Abstract This paper sets out to demonstrate, at lab scale, the feasibility of the two main phases of the process, namely the emulsification of a heavy Venezuelan acidic crude oil (ZUATA), and the subsequent breaking of the oil-in-water emulsion. The heavy ZUATA crude can be emulsified directly by making use of the surfactants naturally present in this rich acid oil. These potential surfactants, mainly represented by naphthenic acids, become effective emulsifiers when salified into naphthenate anions by the addition of bases (soda, ammonia). Stable oil-in-water emulsions, typically with 60 to 65% oil, are obtained by using these two bases. There are a number of advantages to be gained in using ammonia to form the oil-in- water emulsions as opposed to other bases (soda for example) for emulsion breaking and phase separation. The paper demonstrates that it suffices to heat the emulsion to break it. It describes the conditions required for ammonia removal and recovery, and the resulting emulsion breaking. An industrial process for achieving the separation is then proposed.

We point out the specificities of the separation process at work during liquid chromatography of polymers in a gradient of composition of the eluent. The main feature is that, after a transient regime, the concentration profile tends to move as a front, i.e., without diffusive spreading in time. This results in relatively sharp peaks and the uselessness of long columns. We propose a simple analytical model for this self-focusing process that allows us to anticipate optimal conditions of operation. This analysis is supported by experimental tests.

A modern technique for road asphalt paving consists in prior emulsification of asphalt in water and then in spreading the emulsion onto the road. A high self stability of the emulsion is looked for. However, the success of a road work depends heavily on the kinetics of emulsion destabilization upon using. Very complex physico-chemical mechanisms operate during emulsion breaking through the contact with the mineral aggregates, In this paper, we review the three main mechanisms of the breaking of cationic emulsions which are the most widely used for road paving : adsorption onto the mineral surface, pH increase due to the aggregate, water removal. They are independently and quantitatively investigated, anti their operability conditions are analyzed.

We present a simulation of the formation of moderately concentrated oil-in-water emulsions generated by turbulent stirring using an ionic surfactant as emulsifier. The simulation is based on a stochastic model in which the mass transfer between the droplets is induced by breakups and coalescences until statistical equilibrium is established. Breakups and coalescences are controlled by probability functions in which the influence of the emulsifier is introduced through efficiency factors. These factors account for the competition between the main conflicting forces acting on the droplets during turbulent stirring.The model has only two adjustable parameters. With a single pair of values, the droplet distribution can be predicted for a variety of emulsification conditions. In this paper, it is shown that the minimum amount of emulsifier required to produce the finest droplet size distributions of various emulsions can also be successfully predicted.

The longer the chain of the alcohol, the lesser it adsorbs at the interface. As a consequence, long chain alcohols (above C8) enhance the solubilization in optimum surfactant-oil-water systems according to the lipophilic linker effect. The solubilization improvement can be rendered by a multiplicative factor which depends almost linearly upon the chain length of the alcohol (above C8). Alcohol mixing is a way to increase the interaction even more.

The phase behavior and optimum formulation of systems containing commercial polyethoxylated octylphenol surfactant, water, and a mixture of ethyl oleate and hexadecane exhibit variations which may be interpreted by two phenomena: first the partitioning and fractionation of the surfactant species between the different phases, which is found to depend significantly upon the polarity of the oil phase. By taking into account these effects, the interfacial or real formulation can be computed, and a second phenomenon is found, i.e., the segregation of the oil near the interface. The interfacial oil layer segregation has been experimentally put in evidence for the first time through the oil partitioning-fractionation phenomena which occur in low solubilization off-optimum systems containing slightly, swollen micelles. The experimental evidence supports a model in which the oil layer located next to the interface contains more ethyl oleate than the bulk oil phase. At and beyond 50 mol % ethyl oleate in the oil mixture with hexadecane, the interfacial oil behaves as if it were essentially composed of pure ethyl oleate, with an equivalent alkane carbon number (EACN) estimated at 6, a clear hint of its polarity.

In this paper, we study the optimal behavior of water-alcane/(alkyl)benzene blend -polyethyoxylated octylphenol systems as a function of the number of ethylene oxide units of the surfactant. We find this behavior highly nonlinear and we partially interpret it by means of a differential fractionation of the surfactant. Remaining gaps from linearity suggest an interfacial oil segregation that we find favorable to polar and small (alkyl)benzene molecules.

Very lipophilic additives are able to substantially improve the solubilization in surfactant-oil-water microemulsions. The so-called lipophilic linker effect is studied, and its role is discussed.

Thin films of lithium-nickel oxide, whose texture consists of microcrystallites with an average grain size of 50 Å, permit highly reversible electrochemical insertion of lithium ions in Li+ conducting electrolytes. Therefore, the corresponding materials would be of great interest for energy storage applications. In addition, the lithium insertion/extraction reactions in the nickel-based layers are accompanied with a marked color change, making these films of interest for the development of electrochromic displays for the control of light transmission in windows (“smart windows”).

The properties of electrochromic thin film materials, i.e., those that can be reversibly colored by the passage of charge, are described. The application of some of these thin film compounds for the development of electrochromic windows is discussed.

The reaction at room temperature of solid indium trioxide with tin (II) fluoride, chloride and bromide, either solid or in aqueous or alcohol solutions, leads to new indium tin oxihalides. These materials are degenerate semiconductors like indium tin oxide and flourine tin oxide.

The new composition Li0.6+Ni0.70IIO2− was prepared by room temperature electrochemical insertion of lithium into X-ray-amorphous nickel-oxide-based film. The film undergoes a reversible electrochemical Li+ insertion process which is accompanied by a net electrochromic effect.

Fluorinated indium tin oxide (FITO) films have been produced by r.f. magnetron sputtering of a target made of a mixture of indium sesquioxide and tin difluoride. The optical and electrical properties of the films have been investigated and correlated with the composition. The performances of FITO films have been compared with those of ITO films.

It has been shown previously that the phase behavior of water-oil and amphiphile mixtures can be satisfactorily depicted by the R-theory. This theory, originally developed by Winsor, is based on the qualitative consideration of the interactions of the surfactant relatively to oil and water. Firstly, we show experimental evidence of the power of the R-theory as a tool for optimizing microemulsion formulations. Then, we give a thermodynamical justification of the concepts underlying the R-theory. Lastly, it is shown that, with a very limited number of adjustable parameters, it is possible to calculate series of phase diagrams obtained with ethoxylated alkylphenols, n-alkanes and water.

We use a stochastic model to predict the droplet size distribution of emulsions generated in a mixer. The emulsions are made of two immiscible liquids, and do not contain surfactants. The intensity of mixing is measured by the speed of rotation of the propeller stirrer. - The model depends on the two extreme diameters (d min, d max) of the states in which the droplets are classified during the formation of the emulsion. It predicts a lognormal stationary distribution, the two independent parameters of which can be analytically related to d min and d max, by assuming that during the emulsification the breaking/coalescence probabilities of the droplets are time independent and linear functions of the droplet diameter. It can also be related to the speed of rotation of the stirrer by means of the isotropic turbulence theory. — The predicted volume median diameters and standard deviations of the lognormal stationary distributions are in agreement with experiments especially designed to test the model.

Cationic asphalt-in-water emulsions are widely used for road construction and surfacing. These systems are an interesting model for the basic study of emulsions because the high asphalt viscosity allows the system to afford some perturbations without readily producing coalescence. The adsorption of a cationic surfactant, an octadecyl-propylene-diamine, at asphalt-water interface is investigated. The adsorption isotherm was determined using two different experimental procedures. The reversibility of adsorption was studied. A plateau occured on the isotherm at the CMC of surfactant. Its value was used to calculate the molecular packign area of the surfactant. A value of 110 Å2 was found, compared to the 160 Å2 found at the liquid-air interface. This value showed that no more than a monolayer was adsorbed. Due to the adsorbed surfactant cations, the asphalt droplet electrokinetic potential was positive. The zeta potential values and adsorbed amounts were strongly correlated. The zeta maximum value, 105 mV, was reached at the maximum adsorbed amount, 1.5 micromol/m2. An attempt was made to study the time dependence of adsorption.

Description d'une nouvelle methode de purification utilisant un systeme triphasique de microemulsions, dans laquelle les impuretes hydrophobes et hydrophiles peuvent migrer vers la phase superieure laissant un agent de surface purifie dans la phase du milieu

The application of dialysis to establish the chemical composition of the continuous phase of an oil-in-water microemulsion is described. Applied to saturated microemulsions, the method is shown to yield results in full agreement with the titration technique. It is also shown to be applicable to untitratable systems such as unsaturated microemulsions or complex five-component microemulsions which have not been studied by any other method.