scholarly journals DETERMINAÇÃO DO EQUILÍBRIO HIDRÓFILO-LIPÓFILO (EHL) DE ÓLEOS DE ORIGEM VEGETAL

2002 ◽  
Vol 3 (1) ◽  
Author(s):  
S. M. W. ZANIN ◽  
M. D. MIGUEL ◽  
M. C. CHIMELLI ◽  
A. B. OLIVEIRA
Keyword(s):  
Vegetable Oil ◽  
Emulsion Stability ◽  
Continuous Phase ◽  
Dispersed Phase ◽  
Molecular Formula ◽  
Interface Interaction ◽  
Specific Substance ◽  
Para Determinar

A estabilidade das emulsões depende intrìnsecamente da interação interfásica estabelecida pelo agente emulsivo, composto anfifílico, entre as fases imiscíveis que as constituem. A escolha, proporção e a característica do tensoativo a ser utilizado na preparação da emulsão almejada, são previstas pormeio da verificação dos valores de equilíbrio hidrófilo-lipófilo (EHL) das substâncias envolvidas, o que permite predizer o tipo de comportamento esperado do composto frente a substâncias polares ou apolares. Os tensoativos devem apresentar valor de EHL equivalente ao da fase dispersa, para poder mantê-la estabilizada frente à fase dispersante. Para determinar o valor de EHL pode-se recorrer a dados em literatura ou equações baseadas na fórmula molecular do composto. Entretanto, quando o EHL de uma substância específica é desconhecido ou a literatura cita em ampla faixa de valor, torna-se útil ensaiar o preparo de emulsões com o óleo cujo EHL deve ser determinado, utilizando-se de tensoativos de EHL conhecidos. Com a notificação do EHL do óleo, pode-se lançar mão de emulgentes ideais com mesmo valor de EHL. HYDROPHILE-LIPOPHILE BALANCE (HLB) DETERMINATION OF VEGETABLE OIL FAMILY Abstract Emulsion stability depends of interface interaction established by emulsifiers, anfiphilic compounds that adsorb between immiscible phases that formemulsion.Choosing, quantifying and characterizing surfactant to be used at desired emulsion preparation are provided through verifying hydrophilelipophile balance (HLB) which allows to predict compound expected behavior opposite polar and nonpolar substances. Surfactants must present HLB value equal to dispersed phase to stabilize it opposite continuous phase. Estimating HLB value can work about literature data resort, calculation which gives HLB from compound molecular formula definition. However, when specific substance’s HLB is unknown, essaying oil whose HLB must be determined emulsion preparation taking known HLB emulsifiers is useful. Getting oil HLB permits using ideal emulsifiers with same HLB value.

scholarly journals Microencapsulation of Vegetable Oil: Alternative Approaches Using Membrane Technology and Spray Drying

2017 ◽  
Vol 45 (2) ◽  
pp. 29-33 ◽  
Author(s):  
Krisztina Albert ◽  
Gyula Vatai ◽  
András Koris
Keyword(s):  
Spray Drying ◽  
Vegetable Oil ◽  
Membrane Fouling ◽  
Average Particle Size ◽  
Continuous Phase ◽  
Membrane Technology ◽  
Wall Material ◽  
Dispersed Phase ◽  
Average Particle ◽  
High Concentrations

Abstract Microencapsulation technology is a method that is widely used in the food industry. By comparing the latest encapsulation techniques, a significant number of publications concern membrane technology. The term “membrane- based encapsulation” entails that the first step of the technique is the preparation of emulsion with the help of microporous membranes. Generally, in microencapsulation technologies, the wall material is dissolved in a continuous phase and oil is dispersed within it. In the present investigation, a new method of preparing microcapsules composed of vegetable oil and maltodextrin was developed. In the first step, the wall material (maltodextrin) was dissolved in oil and considered as a dispersed phase, subsequently, it was introduced into a continuous phase (water) through a microporous membrane. A comparative study was conducted between conventional microencapsulation techniques and one developed in our laboratory. The average particle size of microcapsules prepared by our method is smaller than the size allowed by other methods. After encapsulation preparation, fine-tuned microcapsules were produced by spray drying. However, the main disadvantage of our proposed technology is rapid membrane fouling, because of high concentrations of solute in the dispersed phase. This problem can be eliminated by judicious and systematic investigations.

Phase Inversion in Two-Phase Liquid Systems

1992 ◽  
Vol 57 (7) ◽  
pp. 1419-1423
Author(s):  
Jindřich Weiss
Keyword(s):  
Interfacial Tension ◽  
Phase Inversion ◽  
Continuous Phase ◽  
Considerable Effect ◽  
Weak Dependence ◽  
Dispersed Phase ◽  
Two Phase ◽  
Liquid Systems ◽  
Phase Liquid

New data on critical holdups of dispersed phase were measured at which the phase inversion took place. The systems studied differed in the ratio of phase viscosities and interfacial tension. A weak dependence was found of critical holdups on the impeller revolutions and on the material contactor; on the contrary, a considerable effect of viscosity was found out as far as the viscosity of continuous phase exceeded that of dispersed phase.

Capillary pressure, osmotic pressure and bubble contact areas in foams

Soft Matter ◽  
2021 ◽  
Author(s):  
Reinhard Höhler ◽  
Jordan Seknagi ◽  
Andrew Kraynik
Keyword(s):  
Osmotic Pressure ◽  
Capillary Pressure ◽  
Continuous Phase ◽  
Dispersed Phase ◽  
Average Pressure ◽  
Contact Areas ◽  
The Difference

The capillary pressure of foams and emulsions is the difference between the average pressure in the dispersed phase and the pressure in the continuous phase.

Effect of Geometry on Droplet Generation in a Microfluidic T-Junction

2013 ◽  
Author(s):  
Katerina Loizou ◽  
Wim Thielemans ◽  
Buddhika N. Hewakandamby
Keyword(s):  
Aspect Ratio ◽  
Cross Section ◽  
Droplet Formation ◽  
Continuous Phase ◽  
Main Channel ◽  
Superficial Velocity ◽  
Droplet Generation ◽  
Dispersed Phase ◽  
Aspect Ratios ◽  
The Cross

The main aim of this study is to examine how the droplet formation in microfluidic T-junctions is influenced by the cross-section and aspect ratio of the microchannels. Several studies focusing on droplet formation in microfluidic devices have investigated the effect of geometry on droplet generation in terms of the ratio between the width of the main channel and the width of the side arm of the T-junction. However, the contribution of the aspect ratio and thus that of the cross-section on the mechanism of break up has not been examined thoroughly with most of the existing work performed in the squeezing regime. Two different microchannel geometries of varying aspect ratios are employed in an attempt to quantify the effect of the ratio between the width of the main channel and the height of the channel on droplet formation. As both height and width of microchannels affect the area on which shear stress acts deforming the dispersed phase fluid thread up to the limit of detaching a droplet, it is postulated that geometry and specifically cross-section of the main channel contribute on the droplet break-up mechanisms and should not be neglected. The above hypothesis is examined in detail, comparing the volume of generated microdroplets at constant flowrate ratios and superficial velocities of continuous phase in two microchannel systems of two different aspect ratios operating at dripping regime. High-speed imaging has been utilised to visualise and measure droplets formed at different flowrates corresponding to constant superficial velocities. Comparing volumes of generated droplets in the two geometries of area ratio near 1.5, a significant increase in volume is reported for the larger aspect ratio utilised, at all superficial velocities tested. As both superficial velocity of continuous phase and flowrate ratio are fixed, superficial velocity of dispersed phase varies. However this variation is not considered to be large enough to justify the significant increase in the droplet volume. Therefore it can be concluded that droplet generation is influenced by the aspect ratio and thus the cross-section of the main channel and its effect should not be depreciated. The paper will present supporting evidence in detail and a comparison of the findings with the existing theories which are mainly focused on the squeezing regime.

scholarly journals Liquid–Liquid Flows with Non-Newtonian Dispersed Phase in a T-Junction Microchannel

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 335
Author(s):  
Anna Yagodnitsyna ◽  
Alexander Kovalev ◽  
Artur Bilsky
Keyword(s):  
Flow Pattern ◽  
Dynamic Viscosity ◽  
Slug Flow ◽  
Shear Thinning ◽  
Continuous Phase ◽  
Immiscible Liquid ◽  
Dispersed Phase ◽  
Effective Dynamic ◽  
Liquid Flows ◽  
Shear Thinning Fluid

Immiscible liquid–liquid flows in microchannels are used extensively in various chemical and biological lab-on-a-chip systems when it is very important to predict the expected flow pattern for a variety of fluids and channel geometries. Commonly, biological and other complex liquids express non-Newtonian properties in a dispersed phase. Features and behavior of such systems are not clear to date. In this paper, immiscible liquid–liquid flow in a T-shaped microchannel was studied by means of high-speed visualization, with an aim to reveal the shear-thinning effect on the flow patterns and slug-flow features. Three shear-thinning and three Newtonian fluids were used as dispersed phases, while Newtonian castor oil was a continuous phase. For the first time, the influence of the non-Newtonian dispersed phase on the transition from segmented to continuous flow is shown and quantitatively described. Flow-pattern maps were constructed using nondimensional complex We0.4·Oh0.6 depicting similarity in the continuous-to-segmented flow transition line. Using available experimental data, the proposed nondimensional complex is shown to be effectively applied for flow-pattern map construction when the continuous phase exhibits non-Newtonian properties as well. The models to evaluate an effective dynamic viscosity of a shear-thinning fluid are discussed. The most appropriate model of average-shear-rate estimation based on bulk velocity was chosen and applied to evaluate an effective dynamic viscosity of a shear-thinning fluid. For a slug flow, it was found that in the case of shear-thinning dispersed phase at low flow rates of both phases, a jetting regime of slug formation was established, leading to a dramatic increase in slug length.

Formation of Two-Phase Multiple Emulsions by Inclusion of Continuous Phase into Dispersed Phase

Langmuir ◽  
2002 ◽  
Vol 18 (20) ◽  
pp. 7334-7340 ◽  
Author(s):  
Jong-Moon Lee ◽  
Kyung-Hee Lim ◽  
Duane H. Smith
Keyword(s):  
Continuous Phase ◽  
Dispersed Phase ◽  
Two Phase ◽  
Multiple Emulsions
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