Studies of surface and structural heterogeneities of microporous carbons by high-resolution thermogravimetry

Abstract

Abstract A high-resolution thermogravimetric analyzer (HR TGA), i.e., TGA with automatically programmed temperature control, was used to study the thermodesorption of water, n-butanol, benzene, and n-octane from active carbons with different porosities and surface heterogeneities. The microporous carbons were exposed to the above adsorptives by two different methods: (i) by immersing them in the pure liquid, and (ii) by exposing them to vapor of the liquid. The measured weight-loss curves contained steps, which reflected evaporation of the liquid from meso- and micropores, and the thermodesorption of adsorbed molecules from the carbon surface. The heights of these steps were directly correlatable to the total porosity and microporosity of the samples studied. In addition, the high-temperature steps of the HR TGA curves showed a significant broadening arising from the microstructural and surface heterogeneities of the active carbons.