Adsorption of Sodium Dodecyl Sulfate and Butanol onto Acidic and Basic Alumina

• Published in: Journal of colloid and interface science 1996-09, Vol.182 (2), p.348-355
• Main Authors: Førland, Geir M., Rahman, Tamizur, Høiland, Harald, Børve, Knut J.
• Format: Article
• Language: English
• Subjects: admicelles; adsorption; Chemistry; co-surfactant; Exact sciences and technology; General and physical chemistry; hemimicelles; micelles; microemulsion; Solid-liquid interface; Surface physical chemistry; surfactant
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1006/jcis.1996.0473

The adsorption of sodium dodecylsulfate (SDS) and the co-adsorption of SDS and 1-butanol from aqueous electrolyte solutions and from microemulsions containing heptane onto acidic and basic aluminum oxide were measured. The aluminum oxides contain quasi-spherical highly porous particles with an amorphous structure. The measurements were carried out just above the Krafft temperature at 26°C. It is shown that the adsorption capacity of SDS and butanol onto the acidic alumina is slightly higher than that onto the basic. The adsorption of SDS decreases while butanol adsorption increases upon increasing alcohol concentration. The alcohol to surfactant mol ratio on the oxide surface reaches 2.3 for the acidic oxide and 2.1 for the basic oxide in solutions containing 0.8Mbutanol. The result indicates that to a certain degree, SDS becomes gradually replaced by butanol on the alumina surface. In order to describe the surfactant/alcohol exchange on the surface, a simple model is proposed and fitted to the obtained adsorption data. According to this model, the alcohol to surfactant area ratios in the adsorbed patches are 0.48 and 0.71 on the acidic and basic oxide respectively. Addition of heptane does not show any considerable alteration in the adsorption density of the surfactant and alcohol, which indicates that heptane does not solubilize to any appreciable extent in the adsorbed aggregates on the oxide surface.