Diese Arbeit leistet einen methodischen Beitrag zur Identifizierung von Umsetzungsprozessen der Stickstoffverbindungen Ammonium und Nitrat in belasteten Grundwasserleitern mittels der Analytik der Isotopenverhältnisse N-15 bzw. O-18. Es existieren bereits verschiedene Präparationsmethoden, jedoch sind diese teilweise arbeits- oder zeitaufwändig und damit mit erheblichen Kosten verbunden. Für eine breitere Anwendbarkeit in den Umweltwissenschaften wurden im Rahmen dieser Arbeit zwei vereinfachte Methoden für die N-15 bzw. O-18 Stabilisotopenanalytik von Ammonium und Nitrat in Wässern erarbeitet. Zum einen wurde eine Fällungsmethode mit Natriumtetraphenylborat für die Probenvorbereitung der N-15 Isotopenanalyse für Ammonium weiterentwickelt, getestet und validiert. Bisher existierten keine Studien zur Anwendbarkeit dieser Methode auf die Analyse ammoniumhaltiger Wasserproben. Daher wurde die Methode in dieser Arbeit für die Anwendbarkeit auf Wasserproben optimiert, insbesondere auf natürliche Grundwasserproben. Zum anderen wurde eine gängige Aufbereitungsmethode für gelöstes Nitrat weiterentwickelt. Dabei wurden die Vorbereitungs- und Arbeitszeit der Denitrifizierermethode verkürzt, ohne die Genauigkeit der Messung negativ zu beeinflussen. Zu diesem Zweck wurden zwei bestehende Varianten der Methode miteinander kombiniert und modifiziert. Als Eignungsprüfung der Methoden zur Prozessidentifikation erfolgte eine exemplarische Feldstudie. Als Modellstandort diente ein Untersuchungsgebiet im Südosten Berlins. Der Grundwasserleiter des Standortes ist u. a. durch eine massive Kontamination von Ammonium gekennzeichnet. Im Untersuchungsgebiet wurde das sogenannte BIOXWAND-Verfahren entwickelt und zur Sanierung auf den Grundwasserleiter angewandt. Dabei handelt es sich um ein in-situ-Verfahren, wobei eine direkte Injektion von Sauerstoff in den Grundwasserleiter erfolgt um Nitrifikation zu begünstigen. Für die isotopengestützte Prozessidentifikation wurden im Rahmen dieser Arbeit von 2016 bis 2019 zweimal jährlich Grundwasserproben aus dem BIOXWAND-Anstrom und dem BIOXWAND-Abstrom entnommen und mit den erarbeiteten Präparationsmethoden aufbereitet und analysiert. Zur Prozessidentifikation wurde ein analytisches Modell erstellt. Bei der vorliegenden kumulativen Dissertation handelt es sich um eine verkürzte Darstellung der Forschungsergebnisse. Die ausführlichen Ergebnisse wurden bereits in der Fachzeitschrift 'Rapid Communications in Mass Spectrometry' veröffentlicht.:VERZEICHNIS DER TABELLEN ................................................................................ 9 VERZEICHNIS DER ABBILDUNGEN ....................................................................... 10 VERZEICHNIS DER ANHÄNGE .............................................................................. 11 VERZEICHNIS DER SYMBOLE UND ABKÜRZUNGEN ............................................. 12 1 EINLEITUNG UND MOTIVATION ....................................................................... 14 2 ZIELSETZUNG UND KONZEPT ............................................................................ 16 3 THEORETISCHE EINFÜHRUNG .......................................................................... 18 3.1 Stickstoff in der Umwelt ........................................................................................ 18 3.2 Ammonium und Nitrat im Stickstoffkreislauf ........................................................... 18 3.3 Einflussfaktoren auf die Prozesse des Stickstoffkreislaufs ....................................... 21 3.4 Isotopenanalytik in den Umweltwissenschaften ...................................................... 22 3.4.1 Definition stabiler Isotope ................................................................................................... 22 3.4.2 Isotopieeffekte und Fraktionierung .................................................................................... 24 3.4.3 Delta-Notation ....................................................................................................................... 25 3.4.4 Fraktionierungs- und Anreicherungsfaktor ....................................................................... 28 3.5 Analyse stabiler Isotope mittels Isotopenverhältnis-Massenspektrometrie ................. 29 3.5.1 Allgemeine Informationen ................................................................................................... 29 3.5.2 Massenspektrometer ............................................................................................................ 29 3.5.3 Analyse stabiler Isotope mittels Elementaranalysator-Isotopenverhältnis-Massenspektrometrie-Kopplung (EA-IRMS) ...................................................................... 31 3.5.4 Analyse stabiler Isotope mittels GasBench II – IRMS ..................................................... 33 3.6 Ammonium und Nitrat im Kontext stabiler Isotope .................................................. 34 4 PROBENAUFBEREITUNGSMETHODEN ............................................................... 37 4.1 Bedeutung der Probenaufbereitung ....................................................................... 37 4.2 Probenaufbereitung für die δ15N-Isotopenanalyse von gelöstem NH4+ ....................... 37 4.2.1 Destillationsmethode ............................................................................................................ 37 4.2.2 Quecksilberfällung ................................................................................................................ 37 4.2.3 Diffusionsmethode ................................................................................................................ 38 4.2.4 Kationenaustausch................................................................................................................ 39 4.2.5 Fällung von Ammonium mittels Tetraphenylborat ........................................................... 39 4.2.6 Weitere Methoden ................................................................................................................ 40 4.3 Zusammenfassung der Probenaufbereitungsmethoden für die δ15N-Isotopenanalyse von gelöstem NH4+ ............................................................................................... 40 4.4 Probenaufbereitung für die δ15N- und δ18O-Isotopenanalyse von gelöstem NO3− ........ 41 4.4.1 Reduktionsmethoden ........................................................................................................... 41 4.4.2 Denitrifizierermethode ......................................................................................................... 41 4.4.3 Silbernitratfällung.................................................................................................................. 42 4.4.4 Bariumnitratfällung ............................................................................................................... 43 4.5 Zusammenfassung der Probenaufbereitungsmethoden für die δ15N- und δ18O-Isotopenanalyse von gelöstem NO3- ....................................................................... 43 5 ÜBERBLICK DER DURCHGEFÜHRTEN STUDIEN ................................................ 44 5.1 δ15N-Analyse von Ammonium in gefriergetrockneten, natürlichen Grundwasserproben durch Fällung mit Natriumtetraphenylborat ............................................................ 44 5.2 Weiterführende Optimierung der Denitrifizierermethode für die schnelle 15N und 18O-Analyse von Nitrat in natürlichen Wasserproben ..................................................... 44 5.3 Beispielhafte Identifizierung von Nitrifikation und Sorptionsprozessen von Ammonium als Feldstudie ...................................................................................................... 45 6 DISKUSSION UND AUSBLICK ............................................................................ 47 7 DANKSAGUNG ................................................................................................... 50 8 LITERATURVERZEICHNIS ................................................................................. 51 ANHANG ............................................................................................................... 61 / This thesis provides a method to identify the transformation of the nitrogen species ammonium and nitrate in polluted aquifers by analyzing the isotope ratios N-15 and O-18. Various preparation methods already exist, but are either labor intensive or time consuming and are therefore related with considerable costs. To achieve a broader applicability in environmental sciences, two simplified methods for the N-15 and O-18 stable isotope analysis of ammonium and nitrate in water were developed in this thesis. On the one hand, a precipitation method using sodium tetraphenylborate for the sample preparation of the N-15 isotope analysis for ammonium was modified, tested and validated. So far no studies could verify the applicability of this method for analysis of water samples containing ammonium. Therefore, the method was optimized for applicability to water samples, especially natural groundwater samples within this thesis. On the other hand, a common processing method for dissolved nitrate was optimized. The preparation and working time of the denitrification method was shortened without negatively affecting the accuracy of the measurement. For this purpose, two existing variants of the method were combined and modified. Furthermore, an exemplary field study was carried out to test the suitability of the preparation methods for process identification. A study area southeast of Berlin (Germany) containing an aquifer massively contaminated with ammonium served as a model location. Inside the area, the so-called BIOXWAND process, an in-situ process whereby oxygen is injected directly into the aquifer to promote nitrification, was developed and applied to the aquifer in terms of remediation. For isotope-based process identification, groundwater samples were taken twice a year from 2016 to 2019 from the BIOXWAND inflow and outflow and analyzed using the preparation methods developed. An analytical model was created for process identification.:VERZEICHNIS DER TABELLEN ................................................................................ 9 VERZEICHNIS DER ABBILDUNGEN ....................................................................... 10 VERZEICHNIS DER ANHÄNGE .............................................................................. 11 VERZEICHNIS DER SYMBOLE UND ABKÜRZUNGEN ............................................. 12 1 EINLEITUNG UND MOTIVATION ....................................................................... 14 2 ZIELSETZUNG UND KONZEPT ............................................................................ 16 3 THEORETISCHE EINFÜHRUNG .......................................................................... 18 3.1 Stickstoff in der Umwelt ........................................................................................ 18 3.2 Ammonium und Nitrat im Stickstoffkreislauf ........................................................... 18 3.3 Einflussfaktoren auf die Prozesse des Stickstoffkreislaufs ....................................... 21 3.4 Isotopenanalytik in den Umweltwissenschaften ...................................................... 22 3.4.1 Definition stabiler Isotope ................................................................................................... 22 3.4.2 Isotopieeffekte und Fraktionierung .................................................................................... 24 3.4.3 Delta-Notation ....................................................................................................................... 25 3.4.4 Fraktionierungs- und Anreicherungsfaktor ....................................................................... 28 3.5 Analyse stabiler Isotope mittels Isotopenverhältnis-Massenspektrometrie ................. 29 3.5.1 Allgemeine Informationen ................................................................................................... 29 3.5.2 Massenspektrometer ............................................................................................................ 29 3.5.3 Analyse stabiler Isotope mittels Elementaranalysator-Isotopenverhältnis-Massenspektrometrie-Kopplung (EA-IRMS) ...................................................................... 31 3.5.4 Analyse stabiler Isotope mittels GasBench II – IRMS ..................................................... 33 3.6 Ammonium und Nitrat im Kontext stabiler Isotope .................................................. 34 4 PROBENAUFBEREITUNGSMETHODEN ............................................................... 37 4.1 Bedeutung der Probenaufbereitung ....................................................................... 37 4.2 Probenaufbereitung für die δ15N-Isotopenanalyse von gelöstem NH4+ ....................... 37 4.2.1 Destillationsmethode ............................................................................................................ 37 4.2.2 Quecksilberfällung ................................................................................................................ 37 4.2.3 Diffusionsmethode ................................................................................................................ 38 4.2.4 Kationenaustausch................................................................................................................ 39 4.2.5 Fällung von Ammonium mittels Tetraphenylborat ........................................................... 39 4.2.6 Weitere Methoden ................................................................................................................ 40 4.3 Zusammenfassung der Probenaufbereitungsmethoden für die δ15N-Isotopenanalyse von gelöstem NH4+ ............................................................................................... 40 4.4 Probenaufbereitung für die δ15N- und δ18O-Isotopenanalyse von gelöstem NO3− ........ 41 4.4.1 Reduktionsmethoden ........................................................................................................... 41 4.4.2 Denitrifizierermethode ......................................................................................................... 41 4.4.3 Silbernitratfällung.................................................................................................................. 42 4.4.4 Bariumnitratfällung ............................................................................................................... 43 4.5 Zusammenfassung der Probenaufbereitungsmethoden für die δ15N- und δ18O-Isotopenanalyse von gelöstem NO3- ....................................................................... 43 5 ÜBERBLICK DER DURCHGEFÜHRTEN STUDIEN ................................................ 44 5.1 δ15N-Analyse von Ammonium in gefriergetrockneten, natürlichen Grundwasserproben durch Fällung mit Natriumtetraphenylborat ............................................................ 44 5.2 Weiterführende Optimierung der Denitrifizierermethode für die schnelle 15N und 18O-Analyse von Nitrat in natürlichen Wasserproben ..................................................... 44 5.3 Beispielhafte Identifizierung von Nitrifikation und Sorptionsprozessen von Ammonium als Feldstudie ...................................................................................................... 45 6 DISKUSSION UND AUSBLICK ............................................................................ 47 7 DANKSAGUNG ................................................................................................... 50 8 LITERATURVERZEICHNIS ................................................................................. 51 ANHANG ............................................................................................................... 61

Les polymères répondant au pH ou à la température deviennent hydrophobes à partir d’un pH ou d’une température critique. Associés à un bloc polymère hydrophile, ils peuvent former des micelles réversibles en solution aqueuse en réponse à un stimulus. Cette thèse décrit principalement la synthèse par polymérisation radicalaire contrôlée de copolymères à blocs triple hydrophiles de type ABC ou ACB, composés d’un bloc très hydrophile (PEO, bloc A), d’un bloc répondant à la température et au pH (PDMAEMA, bloc B) et d’un bloc cationique (PDMAEMAquat, bloc C). Leur caractérisation par chromatographie d’exclusion stérique en phase aqueuse s’est révélée peu concluante ; c’est pourquoi nous les avons analysés par RMN diffusionnelle. D’autre part, l’auto-assemblage en solution aqueuse de ces copolymère triblocs en fonction du pH et de la température a été étudié par RMN 1H et par DLS. Par ailleurs, le bloc C, cationique, forme un complexe hydrophobe avec un polymère chargé négativement (PSS). Les objets résultant de cette complexation entre le dernier bloc du tribloc ABC et le PSS ont été caractérisés par RMN 1H, par DLS, par RMN diffusionnelle et par TEM. Leur comportement en solution aqueuse en fonction du pH et de la température a également été abordé. / PH- or temperature-responsive polymers become hydrophobic from a critical pH or temperature. When they are associated to a hydrophilic block, they may respond to a stimulus by forming reversible micelles in aqueous solution. This thesis mainly deals with the synthesis by controlled radical polymerization of ABC- or ACB-type triple hydrophilic block copolymers, based on a highly hydrophilic block (PEO, A-block), a pH- and temperature-responsive moiety (PDMAEMA, B-block) and a cationic sequence (PDMAEMAquat, C-block). As their characterization by SEC in aqueous phase was not conclusive, they were therefore analyzed by diffusional NMR. In addition, their self-assembly in aqueous solution depending on pH or temperature was studied by 1H NMR and DLS. Furthermore, the cationic C-block form a so-called polyelectrolyte complex with a negatively charged polymer (PSS). Objects resulting from the complexation between the last block of ABC-triblock and PSS were characterized by 1H NMR, DLS, diffusional NMR and TEM. Their behavior in aqueous solution was also investigated depending on pH and temperature.

Environmental pollution has become a global concern as consequence of industrializa-tion and urbanization. The ongoing subsurface contamination by dense non-aqueous phase liquids (DNAPLs) bears tremendous hazardous potential for humans and ecosys-tems including aquifer systems. Intended or accidental spill events have led to a vast number of registered sites affected by DNAPL type chemicals. Despite the existence of novel techniques for their exploration, characterization and remediation, economical constraints often limit efforts for risk prevention or reduction, so that information and data to characterize highly complex DNAPL contamination scenarios are often insuffi-cient and compensated by natural attenuation of groundwater-dissolved contaminant plumes. Especially, knowledge on the DNAPL source zone geometry (SZG) and source zone formation are critically required yet very scarce. Against the previously stated background, this cumulative doctoral dissertation critically examined the processes of DNAPL source zone formation at laboratory scale. A comprehensive literature review identified current limitations and open research questions in the latter research field, revealing evidence for the relevance of SZG for plume response at different scales. Giv-en only a limited number of published studies related to DNAPL source zone formation, two simplified experimental setups mimicking source zone formation in an initially fully water-saturated aquifer were developed and intensively tested. The performance of aqueous and non-wetting phase dyes was evaluated for DNAPL release into three non-consolidated porous media using reflective optical imaging in combination with a cus-tom-made image processing and analysis (IPA) framework. The latter suite allowed for the generation of physically plausible DNAPL saturation distributions with determinable level of uncertainty. Then, a limited number of DNAPL release experiments were per-formed under controlled ambient as well as with boundary and initial conditions to generate robust observation data, while further adopting the IPA framework. The latter data was introduced into a numerical multiphase flow model. While most system pa-rameters could be directly determined, the parameters defining the capillary pressure-saturation and relative permeability-saturation retention curves were inversely deline-ated through a classical Monte Carlo analysis. Overall, the successfully calibrated nu-merical setup mimicking the transient DNAPL source zone formation allowed to quanti-fy uncertainties related to the experiment, IPA framework and model setup configura-tion. In addition, a number of new research questions pointing towards future im-provements of laboratory-scale methodologies to understand DNAPL contamination were derived. Especially in light of numerous existing contaminated sites with unclear history and even more vague future, given by potential impacts through climate change and anthropogenic activity, an increasing need for sophisticated strategies to better un-derstand DNAPL contamination and to reduce hazard potential is expected.:Statement I List of publications II Abstract VI Acknowledgements and funding information IX List of figures XIII List of tables XIV Abbreviations and symbols used in the main text XV 1 Introduction and background 1-1 1.1 Motivation of this thesis 1-1 1.2 Incorporation of this thesis in research projects 1-4 1.3 Definition of objectives and workflow strategy of this thesis 1-5 1.4 Formal structure of this thesis 1-11 2 Existing knowledge on DNAPL contamination 2-1 3 Fundamentals of DNAPL migration in porous media 3-1 3.1 Basic concepts for multiphase flow in porous media 3-1 3.2 Capillary pressure-saturation correlation 3-3 3.3 Relative permeability-saturation correlation 3-5 3.4 Balance equations for laminar fluid phase flow in porous media 3-7 4 Core research complex A : Development of a framework for the semi-automatized generation of DNAPL saturation distribution observation data 4-1 5 Core research complex B : Experimental and model-based simulation of DNAPL source zone formation 5-1 6 Summary and conclusions 6-1 6.1 Summary of perceptions for each main section of this thesis 6-1 6.2 New research questions with regard to DNAPL source zone formation at the laboratory scale 6-5 6.3 General recommendations for future works related to DNAPL contamination 6-8 References Ref-1 Appendix I : ENGELMANN ET AL. (2019a) App I-1 Published journal article App I-1 Appendix II : ENGELMANN ET AL. (2019b) App II-1 Published journal article App II-1 Electronic Supplementary Material 1 : Unprocessed raw TIFF format images used for IPA frame-work evaluation App II-26 Electronic Supplementary Material 2 : Sensitivities for color model change and binary conversion algorithms App II-36 Electronic Supplementary Material 3 :Relevance of spatially non-uniform illumination correction and background exclusion App II-76 Appendix III : ENGELMANN ET AL. (2021) App III-1 Published journal article App III-1 Electronic Supplementary Material 1 : Unprocessed raw TIFF format images for IPA framework ap-plication App III-30 Electronic Supplementary Material 2 : Processed images with all intermediate steps of IPA frame-work application App III-58 Electronic Supplementary Material 3 : IPA fitness App III-86 Electronic Supplementary Material 4 : Partial objective functions App III-87 Electronic Supplementary Material 5 : Model verification App III-93

No description available.

D. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology / A novel low-cost ternary Mn-Fe-Cu (MFC) metal oxide nanocomposite adsorbent was fabricated using facile co-precipitation method and successfully applied for the sequestration of Cr(VI) and As(III) from simulated aqueous efflent. The central composite design (CCD) of the response surface methodology (RSM) optimization technique determined the optimal working parameters for the preparation of the ternary MFC metal oxide nanocomposite. The spectroscopic microstructural analysis of the ternary MFC metal oxide nanocomposite was performed using fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) spectroscopy. The spectroscopic analyses revealed a rough surface with hydroxyl groups and the presence of mixed metal oxides in different valence states. The BET surface area, pore volume and pore size of the nanostructured MFC ternary metal oxide composite were found to be 77.2427 m2/g, 0.2409 cm3/g and 14.7560 nm, respectively. The pH drift method determined that the pHpzc of the adsorbent was 6.75. The batch technique was employed to investigate the adsorption dynamics (effects of ionic strength, co-existing anions, adsorbent regeneration and reuse) and optimum parameters (solution pH, adsorbent dosage concentration, desorption) of Cr(VI) and As(III) adsorption onto the MFC nanocomposite. The fitting of non-linear kinetic (pseudo-first-order, pseudo-second-order and Elovich), diffusion (intraparticle and Boyd) and isotherm (Langmuir, Freundlich and Dubinin-Radushkevich) models to the Cr(VI) and As(III) experimental adsorption data gave an insight into the adsorption mechanisms. The Langmuir adsorption capacities, qm (mg/g), were 168.71 at solution pH 3 and 35.07 at solution pH 9 for Cr(VI) and As(III) adsorption, respectively. The adsorption of Cr(VI) onto the ternary MFC metal oxide nanocomposite was physical and formed outer-sphere surface complexes through electrostatic interactions, while the removal of As(III) was specific due to inner-sphere surface complexation and ligand/ion exchange reactions. The results from XPS and FTIR analysis after the adsorption of Cr(VI) and As(III) showed that the surface hydroxyl groups on the MFC nanocomposite interacted with the Cr(VI) and As(III) species during the formation of the surface complexes. To facilitate ease of adsorbent removal from the treated simulated aqueous effluent, the ternary MFC metal oxide system was co-precipitated onto biochar support.

[pt] Os nanomateriais à base de TiO2 sensíveis à luz visível estão entre as alternativas mais promissoras para aplicações fotocatalíticas, como remediação ambiental. Os complexos de transferência de carga (CTCs) entre nano-TiO2 e ligantes bidentados, uma alternativa, têm sido amplamente estudados. No entanto, a eficiência da fotodegradação e o papel das espécies oxidantes reativas (ROS) não são totalmente compreendidos. Além disso, o desenvolvimento de CTCs baseados em TiO2 modificado com ácido malônico (MoA) ainda não foi investigado, até onde é sabido. Neste estudo, CTCs de TiO2-Acetilacetona (ACAC) e TiO2-MoA com alta área superficial foram sintetizados via sol-gel. Ambos os CTCs à base de TiO2preparados foram submetidos a testes de fotodegradação de tetraciclina e clorofenolcom e sem sequestrantes de ROS sob luz visível de baixa potência (26 W). Os CTCs TiO2-MoA foram totalmente caracterizadas por análises de DRX, MS-TGA, FTIR, adsorção-dessorção de N2, DRS, PL, EPR e XPS. A síntese sol-gel e o processo de calcinação adotado produziram CTCs de anatásio fortemente ligados (ligação covalente) com acetilacetona e ácido malônico, capazes de absorver ao longo do espectro visível quando calcinados a 300 graus C (TiO2-A300) e 270 graus C (TiO2-MoA270). Ambos os CTCs calcinados apresentam um único elétron preso na vacância de oxigênio (SETOV / centro de cores F+). Os CTCs TiO2-MoA-270 apresentaram áreas superficiais (>306 m2.g-1), volumes de mesoporos (>0,339 mL.g-1) e atividadefotocatalítica extremamente elevados, degradando aproximadamente 100 por cento de TC após 6 h. Os CTCs TiO2-MoA-270 e TiO2-A300 são uma fonte eficiente de geração de radicais *O2- e ineficientes geradores de radicais OH*. Os resultados desta pesquisa podem ser aplicados à síntese, via sol-gel, de outros CTCs, como os ácidos dicarboxílicos, e explorados em estudos posteriores sobre purificação do ar e produção de hidrogênio. / [en] Visible light-sensitive TiO2-based nanomaterials are among the most promising alternatives for photocatalytic applications, such as environmental remediation. The charge transfer complexes (CTCs) between nano-TiO2 and bidentate ligands, an alternative, have been widely studied. However, the photodegradation efficiency and role of reactive oxidizing species (ROS) are not fully understood. In addition, the development of CTCs based on TiO2 modified with malonic acid (MoA) have not yet been investigated, as far as the authors know. In this study, TiO2-Acetylacetone (ACAC) and TiO2-MoA CTCs with high surface area were synthesized via sol-gel route. Both as-prepared TiO2-based CTCs were subjected to tetracycline and chlorophenol photocatalytic degradation tests with and without ROS scavengers under low-power visible light (26 W). The TiO2-MoA CTCs were fully characterized by XRPD, MS-TGA, FTIR, N2 adsorption-desorption, DRS, PL, EPR and XPS analysis. The sol-gel synthesis and the calcination process adopted produced CTCs of nano-TiO2 anatase strongly bond (covalent bond) with acetylacetone and malonic acid, capable of absorbing along the visible spectrum when calcined at 300 degrees C (TiO2-ACAC-300) and 270 degrees C (TiO2- MoA-270). Both calcined CTCs present single electron trapped in oxygen vacancy (SETOV / F +color center). The TiO2-MoA-270 CTCs showed very high surface areas (>306 m2.g-1), mesopore volumes (>0.339 mL.g-1) and the highest photocatalytic activity, degrading approximately 100 percent of the TC after 6 h. The TiO2-MoA-270 and TiO2-A300 CTCs were an efficient source of *O2- radicals and inefficient generation of OH* radicals. The findings of this research can be applied to the synthesis, via sol-gel, of other CTCs, such as dicarboxylic acids, and explored in further studies on air purification and hydrogen production.

No description available.

Monte-Carlo calculations are used to simulate the stochastic effects of fast neutron-induced chemical changes in the radiolysis of the ferrous sulfate (Fricke) dosimeter. To study the dependence of the yield of ferric ions, G(Fe[superscript 3+]), on fast neutron energy, we have simulated, at 25 [degree centigrade], the oxidation of ferrous ions in aerated aqueous 0.4 M H[subscript 2]SO[subscript 4] (pH 0.46) solutions when subjected to ~0.5-10 MeV incident neutrons, as a function of time up to ~50 s. The radiation effects due to fast neutrons are estimated on the basis of track segment (or"escape") yields calculated for the first four recoil protons with appropriate weighting according to the energy deposited by each of these protons. For example, a 0.8-MeV neutron generates recoil protons of 0.505, 0.186, 0.069, and 0.025 MeV, with linear energy transfer (LET) values of ~41, 69, 82, and 62 keV/[micro]m, respectively. In doing so, we consider that further recoils make only a negligible contribution to radiation processes. Our results show that the radiolysis of dilute aqueous solutions by fast neutrons produces smaller radical yields and larger molecular yields (relative to the corresponding yields for the radiolysis of water by [superscript 60]Co [gamma]-rays or fast electrons) due to the high LET associated to fast neutrons. The effect of recoil ions of oxygen, which is also taken into account in the calculations, is shown to decrease G(Fe[superscript 3+]) by about 10%. Our calculated values of G(Fe[superscript 3+]) are found to increase slightly with increasing neutron energy over the energy range covered in this study, in good agreement with available experimental data. We have also simulated the effect of temperature on the G(Fe[superscript 3+]) values in the fast neutron radiolysis of the Fricke dosimeter from 25 to 300 [degree centigrade]. Our results show an increase of G(Fe[superscript 3+]) with increasing temperature, which is readily explained by an increase in the yields of free radicals and a decrease in those of molecular products. For 0.8-MeV incident neutrons (the only case for which experimental data are available in the literature), there is a ~23% increase in G(Fe[superscript 3+]) on going from 25 to 300 [degree centigrade]. Although these results are in reasonable agreement with experiment, more experimental data, in particular for different incident neutron energies, would be needed to test more rigorously our Fe[superscript 3+] ion yield results at elevated temperatures.

Chemical modification of proteins is critical for many areas of biochemistry and medicine. Several methods for site-selective protein modification are reported in this Thesis that are useful in accessing both natural and artificial protein architectures. Multiple, complementary methods for the conversion of cysteine to dehydroalanine are described. Dehydroalanine is used as a general precursor to several post-translational modifications and glycosylation, polyprenylation, phosphorylation, and lysine methylation and acetylation are all accessible. These modifications and their mimics were explored on multiple proteins, including histone proteins. Unnatural modifications were also explored. The first examples of olefin metathesis and Suzuki-Miyaura cross-coupling on protein substrates are reported. Allyl sulfides were discovered to be remarkably reactive substrates in olefin metathesis, allowing use of this reaction in water and on proteins. For Suzuki-Miyaura cross-coupling, a new catalyst is described that is fully compatible with proteins. Both olefin metathesis and cross-coupling allow the formation of carbon-carbon bonds on proteins. The prospects of these transformations in chemical biology are discussed. Finally, a novel strategy is reported for the installation of natural, unnatural, and post-translationally modified amino acid residues on proteins. This technology relies on addition of carbon radicals to dehydroalanine. This method of "chemical mutagenesis" is anticipated to complement standard genetic manipulation of protein structure.

Made available in DSpace on 2017-07-21T18:53:23Z (GMT). No. of bitstreams: 1 Doris Oliveira Gregianin.pdf: 1718205 bytes, checksum: 59a8cb966255e87e0fa3f347f2a191cb (MD5) Previous issue date: 2014-08-28 / The increased incidence of cardiovascular disease and various cancers have been the cause of searching for changing habits in a large portion of the population, seeking the physical activity in conjunction with the consumption of healthier foods with higher nutritional content. Considering the high biological value of the proteins of sweet whey and the recognized effect in reducing risk of cardiovascular disease of soy protein, the aim of this study was to develop a mixed chocolate-soluble soybean extract dissolved in sweet whey. The different proportions of carrageenan stabilizers, pectin and tapioca starch were defined by the experimental design of mixtures simplex centroid. By optimizing the response surface was definitely the best formulation in relation to the physic-chemical and sensory parameters. The simultaneous optimization of response variables indicated that the optimal formulation should contain 46% carrageenan and 54% pectin and 0% starch, with a desirability index of 0.929. The formulation indicated for the desirability function was made with water soluble soy extract dissolved in sweet whey and; on sweet whey with reduced lactose content. Serum was hydrolyzed by the action of lactase from Kluyveromyces lactis yeast enzyme at a concentration of 2500 NLU / L in reaction 4 hr at 37 ° C. The sensory attributes were evaluated by nine points hedonic scale and attitude scale in purchase intent. For overall impression, the formulations presented average value of 7.11 ±1.09, while purchase intent the average value was 3.99 ± 1.28, and the multiple regression models proved to be predictive. The most widely accepted formulations were those who had lower viscosity and instrumental containing pectin in its constitution. The results obtained indicate that the combination of sweet whey and soy aqueous extract is a viable option for the preparation of a chocolate beverage. It was also observed that the use of cassava starch as a thickener does not interfere negatively on the rheological and sensory characteristics and; that the combined carrageenan and pectin concentrations defined predictive model ensures greater acceptability of the product. / O aumento da incidência de doenças cardiovasculares e diversos tipos de câncer tem sido a causa da procura por mudanças de hábitos em grande parte da população, buscando-se a prática de atividades físicas em conjunto com o consumo de alimentos mais saudáveis, com maior valor nutricional. Considerando o alto valor biológico das proteínas do soro de leite doce e o reconhecido efeito na diminuição de risco de doenças cardiovasculares da proteína de soja, o objetivo deste trabalho foi desenvolver um achocolatado misto de extrato hidrossolúvel de soja dissolvido em soro de leite doce. As diferentes proporções dos estabilizantes carragena, pectina e amido de mandioca foram definidas pelo planejamento experimental de misturas simplex centróide. Através da otimização da Superfície de Resposta foi definida a melhor formulação em relação aos parâmetros físico-químicos e sensoriais. A otimização simultânea das variáveis de resposta indicou que a formulação ideal deveria conter 46% de carragena e 54% de pectina e 0% de amido, com um índice de desejabilidade de 0,929. A formulação indicada pela função de desejabilidade foi elaborada com extrato hidrossolúvel de soja dissolvido em soro de leite doce e; em soro doce com teor de lactose reduzido. O soro foi hidrolisado pela ação da enzima lactase proveniente da levedura Kluyveromyces lactis, na concentração de 2.500 NLU/L numa reação de 4 horas à temperatura de 37°C. Os atributos sensoriais foram avaliados pela escala hedônica de nove pontos e escala de atitude na intenção de compra. Para impressão global as formulações apresentaram valor médio 7,11 ±1,09, enquanto que para intenção de compra o valor médio foi de 3,99 ±1,28, sendo que os modelos de regressão múltipla mostraram-se preditivos. As formulações mais aceitas foram aquelas que apresentaram menor viscosidade instrumental e que continham pectina em sua constituição. Os resultados obtidos indicam que a combinação do soro doce de leite e extrato aquoso de soja é uma opção viável para a elaboração de uma bebida achocolatada. Também foi possível observar que o uso do amido de mandioca como espessante não interfere negativamente nas características reológicas e sensoriais do produto e; que a carragena e pectinas combinadas, nas concentrações definidas pelo modelo preditivo, garantem maior aceitabilidade ao produto.