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Interfacial tension oleic acid

It is quite clear, first of all, that since emulsions present a large interfacial area, any reduction in interfacial tension must reduce the driving force toward coalescence and should promote stability. We have here, then, a simple thermodynamic basis for the role of emulsifying agents. Harkins [17] mentions, as an example, the case of the system paraffin oil-water. With pure liquids, the inter-facial tension was 41 dyn/cm, and this was reduced to 31 dyn/cm on making the aqueous phase 0.00 IM in oleic acid, under which conditions a reasonably stable emulsion could be formed. On neutralization by 0.001 M sodium hydroxide, the interfacial tension fell to 7.2 dyn/cm, and if also made O.OOIM in sodium chloride, it became less than 0.01 dyn/cm. With olive oil in place of the paraffin oil, the final interfacial tension was 0.002 dyn/cm. These last systems emulsified spontaneously—that is, on combining the oil and water phases, no agitation was needed for emulsification to occur. [Pg.504]

Antonow s rule is tlius only exact when the two mutually saturated liquids possess the same density. The observed values of cti2 should in general be slightly less than those determined from — In the case of oleic acid floating on water Devaux obtained a lens thickness of OT cm. Since p — 0 90 the interfacial surface tension should be O M dyne less than the value obtained with the aid of Antonow s rule. [Pg.98]

In the group with positive spreading coefficients (e.g., toluene-in-water and oleic acid-in-water emulsions), the values ofkj a in both stirred tanks and bubble columns decrease upon the addition of a very small amount of oil, and then increase with increasing oil fraction. In such systems, the oils tend to spread over the gas-liquid interface as thin films, providing additional mass transfer resistance and consequently lower k values. Any increase in value upon the further addition of oils could be explained by an increased specific interfacial area a due to a lowered surface tension and consequent smaller bubble sizes. [Pg.201]

Example 12.6. Between paraffin oil and water, the interfacial tension at 25° C is 7 = 41 mJ/m2. The addition of 1 mM cis-9-octadecanoic acid (oleic acid) reduces the interfacial tension to 31 mJ/m2. As a result the solution becomes acidic. On neutralization by 1 mM NaOH the interfacial tension falls to 7.2 mJ/m2. Further addition of 1 mM NaCl decreases the interfacial tension even to 0.01 mJ/m2 [550],... [Pg.264]

Fig.l Dynamic viscosity of the liquid phase Fig.2 Interfacial tension for the system lino-of the System oleic acid/ethane [1], leic acid/carbon dioxide [2]. Fig.l Dynamic viscosity of the liquid phase Fig.2 Interfacial tension for the system lino-of the System oleic acid/ethane [1], leic acid/carbon dioxide [2].
The effects of pH on microemulsions have been Investigated by Qutubuddin et al. (4,5) who have reported a model pH-dependent microemulsion using oleic acid and 2-pentanol. It has been shown that the effect of salinity on phase behavior can be counterbalanced by pH adjustment under appropriate conditions. Added electrolyte makes the surfactant system hydrophobic while an increase in pH can make it hydrophilic by ionizing more surfactant. Based on the phase behavior of pH-dependent systems, a novel concept of counterbalancing salinity effects with pH is being proposed. The proposed scheme for reducing the sensitivity of ultralow interfacial tension (IFT) to salinity is to add some carboxylate or similar surfactant to a sulfonate system, and adjust the pH. The pK and the concentration of the added surfactant are variables that may be... [Pg.224]

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... [Pg.530]

Macroemulsification For macroemulsification to be important, it is imperative that the interfacial tension between oily soil droplets and bath be low, so that emulsification can be accomplished with very little mechanical work. Here adsorption of surfactants at the oily soil-bath interface, with consequent lowering of the interfacial tensions, may play an important role. Emulsification was found to become a major factor when alkaline builders were added to a cleaning bath containing POE nonionic surfactant and the soil was mineral oil containing 5% oleic acid (Dillan, 1979). It is also involved in the suspension of liquefiable solid soil (Cox, 1987). [Pg.360]

Effect of Surfactant Concentration. Figure 3 compares results of alkane scans for three concentrations of sodium oleate at constant sodium chloride concentration and pH. The 0.002 M solution is derived from 95% oleic acid, the 0.01 M and the 0.1 M solutions are derived from 99% oleic acid. Both the magnitude and the alkane position of minimum interfacial tension (r = 11) are essentially concentration independent under these conditions. Wade, et al (12) reported a similar invariance in nm with a pure alkyl benzene sulfonate, although there was more change in the minimum value of interfacial tension with the sulfonate concentration than is observed with the carboxylate. The interfacial tension at for 0.01 M sodium oleate is in the range of the values of Table I. Very high interfacial tension (> 10 dynes/cm) was found at 0.0001 M sodium oleate in 0.1 M sodium chloride. [Pg.86]

Figure 5 summarizes the results for two concentrations of sodium oleate of varying the pH on interfacial tension. One trend is that the lower the solution pH the lower the interfacial tension. Harkins et al (l6 ) have demonstrated that the interfacial tension between benzene and aqueous sodium oleate is lower when the benzene layer contains oleic acid. Since the partition coefficient of oleic acid between alkane and aqueous sodium oleate greatly favors the alkane phase (17), any oleic acid from hydrolysis would tend to partition into the alkane phase. Thus lowering the solution pH would consequently increase the concentration of oleic acid in the alkane phase and bring about lower interfacial tension. [Pg.88]

In Table III the results of adding excess acid to sodium oleate solutions are given. These data are not directly comparable to Figure 5 since the aqueous phase contains cosolvent and the solutions were preequilibrated before testing. However, the trend to lower interfacial tension with increasing additions of oleic acid (and thus lower pH) is parallel to Figure 5 ... [Pg.88]

Interfacial Tension as a Function of Added Oleic Acid 0.01 M Sodium Oleate, 0.1 M Sodium Chloride,... [Pg.89]

The interfacial tension can be influenced by the penetration of the surfactant solution into the oily phase and the formation of new phases. A typical example is given in Figure 3.26 (19). This optical micrograph, taken under polarized light conditions, for oleic acid in contact with an aqueous solution of sodium dodecyl... [Pg.66]

The decreases in the water relative permeabilities of the high pH/high salt alkaline floods are directly contrasted with the increases in the relative permeabilities to water at the end of the moderate pH/high salt flood (compare the end point relative permeabilities column in Table 2). The increased permeability to water is believed to be caused by the formation of rigid interfacial films (which increases the resistance to flow in oil filled pores) and by the oil-wet conditions (under which water flows in the less restrictive flow paths). Such a reduction in permeability, which has been used to indicate the existence of a low tension mechanism (18), is not a valid low tension index since the interfacial tension minimum is only 3.5 dynes/cm and the capillary number is 1 x 10" for the buffered alkali/salt-oleic acid system. [Pg.271]

Tables 3.1 and 3.2 present surface tension values for many liquids as well as interfacial tensions for many water-containing interfaces. Calculate the initial spreading coefficient of aniline, oleic acid, butanol and bro-moform. Which of the liquids will spread on water and which will not Comment on the results. Tables 3.1 and 3.2 present surface tension values for many liquids as well as interfacial tensions for many water-containing interfaces. Calculate the initial spreading coefficient of aniline, oleic acid, butanol and bro-moform. Which of the liquids will spread on water and which will not Comment on the results.

See other pages where Interfacial tension oleic acid is mentioned: [Pg.250]    [Pg.531]    [Pg.88]    [Pg.92]    [Pg.159]    [Pg.471]    [Pg.503]    [Pg.208]    [Pg.336]    [Pg.170]    [Pg.267]    [Pg.336]    [Pg.388]    [Pg.277]    [Pg.279]   
See also in sourсe #XX -- [ Pg.81 ]




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