Heterogeneous photocatalysis is an advanced oxidation technology widely applied in environmental remediation processes. It is a relatively safe and affordable technology with a low impact on the environment and has found applications in a number of fields from chemical engineering, construction and microbiology to medicine. It is not catalysis in the real sense of the word as the photons which initiate the desired photocatalytic reaction are consumed in the process. The cost of these photons is by far the limiting economic factor in its application. From a technical standpoint, the inefficient use of the aforementioned photons during the photocatalytic reaction is responsible for the limited adoption of its application in industry. This inefficiency is characterised by low quantum yields or photonic efficiencies during its application. The mechanism of the technique of controlled periodic illumination which was previously proposed as a way of enhancing the low photonic efficiency of TiO2 photocatalysis has been investigated using a novel controlled experimental approach; the results showed no advantage of periodic illumination over continuous illumination at equivalent photon flux. When the technique of controlled periodic illumination is applied in a photocatalytic reaction where attraction between substrate molecules and catalyst surface is maximum and photo-oxidation by surface-trapped holes, {TiIVOH•}+ ads is predominant, photonic efficiency is significantly improved. For immobilized reactors which usually have a lower illuminated surface area per unit volume compared to suspended catalyst and mass transfer limitations, the photonic efficiency is even lower. A novel photocatalytic impeller reactor was designed to investigate photonic efficiency in gas–solid photocatalysis of aromatic volatile organic compounds. The results indicate photonic efficiency is a function of mass transfer and catalyst deactivation rate. The development of future reactors which can optimise the use of photons and maximize photonic efficiency is important for the widespread adoption of heterogeneous photocatalysis by industry.

The diploma thesis presents the preparation of ,-bisterpyridinylfluorenes (unimers) containing fluorene unit in the central block either directly attached to terpyridine (tpy) end groups or via 1,4-phenylene or thiophene-2,5-diyl linker. Synthesized unimers were subsequently used for the preparation of metallo-supramolecular polymers with Zn2+ and Fe2+ ions. The prepared unimers were characterized by NMR, IR and HR-MS, their optical properties were investigated using absorption and emission spectroscopy and cyclic voltammetry. Molecular weight distribution for the prepared Fe-polymers was determined by GPC. The number-average degree of polymerization equal to 7 for an equimolar ratio between unimer and Fe2+ in a diluted solution was determined for polymers composed of unimer with thiophene-2,5- diyl linker. By using the viscometric measurements the ongoing constitutional dynamics in solutions of metallo-supramolecular polymers was proven. The overstoichiometric amount of metal ions in solution resulted in equilibrium shortening of the polymer chains together with end-capping of terminal tpy ligands by Mt2+ ions. Unimer with thiophene-2,5-diyl linker exhibited unique properties involving significantly red-shifted absorption and emission maxima, as well as the different behavior during assembling...

Made available in DSpace on 2017-07-24T19:37:52Z (GMT). No. of bitstreams: 1 Sheisa Fin Dantas.pdf: 1167838 bytes, checksum: d0aeeb3c6d878db48c73e057a5839964 (MD5) Previous issue date: 2015-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Organic micropollutants are substances that present even in small concentrations, are capable of triggering effects on systems where it is introduced, highlighting, among them the so-called endocrine disruptors (EDs). The EDs are substances that can interfere with the functions of the endocrine system, causing adverse effects to an organism or its offspring. Natural and synthetic sexual hormones are potent and EDs have been detected in aquatic environments on all continents, mainly due to the absence or deficiency in wastewater treatment processes. Humic substances (HS) are the main compounds able to interact with organic micropollutants such as hormones, interfering in the processes of bioavailability for the environment. Studies using HS as a complexing hormones have been carried out using the quantification method as chromatography. However, there are few studies of alternative methods for the quantification of estrogen hormones. The objective of this study was to validate and adapt a methodology to study estrone (E1), 17-estradiol (E2) and 17-ethinylestradiol (EE2) and study their interactions with humic substances employing molecular absorption spectroscopy Ultraviolet-Visible to quantify these hormones. This method is based on the diazotization of sulfanilamide with sodium nitrite, followed by coupling reaction with the hormone. Be established analytical curve for concentrations in the range from 10.0 to 28.0 μg mL-1 which was linear, adequate accuracy and precision. Despite the spectroscopic method is not selective, it presented results compatible with chromatography, which proves their suitability for the bench studies in this work. To perform a comparison between the methods employed to high performance liquid chromatography, using methanol and water as mobile phase and C-18 cartridge as stationary phase. For the study of interaction we used samples patterns of hormones in study and humic acid solution under constant agitation and samples taken within a maximum period of 48 hours. The reduction in the concentration of estrogen in the middle of the study, when in the presence of SH was detected since the beginning of the process. In all cases, we observed an increase in the removal of the hormone with increasing contact time. The reduction in the concentration of estrogen in the middle of the study, when in the presence of HSwas detected since the beginning of the process. In all cases, we observed an increase in the removal of the hormone with increasing contact time. By increasing the concentration of HS, there was an increase in the complexation of estrogens E2, and EE2 being that the hormone was EE2 that showed the best results of complexation with HS in the studied conditions. In aliquot removed from the system after 48 hours of stirring, was removed 51.1% (10.22 μg mL-1) in the presence of 10.0 μg mL-1 of the HS and 75.8% (15 16 μg mL-1) at 20 μg mL-1. The simulations can predict the behavior of E2 and EE2 hormones in natural aquatic environments rich in HS, where this interaction can reduce the availability to the biota and thus the absorption and physiological effects. / Os micropoluentes orgânicos são substâncias que mesmo presentes em pequenas concentrações, são capazes de desencadear efeitos sobre os sistemas em que são introduzidos, destacando-se, dentre eles, os chamados interferentes endócrinos (IEs). Os IEs são substâncias capazes de interferir nas funções do sistema endócrino, causando efeitos adversos a um organismo ou a sua prole. Hormônios sexuais naturais e sintéticos são potentes IEs e têm sido detectados em ambientes aquáticos em todos os continentes, principalmente em função da inexistência ou deficiência nos processos de tratamento de esgotos. Substâncias húmicas (SH) são os principais compostos capazes de interagir com micropoluentes orgânicos como os hormônios, interferindo nos processos de biodisponibilidade para o ambiente. Estudos usando SH como complexante de hormônios têm sido realizados utilizando-se a cromatografia como método de quantificação. Porém, existem poucos estudos de métodos alternativos para a quantificação de hormônios estrógenos. O objetivo deste trabalho foi validar e adaptar uma metodologia para estudar estrona (E1), 17-estradiol (E2) e 17α-etinilestradiol (EE2) e estudar suas interações com substâncias húmicas empregando-se espectroscopia de absorção molecular Ultravioleta-Visível para quantificação desses hormônios. Este método é baseado na diazotação da sulfanilamida com nitrito de sódio, seguida da reação de acoplamento com o hormônio. Foi possível estabelecer curva analítica para concentrações na faixa de 10,0 a 28,0 g mL-1 que apresentou linearidade, exatidão e precisão adequadas. Apesar do método espectroscópico não ser seletivo, o mesmo apresentou resultados compatíveis com a cromatografia, o que comprova sua adequação para os estudos de bancada realizados nesse trabalho. Para realizar um comparativo entre os métodos, empregou-se a cromatografia líquida de alta eficiência, utilizando-se metanol e água como fase móvel e cartucho C-18 como fase estácionária. Para o estudo de interação utilizou-se as amostras padrões dos hormônios em estudo e solução de ácido húmico, sob agitação constante e coletas realizadas no período máximo de 48 horas. A redução na concentração dos estrogênios no meio de estudo, quando em presença de SH foi detectada desde o início do processo. Para todos os casos, observou-se um aumento na remoção do hormônio com o aumento do tempo de contato. Ao aumentar-se a concentração de SH, observou-se um aumento na complexação dos estrogênios E2, e EE2 sendo que o hormônio EE2 foi o que apresentou os melhores resultados de complexação com a SH nas condições estudadas. Na alíquota retirada do sistema, após 48 horas de agitação, removeu-se 51,1% (10,22 μg mL-1) em presença de 10,0 μg mL-1 de SH e 75,8% (15,16 μg mL-1) em 20 μg mL-1. As simulações permitem prever o comportamento dos hormônios em ambientes aquáticos naturais ricos em SH, nos quais essa interação pode reduzir a disponibilidade para a biota e assim, a absorção e os efeitos orgânicos.

Atmospheric aldol self-reactions of octanal, heptanal and hexanal in a range of aqueous H2SO4 w/v% concentrations as a catalyst were studied in both bulk liquid-liquid experiments and gas-liquid experiments. Initially, a new practical methodology was developed and enhanced to monitor aldol reactions in aqueous acidic media. The evaluation of a quenching and extracting method were performed, confirming the suitability, reliability and reproducibility of the extraction method. In bulk studies, aldol products of the three aldehydes were separated and identified by preparative HPLC, GC-MS and NMR. The major aldol products observed at high acid concentrations were alpha,β-unsaturated aldehyde (dimer), trialkyl benzene (trimer) and tetraalkylcycloocta-tetraene (tetramer). The trimer of octanal was formed as trioxane in low sulfuric acid concentration and the possible mechanism accretion reaction pathways of high and low acid concentrations are proposed in this study. A systematic kinetic study of octanal, heptanal and hexanal in the bulk experiments at 65, 60 and 55 w/v% H2SO4 at 294 K were monitored using gas chromatographic equipped with a flame ionisation detector (GC-FID). The rate constants were generally estimated using second order kinetics and observed to increase as a function of sulfuric acid concentrations and also as the chain length of aliphatic aldehyde increased. The aldol self-reaction in the bulk experiment was too fast at room temperature to be easily measured using a quenching method therefore attempts were made to follow the reaction at low temperature (0 °C). The result at low temperature indicated that the rate constant of aldehyde was reduced but there was an issue of rapid rise in temperature as a result of mixing concentrated sulfuric acid with aqueous solution of the aldehyde. A gas bubbling system was developed which better simulates atmospheric reality, and which also resolves the issue of temperature rise on mixing. Two different methodologies were used: one in which the aldehyde was continually added, and one where a fixed amount was added from the gas phase and the reaction was then allowed to proceed, monitored at selected time intervals. The precision and accuracy of the fixed method was then further improved by the addition of an internal standard (IS). Using this, the concentrations of aliphatic aldehydes (C6-C8) were calibrated using an experimentally determined response factor and used to follow the loss of the reactant aldehydes. Similar methods were applied to the aldol dimers (C6-C8), which were purified and used to calibrate the chromatographic response. The rate constant for octanal, heptanal and hexanal at 76 wt% and 294 K were 0.0969 M-1 s-1, 0.1497 M-1 s-1 and 0.2622 M-1 s-1 respectively. There are some observations based upon the results presented in this thesis that may be of atmospheric significance: (i) phase separation between organic and aqueous layers in both the bulk experiment and in the bubbling system; (ii) the acid strength dependence and concentration-dependence of the various products; (iii) the faster rates than previously reported, and variation between bulk and bubbling; and (v) the time-dependent colour changes. Further work to explore these observations is proposed.

This thesis summarizes the outcome of work performed withthe objective to contribute to the knowledge and development ofthe kraft cooking process using spectrophotometricinterfaces. In kraft cooking, it is desirable to maximize the removal oflignin in the cook without loss of pulp strength. Theselectivity can be improved by exchanging some of the hydrogensulfide ion in the white liquor for polysulfides. Paper Ipresents a spectrophotometric method for in-line monitoring ofthe electrochemical production of polysulfide using anATR-probe for the UV-Vis range. A linear relation existsbetween the ATR-probe response and the concentration ofabsorbing species. Thus the process can be followed by simplemonitoring of a few wavelengths. A spectrophotometric monitoring system using a durableNafion ionomer membrane interface for continuous on-linemeasurement of sulfide and dissolved lignin during kraftcooking has previously been developed by our group. In paperII, the permeation of low molecular weight anions from liquorshaving high ionic strengths through a membrane in Na+ form hasbeen studied. A general relation between penetration and ionsize approximated by molecular weight has been established. Thepenetration of different anions can be explained as a diffusionthrough the winding membrane channels. Further the differentanions transport independently without being interfered by thesample matrix. In light of this validation, we applied the membraneinterface to the determination of anthraquinone-2-sulfonate(AQ-S) in alkaline pulping liquor. In paper III, a simple andrapid spectrophotometric method was developed and implementedon real samples. Interferences from other compounds penetratingthe membrane were minimized by reduction of the penetrated AQ-Sand measurement at 520 nm. This method is quick and can be usedon-line. Further, we extended the method to determination ofanthraquinone (AQ) in pulping liquor (paper IV). Although AQ isregarded as insoluble, it was found that the apparentsolubility of AQ in alkaline solutions increases considerablyin the presence of lignin, reaching 0.14 g/L at 90 oC. Thismakes the calibration of AQ possible. Time-resolvedmeasurements of dissolved AQ in 3 kraft-AQ pulping processeswere performed. The results show that the membrane has great potential aspart of a selective interface in applications where theconcentrations of small anions are to be monitored in mediawith high ionic strength. Keywords: Kraft cooking, On-line, Sulfide, Lignin,Polysulfide excess sulfur, Anthraquinone-2-Sulfonate (AQ-S),Anthraquinone (AQ), Nafion Membrane, UV-Vis, ATR-probe,Spectrophotometric.

This Thesis is a characterization study on substances having potency as drugs as well as on a lipid based drug-delivery matrix. The optical properties of newly synthesized molecules with proven pilicide properties have been characterized with several spectroscopic methods. These methods include optical absorption and fluorescence as well as time-resolved fluorescence. Upon covalently linking compounds with high quantum yields of fluorescence to specific parts of the pilicide, the biological impact was found to increase for some of the derivatives. Furthermore, by expanding the aromatic part of the pilicide molecule, a significant increase in the inherent fluorescence was obtained. The S0-S1 absorption band for these molecules was found to originate from an impure electronic transition, vibronically promoted by intensity borrowing from higher electronic states. Included in this Thesis is the measurement of how deeply some in this class of newly synthesized molecules become situated when placed inside ganglioside GM1 micelles, and how the molecules’ reorientation is affected. By means of radiation-less energy transfer, it was shown that the molecules place themselves close to the hydrophobic-hydrophilic interface inside the GM1 micelles. As a consequence they are exposed to a densely packed environment, which inhibits the free tumbling of the molecule. This restricted tumbling could be measured by means of time-resolved depolarization experiments. The release of drug-like fluorescent molecules is investigated from a lipid mixture, which upon equilibrium with water forms a mixture of inverted hexagonal and cubic phases. The lipid matrix displayed an extended release over the course of weeks, in vitro, for molecules having a large variation in hydrophobicity.

Diverse conformational transitions and aggregations of regioregular head-to-tail polyhexylthiophene in different environments have been studied by means of AFM and UV-vis spectroscopy. A helical conformation of the main chain with 12 thiophenes rings per each helical turn has been proposed. Length of the particles varies from several nanometers to several hundreds nanometers and can be adjusted by the solvents composition or concentration of PATs. Such well-defined organic semiconductor 1D particles can be used as building blocks for future nanoscale and molecular level electronic devices. Oligothiophenes represent one of the most promising class of semiconductive materials for FET fabrication because of their good mobility and environmental stability. However, most of unsubstituted oligothiophenes are insoluble that suppresses their potential industrial utility. On the first stage of the work, conformation, crystalline structure, molecular packing and charge carrier mobility of the highly soluble regiochemically pure [Beta]-substituted sexithiophene were systematically studied. It was found that [Beta, Beta´]-DH6T possesses moderate PR-TRMC charge carrier mobility, but rather low field-effect mobility. The investigation showed that such a poor macroscopic electrical properties of [Beta, Beta´]-DH6T originate neither from the twist of the conjugated system nor from the crystalline disorder, but rather from low-dense crystalline packing and "wrong" molecular orientation. To overcome these obstacles two thiophene-based azomethines were designed to optimize a solubility, self-assembly, and a charge carrier mobility. The idea was to utilize the ability of the amide group to form strong hydrogen bonds in non-polar solvents and in solid state, but to be easily broken in presence of polar solvents. Thus, at the stage of a dissolution and a deposition, when the solubility is important, the hydrogen bonding can be "switched off" simply by addition of polar solvents and then, after the removal of polar additives, the self-assembly can be "switched on". It was found that incorporation of azomethine and amide moieties in the [Alpha, Omega]-position, and hexyl chains in [Beta]-position of quaterthiophene, indeed considerably improves the self-assembly properties without suppression of the solubility. Self-assembly of azomethine oligomers with (QT-amide) and without amide moieties (QT-aniline) were monitored by UV-vis, XRD, and AFM. It was found that QT-amide, processed from solution, forms highly ordered layered (terrace) structures. This aggregation mode is similar to the self-assembly of unsubstituted conjugated oligomers (such as pentacene) occurred upon their evaporation in vacuum. The sum of charge carrier mobilities (PR-TRMC data) for QT-aniline was shown to be below the detectable limit, but the mobility of QT-amide was determined to be 1.10-2 cm2 V-1 s-1. The later is comparable with the mobilities of the best organic semiconductors. All these significant differences in properties of related compounds can be attributed to the hydrogen bonding between QT-amide molecules responsible for the observed self-assembly.

Die vorliegende Arbeit befasst sich mit Untersuchungen zur Komplexbildung von Cu2+, Zn2+, sowie Sn2+ und B(OMe)3 mit den Schiff-Basen aus 3-Aminopropyl-triethoxysilan (APTES) und 3-(2-Aminoethyl-amino)-propyl-trimethoxysilan (AEPTMS) mit α-Hydroxybenzocarbonylverbindungen. Die Liganden und die Komplexe wurden mit IR-, UV/VIS- und NMR-Spektroskopie charakterisiert. IR-Untersuchungen zeigen die charakteristischen C=N- und C=O-Valenzschwingungen. Sie werden durch die Komplexbildung deutlich verschoben. Die 1H- und 13C-NMR-Messungen indizieren die Komplexbildung mit einer signifikanten Verschiebung in den Signallagen der H- und C-Nachbaratome der Donatoratome. 29Si-NMR-Messungen indizieren keine Hydrolyse- und Kondensationsreaktionen im Verlauf der Synthese. Bei der Komplex-Synthese mit wasserhaltigen Übergangsmetallsalzen wurden Produkte von Sol-Gel-Prozessen gefunden. UV/VIS-spektroskopische Untersuchungen an den Mischungen der Übergangsmetallsalze mit APTES bzw. AEPTMS zeigen die Bildung typischer Aminkomplexe.

The groundwater bacterium Pseudomonas fluorescens (CCUG 32456) isolated at a depth of 70 m in the Äspö Hard Rock Laboratory secretes a pyoverdin-mixture with four main components (two pyoverdins and two ferribactins). The dominant influence of the pyoverdins of this mixture could be demonstrated by an absorption spectroscopy study. The comparison of the stability constants of U(VI), Cm(III), and Np(V) species with ligands simulating the functional groups of the pyoverdins results in the following order of complex strength: pyoverdins (PYO) > trihydroxamate (DFO) > catecholates (NAP, 6­HQ) > simple hydroxamates (SHA, BHA). The pyoverdin chromophore functionality shows a large affinity to bind actinides. As a result, pyoverdins are also able to complex and to mobilize elements other than Fe(III) at a considerably high efficiency. It is known that EDTA may form the strongest actinide complexes among the various organic components in nuclear wastes. The stability constants of 1:1 species formed between Cm(III) and U(VI) and pyoverdins are by a factor of 1.05 and 1.3, respectively, larger compared to the corresponding EDTA stability constants. The Np(V)-PYO stability constant is even by a factor of 1.83 greater than the EDTA stability constant. The identified Np(V)-PYO species belong to the strongest Np(V) species with organic material reported so far. All identified species influence the actinide speciation within the biologically relevant pH range. The metal binding properties of microbes are mainly determined by functional groups of their cell wall (LPS: Gram-negative bacteria and PG: Gram-positive bacteria). On the basis of the determined stability constants raw estimates are possible, if actinides prefer to interact with the microbial cell wall components or with the secreted pyoverdin bioligands. By taking pH 5 as an example, U(VI)-PYO interactions are slightly stronger than those observed with LPS and PG. For Cm(III) we found a much stronger affinity to aqueous pyoverdin species than to functional groups of the cell wall compartments. A similar behavior was observed for Np(V). This shows the importance of indirect interaction processes between actinides and bioligands secreted by resident microbes.

<p>This thesis summarizes the outcome of work performed withthe objective to contribute to the knowledge and development ofthe kraft cooking process using spectrophotometricinterfaces.</p><p>In kraft cooking, it is desirable to maximize the removal oflignin in the cook without loss of pulp strength. Theselectivity can be improved by exchanging some of the hydrogensulfide ion in the white liquor for polysulfides. Paper Ipresents a spectrophotometric method for in-line monitoring ofthe electrochemical production of polysulfide using anATR-probe for the UV-Vis range. A linear relation existsbetween the ATR-probe response and the concentration ofabsorbing species. Thus the process can be followed by simplemonitoring of a few wavelengths.</p><p>A spectrophotometric monitoring system using a durableNafion ionomer membrane interface for continuous on-linemeasurement of sulfide and dissolved lignin during kraftcooking has previously been developed by our group. In paperII, the permeation of low molecular weight anions from liquorshaving high ionic strengths through a membrane in Na+ form hasbeen studied. A general relation between penetration and ionsize approximated by molecular weight has been established. Thepenetration of different anions can be explained as a diffusionthrough the winding membrane channels. Further the differentanions transport independently without being interfered by thesample matrix.</p><p>In light of this validation, we applied the membraneinterface to the determination of anthraquinone-2-sulfonate(AQ-S) in alkaline pulping liquor. In paper III, a simple andrapid spectrophotometric method was developed and implementedon real samples. Interferences from other compounds penetratingthe membrane were minimized by reduction of the penetrated AQ-Sand measurement at 520 nm. This method is quick and can be usedon-line. Further, we extended the method to determination ofanthraquinone (AQ) in pulping liquor (paper IV). Although AQ isregarded as insoluble, it was found that the apparentsolubility of AQ in alkaline solutions increases considerablyin the presence of lignin, reaching 0.14 g/L at 90 oC. Thismakes the calibration of AQ possible. Time-resolvedmeasurements of dissolved AQ in 3 kraft-AQ pulping processeswere performed.</p><p>The results show that the membrane has great potential aspart of a selective interface in applications where theconcentrations of small anions are to be monitored in mediawith high ionic strength.</p><p>Keywords: Kraft cooking, On-line, Sulfide, Lignin,Polysulfide excess sulfur, Anthraquinone-2-Sulfonate (AQ-S),Anthraquinone (AQ), Nafion Membrane, UV-Vis, ATR-probe,Spectrophotometric.</p>