Adsorption of ethanol onto activated carbon: Modeling and consequent interpretations based on statistical physics treatment

In this work, we studied the adsorption of ethanol on three types of activated carbon, namely parent Maxsorb III and two chemically modified activated carbons (H-2-Maxsorb III and KOH-H-2-Maxsorb III). This investigation has been conducted on the basis of the grand canonical formalism in statistical physics and on simplified assumptions. This led to three parameter equations describing the adsorption of ethanol onto the three types of activated carbon. There was a good correlation between experimental data and results obtained by the new proposed equation. The parameters characterizing the adsorption isotherm were the number of adsorbed molecules (s) per site n, the density of the receptor sites per unit mass of the adsorbent N-m, and the energetic parameter p(1/2). They were estimated for the studied systems by a non linear least square regression. The results show that the ethanol molecules were adsorbed in perpendicular (or non parallel) position to the adsorbent surface. The magnitude of the calculated adsorption energies reveals that ethanol is physisorbed onto activated carbon. Both van der Waals and hydrogen interactions were involved in the adsorption process. The calculated values of the specific surface A(s), proved that the three types of activated carbon have a highly microporous surface. (C) 2015 Elsevier B.V. All rights reserved.