Wettability alteration by CTAB adsorption at surfaces of SiO2 film or silica gel powder and mimic oil recovery

The adsorption of cetyl trimethylammonium bromide (CTAB) at a smooth surface of SiO2 film was determined by Ellipsometry. The result is in agreement with a two step model of the adsorption. Its monolayer and bilayer adsorption occurred at different concentrations of the CTAB aqueous solutions. The adsorption is consistent with the wettability change of the film surface. The wettability of the CTAB solutions on a silica gel powder was determined by amodifiedWashburn equation. The interfacial tension (g) between dodecane and the dilute CTAB aqueous solution was obtained using the pendantmethod. The relationship between the wettability of the powder surface, the critical micelle concentration (CMC) of CTAB and the mimic oil recovery of the residual oil on the powder surface has been explored. It has been found that good residual oil recovery can be achieved by the surface wettability changes at normal interfacial tensions (100–102 mN m 1) and no formation of emulsion was observed. # 2003 Elsevier B.V. All rights reserved.