SURFACE-TENSION OF SURFACTANT SOLUTIONS IN THE PRESENCE OF COLLOIDAL SILICA

The dynamic surface tension of pure surfacant solutions containing 20% colloidal SiO2 was measured by the drop weight method. The equilibriu m surface tension was precisely determined from the kinetic curves. Th e ionic surfactants used were sodium dodecyl sulphate (SDS), cetyltrim ethylammonium bromide (CTAB) and sodium dodecylbenzenesulphonate (SDBS ). The nonionic surfactant used was a polyethoxylated alkylphenol. It was shown that the presence of colloidal SiO2 reduced the surface tens ion changes in surfactant solutions, especially for CTAB which was exp lained in terms of surfactant adsorption onto the colloidal SiO2/solut ion interface.