Article

Influence of the Stirrer Initial Position on Emulsion Morphology. Making Use of the Local Water-to-Oil Ratio Concept for Formulation Engineering Purpose

Article

Influence of the Stirrer Initial Position on Emulsion Morphology. Making Use of the Local Water-to-Oil Ratio Concept for Formulation Engineering Purpose

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Abstract

The initial location of the stirrer in the emulsification vessel can induce the resulting emulsion type. The interpretation in terms of mixing phenomena leads to the use of the local water-to-oil ratio (WOR) concept in the formulation-composition map. The know-how associated with this phenomenology allows us to interpret in a straightforward way the kind of complex procedures commonly employed in emulsion manufacturing, particularly those associated with inversion and multiple emulsion attainment.

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... 6 Other factors have also proven to be important, such as the surfactant concentration, 7 the stirring intensity, 8 and the general emulsification protocol. 9 The emulsion type has been found to be closely related to the phase behavior of the surfactant/oil/water (SOW) system, 10−16 which depends on two types of variables: the formulation (intensive variables) and the composition (extensive variables; relative quantities of the main components S, O, and W). 17 Among the intensive variables, temperature is most often used to tune the affinity of polyethoxylated surfactants with respect to water and oil. All intensive variables (T, surfactant structure, nature of the oil phase, salinity, pH, etc.) have been gathered in a generalized formulation variable called the hydrophilic−lipophilic deviation (HLD) 18 based on the so-called "optimum formulation" concept. ...
... Once the phases had separated, an Ultra-Turrax IKA-T10 basic turbine was placed with the tip at the W/O interface to avoid favoring an emulsion type, as discussed elsewhere. 9 Then, a CDC749 conductivity microcell model connected to a Radiometer Analytical CDM 210 conductivity meter was placed in the vial. Finally, stirring was carried out at 8000 rpm for 20 s, after which the conductivity was read and the temperature was verified. ...
... Conductivity measurements of a series of systems with various surfactant concentrations and water/oil ratios allowed for the determination of the standard inversion line in the γ and χ maps. 9 2.3. Dynamic Phase Inversion. ...
Article
The relationship between the phase behavior and the type of emulsion formed under stirring has been studied for a well-defined surfactant/oil/water (SOW) system (ultrapure C10E4/n-octane/water) at three surfactant concentrations (1%, 3%, and 7%). The phase behavior was determined from systems equilibrated at constant temperature. The type of emulsions formed when these pre-equilibrated systems were stirred was established from conductivity measurements, and the so-called “standard inversion frontier” between the two emulsion morphologies (O/W and W/O) was plotted on temperature–water/oil proportion and temperature–surfactant concentration maps (χ and γ cuts, respectively, of the SOW–T prism). Dynamic phase inversions, produced by imposing a temperature variation under continuous stirring, were also observed. In the χ and γ maps, an exact correspondence between phase behavior and emulsion type was not observed, under either standard or dynamic conditions, and some regions of the formulation–composition map clearly shed light on a violation of Bancroft’s rule. The strong impact of kinetics (mass transfer of the components), especially at low surfactant concentration, was demonstrated in experiments performed under dynamic inversion conditions. The transitional branch position was found to be significantly affected by the dynamic process, and its extension between the two catastrophic branches was directly associated with the range of three-phase behavior, which, in turn, was quite dependent on surfactant concentration.
... Dentro de las variables de composición están la proporción de aceite y agua y la concentración del surfactante. Las variables de mezclado incluyen la intensidad y tiempo de agitación, el tipo y geometría del impulsor empleado, además del protocolo de mezcla (Salager et al. 2001). ...
... La figura 1 representa el sistema de agitación. Por ensayos previos se determinó la ubicación del rotorestator justo debajo de la interfase, en la fase acuosa, tal y como se recomienda en la literatura para garantizar la formación de emulsiones de aceite en agua (O/W) (Oldshue, 1990, Salager et al, 2001. ...
Article
Full-text available
In the Food Industry, highly-concentrated disperse phase emulsions (> 75%) are frequently produced, considering physicochemical and compositional parameters, and the mixing conditions. Most of the research related to the mixing of disperse systems has studied diluted systems without surfactants. The present work deals with the preparation of highly-concentrated corn oil in water emulsions with ethoxylated non ionic surfactant. The experimental method was based on factorial design 23 with central and axial points, where impeller rotational speed, time agitation and, oil: water ratio were varied. The influence of those variables on volume and surface area mean drop diameter of emulsions, d43and d32, respectively, was evaluated. Through the analysis of variance of experimental space, eliminating the non-significant effects, it was determined that d43can be predicted almost by 99% by a quadratic model, but this model, by itself, can not explain the d32whole extension response surface, because the lack of fit is considerable; however the quadratic model can be used to analyze the influence of the variables. A cubic fit was developed for the d32, this model presented confused terms that do not permit the determination of a final relationship between pure and crossed variables, but allows the exploration of the complete d surface response, because it represents better the experimental variability without lack of fit. The model’s assumptions normality, independence, and homocedasticity were satisfied.
... Los diámetros del impulsor y del recipiente fueron seleccionados de acuerdo con la relación geométrica óptima reportada por investigaciones previas, la cual se tiene como 1/3. La posición del impulsor con respecto al fondo del tanque fue fijada tomando en cuenta que varios trabajos anteriores indican que para la formación de una emulsión O/W, es apropiado colocar el impulsor en la fase acuosa, que se desea sea la continua, a modo de dispersar la fase oleica en ella (Oldshue, 1983;Salager et al. 2001). ...
... Inmediatamente a continuación (después de unos 30~45 segundos de agitación), se alcanzó el punto en el que se interrumpió el proceso y la emulsión se invirtió. Ya otros investigadores han descrito un proceso similar a éste, en el que la relación aceite-agua determina el tipo de emulsión formada, y ésta se mide de manera local en la zona de agitación (Salager et al. 2001). La emulsión resultante de este proceso no es completamente O/W ni W/O, dado que el proceso de inversión se detiene cuando cesa la agitación, según el protocolo utilizado. ...
... Previous works have reported the displacement of the standard inversion frontier with oil viscosity increase but only in the A þ /C þ region, for experiments carried out up to 0.5 Pa.s. 36,40 The present results show that in the A þ /C þ region the trend is curtailed as viscosity increases further; however, in the B À /A À region, the shift is limited by a composition restriction (100% oil concentration). The stirring speed may have an influence in the position of inversion frontier; 39 however, in the case of a viscous oil phase, a slow agitation (i.e. ...
... But, if the addition is "too fast" or the mixing "too sluggish", it is possible to create from place to place stagnant unmixed zones that promote a localized inversion phenomenon, in the direction demanded by the system formulation (as a different local water to oil ratio, WOR, is generated). 40 In the present study, the formation of multiple emulsions and the creation of stagnant unmixed zones depend on the oil viscosity. Thus, as the studied range of internal addition rate may be considered as a "slow addition" (for which formulation dominates and multiple emulsion morphology formation is supported) the results may be explained by the shear transfer effectiveness and the probability of collision between dispersed drops. ...
Article
This study deals with the description of the influence of oil viscosity and process conditions on catastrophic phase inversion, through the analysis of the effects of formulation and process variables on the dispersed phase fraction at which the inversion is triggered. The in situ simultaneous follow-up of viscosity and conductivity measurements allowed, from a process point of view, to emphasize the effect of the aqueous phase addition rate on the catastrophic phase inversion point (PIP) and multiple w/O/W emulsion formation. Thus if the aqueous phase is added by very small fractions, formulation dominates and the inversion phenomenon can be accelerated, as a consequence of multiple emulsion formation, that greatly increases the volume of effective dispersed phase. An increase in oil viscosity greatly increased the tendency of the oily phase to become the dispersed phase and promoted the formation of highly concentrated emulsions (about 80 to 95% in volume) after inversion.
... Although this rule deals with physicochemical affinity, it is far from offering adequate knowledge because of emulsion complexities. To describe emulsion production process, the volumetric water to oil ratio [9][10][11] and the emulsification protocol [12,13] also should be taken into account. Because of that, the research using well formalized experiments is of major importance to prevent that the competing factors blind the information of interest. ...
... When the electrolyte concentration increases, the lipophilicity of the system is generally favored. As shown in Fig. 1, phase equilibrium recordings were in accordance with results found in literature [4,12]. Increasing the water content makes the three phase behavior transition occurrence to be at lower salinities. ...
Article
This study investigated the inversion process in emulsions by the steady state emulsification protocol. Two model systems were tested. The first system contained sodium dodecyl sulfate (SDS) + n-pentanol/toluene. +heptane/water+sodium chloride. Phase equilibrium data guided emulsion inversion processes. Salinity and cosurfactant composition were the manipulated variables to emulsions reach the expected phase transitions. Results evidenced different phase behaviors when comparing systems of same formulation in thermodynamic equilibrium and emulsified (expanded area). Systems with WOR different than 1 and low surfactant content systems show prominent difference in phase behavior. A frontier between liquid dispersion and emulsion was scrutinized by increasing the surfactant content. The other investigated system here was composed of poly-ethoxylated nonylphenol/heptane + toluene/water +sodium chloride. It was inverted using a dynamic phase inversion temperature (PIT) procedure. This dynamic emulsion inversion was a reference to achieve the steady state inversion protocol, which consisted of adding solutions for change the mean hydrophilic characteristic of surfactant mixture.
... Dentro de las variables de composición están la proporción de aceite y agua y la concentración del surfactante. Las variables de mezclado incluyen la intensidad y tiempo de agitación, el tipo y geometría del impulsor empleado, además del protocolo de mezcla (Salager et al. 2001). ...
... La figura 1 representa el sistema de agitación. Por ensayos previos se determinó la ubicación del rotorestator justo debajo de la interfase, en la fase acuosa, tal y como se recomienda en la literatura para garantizar la formación de emulsiones de aceite en agua (O/W) (Oldshue, 1990, Salager et al, 2001. ...
Article
Full-text available
In the Food Industry, highly-concentrated disperse phase emulsions (> 75%) are frequently produced, considering physico-chemical and compositional parameters, and the mixing conditions. Most of the research related to the mixing of disperse systems has studied diluted systems without surfactants. The present work deals with the preparation of highly-concentrated corn oil in water emulsions with ethoxylated non ionic surfactant. The experimental method was based on factorial design 23 with central and axial points, where impeller rotational speed, time agitation and, oil: water ratio were varied. The influence of those variables on volume and surface area mean drop diameter of emulsions, d43 and d32, respectively, was evaluated. Through the analysis of variance of experimental space, eliminating the non-significant effects, it was determined that d43 can be predicted almost by 99% by a quadratic model, but this model, by itself, can not explain the d32 whole extension response surface, because the lack of fit is considerable; however the quadratic model can be used to analyze the influence of the variables. A cubic fit was developed for the d32, this model presented confused terms that do not permit the determination of a final relationship between pure and crossed variables, but allows the exploration of the complete d32 surface response, because it represents better the experimental variability without lack of fit. The model's assumptions of normality, independence, and homocedasticity were satisfied.
... Los diámetros del impulsor y del recipiente fueron seleccionados de acuerdo con la relación geométrica óptima reportada por investigaciones previas, la cual se tiene como 1/3. La posición del impulsor con respecto al fondo del tanque fue fijada tomando en cuenta que varios trabajos anteriores indican que para la formación de una emulsión O/W, es apropiado colocar el impulsor en la fase acuosa, que se desea sea la continua, a modo de dispersar la fase oleica en ella (Oldshue, 1983;Salager et al. 2001). ...
... Inmediatamente a continuación (después de unos 30~45 segundos de agitación), se alcanzó el punto en el que se interrumpió el proceso y la emulsión se invirtió. Ya otros investigadores han descrito un proceso similar a éste, en el que la relación aceite-agua determina el tipo de emulsión formada, y ésta se mide de manera local en la zona de agitación (Salager et al. 2001). La emulsión resultante de este proceso no es completamente O/W ni W/O, dado que el proceso de inversión se detiene cuando cesa la agitación, según el protocolo utilizado. ...
Article
Full-text available
The analysis of physico-chemical aspects (formulation-composition) associated with the characterization of a water in oil emulsion (O/W), manufactured by the Food Industry, is of a great importance due to its contribution into the knowhow of its elaboration process. This type of system must have good stability to endure long storage times, often under thermal stress. Edible corn oil in water emulsions, stabilized with a non ionic surfactant (HLB=15), were elaborated by direct emulsification, varying the water oil ratio (φ) and surfactant concentration. It was used a mixing system setting the geometrical dimensions of stator, impeller and the nominal potency of the engine. The studied properties were: conductivity, stability as percent of clarified and coalesced volume, viscosity, rheological behaviour and, drop size distribution. The information gathered was plotted as 3D plots. Conductivity was notably dependent on Internal Phase Ratio (IPR) and surfactant concentration. The higher stability was found to be that of 80% oil in water emulsions. Stability was higher at 50 °C than at 40 °C. The most concentrated emulsions showed a pseudoplastic behaviour, having a transition at 60% range, that lead to newtonian behaviour at lower concentrations (φ<50%).
... Cuve tournante, Vitesse imposée Des travaux précédents concernant l'influence de la viscosité de la phase huileuse sur la localisation de la ligne d'inversion standard avaient aussi mis en évidence le déplacement de la frontière d'inversion standard avec l'augmentation de la viscosité de l'huile (jusqu'à 0,5 Pa.s) mais seulement dans la région C + /A + (branche supérieure droite dans la carte), tandis que la frontière dans la région B -/A -(branche inférieure) demeurait inchangée 83,84 . Pour notre part, nous avons constaté un déplacement de la frontière dans la zone B -/Avers des fractions de phase dispersée plus faibles lorsque la viscosité de l'huile augmentait, mais ce déplacement est attenué avec l'augmentation de la viscosité. ...
... La formation des émulsions multiples seraient liées au changement de régime d'écoulement induit par le changement de la viscosité des systèmes. De leur coté Salager et Coll.24,83,84 , s'ils ont pu mettre en évidence un effet de la viscosité de la phase huileuse sur la ligne d'inversion standard dans la zone A + /C + , ils n'ont pas observé d'effet dans la zone B -/A -, ceci peut être explique par la viscosité relativement peu élevée (<0,5 Pa.s) des systèmes étudies(Figure 1.18).En régime laminaire, l'augmentation du rapport de viscosités (R v = η d /η c ) favorise la formation de gouttes ellipsoïdales 85 et la présence de gradients de vitesse dans la cuve86 . Les gouttes ellipsoïdales sont à l'origine de la formation de gouttes multiples qui peuvent s'interconnecter pour former des régions d'inversion localisées. ...
Thesis
Ce travail porte sur la description et la compréhension de l'inversion de phase catastrophique utilisée pour l'émulsification de produits visqueux, à travers l'analyse des effets de formulation et de procédé sur la fraction de phase dispersée à laquelle le processus se produit et sur les mécanismes mis en jeu. Les suivis rhéologique et conductimétrique simultanés in situ de l'émulsification ont permis, du point de vue procédé, de mettre en avant l'influence du débit d'addition de la phase aqueuse sur la formation d'émulsions multiples du type e/H/E lesquelles, en augmentant notablement la fraction de phase dispersée apparente, sont responsables de l'inversion dès de faibles fractions de phase dispersée ajoutée. Au niveau formulation, l'augmentation de la viscosité de l'huile induit de manière remarquable la tendance de cette phase à devenir le milieu dispersé, conduisant à une inversion pour de très faibles fractions de phase aqueuse et donc à des émulsions finales très concentrées (de 80 à 95% en volume). Le suivi au microscope du phénomène d'inversion de phase par l'intermédiaire d'un écoulement de type « squeezing flow », a permis d'établir les conditions et les mécanismes conduisant à une inversion complète ou seulement partielle. La viscosité relative des phases aqueuse et huileuse est responsable d'une inversion catastrophique suivant un mécanisme de type agglomération coalescence plutôt que de type inclusion/fuite tel que généralement admis. L'établissement d'un modèle mathématique basé sur les bilans de population et le caractère fractal du phénomène a permis de décrire l'évolution de la taille des gouttes multiples ainsi que la fraction de phase dispersée ajoutée à laquelle l'inversion se produit
... The shift of the inversion frontier can also be attained in some other way, eg by changing the original position of the stirrer with respect to the oil-water initial interface. 56,57 ...
... The contact time for a system to behave as if it were equilibrated, the so-called apparent pre-equilibration time, 57 can vary, largely depending on the formulation as well as on the stirring duration which can produce inversion by accumulated irreversibility. 66 Again, in these cases, the 3D diagram, though insufficient to explain the whole picture, might be useful to partially describe the process. ...
Article
All variables capable of altering the physico-chemical formulation, including temperature, are included in a generalized concept known as the hydrophilic–lipophilic deviation (HLD), which measures the departure from the reference state at which the surfactant–oil–water system exhibits Winsor III three-phase behaviour. The general phenomenology representing the emulsion properties (type, stability, viscosity, drop size) can be qualitatively charted in a three-dimensional map, where each region exhibits definite features. Travelling across the map from one region to another corresponds to modifications in formulation, composition and stirring along a path which can describe the protocol of change in an industrial process dealing with emulsion making, inversion or reworking. Six different path cases, labelled as unit operations, emerge from a systematic categorizing, and allow the interpretation of complex industrial processes such as crude oil dehydration, or the manufacturing of paint, cosmetics or heavy hydrocarbon emulsions.© 2003 Society of Chemical Industry
... The phase that does not contain the impeller is gradually dragged into the continuous phase and becomes the dispersed phase. Such a mixing procedure results in a gradual variation of HLB of the emulsion, as well as the phase ratio (Salager et al., 2001), as one phase is further dispersed in the continuous phase. This is similar to adding the dispersed phase to the continuous phase using a semibatch mode as described before. ...
Article
Emulsions are usually stabilised with a mixture of surfactants with different hydrophilicity. The initial partitioning of surfactants between the dispersed phase and continuous phase, and how these phases are brought into contact, can significantly affect the emulsification processes. Dynamic-phase behaviour maps were prepared to allow for a systematic investigation of the effects of emulsification routes on emulsion properties. Six semibatch modes of additions with constant surfactant concentration across the routes were selected. For a target cyclohexane-in-water emulsion using a pair of polyoxyethylene nonylphenyl ether surfactants with a specified HLB and water volume fraction, fine droplets could form only if water dissolving the water-soluble surfactant was added to the oil dissolving the oil-soluble surfactant. This route allowed the transitional inversion to occur and as a result fine droplets were formed due to an ultra-low interfacial tension. The addition of water dissolving the water-soluble surfactant to oil dissolving the oil-soluble surfactant, direct emulsification method, produced by far large droplets because of a rather high interfacial tension. In a series of experiment, the semibatch direct and phase-inversion emulsification method, were assimilated in situ. The impeller location was used as a variable that controls which phase is added as the dispersed phase. The location of impeller in relation to the interface did not affect the emulsion drop size at a high agitation rate, but it did at a low agitation rate. Under low agitation speed and when the impeller was placed in the oil phase, the oil layer progressively, but slowly, dragged the water phase and eventually inverted to an oil-in-water emulsion, indicating that transitional-phase inversion has locally occurred in the oil layer. At a high agitation speed the mechanical energy provided by the impeller homogenised the emulsion instantaneously and did not allow the optimum formulation and the associated ultra-low interfacial tension to be reached regardless of location of the impeller. A high impeller speed increased drop size by transforming the transition inversion mechanism to a catastrophic mechanism under which the size of drops is mainly determined by the mechanical energy provided. This paper aims to show how some of the complexities involved in emulsification processes can be explained by consulting with dynamic-phase maps.
... As soon as the emulsion is made, the HLD must be shifted away far from HLD=0, for instance by changing temperature or by changing formulation, in what may be called a quench process, one of the so-called unit operations in emulsion formulation engineering[60]. Very recent investigations indicate that local or transient stirring and mixing conditions may be used to affect the emulsion type[61], or to customize or fine tune the drop size distribution[53][54], as in the case of bimodal emulsions tailored to exhibit a particularly low viscosity and Newtonian rheological behavior, even at high internal phase content[62][63][64][65]. Even more complex cases are to be dealt with systems, which are emulsified by mass transfer or phase inversion[66][67][68], which is often associated to spontaneous emulsification[69]or with more or less retarded equilibration, depending on the formulation[70]. ...
... Después de una serie de pruebas preliminares en las que se varió la ubicación del impulsor: en la fase acuosa, en la interfase y en la fase aceite, se determinó que la misma sería justo debajo de la interfase, en la fase acuosa, con la finalidad de garantizar la obtención de emulsiones de tipo aceite en agua como se ha reportado en la literatura (Oldshue, 1990;Salager et al., 2001). ...
Article
Full-text available
Para la elaboración de emulsiones estables de aceite en agua (O/W) en la industria de alimentos se consideran generalmente una serie de variables físico-químicas relacionadas con la formulación y composición del sistema. Las condiciones de agitación y el protocolo de mezcla también influyen sobre el tipo y las características de las emulsiones obtenidas. Para lograr reproducibilidad bajo condiciones de operación industriales es posible correlacionar las propiedades de las emulsiones con las variables mencionadas. Investigaciones previas sostienen lo anterior para bajas proporciones de O:W. Sin embargo, en la industria de alimentos se trabaja a menudo con emulsiones de alto contenido de fase dispersa (>75%). Se estudió el proceso de producción de emulsiones concentradas de aceite de maíz en agua, utilizando un surfactante no iónico etoxilado. El método experimental se basó en el diseño factorial 23 con punto central, variando la relación másica aceite:agua, la velocidad de agitación, el tiempo de mezclado y la posición del agitador. Mediante análisis de regresión se halló una correlación logarítmica para predecir el diámetro promedio superficial (d32) de las gotas de la emulsión en función de proporción másica aceite:agua, tiempo y velocidad de agitación; esta última variable ejerció la mayor influencia. La correlación satisfizo los criterios fundamentales de independencia, homocedasticidad y distribución normal de los parámetros. La metodología de diseño puede ser empleada a nivel industrial para reducir la cantidad de ensayos a realizar y determinar la influencia estadística de las variables del proceso de mezclado sobre el diámetro promedio de las gotas de una emulsión.
... The vertical line location, as far as the WOR value is concerned, depends on the emulsification process, particularly the apparatus and the phase viscosities, as well as the method of mixing the oil and water phases [44,316]. ...
Preprint
Full-text available
Formulation is an ancient concept, although the word has been used only recently. The first formulations made our civilization advance by inventing bronze, steel, and gunpowder; then, it was used in medieval alchemy. When chemistry became a science and with the golden age of organic synthesis, the second formulation period began. This made it possible to create new chemical species and new combinations “à la carte.” However, the research and developments were still carried out by trial and error. Finally, the third period of formulation history began after World War II, when the properties of a system were associated with its ingredients and the way they were assembled or combined. Therefore, the formulation and the systems’ phenomenology were related to the generation of some synergy to obtain a commercial product. Winsor’s formulation studies in the 1950s were enlightening for academy and industries that were studying empirically surfactant-oil-water (SOW) systems. One of its key characteristics was how the interfacial interaction of the adsorbed surfactant with oil and water phases could be equal by varying the physicochemical formulation of the system. Then, Hansen’s solubility parameter in the 1960s helped to reach a further understanding of the affinity of some substances to make them suitable to oil and water phases. In the 1970s, researchers such as Shinoda and Kunieda, and different groups working in Enhanced Oil Recovery (EOR), among them Schechter and Wade’s group at the University of Texas, made formulation become a science by using semiquantitative correlations to attain specific characteristics in a system (e.g., low oil-water interfacial tension, formulation of a stable O/W or W/O emulsion, or high-performance solubilization in a bicontinuous microemulsion system at the so-called optimum formulation). Nowadays, over 40 years of studies with the hydrophilic-lipophilic deviation equation (HLD) have made it feasible for formulators to improve products in many different applications using surfactants to attain a target system using HLD in its original or its normalized form, i.e., HLDN. Thus, it can be said that there is still current progress being made towards an interdisciplinary applied science with numerical guidelines. In the present work, the state-of-the-art of formulation in multiphase systems containing two immiscible phases like oil and water, and therefore systems with heterogeneous or micro-heterogeneous interfaces, is discussed. Surfactants, from simple to complex or polymeric, are generally present in such systems to solve a wide variety of problems in many areas. Some significant cases are presented here as examples dealing with petroleum, foods, pharmaceutics, cosmetics, detergency, and other products occurring as dispersions, emulsions, or foams, that we find in our everyday lives.
... The vertical line location, as far as the WOR value is concerned, depends on the emulsification process, particularly the apparatus and the phase viscosities, as well as the method of mixing the oil and water phases [44,316]. ...
Article
Open access link: http://dx.doi.org/10.3390/encyclopedia2020054 Formulation is an ancient concept, although the word has been used only recently. The first formulations made our civilization advance by inventing bronze, steel, and gunpowder; then, it was used in medieval alchemy. When chemistry became a science and with the golden age of organic synthesis, the second formulation period began. This made it possible to create new chemical species and new combinations “à la carte.” However, the research and developments were still carried out by trial and error. Finally, the third period of formulation history began after World War II, when the properties of a system were associated with its ingredients and the way they were assembled or combined. Therefore, the formulation and the systems’ phenomenology were related to the generation of some synergy to obtain a commercial product. Winsor’s formulation studies in the 1950s were enlightening for academy and industries that were studying empirically surfactant-oil-water (SOW) systems. One of its key characteristics was how the interfacial interaction of the adsorbed surfactant with oil and water phases could be equal by varying the physicochemical formulation of the system. Then, Hansen’s solubility parameter in the 1960s helped to reach a further understanding of the affinity of some substances to make them suitable to oil and water phases. In the 1970s, researchers such as Shinoda and Kunieda, and different groups working in Enhanced Oil Recovery (EOR), among them Schechter and Wade’s group at the University of Texas, made formulation become a science by using semiempirical correlations to attain specific characteristics in a system (e.g., low oil-water interfacial tension, formulation of a stable O/W or W/O emulsion, or high-performance solubilization in a bicontinuous microemulsion system at the so-called optimum formulation). Nowadays, over 40 years of studies with the hydrophilic-lipophilic deviation equation (HLD) have made it feasible for formulators to improve products in many different applications using surfactants to attain a target system using HLD in its original or its normalized form, i.e., HLDN. Thus, it can be said that there is still current progress being made towards an interdisciplinary applied science with numerical guidelines. In the present work, the state-of-the-art of formulation in multiphase systems containing two immiscible phases like oil and water, and therefore systems with heterogeneous or micro-heterogeneous interfaces, is discussed. Surfactants, from simple to complex or polymeric, are generally present in such systems to solve a wide variety of problems in many areas. Some significant cases are presented here as examples dealing with petroleum, foods, pharmaceutics, cosmetics, detergency, and other products occurring as dispersions, emulsions, or foams that we find in our everyday lives.
... 16 The purpose of the present paper is to report the influence of the viscosity of both phases on the critical dispersed-phase fraction and on the mechanism of inversion, when a static inversion protocol is performed by continuously stirring an abnormal emulsion of the O/W type without adding any internal phase. These results complement previous studies on the influence of phase viscosity on the vertical branches of the standard inversion line, 3, [12][13][14] showing that there is a morecomplex pattern, particularly with respect to the occurrence of an intermediate multiple morphology. ...
Article
When the emulsion inversion from an abnormal oil-in-water (O/W) system to a normal water-in-oil (W/O) morphology is produced by continuous stirring, the fraction of dispersed phase at which the inversion is triggered (which is known as the critical dispersed phase fraction) and the inversion mechanism are affected by a change in viscosity. As the viscosity of any of the phases increases, the critical dispersed phase fraction decreases. When the oil phase has a similar or higher viscosity than the water phase, inversion occurs via the formation of a multiple emulsion w/O/W, in which the “W” external phase is continuously included as “w” droplets in the dispersed “O” phase drops. Hence, the apparent volume of the dispersed phase increases until a critical value is reached and the inversion is triggered. On the other hand, if the water phase is much more viscous than the oil phase, the experimental evidence suggests that the inversion occurs through the formation of a pseudo-fibrous structure, in which the connectivity of the internal phase is produced by drop elongation.
... A variação da W OR no sentido de aumentar a concentração deágua causa um decréscimo na salinidade da formulaçãoótima para este sistema modelo. Um resultado semelhante pode ser encontrado em SILVA et al. [193] e SALAGER et al. [184]. Para estes casos, a partição do surfactante favorávelà faseóleo se deve ao caráter lipofílico do n-pentanol. ...
Thesis
Generally, emulsions are formed when two immiscible liquids are subjected to agitation in presence of surfactants. Emulsion inversion is most of the times characterized by the continuous phase changing from water phase to oil phase or vice-versa. The emulsion systems were studied in terms of equilibrium and dynamic phase inversion by Conductometry and In Situ Near Infrared Spectroscopy NIR. It can be highlighted the originality in using NIR probe to track the phase inversion of complex emulsions. The tool provided properties and more knowledge about emulsions close to inversion. This allowed to evaluate the role of liquid crystals during phase inversion emulsification. The liquid crystal provides dynamic stability to emulsions during the transitional region of phase inversion. The second part of the thesis focused on systems containing petroleum, where a study about the influence of hydrate antiaggomerants in the formulation of waxy crude oil emulsions was performed. These chemicals act as emulsion hydrophilic surfactants. An apparatus of presssurized cell and a method to obtain petroleum conductivity for a large range of temperatures were also developed. The data provided by this apparatus may assist the operation and design of industrial electrocoalescers. \end{foreignabstract}
... The vertical line location, as far as the WOR value is concerned, depends on the emulsification process, particularly the apparatus and the phase viscosities, as well as the method of mixing the oil and water phases [44,316]. ...
Preprint
Full-text available
This is V1. There is a preprint V2 published on Researchgate
... At the same time, new phenomenological islands have been generated by specialists from the academic and industrial worlds who have concentrated their efforts in organizing the science and technological results from case by case studies into consistent phenomenologies with some degree of generality. This has resulted into an available know-how, so-called formulation engineering, which has been divided into unit operations [166], to efficiently solve problems and develop new applications [53,[167][168]. Unfortunately this know-how is not yet appropriately acquired and assimilated, particularly by people involved in industrial research and development activities. An extremely simple way to confirm this diagnostic is to notice that a large majority of people formulating with surfactants in many different applications are still using the 60-year-old HLB as the only classification for their products, when a more performing approach has been readily available for at least the past two decades, according to what has been said by famous lecturers in congresses [169][170], and has boosted the research and development performance of people who use it. ...
Chapter
Full-text available
A molecular dynamics simulation of a chemical trapping probe, 4-hexadecyl-2,6-dimethylbenzenediazonium ion, nestled in a cross section of micelle composed of decanediyl-α,ω-bis (dodecyldimethylammonium chloride) or 10-2-10 2Cl (aggregation number = 27). Depicted are chloride ions (red), a spaghetti-like core of decyl tails (golden yellow), gemini nitrogens (steel blue), and the chemical probe with carbons (cyan), hydrogens (white), and diazonio group (dark blue). For esthetic purposes, various groups in the gemini micelle cross section are not quite to scale. (Examples of probe applications: X.
... This is a consistent mechanical influence which has been explained in absence of formulation preference by a higher momentum transfer in the more viscous phase [27].These viscosity effects on the vertical parts of the standard inversion line in Fig. 2 could be extremely important in some cases [26]. The type and location of the stirring device have also some influence [28,29]. ...
Article
The addition of water to hydrophobic alkyd resin containing a hydrophilic nonionic surfactant (polyethoxylated-20-oleyl alcohol) was used to produce the emulsion morphology change from W/O to O/W in a small thermostated reactor (50 mL). The so-called catastrophic phase inversion of the water/alkyd resin system was detected by monitoring both, the viscosity by torque measurement and the electrical conductivity, until an equal weight fraction of water and resin is attained (fw = 0.5). The two methods provide similar values of the phase inversion point (PIP). Although the determination of the PIP exhibits a small inaccuracy, it is clear that different torque profiles and PIP are observed depending on the resin neutralization level, the surfactant concentration and the water addition rate. For the non-neutralized resin, both, PIP and emulsion drop size, decrease with surfactant concentration increase. The completely neutralized resin could be emulsified using a minimum of 2 wt% of surfactant in the final emulsion. In such a case the water fraction at which inversion occurs (fw,Inv = 0.36) is independent of the surfactant concentration and a small resin drop diameter (< 200 nm) can be obtained. A more precise study of the reached drop size of the emulsion versus resin neutralization (0, 25, 50, 75, 100 and 125%) indicates that a minimum diameter is obtained around 90-100% neutralization, with no effect of over-neutralization. For non-neutralized resin a maximum fw,Inv (0.25) can be obtained by reducing water addition rate allowing the production of 0.5 μm droplets in a longer process.
... Further, by performing a formulation scan represented by the vertical arrow in Fig. 1 (it can be done by increasing temperature or electrolyte content, for example), some emulsion properties change as depicted in Fig. 2. In the latter, trends in interfacial tension, drop size and viscosity are shown along the formulation scan. It has also been found (Salager et al., 2003(Salager et al., , 2001a) that varying stirring energy and impeller position can produce a narrowing or widening of the A region. Thus, mixing at low speeds widens the A region meaning that very concentrated O/W or W/O emulsion can be produced, although these emulsions tend to be rather unstable. ...
Article
Parenteral emulsions are special O/W emulsions used to feed patients whose medical condition makes them unable to eat normally. Therefore, parenteral emulsions must comply with several specifications. One is that the maximum droplet size must be below 5μm in order to avoid the risk of a pulmonary embolism. In this work, we describe the step-by-step procedure followed to simplify a current industrial recipe by applying recently developed principles under the name of formulation engineering. Both hydrodynamic and physicochemical formulation parameters were manipulated to reduce energy input and equipment requirements. The current process consists of two heating steps, three mixing stages and filtering to eliminate droplets larger than 5μm. The mixing stages require first an agitated tank for the making of a coarse dispersion, then a high-speed mixer and last a two-stage homogenizer. Despite the intensive mixing the emulsion does not comply with droplet size specifications and filtering is necessary. Our procedure requires heating once and then two mixing stages, the first to produce a coarse dispersion and the second to refine droplet size in a conventional agitated tank. Further, no filtering is necessary since no droplets larger than 3μm are produced in the mixing tank. The parenteral emulsions resulting of this simplified and less energy intensive process complies with droplet size requirements and are stable over several months.
... The use of block poly(ethylene oxide) (PEO)-poly(propylene oxide) (PPO) polymers as a kinetic stabilizer of the outer emulsion has been reported, [9][10][11] but very few studies have dealt with the protocol of emulsification for producing a multiple emulsion. 12 Because the protocol has to do with the order of introduction of the different substances, it can cause delays and other kinetic effects favorable or not to the end target of stabilizing the multiple emulsion. The aim of the present paper is to report a novel approach for making a multiple w/O/W emulsion using a surfactant-polymer mixture and two different emulsification protocols. ...
... Beware, however, that a very high shearing with an already viscous emulsion could move the vertical inversion line. Even the position of the stirrer in the mixing volume could be important, and could reduce the zone of normal emulsion in the formulation-WOR map [169], which is often an inconvenience. Nevertheless, it is not always the case, because a produced emulsion could be too viscous with 90% of internal phase. ...
Article
Full-text available
The effects of surfactant molecules involved in macro-, mini-, nano-, and microemulsions used in cosmetics and pharmaceuticals are related to their amphiphilic interactions with oil and water phases. Basic ideas on their behavior when they are put together in a system have resulted in the energy balance concept labeled the hydrophilic-lipophilic deviation (HLD) from optimum formulation. This semiempirical equation integrates in a simple linear relationship the effects of six to eight variables including surfactant head and tail, sometimes a cosurfactant, oil-phase nature, aqueous-phase salinity, temperature, and pressure. This is undoubtedly much more efficient than the hydrophilic-lipophilic balance (HLB) which has been used since 1950. The new HLD is quite important because it allows researchers to model and somehow predict the phase behavior, the interfacial tension between oil and water phases, their solubilization in single-phase microemulsion, as well as the corresponding properties for various kinds of macroemulsions. However, the HLD correlation, which has been developed and used in petroleum applications, is sometimes difficult to apply accurately in real cases involving ionic–nonionic surfactant mixtures and natural polar oils, as it is the case in cosmetics and pharmaceuticals. This review shows the confusion resulting from the multiple definitions of HLD and of the surfactant parameter, and proposes a “normalized” Hydrophilic-Lipophilic Deviation (HLDN) equation with a surfactant contribution parameter (SCP), to handle more exactly the effects of formulation variables on the phase behavior and the micro/macroemulsion properties.
... 19,28,29 This direction of change corresponds to the industrial emulsification of viscous oil phases, e.g., polyester resins, in water and may thus be influenced by the high viscosity of the oil phase which is known to favor the O/W morphology, as indicated by the shift in one or the two vertical branches of the inversion line. 30,31 In the present case, the oil and water phases have essentially the same viscosity and the abnormal to normal inversion is carried out in the two possible cases of abnormal emulsions, i.e., at HLD > 0 (C + f A + ) and at HLD < 0 (Bf A -). The conditions were particularly selected here to return useful experimental data on the HLD > 0 (C + f A + ) case, on which there is no previous report. ...
Article
The rate of addition of the internal phase influences the catastrophic inversion of emulsions in the direction of change from abnormal to normal morphology. At a low addition rate, the inversion takes place after a small amount of the internal phase is added, and it happens through the occurrence of multiple emulsion morphology. At a high addition rate, the inversion appears to be delayed, and it takes place without the occurrence of a multiple emulsion.
... For the stability of emulsions, there are two main mechanisms that are responsible for providing colloidal stability: steric and electrostatic stabilization, which are created through adsorption of surfactants, polymers, or fine solids onto the droplet interface [6]. Several approaches have been proposed to explain the surfactant's role in the past 50 years, such as Griffins' Hydrophile Lipophilic Balance (HLB) [7], Winsor's R ratio, Shinoda's phase inversion temperature (PIT) [8,9] and the more recent expression proposed by Salager [10,11], which resorts to the surfactant affinity difference (SAD) or its dimensional equivalent hydrophilic-lipophilic deviation (HLD). Indeed, the emulsion stability is affected by many terms and conditions including temperature, electrolyte concentration, oil composition, surfactant type and concentration. ...
... Very recent investigations indicate that local or transient stirring and mixing conditions may be used to affect the emulsion type [61], or to customize or fine tune the drop size distribution [53][54], as in the case of bimodal emulsions tailored to exhibit a particularly low viscosity and Newtonian rheological behavior, even at high internal phase content [62][63][64][65]. Even more complex cases are to be dealt with systems, which are emulsified by mass transfer or phase inversion [66][67][68], which is often associated to spontaneous emulsification [69] or with more or less retarded equilibration, depending on the formulation [70]. ...
Article
Full-text available
The emulsification yield, i. e., the reduction of drop size when a surfactant-oil-water system is stirred, can be altered by changing: 1) the physicochemical formulation variables which are linked to the nature of the water, oil, and emulsifier, 2) the composition variables (surfactant concentration and water- to-oil ratio) and 3) the variables which characterize the mechanical energy supplied by the stirring device. After reporting the general trends found in previous research, the best compromise situations to attain a minimum drop size are located in a three dimensional formulation-composition-stirring space.
... The way the phases are mixed becomes crucial to favor one or the other type of dispersion independently of the formulation, [45] and the global or local WOR value is the key to establish the emulsion morphology in some processes and with particular devices. [46] When the formulation and composition effects are in conflict, e.g., the formulation would favor an O/W emulsion but there is only 10% of W which cannot be made the external phase, then double or multiple emulsions are formed with droplets in drops. ...
... The way the phases are mixed becomes crucial to favor one or the other type of dispersion independently of the formulation, [45] and the global or local WOR value is the key to establish the emulsion morphology in some processes and with particular devices. [46] When the formulation and composition effects are in conflict, e.g., the formulation would favor an O/W emulsion but there is only 10% of W which cannot be made the external phase, then double or multiple emulsions are formed with droplets in drops. ...
Article
Three protocols are tested to invert an abnormal emulsion into a normal one: a dynamic process with continuous addition of an internal phase, continuous stirring of a given emulsion with no addition of an internal phase, and the combination of the previous ones, i.e., a standstill dynamic process in which the addition of an internal phase is interrupted at some time and then followed by continued stirring. In situ follow-up of both conductivity and viscosity data in a rheomixer vessel provides complementary information to corroborate the critical dispersed-phase concept as a condition for the inversion to take place in all cases. Some applications are discussed.
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Emulsification processes results in the generation of droplets populations produced from the dynamic equilibrium between the breakup and coalescence phenomena determined primarily by the formulation and composition variables, mixing characteristics and emulsion preparation. The information contained in the UV-vis spectrum on the absorption and scattering properties of the emulsions lead to the interpretation of the spectra in terms of the particle size distribution, the particle shape, and the chemical composition of the oil and emulsifier. This article reports analysis of emulsions on transmission spectrum as function of the oil concentration and physicochemical variables. The quantitative interpretation of the transmission spectrum is performed in the portion where no absorption is present (300-820 nm) leading to reliable estimated of droplet size populations in the range of 1 to 20 µm. The possibility of obtaining information from a single multiwavelength measurement makes UV-vis spectroscopy a powerful tool for characterization of dispersed systems.
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The stirring intensity has a complex effect on the catastrophic inversion of emulsions in the direction of change from abnormal to normal morphology. At both low and high stirring energy, the inversion takes place early, after a low amount of the internal phase is added and through the occurrence of a multiple emulsion. At some intermediate stirring energy, the inversion appears to be delayed and it takes place without the occurrence of multiple emulsions.
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The properties of the emulsions can be described by the droplet size distribution, which gives a statistical inventory of the dispersed phase fragmentation. This research reports measurements of droplet size distribution from multiwavelength transmission data and estimated of droplet size from electron microscope/osmium tetroxide technique. The quantitative interpretation of the transmission spectrum is performed in the spectral range (300–820 nm) leading to reliable estimated of droplet size populations in the range of 1–20 µm as function of the monomer concentration. The measurements reported are fast, highly reproducible and potential applicable to emulsification and polymerization processes.
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The preparation of double water-in-oil-in-water (W/O/W) emulsions containing xanthan gum (XG) in the absence of hydrophilic surfactant was investigated. The emulsions were prepared by the two-step emulsification process. The stability of these systems was evaluated through the evaluation of physicochemical and rheological properties. Microscopic observations in combination with particle size analysis were also performed. The obtained results show that it is possible to prepare stable double emulsions with a single polysaccharide by using the indirect process. The stability depends on the viscosity of the continuous phase and hence the concentration of XG. The apparent viscosity of the emulsions increased with the increase of XG concentration. Particle size analysis shows that the droplet sizes are directly related to XG concentration.
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In emulsification processes, the estimation of the droplet size distribution is important data not only because it is linked with the manufacturing process, but also because it is an important parameter affecting the emulsion stability. The aim of this research is to use the ultraviolet-visible transmission spectrum as a tool for emulsion characterization (droplet size and stability) to be a function of monomer concentration, and to verify of emulsion stability using the volume of separated phase's technique. Both techniques are applied to monomer emulsions as a function of emulsifier concentration. Results show correlations between droplet size measurements and stability of emulsions using the spectroscopy technique; results were also found to be in agreement using the cleared volume method.
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Phase inversion is the process in which emulsion oil-in-water (O/W) is transformed to water-in-oil emulsion (W/O). There are two types of emulsion inversion. The first one is based on the variation of the system formulation and is called transi- tional inversion whereas the second one, which takes place when the water/oil ratio is changed, is so -called catastrophic inversion. The latter, depends on the stirring energy and duration, as well as on the viscosity, as well as the viscosity of the oil phase. The present study reports the effect of an increase of aqueous phase viscosity by adding an anionic polymer (car- boxymethylcellulose sodium salt) on phase behavior and standard inversion boundary. The effect of the stirring energy is also reported. The results indicate that the addition of carboxymethylcellulose alters the formulation, which results in varia- tions in phase behavior and standard inversion boundary. It is shown that an increase of the aqueous phase viscosity pro- duces a considerable increase in the three phase's region in the equilibrated systems until a viscosity of 0.5 Pas is attained, with an insignificant increase on this zone between 0.5- 1Pa.s. An increase in the viscosity of the aqueous phase also shifts the catastrophic branch of the standard inversion line, hence reducing the region of O/W emulsions for viscosities lower than 0.5 Pa.s. and this line keeps constant for higher viscosities.
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Emulsion inversion is a complex phenomenon, often perceived as an instability that is essentially uncontrollable, although many industrial processes make use of it. A research effort that started 2 decades ago has provided the two-dimensional and three-dimensional description, the categorization and the theoretical interpretation of the different kinds of emulsion inversion. A clear-cut phenomenological approach is currently available for understanding its characteristics, the factors that influence it and control it, the importance of fine-tuning the emulsification protocol, and the crucial occurrence of organized structures such as liquid crystals or multiple emulsions. The current know-how is used to analyze some industrial processes involving emulsion inversion, e.g. the attainment of a fine nutrient or cosmetic emulsion by temperature or formulation-induced transitional inversion, the preparation of a silicone oil emulsion by catastrophic phase inversion, the manufacture of a viscous polymer latex by combined inversion and the spontaneous but enigmatic inversion of emulsions used in metal working operations such as lathing or lamination.
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Oil-in-water emulsion is an innovate manner by which heavy crude oil can be transported from producing sites to transforming sites through pipelines. The effect of emulsifier on the interfacial properties and demulsification performance of demulsifier for heavy crude oil–in-water emulsion has been studied by many researchers. However, the influence of asphaltene in heavy crude oil on the interfacial properties of demulsifier has not been investigated yet. In this article, the influence of asphaltene concentration of two typical demulsifiers (straight-chained SP-1 and branch-chained AE-1) was systematically studied in terms of absorption thermodynamics, absorption kinetics, and coalescence kinetics. The results revealed that the demulsifier adsorption was a ΔS controlled spontaneous process. The absolute value of ΔG of SP-1 adsorption was found to decrease with asphaltene concentration, whilst the asphaltene concentration had no significant influence on that of AE-1. With the increase of asphaltene concentration, the demulsifiers’ adsorption rates increased, but the reorganization rates on the interface decreased. Coalescence speed of asphaltene droplet decreased with asphaltene concentration in spite of demulsifier type. Additionally, AE-1 had higher absolute value of ΔG, adsorption speed, and coalescence speed than that of SP-1 at the same condition.
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In order to make stable oil in water (O/W) emulsions at the food industry, it is usually considered a series of physico-chemical variables related with formulation and composition of the system. Mixing conditions and mixing protocol also influence on the type and characteristics of resulting emulsions. To achieve reproducibility under industrial operation conditions it is possible to correlate the properties of the emulsions to the variables mentioned above. Previous research sustain the last for low O:W relations. However, food industry frequently uses high dispersed phase content emulsions (greather than 75%). The process for the production of concentrated corn oil in water emulsions was studied using a non-ionic ethoxilated surfactant. Experimental method was based on a Factorial Design 23 with central point, varying: oil:water mass ratio, agitation speed, mixing time, and impeller position. It was used a regression analysis in order to obtain a logarithmic correlation to predict surface mean drop diameter (d32) of the emulsion in function of: oil:water mass ratio, mixing time and agitation speed; the strongest effect was due to the last one variable. The correlation satisfied the fundamental criteria of independence, homocedasticity, and normal distribution of parameters. Design methodology can be employed at industrial level in order to reduce the assays quantity to be performed and also to determine the statistical influence of process variables on mean drop diameter of the emulsion.
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Screening optimum formulation for surfactant flooding is usually time consuming, and correctly modeling microemulsion phase behavior is critical for chemical flooding simulation. This paper extends the physics based Hydrophilic Lipophilic Difference (HLD) Net Average Curvature (NAC) model, and comprehensively demonstrated its capabilities in predicting the optimum formulation and microemulsion phase behavior. This paper uses quantitatively characterized HLD parameters, accurately predicted four optimum surfactant formulations for a target reservoir. This paper measured surfactant head area of extended surfactants and further predicted the equilibrium interfacial tension of four phase behavior test. Comparing to the empirical Hand's rule phase behavior model, the HLD-NAC equation of state shows great advantages in helping formulation design and modeling microemulsion phase behavior. Surfactant flooding sandpack laboratory tests are also interpreted by UTCHEM chemical flooding simulator coupled with the HLD-NAC phase behavior model. The results indicate the significance of HLD-NAC equation of state in not only shorten the surfactant screening processes for formulators, but also predicting microemulsion phase behavior based on surfactant structure. A compositional reservoir simulator with such an equation of state will increase its predictability and hence help with the design of surfactant formulation.
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The precipitation of wax crystals in water-in-crude-oil emulsion impairs the safety and economy of multiphase transportation in oil fields. At present, there are different opinions on the precipitation modes of paraffin wax. Existing studies mostly use microscopic observation to determine whether wax crystals are adsorbed at the oil–water interface. In this study, the precipitation modes of paraffin wax in water-in-model-oil emulsions were comprehensively investigated by combining calorimetry, drop shape analysis, and rheology. It was found by differential scanning calorimetry that the presence of water droplets could slightly increase the wax precipitation temperature (WPT), reflecting the function of the interface as nucleation sites. Further, by adopting the drop shape analysis experiment and calculating the interfacial tension and interfacial dilational modulus based on it at the temperatures above and below the WPT, it was confirmed that wax crystals did adsorb at the interface and forced the interface to solidify, causing the interface to wrinkle when shrinking. Then, the results of the bulk viscoelasticity test proved the precipitation of wax crystals in the continuous oil phase and the formation of a network structure, which made the emulsion gelatinize and show strong viscoelasticity and yield characteristics. Finally, it was concluded that wax crystals not only precipitate in the oil phase but also precipitate and adsorb at the interface.
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This study was development of mayonnaise was carried out at the Parul university of Applied Sciences, Parul University, Vadodra. Traditional mayonnaise is manufactured with soybean oil (SBO) and egg-yolk containing ingredients. Flaxseed oil, a healthy lipid source, has cholesterol-lowering effects, and could be used to replace SBO in mayonnaise preparation. To take advantage of the health benefits associated with flaxseed oil, food products containing flaxseed oil need to be developed and characterized. Mayonnaise-type spreads containing flaxseed oil were developed using a constrained mixture design. The quality of the mayonnaise was characterized through the development of sensory descriptors and determination of several physicochemical properties. A sensory descriptive language was developed that covers a lexicon that can potentially be used for a detailed descriptive analysis. Color, pH and viscosity. Its specifications were effectively determined Color parameters were not changed with time. pH was found to be directly proportional to Skimmed milk powder content in the product and did not change over time. Mayonnaise-type spreads containing flaxseed oil and skimmed milk powder concentrate was successfully developed.
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Emulsion inversion is a complex phenomenon, often perceived as an instability that is essentially uncontrollable, although many industrial processes make use of it. A research effort that started 2 decades ago has provided the two-dimensional and three-dimensional description, the categorization and the theoretical interpretation of the different kinds of emulsion inversion. A clear-cut phenomenological approach is currently available for understanding its characteristics, the factors that influence it and control it, the importance of fine-tuning the emulsification protocol, and the crucial occurrence of organized structures such as liquid crystals or multiple emulsions. The current know-how is used to analyze some industrial processes involving emulsion inversion, e.g. the attainment of a fine nutrient or cosmetic emulsion by temperature or formulation-induced transitional inversion, the preparation of a silicone oil emulsion by catastrophic phase inversion, the manufacture of a viscous polymer latex by combined inversion and the spontaneous but enigmatic inversion of emulsions used in metal working operations such as lathing or lamination.
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The bidimensional fornulation-water/oil ratio map is used to characterize the emulsion properties and the transitions which occur when the inversion line is crossed.Conductivity, stability and viscosity data show that there exist four regions, each corresponding to a class of emulsion, So-called A B and A C conditions produce normal W/0 and 0/W stable emulsions, while the B and C cases lead to multiple emulsions.The transitional and catastrophic inversions are found to correspond to quite different transitions.
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A screening test used to help select surfactant systems potentially effective for oil recovery is to identify those formulations that yield middle-phase microemulsions when mixed with sufficient quantities of oil and brine. A correlation is presented to link these variables regarding their presented to link these variables regarding their contributions to middle-phase formation: structure of the sulfonated surfactant, alkane carbon number (ACN), and alcohol type and concentration. WOR and temperature effects are introduced as correction terms added to the empirical correlation.Sets of variables that give middle-phase microemulsions are shown as identical to those defining the low tension state without observable middle phases. This generally occurs for low surfactant phases. This generally occurs for low surfactant concentrations. Introduction Healy and Reed and Healy et al. have shown that the phase behavior of surfactant/brine/oil systems is a key factor in interpreting the performance of oil recovery by microemulsion performance of oil recovery by microemulsion processes. By systematically varying salinity, processes. By systematically varying salinity, they found low interfacial tensions and high solubilization of both oil and water in the microemulsion phase to occur in or near the salinity ranges giving phase to occur in or near the salinity ranges giving three phases. Since both low interfacial tensions and a high degree of solubilization are considered desirable for oil recovery, the conditions for three-phase formation assume added importance. Similar conclusions have been reported in other recent papers.Several investigators have considered the effect of different variables on the range of salinities for which three phases form. This optimum salinity (a more precise definition is given in a subsequent section) has been found to decrease with increasing surfactant molecular weight, and to increase with increasing chain length of the alcohol cosurfactant. Studies on the effect of alcohols by Jones and Dreher and Salter provided results similar to those reported by Hsieh and Shah.The interfacial tension at surfactant concentrations low enough so that a discernible third phase does not form has been the subject of considerable phase does not form has been the subject of considerable investigation regarding surfactant molecular weight and structure, oil ACN, salinity and surfactant concentration, and alcohol addition. A recent paper was a first attempt to tie together the low paper was a first attempt to tie together the low tension state observed at low surfactant concentrations and the three-phase region observed at higher surfactant concentrations. All indications point to an inextricable intertwining of phase point to an inextricable intertwining of phase behavior, surfactant partitioning, solubilization, and low tensions. This paper corroborates the equivalence of three-phase behavior and minimum tension as criteria for optimum formulation and presents a correlation that quantifies the trends presents a correlation that quantifies the trends observed previously. EXPERIMENTAL Aqueous phases containing surfactant, electrolyte (NaCl), and alcohol were contacted with an oil phase by shaking and allowed to stand until phase phase by shaking and allowed to stand until phase volumes became time independent for 2 days. All concentrations are expressed in grams of chemical per cubic centimeter of aqueous phase (g/cm3) per cubic centimeter of aqueous phase (g/cm3) before contacting with the hydrocarbon phase. Unless otherwise noted, the oil phase represents 20% of the initial total volume. All measurements, unless otherwise noted, were conducted at room temperature (25 plus or minus 1 degrees C). SPEJ p. 107
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The inversion locus is represented on a generalized mixed bidimensional scan (formulation-WOR), where the formulation variable may be the salinity, oil ACN, alcohol type or concentration, surfactant parameter such as EON, or temperatureAt near unity water/oil ratio the inversion locus (Phase Inversion Formulation: PIF) approximately matches the optimum formulation for minimum tension and phase behavior. In this region the inversion depends essentially upon physico-chemical factors. At extreme water/oil ratios, the inversion locus depends essentially upon the volumetric proportions of the phases, i.e., a physical factorA general classification of emulsion type is proposed according to the optimum formulation and phase inversion linesThe alterations of the inversion locus with surfactant type, oil viscosity and conditions of emulsification, are discussed.
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A systematic relationship was found between the equilibrium phase behavior of a surfactant-alcohol-oil-water system and the type and stability of the corresponding emulsion.Formulations are scanned through the three phase transition by changing (one at the time) brine salinity, oil EACN, surfactant nature and alcohol concentration. Whatever the scanning variable, it is found that the electrical conductivity exhibits a large change near the optimum formulation, indicating the inversion of the continuous phase of the dispersed system.On the other hand, the emulsion stability is found to undergo a deep minimum for formulations corresponding to the three phase behavior at equilibrium.The large but relatively smooth variation of the conductivity gives some hints on the possible continuity structure of the MOW triphasic emulsions.
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The phase behavior of surfactant-water-viscous oil systems is studied as well as the properties of the corresponding emulsions. The oil viscosity is increased up to 1000 cP by using different hydrocarbon mixtures. This change implies a variation in the Equivalent Alkane Carbon Number (EACN), which is compensated in order to maintain a comparable formulation.When the oil viscosity increases, the A+ region, which exhibits stable w/o emulsions with medium to high internal phase ratio, tends to shrink, and finally vanishes when the viscosity exceeds 50-100 cP; the inversion line on a formulation-WOR map exhibits a shift of its A+/C+ branch; the remaining of the inversion line, as well as the general phenomenology concerning the emulsion properties, still follows the patterns found with light hydrocarbons.
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Catastrophe theory, in particular the elementary cusp catastrophe, has been successfully applied to describe the qualitative features of catastrophic phase inversion in emulsions, but quantitative, experimental tests of the cusp catastrophe did not yield satisfactory results. We have shown that the elementary butterfly catastrophe can fit experimental data from the literature with reasonable accuracy. The quality of the fit may be improved, but only at the cost of the introduction of more fit parameters with little or no physical significance. We present an expression derived from physical properties rather than mathematical ones, on the basis of which all observed catastrophic phenomena can be qualitatively described. At values of the interfacial tension typical to coarse emulsions, this model predicts phase separation. However, phase inversion is generally observed under these conditions. We point out that the assumptions that justify a thermodynamical treatment of transitional inversion are not valid for catastrophic inversion. Our conclusions indicate that catastrophic phase inversion, unlike transitional inversion, should be treated on a kinetic basis rather than a thermodynamical one.
Article
Thesis (M.S.)--Ohio State University. Bibliography: leaves 70-72.
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The Gibbs free energy of an amphiphile-oil-water system may be represented by the potential of the fourth, so-called butterfly, elementary catastrophe. This potential is a sixth degree polynomial of a single state variable, and depends of four control, i.e., observable variables. It is shown that the bifurcation of this catastrophe, i.e., the projection of the degenerate critical points of the potential on the control space, matches the classical Winsor's diagram representation of the phase behavior of the ternary systems. Control variables are surfactant concentration, water-to-oil ratio, deviation from optimum formulation, and a parameter characterizing the quality of the system; the state variable is related to phase density.
Article
The phase volume at which emulsion phase inversion takes place is dependent on the degree of agitation. Under conditions of vigorous agitation, there is a relationship between the inversion point and the phase diagram of the oil + water + emulsifier system. The emulsion morphology is determined by the thermodynamic behavior of the homogeneous unstable fluid mixture. Spinodal decomposition provides the link between emulsion structure and nonequilibrium thermodynamics.
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The main features of the dynamic inversion of emulsions containing anionic surfactants are discussed after two experimental formulation-water/oil composition maps. Emulsions inverting under dynamic conditions follow the well-known inversion patterns for equilibrated systems, but at extreme water/oil ratios the dynamic inversion locus— where the so-called catastrophic inversion takes place-depends not only upon the volumetric proportion of the phases, but also on the direction in which this proportion is changed, therefore resulting in a hysteresis phenomenon.The hysteresis zone is shown to depend upon other factors, i.e. formulation and surfactant concentration. The hysteresis band widens as the formulation departs from optimum. On the other hand, an increase in surfactant concentration also widens the hysteresis zone and shifts it away from the unity water/oil ratio, therefore producing emulsions with an even higher internal phase ratio.
Article
Bancroft's rule of thumb that a surfactant which preferentially partitions into water favors the formation of oil-in-water (O/W) emulsions and that a surfactant which preferentially partitions into oil favors the formation of water-in-oil (W/O) emulsions has been known for some 80 years. Although by judicious control of the emulsification process one can generate exceptions, the rule of thumb often works well. It was not, however, until Griffin's famous paper of 1949 that an attempt was made to quantify the emulsifying tendency of a surfactant. Griffin observed that certain combinations of the surfactant hydrocarbon and ethylene oxide chain lengths favored O/W or W/O emulsions. In the paper he noted that the emulsion chemist will choose a water-soluble surfactant to make an O/W emulsion and an oil-soluble one to make a W/O emulsion. To try to put this principle of hydrophile—lipophile balance (HLB) on a quantitative footing, he introduced the concept of an HLB number. According to Griffin, the HLB is the balance of the size and strength of the hydrophilic and lipophilic moieties of a surfactant molecule. The HLB number was based on the molecular groups composing the surfactant. According to this concept, the optimal surfactant for a desired emulsion of a given oil can be chosen by a simple calculation from a look-up table.
Article
The stability of water-in-oil-in-water (W/O/W) multiple emulsions was investigated using rheological measurements, droplet size analysis and optical microscopy. Both steady state and oscillatory measurements were carried out simultaneously. The W/O/W emulsion was prepared using a lipophilic surfactant mixture (triglycerol triricinoleate and sorbitan monooleate) and an ABA block copolymer of poly(ethylene oxide)—poly(propylene oxide) (Synperonic PEF127). The composition of the lipophilic surfactant mixture was investigated and it was shown that the triglycerol triricinoleate alone or with small additions of sorbitan monooleate gave the best stability. The effect of the Synperonic PEF127 concentration was investigated using rheological measurements as well as droplet size analysis. This showed that the PEF127 concentration should not exceed 1.2%; otherwise some oil-in water emulsion droplets are produced within the multiple emulsion. Optical microscopy investigations confirmed the results obtained using rheology and droplet size analysis. A multiple emulsion with optimum composition of surfactants remained stable for 223 days at room temperature. The results of these investigations demonstrated that very stable multiple emulsions could be produced provided the system is optimised. The rheological measurements provided a powerful tool to investigate the stability without the need of diluted systems.
Article
In agitated liquid—liquid dispersions, catastrophic phase inversions (in which water-in-oil emulsions are transformed into oil-in-water emulsions) have been induced by changes in the phase ratio. Drop size distribution during catastrophic phase inversion was found to depend on stirring speed and on the addition rate of the aqueous phase. The formation of oil-in-water-in-oil drops and the choice of surfactant are important. A wide range of phase ratios was used in the experiments and changes in drop sizes (and in drop size distributions) were determined throughout the phase inversion. A number of different drop formation mechanisms which are compatible with the experimental results are proposed. Quantitative relationships between drop sizes, stirrer speed and phase ratio are obtained for a wide range of phase ratios. Coalescence mechanisms are related to energy balances for the dispersions. Drop sizes in the inverted emulsions are compared with sizes which can be obtained by direct emulsification. Smaller drops are produced by direct emulsification because drop coalescence is less important than is the case with catastropic inversion.
Article
Multiple emulsions, especially water-in-oil-in-water (W/O/W) type systems, have potential applications for the formulation and processing of foods, drugs, cosmetics, etc, as each dispersed globule in this type of emulsions consists of liquid compartments separated from the same liquid suspending medium by a thin layer of another immiscible liquid components. This article reviews a series of fundamental works on the formation and dispersion state of multiple emulsion systems and integrates advances made in the area of colloid science so as to obtain further insights into the formulation of W/O/W emulsions. The contents are divided into three sections: methods for preparing multiple emulsions in view of the phase diagram of mixed components, dynamic aspects of oil layer in W/O/W emulsions, and stability of this type of emulsions.
Article
The effect of stirring energy upon the characteristics of dynamic emulsion inversion is discussed on an experimental formulation–composition map for emulsions containing an anionic surfactant. It is shown that a vigorous agitation promotes the early inversion of high internal phase ratio emulsions. The hysteresis zone narrows and moves to an intermediate position within the ambivalent region that is attained for lower stirring speeds. A simple explanation based on the catastrophic inversion model is proposed to interpret these features.
Article
An attempt was made to provide a basic composition and simple technique for preparing the W/O/W emulsions in an edible form in a view to possible food applications of this type of emulsions. It has been found that TGCR (tetraglyceryl condensed ricinoleate), which is one of the hydrophobic food surfactants, plays a relevant role in developing water/olive oil/water emulsions due to the phase inversion phenomenon occuring when an aqueous solution of glucose or sodium chloride or acetic acid is being introduced successively into the mixture of TGCR and olive oil. The existence of a small amount of sodium chloride (around 10 mM) in the aqueous phase facilitated the development of a water/olive oil/water-type dispersion. The durability of oil layer on the surface of the aqueous compartments in the W/O/W emulsions prepared was much improved by addition of sodium chloride to the aqueous phase.
Article
A short review of the experimental findings concerning the stabilization of emulsions by solid particles is given. We then describe the preparation and properties of water-in-oil (w/o) emulsions stabilized by nanometer-sized hydrophobic silica particles alone. Emulsions of median diameter equal to 0.6 μm are completely stable to coalescence as a result of an adsorbed layer of particles at the oil−water interface. Their stability to sedimentation increases with particle concentration due to network formation of the particles in the continuous oil phase. The w/o emulsions catastrophically invert, without hysteresis, to oil-in-water (o/w) at volume fractions of water around 0.7, i.e., as soon as the drops begin to deform. The drops in o/w emulsions are larger (100 μm) and cream rapidly but remain stable to coalescence. We demonstrate that for emulsions stabilized by hydrophilic silica particles, phase inversion from o/w to w/o occurs at the same dispersed phase volume fraction as above. It is therefore suggested that the system hydrophile−lipophile balance is determined by the particle wettability. Comparisons with the behavior of surfactant-stabilized emulsions are given throughout.
Article
The partitioning coefficient of a surfactant between oil and water is related to the free energy of transfer from one phase to the other. The influence of temperature on the partition coefficient of octylphenol ethoxylate oligomers between oil and water is reported. The variation of the partition coefficient with formulation variables can be used as a yardstick for the concept of generalized formulation expression.
Article
This paper encompasses classic trends as well as recent advances in the understanding of emulsion inversion phenomena. The generalized formulation issue is first discussed from hydrophilic−lipophilic balance to the most recent concepts. The so-called standard inversion line on the formulation−composition map exhibits several branches, referred to as transitional and catastrophic inversions, that bound normal and abnormal emulsion regions. Dynamic inversion is also discussed with its hysteresis zones, where both types of emulsions may be attained, depending upon the system's previous history of the formulation−composition map. Recent findings are reported concerning the effect of variables with practical relevance (i.e., stirring energy, viscosity of phases, surfactant concentration, and partitioning) on the standard and dynamic inversion patterns. State-of-the-art emulsion inversion modeling is briefly discussed.
Article
Factors that affect control over which of two immiscible liquids would be continuous in stirred tanks were studied. Variables that were investigated were viscosities, densities, speed of mixing, manner of initiating the dispersion, and the materials and construction of the mixing apparatus.It was found that for a given liquid pair there is a wide range of relative volumes in which either liquid could be stably continuous. Within this range the phase that becomes continuous is prescribed by the manner of initiating the dispersion. This range was found to be a function principally of the viscosity ratio.Nous étudions les facteurs qui influencent le contrǒle de la phase continue lorsque deux liquides immiscibles sont placés dans un réservoir avec agitation. Nous avons étudié l'effet de la viscosité, de la densité, de la vitesse d'agitation, de la façon d'initier la dispersion, ainsi que des matériaux et de la construction du réservoir avec agitateur.II a été trouve qu'il existe une gamme étendue de volumes relatifs, pour une paire donnée de liquides, dans laquelle un ou l'autre des liquides peut devenir la phase continue stable. A l'intérieur de cette région l'initiation de la dispersion prescrit quel liquide se présente sous la phase continue. La région est une fonction surtout du rapport des viscosités.
Article
Data are reported on phase inversion in concentrated oil-water mixtures dispersed in a fully-baffled stirred tank. The results indicate that water continuous dispersions in which the water concentration is as small as 40% by volume can be formed. For a vertically centered impeller the concentration of the organic liquid required for phase inversion varies inversely with the rate of energy input. The effect of impeller position is also discussed. Cette étude porte sur les proportions et le degré d'agitation requis pour occasionner le passage de l'huile de l'état de phase dispersée à celui de milieu dispersant dans les émulsions d'eau et d'huile. Les résultats indiquent la possibilité de conserver le caractère continu de la phase aqueuse dans un mélange contenant aussi peu que 40% d'eau en volume. Dans le cas d'un agitateur centré verticallement, la proportion d'huile requise pour l'inversion de phase est inversement proportionnelle à la puissance fournie. L'influence de la position de l'agitateur est aussi étudiée.
Article
A study has been made of phase inversions which can occur in agitated liquid—liquid dispersions of hydrocarbons (“oil”) and water when non-ionic surfactants are present. Various modes of phase behaviour have been established and the role of the surfactant phase is clarified. Transitional inversion was induced at room temperature by changing the surfactant composition; this altered the hydrophile—lipophile balance (HLB) of the surfactant. This inversion occurred over a very narrow range of HLB when three phases existed. Transitions could also be induced by changing the water—oil ratio (WOR). In these cases, transitions were not reversible; the value of WOR for transition when oil was added to water was not the same as the value observed when water was added to oil. These transitions could not always be described as true inversions and the formation of complex drops (double emulsions) was possible. The location of boundaries for phase inversion, which resulted from changing the WOR, depended on the intensity of agitation and on the ratio of liquid addition to the dispersion. With any particular system of oil, water and surfactant, phase behaviour and inversion boundaries can be represented on a single map. The form of the map was influenced by the type of non-ionic surfactant that was used.
Article
It has been found that W/O/W-type multiple-phase emulsions can be prepared by a two-step procedure of emulsification using a variety of nonionic emulsifying agents. The first step in emulsification, providing the emulsion, was made with an organophilic emulsifying agent such as Span 80, and the second step, providing the W/O/W emulsion, was then carried out by mixing the emulsion with an aqueous solution of a polyoxyethylene-type hydrophilic emulsifying agent. Yield of the W/O/W emulsion was measured by the amount of marker (glucose), which migrated from the dispersed globules to the continuous phase, using dialysis for separating the migrated glucose from the newly prepared W/O/W emulsion, and using Nelson-Somogyi's technique for analyzing the amount of the glucose. The results of the yield measurement for a series of the samples indicate that the significant factor affecting the W/O/W emulsion formation is the ratio of the organophilic emulsifying agent in the oil phase to the hydrophilic emulsifying agent in the aqueous continuous phase. The correlation between the yield of the W/O/W emulsion and the ratio of emulsifying agents used for the two-step in emulsification shows that when one desires a yield of the W/O/W emulsion higher than 90%, the organophilic emulsifying agent needed is 10 times or more the amount of the hydrophilic emulsifying agent.
Article
In the present article we analyse the influence of various factors, both thermodynamic and hydrodynamic, on the stability of emulsion systems. The effect of the droplet size on the droplet lifetime in an emulsion cream is quantified. The comparative importance of kinetic factors such as surface and bulk diffusion fluxes, or viscous and elastic surface stresses, is investigated. The fact that the emulsion films drain much more slowly when the surfactant is dissolved in the continuous phase (rather than in the disperse phase) provides a new understanding of the Bancroft rule and the process of chemical demulsification. New thermodynamic aspects of emulsion stability are also discussed. One of them is the relatively high surface electric potential of pure oil-water interfaces and adsorption monolayers of non-ionic surfactants. Another aspect is the role of non-DLVO surface forces, such as the hydration repulsion, oscillatory structural and depletion forces due to the presence of surfactant micelles. A criterion of emulsion stability is formulated synthesizing the effects of the major factors. Finally we consider the importance of the kinetic phenomena in emulsions formed from non-pre-equilibrated phases.
Article
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