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Updated: Jul 31, 2026

Phase Diagram Characterization Using Magnetic Beads as Liquid Carriers
Published on: September 4, 2015
Thermodynamic studies of mixed ionic/nonionic surfactant systems
B M Razavizadeh1, M Mousavi-Khoshdel, H Gharibi
1Department of Chemistry, Khorassn Science and Technology Park, P.O. Box 91735-139, Mashhad, Iran.
Abstract:
Mixtures of alkyltrimethylammonium bromide (CnTAB, n=12, 14, 16, 18) and Triton X-100 were studied at a range of mole fractions of ionic surfactant per nonionic surfactant. For each mixture, the cmc obtained from surface tension measurements differed from that obtained using potentiometry. The behavior of these mixed-surfactant systems showed three different regions with increasing total surfactant concentration. From the surface tension and potentiometry data, we obtained the free monomer concentration of ionic surfactant (mi), the micellar mole fraction of surfactant (xi), and the degree of dissociation (alpha) of ionic surfactant. We also obtained the free monomer concentration of Triton X-100 (m2) using PFG-NMR technique. A new equation was introduced to evaluate the activity coefficient in the micellar phase. The excess free energy (GE) and the synergetic parameters of mixtures were determined at various mole fractions of CnTAB/Triton X-100. Finally, the complexity of the synergism parameters was investigated.
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