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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

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)

Geipel, Gerhard, Sachs, Susanne, Brendler, Vinzenz, Mibus, Jens, Krepelova, Adela, Günther, Alix, Schmeide, Katja, Koban, Astrid, Bernhard, Gert 31 March 2010 (has links) (PDF)
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.
92

Prophylaktischer und therapeutischer Einsatz von Braunkohle-Huminstoffen in der Nutz- und Zierfischzucht

Heidrich, Stefan 04 August 2005 (has links) (PDF)
F�r die Therapie und Prophylaxe von Fischkrankheiten stehen nur wenige geeignete und zugelassene Medikamente zur Verf�gung. Daher kommt der Suche nach wirksamen und f�r Tier, Verbraucher und Umwelt sicheren Alternativen in der Fischhaltung eine besondere Bedeutung zu. �ber positive Effekte beim oralen Einsatz von Huminstoffen an landwirtschaftlichen Nutztieren, Zootieren und Heimtieren liegen eine Vielzahl von Berichten vor. Deshalb sollten in der vorliegenden Studie Huminstoffe (HS) in der �u�erlichen Anwendung bei Zierfischen und in der oralen Verabreichung �ber das Futter bei Nutzfischen n�her untersucht werden. Dazu wurden zwei Versuche (B I: Dauer 4 Tage; B II: Dauer 12 Tage) an Goldfischen (Carassius auratus) unter teichwirtschaftlichen Bedingungen, zwei Aufzuchtversuche (F I: Kv bis K3, Dauer: 1.000 Tage: F II: K0 bis K1, Dauer: 150 Tage) an Karpfen (Cyprinus carpio) in der Teichwirtschaft und ein Aufzuchtversuch (F III: vorgestreckte Brut bis 30 g Lebendmasse, 166 Tage) an Regenbogenforellen (Oncorhynchus mykiss) unter Laborbedingungen durchgef�hrt. Als Versuchsparameter dienten Mortalit�t und Morbidit�t, Wachstum und Futteraufwand in den Aufzuchtversuchen, pathologisch anatomische (einschlie�lich histologischer Befunde in B I und F II), parasitologische, bakteriologische und virologische Kriterien. Die Wasserqualit�t wurde regelm��ig ermittelt. In den Versuchen B I und B II wurde eine 10%ige Na-Humat-L�sung (HS vom Typ WH 67 SNa der Fa. Pharmawerk Weinb�hla) dem H�lterungswasser so zugesetzt, dass eine Na-Humat-Konzentration von 10 mg L-1 entstand. Zweij�hrige, multifaktoriell erkrankte Goldfische (B I: N=2 x 322, B II: N=2 x 100) wurden dem Na-Humat-Bad t�glich f�r die Dauer einer Stunde (B I) bzw. von 1,5 bis 2 Stunden (B II) ausgesetzt. Die HS-Badehandlungen f�hrten in beiden Versuchen zu einer Senkung der Verluste (Mortalit�tsrate in B I: 0,6 versus 4,7 %, p<0,0005; B II: 8 versus 16 %, p<0,05). Bei Versuchsende war in den Versuchsgruppen (Na-Humat-Bad) der Gesundheitszustand, beurteilt nach �u�erlich sichtbaren Ver�nderungen an Haut, Flossen und Kiemen, deutlich verbessert (B I: p<1�10-16; B II: p<0,001). So waren (Signifikanzangaben nur f�r B II) vor allem H�morrhagien der Haut und der Flossen (p<0,05), Flossenrand- und Kiemennekrosen (p<0,05) sowie akute Kiemenentz�ndungen (p<0,02) verringert. Die Badebehandlungen bewirkten weiter eine geringere Auspr�gung integument�rer Mykosen der Haut, Flossen und Kiemen durch Pilze der Gattung Saprolegnia (p<0,05). Der Befall von Haut und Kiemen mit vorrangig protozo�ren Ektoparasiten konnte insgesamt ebenso vermindert werden (p<0,01) wie der Befall der Kiemen mit Ichthyophthirius sp. (p<0,05). Aus der beobachteten Milderung von Krankheitssymptomen umweltbedingter, bakterieller, ektoparasit�rer und mykotischer Genese nach Na-Humat-B�dern bei Goldfischen kann auf einen gewebeprotektiven, antiphlogistischen, antimykotischen und antiparasit�ren Effekt der Na-Humat-Behandlung geschlossen werden. In der Aufzucht von Karpfen (F I) und Regenbogenforellen (F III) wurden dem Futter 5 % Humocarb, formuliert� (HS vom Typ WH 67 A), im Karpfenversuch F II 5 % Cellu-Ligno-Karbon-Isolat (HS vom Typ WH 67 G, beide Produkte: Fa. Pharmawerk Weinb�hla) zugesetzt. In F I und F III wurde ein gleiches pelletiertes Alleinfutter f�r Forellen, in F II ein pelletiertes Alleinfutter f�r Karpfen eingesetzt. In Versuch F I (Besatzdichte der beiden Teiche (0,2 ha) jeweils 35.000 Kv ha-1) wiesen die Karpfen der Versuchs- gegen�ber der Kontrollgruppe h�here mittlere K�rpermassen auf. Der Unterschied zwischen den Gruppen bewegte sich mit einer Ausnahme (zu geringer Stichprobenumfang) zwischen p<0,05 (65 versus 45 g, 114. Tag) und p<0,0001 (1.146 versus 855 g, Versuchsende 1000. Tag). Der um die HS-Aufnahme bereinigte Futteraufwand des ersten Versuchsjahres war durch HS um 34 % verbessert. Die Futterquotienten in der zweiten und dritten Aufzuchtperiode waren durch die subjektive Futterzumessung (Nichtber�cksichtigung zwischenzeitlicher Verluste) verf�lscht. In Versuch F II (Besatzdichten der 2 x 3 Teiche (0,25 ha) 20.000, 30.000 bzw. 40.000 K0 ha-1) erhielten die Br�tlinge �ber die ersten zwei Wochen kein zus�tzliches Futter (nur Naturnahrung), anschlie�end wurde Weizenschrot zugef�ttert, erst ab dem 63. Tag das Versuchs- bzw. Kontrollfutter f�r 87 Tage. Bei Versuchsende war in den Gruppen der h�chsten Besatzdichte die Mortalit�t durch HS um ca. 20 % verringert (p<0,0001). Die Abfischungsmassen waren bei geringer Besatzdichte ann�hernd gleich, bei mittlerer Besatzdichte war die Kontrollgruppe, bei h�chster Besatzdichte die Versuchsgruppe favorisiert (statistische Pr�fung wegen des Fehlens von Einzeldaten nicht m�glich). Der um die HS-Aufnahme bereinigte Futteraufwand war in den HS-Gruppen bei geringer bzw. h�chster Besatzdichte um 5 bzw. 17 % verringert. In beiden Versuchen, F I und F II, wurde eine deutliche Verringerung des Gehaltes der inneren Organe Leber, Niere und Milz an fakultativ pathogenen Aeromonas- und Pseudomonas spp. nachgewiesen (p<0,05). Bei der Aufzucht von Regenbogenforellen (F III; N=2 x 25) trugen die durch den HS-Zusatz bedingten Ver�nderungen der Konsistenz von Futter und Kot zur Verminderung einer starken Belagbildung (Bewuchs aus Algen und anderen Mikroorganismen) sowie zur Vermeidung von Wassertr�bungen in den Aquarien, insbesondere bei h�heren Temperaturen, bei. Signifikante Unterschiede in den Kenndaten von Wachstum und Futteraufwand wurden nicht beobachtet. Insgesamt gesehen erscheint aber der Zusatz von 5 % HS zum Futter als zu hoch gew�hlt, da sich der Futteraufwand in den HS-Gruppen bei Ber�cksichtigung der Gesamtfuttermenge (einschlie�lich des 5%igen HS-Zusatzes) �berwiegend ung�nstiger gestaltete. Die Effekte der oralen Applikation von 5 % HS im Futter sind damit weit weniger augenf�llig als nach �u�erlicher Anwendung. Die zootechnischen Parameter waren �berwiegend mehr oder weniger unver�ndert; allein in Versuch F I war die K�rpermasse in der HS-Gruppen im Versuchsverlauf (Stichproben und Abfischung) in der Regel signifikant h�her als in der Kontrollgruppe. Von k�nftiger Bedeutung f�r die Aquarienhaltung von Fischen (und m�glicherweise in Klein- und Zierteichen) k�nnte die beobachtete Wasserkl�rung und die Verminderung einer Belagbildung aus Algen und anderen Mikroorganismen sein. Eine intestinale Wirkung der HS wird insoweit unterstellt, als in beiden Karpfenversuchen die inneren Organe einen verminderten Befall an beweglichen Aeromonaden und Pseudomonaden aufwiesen. / Prophylactic and therapeutic use of brown coal-derived humic substances of the type WH 67 in finfish and ornamental fish farming On the market, there is a limited number of suitable and approved drugs available for therapy and prophylaxis of fish diseases. The search for alternatives which are both effective and safe for animals, consumers and environment is therefore of special importance. There are numerous reports on positive effects of orally administered humic substances (HS) on agricultural livestock, zoo animals and pets. Therefore, the present study aimed on effects of HS for both external treatment of ornamental fish and oral application on culture fish via feed. Two experiments on goldfish (Carassius auratus) (exp. B I: 4 days; exp. B II: 12 days), and on common carp (Cyprinus carpio) (exp. F I: 1,000 days, fry to 3-year-old fish ; exp. F II: 150 days, fry to young-of-the-year size) were carried out under pond culture conditions. Additionally, one experiment on rainbow trout (Oncorhynchus mykiss) was carried out in the laboratory (exp. F III: 166 days, fingerlings up to 30 g body weight). The following parameters were examined: mortality, morbidity, growth, feed conversion ratio (exp. F I, F II, F III only), pathologic anatomical criteria (including histological examination of fish from B I and F II), parasitological investigation, bacteriological and virological state. Water quality was regularly examined as well. In the experiments B I and B II, a 10% sodium-humate solution (type WH 67 SNa, Pharmawerk Weinb�hla) was mixed into the water until a sodium-humate concentration of 10 mg L-1 was reached. Two-year old, multifactorially diseased goldfish (B I: N= 2 x 322; B II: N= 2 x 100) were daily exposed to this water for a period of one (B I) and 1.5-2 (B II) hours, respectively. In both experiments the treatment of fish reduced in mortality (B I: 0.6 vs. 4.7 %, p<0.0005; B II: 8 vs. 16 %, p<0.05). Moreover, at the end of the experiments the sodium-humate treated fish showed a significantly improved health state (B I: p<10-16; B II: p<0.001) as indicated by externally visible changes of the skin, fins and gills. Specifically, reductions in haemorrhage of skin and fins (B II: p <0.05), and fin and gill necroses (B II: p<0.05), and gill inflammations (B II: p<0.02) were noted. Additionally, the sodium-humate treatment reduced integumental mucoses of skin, fins and gills (p<0.05) caused by Saprolegnia sp. The infection of skin and gills with protozoan parasites was reduced (p<0.01) as well. Ichthyophthirius sp. infections of the gills dropped significantly (p<0.05) in the treated fish groups as compared to the controls. Due to the observed mitigation of disease symptoms of environmental, bacterial, parasitic and fungal origin after a sodium-humate bath treatment of goldfish, a tissue protective, antiphlogistic, antimycotic and antiparasitic effect of sodium-humate can be concluded. For rearing of carp (F I) and rainbow trout (F III), 5 % Humocarb, formuliert� (type WH 67 A, Pharmawerk Weinb�hla) was mixed among the feed, while for the experiment F II 5 % Cellu-Ligno-Carbon-Isolat (type WH 67 G, Pharmawerk Weinb�hla) was added. In F I and F III a complete feed for trout was applied whereas for F II a complete feed for carp was used. In experiment F I (stocking density of both ponds 35,000 carp fry per ha) test fish revealed a higher mean body weight compared to the controls. With one exception (sample size to small), the difference between the groups was either significant (day 114: 65 vs. 45 g, p<0.05) or highly significant (day 1000: 1,146 versus 855 g, p<0.0001). The feed conversion ratio of the first experimental year (expurgated by HS-uptake) improved by 34 % due to HS application. Feed conversion ratio of the second and third year were falsified because of subjective feeding (which does not consider occurring losses). In experiment F II (stocking density of the 2 x 3 ponds (0,25 ha) were 20,000, 30,000 and 40,000 individuals per ha, respectively) no additional feed was given to the hatched fry during the first two weeks so that all the fish lived on natural feed items. Afterwards, bruised wheat grain was given until from day 63 either test or control feed was applied for a total of 87 days. At the end of the experiment, at the highest stocking density the mortality was significantly (p<0.0001) decreased by 20% in the test group supplied with HS. At low stocking density the total weight of fish at harvest was not different between the test and control group. However, at medium stocking density the average body weight was higher in the control whereas reverse conditions were observed at the highest stocking density (due to a loss of data no statistical analysis was possible). The feed conversion ratio (expurgated by the uptake of humic substances) was decreased in the test groups of low (5 %) and high (17 %) density. In both experiments (F I and F II) significantly reduced infections of the internal organs liver, kidney and spleen with potentially pathogenic Aeromonas and Pseudomonas spp. were detected. In the rainbow trout rearing (F III; N = 2 x 25), the HS-caused changes in consistency of feed and faeces impaired the formation of heavy algal films and large microorganism populations, and contributed to less turbid water turbidity in the aquaria, particularly at high temperatures. Significant differences in growth and feed conversion ratio could not be observed. In general, the addition of 5 % HS to the feed is regarded as being too high because the total amount of feed given (inclusive 5 % HS) is considered. The feed conversion ratio was higher in most of the HS-groups. Effects of oral application of 5 % HS in feed were thus less obvious than the bath treatment. Zootechnical parameters, in general, did not change. Merely in experiment F I the body weight of the HS-groups was significantly higher than that of the controls. In aquaria and small ponds used for ornamental fish breeding the observed cleaning of water and reduced formation of algal films and microorganism populations caused by HS could be of future importance. Intestinal effects of HS are assumed as internal organs revealed a reduced infection with both motile aeromonads and pseudomonads.
93

A study of the kinetic interactions of complex metal ion : humic and magnetite ternary systems

Li, Nigel January 2012 (has links)
The sorption of humic acid (HA) and HA size fractions onto magnetite has been studied. There is considerable irreversibility in the interaction of the humic with the magnetite surface, but the presence of Eu3+ ions has no effect on the sorption of humic onto magnetite. The magnitude of the sorption to magnetite increases with HA fraction size for all ionic strengths between 0.01 and 3 mol dm-3. Increasing ionic strength also increases sorption. Asymmetric Flow Field Flow Fractionation analysis of HA sorption to magnetite after 1 day revealed preferential sorption of lower molecular weight material. Eu3+ sorption onto magnetite was studied as a function of Eu concentration, which showed an increase in relative sorption as Eu concentration decreased. The behaviour of Eu3+ in ternary (HA/Eu3+/magnetite) systems is heavily influenced by HA, and from the data there is direct evidence for ternary complex formation. Larger HA size fractions retain more Eu3+ in solution than the smaller fractions. The binding strengths of HA size fractions were determined through ion exchange resin experiments: generally the larger fractions (> 10 kDa) showed stronger binding than the smaller components, but the unfractionated sample showed the strongest binding.First order dissociation rate constants have been determined for the whole HA and HA size fractions. The dissociation rate constants are independent of HA fraction size, but the larger species bind more Eu non-exchangeably. Time series ultrafiltration of Eu3+/whole humic mixtures has shown a shift in the distribution of metal ions to larger size fractions after a few days. Two ternary system kinetic speciation models have been developed to predict the behaviour of HA and Eu3+ in ternary systems. The two differ in their description of the multi-component behaviour of the binary HA-mineral interaction. The first assumes a single HA species and two surface binding sites and was found to perform better overall than the second, which has a single surface sorption site and two HA species in solution. The exchangeable binding strengths for the different HA samples calculated from both models showed similarities to those measured experimentally.
94

Interakce ibuprofenu s huminovými látkami a stabilita vzniklých komplexů / Interaction of Ibuprofen with Humic Substances and Stability of Formed Complexes

Vlašicová, Silvie January 2021 (has links)
Nowadays, huge amounts of drugs get into watercourses and soil due to wrong disposal in sewage treatment plants. In this work, the sorption and desorption behavior of Ibuprofen in the soil system was studied, especially in relation to humic acids. The degree of sorption and desorption was defined from the change in ibuprofen concentration analyzed by UV-VIS spectrometry, changes in conductivity and pH were also observed. Ibuprofen shows good sorption properties, desorption was really minimal. It can be assumed that there is a strong bond between ibuprofen and both soil and lignite humic acids and therefore there is no risk of leaching back into solutions. Therefore, if ibuprofen entered the environment, it would be sorbed into the humic acids contained in lignite or soil, which means that it should not be harmful in any way.
95

Produkce a charakterizace regenerovaných huminových kyselin / Production and characterization of regenerated humic acids

Uhrová, Anna January 2008 (has links)
Jihomoravský lignit pocházející z dolu Mír v Mikulčicích, Lignit s.r.o. byl přesítován a vybraná frakce byla modifikována tzv. mokrou cestou pomocí dvou oxidačních (HNO3, H2O2) a dvou „amfifilních“ (kyselina octová, kyselina citronová) činidel. Alkalickou extrakcí byly získány jak huminové kyseliny z neupraveného tak předupraveného lignitu (tzv. regenerované huminové kyseliny). Na základě výsledku elementární analýzy byly vypočítány C/O a C/H poměry, které společně s FTIR spektry podaly informaci o stupni alifaticity/aromaticity a dále o stupni oxidace organického uhlíku. Pomocí vysokoúčinné vylučovací chromatografie byla stanovena distribuce velikosti huminových agregátů. K objasnění procesů probíhajících v povrchové vrstvě bylo proměřeno povrchové napětí studovaných roztoků vzorků. Získaná data byla proložena Szyszkowského rovnicí a obdržené parametry poukázaly jak na povrchovou aktivitu jednotlivých huminových kyselin tak i na povahu molekul zodpovědných za snižování povrchového napětí. Pro vzájemnou korelaci dat získaných výše zmíněnými metodami byl použit Pearsonův korelační koeficient.
96

Fluorescence půdních a lignitických huminových látek / Fluorescence of soil and lignite humic substances

Konečná, Soňa January 2009 (has links)
The purpose the diploma thesis was to determine main fluorophores of soil and lignite humic substances using methods of 2D synchronous fluorescence spectroscopy (SFS) and 3D SFS. These fluorescence methods are frequently used for characterization multifluorophore systems. Measured synchronous spectra were compared with standards IHSS. Next to that the aim was to find differences between chosen samples of humic and fulvic acids.
97

Kalorimetrická studie interakcí huminových látek s kovovými ionty / Calorimetric study of interactions of humic substances with metal ions

Solná, Irena January 2013 (has links)
The main object of the diploma thesis is study of interaction beetween humic acids and selected metal ions using calorimetric titration. The research about reactivity of humic substances is done comparing the different models used to describe the variety of properties of humic substances. In experimental part the methods of FT-IR spektrometry, potenciometric and conductometric titration are used to recieve the total acidity and carboxylic acidity of lignite humic acid. The optimalization of isothermic titration calorimetry is done to be used within study of reactivity of humic acids, revealing the best correlation with sols of studied humic acid. The basic organic compounds were used including benzoic acid, ftalic acid, salycilic acid, pyrocatechol and phenol as models of bonding groups in humic acids. The reaction enthalpy was calculated from the titration of models and results were compared with semiempiric quantum chemistry calculations following INDO method.
98

Interakce huminových hydrogelů s měďnatými ionty / Interactions of humic hydrogels with cupric ions

Lang, David January 2014 (has links)
This diploma thesis deals with humic acid gels and their ability to bind metallic ions on their surface. In the thesis, there was studied the adsorption of copper ions on the provided gels. The gels were prepared by dissolving the humic acid in sodium hydroxide or sodium tripolyphosphate and then precipitated with hydrochloric acid or metal chlorides. Adsorption was studied at different concentrations of the copper (II) chloride and measured on UV-VIS spectrophotometer. It was proved from measuring that gels made from sodium tripolyphosphate are adsorbing less copper ions than the ones prepared by sodium hydroxide. Also, the copper ions are bound with smaller force on gels prepared with polyphosphate. Gels precipitated with magnesium chloride adsorb much more than gels precipitated with acid, thus in the case of gels sequestered metal ions extracted higher.
99

Transport kovových iontů v huminových hydrogelech / Transport of metal ions in humic hydrogels

Hegr, Martin January 2017 (has links)
This diploma thesis is focused on the study of diffusion of metal ions in hydrogel of humic acid. The objective of this thesis was to investigate the effect of the concentration of metal ions supply source and duration of diffusion on transport through the gel using method of diffusion couple. Cupric, nickel and cobalt ions were esed like the diffusion medium. All these ions were selected thanks to their high affinity for the humic acids and because they are ideal to investigate the diffusion through the humic gel. Chloride salts of these metals, namely CuCl2, NiCl2 and CoCl2, were used like supply sources. Three different concentrations of each solution were compared, specifically 0,05M, 0,1M and 1M, and also were three different durations of diffusion, specifically 10 hours, 1 day and 3 days. Metal ions were compared with each other in order to determine which one has the best transport properties through the humic hydrogel. The data, necessary for calculation, were obtained by UV-VIS spectrophotometry. Diffusion coefficients and duffusive flux of individual metal ions were determined from measured data.
100

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)

Geipel, Gerhard, Sachs, Susanne, Brendler, Vinzenz, Mibus, Jens, Krepelova, Adela, Günther, Alix, Schmeide, Katja, Koban, Astrid, Bernhard, Gert January 2007 (has links)
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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