INVESTIGATION ON THE POROSITY OF SILICA-GEL BY THERMAL-DESORPTION OF LIQUIDS

Thermogravimetric analysis was applied to the characterization of the porosity of silica gel. Thermal desorption of n-butanol was investigated by using various heating programs. The influence of desorption conditions on the values of structural parameters of silica gel is discussed. Experimentally obtained curves representing weight loss of adsorbate against temperature were converted into a plots of the volume loss versus pore radius. The transformation was performed using the Kelvin equation. By the differentiation of these curves the pore size distributions for silica gel at different desorption conditions were calculated. Taking into account the amount of the liquid adsorbate desorbed above its normal boiling point the total pore volume of the silica was estimated. Results from the thermogravimetric method are compared with those obtained from the nitrogen method. The consistency of the parameters characterizing the porous structure of silica gel obtained by two different methods is satisfactory.