The purpose of this study was to evaluate the treatment efficiency of phenol contaminated soils by electrokinetic (EK) process conducted in sand boxes (60 cm¡Ñ30 cm¡Ñ30 cm; L¡ÑW¡ÑH). The electric field strength, electrode polarity reverse, and Fenton reagent were employed as the experimental factors in this study to assess the variations of soil characteristics, potential difference, and residual phenol concentration distribution during a treatment period of 20 days and after the treatment. It was found that the anode reservoir pH decreased to around 2 and the cathode reservoir pH increased to approximately 12 after 2~3 days of treatment in the no electrode polarity reverse system. However, the variation of pH in the anode and cathode reservoirs was less obvious in the case with electrode polarity reverse. No matter a constant potential system or a constant current system was employed, a general trend of a lower pH at the anode reservoir and a higher pH at the cathode reservoir would be found. The acid front generated at the anode reservoir flushed across the soil specimen toward the cathode and the base front advanced toward the anode. However, in the central region of sand box, unsaturated and saturated soil specimen maintain neutral. For EK or EK-Fenton experiments, under the constant potential conditions, the potential difference relative to the cathode versus the distance from anode was found to have a linear relationship at the beginning of the electrical potential application. As the treatment time elapsed, the potential gradient became non-linear. Nevertheless, there was no remarked potential gradient change in the case with electrode polarity reverse. Although capillarity has resulted in an increase of the moisture content of unsaturated soil (from 25.34% to 30% after 20 days), electroosmotic (EO) flow was not obvious in the unsaturated zone. For the experiments with electrode polarity reverse, they had a much greater EO flow quantity, the electroosmotic permeability coefficients for constant potential and constant current systems were 6.42¡Ñ10-6 cm2/V¡Es and 9.47¡Ñ10-6 cm2/V¡Es, respectively. It was also found that the existence of contaminants did reduce the EO flow quantity. Regardless of the employment of a constant potential or constant current system, the maximum destruction and removal efficiency (DRE) of phenol was obtained for EK-Fenton process. The maximum DRE values of phenol for both constant potential and constant current systems were found to be 78.06% and 80.11%, respectively. However, the DRE of phenol was found to be much lower for the system with electrode polarity reverse. It was postulated that the destruction efficiency of phenol was less obvious than the removal efficiency in the electrode polarity reverse system. In addition, a frequent reverse of electrode polarity also resulted in a frequent change of EO flow direction. Thus, a flow hysteresis of phenol in the soil compartment was found.

Spectral element based numerical solvers are developed to simulate electrokinetically driven flows for micro-fluidic applications. Based on these numerical solvers, basic phenomena and devices for electrokinetic applications in micro and nano flows are systematically studied. As a first application, flow and species transport control in a grooved micro-channel using local electrokinetic forces are studied. Locally applied electric fields, zeta potential patterned grooved surfaces, and geometry are manipulated to control mixed electroosmotic/pressure driven flow in the grooved micro-channel. The controlled flow pattern enables entrapment and release of prescribed amounts of scalar species in the grooves. As another application, hydrodynamic/ electrokinetic focusing in a micro-channel is studied. External electric field, flow rate of pressure driven flow, and geometry in the micro-channel are manipulated to obtain the focusing point, which led to determination of the electrophoretic mobility and (relative) concentration of dilute mixtures. This technique can be used to identify and detect species in dilute mixtures.

Microfluidic technology has been grown rapidly in the past decade. Microfluidics can find wide applications in multiple fields such as medicine, electronics, chemical and biology. Micro-pumping is an essential part of a microfluidic system. This thesis presents the optimization process of AC electro-thermal micropump with respect to the geometry of electrode array and channel height.The thesis first introduces the theories of AC electrokinetic including dielectrophoresis, AC electro-osmosis (ACEO) and AC electro-thermal (ACET). Also presented are the basic theory and governing equations of microfluidics, the continuity equation, the Navier-Stokes equation, and the conservation of energy equation. AC electro-thermal effect results from the interplays between electric field, temperature field and fluid mechanics. Since the governing equations are highly non-linear, numerical simulation is extensively used to understand the effects of factors such as the electrode dimensions and channel height. By interfacing finite element analysis software COMSOL Multiphysics with Matlab, to the simulation model is able to scan the geometry variables so as to find the optimal micropump design. The optimization has been performed with respect to flow rate and power efficiency of the micropump.

Theoretical models for the electrokinetics of weakly permeable porous colloidal particles are absent from the literature. The understanding of this topic will be advanced through a systematic analysis of the standard electrokinetic equations, resulting in a theory for the electrophoretic mobility of weakly permeable porous colloidal particles. / The standard electrokinetic equations are employed to model the flux of solvent and ions outside the porous particle. To be consistent with this approach, the flux of solvent and ions in the pores must also be governed by the standard electrokinetic equations. However, in practice, only transport phenomena on the particle scale are observed and it is sufficient for information regarding pore-scale behaviour to be retained purely in the form of averaged quantities. To complete the theoretical description, the standard electrokinetic equations outside the particle must be coupled to particle-scale transport equations inside the particle via boundary conditions at the porous/free-fluid interface. / It has been shown experimentally and theoretically for coupled Stokes and Darcy flows, that the correct interfacial boundary condition for the tangential external flow is given by the Beavers-Joseph-Saffman (BJS) condition. The effect of the BJS boundary condition on the hydrodynamic drag on an oscillating porous particle is investigated. It is found that the particle may be regarded as impermeable with a slip length independent of frequency, and the resulting drag is significantly reduced in comparison with an equivalent impermeable particle that does not exhibit a slip length. / The transport of a general electrolyte solution through a rigid porous body subjected to a static (d.c.) electric field is studied. The pore-scale description is given by the standard electrokinetic equations, including the effects of ion diffusion, electromigration and convection. Homogenization theory is used to derive transport equations that capture the particle-scale behaviour. It is proven that the transport coefficient tensors obey Onsager’s reciprocal relations and the diagonal coefficient tensors are positive definite. / New interfacial boundary conditions are derived using conservation arguments supplemented by Stern-layer theory. When combined with the particle-scale transport equations, these boundary conditions incorporate four principal effects into the standard electrokinetic model: solvent slip and Stern-layer ionic conduction at the interface, and macroscopic ionic conduction together with the electroosmotic flow of solvent through the particle. / The method of matched asymptotic expansions is then used to construct an approximate solution to the aforementioned system, in the thin double-layer limit. An expression for the electrophoretic mobility of a weakly permeable colloidal sphere is produced that consists of a generalization of Smoluchowski’s formula to encompass porous particles, and a next order correction. For the first time, the effects of solvent slip and Stern-layer ionic conduction within the porous/free-fluid interface, in conjunction with macroscopic ionic conduction and electroosmosis through the particle, are exhibited. It is shown that solvent slip at the porous interface is overwhelmingly the dominant effect on the mobility of weakly permeable porous colloidal particles.

Diss. (sammanfattning) Uppsala : Univ., 2002. / Härtill 5 uppsatser.

Electrokinetic phenomena in liquid foams is at a junction between two areas. On one side is the investigation of liquid foam drainage, and on the other side is electrokinetics of surface driven flow on solid-liquid interfaces. However, the electrokinetic phenomena in liquid foam films significantly lack understanding. Therefore, the novelty of the thesis is to address the mentioned gap in three stages. The outcome has potential applications in a novel separation approaches of biological molecules such as proteins and DNA. In the first stage, the electrokinetic flow of a sufficiently thick (180 μm) free liquid film was investigated using cationic and anionic surfactants by confocal micron-resolution particle image velocimetry (μ-PIV). The reverse of the surface charge resulted in a shift in charge of the electrical double layer at the free liquid film interface, which caused the direction of the electroosmotic velocity to reverse. In each surfactant type used, the fluid velocity profiles were measured at different depths of the free liquid film (different z-planes). It was found how the fluid velocity varied with depth. Numerical simulations of the electroosmotic flow in the same system were also performed using Finite Element Method to understand the flow dynamics. A reasonably good agreement was found between the numerical simulations and the experimental results validating the model. In the second stage, instead of flow visualisation particles, rhodamine B (RB) and fluorescein isocyanate (FICT) dye were added to the free liquid film. Under the initial conditions of pH 7.2, RB is a neutral dye, and FICT has a -2 charge. Under an imposed electric field pH variations were detected and an interesting flow profile was observed. The CFD model developed earlier (stage one) was modified to include the local pH variation. The behaviour of the simulated pH had a good agreement with the behaviour of the FICT. Further confirmation of local pH variation was undertaken using extra new experiments which also showed a good agreed with the simulation. In the third stage, a liquid foam electrokinetic separation chamber was designed to extend the study to include practical applications. The first challenge was to achieve a stable foam under external electric field. A polymer-surfactant mixture can solve the stability problem. However, the mixture of polymers required an alkaline pH (>9) condition for the polymer mixture to be soluble in the aqueous system. Lectin and tetramethylrhodamine goat anti-rabbit (IgG) protein mixture with different molecular mass to charge ratio (50 kDa and 150 kDa) were injected near the anode. The system was monitored in three location: (a) in a vicinity of the injection region, (b) between the two electrodes and (c) in a vicinity of the cathode. In the region (a), a decay of the luminescence intensity of the fluorescein of the two proteins was noted with varying rate. In region (b), an increase followed by a decrease in fluorescein intensity of the proteins was observed again at a varying rate. In region (c), an increase of the dye concentration was observed and again at a different rate. The observed difference was caused by difference of the electrophoretic velocity of the two proteins. The setup proved that proteins could be separated based on their electrophoretic mobility inside a liquid foam. The findings from the thesis show the ability to manipulate fluid flow within a free liquid film, and inside a liquid foam system by an external DC electric field, is not only interesting academically but has potential application in a novel separation approach of biological molecules and beyond. The result show, with the correct surfactant formulation, it possible to make a stable foam under an electric field which can be set up for separation of proteins using foam electrokinetics.

Le générateur de vapeur est un composant essentiel du réacteur à eau pressurisée. Après 15 à 20 ans de fonctionnement du GV, un phénomène de colmatage est observé, qui induit le bouchage du passage folié entre les tubes GV et la plaque entretoise. Ce phénomène peut avoir de graves conséquences pour le fonctionnement de la centrale nucléaire. L’objectif majeur de cette thèse est d’approfondir les connaissances des mécanismes responsables de la formation du colmatage en identifiant et hiérarchisant les processus prépondérants. L’installation COLENTEC est un outil expérimental conçu pour reproduire des dépôts dans des conditions représentatives d’un GV. La post-caractérisation microscopique a permis d’identifier la contribution du phénomène de précipitation et le rôle d’initiation de la passivation du matériau. Les formes spécifiques du colmatage, lipping à l’entrée et rides le long de la plaque entretoise, n’ont pas été observées dans les essais COLENTEC. Cela peut être provoqué par l’absence de particules dans la section d’essai ou une vitesse insuffisante du fluide. Le flashing et le phénomène électrocinétique ont été supposés contribuer à la formation du colmatage. Une collaboration avec l’Université de Manchester a été établie au cours de ce travail afin d’étudier expérimentalement le phénomène électrocinétique. Les travaux effectués ont permis de mieux comprendre ce phénomène et de suggérer son influence considérable dans la formation du colmatage. Des quantifications numériques de chaque phénomène ont été réalisées, prédisant un rôle prédominant du phénomène électrocinétique. / The steam generator is an essential component in PWR. After 15-20 years of functioning, an obstruction by deposits of flow holes between Tube Support Plate (TSP) and primary tubes is observed, called TSP clogging. This phenomenon may lead to dramatic consequences for nuclear power plant operation. The aim of this thesis is to deepen the understanding of the mechanisms responsible for TSP clogging by identifying and prioritizing the preponderant processes. COLENTEC is an experimental facility designed to reproduce TSP clogging deposits under representative conditions. Microscopic characterizations allowed revealing the deposit formation by precipitation and the initiation role of material passivation in deposit formation. Lipping and ripple forms, specifying TSP clogging, were not observed in COLENTEC tests. This is suggested to be caused by insufficient concentration of suitable particles at the test section. Particle deposition is supposed to be essential for the formation of lipping deposits. Electrokinetic and flashing phenomena are supposed to contribute to TSP clogging formation. An experimental collaboration with the University of Manchester was established to better understand the clogging formation by investigating the role of electrokinetic phenomenon. This study allowed reforming deposits with lipping and ripple forms as observed in EDF steam generators. Electrokinetic involvement, strongly affected by flow velocity, was considerably suggested in TSP clogging formation. Numerical quantification of deposit formation by each phenomenon was performed and compared to EDF feedbacks. Electrokinetic phenomenon was found to play a predominant role.

Os frutos de S. saponaria, espécie bastante abundante em São Carlos e outras regiões do Brasil são ricos em glicosídeos anfifílicos, ou seja, compostos por uma parte polar e outra apolar. Devido a esta peculiaridade tendem a formar espuma mostrando propriedades químicas semelhantes às dos tensoativos. Alguns destes glicosídeos pertencem à classe das saponinas e são constituídos por uma aglicona de estrutura carbônica a qual está ligada a uma ou duas cadeias de açúcar. O interesse pelas propriedades tensoativas deste glicosídeos motivou o estudo destas substâncias para uso em eletroforese capilar. Os frutos foram extraídos com metanol e fracionados em coluna cromatográfica preparativa utilizando sephadex LH-20 como fase estacionária. Após a eluição, as frações foram analisadas por espectrometria de massas e estudadas por eletroforese capilar. A eletroforese capilar de zona mostrou-se uma técnica viável para o estudo das frações obtidas. Embora um grau de pureza elevado não tenha sido alcançado, a fração B foi utilizada como aditivo para tampão em cromatografia eletrocinética micelar (MEKC) e uma interação diferenciada foi observada do nitrobenzeno com o tampão aditivado em relação ao tampão com SDS puro. / Sapindus saponaria is a very abundant species in São Carlos and others regions of Brazil. Fruits of S. saponaria have a high content of glycosides which possess well-defined regions of hydrophobic and hydrophilic feature denominated amphiphilic molecule. Thus, this can form a foam showing chemical proprieties equals to surfactants. Some glycosides belong to class of saponins and are composed of carbonic structure designates aglycone, which is linked in one or two sugar chains. The purpose of the present study was the use of glycosides due to their surfactants properties in further applications of capillary electrophoresis. The extraction of crude fruits was carried out with methanol and this extract was fractionated in Sephadex LH-20. The fractions were analyzed for mass spectrometry and studied in capillary electrophoresis (CE). This is a feasible technique for the study of fractions obtained. Although a high degree of purity was not reached, the fraction B were used as additive for the electrolyte background in MEKC. The nitrobenzene showed different interaction with micellar system in the electrolyte background with fraction B.

This work was aimed to the problem of change of the content of selected phenolic substances during treatment and storage of medical plants. Flavonoids represent small, but very important group of phenolic compounds. The biggest attention was paid to quercetin and rutine.Content of phenolic substances was determined by method of micellar electrokinetic capillary chromatography (MECC) in case of 6 medicinal plants usually used in traditional and modern medicine.

A ezetimiba e a sinvastatina são fármacos hipolipidêmicos. A ezetimiba pertence à nova classe das 2 - azetidinona, inibidores e bloqueadores do colesterol intestinal. A sinvastatina pertence à classe dos inibidores competitivos da hidroxi-3-metilglutarilcoenzima A redutase (HMG-CoA), que é a última etapa regulada na síntese do colesterol. O objetivo do trabalho foi desenvolver e validar métodos por cromatografia liquida de alta eficiência (HPLC) e eletroforese capilar (CE), rápidos, seletivos e confiáveis para determinação dos hipolipidêmicos em formulações farmacêuticas. A separação cromatográfica foi realizada usando coluna Nano separation technologies (NST) Cianopropril (CN) (150 mmx 4,6 mm, com partícula 3,5 µm), e eluição isocrático usando água purificada: acetonitrila (48:52, v/v); vazão 0,8 mL/min e volume de injeção de 20 µL. A temperatura da coluna foi de 35 ºC e a detecção foi realizada com detector na região do UV em 238 nm. O método por cromatografia eletrocinética micelar (MEKC) foi desenvolvido utilizando capilar de sílica fundida 30 cm (comprimento efetivo) x 50 µm d.i. e eletrólito constituído de tetraborato de sódio (TBS) 20 mmol L-1: dodecil sulfato de sódio (SDS) 30 mmol L-1, pH 9,0 ajustado com 10% ácido fosfórico: acetonitrila 12% v/v. O tempo de injeção foi de 3 segundos com pressão hidrodinâmica de 20 mbar, voltagem aplicada de 30 kV e detecção no UV em 238 nm. Os métodos analíticos foram validados de acordo com os requerimentos vigentes da ANVISA, ICH e Farmacopéia Americana. Portanto, os métodos propostos demonstraram ser lineares, precisos, exatos e adequados para quantificação simultânea da ezetimiba e sinvastatina em formas farmacêuticas sólidas. / Ezetimibe and simvastatin are hipolipidemic drugs. Ezetimibe belongs to a new class of 2 - azetidione, inhibitors and blockers of intestinal chrolesterol. Simvastatin belongs a class of competitive inhibitors of 3-hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase, which is the last regulated step in the cholesterol synthesis. The aim of this project was to develop and validate fast, selective and reliable chromatographic and electrophoretic methods, to determine hypolipidemic drugs in pharmaceutical formulations. The chromatographic separation was carried out on a Nano separation technologies (NST) Cyanpropyl (CN) (150 mm x 4,6 mm, 3,5 µm), isocratic elution using purified water: acetonitrila (48:52 v/v), the flow rate was 0,8 mL/min and the injection volume was 20 µL. The column temperature was kept at 35 ºC and detection wavelength was set at 238 mn. The micellar electrokinetic chromatographic method was developed using a fused silica capillary column 30 cm (effective length) x 50 µm i.d, the electrolyte was constituted of 20 mmol L-1 tetraborate buffer solution: 30 mmol L-1 sodium dodecyl sulphate (SDS), pH 9.0 adjusted with 10% phosphoric acid: 12 % v/v acetonitrile. The injection time was 3 s at 20 mbar, the applied voltage was 30 kV and detection was set at 238 nm. The both methods were developed and validated according to ANVISA, ICH and US Pharmacopeia guidelines. Therefore, the proposed methods proved to be linear, precise, accurate and suitable for simultaneous quantitation of ezetimibe and simvastatin in solid pharmaceutical formulations.