Investigation of network connectivity in activated carbons by liquid phase adsorption

Abstract

The connectivity of the pore network is an important aspect of the structure of porous materials. In this paper we propose a simple percolation theory based method for the determination of pore network connectivity of microporous carbons, using liquid-phase adsorption isotherm data combined with a DFT based pore size distribution. Aqueous phase esters were used as model adsorptives in the experiments, and the isotherms interpreted by the pore filling approach. The Dubinin-Radushkevich equation was modified for nonideality of the bulk phase, which yielded improved correlation of the adsorption data. Based on the estimated saturation capacities, the network coordination number of the carbon adsorbent was determined by the proposed method. In addition, the critical molecular sizes of model esters used in this study, which are largely unknown, were also extracted, and the results quantitatively matched those obtained theoretically from simulation of the molecular structure of the esters.