Mixed adsorption of sodium dodecylsulfate and ethoxylated nonylphenol on TiO 2 and the stability of TiO 2 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 TiO 2 and the stability of TiO 2 dispersions in SDS—NP-12 mixed solutions have been investigated. The NP-12 alone is almost not adsorbed on the TiO 2 surface. However, the amount of NP-12 adsorbed on TiO 2 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 TiO 2 from the SDS—NP-12 mixed solutions displays similar characteristics to a lesser degree. The stability of TiO 2 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 TiO 2 and on the stabilization of the TiO 2 dispersions were interpreted in terms of the formation of mixed hemimicelles on the TiO 2 surface and mixed micelles in solution.