Layer-by-layer assembly of polyelectrolytes is a simple technique based on the self-assembly of polycations and polyanions mainly by electrostatic interactions, which has gained considerable scientific interest for its versatility of applications. Ease of fabrication process, inexpensive approach and use to coat surfaces with various geometries prompts the researchers to select this technique not only for the surface modification applications but also to study the processes which exploit the 3D matrix properties of polyelectrolyte multilayer films (PEMs). Recent advances have been made where PEMs coatings have been utilized for their bio-applications like drug delivery and in tissue engineering for modifying the biomaterial's surfaces. In the field of drug delivery and tissue engineering the location and availability of the constituent molecules is very important, which is defined by their ability to diffuse through the encapsulating material or reservoir. So the main objective of this thesis is to understand the transport of molecules in ultrathin Polyelectrolyte Multilayer Films in lateral as well as transverse direction to the substrate. To study this transport behaviour in PEMs, we have employed various strategies which can enhance or suppress the diffusivity across PEMs. Thus, understanding the diffusion at nanoscale resolution will lead us to design better host materials for loading of drugs and growth factors for various biomedical applications.

La sûreté du stockage des déchets radioactifs repose en grande partie sur la capacité de confinement du conteneur et de l’ouvrage qui lui sont dédiés. Dans le cas des déchets radioactifs de Faible et Moyenne Activité à Vie Courte (FMA-VC), cette propriété de confinement, assurée par des matrices solides à base de matériaux cimentaires, est mesurée sur la base d’un essai de diffusion naturelle, consistant à faire traverser un traceur, de type radioactif, dans un échantillon représentatif, duquel on retire, a posteriori, un coefficient de diffusion. L’évolution de ces matériaux et les améliorations apportées à la fabrication de nouvelles enveloppes de confinement induisent des durées d’essai pouvant atteindre plusieurs années.L’objectif premier de ce travail consiste en la détermination du coefficient de diffusion effectif d’une espèce de référence, qui sera dans notre cas l’eau tritiée, dans un intervalle de temps réduit. L’approche théorique repose sur la compréhension du phénomène de transport d’espèces ioniques en solution soumises à un champ électrique. Sur les bases d’un protocole expérimental clairement établi et de la définition du facteur de formation, caractéristique topologique intrinsèque du réseau poreux, il a été possible de déterminer le coefficient de diffusion effectif de l’eau tritiée d’une gamme de bétons et de mortier d’intérêt, et cela en seulement quelques heures.Dans un second temps, la comparaison de l’essai de migration sous champ électrique constant, développé dans ce travail, avec l’essai classique de diffusion naturelle à l’eau tritiée a mis en exergue deux points cruciaux. La non-prise en compte de la décroissance radioactive du tritium dans l’interprétation de l’essai de diffusion naturelle à l’eau tritiée amène une sous-estimation non-négligeable de la valeur du coefficient de diffusion. La conservation, lors de leur phase de maturation, des matériaux d’essais dans des conditions inadaptées, induit des mesures selon la technique de migration sous champ électrique constant disparates et non répétables.Dans un dernier temps, la validation complète de la technique électrocinétique, sujet initial de ce travail, repose sur la vérification des hypothèses théoriques énoncées au préalable. Le facteur de formation, et a fortiori le coefficient de diffusion effectif, est une grandeur indépendante de la force ionique de la solution porale du matériau considéré, cela pour une gamme de solution courante dans le domaine des matériaux cimentaires. Le facteur de formation s’avère aussi indépendant de l’amplitude du champ électrique appliqué, aussi pour une gamme et des durées d’essai adaptées aux conditions de mesures définies dans le protocole. Enfin, lorsque les valeurs de coefficients de diffusion effectifs obtenues en migration et diffusion naturelle à l’eau tritiée sont comparées sur plusieurs formulations maîtrisées de matériaux cimentaires / The safety and the reliability of a radioactive waste repository rely essentially on the confinement ability of the waste package and the storing structure. In the case of the low-level and intermediate level short-lived radioactive waste, the confinement property, relying on solid matrices made of cement-based materials, is assessed through a natural diffusion test, using a radioactive tracer, from which an effective diffusion coefficient is deduced. The evolution of the materials and more particularly the enhancement of the confinement properties of cement-based materials lead to test duration from a couple of months to a couple of years.The main objective of the present work involves the determination of the effective diffusion coefficient of reference chemical species, in our case the tritiated water, within a shorter time. The theoretical foundation is based on the description of ionic species mass transfer under the effects of an electrical field. With the definitions of a precise experimental protocol and of a formation factor, considered as an intrinsic topological feature of the porous network, it is possible to determine the effective diffusion coefficient of tritiated water for various types of concretes and mortars, and this within a few hours only.The comparison between the developed accelerated test, based on the application of a constant electrical field, and the normed natural diffusion test, using tritiated water, underlined two critical issues. First, omitting the impact of the radioactive decay of tritium during a natural diffusion test, leads to a non-negligible underestimation of the effective diffusion coefficient. Second, maintaining samples in high relative humidity conditions after casting is essential in order to avoid contrasted and unrelated results when performing the electrokinetic tests.Eventually, the validation of the electrokinetics technique, main objective of this work, rests on the assessment of the theoretical hypothesis previously formulated. The formation factor, as well as the effective diffusion coefficient, does not depend on the ionic strength of the material pore solution, this being validated for solutions of different composition encompassing the cement materials pore solution diversity. The formation factor also does not vary when the amplitude of the applied electrical field varies, provided both the test duration and the electrical field amplitude are kept within acceptable boundaries. Finally, the comparison between the values of the effective diffusion coefficient obtained with both the constant field migration test and the natural diffusion techniques, for perfectly conditioned and prepared materials, leads us to invalidate the assumption that the effects of the double electrical layer are negligible

Les sels d’aluminium sont utilisés par l’industrie cosmétique comme actifs anti-transpirants pour limiter la sudation. Leur mécanisme d’action, lié en partie à leur structure très complexe, est encore mal élucidé. Le développement de nouveaux outils de caractérisation pour améliorer la compréhension de leur action anti-transpirante au niveau moléculaire est donc crucial, pour, à terme, optimiser leur utilisation, voire pouvoir les remplacer par d’autres composés actifs. L’objectif de ce travail de thèse a été, d’une part, de caractériser, par une nouvelle approche analytique, les oligomères contenus dans les chlorhydrates d’aluminium (ACH) utilisés comme agents anti-transpirants et, d’autre part, d’étudier les interactions entre ces ingrédients cosmétiques et des protéines modèles. Dans une première partie, une méthode en électrophorèse capillaire de zone (CZE) a été développée pour la séparation, la caractérisation et l’analyse quantitative de la distribution des oligomères d’ACH (notamment, Al13 et Al30). Les choix du contre-ion, de la force ionique et du greffage du capillaire se sont révélés cruciaux pour le succès de la séparation, la stabilité des espèces au cours du processus électrophorétique et la répétabilité / reproductibilité de la séparation. L’optimisation des paramètres de séparation a permis d’étendre l’application de cette méthode à l’analyse d’autres espèces oligomères et colloïdales de l’aluminium, et de mettre en place un couplage en ligne avec l’analyse de la dispersion de Taylor (TDA). L’isotachophorèse capillaire (ITP) a également été explorée pour l’analyse d’échantillon à des concentrations élevées en ACH, se rapprochant de celles des formules anti-transpirantes. Les résultats obtenus montrent qu’il est possible d’analyser des échantillons jusqu’à 40 g/L en ACH. Enfin, le mécanisme d’obstruction du canal sudoripare semblant impliquer des phénomènes de complexations entre les oligomères d’aluminium et des protéines de la sueur lors de l’application de l’antitranspirant, l’enjeu du dernier volet de la thèse a été de développer une méthode en électrophorèse capillaire d’affinité (ACE) pour l’étude des interactions entre ACH et des protéines modèles (BSA et lysozyme). Pour cela l’électrolyte utilisé en ACE est uniquement constitué de ligands (ACH), sur une gamme de concentrations élevée (jusqu’à 50 g/L), afin de se rapprocher des conditions d’application. D’un point de vue analytique, le défi de ce travail a été de corriger les mobilités électrophorétiques des protéines des paramètres expérimentaux variant avec la concentration en ACH (échauffement par effet Joule, viscosité, état de charge de la protéine en fonction du pH, force ionique). Il a été possible de mettre en évidence des différences quantitatives de comportement électrophorétique traduisant des différences d’interaction entre les deux protéines modèles étudiées (BSA et lysozyme) et les ACH. / Aluminum chlorohydrates (ACH) are used by the cosmetics industry as antiperspirant active ingredients to limit sweating. Their mechanism of action, is still poorly understood. The development of new characterization tools to improve the understanding of their antiperspirant action at the molecular level is therefore crucial, to ultimately optimize their use, or even to replace them with other active compounds. The purposed of this work, was to characterize by a new analytical approach the oligomers contained in ACH and to study their interactions with model proteins. In a first part, a method was developed by capillary electrophoresis zone (CZE) for the separation, characterization and quantitative analysis of ACH oligomers (in particular Al13 and Al30). The choice of counter-ion, ionic strength and capillary coating was crucial for the success of the separation, the stability of the species during the electrophoretic process and the repeatability / reproducibility of the separation. The optimization of the separation conditions has made it possible to the separation of other oligomeric and colloidal species of aluminum, and to set up an on-line coupling of CZE to Taylor dispersion. analysis (TDA). Capillary isotachophoresis (ITP) was also explored for ACH analysis at high concentrations, close to those used in antiperspirant formulations. It was shown that it is possible to analyze samples up to 40 g / L in ACH. Finally, interactions of ACH with model proteins (BSA and lysozyme) were studied by capillary affinity electrophoresis (ACE) to shed more light on the phenomena of complexation leading to the obstruction of the sweat duct. The electrolyte used in ACE consists solely of ligands (ACH), at relatively high concentrations (up to 50 g / L), in order to mimic the conditions of application. From an analytical point of view, the challenge of this work was to correct the electrophoretic mobilities of the proteins from the experimental parameters varying with the concentration ACH (Joule heating, viscosity, state of charge of the protein as a function of the pH, ionic strength). It was possible to quantitatively demonstrate differences in the interactions between ACH and the two studied model proteins (BSA and lysozyme).

L’objectif de cette thèse est d’étudier les interactions entre polyélectrolytes (PE) de charges opposées par analyse frontale continue en électrophorèse capillaire (FACCE) et par titration calorimétrique isotherme (ITC), en fonction de la force ionique du milieu et des paramètres physico-chimiques relatifs aux deux partenaires (taux de charge chimique, masse molaire, ramification). Un copolymère statistique d’acrylamide et de 2-acrylamido-2-méthyl-propane sulfonate (PAMAMPS) de taux de charge variant entre 15% et 100% a été synthétisé et caractérisé pour cette étude. En tant que polycation modèle, la poly(L-lysine) a été retenue, sous sa forme linéaire (PLL) ou ramifiée / hyperbranchée (DGL). Des mesures par turbidimétrie ont permis d’étudier la stabilité des complexes de polyélectrolytes (PEC) en fonction de la force ionique du milieu. La détermination de la stœchiométrie des PEC par 1H-RMN a permis d’établir une règle générale pour prédire les stœchiométries de charge des PEC. Les paramètres thermodynamiques d’interactions (constantes et stœchiométries d’interaction, contribution entropique et enthalpique) ont été déterminés, par le tracé systématique des isothermes d’adsorption, en considérant le modèle d’interactions des sites indépendants de même énergie. Une dépendance linéaire entre le logarithme des constantes d’interactions et le logarithme de la force ionique a été observée. Cette dépendance en force ionique confirme le caractère entropique des interactions entre PE de charges opposées. Elle permet aussi de quantifier le nombre de contre-ions relargués lors de la formation du PEC. Cette quantité de contre-ions libérés a pu être comparée à la quantité totale de contre-ions condensés. Cette modélisation permet, en outre, de prédire les constantes d’interaction pour des taux de charge intermédiaires et à différentes forces ioniques. / The aim of this thesis is to study the interactions between oppositely charged polyelectrolytes (PE) by frontal analysis continuous capillary electrophoresis (FACCE) and isothermal titration calorimetry (ITC) as a function of the ionic strength of the medium and the physico-chemical properties related to the two partners (chemical charge density, molar mass, ramification). Statistical copolymers of acrylamide and 2-acrylamido-2-methyl-propane sulfonate (PAMAMPS) with chemical charge densities varying between 15% and 100% were synthesized and characterized for this study. Poly(L-lysine) under their linear (PLL) or ramified/hyperbranched (DGL) forms were used as model polycations. Turbidity measurements allowed the study of the stability of the polyelectrolyte complexes (PEC) as a function of the ionic strength of the medium. PEC charge stoichiometries were measured by 1H-NMR, and a general predictive rule that estimates the PEC charge stoichiometry was enounced. The thermodynamic binding parameters (binding constant, stoichiometry, enthalpic and entropic contributions) were determined, by systematically plotting the isotherms of adsorption, and using the model of independent and identical interacting sites. A linear dependence between the logarithm of the binding constants and the logarithm of the ionic strength was observed. This linear dependence confirmed the entropic character of the interactions between oppositely charged PE and allowed quantifying the number of released counter-ions that were compared to the total number of condensed counter-ions. Furthermore, this modelling allowed predicting the binding constants for intermediate chemical charge densities and at different ionic strengths.

Submitted by Lucas Custodio Recco null (recco_natacao@yahoo.com.br) on 2016-11-16T18:05:08Z No. of bitstreams: 1 Dissertação tese final 1.pdf: 2637411 bytes, checksum: a84a13ce10364272026f9558f59c65df (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-11-23T12:35:19Z (GMT) No. of bitstreams: 1 recco_lc_me_bot.pdf: 2637411 bytes, checksum: a84a13ce10364272026f9558f59c65df (MD5) / Made available in DSpace on 2016-11-23T12:35:20Z (GMT). No. of bitstreams: 1 recco_lc_me_bot.pdf: 2637411 bytes, checksum: a84a13ce10364272026f9558f59c65df (MD5) Previous issue date: 2016-09-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho foram estudadas síntese e caracterização de filmes finos híbrido de polímeros escovas constituídos de polieletrolíticos reforçados com nanotubos de carbono sobre o substrato de óxido de índio e estanho (ITO). Para a caracterização das superfícies dos filmes foram utilizadas as técnicas de microscopia eletrônica de varredura (MEV), energia dispersiva de raio-x (EDX) e espectroscopia Raman. Foram avaliadas diferentes propriedades estímulo-responsivas dos polímeros escovas que levam a modificações estruturais dos filmes como a influência de pH e da força iônica. Os polímeros escolhidos como modelos foram os polímeros Poli (Vinil Imidazol)-(PVI) e Poli (Àcido Acrilíco)-(PAA). Os ensaios eletroquímicos evidenciaram uma dependência da conformação dos polímeros escovas com a variação de pH e da força iônica e também revelaram o aumento da capacitância desses polímeros quando reforçados com os nanotubos de carbono, sendo que, o PVI obteve melhor resposta quando exposto a pH ácido, uma vez que suas cadeias poliméricas estavam estendidas e carregadas positivamente, permitindo a difusão da espécie redox carregada negativamente até a superfície do eletrodo. O PAA também obteve melhor resposta em meio ácido. Nesse caso as cadeias colapsadas aproximam os tubos do transdutor (ITO), facilitando a troca do par redox. Após a caracterização dos referidos polímeros, os mesmos foram testados como sensores para o monitoramento de hormônios e neurotransmissores que desempenham funções importantes no nosso organismo. / This study describes the synthesis and characterization of hybrid polyelectrolyte based on polymer brush reinforced multi-layer type carbon nanotubes. The characterization of the thin films we used the scanning electron microscopy techniques (SEM), energy dispersive x-ray (EDX) and Raman spectroscopy . The influence of pH and ionic strength were evaluated by electrochemical technique. The polymers Poly (vinyl imidazole) - (PVI) and poly (acrylic acid) - (PAA) were used as matrix brush for anchoring the nanotubes. Electrochemical tests showed a dependence of the conformation of the brush polymers with pH change and ionic strength, and also showed the increase in capacitance of these polymers when reinforced with carbon nanotubes, and the PVI obtained a better response when exposed to acidic pH since its polymer chains were extended and positively charged, allowing the diffusion of negatively charged redox species to the electrode surface. The PAA also obtained better response in acid. In this case the collapsed chains near the transducer tubes (ITO) facilitate the electrons transference. The made electrodes were applied to monitor hormones and neurotransmitters that play important functions in our body.

Aterros sanitários são a forma mais viável de disposição final dos resíduos sólidos urbanos no Brasil, tanto do ponto de vista técnico quanto econômico. Os antigos lixões estão sendo progressivamente substituídos por aterros bem projetados e operados. Entretanto, os aterros ainda representam risco ambiental devido à liberação de gases e produção de lixiviado (chorume). Os gases podem ser canalizados e queimados ou usados para produção de energia. O tratamento do lixiviado, porém, ainda representa um desafio aos profissionais da área, não tendo ainda sido encontrada uma solução eficaz. As próprias características físico-químicas deste efluente não são bem conhecidas. No presente trabalho buscou-se contribuir para a solução do problema mediante estudos em três frentes: a caracterização detalhada do lixiviado de aterros brasileiros, o estudo da remoção da amônia (o principal poluente presente no lixiviado) por arraste com ar e a importância da força iônica. A compilação de dados referentes a 40 aterros, distribuídos em todas as regiões do país, possibilitou a elaboração de tabelas com as características típicas do lixiviado durante as fases ácida e metanogênica dos aterros. Não se apresentou apenas os valores extremos de cada variável, mas também as faixas mais prováveis de variação. Também foi possível concluir que a fase ácida na maior parte dos casos não dura mais que dois anos nos aterros brasileiros, desde que esses sejam dotados de sistemas de drenagem de base. O estudo do arraste de amônia foi efetuado em torres de 15 cm de diâmetro e 1 m de altura útil, usando-se anéis de polietileno corrugado como material de recheio. Os resultados mostraram que torres aeradas permitem a remoção praticamente total do nitrogênio amoniacal, independentemente de se fazer ou não alcalinização prévia do lixiviado. O volume de ar necessário para remover uma determinada massa de amônia é sempre constante. Somente foi observada nitrificação quando as concentrações de nitrogênio amoniacal ficaram abaixo de 50 mg/L. A elevada força iônica do lixiviado pode ser a responsável pelo fraco desempenho do processo de coagulação-floculação quando aplicado a este efluente. A força iônica é um aspecto pouco estudado no âmbito da engenharia sanitária e ambiental, mas que não pode ser desconsiderada nos estudos acerca do lixiviado. Outros aspectos foram investigados, como o efeito do cloreto na DQO (demanda química de oxigênio) e a possibilidade de desenvolvimento de larvas de insetos nas lagoas de lixiviado. / Sanitary landfills are considered as the most appropriate way for final disposal of municipal solid wastes in Brazil, in the technical and economical point of view. Open dumps have been progressively substituted by well engineered and operated landfills. However, landfills still present environmental risks due to the gas emission and leachate production. Gases can be piped and burnt or used to the electricity production, but the same can not be applied to the leachate. Moreover, the leachate treatment still represents a challenge to the expertise of the area because it was not already found an efficient solution for it. The physical-chemical characteristics of this effluent are not well known yet. This research sought to contribute to the solution of this problem by focusing in three main lines: detailed characterization of the leachate of Brazilian landfills, investigation of the possibilities of ammonia removal (the main pollutant present in the leachate) by air stripping process and evaluation of the importance of the ionic strength. The compilation of data from 40 sanitary landfills, distributed in all the geographic regions of Brazil, allowed the preparation of tables describing the typical characteristics of Brazilian leachates during the acid and methanogenic phases. It was presented not only the extreme values, but also the most probable ranges of variation. It was also possible to conclude that the acid phase lasts no more than 2 years in Brazilian landfills equipped with adequate leachate drainage systems. The study of ammonia air stripping was carried out in towers of 15 cm of diameter and 1 m of packed bed height. Corrugated plastic Raschig rings were used as packing media. Results showed that the aerated towers were able to remove the ammonia almost completely, independently if the pH of leachate was previously increased or not. The volume of air necessary to remove a determined mass of ammonia is always constant. Nitrification occurred only when total ammonia nitrogen concentrations were lower than 50 mg/L. This led to the conclusion that biological systems should not be applied directly to the treatment of raw methanogenic leachate. The high ionic strength of the leachate can be the responsible for the low efficiencies of coagulation-flocculation process applied to this effluent. Even though ionic strength is not usually considered by sanitary and environmental engineering, it should be considered in the studies dealing with leachate. Other aspects were also investigated, as the effect of the chloride in COD (chemical oxygen demand) measurements and the possibility of maggots growth in leachate ponds.

Carbon –based engineered nanoparticles have been widely used due to their small size and uniquephysical and chemical properties. They can dissolve in water, transport through soil and reach drinkingwater resources. The toxic effect of engineered nanoparticles on human and fish cells has beenobserved; therefore, their release and distribution into the environment is a subject of concern. In thisstudy, two types of engineered nanoparticles, multi-walled carbon nano-tubes (MWCNT) and C60 withcylindrical and spherical shapes, respectively, were used. The aim of this study was to investigatetransport and retention of carbon-based engineered and natural nanoparticles through saturated porousmedia. Several laboratory experiments were conducted to observe transport behavior of thenanoparticles through a column packed with sand as a representative porous media. The columnexperiments were intended to monitor the effect of ionic strength, input concentration and the effect ofparticle shape on transport. The results were then interpreted using Derjaguin-Landau-Verwey-Overbeak (DLVO) theory based on the sum of attractive and repulsive forces which exist betweennanoparticles and the porous medium. It was observed that as the ionic strength increased from 1.34mM to 60 mM, the mobility of the nanoparticles was reduced. However, at ionic strength lower than10.89 mM, mobility of C60 was slightly higher than that of MWCNTs. At ionic strength of 60 mMMWCNT particles were significantly more mobile. It is rather difficult to relate this difference to theshape of particle and further studies are required.The effect of input concentration on transport of MWCNTs and C60 was observed in bothmobility of the particle and shape of breakthrough curves while input concentration was elevated from7 mg/l to 100 mg/l. A site-blocking mechanism was suggested to be responsible for the steep andasymmetric shape of the breakthrough curves at the high input concentration.Furthermore inverse modeling was used to calculate parameters such as attachment efficiency,the longitudinal dispersivity, and capacity of the solid phase for the removal of particles. The inversionprocess was performed in a way that the misfit between the observed and simulated breakthroughcurves was minimized. The simulated results were in good agreement with the observed data.

Abstract Electrostatic interactions are very important in biomolecular systems. Electrostatic forces have received a great deal of attention due to their long-range nature and the trade-off between desolvation and interaction effects. It remains a challenging task to study and to predict the effects of electrostatic interactions in biomolecular systems. Computer simulation techniques that account for such interactions are an important tool for the study of biomolecular electrostatics. This study is largely concerned with the role of electrostatic interactions in biomolecular systems and with developing novel models to estimate the strength of such interactions. First, a novel formulation based upon continuum electrostatics to compute the electrostatic potential in and around two biomolecules in a solvent with ionic strength is presented. Many, if not all, current methods rely on the (non)linear Poisson-Boltzmann equation to include ionic strength. The present formulation, however, describes ionic strength through the inclusion of explicit ions, which considerably extends its applicability and validity range. The method relies on the boundary element method (BEM) and results in two very similar coupled integral equations valid on the dielectric boundaries of two molecules, respectively. This method can be employed to estimate the total electrostatic energy of two protein molecules at a given distance and orientation in an electrolyte solution with zero to moderately high ionic strength. Secondly, to be able to study interactions between biomolecules and membranes, an alternative model partly based upon the analytical continuum electrostatics (ACE) method has been also formulated. It is desirable to develop a method for calculating the total solvation free energy that includes both electrostatic and non-polar energies. The difference between this model and other continuum methods is that instead of determining the electrostatic potential, the total electrostatic energy of the system is calculated by integrating the energy density of the electrostatic field. This novel approach is employed for the calculation of the total solvation free energy of a system consisting of two solutes, one of which could be an infinite slab representing a membrane surface.

This diploma thesis deals with acid-base and electrolytic behavior of hyaluronan solutions at different ionic strength. Acid-base behavior of hyaluronan was investigated by acid-base titrations which were carried out with two different methods, acid and alkaline acid-base titration. Dissociation constants at different ionic strength at zero degree of dissociation and at 50% degree of dissociation were evaluated from the results of acid-base titrations. Dissociation constants obtained from acid acid-base titrations have values between 3,0 and 3,6. Dissociation constants obtained from alkaline acid-base titrations are not very informative because their values are much higher than the expected values. The study of degradation of hyaluronan during acid-base titration was performed to complete study of acid-base behavior. Electrolytic behavior of hyaluronan solution was performed by conductometric titrations in three different environments.

The report summarizes the results obtained by the Institute of Resource Ecology of the Helmholtz-Zentrum Dresden-Rossendorf within the BMWi-financed Joint Research Project “Geochemical retention of radionuclides on cement alteration phases (GRaZ)”. The project focused on the retention behavior of Ca-bentonite and cementitious material, both constituents of the geo-engineered barrier of deep geological repositories for high-level radioactive waste, towards radionuclides. Specifically, the influence of increased salinities and of hyperalkaline conditions on interaction processes in the system radionuclides – organics – clay/cementitious materials – aquifer was studied. For this purpose, complexation, sorption and desorption studies were performed at alkaline to hyperalkaline pH conditions (pH 8-13) and under variation of the ionic strength (0.1 to 4 M) applying complex solution compositions. For the U(VI) citrate system molecular structures dominating in the pH range 2-9 were studied spectroscopically (NMR, UV-Vis, FT-IR). As dominating species 2:2, 3:3, 3:2 and, above critical concentrations also 6:6 and 9:6 U(VI) citrate complexes were identified or confirmed and complex formation constants were determined. U(VI) sorption on Ca-bentonite at (hyper)alkaline conditions in mixed electrolyte solutions was studied by means of batch sorption experiments. The U(VI) retention on Ca-bentonite was shown to be very effective at pH>10, even in the presence of carbonate and despite the prevalence of anionic aqueous uranyl species. The presence of two independent U(VI) surface complexes on Ca-bentonite at pH 8-13 was shown by site-selective TRLFS and EXAFS spectroscopy. The sorption of anionic uranyl hydroxide complexes to the mineral surface was shown to be mediated by calcium cations. In further experiments, the effect of isosaccharinic acid (ISA) and polycarboxylate ether (PCE) on U(VI) and Eu(III) sorption, respectively, on Ca-bentonite was studied. An effect of ISA on U(VI) sorption on Ca-bentonite only occurs when ISA is present in very high excess to U(VI). The effect of PCE, as a commercial cement superplasticizer, on Eu(III) sorption onto Ca-bentonite was negligible already at moderate ionic strengths. The retention of U(VI) and Cm(III) by various C-(A-)S-H phases, representing different alteration stages of concrete, was studied by batch sorption experiments. Sorbed or incorporated actinide species were identified by TRLFS. The stability of U(VI) and Cm(III) doped C-(A-)S-H phases at high ionic strengths conditions was studied in solutions simulating the contact with North German claystone formation water. Potential changes of actinide speciation as well as formation of secondary phases due to leaching effects were followed spectroscopically. The results of this project show that both bentonite and cementitious material constitute an important retention barrier for actinides under hyperalkaline conditions and increased ionic strength.