Propriedades físicas do solo em sistemas de rotação de culturas conforme o uso de corretivos da acidez

O objetivo deste trabalho foi avaliar o efeito de sistemas de rotação de culturas e de corretivos da acidez nas propriedades físicas do solo. O experimento foi realizado entre outubro de 2006 e julho de 2008, em Botucatu, SP, em blocos ao acaso, com parcelas subdivididas e oito repetições. As parcelas foram constituídas por quatro sistemas de rotação: soja/pousio/milho/pousio, soja/aveia-branca/milho/feijão, soja/milheto/milho/guandu e soja/braquiária/milho/braquiária. As subparcelas consistiram do tratamento testemunha, sem correção, e da aplicação de 3,8 Mg ha-1 de calcário dolomítico (PRNT = 90%) ou de 4,1 Mg ha-1 de silicato de cálcio e magnésio (PRNT = 80%), na superfície de um Latossolo Vermelho argiloso. Foram determinadas: estabilidade de agregados, densidade do solo, porosidade total, macro e microporosidade, resistência do solo à penetração e umidade do solo. A aplicação dos corretivos de acidez em superfície não reduz a agregação do solo e aumenta a macroporosidade até 0,20 m de profundidade, após aplicação de silicato, e até 0,10 m, após aplicação de calcário. A manutenção do solo em pousio, na entressafra, prejudica a estruturação do solo, reduz a estabilidade de agregados e aumenta a resistência à penetração nas camadas superficiais. A semeadura de braquiária, entre as safras de verão, aumenta a estabilidade de agregados até 0,10 m de profundidade.

Otimização do processo de recuperação do cromo de efluentes de curtumes por microemulsões no extrator Morris

The tanning industries are those which transform animal hide or skin into leather. Due to the complexity of the transformation process, greater quantities of chemicals are being used which results in the generation of effluents with residual solids. The chromium in the residual waters generated by tanning tend to be a serious problem to the environment, therefore the recovery of this metal could result in the reduction of manufacturing costs. This metal is usually found in a trivalent form which can be converted into a hexavalent compound under acidic conditions and in the presence of organic matter. The present study was carried out with the objective to recover chromium through an extraction/re-extraction process using micro emulsions. Micro emulsions are transparent and thermodynamically stable system composed of two immiscible liquids, one forming the continuous phase and the other dispersed into micro bubbles, established by an interfacial membrane formed by surface active and co-surface active molecules. The process of recovering the chromium was carried out in two stages. The first, an extraction process, where the chromium was extracted in the micro emulsion phase and the aqueous phase in excess was separated. In the second stage, a concentrated acid was added to the micro emulsion phase rich in chromium in order to obtain a Winsor II system, where the water that formed in the micro emulsion phase separates into a new micro emulsion phase with a higher concentration of chromium, due to the lowering of the hydrophiles as well as the ionisation of the system. During the experimental procedure, a study was initiated with a synthetic solution of chromium sulphate passing onto the effluent. A Morris extractor was used in the extraction process. Tests were carried out according to the plan and the results were analysed by statistical methods in order to optimise the main parameters that influence the process: the total rate of flow (Q), stirring speed (w) and solvent rate (r). The results, after optimization, demonstrated that the best percentuals in relation to the chromium extraction (99 %) were obtained in the following operational conditions: Q= 2,0 l/h, w= 425 rpm and r= 0,375. The re-extraction was carried out at room temperature (28 °C), 40 °C and 50°C using hydrochloric acid (8 and 10 M) and sulphuric acid (8 M) as re-extracting agents. The results obtained demonstrate that the process was efficient enough in relation to the chromium extraction, reaching to re-extraction percentage higher than 95 %.

Aplicação de microemulsão na recuperação de petróleo de reservatórios carbonáticos

The large investment in exploration activities offshore Brazil has generated new findings, generally in carbonate reservoirs, with different wettability conditions usually considered in the sandstone, strongly water-wet. In general, the carbonates reservoirs tend to be oil-wet, it difficult to mobilize of oil these reservoirs. These oils can be mobilized by different methods, or it may reverse the wettability of the surface of the reservoir and facilitate the flow of oil, improving production rates. Thus, the objective of this work was to study the influence of inversion on the wettability of the rock in the production and recovery of petroleum from carbonate reservoirs, using microemulsions. Three systems were chosen with different classes of surfactants: a cationic (C16TAB), an anionic (SDS) and nonionic (Unitol L90). Studies of the influence of salinity on the formation of the microemulsion as well as the characterization of fluids using density and viscosity measurements were also performed. To verify the potential of microemulsion systems in changing the wettability state of the chalk oil-wet to water-wet, contact angle measurements were performed using chalk of neutral-wet as surface material. Overall, with respect to the ionic character of the surfactants tested, the cationic surfactant (C16TAB) had a greater potential for reversal in wettability able to transform the rock wettability neutral to strongly water-wet, when compared with the anionic surfactant (SDS) and nonionic (Unitol L90), which showed similar behavior, improving the wettability of the rock to water. The microemulsions of all surfactants studied were effective in oil recovery, resulting in 76.92% for the system with C16TAB, 67.42% for the SDS and 66.30% for Unitol L90 of residual oil

Nano emulsões aplicadas a recuperação avançada de petróleo

A exploração de petróleo está a cada dia em circunstâncias mais adversas, no que diz respeito à profundidade dos poços como também, em relação à fluidez do óleo. Os reservatórios de descobertas recentes não possuem energia própria para produzir ou os métodos convencionais não são eficientes para fazer com que esses reservatórios tenham uma vida útil elevada, devido a alterações das propriedades físico-químicas, como por exemplo a viscosidade, que torna o deslocamento do óleo pelos poros do reservatório até a superfície cada vez mais complexo. O presente trabalho tem como objetivo estudar a preparação, caracterização e a utilização de nanoemulsões obtidas a partir de sistemas microemulsionados, com e sem a presença de polímero. Esses sistemas foram aplicados como método químico de recuperação de petróleo, com o intuito de obter maior eficiência de volume de óleo deslocado. O interesse por esse tipo de sistema existe devido a sua baixa tensão superficial, o pequeno tamanho de gotícula e, principalmente, pelo baixo percentual de matéria ativa presente em sua composição. Os ensaios realizados para caracterizar esses sistemas foram: aspecto físico, medidas de tamanho de gotícula, índice de polidispersão, tensão superficial, pH e condutividade. Ensaios de reologia e de adsorção dos sistemas foram realizados com o objetivo de avaliar sua influencia na recuperação de petróleo. Os ensaios de recuperação foram realizados em um equipamento que simula as condições de um reservatório de petróleo, utilizando plugs de rocha arenito Botucatu. Esses plugs foram saturados com salmoura (KCl 2%) e com petróleo proveniente da Bacia Potiguar do campo de Ubarana. Após essas etapas foi realizada a recuperação convencional utilizando a salmoura e, por último, foi injetada, a nanoemulsão, como método de recuperação avançada. Os sistemas obtidos variaram de 0% à 0,4% de polímero. Os ensaios de tamanhos de partícula obtiveram como resultado uma variação de 9,22 a 14,8 nm, caracterizando que as nanoemulsões estão dentro da faixa de tamanho inerente a esse tipo de sistema. Para ensaios de tensão superficial os valores foram na faixa de 33,6 a 39,7 dynas/cm, valores semelhantes à microemulsões e bem abaixo da tensão superficial da água. Os resultados obtidos para os valores de pH e condutividade se mantiveram estáveis ao longo do tempo de armazenamento, essa avaliação indica estabilidade das nanoemulsões estudadas. O teste de recuperação avançada utilizando nanoemulsão com baixo percentual de matéria ativa obteve como resultado de eficiência de deslocamento 39,4%. Porém esse valor foi crescente, de acordo com o aumento do percentual de polímero na nanomeulsão. Os resultados de eficiência de deslocamento de petróleo estão diretamente relacionados com o aumento da viscosidade das nanoemulsões. A nanoemulsão V (0,4% polímero) é o sistema mais viscoso dentre os analisados, e obteve o maior percentual de óleo deslocado (76,7%), resultando na maior eficiência de deslocamento total (90%). Esse estudo mostrou o potencial de sistemas nanoemulsionados, com e sem polímeros, na recuperação avançada de petróleo. Eles apresentam algumas vantagens com relação a outros métodos de recuperação avançada, como: o baixo percentual de matéria ativa, baixo índice de adsorção do polímero, dissolvido em nanoemulsão, na rocha e alta eficiência de recuperação

Equilíbrio líquido-líquido de sistemas aquosos com tensoativos polietoxilados: dados experimentais e modelagem

The nonionic surfactants when in aqueous solution, have the property of separating into two phases, one called diluted phase, with low concentration of surfactant, and the other one rich in surfactants called coacervate. The application of this kind of surfactant in extraction processes from aqueous solutions has been increasing over time, which implies the need for knowledge of the thermodynamic properties of these surfactants. In this study were determined the cloud point of polyethoxylated surfactants from nonilphenolpolietoxylated family (9,5 , 10 , 11, 12 and 13), the family from octilphenolpolietoxylated (10 e 11) and polyethoxylated lauryl alcohol (6 , 7, 8 and 9) varying the degree of ethoxylation. The method used to determine the cloud point was the observation of the turbidity of the solution heating to a ramp of 0.1 ° C / minute and for the pressure studies was used a cell high-pressure maximum ( 300 bar). Through the experimental data of the studied surfactants were used to the Flory - Huggins models, UNIQUAC and NRTL to describe the curves of cloud point, and it was studied the influence of NaCl concentration and pressure of the systems in the cloud point. This last parameter is important for the processes of oil recovery in which surfactant in solution are used in high pressures. While the effect of NaCl allows obtaining cloud points for temperatures closer to the room temperature, it is possible to use in processes without temperature control. The numerical method used to adjust the parameters was the Levenberg - Marquardt. For the model Flory- Huggins parameter settings were determined as enthalpy of the mixing, mixing entropy and the number of aggregations. For the UNIQUAC and NRTL models were adjusted interaction parameters aij using a quadratic dependence with temperature. The parameters obtained had good adjust to the experimental data RSMD < 0.3 %. The results showed that both, ethoxylation degree and pressure increase the cloudy points, whereas the NaCl decrease

Estudo da influência de tensoativos em sistemas microemulsionados na extração de gálio e alumínio

Gallium is an important material used in the electronic industry whose demand in the world market is increasing in view of its potential applications. A selective technique is required to allow for the production of the metal, separated from aluminium. Due to the fact that microemulsions constitute an attractive alternative to metal extraction procedures, microemulsified systems have been employed as gallium-selective extraction agents. Two surfactants have been synthesized: sodium 12-N,N-diethylamino-9,10-dihydroxyestearate (AMINE) and saponified coconut oil (SCO), both produced from raw materials readily available in Northeastern Brazil. Also, the commercial extraction agent KELEX-100, conventionally used with the same purpose, has been used in this work for comparison. The optimization of the extraction process with microemulsions was carried out by investigating the influence of some parameters, namely the type of cosurfactant, the cosurfactant/surfactant (C/S) ratio, the pH and concentration of metals in the aqueous phase. Pseudoternary diagrams, which are representative of the microemulsified systems under study, have been constructed in order to establish the boundaries of the regions where the several Winsor systems are formed. An experimental planning methodology (Scheffé Net) has been used to optimize the extraction. The extraction percentage values were as high as 100% for gallium and 99.99% for aluminium for the system with KELEX-100; 96.6% for gallium and 98.8% for aluminium for the system containing AMINE; and 88% for gallium and 85% for aluminium for the system with SCO. The microemulsified system chosen for presenting the best results in gallium extraction was composed by SCO/isoamyl alcohol/kerosene/Bayer licquor with a C/S ratio of 28 and pH of the original aqueous phase of 6.0. The selectivity that has not been observed in the extraction stage was accomplished in the reextraction process using HCl. For the KELEX-100 system, gallium was reextracted at 100% with 6M HCl and aluminium was reextracted at 100% with 0.8M HCl. For the AMINE system, the reextraction percentages were also 100% for both metals, using 6M HCl for gallium and 0.5M HCl for aluminium. On the other hand, the reextraction percentages for the system with SCO were as high as 84% for gallium and 92% for aluminium, with HCl in the same concentrations as those used in the AMINE system. Finally, an optimized system was applied in the gallium extraction process employing a reciprocating perforated-plates extractor. As a result, the metal content was extracted at a recovery rate of 95% for gallium and 97% for aluminium

Métodos de recuperação pós-exercício: uma revisão sistemática

A recuperação pós-exercício consiste em restaurar os sistemas do corpo a sua condição basal, proporcionando equilíbrio e prevenindo a instalação de lesões e, nesse sentido, torna-se aspecto importante de todo programa de condicionamento físico, em quaisquer níveis de desempenho, mas, sobretudo nos mais elevados. O objetivo desta revisão foi reunir informações e descrever as respostas proporcionadas por métodos recuperativos pós-exercício, como crioterapia, contraste, massagem e recuperação ativa, constituindo uma fonte de atualização do referido tema. Utilizaram-se os bancos de dados MedLine, Scielo e Lilacs, como lista de periódicos, o SportsDiscus. Foram incluídos no estudo somente ensaios clínicos randomizados controlados e não-controlados, além de artigos de revisão referentes ao tema proposto. Optou-se por procurar os termos: cryotherapy, massage, active recovery, thermotherapy, immersion e exercise, individualmente e em cruzamentos. Como achado, observou-se que alguns estudos relatam que a crioterapia é prejudicial em se tratando de recuperação pós-exercício, pois reduz o desempenho imediatamente após a aplicação da técnica. Por outro lado, estudos apontam como sendo benéfica, pois reduzem o nível de creatinaquinase após alta intensidade de esforço, evitando danos musculares. Para o contraste, embora apresente significância em se tratando de remoção de lactato sanguíneo, sua efetividade necessita ser mais bem discutida. Na massagem e na recuperação ativa, os principais vieses descritos dizem respeito à pressão exercida e à intensidade do exercício, respectivamente. Entre as técnicas, as que parecem ter efeitos semelhantes são o contraste e a recuperação ativa, no que tange à remoção de lactato e diminuição da creatinaquinase. Ressalta-se que o tempo de exposição é de fundamental importância para todos os métodos. Entretanto, diversos estudos não se propõem a identificar os reais efeitos fisiológicos promovidos pelas técnicas, utilizando-as de modo inipiente. Portanto, a inconsistência dos resultados encontrados sugere que a análise das variáveis utilizadas como método de recuperação deve ser mais bem controlada.

Fractais e Percolação na Recuperação de Petróleo

The complex behavior of a wide variety of phenomena that are of interest to physicists, chemists, and engineers has been quantitatively characterized by using the ideas of fractal and multifractal distributions, which correspond in a unique way to the geometrical shape and dynamical properties of the systems under study. In this thesis we present the Space of Fractals and the methods of Hausdorff-Besicovitch, box-counting and Scaling to calculate the fractal dimension of a set. In this Thesis we investigate also percolation phenomena in multifractal objects that are built in a simple way. The central object of our analysis is a multifractal object that we call Qmf . In these objects the multifractality comes directly from the geometric tiling. We identify some differences between percolation in the proposed multifractals and in a regular lattice. There are basically two sources of these differences. The first is related to the coordination number, c, which changes along the multifractal. The second comes from the way the weight of each cell in the multifractal affects the percolation cluster. We use many samples of finite size lattices and draw the histogram of percolating lattices against site occupation probability p. Depending on a parameter, ρ, characterizing the multifractal and the lattice size, L, the histogram can have two peaks. We observe that the probability of occupation at the percolation threshold, pc, for the multifractal is lower than that for the square lattice. We compute the fractal dimension of the percolating cluster and the critical exponent β. Despite the topological differences, we find that the percolation in a multifractal support is in the same universality class as standard percolation. The area and the number of neighbors of the blocks of Qmf show a non-trivial behavior. A general view of the object Qmf shows an anisotropy. The value of pc is a function of ρ which is related to its anisotropy. We investigate the relation between pc and the average number of neighbors of the blocks as well as the anisotropy of Qmf. In this Thesis we study likewise the distribution of shortest paths in percolation systems at the percolation threshold in two dimensions (2D). We study paths from one given point to multiple other points

Fractais e percolação na recuperação de Petróleo

The complex behavior of a wide variety of phenomena that are of interest to physicists, chemists, and engineers has been quantitatively characterized by using the ideas of fractal and multifractal distributions, which correspond in a unique way to the geometrical shape and dynamical properties of the systems under study. In this thesis we present the Space of Fractals and the methods of Hausdorff-Besicovitch, box-counting and Scaling to calculate the fractal dimension of a set. In this Thesis we investigate also percolation phenomena in multifractal objects that are built in a simple way. The central object of our analysis is a multifractal object that we call Qmf . In these objects the multifractality comes directly from the geometric tiling. We identify some differences between percolation in the proposed multifractals and in a regular lattice. There are basically two sources of these differences. The first is related to the coordination number, c, which changes along the multifractal. The second comes from the way the weight of each cell in the multifractal affects the percolation cluster. We use many samples of finite size lattices and draw the histogram of percolating lattices against site occupation probability p. Depending on a parameter, ρ, characterizing the multifractal and the lattice size, L, the histogram can have two peaks. We observe that the probability of occupation at the percolation threshold, pc, for the multifractal is lower than that for the square lattice. We compute the fractal dimension of the percolating cluster and the critical exponent β. Despite the topological differences, we find that the percolation in a multifractal support is in the same universality class as standard percolation. The area and the number of neighbors of the blocks of Qmf show a non-trivial behavior. A general view of the object Qmf shows an anisotropy. The value of pc is a function of ρ which is related to its anisotropy. We investigate the relation between pc and the average number of neighbors of the blocks as well as the anisotropy of Qmf. In this Thesis we study likewise the distribution of shortest paths in percolation systems at the percolation threshold in two dimensions (2D). We study paths from one given point to multiple other points. In oil recovery terminology, the given single point can be mapped to an injection well (injector) and the multiple other points to production wells (producers). In the previously standard case of one injection well and one production well separated by Euclidean distance r, the distribution of shortest paths l, P(l|r), shows a power-law behavior with exponent gl = 2.14 in 2D. Here we analyze the situation of one injector and an array A of producers. Symmetric arrays of producers lead to one peak in the distribution P(l|A), the probability that the shortest path between the injector and any of the producers is l, while the asymmetric configurations lead to several peaks in the distribution. We analyze configurations in which the injector is outside and inside the set of producers. The peak in P(l|A) for the symmetric arrays decays faster than for the standard case. For very long paths all the studied arrays exhibit a power-law behavior with exponent g ∼= gl.

Desenvolvimento e implantação de um sistema de gestão de pedidos de informação endereçados à Universidade Federal do Rio Grande do Norte a partir do serviço de informações ao cidadão (E-SIC)

Among the numerous policy changes that the world has experienced in recent years, occupies a prominent place in the quest for greater transparency of public agencies. Transparency has been an important tool in the accountability of the State to promote greater participation of the society by providing information that was previously restricted knowledge of public agencies. Brazil, following this trend, promulgated in May 2012 the Access to Information Act that seeks to disclose the actions of the State at all levels, in all public administration agencies. On the same day of the enactment of the law is provided society with a site that is empowering citizens to make their requests for information to government agencies. The Federal University of Rio Grande do Norte, which at that time had no a tool to assist them in managing this demand. This project has the objective to describe, build and implement a solution to solve this problem using Design Science Research as methodology. As result, the solution built in this research became a new module of the institution s ERP became it capable to control the entire process, and will be helpful to others partners which use our system ERP

Sistemas certificáveis de gestão ambiental e da qualidade: práticas para integração em empresas do setor moveleiro

O principal objetivo deste artigo é propor, a partir do referencial teórico e de um estudo de caso em uma empresa moveleira, práticas para integração de sistemas certificáveis de gestão ambiental e da qualidade. A coleta de dados do estudo de caso se deu por meio de entrevistas semiestruturadas com o responsável direto pelos dois sistemas e com alguns colaboradores-chave do nível operacional, além de análise documental e de visitas in loco. Ao final deste artigo, são propostas práticas para integração desses sistemas, relacionadas aos seguintes elementos: alta administração; apoio administrativo, financeiro e pessoal; serviço de consultoria; coordenação do programa de integração; interface entre os sistemas; capacitação técnico-gerencial; sistema de liderança, prospecção, avaliação e desenvolvimento de fornecedores; sistema de informação; indicadores; comunicação com o cliente, e integração contínua.

Influência da acrilamida e da poliacrilamida em sistema microemulsionado visando aplicação na recuperação avançada de petróleo

This work aims to study the influence of two additives, the monomer, acrylamide and its polymer, polyacrylamide, solubilized in microemulsion systems and applied on enhanced oil recovery. By the microemulsion system obtained, it was chosen points into the phase diagram, presenting these compositions: 25%, 30%, 35% C/T; 2% Fo (fixed for all points) e 73%, 68% e 63% Fa, respectively. However, the monomer and the polymer were solubilized in these microemulsion points with 0.1%; 0.5%; 1% e 2% of concentration, ordering to check the concentration influence at the physicochemical properties (surface tension and rheology) of the microemulsion. Through the salinity study, was possible to observe that the concentrations of 1% and 2% of polymer made the solution became blurred, accordingly, the study of surface tension and rheology only was made for the concentrations of 0.1% e 0.5% of monomer and polymer, respectively. By the surface tension study it was observed that how the concentration of active matter (C/T) was increasing the surface tension was amending for each system, with or without additives. In the rheology study, as it increases the concentration of active matter increases both the viscosity of the microemulsion system (SME) with no additive, as the SME with polymer (AD2). After the entire study, it was chosen the lower point of active matter (25% C/T; 2% Fo e 73% Fa), plus additives in concentrations of 0.1% and 0.5% to be used on enhanced oil recovery. Assays were made on sandstone from Botucatu Formation, where after the tests, it was concluded that among the studied points, the point who showed the best efficiency of advanced shift was the microemulsion system + 0.5% AD2, with a recovery of 28% of oil in place and a total of 96,49%, while the other solution with 0.5% of polymer presented the worst result, with 14.1% of oil in place and 67,39% of efficiency of total displacement

Estudo teórico aplicado ao petróleo: estabilidade dos alcenos e recuperação terciária

The present work aims to study the theoretical level of some processes employed in the refining of petroleum fractions and tertiary recovery of this fluid. In the third chapter, we investigate a method of hydrogenation of oil fractions by QTAIM (Quantum Theory of Atoms in Molecules) and thermodynamic parameters. The study of hydrogenation reactions, and the stability of the products formed, is directly related to product improvement in the petrochemical refining. In the fourth chapter, we study the theoretical level of intermolecular interactions that occur in the process of tertiary oil recovery, or competitive interactions involving molecules of non-ionic surfactants, oil and quartz rock where oil is accumulated. Calculations were developed using the semiempirical PM3 method (Parametric Model 3). We studied a set of ten non-ionic surfactants, natural and synthetic origin. The study of rock-surfactant interactions was performed on the surface of the quartz (001) completely hydroxylated. Results were obtained energetic and geometric orientations of various surfactants on quartz. QTAIM was obtained through the analysis of the electron density of interactions, and thus, providing details about the formation of hydrogen bonds and hydrogen-hydrogen systems studied. The results show that the adsorption of ethoxylated surfactants in the rock surface occurs through the hydrogen bonding of the type CH---O, and surfactants derivatives of polyols occurs by OH---O bonds. For structures adsorption studied, the large distance of the surfactant to the surface together with the low values of charge density, indicate that there is a very low interaction, characterizing physical adsorption in all surfactants studied. We demonstrated that surfactants with polar group comprising oxyethylene units, showed the lowest adsorption onto the surface of quartz, unlike the derivatives of polyols

Obtenção de sistemas microemulsionados e estudo de simulação por dinâmica molecular de sistemas micelares objetivando a veiculação de produtos naturais bioativos

Among the new drugs launched into the market since 1980, up to 30% of them belong to the class of natural products or they have semisynthetic origin. Between 40-70% of the new chemical entities (or lead compounds) possess poor water solubility, which may impair their commercial use. An alternative for administration of poorly water-soluble drugs is their vehiculation into drug delivery systems like micelles, microemulsions, nanoparticles, liposomes, and cyclodextrin systems. In this work, microemulsion-based drug delivery systems were obtained using pharmaceutically acceptable components: a mixture Tween 80 and Span 20 in ratio 3:1 as surfactant, isopropyl mirystate or oleic acid as oil, bidistilled water, and ethanol, in some formulations, as cosurfactants. Self-Microemulsifying Drug Delivery Systems (SMEDDS) were also obtained using propylene glycol or sorbitol as cosurfactant. All formulations were characterized for rheological behavior, droplet size and electrical conductivity. The bioactive natural product trans-dehydrocrotonin, as well some extracts and fractions from Croton cajucara Benth (Euphorbiaceae), Anacardium occidentale L. (Anacardiaceae) e Phyllanthus amarus Schum. & Thonn. (Euphorbiaceae) specimens, were satisfactorily solubilized into microemulsions formulations. Meanwhile, two other natural products from Croton cajucara, trans-crotonin and acetyl aleuritolic acid, showed poor solubility in these formulations. The evaluation of the antioxidant capacity, by DPPH method, of plant extracts loaded into microemulsions evidenced the antioxidant activity of Phyllanthus amarus and Anacardium occidentale extracts. For Phyllanthus amarus extract, the use of microemulsions duplicated its antioxidant efficiency. A hydroalcoholic extract from Croton cajucara incorporated into a SMEDDS formulation showed bacteriostatic activity against colonies of Bacillus cereus and Escherichia coli bacteria. Additionally, Molecular Dynamics simulations were performed using micellar systems, for drug delivery systems, containing sugar-based surfactants, N-dodecylamino-1-deoxylactitol and N-dodecyl-D-lactosylamine. The computational simulations indicated that micellization process for N-dodecylamino-1- deoxylactitol is more favorable than N-dodecyl-D-lactosylamine system.

Sistema microemulsionado: caracterização e aplicação na indústria de petróleo

Alkyl polyethoxylates are surfactants widely used in vastly different fields, from oil exploitation to pharmaceutical applications. One of the most interesting characteristics of these surfactants is their ability to form micellar systems with specific geometry, the so-called wormlike micelle. In this work, microemulsions with three distinct compositions (C/T = 40 %, 30 % and 25 %) was used with contain UNITOL / butanol / water / xylene, cosurfactant / surfactante (C/S) ratio equal to 0,5. The microemulsion was characterized by dynamic light scattering (DLS), capillary viscometry, torque rheometry and surface tensiometry experiments carried out with systems based on xylene, water, butanol (cosurfactant) and nonaethyleneglycolmonododecyl ether (surfactant), with fixed surfactant:cosurfactant:oil composition (with and without oil phase) and varying the overall concentration of the microemulsion. The results showed that a transition from wormlike micelles to nanodrops was characterized by maximum relative viscosity (depending on how relative viscosity was defined), which was connected to maximum effective diameter, determined by DLS. Surface tension suggested that adsorption at the air water interface had a Langmuir character and that the limiting value of the surfactant surface excess was independent of the presence of cosurfactant and xylene. The results of the solubilization of oil sludge and oil recovery with the microemulsion: C/S = 40%, 30% and 25% proved to be quite effective in solubilization of oil sludge, with the percentage of solubilization (%solubilization) as high as 92.37% and enhanced oil recovery rates up to 90.22% for the point with the highest concentration of active material (surfactant), that is, 40%.