Adsolubilization of 4-nitrophenol at a kaolinite/water interface as a function of pH and surfactant surface coverag - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Colloid and Interface Science Année : 2003

Adsolubilization of 4-nitrophenol at a kaolinite/water interface as a function of pH and surfactant surface coverag

Résumé

The incorporation of a weak acid, 4-nitrophenol, into a kaolinite/water interface has been achieved by the addn. of an adsorbing cationic surfactant, cetylpyridinium chloride. This so-called adsolubilization phenomenon has been studied as a function of surfactant concn. and of pH. In the absence of the surfactant 4-nitrophenol is hardly adsorbed onto the naked kaolinite particles in the whole pH range studied, from 3 to 10. At const. pH, the adsolubilization is at a max. at a surfactant concn. corresponding to the onset of the satn. plateau. At still higher concns., the solute is distributed between the surface and free aggregates. The influence of the pH on adsolubilization is very much dependent upon surfactant surface coverage. At low surfactant concn. the behavior of 4-nitrophenol is very similar to that obsd. with the same surfactant at a silica/water interface: the adsolubilization decreases with increasing pH as the result of the repulsive interaction between the deprotonated solute mol. and the neg. charged sites on kaolinite particles. At higher surfactant concns. increasing the pH induces increased adsolubilization as a consequence of the favorable interaction which takes place between the deprotonated weak acid and the pos. charged surface surfactant aggregates. Hence, depending upon the extent of surface coverage, increasing the pH may retain 4-nitrophenol at the kaolinite/water interface or reject it into the bulk micellar soln.
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Dates et versions

hal-00165133 , version 1 (24-07-2007)

Identifiants

  • HAL Id : hal-00165133 , version 1

Citer

Delphine Talbot, Agnes Bee, Claude Treiner. Adsolubilization of 4-nitrophenol at a kaolinite/water interface as a function of pH and surfactant surface coverag. Journal of Colloid and Interface Science, 2003, 258 (1), pp.20-26. ⟨hal-00165133⟩
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