Precipitation and Micellar Properties of Novel Mixed Anionic Extended Surfactants and a Cationic Surfactant

Abstract

Surfactant-modified mineral surfaces can provide both a hydrophobic coating for adsorbing organic contaminants and, in the case of ionic surfactants, a charged exterior for adsorbing oppositely charged species. This research evaluates the precipitation phase boundaries and synergistic behavior of the mixtures of carboxylate-based anionic extended surfactants with a pyridinium-based cationic surfactant. One cationic surfactant (cetylpyridinium chloride) and four anionic extended surfactants were studied. The anionic surfactants studied were ethoxy carboxylate extended surfactants with average carbon chain lengths of either 16 and 17 or 16 and 18 with 4 mol of a propylene oxide group and a different number of moles of an ethylene oxide group (2 and 5 mol). Precipitation phase boundaries of mixed anionic extended surfactants and cationic surfactant were evaluated to ensure that the surface tension studies are in regions without precipitate. Surface tension measurements were conducted to evaluate the critical micelle concentration of individual and mixed surfactant systems. Precipitation phase boundaries of these novel mixed surfactant systems showed greatly reduced precipitation areas as compared to a conventional mixed surfactant system which is attributed to the presence of the ethylene oxide and propylene oxide groups and resulting steric hindrances to precipitation. Moreover, it was demonstrated that the CMC of mixed surfactant systems were much lower than that of individual surfactant systems. Synergism was evaluated in the four systems studied by the b parameter which found that all systems studied exhibited synergism. From these results, these novel mixed surfactant systems can greatly increase formulation space (reduce the precipitation region) while maintaining synergism, although slightly reduced from conventional anionic-cationic mixtures reported previously.

Mixtures of Anionic/Cationic Surfactants: A New Approach for Enhanced Oil Recovery in Low-Salinity, High-Temperature Sandstone Reservoir

“…They assumed that the excess adsorption of cationic and anionic surface-active ions is in the form of ion pairs. The results of Paria and Khilar (2004) show that the adsorption of anionic surfactant onto a negatively charged surface is enhanced in the presence of cationic surfactant because of the formation of ion pairs.…”

Self‐Assembly Behaviors of Anionic–Cationic Binary Surfactant Systems in Poly(ethylene glycol) 200

“…Mixed surfactant solutions exhibit excellent performances in some physical and chemical properties in comparison with those of single-component surfactants, and hence the system has become an enduring topic of interest to many researchers [1][2][3][4][5]. The mixed surfactant systems are widely used in applications such as detergency, foaming generation, separation, and drug delivery [6][7][8].…”

“…In most applications, the chosen systems are the same type surfactants, as well as homologues; in contrast, sparse research has been done for the aqueous solutions of anionic-cationic surfactants mixtures due to the conventional wisdom of loss of surface activity induced by precipitation due to the electrostatic attraction between the two species of surfactant. In fact, binary mixtures of oppositely charged surfactants usually have better surface activity and lower critical micellization concentration (CMC) value than the single surfactant due to the strong electrostatic interaction between the polar headgroups of the surfactants [1,4].…”

Mixed Stability and Antimicrobial Properties of Gluconamide‐Type Cationic Surfactants

“…Surfactant mixtures widely used in a variety of industrial and commercial applications usually form mixed micelle aggregates that frequently exhibit remarkably different characteristic properties and have superior performance to those of individual components [6][7][8][9]. Mixtures of anionic and cationic surfactants can exhibit greater synergism than other mixed systems (anionic-anionic, cationic-cationic, ionic-nonionic, and nonionic-nonionic) [10][11][12][13][14][15]. However, the limitation of these mixed systems is their tendency to form crystalline precipitates in aqueous solution as a result of the columbic interaction between oppositely charged species [16,17].…”