O estudo do fenômeno de expansão em solos argilosos tem-se restringido, na maioria das vezes, a estudos laboratoriais referentes ao comportamento mecânico do solo e as correlações com as propriedades índices e as classificações geotécnicas. Poucos são os estudos na área de mapeamento geotécnico em média e grande escala, existindo um vazio nas metodologias de mapeamento geotécnico no que se refere a esta classe de solos. Durante o desenvolvimento desta pesquisa sobre as características expansivas da Fm. Libertad, Quaternário (Uruguai), foram combinados os produtos obtidos das técnicas de mapeamento com os propriedades identificadas nos ensaios de caracterização e as medidas de expansão. A técnica de avaliação de terreno usando Landforms para separar unidades homogêneas, resultou em um grande auxílio permitindo direcionar os trabalhos e observações de campo e diminuir o numero de amostras a serem coletadas. O ensaio de caracterização da Capacidade de Troca Catiônica (CTC) da fração argila, usando a técnica de Azul de Metileno, mostrou-se coincidente com a identificação de argilo-minerais usando Difração de Raios X (DRX). Esses dados, associados aos valores de Pressão de Expansão e Expansão livre de amostra indeformadas, com umidade natural e secas ao ar, e de amostras compactadas com diferentes massas específicas seca (pd) e umidade constante (w=15%) permitiram identificar unidades com diferentes potenciais de expansão na Fm. Libertad. A combinação desses dados permitiu a produção da Carta de Potencial de Expansão do Solos, numa região de desenvolvimento urbano no Município de Montevidéu, Uruguai. Este documento fornece aos planejadores do uso e ocupação da área o conhecimento dos diferentes graus de restrição que devem ser levados em conta devido à presença de solos potencialmente expansivos. Elaborou-se uma proposta metodológica para a execução de trabalhos de mapeamento geotécnico de solos expansivos. / The swelling phenomenon of the clay soils has been studied mainly in laboratory with the objective of undestand the behavior of the soil and the correlations with the index properties and with the geotechnical classifications. In Engineering Geotechnical Mapping there is a lack of methodology about swell soil mapping in medium or large scale. In this research the swelling characteristics of the Libertad Formation (Uruguay) were studied by combination of the information obtained in the Engineering Geotechnical Mapping (scale 1:10.000) and the soil properties identified in the characterization and swelling tests. The technique of land evaluation using Landforms to separate homogeneous units, it resulted in a great aid allowing to guide the works and field observations and to reduce the number of samples to be collected. The characterization tests of cationic exchange capacity (CEC) of the clay, using the technique of adsorption of methilene blue, it was shown coincident with the identification of clay using X-Ray Diffraction (XRD). The swelling potentials of the Libertad Formation were determined based in the information of the values of swelling pressure and free swelling from undisturbed samples, both with natural moisture contents and air dried, besides the samples compacted with different apparent specific gravity (pd) and with constant moisture content (w= 15%). This procedure allowed the production of the Swelling Potential Chart of the soil in an suburban area of Montevideo City, Uruguay. This document can supply the information to the management of the area taken in account the different swelling potential of the soils. Finally it is presented a methodology to carry out Engineering Geological Mapping of the swelling soils.

O estudo do fenômeno de expansão em solos argilosos tem-se restringido, na maioria das vezes, a estudos laboratoriais referentes ao comportamento mecânico do solo e as correlações com as propriedades índices e as classificações geotécnicas. Poucos são os estudos na área de mapeamento geotécnico em média e grande escala, existindo um vazio nas metodologias de mapeamento geotécnico no que se refere a esta classe de solos. Durante o desenvolvimento desta pesquisa sobre as características expansivas da Fm. Libertad, Quaternário (Uruguai), foram combinados os produtos obtidos das técnicas de mapeamento com os propriedades identificadas nos ensaios de caracterização e as medidas de expansão. A técnica de avaliação de terreno usando Landforms para separar unidades homogêneas, resultou em um grande auxílio permitindo direcionar os trabalhos e observações de campo e diminuir o numero de amostras a serem coletadas. O ensaio de caracterização da Capacidade de Troca Catiônica (CTC) da fração argila, usando a técnica de Azul de Metileno, mostrou-se coincidente com a identificação de argilo-minerais usando Difração de Raios X (DRX). Esses dados, associados aos valores de Pressão de Expansão e Expansão livre de amostra indeformadas, com umidade natural e secas ao ar, e de amostras compactadas com diferentes massas específicas seca (pd) e umidade constante (w=15%) permitiram identificar unidades com diferentes potenciais de expansão na Fm. Libertad. A combinação desses dados permitiu a produção da Carta de Potencial de Expansão do Solos, numa região de desenvolvimento urbano no Município de Montevidéu, Uruguai. Este documento fornece aos planejadores do uso e ocupação da área o conhecimento dos diferentes graus de restrição que devem ser levados em conta devido à presença de solos potencialmente expansivos. Elaborou-se uma proposta metodológica para a execução de trabalhos de mapeamento geotécnico de solos expansivos. / The swelling phenomenon of the clay soils has been studied mainly in laboratory with the objective of undestand the behavior of the soil and the correlations with the index properties and with the geotechnical classifications. In Engineering Geotechnical Mapping there is a lack of methodology about swell soil mapping in medium or large scale. In this research the swelling characteristics of the Libertad Formation (Uruguay) were studied by combination of the information obtained in the Engineering Geotechnical Mapping (scale 1:10.000) and the soil properties identified in the characterization and swelling tests. The technique of land evaluation using Landforms to separate homogeneous units, it resulted in a great aid allowing to guide the works and field observations and to reduce the number of samples to be collected. The characterization tests of cationic exchange capacity (CEC) of the clay, using the technique of adsorption of methilene blue, it was shown coincident with the identification of clay using X-Ray Diffraction (XRD). The swelling potentials of the Libertad Formation were determined based in the information of the values of swelling pressure and free swelling from undisturbed samples, both with natural moisture contents and air dried, besides the samples compacted with different apparent specific gravity (pd) and with constant moisture content (w= 15%). This procedure allowed the production of the Swelling Potential Chart of the soil in an suburban area of Montevideo City, Uruguay. This document can supply the information to the management of the area taken in account the different swelling potential of the soils. Finally it is presented a methodology to carry out Engineering Geological Mapping of the swelling soils.

Expansive soils contain clay minerals that undergo a change in bulk volume in response to variances in environmental conditions. The ability to predict the occurrence and geotechnical behavior of swelling soils with a known degree of certitude would allow engineers to take measures to limit the damage resulting from these metastable soils. Research was conducted to investigate the regional distribution, mineralogy, and engineering properties of expansive soils in the Tucson Basin. Mineralogic studies employed X-ray diffraction procedures for the identification of clay mineralogy. The compilation of expansion-related soil parameters, from the geotechnical job-files of a local engineering consulting firm, allowed the development of an engineering database. The application of geostatistical analysis for the cartographical representation of mineralogic and geotechnical data permitted a regional characterization of expansive clay soils. Clay mineralogy was found to be directly related to the volumetric stability displayed by native soils, as well as the geology of the Tucson Basin.

Alkali compounds were added to a South African coal with a high swelling propensity and the behaviour of the blends were investigated. A vitrinite-rich bituminous coal from the Tshikondeni coal mine in the Limpopo province of South Africa was used. To reduce the influence of the minerals in the coal, the coal was partially demineralized by leaching with HCl and HF. The ash content of the coal sample was successfully reduced from 17.7% to 0.6%. KOH, KCl, K2CO3 and KCH3CO2 were then added to the demineralized coal in mass percentages of 1%, 4%, 5% and 10%. The free swelling indices (FSI) of the blends were determined and the samples were subjected to acquisition of TMA and TG-MS data. Addition of these potassium compounds to the demineralized coal reduced the swelling of the vitrinite-rich coal. From the free swelling indices of the various mixtures, it was concluded that the potassium compounds reduce the swelling of the coal in the following order of decreasing impact: KCH3CO2 > KOH > K2CO3 > KCl. From dilatometry experiments done on the blends with the 10% addition of potassium compounds, it was seen that with the addition of potassium compounds to the demineralized coal, a reduction in dilatation volume was obtained. The influence of the potassium compound in decreasing order: K2CO3> KOH> KCH3CO2> KCl. An increase in the softening temperature was observed for the demineralized coal-alkali blends. Thermogravimetric analyses were performed on the demineralized coal-potassium blended samples (<75 μm). These samples were pyrolyzed under a nitrogen atmosphere to a maximum temperature of 1200 °C using a heating rate of 10 °C/min. The relative reactivity for each of the blends with the different wt% addition was determined. From these results it was seen that KCH3CO2 increased the relative reactivity, whereas the KOH, KCl and K2CO3 showed an inhibiting influence. The attached mass spectrometer provided information on the low molecular mass gaseous products formed in the various temperature ranges as the thermal treatment proceeded. From the mass spectroscopy results, it was found that the potassium compounds decreased the temperature at which maximum evolution of H2 takes place. Thermomechanical analyses were performed on the 10 wt% addition of the potassium compounds to the demineralized coal. During TMA analyses, the sample was heated to 1000 °C using a heating rate of 10 °C/min. From the TMA result obtained it was clear that the addition of KCl did not have an influence on the swelling of the demineralized coal. All results are discussed. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

The swelling-activated chloride current, commonly referred to as ICl,swell, is an outwardly-rectifying anion current that plays an important role in cell volume regulation, among other capacities. Despite several decades of research, the molecular identity of the channel responsible for this chloride current remains controversial. Recent indications that key endogenous sulfhydryl groups are capable of modifying the current led us to assess the effects of several divalent cations, including zinc, on ICl,swell. Zinc is known to tightly associate with sulfhydryl groups such as in zinc finger proteins. We found that extracellular zinc irreversibly inhibited ICl,swell at a site downstream in the signaling cascade. Moreover, zinc blocking kinetics were voltage dependent, suggesting interaction with a site within the electric field, across the pore of the channel responsible for ICl,swell. The importance of sulfhydryl groups was confirmed by demonstrating irreversible block by N-ethylmaleimide, a sulfhydryl alkylating reagent. In contrast, nickel failed to block ICl,swell, and as noted in previous studies, cadmium preferentially blocked the time-dependent component of ICl,swell. These data confirm the importance of sulfhydryl groups in the function of ICl,swell. Moreover, by demonstrating the voltage-dependence of block, the data strongly suggest the critical sulfhydryl group is within the channel pore. These biophysical characteristics of native ICl,swell are markers that should be recapitulated in expressed proteins claimed to be responsible for ICl,swell.

Le stockage géologique du carbone dans les veines de charbon est une solution transitoire pour lutter contre le réchauffement climatique. La faisabilité de ce stockage à un coût abordable reste incertaine, en particulier parce que l'injection de dioxide de carbone dans les veines de charbon est lente. Les projets pilotes ont montré que la perméabilité du réservoir diminue lors de l'injection, suite au gonflement du charbon induit par l'adsorption préférentielle du dioxyde de carbone par rapport au méthane présent naturellement. Ce mémoire de thèse est consacré à l'étude de ce gonflement. Un premier travail théorique a consisté à étendre les équations constitutives de poromécanique classique dans les cas où l'adsorption sur des surfaces ou dans des micropores devient significative. Nous avons montré que le comportement poromécanique du solide ne peut être compris que si la dépendance de l'adsorption en fonction de la déformation du milieu poreux est connue. Le couplage entre adsorption et déformation est peu étudié dans la littérature et difficile à mesurer expérimentalement. Dans ce travail, nous avons utilisé la simulation moléculaire qui permet facilement de contrôler indépendamment la pression du fluide adsorbé et la déformation du milieu poreux. A l'aide de simulations moléculaires d'adsorption dans des systèmes modèles unidimensionnels, nous avons validé les nouvelles équations consitutives. Nous avons montré également que l'adsorption peut dépendre de la déformation de façon complexe et qu'elle est très sensible à la structure des micropores. Les résultats de simulations moléculaires d'adsorption dans un modèle moléculaire réaliste de la matrice organique du charbon nous ont permis de montrer que le gonflement du charbon en présence de fluide peut être expliqué par l'adsorption dans les micropores, mais pas dans les mésopores. Nous avons étudié numériquement le couplage entre adsorption et déformation dans le charbon. Le gonflement estimé en associant les simulations moléculaires d'adsorption aux nouvelles équations constitutives de poromécaniques est en bon accord avec les mesures expérimentales. De même, nous avons simulé l'adsorption de mélanges de dioxide de carbone et de méthane dans le charbon à des températures et pressions représentatives des conditions souterraines. Le résultat de ces simulations a permis d'estimer le gonflement différentiel durant l'injection de carbone pour des veines de charbon à différentes profondeurs. / Pas de résumé en anglais

La complexité des mécanismes de transport en nanofiltration (NF) nécessite ledéveloppement d’outils de modélisation fiables permettant de comprendre et d’optimiser lesopérations de séparation en NF.La présente étude comprend deux volets. Le premier porte sur la rétention d’un soluténeutre – le poly(éthylène glycol) à 600 g mol-1 (PEG) – seul et en présence d’ions, par unemembrane organique de NF (polyamide). Les résultats obtenus montrent que la rétention dusoluté neutre chute en présence d’ions et ce, d’autant plus que la concentration du sel estélevée. Ce phénomène ne peut être expliqué par le seul phénomène de déshydratation dusoluté neutre par les ions environnants. Un phénomène supplémentaire de gonflement de porea été mis en évidence et corrélé à la densité de charge membranaire. La contribution des deuxphénomènes à la chute du taux de rejet du PEG a été évaluée pour différents sels à plusieursconcentrations.Le deuxième volet du travail est consacré à (i) l’évaluation de la constante diélectrique desolutions à l’intérieur de nanopores (ep) d’une membrane organique de NF (polyamide) àpartir de mesures de potentiel de membrane et (ii) la validation de cette méthode. Les valeursobtenues s’avèrent être inférieures à celle de la solution externe (effet du confinement) etdiminuer avec l’augmentation de la proportion en ions calcium du mélange (effet structurantdes ions). L’accord entre les constantes diélectriques ep déterminées à partir de mesures depotentiel de membrane et de taux de rejet ionique (mélanges ternaires) valide la cohérence dumodèle de transport utilisé (exclusion stérique, électrique et diélectrique aux interfaces) etmontre que les mesures de potentiel de membrane peuvent être envisagées pour l’évaluationcorrecte de la constante diélectrique à l’intérieur de nanopores / The complexity of transport mechanisms in nanofiltration (NF) requires the developmentof reliable modelling tools for understanding and optimizing the separation process.This study is composed of two parts. The first one focuses on the retention of a neutralsolute – poly(ethylene glycol) 600 g mol-1 (PEG) – in single solute solutions and in thepresence of mineral salts by an organic NF membrane (polyamide). Results show that PEGrejection is significantly lower in mixed-solute solutions and that rejection rate drop increaseswith salt concentration. This phenomenon cannot be imputed to only the partial dehydrationof PEG molecules by surrounding ions (salting-out effect). The additional hypothesis whichwas considered in the present work is an increase in the effective pore size (pore swelling).This hypothesis was supported by electrokinetics charge density data. The contribution ofpore swelling and salting-out to the overall decrease in the rejection rate of PEG wasevaluated for different salts at various concentrations.The second part of this study deals with (i) the determination of the dielectric constantinside pores (ep) of an NF organic membrane from membrane potential measurements and (ii)the validation of this technique. Membrane potential data were analyzed by means of theSEDE (steric, electric and dielectric exclusion) transport model. ep values were found to besmaller than the bulk value and to decrease when sodium ions were replaced by calcium ions.The agreement between ep values obtained from membrane potential measurements and thosecalculated from ion rejection rate data (ternary mixtures) highlights the global coherence ofthe transport model used and shows that membrane potential measured with electrolytemixtures can be used to determine the dielectric constant inside pores with no requirement ofadditional rejection rate measurements.

A antibioticoterapia em cirurgias de terceiros molares inferiores inclusos e/ou impactados é um assunto controverso no meio odontológico. O objetivo do presente estudo foi elucidar a real necessidade de prescrição de antibióticos nestes tipos de cirurgias realizadas por três operadores com experiências clínicas distintas. Um especialista, uma doutoranda e um aluno do último ano da graduação realizaram 50 cirurgias cada um, todas com remoção de osso e alto grau de dificuldade. Antibióticos não foram prescritos nos períodos pré e pós-operatório. No período préoperatório, 2o e 7o dias pós-operatórios foram analisados os seguintes parâmetros: dor, edema, trismo, temperatura corpórea, níveis de proteína C-reativa e contagem de neutrófilos salivares. Durante a cirurgia foram analisados: pressão arterial sistólica, diastólica e média, oximetria, freqüência cardíaca, qualidade da anestesia, quantidade de anestésico local, sangramento, dificuldade e tempo de duração da cirurgia. No dia da retirada de pontos, 7o dia pós-cirúrgico, foi avaliada a qualidade de cicatrização e os voluntários relataram a avaliação global do período póscirúrgico. Não houve nenhum caso comprovado de alveolite ou outro tipo de infecção no local operado. O tempo de cirurgia do graduando e da doutoranda mostraram valores médios maiores que os do especialista (p<0,05). Houve diferença estatisticamente significativa entre o graduando e os outros dois operadores nos seguintes parâmetros: qualidade da anestesia, quantidade de tubetes utilizados, sangramento no momento da incisão, trismo e dor em vários momentos pósoperatórios (p<0,05). Não houve mudanças significativas nos parâmetros hemodinâmicos durante as cirurgias. Os voluntários operados pela doutoranda tiveram uma recuperação da abertura de boca melhor que os operados pelos outros dois operadores (95,88±1,67% para a doutoranda, 86,87±2,05% para o especialista e 79,51±3,05% para o graduando, p<0,05). Houve diferença estatisticamente significativa nos níveis de proteína C-reativa no 2o dia de pós-operatório entre o graduando e o especialista e entre o graduando e a doutoranda (20,39±2,77 mg/L, 18,83±3,94 mg/L e 9,31±0,68 mg/L, respectivamente, p<0,05) e na contagem de neutrófilos salivares no 2o dia de pós-operatório entre os voluntários operados pelo graduando e os operados pela doutoranda (248±41,01 e 78,40±14,51 respectivamente, p<0,05). Os voluntários operados pela doutoranda avaliaram mais positivamente o período pós-cirúrgico em relação àqueles operados pelos outros dois operadores, possivelmente pela menor força e maior delicadeza exercida no momento da cirurgia. A análise conjunta dos resultados obtidos nesta pesquisa permite concluir que a antibioticoterapia mostra-se desnecessária em cirurgias de terceiros molares com necessidade de osteotomia independentemente da experiência do operador. / The use of antibiotics in lower third molar surgeries with necessity of boné removal is controversial. The aim of this study was to elucidate the real necessity of antibiotics prescription in such types of surgeries performed by three different surgeons with distinct clinical experiences. A specialist, a PhD student and a senior dental student performed 50 surgeries each, all with osteotomy and high degree of difficulty. Antibiotics were not prescribed either before or after surgeries. In the preoperatory period and on the second and seventh postoperative days, the following parameters were analyzed: pain, swelling, trismus, body temperature, C-reactive protein levels and salivary neutrophil count. During the surgeries the following parameters were analyzed: systolic, diastolic and mean arterial pressure, oxymetry, heart rate, quality of anesthesia, amount of local anesthetic, bleeding, surgery difficulty and duration of surgery. At the suture removal, seventh postoperative day, quality of wound healing and global evaluation performed by the patient were recorded. There was no confirmed case of dry socket or another type of local infection in the study. The duration of surgeries performed by the senior student and the PhD student showed higher values as compared to the specialist (p<.05). There was statistically significant difference between the senior student compared to both surgeons in the following parameters: quality of anesthesia, amount of local anesthetic, bleeding at incision time, trismus and pain at several postoperative times (p<.05). There were no significant changes in hemodynamic parameters during the surgeries. The PhD students volunteers had better recovery of mouth opening in comparison with the volunteers of the other surgeons (95.88±1.67% for the PhD student, 86.87±2.05% for the specialist, and 79.51±3.05% for the senior student, p<.05). There was significant statistically difference in C-reactive protein levels between the senior student and the specialist, and between the senior student and the PhD student (20.39±2.77 mg/L, 18.83±3.94 mg/L and 9.31±0.68 mg/L, respectively, p<.05), and in salivary neutrophil counts on the second postoperative day between the senior students patients and the PhD students patients (248±41.01 and 78.40±14.51 respectively, p<.05). The PhD students volunteers evaluated the postoperative period more positively in comparison to the volunteers of the other surgeons. Taken together, the results of the present work allow to conclude that antibiotics prescription is not necessary in lower third molar removal with osteotomy regardless of the surgeons experience.

Os materiais à base de céria (CeO2) e zircônia (ZrO2) estão presentes em diversas aplicações tecnológicas, destacando-se como anodo de células de combustível de óxido sólido (SOFC) e em catálise, tanto para a produção de hidrogênio, como na automotiva (Three-Way Catalysis). A solução sólida ZrxCe1-xO2- é de especial interesse, pois apresenta melhor estabilidade térmica e maior capacidade de armazenamento de oxigênio (OSC), quando comparada com os óxidos não dopados. Os materiais mesoporosos (poros de 2 a 50 nm) possuem elevada área superficial e permeabilidade a gases, características estas importantes para o desempenho das SOFCs e dos processos de catálise. Neste trabalho, zircônia-céria (Zr0,1Ce0,9O2-) mesoporosa foi sintetizada pelo processo sol-gel, utilizando, como precursores, os cloretos inorgânicos (ZrCl4 e CeCl3.7H2O), o copolímero em bloco P123 (PEO20PPO70PEO20) como direcionador de estrutura e o TIPB (tri-isopropil-benzeno) como agente dilatador. A solução passou por tratamento hidrotérmico durante 48h a 80°C, com posterior calcinação a 400°C para a remoção do polímero, resultando no óxido cristalizado. Na análise foram utilizadas as técnicas: difração de raios X em alto ângulo (XRD), espalhamento de raios X a baixo ângulo (SAXS), isotermas de adsorção de nitrogênio (NAI) e microscopia eletrônica de varredura e transmissão (SEM e TEM). Os resultados mostraram que o material possui elevada área superficial (110m2/g), mesoporos de várias dimensões, atingindo valores médios em torno de 30 nm, fase majoritariamente cúbica Fm3m e, em menor proporção, tetragonal P42/nmc. As micrografias revelaram que o óxido está totalmente nano-cristalizado, com os poros tipo fendas e uma mesoporosidade secundária com distribuição de tamanhos menor e mais estreita. Quatro amostras foram sintetizadas com diferentes razões em massa TIPB/P123 (0, 1, 2 e 4), de forma que foi possível verificar um aumento na dimensão dos poros devido à inclusão do dilatador. As demais propriedades estruturais e morfológicas mantiveram-se inalteradas entre todas as amostras, mesmo com diferentes quantidades de TIPB. / The ceria (CeO2) and zirconia (ZrO2) based materials are present in several technological applications, mainly as Solid Oxide Fuel Cells (SOFC) anodes and catalysts, for hydrogen production and automotive converter (Three-Way Catalysis). The solid solution ZrxCe1-xO2- has attracted special attention, since it shows better thermal stability and higher oxygen storage capacity (OSC), if compared to the non-doped oxides. The mesoporous materials (pores of 2 to 50 nm) show high surface area and gas permeability, important properties for SOFCs and catalysts efficiency. In this work, mesoporous ceria-zirconia (Zr0,1Ce0,9O2-) was synthesized by a sol-gel route using inorganic chlorides (ZrCl4 e CeCl3.7H2O) as precursors, block copolymer P123 (PEO20PPO70PEO20) as template and TIPB (tri-isopropyl-benzene) as swelling agent. The solution was submitted to hydrothermal treatment for 48h at 80°C and calcined at 400°C to remove the template, resulting in the crystallized oxide. The characterization was performed by X-ray diffraction at high angles (XRD), small angle X-ray scattering (SAXS), nitrogen adsorption isotherms (NAI) and transmission and scanning electron microscopy (TEM and SEM). The results showed that the material has high surface area (110m2/g), a wide pore size distribution with mean values around 30 nm, predominant cubic phase Fm3m and, in less quantity, tetragonal P42/nmc. The micrographs revealed that the oxide is totally nano-crystallized, having pores with slit shape and a secondary smaller mesoporosity with a narrow size distribution. Four samples were produced with different TIPB/P123 mass rate (0, 1, 2, 4), therefore was possible to verify the pore size expansion due to the swelling addition. The structural and morphological properties remained unchanged, even with different quantities of TIPB.

O desenvolvimento de novos materiais a partir de elementos biodegradáveis com durabilidade considerável, versatilidade apreciável e baixo custo tem grande interesse na aplicação da bio-eletrônica. O presente trabalho objetiva a caracterização das propriedades físicas e químicas das membranas de quitosana obtidas a partir da neutralização da solução policatiônica de quitosana. O trabalho foi dividido em duas etapas: solubilização e neutralização. Na primeira etapa a quitosana foi solubilizada em três concentrações diferentes de ácido acético (1%, 0.8% e 0.5%) para avaliar se a concentração de ácido exerce diferença significativa nas propriedades físico-químicas das membranas de quitosana. Na segunda etapa o policátion de quitosana foi neutralizado com duas bases fortes (NaOH e KOH) em três concentrações molares diferentes (0.5, 1 e 5 molar) pelo método de gotejamento lento da base até atingir o pH de 6.0 no policátion e obter membranas com pH perto da neutralidade. A caracterização das membranas obtidas a partir do policátion de quitosana neutralizado mostrou que as concentrações de ácido acético não mudam de forma significativa as propriedades físico-químicas das membranas. Em contraste, o processo de neutralização afetou as propriedades físico-químicas das membranas, e em particular, diferentes comportamentos foram observados dependendo da base utilizada. Membranas mais dúcteis foram obtidas após neutralização com KOH, exibindo capacidade plastificante pela base usada, enquanto que as membranas neutralizadas com NaOH apresentam um comportamento frágil. Além disso, as membranas neutralizadas com KOH exibem uma maior condução iônica em relação às propriedades elétricas das membranas, o qual pode ser interessante no desenvolvimento de biossensores ou célula combustível. / The development of new materials from biodegradable elements with considerable durability, versatility and low cost is of great interest for applications in bioelectronics. The present work aims the characterization of the chemical and physical properties of chitosan membranes after neutralization of the polycation solution of chitosan. This work was divided into two steps: solubilization and neutralization. In the first step, the chitosan was solubilized with three different concentrations of acetic acid (1%, 0.8% and 0.5%) in order to evaluate whether the acid affects the physical-chemical properties of the chitosan films. In the second step, the polycation of chitosan was neutralized with two different strong bases (NaOH and KOH) using three different molar concentrations (0.5, 1 and 5), by the slow drip method of base until reaching a pH of 6.0 for the polycation and obtaining films with pH close to neutrality. The characterization of the membranes obtained from neutralized chitosan showed that the different concentrations of acetic acid did not affect the physical-chemical properties of the films significantly. In contrast, the neutralization process did affect the physical-chemical properties, and particularly, different behaviors were observed depending on the type of base used for neutralization. More ductile films were obtained after neutralization with KOH, exhibiting plastificant capacity by the used base, whereas the films neutralized with NaOH exhibited a more fragile behavior. Beyond this, regarding the electrical properties, the films with KOH presented a higher ionic conductivity, which could be interesting for developing biosensors or fuel cells.