Micro-Surface and -Interfacial Tensions Measured Using the Micropipette Technique: Applications in Ultrasound-Microbubbles, Oil-Recovery, Lung-Surfactants, Nanoprecipitation, and Microfluidics

This review presents a series of measurements of the surface and interfacial tensions we have been able to make using the micropipette technique. These include: equilibrium tensions at the air-water surface and oil-water interface, as well as equilibrium and dynamic adsorption of water-soluble surfactants and water-insoluble and lipids. At its essence, the micropipette technique is one of capillary-action, glass-wetting, and applied pressure. A micropipette, as a parallel or tapered shaft, is mounted horizontally in a microchamber and viewed in an inverted microscope. When filled with air or oil, and inserted into an aqueous-filled chamber, the position of the surface or interface meniscus is controlled by applied micropipette pressure. The position and hence radius of curvature of the meniscus can be moved in a controlled fashion from dimensions associated with the capillary tip (~5–10 μm), to back down the micropipette that can taper out to 450 μm. All measurements are therefore actually made at the microscale. Following the Young–Laplace equation and geometry of the capillary, the surface or interfacial tension value is simply obtained from the radius of the meniscus in the tapered pipette and the applied pressure to keep it there. Motivated by Franklin’s early experiments that demonstrated molecularity and monolayer formation, we also give a brief potted-historical perspective that includes fundamental surfactancy driven by margarine, the first use of a micropipette to circuitously measure bilayer membrane tensions and free energies of formation, and its basis for revolutionising the study and applications of membrane ion-channels in Droplet Interface Bilayers. Finally, we give five examples of where our measurements have had an impact on applications in micro-surfaces and microfluidics, including gas microbubbles for ultrasound contrast; interfacial tensions for micro-oil droplets in oil recovery; surface tensions and tensions-in-the surface for natural and synthetic lung surfactants; interfacial tension in nanoprecipitation; and micro-surface tensions in microfluidics.

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Surface and interfacial tensions of aqueous dispersions of charged colloidal (clay) particles

Canadian Journal of Chemistry ◽

10.1139/v94-243 ◽

1994 ◽

Vol 72 (9) ◽

pp. 1915-1920 ◽

Cited By ~ 23

Author(s):

Laurier L. Schramm ◽

Loren G. Hepler

Keyword(s):

Interfacial Tension ◽

Pure Water ◽

Surface Tensions ◽

Flow Rates ◽

Aqueous Dispersions ◽

Clay Particles ◽

Interfacial Tensions ◽

Aqueous Suspensions ◽

Colloidal Clay ◽

Effect Of Surface

We have measured (du Nouy ring and maximum bubble pressure methods) suspension–air surface tensions of aqueous suspensions of montmorillonite and have observed that these surface tensions are larger than those of pure water at the same temperatures. Further measurements have shown that dispersed montmorillonite also increases the suspension–toluene interfacial tension compared with that of pure water–toluene. Similar measurements on aqueous suspensions of kaolinite have yielded suspension–air interfacial tensions with uncertainties as large as the observed (small) effect, and also shown that the suspension–toluene interfacial tension is decreased (opposite to the effect of montmorillonite) by amounts larger than the experimental uncertainties. Measurements of maximum bubble pressures at different flow rates have provided information about the effect of surface age on observed surface tensions.

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Optimization of Surfactant and Polymer for SP Flooding of Zahra Oil

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.535.701 ◽

2014 ◽

Vol 535 ◽

pp. 701-704 ◽

Cited By ~ 1

Author(s):

Peng Lv ◽

Ming Yuan Li ◽

Mei Qin Lin

Keyword(s):

Interfacial Tension ◽

Polymer Solution ◽

Enhanced Oil Recovery ◽

Oil Recovery ◽

High Viscosity ◽

Oil Field ◽

Interfacial Tensions

Producing ultra-low interfacial tensions and maintaining high viscosity is the most important mechanism relating to SP flooding for enhanced oil recovery. The interfacial tension between surfactant (PJZ-2 and BE)/polymer solution and Zahra oil was evaluated in the work. Based on the evaluatiojn of interfacial tension, the polymer FP6040s/surfactant BE system was selected as the SP flooding system for Zahra oil field.

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Evaluation of the Interfacial Tension Between a Microemulsion and the Excess Dispersed Phase

Society of Petroleum Engineers Journal ◽

10.2118/9281-pa ◽

1981 ◽

Vol 21 (05) ◽

pp. 593-602 ◽

Cited By ~ 12

Author(s):

E. Ruckenstein

Keyword(s):

Interfacial Tension ◽

Oil Recovery ◽

Phase Inversion ◽

The Other ◽

Dispersed Phase ◽

Middle Phase ◽

Inversion Point ◽

Interfacial Tensions ◽

Dispersed Medium ◽

Oil Water

Abstract From a consideration of the thermodynamic stability of microemulsions, one can establish a relation between the interfacial tension y at the surface of the globules and the derivative, with respect to their radius re, of the entropy of dispersion of the globules in the continuous medium. Expressions for the entropy of dispersion are used to show that gamma is approximately proportional to kT/r2e, where k is Boltzmann's constant and T is the absolute temperature. Since the environment of the interface between the microemulsion and the excess dispersed medium is expected to be similar to that at the surface of the globules, these expressions are used to evaluate the interfacial tension between microemulsion and excess dispersed medium. Values between 10 and 10 dyne/cm that decrease with increasing radii are obtained, in agreement with the range found experimentally by various authors. The origin of the very small interfacial tensions rests ultimately in the adsorption of surfactant and cosurfactant on the interface between phases. The effect on the interfacial tension of fluctuations from one type of microemulsion to the other, which may occur near the phase inversion point, is discussed. Introduction The system composed of oil, water, surfactant, cosurfactant, and salt exhibits interesting phase equilibria. For sufficiently large concentrations of surfactant, a single phase can be formed either as a microemulsion or as a liquid crystal. In contrast, at moderate surfactant concentrations, two or three phases can coexist. For moderate amounts of salt (NaCl), an oil phase is in equilibrium with a water-continuous microemulsion, whereas for high salinity, an oil-continuous microemulsion coexists with a water phase. At intermediate salinity, a middle phase (probably a microemulsion) composed of oil, water, surfactants, and salt forms between excess water and oil phases. Extremely low interfacial tensions are found between the different phases, with the lowest occurring in the three-phase region. These systems have attracted attention because of their possible application to tertiary oil recovery. It has been shown that the displacement of oil is most effective at very low interfacial tensions.Microemulsions have been investigated with various experimental techniques, such as low-angle X-ray diffraction, light scattering, ultracentrifugation, electron microscopy, and viscosity measurements. These have shown that the dispersed phase consists of spherical droplets almost uniform in size. While it is reasonable to assume that the microemulsions coexisting with excess oil or water contain spherical globules of the dispersed medium, the structure of the middle-phase microemulsion is more complex. Experimental evidence obtained by means of ultracentrifugation indicates, however, that at the lower end of salinity the middle phase contains globules of oil in water, while at the higher end the middle phase is oil continuous. A phase inversion must occur, at an intermediate salinity, from a water-continuous to an oil-continuous microemulsion. The free energies of the two kinds of microemulsions are equal at the inversion point. Since their free energy of formation from the individual components is very small, small fluctuations, either of thermal origin or due to external perturbations, may produce changes from one type to the other in the vicinity of the inversion point. As a consequence, near this point, it is possible that the middle phase is composed of a constantly changing mosaic of regions of both kinds of microemulsions. SPEJ P. 593^

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Interfacial Tension Along the Binodal Curve in the Benzene-Ethanol-Water and n-Hexane-Acetone-Water Ternary Systems at 25 °C

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19960489 ◽

1996 ◽

Vol 61 (4) ◽

pp. 489-500 ◽

Cited By ~ 4

Author(s):

Markéta Čechová ◽

Lidmila Bartovská

Keyword(s):

Interfacial Tension ◽

Ternary Systems ◽

Binodal Curve ◽

Miscibility Gap ◽

Surface Tensions ◽

Interfacial Tensions ◽

Acetone Water

The surface tensions, interfacial tensions and densities of conjugate solutions of compositions lying in the miscibility gap were measured for two ternary systems, viz. benzene-ethanol-water and n-hexane-acetone-water, at 25 °C.

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Multiphase Microemulsion Systems

Society of Petroleum Engineers Journal ◽

10.2118/5565-pa ◽

1976 ◽

Vol 16 (03) ◽

pp. 147-160 ◽

Cited By ~ 217

Author(s):

R.N. Healy ◽

R.L. Reed ◽

D.G. Stenmark

Keyword(s):

Interfacial Tension ◽

Physicochemical Properties ◽

Phase Behavior ◽

Oil Recovery ◽

Displacement Efficiency ◽

Oil Composition ◽

Alkyl Aryl ◽

Optimal Salinity ◽

Interfacial Tensions ◽

Multiphase Behavior

Abstract Economical microemulsion flooding inevitably involves microemulsion phases immiscible with oil or water, or both; oil recovery is largely affected by displacement efficiency during the immiscible regime. Therefore, it is essential to understand the role of interfacial tension in relation to multiphase microemulsion behavior. Three basic types of multiphase systems are identified and used to label phase transitions that occur when changes are made in salinity, temperature, oil composition, surfactant structure, cosolvent, and dissolved solids in the aqueous phase. Directional effects of these changes on phase behavior, interfacial tension, and solubilization parameter are tabulated for the alkyl aryl sufonates studied. A relationship between interfacial tension and phase behavior is established. This provides the phase behavior is established. This provides the basis for a convenient method for preliminary screening of surfactants for oil recovery. Interfacial tensions were found to correlate with the solubilization parameter for the various microemulsion phases, a result that can substantially reduce the number of interfacial tensions that must be determined experimentally for a given application. Introduction A previous paper established that microemulsion flooding is a locally miscible process until slug breakdown and is an immiscible, rate-dependent displacement thereafter; furthermore, for an effective flood, most of the oil recovered is acquired during the immiscible regime. An extensive study of single-phase regions defined classes of micellar structures for a particular surfactant; however, it was subsequently shown these did not affect oil recovery, provided viscous, lamellar structures were avoided. Optimal salinity was introduced as defining a ternary diagram having the least extensive multiphase region, a desirable feature in that locally miscible displacement is prolonged. Immiscible displacement after slug breakdown is known to depend on interfacial tension through its inclusion in the capillary number. A brief study showed chat interfacial tension varied widely throughout the multiphase region; accordingly, it is anticipated that oil recovery will depend on details of multiphase behavior in relation to interfacial tension, as well as on injection composition. Consider a flood sufficiently advanced that the microemulsion slug has broken down. A microemulsion phase remains that is immiscible with water or oil, phase remains that is immiscible with water or oil, or both, and displacement has assumed an immiscible character. The problem is twofold: to design a microemulsion slug that effectively displaces oil at the front and that is effectively displaced by water at the back. Both aspects are essential and, therefore, both microemulsion-oil and microemulsion-water interfacial tensions must be very low. The condition where these two tensions are low and equal will be of particular significance. The purpose of this paper is to explore physicochemical properties of multiphase physicochemical properties of multiphase microemulsion systems with a view toward understanding immiscible aspects of microemulsion flooding, and with the expectation of developing systematic screening procedures useful for design of optimal floods. Equilibration is an essential part of this study. Even the simplest of these systems is so complex it may well happen that nonequilibrium effects will never be understood sufficiently to be usefully accommodated in mathematical simulation of microemulsion flooding. In any event, equilibration, although time consuming, leads to a coherent picture of multiphase behavior that can be correlated with flooding results. Multiphase behavior of "simple" ternary systems divides into three basic classes. Dependence of phase behavior on salinity, with respect to these phase behavior on salinity, with respect to these classes, leads to correlations of interfacial tension with the solubilization parameter. These correlations are studied in relation to surfactant structure, temperature, cosolvents, oil composition, and brine composition. Optimal salinity again plays an important role, especially in relation to interfacial tension. SPEJ P. 147

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Vesicular Dispersion Delivery Systems and Surfactant Waterflooding

Society of Petroleum Engineers Journal ◽

10.2118/9349-pa ◽

1982 ◽

Vol 22 (01) ◽

pp. 37-52 ◽

Cited By ~ 17

Author(s):

Jorge E. Puig ◽

Elias I. Franses ◽

Yeshayahu Talmon ◽

H. Ted Davis ◽

Wilmer G. Miller ◽

...

Keyword(s):

Interfacial Tension ◽

Oil Recovery ◽

Liquid Crystalline ◽

Capillary Forces ◽

Residual Oil ◽

Interfacial Tensions ◽

Low Concentration ◽

Tertiary Oil Recovery ◽

Oil Water ◽

Recovery Methods

Abstract Surfactant waterflooding processes that rely on ultralow interfacial tensions suffer from surfactant retention by reservoir rock and from the need to avoid injectivity problems. New findings reported here open the possibility that by delivering the surfactant in vesicle form, more successful low-concentration, alcohol-free surfactant waterflooding processes can be designed. Basic studies of low concentration (less than 2 wt %) aqueous dispersions of lamellar liquid crystals of a model surfactant, Texas No. 1, have established the role of dispersed liquid crystallites in the achievement of ultralow tensions between oil and water. Recent work, including fast-freeze, cold-stage transmission electron microscopy (TEM), reveals that sonication both in the absence and the presence of sodium chloride converts particulate dispersions of Texas No. 1 into dispersions of vesicles, which are spheroidal bilayers or multilayers, less than 0.1 mum in diameter filled with aqueous phase. Vesicles ordinarily revert only very slowly to the bulk liquid crystalline state. We find, however, that their stability depends on their preparation and salinity history, and that contact with oil can accelerate greatly the reversion of a vesiculated dispersion and enable it to produce low tensions between oil and water. Tests with Berea cores show that surfactant retention and attendant pressure buildup can be reduced greatly by sonicating Texas No. 1 dispersions to convert liquid crystallites to vesicles. In simple core-flooding experiments both the unsonicated liquid crystalline dispersions and the sonicated vesicle dispersions are able to produce substantial amounts of residual oil. We point out implications and directions for further investigation. Introduction Methods of enhancing, petroleum recovery, especially tertiary recovery, following the primary and secondary stages, are under intense research and development. Among these are at least two classes of surfactant-based recovery methods-surfactant waterflooding and so-called micellar or microemulsion flooding. Gilliland and Conley suggest that of the various enhanced-recovery methods, surfactant waterflooding has the potential for the widest application in the U.S. Residual oil is trapped as blobs in porous rock by capillary forces. The number of mechanisms is limited both for reducing entrapment and for mobilizing that residual oil remaining entrapped, there by improving the microscopic displacement efficiency of a petroleum recovery process. Taber and Melrose and Brandner established that tertiary oil recovery by an immiscible flooding process is possible by increasing the capillary number, which measures the ratio of Darcy flow forces of mobilization to capillary forces of entrapment. In practice this can be achieved by lowering the oil-water interfacial tension to about 10 mN/m or less. That this is feasible in the surfactant waterflooding range-i.e. at surfactant concentration less than those characterizing the microemulsion flooding range-and in the absence of cosurfactants or cosolvents that typify microemulsions is well established. Gale and Sandvik suggested four criteria for selecting a surfactant for a tertiary oil-recovery process:low oil-water interfacial tension,low adsorption.compatibility with reservoir fluids, andlow cost. For a given oil and type of surfactant, it has been shown that the interfacial tensions are extremely sensitive to surfactant molecular weight. SPEJ P. 37^

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Effects of Surfactant and Hydrophobic Nanoparticles on the Crude Oil-Water Interfacial Tension

Energies ◽

10.3390/en14196234 ◽

2021 ◽

Vol 14 (19) ◽

pp. 6234

Author(s):

Xu Jiang ◽

Ming Liu ◽

Xingxun Li ◽

Li Wang ◽

Shuang Liang ◽

...

Keyword(s):

Interfacial Tension ◽

Crude Oil ◽

Oil Recovery ◽

Nanoparticle Concentration ◽

Interfacial Phenomenon ◽

Interfacial Tensions ◽

Oil Water ◽

Span 80 ◽

The Impact ◽

Interfacial Characteristics

Surfactants and nanoparticles play crucial roles in controlling the oil-water interfacial phenomenon. The natural oil-wet mineral nanoparticles that exist in crude oil could remarkably affect water-oil interfacial characteristics. Most of recent studies focus on the effect of hydrophilic nanoparticles dispersed in water on the oil-water interfacial phenomenon for the nanoparticle enhanced oil recovery. However, studies of the impact of the oil-wet nanoparticles existed in crude oil on interfacial behaviour are rare. In this study, the impacts of Span 80 surfactant and hydrophobic SiO2 nanoparticles on the crude oil-water interfacial characteristics were studied by measuring the dynamic and equilibrium crude oil-water interfacial tensions. The results show the existence of nanoparticles leading to higher crude oil-water interfacial tensions than those without nanoparticles at low surfactant concentrations below 2000 ppm. At a Span 80 surfactant concentration of 1000 ppm, the increase of interfacial tension caused by nanoparticles is largest, which is around 8.6 mN/m. For high Span 80 surfactant concentrations, the less significant impact of nanoparticles on the crude oil-water interfacial tension is obtained. The effect of nanoparticle concentration on the crude oil-water interfacial tension was also investigated in the existence of surfactant. The data indicates the less significant influence of nanoparticles on the crude oil-water interfacial tension at high nanoparticle concentration in the presence of Span 80 surfactant. This study confirms the influences of nanoparticle-surfactant interaction and competitive surfactant molecule adsorption on the nanoparticles surfaces and the crude oil-water interface.

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Immiscible Microemulsion Flooding

Society of Petroleum Engineers Journal ◽

10.2118/5817-pa ◽

1977 ◽

Vol 17 (02) ◽

pp. 129-139 ◽

Cited By ~ 84

Author(s):

Robert N. Healy ◽

Ronald L. Reed

Keyword(s):

Interfacial Tension ◽

Oil Recovery ◽

Surfactant Concentration ◽

Miscible Displacement ◽

Immiscible Displacement ◽

Microemulsion System ◽

Core Flooding ◽

Middle Phase ◽

Interfacial Tensions ◽

Excess Water

Abstract Economical microemulsion flooding inevitably involves microemulsion phases that are immiscible with water, oil, or both. Oil recovery is largely affected by displacement efficiency in the immiscible regime. Therefore, it is pertinent to study this immiscible aspect in relation to variables that affect phase behavior and interfacial tension between phases. This is accomplished through core flooding experiments wherein microemulsions immiscible with oil and/or water are injected to achieve enhanced oil recovery. One advantage of such an immiscible microemulsion flood is that surfactant concentration can be small and slug size large, thereby reducing deleterious effects of reservoir heterogeneity; a disadvantage is that the temporary high oil recovery accompanying locally miscible displacement before slug breakdown is reduced. Final oil saturation remaining after lower, middle, and upper-phase microemulsion floods is studied as a function of salinity, cosolvent, temperature, and surfactant structure; and results are related to interfacial tension, phase behavior and solubilization parameters. A conclusion is that immiscible microemulsion flooding is an attractive alternative to conventional microemulsion processes. Oil recovery obtained from microemulsion slugs is correlated with capillary number based on what is called the controlling interracial tension. Physically, this means the least effective of the Physically, this means the least effective of the displacement processes at the slug front or rear determines the flood outcome. Finally, a screening procedure is developed that is useful for either immiscible or conventional microemulsion floods and that can reduce the number of core floods required to estimate oil recovery potential for a candidate microemulsion system. potential for a candidate microemulsion system Introduction This is the fourth in a sequence of papers dealing with miscible and immiscible aspects of microemulsion flooding. The first of these papers identified micellar structures above the binodal curve and showed how the region of miscibility could be maximized at the expense of the multiphase region, thereby prolonging locally miscible displacement. This was accomplished by varying salinity, and the notion of optimal salinity was introduced as that which minimized the extent of the multiphase region. Interfacial tensions within the multiphase region were measured and found to vary nearly three orders of magnitude, depending on WOR and surfactant concentration. Careful isothermal pre-equilibration of bulk phases was a requisite to all interfacial tension measurements. The second paper emphasized core flooding behavior and distinguished locally miscible displacement before slug breakdown, from immiscible displacement occurring thereafter. Fractional oil flow was correlated with capillary number and it was found that an effective immiscible displacement cannot be distinguished from the locally miscible case. Further, during an effective flood, the greater part of the oil was recovered during the immiscible regime. Finally, it was shown that micellar structure within the miscible region is not of itself an important variable. Having determined that the immiscible aspect of a microemulsion flood was important and dominant, the third paper dealt extensively with the multiphase region. Microemulsions were classified as lower-phase (1), upper-phase, (u), or middle-phase (m) in equilibrium with excess oil, excess water, or both excess oil and water, respectively. Transitions among these phases were studied and systematized as functions of a number of variables. Solubilization parameters for oil and water in microemulsions were introduced and shown to correlate interfacial tensions. The middle-phase was identified as particularly significant because microemulsion/excess-oil and microemulsion/ excess-water tensions could be made very low simultaneously. In this paper, the sequence is continued by introducing the notion of an immiscible microemulsion flood as one having an injection composition in the neighborhood of the multiphase boundary. SPEJ P. 129

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Smart Polymers and their Applications: A Review

International Journal of Current Pharmaceutical Review and Research ◽

10.25258/ijcprr.v8i03.9220 ◽

2017 ◽

Vol 8 (03) ◽

Author(s):

Gore S. A. ◽

Gholve S. B. ◽

Savalsure S. M. ◽

Ghodake K. B. ◽

Bhusnure O. G. ◽

...

Keyword(s):

Oil Recovery ◽

Water Soluble ◽

Solution Temperature ◽

Smart Polymers ◽

Stimuli Responsive ◽

Responsive Materials ◽

Water Soluble Polymers ◽

Commercial Applications ◽

Stimuli Sensitive ◽

External Stimuli

Smart polymers are materials that respond to small external stimuli. These are also referred as stimuli responsive materials or intelligent materials. Smart polymers that can exhibit stimuli-sensitive properties are becoming important in many commercial applications. These polymers can change shape, strength and pore size based on external factors such as temperature, pH and stress. The stimuli include salt, UV irradiation, temperature, pH, magnetic or electric field, ionic factors etc. Smart polymers are very promising applicants in drug delivery, tissue engineering, cell culture, gene carriers, textile engineering, oil recovery, radioactive wastage and protein purification. The study is focused on the entire features of smart polymers and their most recent and relevant applications. Water soluble polymers with tunable lower critical solution temperature (LCST) are of increasing interest for biological applications such as cell patterning, smart drug release, DNA sequencing etc.

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