EFFECT OF SODIUM DODECYLSULFATE AND CETYLPYRIDINIUM CHLORIDE ACT AS TEMPLATES AT DIFFERENT PH VALUES ON SORPTION AND TEXTURAL PROPERTIES OF MESOPOROUS SILICAS

摘要

Cationic and anionic surfactants are used for structuring of the negatively charged silica species during the formation of ordered mesoporous silicas from stable dilute silica sols, obtained by ion-exchange method. Isotherms of nitrogen adsorption-desorption at 77 K on silicas, which are prepared by the thermal decomposition of silica hydrogels, obtained at different pH using sodium dodecylsulfate or cetylpyridinium chloride as surfactants, are measured. The shape of the capillary condensation hysteresis and the type of the sorption isotherms are identified using the IUPAC classification. It is found that the adsorption and textural properties of the silica gels depend on the concentration and the type of surfactant (SAA), and also on pH.