Use of liquid phase adsorption for characterizing pore network connectivity in activated carbon Suryadi Ismadji, Suresh K. Bhatia * Department of Chemical Engineering, The University of Queensland, St. Lucia, Brisbane, Qld 4072, Australia Abstract A simple percolation theory-based method for determination of the pore network connectivity using liquid phase adsorption isotherm data combined with a density functional theory (DFT)-based pore size distribution is presented in this article. The liquid phase adsorption experiments have been performed using eight different esters as adsorbates and microporous–mesoporous activated carbons Filtrasorb-400, Norit ROW 0.8 and Norit ROX 0.8 as adsorbents. The density functional theory (DFT)-based pore size distributions of the carbons were obtained using DFT analysis of argon adsorption data. The mean micropore network coordination numbers, Z, of the carbons were determined based on DR characteristic plots and fitted saturation capacities using percolation theory. Based on this method, the critical molecular sizes of the model compounds used in this study were also obtained. The incorporation of percolation concepts in the prediction of multicomponent adsorption equilibria is also investigated, and found to improve the performance of the ideal adsorbed solution theory (IAST) model for the large molecules utilized in this study. # 2002 Elsevier Science B.V. All rights reserved. PACS: 61.43.G; 64.60.A; 68.45.D Keywords: Activated carbon; Characterization; Network connectivity 1. Introduction Characterization of the pore structure of activated carbons is important to their applications in adsorption and separation processes, and is generally made in terms of their pore size distribution. Another impor- tant characteristic of the structure of activated carbons, which governs their reaction and transport properties is the connectivity of the pore network. This connec- tivity is usually quantified in the terms of the mean coordination number ,Z, which represents the number of pores meeting at a node or intersection in the network. Because of its influence on the transport properties of the carbon, this connectivity also affects the adsorption kinetics as well as dynamics in the solid. The most common and simple method for determination of the pore network connectivity is based on the percolation theory interpretation of nitro- gen sorption hysteresis [1–4] or mercury intrusion [5]. Recently, Seaton and co-workers [2] has also used other simple gas molecules such as CH 4 , CF 4 , and SF 6 , whose theoretical isotherms can be conveniently ana- lyzed by molecular simulation method, for determina- tion of pore network connectivity of activated carbon. Activated carbon is a complex material, which has a variety of surface groups, impurities, and irregularities, with the pore sizes ranging from micropores to macro- pores that are randomly connected in their pore Applied Surface Science 196 (2002) 281–295 * Corresponding author. Tel.: þ61-7-3365-4263; fax: þ61-7-3365-4199. E-mail address: sureshb@cheque.uq.edu.au (S.K. Bhatia). 0169-4332/02/$ – see front matter # 2002 Elsevier Science B.V. All rights reserved. PII:S0169-4332(02)00066-1