Investigation of porous structure and surface properties of controlled porosity glasses

A series of controlled porosity glasses were prepared from the same raw material by leaching with basic solution for different periods of time. Adsorption isotherms of n-octane and toluene were determined by elution gas chromatography. From the adsorption isotherms, the dispersion and polar components of the surface free energy were calculated, and also the adsorption energy distribution function for adsorption of n-octane and toluene. The results are discussed in terms of both porous structure and surface chemistry. It may be concluded that a gradient distribution of alkali-borate constituents appears very close to the surface, and that prolonged leaching with a base does not change the strictly surface properties. The results are also discussed in terms of the type of surface-molecule interactions.