Remoção de frações de óleo leve e pesado de rocha calcária através de sistemas microemulsionados

In this research the removal of light and heavy oil from disintegrated limestone was investigated with use of microemulsions. These chemical systems were composed by surfactant, cosurfactant, oil phase and aqueous phase. In the studied systems, three points in the water -rich microemulsion region of the phase diagrams were used in oil removal experiments. These microemulsion systems were characterized to evaluate the influence of particle size, surface tension, density and viscosity in micellar stability and to understand how the physical properties can influence the oil recovery process. The limestone rock sample was characterized by thermogravimetry, BET area, scanning electron microscopy and X-ray fluorescence. After preparation, the rock was placed in contact with light and heavy oil solutions to allow oil adsorption. The removal tests were performed to evaluate the influence of contact time (1 minute, 30 minutes, 60 minutes and 120 minutes), the concentration of active matter (20, 30 and 40 %), different cosurfactants and different oil phases. For the heavy oil, the best result was on SME 1, with 20 % of active matter, 1 minute of contact time, with efficiency of 93,33 %. For the light oil, also the SME 1, with 20 % of active matter, 120 minutes of contact time, with 62,38 % of efficiency. From the obtained results, it was possible to conclude that microemulsions can be considered as efficient chemical systems for oil removal from limestone formations

Eficiência de extração de cobre e níquel utilizando sistemas microemulsionados bifásicos e trifásicos

The environmental impact due to the improper disposal of metal-bearing industrial effluents imposes the need of wastewater treatment, since heavy metals are nonbiodegradable and hazardous substances that may cause undesirable effects to humans and the environment. The use of microemulsion systems for the extraction of metal ions from wastewaters is effective when it occurs in a Winsor II (WII) domain, where a microemulsion phase is in equilibrium with an aqueous phase in excess. However, the microemulsion phase formed in this system has a higher amount of active matter when compared to a WIII system (microemulsion in equilibrium with aqueous and oil phases both in excess). This was the reason to develop a comparative study to evaluate the efficiency of two-phases and three-phases microemulsion systems (WII and WIII) in the extraction of Cu+2 and Ni+2 from aqueous solutions. The systems were composed by: saponified coconut oil (SCO) as surfactant, n-Butanol as cosurfactant, kerosene as oil phase, and synthetic solutions of CuSO4.5H2O and NiSO4.6H2O, with 2 wt.% NaCl, as aqueous phase. Pseudoternary phase diagrams were obtained and the systems were characterized by using surface tension measurements, particle size determination and scanning electron microscopy (SEM). The concentrations of metal ions before and after extraction were determined by atomic absorption spectrometry. The extraction study of Cu+2 and Ni+2 in the WIII domain contributed to a better understanding of microemulsion extraction, elucidating the various behaviors presented in the literature for these systems. Furthermore, since WIII systems presented high extraction efficiencies, similar to the ones presented by Winsor II systems, they represented an economic and technological advantage in heavy metal extraction due to a small amount of surfactant and cosurfactant used in the process and also due to the formation of a reduced volume of aqueous phase, with high concentration of metal. Considering the reextraction process, it was observed that WIII system is more effective because it is performed in the oil phase, unlike reextraction in WII, which is performed in the aqueous phase. The presence of the metalsurfactant complex in the oil phase makes possible to regenerate only the surfactant present in the organic phase, and not all the surfactant in the process, as in WII system. This fact allows the reuse of the microemulsion phase in a new extraction process, reducing the costs with surfactant regeneration

The effect of sodium chloride on the formation of W/O microemulsions in soy bean oil/surfactant/water systems and the solubilization of small hydrophilic molecules

Partial pseudoternary phase diagrams were constructed for soy bean oil (SBO)/surfactant/NaCl aqueous solution systems, at 25 degrees C, using the anionic sodium bis(2-ethylhexyl) sulfosuccinate (ACT) and zwiterionic phosphatidylcholine (PC) or mixtures of these surfactants. The isotropic single phase of water-in-oil (W/O) microemulsions (MEs) is shown in the phase diagram and their viscosity reported. ME samples containing small amount of surfactant exhibit slightly higher viscosity than pure SBO, and were used in the solubilization of small water soluble molecules. NaCl enhances the area of the ME phase and MEs with different surfactant composition exhibit different induction time as obtained from tests of oxidative stability, and so are the MEs enriched with ascorbic acid, folic acid and FeSO4, with the latter exhibiting lower stability. The so prepared enriched soy bean oil has potential application in food industry since the surfactants are food grade. (C) 2007 Elsevier B.V. All rights reserved.

Spontaneous symmetry breaking of Bose-Fermi mixtures in double-well potentials

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Doxorubicin biocompatible O/W microemulsion stabilized by mixed surfactant containing soya phosphatidylcholine

Microemulsions (ME) containing soya phosphatidylcholine (SPC/polyoxyethylenglycerol trihydroxystearate 40 (EU)/sodium oleate (SO) as surfactant cholesterol (CHO) as oil phase and aqueous buffer were studied. Pseudo-ternary phase diagrams of the investigated systems were obtained at constant SPC/EU/SO weight ratio 3.5:3.5:3.0 by titration, in order to characterize the proportions between the components to form clear systems. The dynamic light scattering results showed that the size of the oil droplets decreases significantly with the ratio of surfactant/oil phase added to system. Depending on the composition ME system could exhibit a thixotropic behavior. The apparent viscosity increased 25- and 13-folds with cholesterol concentration for drug-free and drug-load ME, respectively. It was also verified that the octanol/aqueous buffer partition coefficient (K-O/B) of doxorubicin (DOX) was pH dependent increasing abruptly above pH 6.0. It was possible to incorporate 2.24 mg/ml of DOX into ME. The incorporation of DOX in the ME systems increased the droplets size for all surfactant concentrations used in the system. The results suggest that DOX interacts with the microstructure of the ME at the studied pH increasing significantly the drug solubility. It was possible to conclude that the investigated ME can be a very promising vehicle as drug-carrier for administration of doxorubicin. (c) 2006 Elsevier B.V. All rights reserved.

Oil-in-water lecithin-based microemulsions as a potential delivery system for amphotericin B

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Planejamento e produção de um criostato de baixo custo para caracterização elétrica de materiais

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Formation and characterization of soy bean oil/surfactant/water microemulsions

Pseudoternary phase diagrams, at 25 degrees C, were constructed for the systems soy bean oil (SBO)/surfactant/water, with single anionic sodium bis(2-ethylhexyl)sulfosuccinate (AOT), nonionic monoolein (MO) and mixtures of these surfactants, showing the isotropic phase of W/O microemulsions (MEs). The area of ME formation in the phase diagrams was shown to be dependent of the relative amount of surfactants, being larger for MO:AOT equals to 2:1. Rheological and dynamic light scattering (DLS) studies indicated that the viscosity of the isotropic ME phase exhibited two different behaviors depending on composition. The viscosity of dry MEs initially decreased with increasing amount of water following a dilution line in the phase diagram, i.e., a constant surfactant:SBO percentage ratio. As the water content increased the relative viscosity attained a minimum and then increased. This minimum could be related to the transition between two ME regions, L-2 and L'(2), having different characteristics. DLS measurements confirm the existence of ordinary W/O ME droplets in the L-2 region and suggest the existence of another structure in the L'(2) region. The size of the MEs droplets in L-2 phase ranges from 3.6 to 16.5 nm, depending on composition of SBO, surfactant and water. Small angle X-ray scattering (SAXS) also indicates the existence of structures with different characteristics, for the SAXS curves exhibit a typical micelle asymmetrical peak at low scattering vector q for MEs in L-2 but a symmetrical correlation peak at higher q vector in L'(2). (c) 2006 Elsevier B.V. All rights reserved.

Magnetic properties of Ni(NO3)2·2H2O

This work is concerned with the magnetic properties of Ni(NO3)2·2H2O from (Hin-T) and (Hap-T) phase diagrams. From these diagrams we have obtained the values of Hc(0), TN and Tt. A comparison between experimental and theoretical values of Tt is made, where a Tt relation for a spin 1 metamagnetic model is found. © 1988.

On non-ideal and non-linear portal frame dynamics analysis using Bogoliubov averaging method

We apply the Bogoliubov Averaging Method to the study of the vibrations of an elastic foundation, forced by a Non-ideal energy source. The considered model consists of a portal plane frame with quadratic nonlinearities, with internal resonance 1:2, supporting a direct current motor with limited power. The non-ideal excitation is in primary resonance in the order of one-half with the second mode frequency. The results of the averaging method, plotted in time evolution curve and phase diagrams are compared to those obtained by numerically integrating of the original differential equations. The presence of the saturation phenomenon is verified by analytical procedures.

The fractional-nonlinear robotic manipulator: Modeling and dynamic simulations

In this paper, we applied the Riemann-Liouville approach and the fractional Euler-Lagrange equations in order to obtain the fractional-order nonlinear dynamics equations of a two link robotic manipulator. The aformentioned equations have been simulated for several cases involving: integer and non-integer order analysis, with and without external forcing acting and some different initial conditions. The fractional nonlinear governing equations of motion are coupled and the time evolution of the angular positions and the phase diagrams have been plotted to visualize the effect of fractional order approach. The new contribution of this work arises from the fact that the dynamics equations of a two link robotic manipulator have been modeled with the fractional Euler-Lagrange dynamics approach. The results reveal that the fractional-nonlinear robotic manipulator can exhibit different and curious behavior from those obtained with the standard dynamical system and can be useful for a better understanding and control of such nonlinear systems. © 2012 American Institute of Physics.

Stability and collapse of fermions in a binary dipolar boson-fermion 164Dy-161Dy mixture

We suggest a time-dependent mean-field hydrodynamic model for a binary dipolar boson-fermion mixture to study the stability and collapse of fermions in the 164Dy-161Dy mixture. The condition of stability of the dipolar mixture is illustrated in terms of phase diagrams. A collapse is induced in a disk-shaped stable binary mixture by jumping the interspecies contact interaction from repulsive to attractive by the Feshbach resonance technique. The subsequent dynamics is studied by solving the time-dependent mean-field model including three-body loss due to molecule formation in boson-fermion and boson-boson channels. Collapse and fragmentation in the fermions after subsequent explosions are illustrated. The anisotropic dipolar interaction leads to anisotropic fermionic density distribution during collapse. This study is carried out in three-dimensional space using realistic values of dipolar and contact interactions. © 2013 American Physical Society.

Ciclo reprodutivo de machos de Dendropsophus minutus (Anura, Hylidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento e caracterização físico-química de sistemas líquido cristalinos contendo palmitato de retinol: quantificação química, avaliação da atividade antioxidante, estudos de liberação e bioadesão in vitro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Arteroids: a poética do jogo e o jogo poético em redes digitais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)