Abstract

SALMON-VEGA, S.; HERRERA-URBINA, R.; VALDEZ, M. A.  and  LIRA-GALEANA, C.. Effect of the concentration of ionic surfactants on the electrokinetic behavior of asphaltene precipitated from a maya mexican crude oil. Rev. Mex. Ing. Quím [online]. 2010, vol.9, n.3, pp.343-357. ISSN 1665-2738.

In this work we show the behaviour of the zeta potential of asphaltene when different concentrations of two cationic surfactants (cetylpyridinium chloride and dodecylamine hydrochloride) and one anionic surfactant (sodium dodecyl sulphate) interact with asphaltene particles at different pH in the aqueous phase. Asphaltene, precipitated from a Maya Mexican crude oil, was observed by Transmission electron micrographs showing that asphaltene is constituted of nanometric particles smaller than 50 nm in diameter. By changing the concentration of cetylpyridinium chloride, dodecylamine hydrochloride and sodium dodecyl sulphate from 0.01 mM to 1 mM, we were able to reverse and control the sign of the zeta potential of asphaltene, demonstrating the presence of both electrostatic and hydrophobic interaction s at the asphaltene surface. Thete interactions were alto observed by interfacial tension measurements at the toluene - water interface. It has been noticed that for low and high pH in the aqueous phase, the presence of dodecylamine hydrochloride and sodium dodecyl sulphate were not determinant on the asphaltene interfacial tension. On the contrary for pH near the IEP and pH neutral, these surfactants were more effective. The presence of cetylpiridinium hydrochloride in the aqueous phase changed the asphaltene interacial tension to very low values independent of the pH.

Keywords : asphaltene; zeta potential; ionic surfactants; interfacial tension; pH.

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