Surfactants form a unique class of chemical compounds. This review provides an introduction to the nature and physical properties of surfactants, emphasizing their ability to radically alter surface and interfacial properties and to self-associate and solubilize themselves in micelles. These properties provide the means to apply surfactants in wettability modification, detergency, and the displacement of liquid phases through porous media on one hand, and to stabilize dispersions (including foams, froths and emulsions), or to destabilize dispersions (again including foams and emulsions) on the other hand. These in turn lead to a vast array of practical application areas which are illustrated in terms of mineral and petroleum processing, biological systems, health and personal care products, foods, and crop protection.

http://www.beauty-review.nl/wp-content/uploads/2014/06/Surfactants-and-their-applications.pdf

2 Surfactants and their applications

The surfactants cesium, tetramethylammonium, tetraethylammonium, tetrapropylammonium and tetrabutylammonium dodecyl sulfates (CsDS, TMADS, TEADS, TPADS, and TBADS) have been synthesized by ion-exchange. The critical micellization concentration in the absence of added salt (cmc) has been determined at 10, 25, and 40 °C using the electrical conductivity method. The cmc was found to decrease in the sequence CsDS > TMADS > TEADS > TPADS > TBADS. The value of the cmc depends very little on temperature, going through a shallow minimum around 25 °C for most surfactants investigated. The micelle aggregation numbers have been determined using the time-resolved fluorescence quenching method, with the pyrene/dodecylpyridinium chloride as fluorescent probe/quencher pair, at various surfactant concentrations and, in the case of TMADS, in the presence of tetramethylammonium chloride. The micelle ionization degree α0 at the cmc has been determined from the electrical conductivity data and the values of the aggregation n...

http://www.csun.edu/~vcphy00s/Bales78.pdf

Effect of the Nature of the Counterion on the Properties of Anionic Surfactants. 1. Cmc, Ionization Degree at the Cmc and Aggregation Number of Micelles of Sodium, Cesium, Tetramethylammonium, Tetraethylammonium, Tetrapropylammonium, and Tetrabutylammonium Dodecyl Sulfates

Supramolecular solvents in the extraction of organic compounds. A review.

Clouding behaviour in surfactant systems.

https://repositorium.sdum.uminho.pt/bitstream/1822/19930/1/vaz_2012.pdf

Performance of a biosurfactant produced by a Bacillus subtilis strain isolated from crude oil samples as compared to commercial chemical surfactants.

Anionic surfactants are not known to show a clouding phenomenon in aqueous solutions. On the other hand, this is a general feature for nonionic surfactants. Here the effect of addition of tetra-n-butylammonium bromide (Bu4NBr) on the clouding phenomenon in sodium dodecylbenzenesulfonate (SDBS) has been studied by measuring cloud points (CP) for each combination. Similar type of studies were also performed with poly(ethylene glycol) t-octylphenyl ether (TX-100). The CP varies in an opposite manner for the two classes of surfactants, which is explained in terms of charge variation in each type of micelles by the addition of Bu4NBr. A relationship between [SDBS] vs [Bu4NBr] has been worked out for getting the CP − phenomenon in SDBS solutions:  nearly one Bu4NBr molecule is needed for each two SDBS monomers for getting the CP in the system. With 10-mM SDBS, the addition of Bu4NBr shows an interesting phase behavior, where a stable colloidal phase with bluish − white appearance (preclouded) appears preceded b...

Salt-induced cloud point in anionic surfactant solutions: Role of the headgroup and additives

Here we report the clouding phenomenon with sodium dodecyl sulfate (SDS) in combination with tetra-n-butylammonium bromide (Bu4NBr). Cloud point (CP) vs [Bu4NBr] curves are constructed for various fixed [SDS], and the minimum Bu4NBr concentrations required to produce CP are determined. A relationship between [SDS] and [Bu4NBr] is established that exists down to fairly low [SDS]. The presence of aromatic hydrocarbons (added up to their solubility limits) decreases the CP of a fixed SDS−Bu4NBr system. Furthermore, an increase in hydrophobicity of the aromatic hydrocarbon decreases the CP. An unusual CP-decreasing effect of thio compounds is observed, which is discussed in terms of direct interaction of these compounds with anionic SDS micelles.

and Ziya Ahmad Khan

Papers

Salt-induced cloud point in anionic surfactant solutions: Role of the headgroup and additives

Occurrence of Cloud Points in Sodium Dodecyl Sulfate−Tetra-n-butylammonium Bromide System