Investigation of adsorption process of benzene and toluene on activated carbon by means of grand canonical ensemble

In this work, the performances of a commercial activated carbon (Filtrasorb 400, provided by Calgon) were experimentally tested for the adsorption of different aromatic compounds, i.e., toluene and benzene from synthetic groundwater. Batch adsorption tests were carried out at constant pH (8) and four different temperatures (10-50 °C). The experimental equilibrium adsorption data were fitted with a new statistical physics model named as 'multilayer model with saturation' and established through the grand canonical ensemble in statistical physics. The characteristic model parameters of the adsorption isotherm such as the number of benzene or toluene molecule(s) per site, n, the receptor site densities, NM, the number of adsorbed layers (NL) and the energetic parameter, (-ε1) and (-ε2), were estimated for the studied systems by a non-linear least square regression. These parameters were discussed and interpreted for their temperature dependence. The calculated thermodynamic parameters such as entropy, Gibbs free energy and internal energy from experimental data showed that the adsorption of benzene and toluene onto activated carbon Filtrasorb 400 was feasible, spontaneous and exothermic in nature.