Computer analysis of the effect of the type of activating agent on the formation of the porous structure of activated carbon monoliths

An Evaluation of the Reliability of the Results Obtained by the LBET, QSDFT, BET, and DR Methods for the Analysis of the Porous Structure of Activated Carbons

“…Therefore this research involves a comparative analysis of the methods employed to describe the porous structure of adsorbents and the adsorption process on the surface of activated carbons (i.e., the Brunauer–Emmett–Teller (BET) [ 29 ] and the Dubinin-Radushkevitch (DR) [ 30 ] methods) based on models that offer the highest simplification of reality and, consequently, the least reliable ones. Moreover, the most recent methods for structural analysis were also applied using advanced mathematical and computer-based tools, considering in particular the surface heterogeneity of the analyzed material (namely, the numerical clustering based adsorption analysis (LBET) method [ 31 , 32 , 33 , 34 , 35 ] and the Quenched Solid Density Functional Theory (QSDFT) method [ 36 , 37 , 38 , 39 , 40 ]). Special attention was paid in the analyses to the limitations of the relevant theoretical models of the methods and critically analyzing the output data for their reliability and actual usability in research work.…”

“…However, unlike the BET model, LBET models consider the surface heterogeneity, the possibility of adsorbate molecule cluster branching, and the geometrical and energy limitations of the formation of clusters of adsorbate molecules. The LBET method was supplemented with the advanced numerical fast multivariate procedure of adsorption system identification [ 31 , 32 , 33 , 34 , 35 ].…”

“…The LBET method, the theoretical foundations of the LBET models and their derivations, and the numerical fast multivariate procedure for adsorption system identification are described in detail in earlier publications. Here, we provide an overview of the most important information concerning the mathematical LBET models of adsorption on the homogeneous and heterogeneous surfaces of carbonaceous adsorbents that are implemented in this method and are indispensable for the correct interpretation of the results [ 31 , 32 , 33 , 34 , 35 ].…”

“…Moreover, it was assumed that each site available on that layer is equally probable to be matched with any adsorbate molecule, with no regard to the occupancy of other sites. Moreover, each cluster of adsorbate molecules contains a single molecule in the primary adsorption site, and the enlargement of a cluster does not impact the appearance and growth of other clusters [ 31 , 32 , 33 , 34 , 35 ].…”

“…Provided that each cluster of adsorbate molecules can occupy only a specified space and size, the general formula for the coverage ratio θ κn is expressed in the following form [ 31 , 32 , 33 , 34 , 35 ]: where index κ counts the k -th type clusters of adsorbate molecules for an identical energy profile across layers n = 1, …, k ; Q κn is the molar energy contributed by placing an adsorbate molecule at the n -th layer of κ -th class clusters; π is the relative pressure of the adsorbate; R is the gas constant; T is the temperature; k is the maximum number of layers, i.e., the size of the molecule adsorbate cluster; and β κn is the pore shape factor.…”