On microemulsion phase behavior and the monomeric solubility of surfactant

Abstract

In this paper we highlight the advantageous features of both short-and long-chain surfactant systems in determining the most important properties of three-phase bodies and genuine microemulsions. To this end Ðrst the phase behavior of the simple system (n-butyl monoglycol ether) is discussed. From H 2 OÈn-dodecaneÈC 4 E 1 temperatureÈconcentration sections through the phase prism at various water-to-oil ratios, a number of isothermal Gibbs triangles are constructed, which can quantitatively be compared with theories. Furthermore, the critical tie-lines of the three-phase body have been precisely determined. From these measurements it is evident that there is a non-negligible monomeric solubility of the surfactant in the excess phases. For long-chain surfactant systems, the more efficient the surfactant, the larger is the size of the microstructure of the microemulsion. We report a striking correlation between the efficiency of a surfactant and its monomeric solubility in the excess phases for 23 systems of the type These Ðndings suggest that the H 2 OÈn-alkaneÈC i E j . monomeric solubility of the surfactant in oil and water might be the key to describing the main features of these microemulsion systems.

Phase behavior of the surfactant ionic liquid trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate with water and dodecane

“…The latter is very important since these ternary systems represent (in a very simplistic way) the system that is found into a reservoir during surfactant flooding extraction. It is well known that Winsor type III systems (with three immiscible phases present) are directly related to a minimum water-oil interfacial tension, what is the basis of this enhanced oil recovery method [26][27][28]. Experiments on core flooding with ionic liquids have appeared recently [29].…”

Dramatic Enhancement of Enone Epoxidation Rates in Nonionic Microemulsions

“…[5] The H 2 O/NaOH/H 2 O 2 -n-octane/trans-chalcone-C 10 E 4 /C 10 E 5 -A C H T U N G T R E N N U N G (-DTAB) system: The phase behaviour of ternary and pseudo-ternary systems is usually studied in T(g) phase diagrams at a constant mass ratio a of oil-to-water plus oil, which is a representative cut through the corresponding phase prism. [10,30,31] Figure 1 shows a T(g) section of the pseudo-ternary system H 2 O/NaOH/H 2 O 2 -n-octane/transchalcone-C 10 E 4 /C 10 E 5 (-DTAB, 10 mol %) at d = m C 10 E 5 / (m C 10 E 5 + m C 10 E 4 ) = 0.225 and a = 0.4120, which corresponds to equal volumes of water and oil. The concentrations of the solutes in the water phase were c(H 2 O 2 , NaOH) = 0.30 m and of the substrate in n-octane c(trans-chalcone) = 0.15 m.…”

“…The X-point of the pure ternary system H 2 O-n-octane-C 10 E 4 is located at T = 24.3 8C. [31] The addition of NaOH shifts the X-point to lower temperatures. In our case, this effect was partially compensated by the addition of the more hydrophilic surfactant C 10 E 5 .…”

“…Therefore, the monomeric solubilities of the surfactants and cosurfactants in water and oil have been taken into account. [31,34] The surface area increases from S V À1 = 122 m 2 mL À1 in the C 10 E 4 /C 10 E 5 system to S V À1 = 212 m 2 mL À1 in the C 8 G 1 / C 8 E 0 system. DTAB was neglected in the calculation of the total specific interfacial area due to its considerably low amount in the solution.…”

Correlation of three-liquid-phase equilibria involving ionic liquids

“…Regarding systems involving surfactants, Buraeur et al [10] determined Gibbs phase triangles of the system water-dodecane-C 4 E 1 . The authors suggest, analyzing the behavior of different alkyl polyglycol ethers (C i E j ), that the monomeric solubility of the surfactant in oil and water might be the key to describe the main features of those microemulsion systems.…”