Modeling of equilibrium water vapor adsorption isotherms on activated carbon, alumina and hopcalite

A static volumetric method measured the equilibrium adsorption isotherms of water vapor on commercial activated carbon, alumina and hopcalite adsorbents. A type II isotherm represents water vapor adsorption on alumina and hopcalite, whereas a type V isotherm characterizes activated carbon. A method based on the sensitivity analysis of parameters is used to evaluate the estimability of unknown parameters involved in the Toth-Aranovich–Donohue (type II) and Mahle (type V) adsorption isotherm equations. The estimable parameters are then identified using experimental water vapor measurements at three different temperatures, i.e., 293, 303 and 313 K and pressures up to the saturated concentration, simultaneously. The isotherm modeling methodology is implemented and solved within COMSOL Multiphysics®. The results of the isotherm model using the fitted parameters show excellent agreement with the experimental measurements. Thus, this is confirmed by the performance indices such as the Pearson correlation coefficient and the mean square error. In addition, the isosteric water vapor heat of adsorption is estimated using the Clausius-Clapeyron equation and the temperature-dependent models developed for each adsorbent.