Use of n-nonane pre-adsorption for the determination of micropore volume of activated carbon aerogels

When the αs or t methods and the DR (Dubinin–Radushkevich) or DA (Dubinin–Astakhov) Equations are used to analyse nitrogen adsorption isotherms determined at 77 K on activated carbon aerogels it is found that, in contrast to the behaviour generally found with other carbon materials, the αs or t estimate of micropore volume is significantly less than the DR or DA estimate. In this paper the reasons for the overestimation of the DA micropore volume and underestimation of the αs micropore volume are explained and it is shown how use of the n-nonane pre-adsorption method enables consistent values of micropore volume to be obtained.