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Cationic surface complexes, interfacial

Cationic Surface Complexes. The first paper of the series (4), in a section entitled Preliminary Approach to the Interfacial Coordination Chemistry of Hydrous Oxides, addressed the mechanism of cation adsorption by hydroxylated mineral surfaces. Here the term coordination was reserved for complex formation between cations and surface functional groups through bonding that can be either electrostatic or covalent, or a mixture of both. The dichotomous qualification is much in the spirit of the classic Stem (11) picture of strong adsorption. [Pg.47]

These requirements would be fulfilled if SDS were bound to the BSA monolayer in the form of small aggregates or pseudo-micelles. Such aggregates have been demonstrated to be formed as the result of the interaction of SDS and BSA in solution (2). Further, the electrostatic nature of the interaction was demonstrated by the fact that the complex was completely dissociated by adjusting pH to values above 10.0. Therefore, it is suggested that the cause of the marked shift in pK of the ammonium groups of the SDS-BSA surface complex was the presence of aggregates of SDS bound at cationic sites of the protein monolayer. It may be inferred from this hypothesis that the natural result of the interaction of anionic lipids with an interfacial protein film is the formation of a mosaic structure—one of the proposed characteristics of biological membranes. [Pg.162]

If the interaction between an anionic surfactant and a cationic surfactant results in a water-soluble complex, how do we know that the complex is really formed If, indeed, the anionic and cationic surfactants are neutralized, then is the resulting complex a nonionic surfactant and to what extent does it behave like nonionic surfactants Ethoxylated nonionic surfactants have the unique property of cloud point phenomena they become cloudy above a given temperature, known as the cloud point temperature. If, indeed, the resulting anionic-cationic complexes are neutralized, would they exhibit cloud point phenomena The answer to these questions is yes imder special conditions and has been demonstrated previously [36]. In the following subsections, results of surface and interfacial tensions and cloud point phenomena, and additional properties of the complexes will be given. [Pg.145]

FIG. 6 Interfacial complexation reactions of protons at the solvent-metal oxide interface. Molarity of protons in solution, xjj. Mole fraction of (1) unprotonated anionic surface sites, 0 Q, (2) monoprotonated nonionic surface sites, G SOH, and (3) diprotonated cationic surface sites, 0SOH2... [Pg.231]

The surface acid or base sites in combination with adsorbed hydrated cations or anions, represented by -0 (a) K or -OH2 (b) A , are called the interfacial ion pair [Tamura-Puruichi, 1991]. In some cases the surface acid or base site is covalent-bonded with dehydrated cations or anions to form an interfacial complex [Stumm, 1992]. [Pg.182]

The negative layer charge is mostly neutralized by the hydrated cations in the interlayer space. These cations are bonded to the internal surfaces by electrostatic forces, and they are exchangeable with other cations. The interaction strength between the hydrated cation and the layers (the internal surface) increases when the charge of the cation increases, and the hydrated ionic radius decreases. Cations with hydrate shell can be considered as outer-sphere complexes. Cation exchange is the determining interfacial process of the internal surfaces of montmorillonite. [Pg.86]


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Cationic surface

Interfacial complex

Surface cations

Surface complex

Surface complexation

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