Determining the Preferred Alkane Carbon Number (PACN) of nonionic surfactants using the PIT-slope method
2017
Ontiveros, Jesús F. | Pierlot, Christel | Catté, Marianne | Salager, Jean Louis | Aubry, J.-M. (Jean-Marie)
In this paper the Phase Inversion Temperature (PIT) of the C10E4/n-Octane/0.01M NaCl(aq) emulsion was used as a reference to determine the changes introduced by adding small amounts of a second surfactant S2. The so-called PIT-slope method allowed the calculation of the dPIT/dx2 value, i.e. the linear variation of PIT with the molar fraction x2 of second surfactant S2. For nonionics polyethoxylated surfactants CiEj, dPIT/dx2 showed a linear dependency respect to the Preferred Alkane Carbon Number (PACN), one of the parameters of the HLD equation based on phase behavior. We calculated here the PACN from PIT and x2 data for CiEj and other nonionic surfactants derived from isosorbide or glycerol. When possible, the experimental PACN is determined from n-alkane scans at 25°C, and used to validate the proposed estimation method. The effects of changing the oil nature and water salinity on dPIT/dx2 are discussed in terms of the HLD equation and validates the hypothesis that allows calculate the PACN.
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