Surfactant adsorption nonionic

A characteristic of the early neutron reflectivity studies of nonionic surfactant adsorption was some variability in the pattern of adsorption. This was investigated in more detail and more systematically by McDermott et al. [55], who compared the adsorption of Ci2E6 onto a range of different substrates, amorphous silica, crystalline quartz, and the oxide layer on a silicon single crystal. The adsorbed surfactant was found to form a bilayer with an overall thickness 49 4 A, with a structure similar to that determined in the previous studies (see Fig. 4). 

The Stem-Martynov isotherm does not take into account the intermolecular interaction of adsorbed molecules, as it is considered in the Frumkin isotherm (cf Eq. (2.43)). The classical version of the Framkin isotherm was derived for nonionic surfactant adsorption layers. The incorporation of electrostatic interaction was proposed by Borwankar Wasan (1986, 1988). 

Dependence of Adsorption, on Rock Type. Table I shows that gas injection EOR projects are being conducted in sandstone and carbonate pools. Hydrocarbon- and C02-misdble projects are run largely in carbonate reservoirs. With the exception of several studies that report adsorption levels of EOR surfactants on carbonates (4,11,12, 24, 33, 62—64, 86), the petroleum literature has dealt almost exclusively with anionic, and sometimes nonionic, surfactant adsorption on sandstones, because most studies have been carried out with surfactants used in low-tension flooding. These surfactants are not considered suitable for application in carbonate reservoirs because of their low salinity and hardness tolerance. Foam-forming surfactants suitable for high-salinity environments include amphoteric surfactants (2). The adsorption behavior of this surfactant type has also rarely been studied (10—12, 87, 88). 

Due to diphylic character of MR and its ability of self-organization in a solution it can behave similarly to nonionic surfactants. Adsorption of MR was shown to be mixed-diffusion barrier controlled (pH 7.4). MR was also shown to change thermodynamic affinity of lysozyme to the solvent with the resulting the protein being slightly less or more surface active depending on MR concentration. Under used conditions MR and lysozyme can compete in adsorption process at air/water interface [4]. 

Carasso, M.L., Rowlands, W.N. and O Brien, R.W. (1997) The effect of neutral polymer and nonionic surfactant adsorption on the electroacoustic signals of colloidal silica. Journal of Colloid and Interface Science, 193, 200-214. 

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