Powierzchniowe i strukturalne właściwości niemodyfikowanych i modyfikowanych żeli krzemionkowych

Of the set of methods for the characterization of the surface and structural properties of unmodified and modified mesoporous silica gels (which is reviewed in the present paper), special consideration was given to the BET, [alfa]s-plot and Dollimore-Heal methods for the characterization of the adsorption process. For the needs of these characterization, use was made of the low-temperature (77 K) nitrogen adsorption isotherms on unmodified and octyl phase modified silica gel Nitrogen adsorption isotherms on unmodified and modified macroporous LiChrospherSi-1000 silica were used as the reference data. As shown by the results, an accurate characterization of nanoporous silica gels requires that the adsorption data be measured in the entire range of relative pressures. Another crucial problem is the selection of the reference solid because the resulting parameters of the porous structure depend on the reference adsorption isotherm used. The reference silica should display properties analogous to those of the silica studied.