Primary and secondary filling of micropores in active carbons

Abstract

Combined adsorption and calorimetric measurements have been used to examine the mechanism of micropore filling in active carbons. It appears that for carbons with medium and high degrees of burn-off (above 45–50%), the adsorption at low pressure does not correspond to the filling of narrow micropores, which are virtually absent, but to the initial step of the secondary filling (adsorption on the walls of wide micropores). The differential heat of adsorption is smaller than in narrow micropores and the extrapolation of the initial part of the non-linear Dubinin–Radushkevich plot corresponds approximately to the surface area of the supermicropores.