Afin d'améliorer la compréhension de la corrosion atmosphérique des bronzes, nous avons mis en oeuvre : - La caractérisation des composés d'étain, susceptibles d'être formés en corrosion atmosphérique, par une approche multi-analytique, la spectroscopie Mössbauer joue un rôle central (analyse sélective et quantitative). Les paramètres hyperfins et les facteurs Lamb-Mössbauer de plusieurs oxydes, sulfates et chlorures d'étain ont été déterminés. Les facteurs f sont dispersés et dépendants de température, montrant la nécessité de l'analyse à basse température. - Le développement d'un détecteur CEMS associant basse température et analyse non-destructive de surface : le dispositif a été mis en point entre 41 et 300 K. Les principaux paramètres affectant ses performances ont été étudiés et optimisés. - La réalisation d'une campagne d'exposition de 2 ans en site urbain de CuSn9, CuSn3Zn9, CuZn33 et leurs métaux purs. Les vitesses de corrosion ont été déterminées ainsi que les quantités de métaux entraînés par les eaux de pluie du fait de la solubilisation des produits de corrosion.

Open-framework inorganic materials constitute an important area of study in materials chemistry, because of their potential applications in areas such as sorption and catalysis. After the discovery of nanoporous aluminium phosphates (AlPOs) by Flanigen et al in 1982, there has been a tremendous growth in the area of porous solids that are based on phosphates. Apart from phosphates, phosphites, arsenates, sulfates, sulfites, selenates, selenites etc. have also been investigated. In addition to the different anions, the framework compounds now encompass almost all the elements of the periodic table. The compounds exhibit wide variety and structural diversity. New building units, such as thiosulfate and borate have also been explored as a network builder in the formation of framework structures. In this thesis, the results of the investigations on open-framework metal thiosulfates, metal borates and metal sulfates are presented. The studies are aimed not only at the synthesis of the new compounds based on the new anions, but also their possible applications. In Chapter 1 of the thesis an overview of inorganic open-framework materials with different anions is presented. In Chapter 2 (Part A), the synthesis, structure and transformation of inorganic-organic hybrid open-framework cadmium thiosulfate are presented. The lack of stability of the thiosulfate ion in solution prompted the exploration of new approaches such as low temperature solvothermal methods, use of rigid linkers etc. The transformations of lower to higher dimensional structures have been accomplished. The possible mechanisms for such transformations were investigated. In Part B, the physical and chemical properties of the hybrid cadmium thiosulfate frameworks are presented. The studies indicate that the anionic dyes selectively adsorb on the compounds in the water medium and also desorb reasonably in alcoholic medium. The cadmium thiosulfate compounds appear to be reasonable photocalysts for the photodecomposition of the cationic dyes under UV irradiation as well as under sunlight with good recyclability. The compounds also exhibit heterogeneous catalytic behavior (Lewis acidity) for the cyanosilylation of the imines. In Chapter 3, a new family of organically templated open-framework borate materials is presented. The zinc and aluminoborate structures, prepared in the present study, are rationalized using the HSAB theory. The [B4O9H2] units polymerize differently to form different zinc borate structures. The amine molecules act as a ligand by binding with the metal. The nature of the amine appears to control the dimensionality of the final zinc borate structures. The zinc borate compounds exhibit absorption of UV-light (λ = 365 nm) suggesting that the zinc borate compounds could be exploited for UV-blocking applications. Organically templated aluminoborates have connectivities between the Al3+ ions and the [B5O10] cyclic pentaborate units. The aluminoborate structures exhibit graphite layer and three-dimensional diamond structure. Detailed studies and comparison of the various amine templated open-framework aluminoborate structures reveals subtle relationships between the organic amines (shape and length of the amines) and the final framework structures. In Chapter 3, the synthesis, structure and catalytic studies of a variety of cadmium sulfate phases have been carried out. Polyazaheterocyclic ligands were employed to study their possible role in the formation of such structures. All the compounds have structures built up by the connectivity involving the cadmium octahedra and the sulfate tetrahedra in which the heterocyclic organic molecules act as the ligand. The connectivity between the Cd2+ and (SO4)2− ions form one-, two-and three-dimensionally extended cadmium sulfate phases, though the starting source is cadmium sulfate (CdSO4.8/3H2O) in all the cases. The connectivity between Cd2+ ion and the heterocyclic ligand also gives rise to one-and two-dimensional structures. The interconnectivity between the two units gives rise to the final observed structure. As part of the study, a variety of properties i.e. adsorption-desorption, photocatalytic degradation and cyanosilylation reaction, exhibited by the cadmium sulfate compounds have been investigated and the properties are comparable to the cadmium thiosulfate phases. AlPOs are well known for their many important properties. The wide varieties in their structures and heterogeneous catalytic properties have been extensively investigated. The photocatalytic behaviors, on the contrary, have not been investigated in detail. The photocatalytic properties of the metal-doped AlPOs, for the photodegrdation of organic dyes have been investigated in the Chapter 5. The metal ions (Mg2+, Zn2+ and Co2+) have been substituted in place of Al3+ and Ti4+ in place of both the Al3+ and P5+ in a variety in AlPO structures and the synthesized phases are characterized by a variety of techniques. Photodecomposition studies of organic dye molecules under UV-light were carried out in aqueous medium. The studies suggest that the photocatalytic activity is reasonable and appears to depend on the dopant concentration. Ti-substituted phase exhibits the maximum catalytic activity.

Les homéoprotéines sont des facteurs de transcription importants au cours du développement des organismes vivants, capables notamment de voyager de cellule en cellule. Ces protéines comportent une longue extrémité N-terminale désordonnée, suivie de trois hélices α séparées par une boucle et un tour. Des études de relations structure-activité ont montré que des domaines cationiques (riches en K et R) particuliers dans ces protéines sont responsables de ces propriétés de transfert cellulaire leur permettant d’être secrétées et internalisées dans les cellules. Ces processus impliquent que ces protéines hydrophiles soient capables de franchir la membrane plasmique composée d'un coeur hydrophobe. La membrane plasmique est en effet composée d’une bicouche lipidique, dans laquelle sont insérées de nombreuses protéines, telles que les protéoglycanes portant des ramifications de glycosaminoglycanes (GAG), polysaccharides anioniques. Dans le but de comprendre au niveau moléculaire le processus d'entrée des homéoprotéines dans des cellules eucaryotes, différentes constructions protéiques ont été produites et étudiées : le peptide pénétrant les cellules correspondant à l'hélice 3 (H3), la séquence correspondant à l'homéodomaine (HD), l'homéodomaine étendu d'une séquence putative de liaison aux GAG (NLS-HD) et la protéine entière (En2). La quantification absolue de l’entrée de ces constructions dans des cellules CHO-K1 par spectrométrie de masse a mis en évidence une efficacité d'entrée meilleure pour H3 > NLS-HD > HD, ainsi que l’importance des GAG de surface dans le processus et plus particulièrement celui des héparanes sulfates (HS). Des expériences complémentaires d’ITC, de dichroïsme circulaire et de RMN ont permis d'identifier deux sites d’interaction avec l’héparine (un site principal de haute affinité et un site secondaire de plus basse affinité), interagissant principalement avec le polysaccharide par interactions électrostatiques. In fine, ces études conduisent à une meilleure compréhension moléculaire du processus d'internalisation des homéoprotéines dans des cellules eucaryotes. / Homeoproteins are important transcription factors during the development of living organisms, and are able to travel from cell to cell. These proteins contain a long N-terminal extremity structurally disordered, followed by three α helices separated by a U-turn. Structure-activity relation studies have shown that in these proteins, some cationic domains (rich in K and R) confer them the cellular transfer properties, allowing them to be secreted by and internalized into cells. These processes imply that the hydrophilic proteins are able to cross plasma membrane. Indeed, the plasma membrane possess a hydrophobic heart and is composed by a lipidic bilayer, in which numerous proteins are inserted, such as proteoglycans carrying glycosaminoglycan (GAG) ramifications, that belong to anionic polysaccharids. In order to understand the entry process of homeoproteins into eukaryotic cells at a molecular level, different proteic constructions have been produced and studied: the cell penetrating peptide corresponding to the third α helix (H3), the sequence corresponding to its homeodomain (HD), the homeodomain with an added putative GAG-binding domain (NLS-HD), and the wild-type protein Engrailed 2 (En2). The absolute mass spectrometry quantification of the peptide and proteins in cells shows a range of internalization efficiency as follows: H3 > NLS - HD > HD. It also highlights the importance of cell-surface GAGs in the internalization and more particularly that of heparan sulfates (HS). Complementary experiments of ITC, circular dichroism and NMR have shown two interaction sites for the heparin (one principal site of high affinity and a secondary site showing a lower affinity) both interacting mainly with polysaccharidic residues using electrostatic interactions. In fine, these studies lead to a better molecular understanding of homeoproteins internalization process in eukaryotic cells.

Submitted by Mery Piedad Zamudio Igami (mery@ipen.br) on 2017-03-10T14:37:28Z No. of bitstreams: 1 22056.pdf: 6258956 bytes, checksum: 5b6bd2c4bc8c6f66cd739d2ef10fe810 (MD5) / Made available in DSpace on 2017-03-10T14:37:28Z (GMT). No. of bitstreams: 1 22056.pdf: 6258956 bytes, checksum: 5b6bd2c4bc8c6f66cd739d2ef10fe810 (MD5) / A soldagem por fricção (Friction Stir Welding - FSW) é um processo eficiente de unir ligas de alumínio de alta resistência evitando defeitos que são usualmente criados quando técnicas convencionais de soldagem são utilizadas. A indústria aeronáutica tem mostrado grande interesse neste método de soldagem, tanto para a união de ligas similares como dissimilares. Entretanto, este processo causa modificações microestruturais dependentes das condições de tratamento térmico ou termomecânico. Contato elétrico entre zonas de microestruturas diferentes, por sua vez, pode resultar em acoplamento galvânico. No presente estudo, a soldagem por FSW foi usada para unir duas ligas de alumínio dissimilares, AA2024-T3 e AA7475-T651 e o efeito desta soldagem na resistência à corrosão das juntas soldadas e na microestrutura das ligas foi avaliada. Na investigação da resistência à corrosão foram utilizados ensaios eletroquímicos, especificamente, medidas de potencial de circuito aberto (OCP) em função do tempo de exposição ao meio corrosivo, ensaios de polarização e de espectroscopia de impedância eletroquímica, global (EIS) ou local (LEIS), em duas soluções, seja 0,1 M Na2SO4 ou 0,1 M Na2SO4 + 1 mM NaCl. Os ensaios eletroquímicos evidenciaram efeito de acoplamento galvânico nas juntas soldadas. A caracterização microestrutural foi realizada por microscopia ótica, microscopia eletrônica de varredura, microscopia eletrônica de transmissão e por calorimetria diferencial. As zonas afetadas pela solda tiveram importantes modificações na microestrutura indicadas pela precipitação e dissolução de precipitados que afetam a resistência à corrosão localizada. A resistência à corrosão intergranular e a resistência à esfoliação das juntas soldadas também foram avaliadas e comparadas com as das ligas AA2024-T3 e AA7475-T651 não soldadas. Os resultados mostraram aumento da suscetibilidade das juntas soldadas a estas formas de corrosão em comparação com as ligas não soldadas sendo observado ataque mais severo na liga AA7475-T651. A identificação das áreas anódicas e catódicas resultantes do acoplamento galvânico nas juntas soldadas foi realizada por teste que consistiu na deposição de camada de gel (ágar-ágar) com indicador universal na superfície das ligas soldadas. A liga AA2024-T3 atuou como cátodo, enquanto a AA7475-T651, como ânodo no par galvânico. Além disso, evolução de hidrogênio foi observada na região de interface entre a zona termomecanicamente afetada e a termicamente afetada da liga AA7475-T651 mostrando que reações catódicas também ocorreram localmente nesta última liga. Resultados de LEIS obtidos nas diferentes zonas das duas ligas soldadas por FSW mostraram acoplamento galvânico na interface entre elas para tempos curtos de ensaio e deslocamento da região mais ativa com o tempo de ensaio para a liga AA7475-T651, mais precisamente para a interface entre a zona termomecanicamente afetada e a térmicamente afetada desta liga. / Tese (Doutorado em Tecnologia Nuclear ) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Le soufre est présent dans les systèmes pétroliers à la fois sous forme organique et minérale. Il est impliqué dans de nombreuses réactions d'oxydoréduction qui affectent la qualité des huiles (par des réactions de sulfuration ou de désulfuration) et du gaz naturel (par la génération de H2S en contexte de réduction thermochimique des sulfates), ainsi que la porosité des roches réservoirs (par la dissolution de l'anhydrite ou la précipitation de soufre élémentaire ou de pyrobitume). Ces réactions sont gouvernées par la température (et dans une moindre mesure la pression), les conditions d'oxydoréduction et la composition chimique globale du système. La thèse comporte trois parties : (1) une étude thermodynamique des réactions chimiques impliquant le soufre dans les bassins sédimentaires ; (2) une étude expérimentale des réactions de sulfuration et de désulfuration des composés organiques ainsi que de la réduction thermochimique des sulfates; (3) une étude pétrographique et d'inclusions fluides sur des échantillons d'un réservoir carbonaté du bassin Pré-Caspien / Sulfur occurs in petroleum systems as both organic compounds and minerals as well as under different oxidation states. It is involved in a number of redox reactions which may impact the quality of crude oils (through sulfurization or desulfurization reactions) and natural gas (through the generation of H2S during thermochemical sulfate reduction), as well as the petrophysical properties of reservoir rocks (through the dissolution of anhydrite and the precipitation of elemental sulfur and pyrobitumen). These reactions are controlled by temperature (and to a lesser extent pressure), the redox conditions, and the overall chemical composition of the system representing the petroleum reservoir. The thesis consists of three parts: (1) a thermodynamic study of chemical reactions involving sulfur which occur in sedimentary basins; (2) an experimental simulation of sulfurization and desulfurization reactions of organic compounds, as well as of thermochemical sulfate reduction; and (3) a petrographic and fluid inclusion study of carbonate rock samples from a sulfur-rich hydrocarbon reservoir of the northern Caspian Sea

El deterioro de las estructuras de concreto debido al ataque de agentes externos, es una de las problemáticas con más énfasis en el rubro de la construcción, ya que afecta directamente las propiedades de la infraestructura, dando como resultado la reducción de vida útil. Por otro lado, tenemos el incremento de construcciones cerca al litoral marítimo, sin embargo, surge la problemática de presencia de eflorescencia, desprendimiento, corrosión o manchas en el concreto, por el ataque de sulfatos presente en el agua de mar, en el suelo, y en la humedad. A lo largo de los años se ha propuestos productos como adiciones en la composición del cemento o productos no permeables para aplicar al concreto, con el fin de minimizar el impacto. Para la presente investigación se estudia la efectividad del polvo de ladrillo, como reemplazo parcial del cemento, mediante los ensayos de resistencia a la compresión, trabajabilidad en estado fresco, volumen de contenido de vacíos y permeabilidad. Se realizó pruebas con cuatro diferentes proporciones de reemplazo como es 5%, 15%, 25% y 30%, para una resistencia de f´c 300 kg/cm2. De acuerdo a los resultados, se concluyó que la muestra con reemplazo parcial de polvo de ladrillo de arcilla en 25%, demuestran resultados óptimos como mayor resistencia, además de un bajo volumen de contenido de vacíos y una permeabilidad baja. Asimismo, muestra una reducción económica de fabricación por m3 de 8.72%, en comparación a la muestra convencional. / The deterioration of concrete structures due to the attack of external agents, is one of the problems with more emphasis in the construction sector, since it directly affects the properties of the infrastructure, resulting in a reduction in useful life. On the other hand, we have the increase in constructions close to the sea coast, however, the problem of efflorescence, detachment, corrosion or stains on the concrete arises, due to the attack of sulphates present in seawater, in the soil, and in the humidity. Over the years, products such as additions in the cement composition or non-permeable products have been proposed to apply to concrete, in order to minimize the impact. For the present investigation, the effectiveness of brick dust is studied as a partial replacement for cement, through tests of compressive strength, workability in a fresh state, void content volume and permeability. Tests were carried out with four different replacement proportions such as 5%, 15%, 25% and 30%, for a resistance of f'c 300 kg / cm2. According to the results, it was concluded that the samples with partial replacement of clay brick dust in 25% demonstrate optimal results such as greater resistance, in addition to a low volume of voids content and a low permeability. Likewise, it shows an economic reduction in manufacturing of m3 of 8.72%, compared to the conventional sample. / Tesis

Soil aquifer treatment was simulated in 1 m laboratory soil columns containing silica sand under saturated and unsaturated soil conditions to examine the effect of travel length through the unsaturated zone on the removal of wastewater organic matter, the effect of soil type on dissolved organic carbon removal and also the type of microorganisms involved in the removal process. Dissolved organic carbon removal and nitrification did enhance when the wastewater travelled a longer length through the unsaturated zone. A similar consortium of microorganisms was found to exist in both saturated and unsaturated columns. Microbial concentrations however were lowest in the soil column containing silt and clay in addition to silica sand. The presence of silt and clay was detrimental to DOC removal efficiency under saturated soil conditions due to their negative effect on the hydraulic performance of the soil column and microbial growth.

Álcoois primários sulfatados de cadeia longa, usualmente na forma de sais de sódio, são tensoativos de grande interesse comercial utilizados em diversas formulações de higiene pessoal e limpeza doméstica. Eles são produzidos comercialmente através da reação de álcoois etoxilados com trióxido de enxofre seguida de imediata neutralização com hidróxido de sódio. O produto formado é uma solução neutra de álcool primário etoxilado sulfatado em água. Sabe-se que a armazenagem desse produto por longos períodos de tempo em temperaturas elevadas pode levar à hidrólise completa, mas, em condições normais de uso e temperatura ambiente é esperado que o produto seja resistente à hidrólise. No entanto observou-se que algumas amostras comerciais de lauril éter sulfato de sódio que foram estocadas por diferentes períodos de tempo em frascos fechados à temperatura ambiente sofreram hidrólise em intervalos de tempo relativamente curtos. Isso leva à hipótese de que o comportamento de hidrólise seria influenciado por outras variáveis além da temperatura e do tempo de estocagem. O presente trabalho consistiu em identificar as variáveis de maior impacto na reação de hidrólise por meio de experimentos planejados. O teor de ativos foi acompanhado ao longo da reação para avaliar o efeito da presença de eletrólitos, de material insulfatado, em diferentes temperaturas, variando-se o pH inicial por meio da adição de ácido clorídrico. O comportamento da reação de hidrólise observado foi compatível com aquele descrito na literatura para o dodecil sulfato de sódio. A hidrólise apresentou-se como sendo autocatalítica, com a aceleração da taxa de reação provavelmente causada pela presença de íons hidrogênio liberados na reação. Foi possível identificar que as variáveis de maior efeito na reação foram: pH inicial, o teor de cloreto de sódio e a temperatura. O modelo de troca iônica em pseudo-fase foi utilizado para o tratamento dos resultados experimentais e mostrou-se adequado tendo sido, portanto, utilizado para prever o comportamento de estabilidade do produto à temperatura ambiente e nas condições em que o produto é normalmente comercializado. Um modelo empírico de redes neurais foi desenvolvido com sucesso para prever o comportamento do pH ao longo do tempo para as condições estudadas. / Long-chain primary alkyl sulfuric acids, usually as their sodium salts, are important commercial surfactants used in a large number of household and personal care formulations. They are commercially produced by treatment of mixtures of ethoxylated fatty alcohols with sulfur trioxide followed by immediate neutralization with sodium hydroxide, a neutral aqueous mixture of sodium primary alkyl ether sulfate is obtained. It is known that prolonged storage of the material at elevated temperature can lead to complete hydrolysis but under normal use and typical environmental conditions the product is expected to be resistant to hydrolysis. In spite of that it has been observed that some commercial samples of sodium lauryl ether sulfate stored for different periods of time in sealed containers at room temperature have undergone hydrolysis in a relatively short period of time which leads to the hypothesis that the hydrolysis behavior would be strongly influenced by variables other than temperature and storage time. The present work consisted of identifying the process variables with the most significant effect on the acid hydrolysis by using experimental design. The rate of hydrolysis has been followed acidimetrically to evaluate the effect of electrolytes as well as the concentration of unsulfated matter at different temperatures, over a wide initial pH range, under the presence of added hydrochloric acid. The pattern of kinetic behaviour observed was broadly the same as previously described for the sodium dodecyl sulfate. The hydrolysis presented the characteristic autocatalytic form, the catalysis presumably arising from the production of hydrogen sulfate ions. It was possible to observe that the most significant effects on the rate of hydrolysis were the initial pH, the total amount of sodium chloride and the temperature. The results were also discussed in terms of the ion-exchange pseudophase model of the micelle reaction. Accordingly to the fitting of parameters that was carried out it is possible to conclude that the pseudo-phase ion-exchange theory is found to account satisfactorily for the results reported and it was used to predict the stability behavior of the product at room temperature and under normal commercial conditions. A neural network based model was also successfully developed in order to predict the pH behavior in the conditions studied.

Thesis (M.S.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).

Álcoois primários sulfatados de cadeia longa, usualmente na forma de sais de sódio, são tensoativos de grande interesse comercial utilizados em diversas formulações de higiene pessoal e limpeza doméstica. Eles são produzidos comercialmente através da reação de álcoois etoxilados com trióxido de enxofre seguida de imediata neutralização com hidróxido de sódio. O produto formado é uma solução neutra de álcool primário etoxilado sulfatado em água. Sabe-se que a armazenagem desse produto por longos períodos de tempo em temperaturas elevadas pode levar à hidrólise completa, mas, em condições normais de uso e temperatura ambiente é esperado que o produto seja resistente à hidrólise. No entanto observou-se que algumas amostras comerciais de lauril éter sulfato de sódio que foram estocadas por diferentes períodos de tempo em frascos fechados à temperatura ambiente sofreram hidrólise em intervalos de tempo relativamente curtos. Isso leva à hipótese de que o comportamento de hidrólise seria influenciado por outras variáveis além da temperatura e do tempo de estocagem. O presente trabalho consistiu em identificar as variáveis de maior impacto na reação de hidrólise por meio de experimentos planejados. O teor de ativos foi acompanhado ao longo da reação para avaliar o efeito da presença de eletrólitos, de material insulfatado, em diferentes temperaturas, variando-se o pH inicial por meio da adição de ácido clorídrico. O comportamento da reação de hidrólise observado foi compatível com aquele descrito na literatura para o dodecil sulfato de sódio. A hidrólise apresentou-se como sendo autocatalítica, com a aceleração da taxa de reação provavelmente causada pela presença de íons hidrogênio liberados na reação. Foi possível identificar que as variáveis de maior efeito na reação foram: pH inicial, o teor de cloreto de sódio e a temperatura. O modelo de troca iônica em pseudo-fase foi utilizado para o tratamento dos resultados experimentais e mostrou-se adequado tendo sido, portanto, utilizado para prever o comportamento de estabilidade do produto à temperatura ambiente e nas condições em que o produto é normalmente comercializado. Um modelo empírico de redes neurais foi desenvolvido com sucesso para prever o comportamento do pH ao longo do tempo para as condições estudadas. / Long-chain primary alkyl sulfuric acids, usually as their sodium salts, are important commercial surfactants used in a large number of household and personal care formulations. They are commercially produced by treatment of mixtures of ethoxylated fatty alcohols with sulfur trioxide followed by immediate neutralization with sodium hydroxide, a neutral aqueous mixture of sodium primary alkyl ether sulfate is obtained. It is known that prolonged storage of the material at elevated temperature can lead to complete hydrolysis but under normal use and typical environmental conditions the product is expected to be resistant to hydrolysis. In spite of that it has been observed that some commercial samples of sodium lauryl ether sulfate stored for different periods of time in sealed containers at room temperature have undergone hydrolysis in a relatively short period of time which leads to the hypothesis that the hydrolysis behavior would be strongly influenced by variables other than temperature and storage time. The present work consisted of identifying the process variables with the most significant effect on the acid hydrolysis by using experimental design. The rate of hydrolysis has been followed acidimetrically to evaluate the effect of electrolytes as well as the concentration of unsulfated matter at different temperatures, over a wide initial pH range, under the presence of added hydrochloric acid. The pattern of kinetic behaviour observed was broadly the same as previously described for the sodium dodecyl sulfate. The hydrolysis presented the characteristic autocatalytic form, the catalysis presumably arising from the production of hydrogen sulfate ions. It was possible to observe that the most significant effects on the rate of hydrolysis were the initial pH, the total amount of sodium chloride and the temperature. The results were also discussed in terms of the ion-exchange pseudophase model of the micelle reaction. Accordingly to the fitting of parameters that was carried out it is possible to conclude that the pseudo-phase ion-exchange theory is found to account satisfactorily for the results reported and it was used to predict the stability behavior of the product at room temperature and under normal commercial conditions. A neural network based model was also successfully developed in order to predict the pH behavior in the conditions studied.