Quantitative effect of nonionic surfactant partitioning on the hydrophile-lipophile balance temperature

Mahjoud Ben Ghoulam (1) , Nadia Moatadid (1) , Alain Graciaa (2) , Jean Lachaise (2)

1 UMI - جامعة مولاي إسماعيل = Université Moulay Ismaïl
2 TEFC - Thermodynamique et Energétique des fluides complexes

Phase behaviors of water/nonionic surfactants/isooctane systems are determined experimentally in temperature-global surfactant concentration diagrams. The surfactants are monodistributed polyoxy- ethylene glycol n-dodecyl ether. They are used as model mixtures of two, three, or five compounds or as constituents of a commercial surfactant. It is found that the phase diagrams of these systems are bent gradually toward the highest temperatures as the global surfactant concentration decreases. Each phase diagram is well-characterized by the curve of the HLB (hydrophile-lipophile balance) temperature versus the global surfactant concentration. For any fixed global surfactant concentration, this temperature is the middle temperature of the three-phase region; it can be calculated from an additive rule of the HLB temperatures of the surfactants weighted by their mole fractions at the water/oil interface. These mole fractions are determined through the pseudophase model using surfactant partitioning. Calculations require the knowledge of the critical micelle concentration, the partition coefficient between water and oil, and the HLB temperature of each surfactant of the mixture. This treatment can be used to correctly predict the variation of the HLB temperatures of the surfactant mixtures studied versus the global surfactant concentration. Furthermore, these calculations show that the observed curvature of the phase diagrams at the lowest global concentrations is due to the most favorable partitioning toward the oil of the lowest ethoxylated surfactant molecules.

Mots clés: Engineering controlled terms: Critical micelle concentration; High temperature effects; Hydrophilicity; Interfaces (materials); Mathematical models; Mixtures; Numerical analysis; Phase diagrams Engineering uncontrolled terms: Hydrophile lipophile balance; Isooctane; Mole fractions; Nonionic surfactant; Polyoxyethylene glycol dodecyl ether Engineering main heading: Surface active agents EMTREE drug terms: lipid; surfactant; water EMTREE medical terms: article; chemistry; physical chemistry; temperature MeSH: Chemistry; Physical; Hydrophobicity; Lipids; Surface-Active Agents; Temperature; Water Medline is the source for the MeSH terms of this document.; Water Medline is the source for the MeSH terms of this document

Domaines: Chimie-Physique [physics.chem-ph]

Mahjoud Ben Ghoulam, Nadia Moatadid, Alain Graciaa, Jean Lachaise. Quantitative effect of nonionic surfactant partitioning on the hydrophile-lipophile balance temperature. Langmuir, 2004, 20 (7), pp.2584-2589. ⟨10.1021/la030306u⟩. ⟨hal-00691215⟩