A comparison between the Brunauer-Emmett-Teller adsorption equation, the G. Pickett (1945) adsorption equation, and the M. Dubinin (1947) micropore filling equation is made. Based on the assumption that multilayer adsorption and micropore filling occur simultaneously, a modified adsorption equation is derived. Comparison with experimental data shows that the modified equation is more accurate and is applicable over a wider range of pore radii. The cost of determing the pore distribution can be lowered greatly by using H instead of He as the carrier gas and the processing time can be reduced remarkably with the help of a computer.

Key words: COMPUTATIONAL METHOD, NITROGEN, HYDROGEN, COMPUTER APPLICATIONS, SPECIFIC SURFACE AREA, ADSORPTION EQUATION, PORE SIZE DISTRIBUTION