Oil/water systems

Fig. 1. Phase diagram of an amphiphile—oil—water system that forms a middle-phase microemulsion, definition of microemulsion, and illustration of the...

Evidence exists that the relative solubility of amines and inhibitors in heterogeneous oil-water systems could be decisive in formation of nitrosamines and blocking these reactions, Nitrosopyrrolidine formation in bacon predominates in the adipose tissue despite the fact that its precursor, proline, predominates in the lean tissue (5,6,7). Mottram and Patterson (8) partly attribute this phenomenon to the fact that the adipose tissue furnishes a medium in which nitrosation is favored, Massey, et al, (9) found that the presence of decane in a model heterogeneous system caused a 20-fold increase in rate of nitrosamine formation from lipophilic dihexylamine, but had no effect on nitrosation of hydrophilic pyrrolidine. Ascorbic acid in the presence of decane enhanced the synthesis of nitrosamines from lipophilic amines, but had no effect on nitrosation of pyrrolidine. The oil-soluble inhibitor ascorbyl palmitate had little influence on the formation of nitrosamines in the presence or absence of decane. 

Interfacial rheologic properties of different crude oil-water systems were determined in wide temperature and shear rate ranges and in the presence of inorganic electrolytes, surfactants, alkaline materials, and polymers [1056]. 

Caustic Waterflooding. In caustic waterflooding, the interfacial rheologic properties of a model crude oil-water system were studied in the presence of sodium hydroxide. The interfacial viscosity, the non-Newtonian flow behavior, and the activation energy of viscous flow were determined as a function of shear rate, alkali concentration, and aging time. The interfacial viscosity drastically... 

D. Avlonitis, A. Danesh, A. C. Todd, and T. Baxter. The formation of hydrates in oil-water systems. In Proceedings Volume, pages 15-34. 4th Bhran Multi-Phase Flow Int Conf (Nice, France, 6/19-6/21), 1989. 

I. Lakatos and J. Lakatos-Szabo. Effect of lOR/EOR (improved oil recovery/enhanced oil recovery) chemicals on interfacial rheological properties of crude oil/water systems. In Proceedings Volume. SPE Oilfield Chem Int Symp (Houston, TX, 2/13-2/16), 2001 SPE Number 65391. 

J. Lakatos-Szabd and I. Lakatos. Effect of sodium hydroxide on interfacial rheological properties of oil-water systems. In Colloids Surfaces, Sect A, volume 149, pages 507-513. 9th Surface Colloid Sci Int Conf (Sofia, Bulgaria, 7/6-7/12), 1997. 

J. Lakatos-Szabo, I. Lakatos, and B. Kosztin. Role of interfacial rheological properties of oil/water systems in mechanism and design of EOR/IOR technologies. In Proceedings Volume, number 057. 9th EAGE Impr Oil Recovery Europe Symp (The Hague, Netherlands, 10/20-10/22) Proc, 1997. 

Whereas the relationship of solute permeability with lipophilicity has been studied in a large number of in vivo systems (including intestinal absorption models [54,55], blood-brain [56 58] and blood nerve [59] barrier models, and cell culture models [60 62], to name just a few), numerous in vitro model systems have been developed to overcome the complexity of working with biological membranes [63-66]. Apart from oil-water systems that are discussed here, the distribution of a solute between a water phase and liposomes is... 

Karpfen, F. M., and J. E. B. Randles, Ionic equilibria and phase-boundary potentials in oil-water systems, Trans. Faraday Soc.f 49, 823 (1953). 

The flow patterns in liquid-liquid systems have not been as extensively studied as those in gas-liquid systems. However, Russell et al. (R6), and Charles et al. (C3) have studied the flow of oils and water in horizontal pipes and have presented flow-pattern charts for the various oil-water systems. It is very difficult to predict the flow pattern for a liquid-liquid system, unless the liquids have physical properties similar to those of water and the oils used by Govier and co-workers. The Baker chart might be used to give a first estimate of the flow pattern for a liquid-liquid system, but the viscosity of the less-dense phase is not included in the coordinate parameters, and the feasibility of such an approach has never been investigated. 

The demulsification data with four different demulsifiers for a crude oil-water system (Table I) support this conclusion. Structurally, the demulsifier PI and R0 are of moderate (MW 2,000-5,000) molecular weights, whereas PI and P2 are large (MW >50,000) three dimensional structures. 

Table I. Comparison of Effectiveness and Interfacial Properties of Different Demulsifiers in a Crude Oil-Water System...

Due to the water requirement of biocatalytic systems, BDS is typically carried out as a two-phase aqueous-oil process. However, increased sulfur removal rates could be accomplished by using an aqueous-alkane solvent catalytic system [46,203,220,255], The BDS catalytic activity depends on both, the biocatalysts and the nature of the feedstock. It can vary from low activity for crude oil to as high as 60% removal for light gas-oil type feedstocks [27,203,256], or 70% for middle distillates, 90% for diesel, 70% for hydrotreated diesel, and 90% for cracked feedstocks [203,256], The viscosity of the crude oil poses mixing issues in the two-phase oil-water systems however, such issues are minimal for distillate feedstocks, such as diesel or gasoline [257]. 

Amphiphile-oil-water system, temperature of, 16 424-426 Amphiphiles, 16 420 Amphiphile strength, 6 424 Amphiphilic chemicals, 17 56 Amphiphilic copolymers, 20 482 behavior of, 20 483 well-defined, 20 485-490 Amphiphilic molecules, 15 99-101 Amphiphilic plasticizers, 14 480 Amphiphilic polymer blend, 23 720 Amphiphilic polymers statistical, 20 484-490 stimuli-responsive, 20 482-483 Ampholytes, 9 746-747 Amphoteric cyclocopolymers, water-soluble, 23 721 Amphoteric starches, 4 722 Amphoteric (zwitterionic) surfactants, 24 148... 

The work of adhesion is influenced by the orientation of the molecules at the interface. For example, with the help of Table A.4.1 and Eq. (A.4.8), the work of adhesion of n-decane-water (corresponding to a paraffinic oil-water system) and of glycerol-water can be computed to be 40 10 3 J nr2 and 56x 10 3 J nr2, respectively. It requires more work to separate the polar glycerol molecules (oriented with the OH groups toward the water) from the water phase than the nonpolar hydrocarbon molecules. For paraffinic oils Woo is about 44 mj nr2, for water Www is 144 mj nr2, and for glycerol Woo is 127 mJ nr2. 

Thus, an estimation can be made of the hydrophilicity of the crown ring. The acetal-type crown ring obtained from hexaethyl-ene glycol and a higher aliphatic aldehyde is estimated to be e-quivalent to about four OE units in an alkyl POE monoether, from our study of the cloud point (11). Moroi et al. concluded, from a comparison of the cmc, that a diaza-18-crown-6 is equivalent to 20 OE units in the usual type of nonionic (12). Okahara s group evaluated the effective HLB based on the cloud point, phenol index and phase-inversion-temperature in emulsion of oil/water system and they concluded that 18-crown-6 and monoaza-18-crown-6 rings with dodecyl group are approximately equivalent to 4.0 and 4.5 units, respectively, of OE chains with the same alkyl chain (17). 

Bennett and Larter (1997) also studied the solvation of alkylphenols in crude oil-water systems at equilibrium to obtain partitioning coefficients under variable temperature, pressure, and water salinity concentration. Alkylphenol depletion from crude oil, expressed by phenol, cresols, and 3,5 dimethyl phenol, versus temperature in a range of 25-125°C, is given in terms of partition coefficient (P) values (Fig. 16.22). Partition coefficient values increase with addition of alkyl groups to the phenol nucleus. Note that the alkylphenol partition coefficient curves for different isomers tend to converge at higher temperatures and, as a consequence, differences between phenol and p-cresol decrease with increases in temperature. Similar results for oil-deionised water and oil-brine experiments show that increasing temperature leads to a decrease in partition coefficient values. 

B.W. Brooks and H.N. Richmond Phase Inversion in Non-Ionic Surfactant-Oil-Water Systems, I. The Effect of Transitional Inversion on Emulsion Drop Size. Chem. Eng. Sci. 49, 1053 (1994). 

M. Perez, N. Zambrano, M. Ramirez, E. Tyrode, and J.L. Salager Surfactant-Oil-Water System near the Affinity Inversion. XII. Emulsion Drop Size Formulation and Composition. J. Dispersion Sci. Technol. 23, 55 (2002). 

J.L. Salager, M. Minana-Perez, M. Perez-Sanchez, M. Ramirez-Gouveia, and C.I. Rojas Surfactant-Oil-Water Systems near the Affinity Inversion. Part HI The Two Kinds of Emulsion Inversion. J. Dispersion Sci. Technol. 4, 313 (1983). 

In fact, the state obtained by mixing oil and water is an important example of interfacial behavior of lic]iLid lic iiid2. Emulsions of oil-water systems are useful in many aspects of daily life, such as milk, foods, paint, oil recovery, pharmaceutical, and cosmetics. The colloidal chemistry of milk makes it the most complicated naturally made product. 

When a surface-active substance is added to an oil-water system, the magnitude of IFT decreases from 50 mN/m to 30 (or lower [less than 1] mN/m. This leads to the observation that, on shaking, the decreased IFT of the oil-water system leads to smaller drops of the dispersed phase (oil or water). The smaller drops also lead to a more stable emulsion. Depending on the surfactant used, either an oil in water (O/W) or a water in oil (W/O) emulsion will be obtained. These experiments where oil and water, or oil and water + surfactant are shaken together, are shown in Figure 9.1. 

The property of interest to characterize a surfactant or a mixture of surfactants is its hydrophilic-lipophilic tendency, which has been expressed in many different ways through a variety of concepts such as the hydrophiUc-lipophilic balance (HLB), the phase inversion temperature (PIT), the cohesive energy ratio (CER), the surfactant affinity difference (SAD) or the hydrophilic-lipophilic deviation (HLD) [1], which were found to be more or less satisfactory depending on the case. In the next section, the quantification of the effects of the different compounds involved in the formulation of surfactant-oil-water systems will be discussed in details to extract the concept of characteristic parameter of the surfactant, as a way to quantify its hydrophilic-lipophilic property independently of the nature of the physicochemical environment. 

Fig.1 Phase behavior types of surfactant-oil-water systems as Winsor Diagrams for difer-ent cases of the ratio R of interactions between the surfactant adsorbed at interface and the oil and water molecules...

The phase behavior of anionic-cationic surfactant mixture/alcohol/oil/ water systems exhibit a similar effect. First of all, it should be mentioned that because of the low solubility of the catanionic compound, it tends to precipitate in absence of co-surfactant, such as a short alcohol. When a small amount of cationic surfactant is added to a SOW system containing an anionic surfactant and alcohol (A), three-phase behavior is exhibited at the proper formulation, and the effect of the added cationic surfactant may be deduced from the variation of the optimum salinity (S ) for three-phase behavior as in Figs. 5-6 plots. Figure 16 (left) shows that when some cationic surfactant is added to a SOWA system containing mostly an anionic surfactant, the value of In S decreases strongly, which is an indication of a reduction in hydrophilicity of the surfactant mixture. The same happens when a small amount of anionic surfactant is added to a SOWA system containing mostly a cationic surfactant. As seen in Fig. 16 (left), the values of In S at which the parent anionic and cationic surfactant systems exhibit three-phase behavior are quite high, which means that both base surfactants, e.g., dodecyl sulfate... 

Salager JL (1996) Quantifying the Concept of Physico-Chemical Formulation in Surfactant-Oil-Water Systems. Prog Colloid Polym Sci 100 137-142... 

Salager JL, Marquez N, Graciaa A, Lachaise J (2000) Partitioning of ethoxylated octylphenol Surfactants in Microemulsion-oil-water Systems. Influence of Temperature and relation between Partitioning Coefficient and Physicochemical Formulation. Langmuir 16 5534-5539... 

Marquez N, Anton RE, Graciaa A, Lachaise J, Salager JL (1995) Partitioning of Ethoxylated Alkyl Phenol Surfactants in Microemulsion-oil-water systems. Colloid Surface A 100 225-231... 

Anton RE, Garces N, Yajure A (1997) A correlation for three-phase behavior of cationic surfactant-oil-water systems. J Dispers Sci Technol 18 539-555... 

Salager JL, Bourrel M, Schechter RS, Wade WH (1979) Mixing rules for optimum phase behavior formulations of surfactant-oil-water systems. Soc Petrol Eng J 19 271-278... 

Salager JL, Minana-Perez M, Perez-Sanchez M, Ramirez-Gouveia M, Rojas Cl (1983) Surfactant-oil-water systems near the affinity inversion. Part III The two kinds of emulsion inversion. J Dispers Sci Technol 4 313... 

Ysambertt F, Anton RE, Salager JL (1997) Retrograde Transition in the phase behavior of surfactant-oil-water systems produced by an oil EACN scan. Colloid Surf A 125 131-136... 

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