entanto, em comparação com outros pesticidas, existe falta de informação na literatura sobre o seu comportamento em sistemas ambientais, nomeadamente, no que diz respeito à sua degradação no solo ou em águas e produtos a que dá origem. Neste contexto, o objetivo deste trabalho foi estudar a influência das substâncias húmicas e iões cobre no comportamento e destino do tirame no meio ambiente. Foram realizados vários estudos para analisar o comportamento do tirame em solos com diferentes conteúdos de matéria orgânica e de iões cobre, e em águas naturais, estudando como as substâncias húmicas, os iões cobre e a luz solar podem afetar a sua degradação. Os estudos de adsorção-desadsorção do tirame nos solos revelaram que a matéria orgânica do solo e o conteúdo de cobre afetavam os processos de adsorção-desadsorção do tirame, influenciando a sua lixiviação e persistência no solo. De facto, verificou-se que o teor de cobre do solo tinha um efeito bastante marcante no processo de adsorçãodesadsorção do tirame. Verificou-se a ocorrência de reações entre o tirame e os iões cobre, cuja extensão durante os estudos de adsorção pode ser fortemente dependente do teor de cobre do solo e da concentração inicial de tirame em solução. Assim, a escolha do tempo de equilíbrio em estudos de adsorção e a determinação das isotérmicas de adsorção ao solo torna-se uma tarefa difícil. Além disso, os complexos formados com o cobre existente no solo são persistentes, não sendo facilmente lixiviados para as águas subterrâneas. Conclui-se que os iões cobre(II) podem contribuir para a imobilização do tirame no solo e o aumento da persistência dos seus resíduos ligados ao cobre. A partir de estudos de recuperação do tirame em águas naturais verificou-se a ocorrência de uma rápida degradação do tirame, devido provavelmente aos iões metálicos, nomeadamente, iões cobre. Verificou-se que dependendo da razão tirame:Cu podiam ocorrer dois processos: (i) complexação entre o tirame e o cobre, quando não há excesso de iões cobre, sendo o complexo formado mais persistente que o tirame; (ii) ou, quando há um grande excesso de iões cobre, a degradação do tirame e a estabilização dos produtos de degradação por complexação, podendo formar-se complexos que permanecem sem alteração em solução durante pelo menos dois meses. No geral, foi possível, pela primeira vez, identificar alguns dos complexos de cobre formados ao longo do tempo. Por fim, estudou-se a cinética de fotodegradação do tirame em solução aquosa sob a ação da luz solar e identificaram-se, pela primeira vez, três fotoprodutos. Verificou-se um aumento da velocidade de fotodegradação do tirame na presença de substâncias húmicas. Assim, podemos concluir que a matéria orgânica, os iões cobre(II) e a luz solar têm um efeito importante no comportamento do tirame no meio ambiente. Contudo, os iões cobre têm um efeito mais marcante na degradação e persistência dos produtos que são formados.
In Portugal thiram is one of the most used fungicides, whose sales have increased significantly along the years and it is also one of the most used fungicides all over the world. However, comparing to other pesticides, there is a lack of information in the literature about the behaviour of thiram in environmental systems, namely, in what concerns its degradation in soil or in water systems and products formed. In this context, the aim of this work was to assess the influence of humic substances and copper ions on the behaviour and fate of thiram in the environment. Different studies were performed to assess the behaviour of thiram in soils, with different organic amendments and with different copper contents, and in natural water, studding how humic substances, copper ions and sunlight can affect its degradation. Adsorption-desorption studies of thiram onto soil revealed that organic mater and soil copper contents affect thiram adsorption-desorption processes, influencing its leachability and persistence in soil. In fact, soil copper content has a marked effect on the sorption process of thiram onto soil. Reactions between thiram and copper ions occur and the extent of their occurrence during adsorption studies may be strongly dependent on the soil copper content and on the initial thiram concentration in solution making the choice of the equilibration time for batch sorption studies and adsorption isotherms determination a difficult task. The complexes formed with copper in soil are persistent, and they are not easily leached from soil to groundwater. Thus, we can conclude that copper may contribute to the immobilization of thiram in soil. Thiram recovery from natural waters showed rapid thiram degradation in environmental matrices, probably due to metal ions, namely copper. Depending on the Thi:Cu ratio two processes can occur: (i) when there is no excess of copper ions there will be the complexation between thiram and copper ions and the complex formed is more persistence than thiram; (ii) in the presence of a large excess of copper ions, which is the more probable situation in natural waters, thiram degradation can occur and then the degradation products are stabilized by complexation, forming complexes which can persist in aqueous solutions for at least two months. It was possible, by the first time, to identify some copper complexes formed. The kinetics of the photodegradation of thiram in aqueous solutions, under sunlight, was studied and three photodegradation products were identified for the first time. Besides, it was shown that humic substances enhance the thiram photodegradation rate. Thus, we can conclude from this work that the organic matter, copper ions and sunlight have important effects on the behaviour and fate of thiram in the environment. However it should be highlighted that copper ions have an extremely marked effect on the degradation of thiram and persistence of products which are formed.
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Patterson, Michael D. "Aspects of humic and fulvic acid chemistry." Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/22018.
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Humic and fulvic acids are present in all environmental waters and are known to combine with environmental contaminants and pollutants producing water soluble complexes. These complexes may be much more mobile than the unassociated contaminant through the environment because of groundwater and surface water movement. Therefore, of considerable interest, is to determine the characteristics and contaminant complexing ability of these materials. Most investigations of the complexing abilities of humics have been conducted on material which has been extracted from natural waters. The resulting solid humic material is then redissolved in an aqueous solution of known chemical composition. Part one of this thesis describes work designed to ascertain whether the extraction procedure alters the properties of the material, thus invalidating the results obtained from e.g. stability constant measurements. Experiments showed that the material was not altered and that measurements of stability constants using extracted material were valid. Part Two describes the development of an ion-exchange resin technique for measuring stability constants. Stability constants for the reaction of humic with nickel and europium were measured by this technique. The thesis also contains an account of the investigation and development of a method for investigating metal-humic interactions by fluorescence spectrophotometry. Competition reactions with calcium have also been investigated.
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Wold, Susanna. "On diffusion of organic colloids in compacted bentonite." Doctoral thesis, KTH, Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3522.
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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.
Keywords:Diffusion, sorption, complexation, stability,bentonite, humic substances, Sr(II), Co(II) and Eu(III).
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Smith, Esther Jane. "The biogeochemical behaviour of trace-metals in seasonally anoxic lake." Thesis, Lancaster University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266804.
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Toscano, Ilda Antonieta Salata [UNESP]. "Influência das substâncias húmicas aquáticas na determinação de atrazina por imunoensaio (Elisa)." Universidade Estadual Paulista (UNESP), 1999. http://hdl.handle.net/11449/105676.
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Made available in DSpace on 2014-06-11T19:35:05Z (GMT). No. of bitstreams: 0
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toscano_ias_dr_araiq.pdf: 387630 bytes, checksum: 64cc6245511279744bb2dd4a814e3afb (MD5)Substâncias húmicas aquáticas (SHA) foram obtidas por processo de adsorção em resinas macroporosas não-iônicas, XAD 7 e XAD 2, dispostas em série. Após eluição com solução de NaOH, o extrato alcalino de SHA foi acidificado a pH 1,0 para separação em ácidos húmico (AH) que precipita, e ácido fúlvico (AF) o qual permanece em solução. Para caracterização físicoquímica do material húmico (AH e AF), foram feitas análise elementar, determinação do teor de substâncias húmicas e acidez total. Os resultados obtidos por UV-VIS e FTIR indicaram que AH apresenta maior número de grupos aromáticos em relação a AF, que em geral possui mais cadeias alifáticas. A aplicação da técnica imunoquímica, enzyme-linked immunosorbent assay (ELISA), para a determinação do herbicida atrazina em águas foi avaliada em amostra de água contendo alto teor de matéria orgânica (~35 mg L-1) e baixo valor de pH (3,8). O efeito matriz devido a presença de SHA pode ser notado pela perda de sensibilidade da técnica, ou seja, os valores de IC50 variaram de 60 ng L-1, na ausência de SHA, para 112 ng L-1 em concentrações acima de 10,0 mg L-1 de material húmico e para 137 ng L-1 em pH < 5,0. Além disto, pode-se inferir que a luz solar aumentou a velocidade de degradação da atrazina na presença de SHA formando produtos, com partes de suas estruturas, semelhantes ao produto original levando a resultados falso-positivos. A quantidade de material húmico presente na amostra de água foi a principal fonte de erro na análise de atrazina, levando à interações não-específicas entre as SHA e os reagentes enzimáticos. O procedimento ELISA, aplicado neste estudo, pode ser utilizado para determinação de atrazina desde que se faça diluição da amostra até cerca de 2,5 mg L-1 de húmicos e em pH alcalino (7,0 – 9,0).
Aquatic humic substances (AHS) were isolated from water samples using Amberlite XAD 7 and XAD 2. After elution with NaOH solution, the XAD concentrated AHS was fractioned at pH 1.0 resulting in fulvic acid (FA - supernatant) and humic acid (HA - slurry). All humic materials were characterized with respect to elemental analysis, amount of AHS and total acidity. UV and FTIR spectra showed HA aromatic character greater than FA. Enzyme-linked immunosorbent assay (ELISA) was evaluated by analyzing atrazine in rich-humic matter water sample (~35 mg L-1) and acid water (pH 3.8). From all the conditions studied the low pH (pH < 5.0) and high humic substances concentrations (>10 mg L-1) showed the greatest influence. The IC50 values to control sample (no humic) decreased from 60 ng L-1 to 112 ng L-1 to humic solution at >10 mg L-1 and to 137 ng L-1 at pH < 5.0. The presence of AHS alters the photochemical behaviour of atrazine by accelerating its degradation forming metabolites which can be recognized by the antibodies. The assay performance showed a strong dependence on the pH values and amount of humic matter. However, analysis could be carried out directly in samples containing HA or FA that had been adjusted the pH in the range between 7.0 and 9.0, and humic concentration at 2.5 mg L-1.
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Collins, Michael Robin. "Removal of aquatic organic matter and humic substances by selected water treatment processes." Diss., The University of Arizona, 1985. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1985_382_sip1_w.pdf&type=application/pdf.
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Peters, Adam J. "A study of the binding of trace metals and radionuclides by humic substances." Thesis, Lancaster University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310586.
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Nitsche, Heino, Karl-Heinz Heise, Gert Bernhard, Katja Schmeide, Susanne Pompe, and Marianne Bubner. "Influence of Humic Acids on the Migration Behavior of Radioactive and Non-Radioactive Substances Under Conditions Close to Nature -Synthesis, Radiometric Determination of Functional Groups, Complexation-." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-30193.
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The interaction behavior of humic acids with uranium(VI) and the influence of humic substances on the migration behavior of uranium was investigated. A main focus of this work was the synthesis of four different humic acid model substances and their characterization and comparison to the natural humic acid from Aldrich. A radiometric method for the determination of humic acid functional groups was applied in addition to conventional methods for the determination of the functionality of humic acids. The humic acid model substances show functional and structural properties comparable to natural humic acids. Modified humic acids with blocked phenolic OH were synthesized to determine the influence of phenolic OH groups on the complexation behavior of humic acids. A synthesis method for 14C-labeled humic acids with high specific activity was developed. The complexation behavior of synthetic and natural humic acids with uranium(VI) was investigated by X-ray absorption spectroscopy, laser-induced fluorescence spectroscopy and FTIR spectroscopy. The synthetic model substances show an interaction behavior with uranium(VI) that is comparable to natural humic acids. This points to the fact that the synthetic humic acids simulate the functionality of their natural analogues very well. For the first time the influence of phenolic OH groups on the complexation behavior of humic acids was investigated by applying a modified humic acid with blocked phenolic OH groups. The formation of a uranyl hydroxy humate complex was identified by laserspectroscopic investigations of the complexation of Aldrich humic acid with uranium(VI)at pH 7. The migration behavior of uranium in a sandy aquifer system rich in humic substances was investigated in column experiments. A part of uranium migrates non-retarded through the sediment, bound to humic colloids. The uranium migration behavior is strongly influenced by the kinetically controlled interaction processes of uranium with the humic colloids. The influence of humic acids on the sorption of uranium(VI) onto phyllite was investigated in batch experiments using two different humic acids. The uranium(VI) sorption onto the rock phyllite is influenced by the pH-dependent sorption behavior of the humic acids.
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Nitsche, Heino, Karl-Heinz Heise, Gert Bernhard, Katja Schmeide, Susanne Pompe, and Marianne Bubner. "Influence of Humic Acids on the Migration Behavior of Radioactive and Non-Radioactive Substances Under Conditions Close to Nature -Synthesis, Radiometric Determination of Functional Groups, Complexation-: Influence of Humic Acids on the Migration Behavior of Radioactive and Non-Radioactive Substances Under Conditions Close to Nature -Synthesis, Radiometric Determination of Functional Groups, Complexation-." Forschungszentrum Rossendorf, 2000. https://hzdr.qucosa.de/id/qucosa%3A21846.
Full textAbstract:
The interaction behavior of humic acids with uranium(VI) and the influence of humic substances on the migration behavior of uranium was investigated. A main focus of this work was the synthesis of four different humic acid model substances and their characterization and comparison to the natural humic acid from Aldrich. A radiometric method for the determination of humic acid functional groups was applied in addition to conventional methods for the determination of the functionality of humic acids. The humic acid model substances show functional and structural properties comparable to natural humic acids. Modified humic acids with blocked phenolic OH were synthesized to determine the influence of phenolic OH groups on the complexation behavior of humic acids. A synthesis method for 14C-labeled humic acids with high specific activity was developed. The complexation behavior of synthetic and natural humic acids with uranium(VI) was investigated by X-ray absorption spectroscopy, laser-induced fluorescence spectroscopy and FTIR spectroscopy. The synthetic model substances show an interaction behavior with uranium(VI) that is comparable to natural humic acids. This points to the fact that the synthetic humic acids simulate the functionality of their natural analogues very well. For the first time the influence of phenolic OH groups on the complexation behavior of humic acids was investigated by applying a modified humic acid with blocked phenolic OH groups. The formation of a uranyl hydroxy humate complex was identified by laserspectroscopic investigations of the complexation of Aldrich humic acid with uranium(VI)at pH 7. The migration behavior of uranium in a sandy aquifer system rich in humic substances was investigated in column experiments. A part of uranium migrates non-retarded through the sediment, bound to humic colloids. The uranium migration behavior is strongly influenced by the kinetically controlled interaction processes of uranium with the humic colloids. The influence of humic acids on the sorption of uranium(VI) onto phyllite was investigated in batch experiments using two different humic acids. The uranium(VI) sorption onto the rock phyllite is influenced by the pH-dependent sorption behavior of the humic acids.
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Mariner, Paul Edwin 1964. "The effects of humic substances on the transport of copper(II) in ground water." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/292020.
Full textAbstract:
To improve the understanding of the movement of copper plumes in natural ground water systems, the partitioning and transport of Cu(II) in the presence of natural humic substances were investigated in the lab. The humic substances were isolated from high organic content ground water in Orange County, CA (5mgCL⁻¹). Batch and titration experiments produced one-site Langmuir isotherms for the sorption of Cu(II) (0.1-5.0 mgL⁻¹) to am-SiO₂ (K(L) = 1.46Lmg-1, Q = 5.92μgg⁻¹), α-Al₂O₃ (K(L) = 100L mg⁻¹,Q = 130μgg⁻¹), and aqueous humics (pK₁ = -5.5, pL₁ = 5.1). Results of the column experiments suggest that mobile humics facilitate the transport of Cu(II) by lowering the free Cu(II) concentration. Mineral-bound humics retarded the transport of Cu(II) by increasing the concentration of immobile binding sites and by binding considerably more Cu(II) per mass carbon than aqueous humics. The measured Langmuir isotherms accurately predicted retention times and explained much of the tailing of the desorption breakthrough curves.
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Liu, X. "Removal of humic substances from water using solar irradiation and granular activated carbon adsorption." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/20232/.
Full textAbstract:
For the existing water treatment processes, difficulties in removing humic substances (HS) to improve drinking water quality, and safety, have created the demand for exploring novel options to enhance HS removal. Here a combination of solar irradiation and granular activated carbon (GAC) adsorption is proposed. It aims to make use of the most freely available and abundant energy source, sunlight, to improve the performance of GAC adsorption process. An investigation into how characteristics of HS vary under natural sunlight and how this influences the subsequent removal of HS by GAC adsorption was carried out. Bulk water parameters, and more specifically, UV absorbance at 254 nm (UV254), as well as dissolved organic carbon (DOC) were used in conjunction with molecular weight (MW) to evaluate the performance of the solar-GAC method. The observation was made that solar irradiation led to a decrease in DOC, UV254 and MW of HS. The high MW components were photodegraded into smaller molecules, even with very low solar intensity in winter. Significant photodegradation of small molecules was also achievable by exposure to natural sunlight alone. Pre-treatment using solar irradiation was shown to successfully improve the GAC adsorption performance on HS removal, increasing the DOC removal from 69 % to 95 %. An up to three-fold increase in the adsorption capacity of GAC for the irradiated HS was observed. Solar collectors were found to effectively enhance the photodegradation of HS, and consequently enhance the removal of HS by GAC adsorption. The application of solar collectors could be a viable option for humic water treatment. The proposed solar irradiation-GAC adsorption method provides a new approach for the treatment of humic rich waters. The utilization of solar irradiation in water treatment processes is considered a sustainable and promising field.
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Watanabe, Cláudia Hitomi. "Fate, behavior and ecotoxicology of silver nanoparticles : interactions with natural organic matter in aquatic systems /." Sorocaba, 2020. http://hdl.handle.net/11449/192324.
Full textAbstract:
Orientador: André Henrique RosaResumo: When introduced in environment, manufactured nanoparticles (NPs) can interact with biotic and abiotic molecules yielding a transformed NP usually coated with these molecules (natural coating). These different forms of the NPs should be considered as new materials because them distinct properties from the released NPs forms. In fact, these in situ transformations of the NPs have relevant impacts on their toxicological effects, having new or additional risks still not studied. This project aims to determine, understand and predict the impact of natural molecules in the transformations and bio-effects of Ag NPs, widely used as antibacterial agents. Despite the growing interest and use of these NPs, the gathered knowledge on their environmental consequences is still scarce, since the large majority of the studies do not consider the effect of the presence of natural coatings around the particles. In fact, most of the studies do not even determine the effects of the presence of manufactured coatings. Generally, NPs manufacturers add ionic or polymeric coatings to improve their mobility and stabilization in terms of size. Although the possible effects of these manufactured coatings in the NPs behavior there is not systematically studied about their impact. This project aims to overcome the current uncertainty about the environmental safety of manufactured coated NPs, and explore the impact of natural molecules on their environmental risk. The project objectives are: i) characterize... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor
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Geipel, Gerhard, Susanne Sachs, Vinzenz Brendler, Jens Mibus, Adela Krepelova, Alix Günther, Katja Schmeide, Astrid Koban, and Gert Bernhard. "Joint Project: Migration of Actinides in the System Clay, Humic Substance, Aquifer - Migration Behavior of Actinides (Uranium, Neptunium) in Clays: Characterization and Quantification of the Influence of Humic Substances (Final Report BMWi Project No.: 02 E 9673)." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-28318.
Full textAbstract:
Objective of this project was the study of interaction processes between humic substances, U(VI), Np(V) and kaolinite KGa-1b. It contributed to the attainment of a better process understanding, the improvement of the knowledge on the interaction of humic substances and metal ions and the enhancement of the thermodynamic database. With a synthetic humic acid (HA), N-containing functional groups of HA were characterized by 15N-NMR spectroscopy. Based on these results, model studies of the influence of amino groups on the complexation behavior of HA were performed. Spectroscopic studies with amino acids show that the amino group do not contribute to the U(VI) complexation at pH 4. The impact of kaolinite on the formation of HA and humic substance-kaolinite-sorbates was studied in model syntheses. The results exhibit that the presence of kaolinite during the syntheses mainly influences the yields on HA and their elemental compositions. Synthetic humic substance-kaolinite-sorbates were isolated. Under exclusion of CO2, the U(VI) complexation by HA was investigated at pH 7 by means of the conventional time-resolved laser-induced fluorescence spectroscopy (TRLFS) and TRLFS with ultrafast pulses. Complexation parameters for the ternary complex UO2(OH)HA(I) were determined. Studies of the Np(V) reduction in presence of HA with different functionalities under anaerobic conditions have shown that Np(V) is reduced to Np(IV) by HA. The redox capacity depends on the HA functionality. Applying a modified HA it was verified that phenolic/acidic OH groups play a dominating role in the Np(V) reduction. The influence of HA on the U(VI) and Np(V) sorption onto kaolinite was investigated in batch experiments. In dependence on the experimental conditions, HA effects the sorption and consequently the mobility of U(VI) and Np(V). From studies of the U(VI) sorption onto synthetic humic substance-kaolinite-sorbates it was concluded that the structure and functionality of sorbed/associated humic substances considerably influence the sorption behavior of U(VI). The structure of U(VI)-kaolinite-surface complexes in presence of HA was studied by means of X-ray absorption spectroscopy and TRLFS and compared to those of U(VI)-kaolinite-complexes. Investigations of the migration of HA and U(VI) in the laboratory system kaolinite-water were carried out in diffusion experiments. The migration of HA in compacted clay is governed by diffusion and influenced by its colloidal properties. Humic substances exert an immobilizing effect on the U(VI) transport in compacted kaolinite.
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Geipel, Gerhard, Susanne Sachs, Vinzenz Brendler, Jens Mibus, Adela Krepelova, Alix Günther, Katja Schmeide, Astrid Koban, and Gert Bernhard. "Joint Project: Migration of Actinides in the System Clay, Humic Substance, Aquifer - Migration Behavior of Actinides (Uranium, Neptunium) in Clays: Characterization and Quantification of the Influence of Humic Substances (Final Report BMWi Project No.: 02 E 9673)." Forschungszentrum Dresden-Rossendorf, 2007. https://hzdr.qucosa.de/id/qucosa%3A21658.
Full textAbstract:
Objective of this project was the study of interaction processes between humic substances, U(VI), Np(V) and kaolinite KGa-1b. It contributed to the attainment of a better process understanding, the improvement of the knowledge on the interaction of humic substances and metal ions and the enhancement of the thermodynamic database. With a synthetic humic acid (HA), N-containing functional groups of HA were characterized by 15N-NMR spectroscopy. Based on these results, model studies of the influence of amino groups on the complexation behavior of HA were performed. Spectroscopic studies with amino acids show that the amino group do not contribute to the U(VI) complexation at pH 4. The impact of kaolinite on the formation of HA and humic substance-kaolinite-sorbates was studied in model syntheses. The results exhibit that the presence of kaolinite during the syntheses mainly influences the yields on HA and their elemental compositions. Synthetic humic substance-kaolinite-sorbates were isolated. Under exclusion of CO2, the U(VI) complexation by HA was investigated at pH 7 by means of the conventional time-resolved laser-induced fluorescence spectroscopy (TRLFS) and TRLFS with ultrafast pulses. Complexation parameters for the ternary complex UO2(OH)HA(I) were determined. Studies of the Np(V) reduction in presence of HA with different functionalities under anaerobic conditions have shown that Np(V) is reduced to Np(IV) by HA. The redox capacity depends on the HA functionality. Applying a modified HA it was verified that phenolic/acidic OH groups play a dominating role in the Np(V) reduction. The influence of HA on the U(VI) and Np(V) sorption onto kaolinite was investigated in batch experiments. In dependence on the experimental conditions, HA effects the sorption and consequently the mobility of U(VI) and Np(V). From studies of the U(VI) sorption onto synthetic humic substance-kaolinite-sorbates it was concluded that the structure and functionality of sorbed/associated humic substances considerably influence the sorption behavior of U(VI). The structure of U(VI)-kaolinite-surface complexes in presence of HA was studied by means of X-ray absorption spectroscopy and TRLFS and compared to those of U(VI)-kaolinite-complexes. Investigations of the migration of HA and U(VI) in the laboratory system kaolinite-water were carried out in diffusion experiments. The migration of HA in compacted clay is governed by diffusion and influenced by its colloidal properties. Humic substances exert an immobilizing effect on the U(VI) transport in compacted kaolinite.