A onodisperse polystyrene latex (diam. 0.7 mm) was prepared in the absence of emulsifier. Adsorption isotherms of Na dodecylbenzenesulfonate and SDS on the latex particles were obtained by the surface tension method. The isotherms were of L2 and L4 types on the Giles classification and changed with the addition of NaBr. Explanations for the adsorption isotherms and the effect of the added salt were provided from the viewpoint of 2-stage adsorption, i.e., surfactant mols. were adsorbed in the first stage through the interaction with the solid surface while in the second through the hydrophobic interaction with the hydrocarbon chains of adsorbed surfactant mols.

Key words: SODIUM COMPOUNDS, SURFACE OF SOLIDS, ADSORPTION, POLYSTYRENE, ANIONIC SURFACTANTS, SODIUM SULFATE, LATEX, C12 COMPOUNDS, C12 COMPOUNDS, BENZENESULFONIC ACID P