Oxidation of aqueous bromide into reactive, gas-phase bromine species has been of interest since the 1980’s, when the presence of bromine in the Arctic boundary layer was linked to ozone depletion events. We have investigated two different mechanisms for Br2 release from sea ice. We have shown that nitrate in sea ice can photolyze to produce OH, which can go on to form gas-phase Br2. This reaction is analogous to a known reaction that occurs in the aqueous phase. We have also investigated Br2 production from a heterogeneous reaction between gas-phase ozone and sea ice/seawater. We have determined ozone’s reactive uptake coefficient, and have shown how it varies with temperature, bromide concentration, ozone concentration and acidity. We have been able to decouple the bulk aqueous chemistry that occurs from the Langmuir-Hinshelwood surface chemistry, and quantify the relative contribution of each.

Oxidation of aqueous bromide into reactive, gas-phase bromine species has been of interest since the 1980’s, when the presence of bromine in the Arctic boundary layer was linked to ozone depletion events. We have investigated two different mechanisms for Br2 release from sea ice. We have shown that nitrate in sea ice can photolyze to produce OH, which can go on to form gas-phase Br2. This reaction is analogous to a known reaction that occurs in the aqueous phase. We have also investigated Br2 production from a heterogeneous reaction between gas-phase ozone and sea ice/seawater. We have determined ozone’s reactive uptake coefficient, and have shown how it varies with temperature, bromide concentration, ozone concentration and acidity. We have been able to decouple the bulk aqueous chemistry that occurs from the Langmuir-Hinshelwood surface chemistry, and quantify the relative contribution of each.

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-02T18:48:59Z No. of bitstreams: 1 ManuelFarias.pdf: 1389622 bytes, checksum: 6e4849f2b44871723791cde342c7bf04 (MD5) / Made available in DSpace on 2017-06-02T18:48:59Z (GMT). No. of bitstreams: 1 ManuelFarias.pdf: 1389622 bytes, checksum: 6e4849f2b44871723791cde342c7bf04 (MD5) Previous issue date: 2006-06-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / This is work treat of the acetaldehyde and labeled ethanol oxidations, both kinds in percloric acidic medium, 0,1 Mol L-1 HClO4 on the Pt polycrystalline surface with used conventional electrochemical and spectroscopy techniques (FTIRS in situ). From acetaldehyde, wanted to find the mean concentration that better favor the reaction to evolve for CO2 in the potential smaller from production of the kind. The concentration 0,01 Mol L-1 was better suitable, but the increase of the concentration in solution, this is pathway was whole inhibited. However, in the high potential the form to acetic acidic is favorable. For main cronoamperometry, acetaldehyde in the concentration 0,02 Mol L-1, were able proof results in situ FTIRS. According to potential, this is results was interpreted second pattern to consider: the pear adsorbed kinds (Langmuir-Hinshelwood) and other where consider only one adsorbed kinds between adsorbed (pattern Eley-Rideal mechanism). In the case of ethanol labeled oxidation (H3 13CO 12CH2OH), it is search to look into the path delineated from way severous of the reaction from to form CO2. The results showed that is product would to be results of the intermediates oxidations contained carbon from alcohol group and intermediates contained carbon from group methyl; however, the intermediates contained carbon alcohol group is mores able reactive in the zone potential searched in the work, is this mores, confronted with able reactive metil group. The path double that yield CO2 in the zone potential below 1,0 V, are yielded coupling bands 12COL and 13COL which coexist in below potential. In the presence kind 13COL in 0,4 V potential proof that of the efficiency of the platinum electrode for the oxygenation group metil in the zone below potential. In the potential largest that 1,0 V, where exist the formation continuous of carbon dioxide, the difference in the greatness bands associated from 12CO2 e 13CO2 (double path product contained carbon), was interpreted in the sense of the electrochemical conditions infortunable for remover hydrogen group metil; additional this is kind was to promote for yield from molecules, which not is able identify for whole technique. / Este trabalho trata das reações de eletrooxidações de acetaldeído comum e etanol isotopicamente marcado, ambas reações em superfície de platina policristalina em meio de ácido perclórico, HClO4, 0,1 Mol L-1, com a utilização de técnicas eletroquímicas convencionais e espectroscopia (FTIRS in situ). Para o acetaldeído, essa reação foi estuda com a dependência do potencial aplicado e a concentração do aldeído em solução, que melhor resultaram na transformação desta molécula a CO2. Assim, para o potencial 0,6 V, a concentração de aldeído 0,01 Mol L-1 foi a mais apropriada deduzida a partir de FTIRS in situ e, a concentração 0,02 Mol L-1 permitiu a geração de maior densidade de corrente e foi inferida a partir de cronoamperometria. Essa discrepância foi discutida em termos das reações específicas que resultam no sinal analítico para cada técnica. Dependendo da concentração do acetaldeído, a via de formação de CO2 foi completamente inibida e, em altos potenciais, prevalecia sempre a formação de ácido acético. Paralelamente, dependendo do potencial, estes resultados foram interpretados com base em modelos de mecanismos de reações que considera: um par de reagentes adsorvidos (mecanismo Langmuir-Hinshelwood) e apenas uma espécie adsorvida do par fundamental de reagentes (mecanismo Eley-Rideal). Para o etanol isotopicamente marcado (H3 13C 12CH2OH), foram investigados passos delineados pelas diferentes vias de reação de formação de CO2. Os resultados mostraram que este produto pode ser resultante da eletrooxidação de intermediários contendo o carbono do grupo álcool e do grupo metil, sendo que o intermediário contendo o carbono do grupo álcool, para toda a faixa de potenciais investigados, é bem mais reativo que o intermediário contendo o carbono do grupo metil. As vias duplas que geram CO2 em potenciais abaixo de 1,0 V são resultantes de bandas acopladas de 12COL e 13COL que coexistem em baixos potenciais. A presença de 13COL em 0,35 V foi encarada como uma evidência da eficiência da Pt para oxigenação do grupo metil em baixos potenciais. Em potenciais acima de 1,0 V, onde há produção contínua de dióxido de carbono, a diferença na magnitude das intensidades de bandas relativa ao 13CO2 e 12CO2 (das vias de origem de carbono), foi interpretada como sendo as referidas condições eletroquímicas desfavoráveis para desprotonação do metil.

In dieser Arbeit wurden Gold- und PlatinNanopartikel in sphärischen Polyelektolyt-Bürsten (SPB) synthetisiert. Diese wurden zu mechanistischen Untersuchungen der p-Nitrophenol-Reduktion mittels Natriumborhydrid herangezogen. Dabei konnte der Mechanismus der Reaktion auf der Oberfläche der Nanopartikel aufgeklärt werden. Die Reaktion folgt einem Langmuir Hinshelwood (LH) Mechanismus. Hierbei adsorbieren beide Edukte auf die Oberfläche, bevor sie im zu p-Aminophenol umgesetzt werden. Nach der Reaktion desorbiert das Reaktionsprodukt. Mittels des LH Modells konnten für verschiedene Temperaturen die intrinsische Geschwindigkeitskonstante, sowie die Adsorptionskonstanten der Edukte bestimmt werden. Mit diesen Daten konnten dann die Enthalpie und Entropie der Adsorption der Edukte und die Aktivierungsenergie berechnet werden. Neben dem Reaktionsmechanismus wurde die Induktionszeit der p-Nitrophenol Reduktion untersucht. Hierbei konnte gezeigt werden, dass diese Totzeit der Reaktion wahrscheinlich auf eine Restrukturierung der Nanopartikeloberfläche zurückzuführen ist. Sie ist unabhängig von den eingesetzten Konzentrationen des Borhydrids, hingegen abhängig von der Konzentration an p-Nitrophenol auf der Oberfläche der Nanopartikel, was auf Restrukturierung der Nanopartikel durch p-Nitrophenol hindeutet. Zudem wurden Hinweise auf eine spontane Rekonstruktion der Nanopartikel gefunden, die unabhängig von der Konzentration des p-Nitrophenols ist. Des Weiteren wurde die katalytische Oxidation von Morin mit Manganoxid Nanopartikeln untersucht. Diese sind in der Polyelektrolytschale der SPB immobilisiert. Analysen der Reaktionskinetik der Morin Oxidation ergaben, dass auch in diesem Fall der LH Mechanismus vorliegt. Hierbei konnten die Adsorptionskonstanten und Geschwindigkeitskonstanten für verschiedene Temperaturen ermittelt werden und somit die Aktivierungsenergie der Oxidation sowie die Adsorptionsenthalpie und Entropie der Edukte. / In this work, gold and platinum nanoparticles were synthesized into spherical polyelectrolyte brushes (SPB) in order to apply them as catalysts for kinetic studies of the reduction of p-nitrophenol by sodium borohydride. It was found that the reaction follows the Langmuir-Hinshelwood (LH) mechanism where both educts must adsorb onto the surface of the catalyst in order to react. Thereby, the rate determining step is the surface reaction of both educts. After the reaction, the product desorbs from the surface and a free active site is formed. With this model the intrinsic reaction rate and the adsorption constants for both educts could be determined. The measurements at different temperatures allowed the calculation of the activation energy and the adsorption enthalpy and entropy of the educts. Besides the reaction mechanism, the induction time of the reaction was analyzed. Here, it was shown that the reason of this delay time is a restructuring of the nanoparticle surface. The induction time is solely dependent on the concentration of p-nitrophenol on the surface of the nanoparticles and independent of the applied concentrations of borohydride. Moreover, hints for a spontaneous reconstruction of the nanoparticles without p-nitrophenol were found. In the second part, the catalytic oxidation of morin by manganese oxide has been studied. These nanoparticles were embedded inside the polyelectrolyte layer of the SPB. These nanoparticles were used for systematic studies of the oxidation of morin with hydrogen peroxide. It was shown that in this case the reaction followed a LH kinetics as well. Here, the intrinsic rate constants and the adsorption constants could be obtained for different temperatures. The activation energy and the adsorption enthalpy and entropy could be determined accordingly. The adsorption enthalpy is exothermic in both cases.

Tese de Programa Doutoral. Engenharia Química e Biológica. Universidade do Porto. Faculdade de Engenharia. 2012

Dans le milieu interstellaire (MIS), la formation de la molécule H_2 est catalysée par un grain de poussière : H+H+grain -> grain+ H_2 Deux mécanismes principaux correspondent à cette réaction: le mécanisme Eley-Rideal (ER) et le mécanisme Langmuir-Hinshelwood (LH). Les techniques de propagation de paquets d'ondes ont été utilisées pour étudier ces deux mécanismes aux faibles températures qui règnent dans le MIS. Pour rendre possible le calcul, il a fallu utiliser une grille en L et appliquer la technique de réduction de grille dite de « mapping » sur des grilles multidimensionnelles. Ceci a permis de couvrir une gamme d'énergie de collision comprise entre 0,4meV et 46meV pour le mécanisme ER, et entre 4meV et 50meV pour le mécanisme LH. Le mécanisme ER a été étudié en géométrie colinéaire sur une surface de graphite (0001), en autorisant le mouvement d'un atome de carbone du grain. Permettre cette relaxation du substrat favorise la réaction. Toutefois le mécanisme ER reste peu efficace dans les conditions de température régnant dans le MIS, du fait d'une petite bosse de potentiel en voie d'entrée. Le mécanisme LH a lui été étudié dans toute sa dimensionnalité sur une surface plane et rigide. Le résultat principal est que ce mécanisme est très efficace : dans des conditions caractéristiques du MIS, le temps mis par un atome H pour diffuser sur le grain, rencontrer un autre atome H, et désorber en H2 est inférieur au temps typique entre deux collisions H-grain. La réaction n'a aucun effet notable sur le rapport ortho- H_2 et para- H_2. En revanche, comme dans le mécanisme ER, elle conduit à une très forte excitation vibrationnelle de H_2.

In dieser Arbeit wurden zwei katalytische Modellreaktionen studiert. Zunächst die katalytische Reduktion von p-Nitrophenol (Nip) mit Natriumborhydrid (BH_4^-). Diese verläuft entlang der direkten Route: Dabei wird Nip über p-Hydroxylaminophenol (Hx) zum Produkt p-Aminophenol (Amp) reduziert. Ein kinetisches Modell wird vorgestellt, dass die Reaktion auf Basis des Langmuir-Hinshelwood (LH) Mechanismus beschreibt. Die Lösung der Gleichungen gibt die Nip Konzentration als Funktion der Zeit, welche direkt mit den experimentellen Daten verglichen werden kann. Werden als Katalysator auf sphärischen Polyeletrolytbürsten stabilisierte Gold Nanopartikel (SPB-Au) verwendet, zeigt sich eine gute Übereinstimmung und unterstreicht die Allgemeingültigkeit der direkten Route. Der zweite Teil beschäftigt sich mit der katalytischen Oxidation von 3,3’,5,5’-Tetramethylbenzidin (TMB) durch Wasserstoffperoxid (H_2O_2) an SPB-Pt Nanopartikeln. Dabei wurden die Katalyse mithilfe zweier Modelle analysiert: Michaelis-Menten (MM) und Langmuir-Hinshelwood (LH). Im MM Modell wird die Oxidation von TMB durch die Nanopartikel mit der Peroxidase katalysierten TMB Oxidation unter Annahme des Ping-Pong Mechanismus verglichen. Es wurde gezeigt, dass die häufig verwendete Analyse der initialen Reaktionsraten große Fehler verursacht und zu inkonsistenten Ergebnissen führt. Dies zeigt dass dieses Vorgehen zu Analyse der Oxidation von TMB nicht geeignet ist. Im LH Modell wird angenommen dass H_2O_2 und TMB im ersten Schritt auf der Oberfläche der Nanopartikel adsorbieren. Das LH Modell mit Produktinhibition ermöglicht hierbei eine zufriedenstellende Beschreibung der kinetischen Daten bis zu einem Umsatz von 40 %. Die gesamte Analyse zeigt, dass das Langmuir-Hinshelwood Modell die bessere Näherung zur Beschreibung der Kinetik der Nanopartikel katalysierten TMB Oxidation bietet / In this work, two catalytic model reactions were studied using different metallic nanoparticles in aqueous solution. One is the catalytic reduction of p-nitrophenol (Nip) by sodium borohydride (BH_4^-). The reaction proceeds in the following route: Nip is first reduced to p-hydroxylaminophenol (Hx) which is further reduced to the final product p-aminophenol (Amp). Here we present a full kinetic scheme according to Langmuir-Hinshelwood mechanism (LH). The solution of the kinetic equations gives the concentration of Nip as the function of time, which can be directly compared with the experimental data. Satisfactory agreement is found for reactions catalyzed by Au nanoparticles immobilized in spherical polyelectrolyte brushes (SPB-Au) verifying the validity of the reaction route. In the second part, we present a study on the catalytic oxidation of 3,3’,5,5’-tetramethylbenzidine (TMB) by hydrogen peroxide (H_2O_2) with SPB-Pt nanoparticles. The catalysis was analyzed by two different models: Michaelis-Menten (MM) and Langmuir-Hinshelwood (LH) model. In the MM model, the oxidation of TMB catalyzed by nanoparticles is inferred to the catalysis of peroxidase assuming the Ping-Pong mechanism. It is found that the frequently used analysis with the initial rates introduces large errors and leads to inconsistent results, which indicates that such approach is not suitable to analyze the oxidation of TMB catalyzed by nanoparticles. In the LH model, it is assumed that H_2O_2 and TMB adsorb on the surface of nanoparticles in the first step. The LH model with product inhibition gives satisfactory description of the kinetic data up to a conversion of 40%. The entire analysis demonstrates that the Langmuir-Hinshelwood model provides a superior approach to describe the kinetics of TMB oxidation catalyzed by nanoparticles.

Le contexte environnemental (réchauffement climatique) et économique (épuisement des ressources en énergies fossiles) entraîne une nécessaire mutation du paysage énergétique mondial. L’hydrogène est présenté comme un vecteur d’énergie propre pouvant, par l’intermédiaire d’une pile à combustible, fournir de l’électricité pour diverses applications (nomade, portable, automobile et stationnaire). Cependant, son développement reste tributaire de son mode de stockage. Parmi les composés présentant de bonnes capacités de stockage, le borohydrure de sodium NaBH4 se distingue puisqu’il permet aussi un dégagement contrôlé de l’hydrogène d’après la réaction d’hydrolyse suivante : ( ) (2 ) ( ) ( ) 4 ( ) 4 2 2 2 2 NaBH ++ x H O l→NaBO . xH O + H g Il constitue ainsi une solution sûre et facile d’utilisation, et est donc envisageable pour des applications grand public. La thèse avait pour objectif l’approfondissement des connaissances relatives à la réaction catalysée d’hydrolyse du borohydrure de sodium selon deux axes principaux: la catalyse de la réaction et l’étude des produits d’hydrolyse. Concernant le premier axe, notre objectif était de mieux comprendre et d’améliorer la cinétique de la réaction d’hydrolyse, les catalyseurs étudiés étant à base de cobalt. Un catalyseur « modèle » a été utilisé et comparé à des nanoparticules métalliques synthétisées et d’autres espèces chimiques à base de cobalt (oxyde, hydroxyle et carbonate). Le modèle cinétique de Langmuir-Hinshelwood a permis de décrire la cinétique de l’hydrolyse. Un mécanisme réactionnel basé sur les adsorptions en surface du catalyseur de BH4 - et de H2O a été proposé. Enfin, la nature des sites actifs en surface a été discutée. En ce qui concerne le second axe de la thèse, nous avions deux objectifs : identifier les phases formées en fonction des conditions expérimentales et approfondir les connaissances thermodynamiques du système binaire NaBO2-H2O pour définir les différents équilibres se formant à l’issu de la réaction d’hydrolyse. Pour ce faire, les borates ont d’abord été synthétisés, puis caractérisés en termes de structure cristallographique et de stabilité en température. C’est ainsi qu’un nouveau borate de sodium, Na3[B3O4(OH)4] ou NaBO2•2/3H2O, a été obtenu. D’autre part, l’étude des équilibres liquide+solide, solide+solide et liquide+vapeur nous a permis d’établir le diagramme binaire NaBO2-H2O à pression atmosphérique. / As an alternative solution to fossil fuels, hydrogen is may be the most advanced technology. However, its large scale development is today harshly hindered by the issues it encounters, its storage being certainly the most significant. Various storage methods are under investigation but solid storage as in sodium borohydride NaBH4 appears to be convenient with regard to its storage capacities, safety and cost. The hydrogen stored in NaBH4 can be released by hydrolysis at ambient temperature. The hydrolysis reaction leads to the formation of 4 hydrogen molecules and borates: ( ) (2 ) ( ) ( ) 4 ( ) 4 2 2 2 2 NaBH ++ x H O l → NaBO . xH O + H gThe efficiency of this reaction suffers from two problems. First, slow kinetics of hydrogen release is observed for this reaction. Second, the “hydration” of NaBO2 is detrimental to the storage capacities of the system NaBH4-H2O. Indeed, the higher the pseudo-hydration degree (i.e. x), the lower the gravimetric hydrogen storage capacity. Both issues are the topics we have studied in the present work. Hydrogen release can be accelerated by using a cobalt catalyst. Hence, we focused on various cobalt-based catalysts. A reference catalyst was first chosen, and then tested and compared to lab-prepared cobalt nanoparticles and other cobalt-based materials (oxide, hydroxide and carbonate). The Langmuir-Hinshelwood kinetic model well captured the kinetics of the hydrolysis reaction. Accordingly, a reaction mechanism based on the adsorptions of both BH4 - and H2O on the catalyst surface has been proposed. The adsorptions are expected to occur on specific surface sites which nature has been discussed. The gravimetric hydrogen storage capacity of NaBH4-H2O can be increased by decreasing the pseudo-hydration degree (i.e. x) of the borates. However, this implies that the thermodynamics of the NaBO2•xH2O compounds are well known as they are crucial for favouring the formation of water-free borates. Borates were then synthesized and characterized in terms of crystallographic structure, pseudo-hydration degree and thermal stability. In this context, a new sodium borate has been synthesized: Na3[B3O4(OH)4] or NaBO2•2/3H2O. Besides, we studied the liquid+solid, liquid+vapor and solid+solid equilibria that permitted to set the binary phase diagram NaBO2-H2O at atmospheric pressure

Ethyl lactate (EL) plays a major role as green solvent and also a replacement for most petrochemical solvents. The esterification process of lactic acid and ethanol to produce EL is an equilibrium-limiting reaction and the selective removal of one of the reaction products can be improved using a membrane reactor and when coupled with a heterogeneous catalyst offers an opportunity for process intensification. This thesis investigates the batch process esterification reaction involving lactic acid (LA) and ethanol (EL) in the presence of a water selective membrane using different cation-exchange resin catalysts. The product was analysed using gas chromatograph coupled with mass spectrometry detector (GC-MS). The analytical methods used for the characterisation of the cation-exchange resins and membrane include Fourier transform infrared coupled with attenuated total reflectance (FTIR-ATR), scanning electron microscopy attached to energy dispersive analyser (SEM/EDAX), Liquid nitrogen physisorption and nuclear magnetic resonance (NMR) respectively. A novel method was developed for carrying out esterification reaction in a gaseous phase system using a flat sheet polymeric membrane. Prior to the esterification reaction, different carrier gases were tested with ceramic membrane to determine the suitable carrier gases for the analysis of esterification product. The four carrier gases used for the permeation test were argon (Ar), helium (He), carbon dioxide (CO2) and nitrogen (N2). A 15nm pore size commercially available tubular ceramic support, consisting of 77%Al2O3 and 23%TiO2 with the porosity of 45% was used for the carrier gas investigation. The support was modified with silica based on the sol-gel dip-coating techniques. The dip-coated membrane exhibited a higher molar flux with He (0.046mol m-2s-1) and Ar (0.037mol m-2s-1) with a much lower flux for N2 (0.037mol m-2s-1) and CO2 (0.035 mol m-2s-1) at 0.30 bar. Helium gas with the highest permeation rate were identified as the suitable carrier gas for the analysis of esterification product with GC-MS. The esterification reaction in the presence of four cation-exchange resins to produce ethyl lactate was carried out between 60-160 oC in a batch and membrane processes to determine the effectiveness resin catalysts for LA esterification. The effect of external mass transfer diffusion limitation between the liquid components and the resin catalysts was avoided by increasing the agitation time of the esterification reaction. The percentage conversion rate of the lactic acid feed from the batch process esterification was found to be in the range of 98.6 to 99.8%. The reaction kinetics of the esterification reaction was described based on two simplified mechanisms of Langmuir Hinshelwood model to describe the adsorption components on the surface of the catalysts. The lactic acid feed gave a conversion rate of up to 100 % confirming the effectiveness of the acetate membrane impregnated resin catalysts in the selective removal of water for the separation of ethyl lactate. The significance of producing ethyl lactate through batch process intensified by a water-selective membrane processes can be recommended for industrial LA production.

Le contexte environnemental (réchauffement climatique) et économique (épuisement des ressources en énergies fossiles) entraîne une nécessaire mutation du paysage énergétique mondial. L'hydrogène est présenté comme un vecteur d'énergie propre pouvant, par l'intermédiaire d'une pile à combustible, fournir de l'électricité pour diverses applications (nomade, portable, automobile et stationnaire). Cependant, son développement reste tributaire de son mode de stockage. Parmi les composés présentant de bonnes capacités de stockage, le borohydrure de sodium NaBH4 se distingue puisqu'il permet aussi un dégagement contrôlé de l'hydrogène d'après la réaction d'hydrolyse suivante : ( ) (2 ) ( ) ( ) 4 ( ) 4 2 2 2 2 NaBH ++ x H O l→NaBO . xH O + H g Il constitue ainsi une solution sûre et facile d'utilisation, et est donc envisageable pour des applications grand public. La thèse avait pour objectif l'approfondissement des connaissances relatives à la réaction catalysée d'hydrolyse du borohydrure de sodium selon deux axes principaux: la catalyse de la réaction et l'étude des produits d'hydrolyse. Concernant le premier axe, notre objectif était de mieux comprendre et d'améliorer la cinétique de la réaction d'hydrolyse, les catalyseurs étudiés étant à base de cobalt. Un catalyseur " modèle " a été utilisé et comparé à des nanoparticules métalliques synthétisées et d'autres espèces chimiques à base de cobalt (oxyde, hydroxyle et carbonate). Le modèle cinétique de Langmuir-Hinshelwood a permis de décrire la cinétique de l'hydrolyse. Un mécanisme réactionnel basé sur les adsorptions en surface du catalyseur de BH4 - et de H2O a été proposé. Enfin, la nature des sites actifs en surface a été discutée. En ce qui concerne le second axe de la thèse, nous avions deux objectifs : identifier les phases formées en fonction des conditions expérimentales et approfondir les connaissances thermodynamiques du système binaire NaBO2-H2O pour définir les différents équilibres se formant à l'issu de la réaction d'hydrolyse. Pour ce faire, les borates ont d'abord été synthétisés, puis caractérisés en termes de structure cristallographique et de stabilité en température. C'est ainsi qu'un nouveau borate de sodium, Na3[B3O4(OH)4] ou NaBO2*2/3H2O, a été obtenu. D'autre part, l'étude des équilibres liquide+solide, solide+solide et liquide+vapeur nous a permis d'établir le diagramme binaire NaBO2-H2O à pression atmosphérique.