STRUCTURE OF SURFACE AGGREGATES OF TETRADECYLPYRIDINIUM IONS ON POROUS SILICAS IN THE PRESENCE OF NITRATE AND SALICYLATE COUNTERIONS

The saturation values of tetradecylpyridinium ion adsorption on silica s with different pore structures are determined in the presence of nit rate and nitrate-salicylate counterion mixtures. These data are compar ed with the calculated maximum loading capacity of the porous supports . The calculations are based on the available space inside pores, depe nding on the mean pore diameter of a support on the one hand and diffe rent models of surfactant adsorbates, discussed in literature, on the other hand. The best correlation between theoretically predicted adsor ption and experimental adsorption data is obtained for the spherical s urface micelle model according to Gu on silicas with mean pore diamete r between 4 and 20 nm. Surfactant bilayers with interpenetrating alkyl chains also describe the experimental data fairly well. Bilayers with nonpenetrating alkyl chains can be ruled out as possible structure of surfactant cations in adsorbates in porous silicas.