Abstract
In this study, the adsorption of a cationic surfactant (CTAB) and a nonionic surfactant (Triton X-100) on precipitated silica and the adsolubilization of two organic solutes, toluene and acetophenone, were investigated in both single- and mixed-surfactant systems. In mixed-surfactant systems, the adsorption was studied at three different molar ratios, 1:1, 3:1 and 1:3, while the adsolubilization was studied in both single- and mixed-solute systems. The adsorption results showed that the addition of Triton into the mixed CTAB/Triton surfactant systems caused a reduction of CMC when compared to the pure CTAB system. The adsorbed amount of each surfactant was found to be quite close to the molar ratio of CTAB/Triton in the mixed systems. In single-solute systems, the adsolubilization of toluene appeared to be directly related to the amount of surfactant adsorbed on silica surface for both single- and mixed-surfactant systems. For acetophenone, when compared to single-surfactant systems, the adsolubilization was much higher in the mixed-surfactant systems, especially at molar ratios of 3:1 and 1:1. In mixed-solute systems, the synergistic effect was observed in the adsolubilization of acetophenone in the presence of toluene whereas the presence of acetophenone had little effect on the adsolubilization of toluene.
