Mixed adsorption of sodium dodecylsulfate and ethoxylated nonylphenol on TiO2 and the stability of TiO2 dispersions in sodium dodecylsulfate—ethoxylated nonylphenol mixed solutions

Abstract

The adsorption of sodium dodecylsulfate (SDS) and ethoxylated nonylphenol (NP-12) from their mixed solutions on TiO₂ and the stability of TiO₂ dispersions in SDS—NP-12 mixed solutions have been investigated. The NP-12 alone is almost not adsorbed on the TiO₂ surface. However, the amount of NP-12 adsorbed on TiO₂ increases by more than 50 times in the presence of a certain amount of SDS in solution, and decreases again at higher concentrations of SDS. The adsorption of SDS on the surface of TiO₂ from the SDS—NP-12 mixed solutions displays similar characteristics to a lesser degree. The stability of TiO₂ dispersions in the mixed solutions of SDS and NP-12 is shown to be consistent with the adsorption results. The synergistic and antagonistic effects of SDS and NP-12 on their adsorption on TiO₂ and on the stabilization of the TiO₂ dispersions were interpreted in terms of the formation of mixed hemimicelles on the TiO₂ surface and mixed micelles in solution.