Spinning drop technique

J. L. Cayais, R. S. Schecter, and W. H. Wade, The Measurement of Fow Intefacial Tension via the Spinning Drop Technique, Dept, of Chemistry and... 

The spinning drop technique measures the shape of the oil drop in the flooding solution in a capillary tube. An automatic measuring system has been developed by combining a video-image analysis, an automatic recording system, and a computer for calculation of the interfacial tension [1865]. 

T. Yamazaki, K. Aso, H. Okabe, and Y. Akita. Automatic continuous-measuring system of interfacial tension by spinning drop technique. In Proceedings Volume. SPE Asia Pacific Conf (Yokohama, Japan, 4/25 /26), 2000. 

Oil/water interfacial tensions were measured for a number of heavy crude oils at temperatures up to 200°C using the spinning drop technique. The influences of spinning rate, surfactant type and concentration, NaCI and CaCI2 concentrations, and temperature were studied. The heavy oil type and pH (in the presence of surfactant) had little effect on interfacial tensions. Instead, interfacial tensions depended strongly on the surfactant type, temperature, and NaCI and CaCL concentrations. Low interfacial tensions (<0.1 mN/m) were difficult to achieve at elevated temperatures. 

Cayias, J.L. Schechter, R.S. Wade, W.H. The Measurement of Low Interfacial Tension via the Spinning Drop Technique in Adsorption at Interfaces, Mittal, K.L. (Ed.), American Chemical Society Washington, 1975, pp. 234-247. 

Many methods for the measurement of surface and interfacial tensions, details of the experimental techniques, and their limitations are described in several good reviews (27-29). Some methods that are used most in emulsion work are the du Nouy ring, drop weight or volume, pendant drop, and the spinning drop. The spinning drop technique is applicable to the very low interfacial tensions encountered in the enhanced oil recovery and microemulsion fields (30). In all cases, when solutions rather than pure liquids are involved, appreciable changes can take place with time at the surfaces and interfaces. 

Princen ) has extended the spinning drop technique to the case that the rotating cylinder contains a liquid (Lj) emd an air bubble (G) dispersed in another liquid Lj. When drop L2 and bubble G do not touch each other, the surface tension y and the Interfacial tension can be simultaneously determined. However, under certain conditions bubble and drop adhere to each other. Then, as well as the two tensions, the three three-phase contact angles can be simultaneously measured. 

Cayias, J.L. Schecter, R.S. and Wade, W.H., "The Measurement of Low Interfacial Tensions via the Spinning Drop Technique", Departments of Chemistry and Chemical Engineering, University of Texas at Austin, 1975. 

For the system of Figure 9.9 interfacial tension as measured by the spinning drop technique fell during the first few minutes of the experiment to 0.05 mN/m, remained there for about half an hour, then increased over a period of 2 h to 0.2 to 0.3 mN/m, not far below the value of 0.4 mN/m obtained at long times for pure triolein with the same surfactant solution. This behavior indicates that the surfactant film at the interface between the drop and surfactant solution shifted from lipophilic to hydrophilic conditions as oleic acid was solubilized, the minimum in tension occurring at the balanced condition (see Figure 9.3). Support for this interpretation was obtained by repeating... 

Perhaps the most striking property of a microemulsion in equilibrium with an excess phase is the very low interfacial tension between the macroscopic phases. In the case where the microemulsion coexists simultaneously with a water-rich and an oil-rich excess phase, the interfacial tension between the latter two phases becomes ultra-low [70,71 ]. This striking phenomenon is related to the formation and properties of the amphiphilic film within the microemulsion. Within this internal amphiphilic film the surfactant molecules optimise the area occupied until lateral interaction and screening of the direct water-oil contact is minimised [2, 42, 72]. Needless to say that low interfacial tensions play a major role in the use of micro emulsions in technical applications [73] as, e.g. in enhanced oil recovery (see Section 10.2 in Chapter 10) and washing processes (see Section 10.3 in Chapter 10). Suitable methods to measure interfacial tensions as low as 10 3 mN m 1 are the sessile or pendent drop technique [74]. Ultra-low interfacial tensions (as low as 10 r> mN m-1) can be determined with the surface light scattering [75] and the spinning drop technique [76]. 

As the latter is comparatively simple to use it can be regarded as the most suitable method to measure low and ultra-low interfacial tensions. In the following the general features of interfacial tensions in microemulsion systems are presented. The dramatic decrease of the water/oil interfacial tension upon the addition of surfactant, the correlation of interfacial tension and phase behaviour, the variation of the water/oil interfacial tension with the respective tuning parameter and the scaling of the interfacial tension will be discussed in detail. All data presented have been determined using the spinning drop technique [17]. 

With low concentration systems, solubilization effects are small and preequilibration can be avoided. All interfacial tensions measured for this study were obtained using the spinning drop technique (17) and a small oil droplet was simply injected into a tube containing the surfactant formulation without previously contacting these two phases. Obviously, solubilization phenomena still occur in the low concentration systems, but dramatic effects, such as third phase formation or the dissolution of the oil droplet are not observed. 

The interfacial tension for the crude oil-caustic system was measured by the spinning drop technique. The instrument used is similar in design to the one reported by Schechter and Wade (2). 

In many emulsion or microemulsion systems, the interfacial tension between the oil-rich phase and the aqueous solution is very low (or ultralow), which presents considerable difficulties for many experimental methodologies. The most commonly employed approach for measuring ultralow interfaeial tension is the spinning-drop technique (98). However, ADSA has also been used to study these systems and possesses a number of advantages over the... 

C. Axisymmetric Drop Shape Analysis and Spinning Drop Technique... 

The interfacial tension obtained with light scattering method is compared in Table 1, with values obtained by the spinning drop technique on similar samples. They are in good agreement. 

MEASUREMENT OF LOW INTERFACIAL TENSION BETWEEN CRUDE OIL AND FORMATION WATER WITH DISSOLVED SURFACTANTS BY THE SPINNING DROP TECHNIQUE FACT OR FICTION ... 

Experimental set-up and procedure Macroemulsions were produced by constant sonication for a period of about forty-five minutes in a thermostated bath at desired temperatures. Kinematic viscosity and specific conductance data of emulsions were obtained using standard Cannon-Fenske viscometer and conductivity meter, respectively. Bulk density and Screen factors of emulsions and equilibrated phases were determined by standard specific gravity bottles and screen viscometer, respectively. The interfacial tension values of oil/aqueous systems were measured by spinning drop technique. The details of measurement procedures are described elsewhere (4,5). 

The advantage of the spinning-drop technique is that no contact between the fluid interface and a solid surface is required. Because both the drop and the surrounding fluid layer are rather thin, results can be obtained even when the surrounding fluid is somewhat turbid, a frequent occurrence in practice. 

In dealing with microemulsions, for which the spinning-drop technique is primarily used, attention should be paid to first get a sample saturated with the oil phase prior to measuring the interfadal tension, otherwise the injected drop will change its shape at constant rotation speed precluding drop profile measurement, the drop being eventually dissolved in the continuous phase. 

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