This title appears in the Scientific Report : 2015 

Unusually sluggish microemulsion system with water, toluene and a technical branched alkyl polyethoxylate
Ilic, Marija
Haegel, Franz-Hubert / Pavelkic, Vesna / Zlatanovic, Snezana / Markovic, Zoran / Cvjetic, Aleksandar
Agrosphäre; IBG-3
Chemical industry & chemical engineering quarterly, 21 (2015) 3, S. 429 - 439
Belgrade Association of Chemical Engineers 2015
10.2298/CICEQ141012045I
Journal Article
Terrestrial Systems: From Observation to Prediction
Please use the identifier: http://dx.doi.org/10.2298/CICEQ141012045I in citations.
Microemulsion systems with water, toluene and nonionic surfactants are interesting for application due to the excellent solvent properties of aromatic hydrocarbons. In this study, the pseudo-binary phase diagram (“fish-diagram”) of such a ternary system was investigated using a branched technical alkyl polyethoxylate. Lutensol ON 50 (i-C10E5) was considered a suitable surfactant. The system with technical branched i-C10E5 exhibits very long and for compositions near optimum solubilization, i.e. the minimum content of surfactant needed for a bicontinuous microemulsion, extremely long times for equilibration. In addition to visual observation, qualitative measurements of turbidity were performed with a UV-Vis spectrometer for characterizing the behavior of this unusually sluggish system. Isothermal phase diagrams at 20, 25 and 30°C yielded inconsistent results after the change of temperature and the application of mechanical stress for different treatment of the samples. Ternary mixtures of water, toluene, and Lutensol ON 50 seem to form long-living metastable states. The sluggishness and the ambiguous phase behavior of the system are discussed. Inconsistent results are attributed to the slow kinetics of the formation and destruction of liquid crystals and the ability of the system to form miniemulsions within an unusual concentration range.